Left Distal Middle Cerebral Artery Research Articles

Use of Botulinum Toxin for Limb Immobilization for Rehabilitation in Rats with Experimental Stroke.

Motor rehabilitation strategies after unilateral stroke suggest that the immobilization of the healthy, unimpaired limb can promote the functional recovery of a paretic limb. In rodents, this has been modeled using casts, harnesses, and other means of restricting the use of the non-paretic forelimb in models of experimental stroke. Here, we evaluated an alternative approach, using botulinum toxin injections to limit the function of the non-paretic forelimb. Adult male rats were subjected to permanent ligation of the left distal middle cerebral artery, resulting in right forelimb paresis. The rats were then subjected to: (1) no treatment; (2) botulinum toxin injections 1 day post stroke; or (3) cast placement 5 days post stroke. Casts were removed after 5 weeks, while the botulinum toxin injection effectively immobilized subjects for approximately the same duration. Rats with bilateral forelimb impairment due to the stroke plus casting or botulinum injections were still able to feed and groom normally. Both immobilization groups showed modest recovery following the stroke compared to those that did not receive immobilization, but the casting approach led to unacceptable levels of animal stress. The botulinum toxin approach to limb immobilization had both advantages and disadvantages over traditional physical limb immobilization. The major advantage was that it was far less stress-inducing to the subject animals and appeared to be well tolerated. A disadvantage was that the paresis took roughly 10 weeks to fully resolve, and any degree of residual paresis could confound the interpretation of the behavioral assessments.

Propofol ameliorates ischemic brain injury by blocking TLR4 pathway in mice.

Ischemic brain injury is one of the most serious perioperative complications. However, effective preventative methods have not yet been established. This study aimed to investigate whether propofol has neuroprotective effects against ischemic brain injury, with a specific focus on Toll-like receptor 4 (TLR4). Focal brain ischemia was induced via a combination of left common carotid artery occlusion and distal left middle cerebral artery coagulation in mice. Either propofol (10 mg/kg) or vehicle was intravenously injected 10 min prior to the induction of brain ischemia in wild-type and TLR4 knockout mice. Infarct volume, pro-inflammatory cytokine expression, inflammatory cell infiltration, and neurobehavioral function were assessed. Propofol administration significantly reduced infarct volume in wild-type mice (26.9 ± 2.7 vs 15.7 ± 2.0 mm3 at day 7), but not in TLR4 knockout mice. Compared with the control mice, the propofol-treated wild-type mice exhibited lower levels of IL-6 (0.57 ± 0.23 vs 1.00 ± 0.39 at 24 h), and smaller numbers of TLR4-expressing microglia in the penumbra (11.7 ± 3.1 vs 25.1 ± 4.7 cells/0.1 mm2). In conclusion, propofol administration prior to ischemic brain insult attenuated brain injury by blocking the TLR4-dependent pathway and suppressing pro-inflammatory cytokine production.

Management of Mobile Thrombus With Distal Protection Devices During Carotid Artery Angioplasty: 2-Dimensional Operative Video.

Embolic protection devices (EPDs) have become a standard of care during internal carotid artery revascularization.1,2 This video is about a 57-yr-old-male who presented with a wake-up stroke with a left hemispheric syndrome. Head computed tomography angiography (CTA) revealed tandem occlusions of the proximal left internal carotid artery (ICA) and of the distal left middle cerebral artery (MCA) with an ASPECT (Alberta Stroke Program Early CTScore) score of 6. The patient underwent a cerebral angiogram and was treated with balloon angioplasty with a distal EPD and mechanical thrombectomy. The EPD became occluded with thrombus from the ICA and was retrieved through a 6-Fr Sofia (MicroVention) under continuous aspiration. Successful revascularization of the proximal ICA and distal MCA was achieved. No procedure-related complications occurred, and the patient's neurological exam improved. Tandem occlusions can occur in up to 15% of strokes. The optimal treatment can be controversial, but mechanical thrombectomy and ICA revascularization with a distal EPD appear to be safe and effective in selected patients.3 Consent was obtained for the procedure and for the video production.

Abstract TP573: Nrf2 Activation With Sulforaphane Reduces Post-Stroke Cognitive Impairment in Mice

Introduction: Post-stroke dementia is common in stroke patients and oxidative stress may contributes to its pathogenesis. Nuclear factor erythroid 2 related factor (Nrf2) is a master transcription factor regulating the expression of a series of anti-oxidative enzymes. Sulforaphane (Sfn) is a dietary Nrf2 activator rich in cruciferous vegetables. This study aims to test our hypothesis that Sfn treatment reduces white matter injury and cognitive impairment after ischemic stroke. Methods: Adult male and female wildtype and Nrf2 knockout mice were randomly and blindly assigned into sham, vehicle, and Sfn-treatment groups (n=8-10). Stroke was induced in mice by direct coagulation of the left distal middle cerebral artery and permanent ligation of left common carotid artery occlusion. Sfn in PBS was administered by intraperitoneal injection (20 mg/kg) starting after the surgery and subsequently every other day for 5 weeks. Sensorimotor deficits were assessed using Rota-rod and foot fault tests 3-35 d and cognitive impairment were determined using Morris water maze test 29-34 d after surgery. Brain tissue loss was assessed at 35 d after surgery. In vitro, primary neuronal cultures were treated with vehicle or Sfn (1.5 μM) and chronic hypoxia/ischemia was then induced by incubation with cobalt chloride (250 μM) for 48 h. Neuronal viability was assessed with MTT assay. Results: Wildtype mice exhibited significantly sensorimotor deficits and long-term cognitive impairment after stroke. Sfn treatment alleviated these sensorimotor deficits, long-term cognitive impairment, and brain infarct size in wildtype mice. Nrf2 knockout mice also exhibited significantly sensorimotor deficits and long-term cognitive impairment after stroke; however, Sfn treatment didn’t affect these sensorimotor. In cultures, neuronal survival rate in Sfn group was significantly higher compared with vehicle group. Nrf2 knockdown with Nrf2-shRNA abolished the protective effects of Sfn. Conclusion: Sfn treatment reduces cognitive impairment after stroke in mice in a Nrf2 depended manner. Nrf2 may be a promising target to reduce post-stroke cognitive impairment.

Increased Inflammatory Response in Old Mice is Associated with More Severe Neuronal Injury at the Acute Stage of Ischemic Stroke.

Stroke occurs mostly in patients with advanced age. Elderly patients have a less favorable prognosis compared with young adult patients. To understand the underlying mechanisms, we tested our hypothesis that an increased inflammatory response to acute ischemic injury in old stroke mice leads to more severe brain damage and behavioral dysfunction. An ischemic stroke model was created in 2- and 12-month-old C57BL/6 mice through permanent occlusion of the left distal middle cerebral artery (dMCAO). Infarct/atrophy volumes were quantified by staining the brain sections with Cresyl Violet. Sensorimotor function was assessed using the corner test and adhesive removal test. Quantification of CD68+ cells in the peri-infarct region was performed at 1, 3 and 14 days after dMCAO. Interleukin-6 (IL-6), interleukin-1 β (IL-1β) and vascular endothelial growth factor (VEGF) levels in the ischemic brain tissue were measured using ELISA. Western blot was used to determine the expression levels of tight junction proteins, claudin-5 and zonula occludens (ZO)-1. Blood-brain barrier permeability was measured by Evans blue (EB) extravasation. Gelatinase B (MMP-9, type IV collagenase) was measured by gel zymography. Compared to 2-month-old mice, 12-month-old mice had more severe behavioral deficits at both the acute and chronic stages of stroke. Compared with the 2-month-old mice, 12-month-old mice had larger infarct/atrophy volumes at 1 and 14 days after dMCAO, higher levels of IL-6 and IL-1β, higher MMP9 activity, and lower levels of claudin-5 and ZO-1 at 1 and 3 days after dMCAO. 12-month-old mice also had more CD68+ cells in the peri-infarct region at 1, 3 and 14 days after dMCAO and more EB leakage at 3 days after dMCAO. A higher inflammatory response at the acute stage of ischemic stroke in old mice is associated with more severe neuronal injury and long-term behavioral dysfunction.

Abstract WP292: Insulin Resistance is Associated with a Reduction of Leukocyte Surface CD36 Expression and an Increase of Soluble CD36

Introduction: Diabetes is a major risk factor for ischemic stroke. Evidence suggests that the deficiency in CD36 is linked to insulin resistance in humans, yet patients with type 2 diabetes often display elevated plasma level of soluble CD36 (sCD36). However, cell type specific expression of CD36 is not well understood in the context of type 2 diabetes. Hypothesis: We hypothesize that insulin resistance is correlated with a reduction in the surface expression of CD36 among inflammatory cells, coincident with an increase in sCD36. Methods: Middle-aged db/db and db/+ mice (30-50 weeks-old) were subjected to left distal middle cerebral artery occlusion (dMCAO) or sham surgery. One, 3, or 7 days after stroke, leukocytes from blood and left hemisphere of the brain were analyzed by flow cytometry for cell type specific expression of CD36. The level of sCD36 in platelet free plasma was determined by ELISA. PPAR-γ agonist pioglitazone was administered at 2.5 mg/kg/day by oral gavage. Oral glucose tolerance test was performed at baseline and following two weeks of drug treatment. Both form of CD36 was also measured in 3-week-old mice without stroke. Results: Infiltrating neutrophils in brain peaked at 1 day after dMCAO, in contrast to a delayed but sustained increase of macrophages from 3 to 7 days post stroke. The adult db/db mice had a lower leukocyte surface expression of CD36 in both blood and brain, but had a higher level of sCD36 compared to age-matched db/+ mice whether at baseline or after stroke. The sCD36 is unlikely to exist in the form of extracellular vesicles (EV) since there were very few CD36(+) EVs detected in either type of mice. Prior to the development of obesity, 3-week-old db/db mice had similar leukocyte CD36 surface expression and plasma level of sCD36 compared to juvenile db/+ mice. Pioglitazone improved glucose sensitivity and enhanced macrophage CD36 surface expression in db/db mice after stroke. Conclusions: The reduced surface expression of CD36 on leukocytes and increased sCD36 was directly correlated with insulin resistance. Ongoing studies will determine the molecular event induced by obesity that triggers the cleavage of CD36 and how it affects macrophage function in the setting of diabetes.

White matter injury and microglia/macrophage polarization are strongly linked with age-related long-term deficits in neurological function after stroke

Most of the successes in experimental models of stroke have not translated well to the clinic. One potential reason for this failure is that stroke mainly afflicts the elderly and the majority of experimental stroke studies rely on data gathered from young adult animals. Therefore, in the present study we established a reliable, reproducible model of stroke with low mortality in aged (18month) male mice and contrasted their pathophysiological changes with those in young (2month) animals. To this end, mice were subjected to permanent tandem occlusion of the left distal middle cerebral artery (dMCAO) with ipsilateral common carotid artery occlusion (CCAO). Cerebral blood flow (CBF) was evaluated repeatedly during and after stroke. Reduction of CBF was more dramatic and sustained in aged mice. Aged mice exhibited more severe long-term sensorimotor deficits, as manifested by deterioration of performance in the Rotarod and hanging wire tests up to 35d after stroke. Aged mice also exhibited significantly worse long-term cognitive deficits after stroke, as measured by the Morris water maze test. Consistent with these behavioral observations, brain infarct size and neuronal tissue loss after dMCAO were significantly larger in aged mice at 2d and 14d, respectively. The young versus aged difference in neuronal tissue loss, however, did not persist until 35d after dMCAO. In contrast to the transient difference in neuronal tissue loss, we found significant and long lasting deterioration of white matter in aged animals, as revealed by the loss of myelin basic protein (MBP) staining in the striatum at 35d after dMCAO. We further examined the expression of M1 (CD16/CD32) and M2 (CD206) markers in Iba-1+ microglia by double immunofluorescent staining. In both young and aged mice, the expression of M2 markers peaked around 7d after stroke whereas the expression of M1 markers peaked around 14d after stroke, suggesting a progressive M2-to-M1 phenotype shift in both groups. However, aged mice exhibited significantly reduced M2 polarization compared to young adults. Remarkably, we discovered a strong positive correlation between favorable neurological outcomes after dMCAO and MBP levels or the number of M2 microglia/macrophages. In conclusion, our studies suggest that the distal MCAO stroke model consistently results in ischemic brain injury with long-term behavioral deficits, and is therefore suitable for the evaluation of long-term stroke outcomes. Furthermore, aged mice exhibit deterioration of functional outcomes after stroke and this deterioration is linked to white matter damage and reductions in M2 microglia/macrophage polarization.

Abstract T P77: Long-term Neuroprotection with Pharmacological Hypothermia by TRPV1 Agonism in Ischemic Stroke

Background: Therapeutic hypothermia is a promising strategy for neuroprotection following stroke. However, current widely available methods are not compatible with conscious patients and produce unwanted physiological stress. We have recently demonstrated that pharmacological hypothermia (PH) through transient receptor potential vanilloid 1 (TRPV1) channel agonism is effective and safe in the conscious mouse and provides significant neuroprotection following ischemic stroke at 24 hours reperfusion. We now evaluate whether this method of PH provides sustained neuroprotection through one month reperfusion. Methods: Three experimental groups were evaluated: sham operated (Sham), stroke with normothermia (Stroke/NT), and stroke with PH (Stroke/PH) (n=8, 10, 7). Stroke was induced by transient occlusion of left distal middle cerebral artery (MCA) plus left common carotid artery for two hours. For the Stroke/PH group, hypothermia (32-34°C) was induced by infusion of TRPV1 agonist (dihydrocapsaicin) for 8 hours; beginning 90 minutes after reperfusion. We evaluated several behavioral tests from pre-stroke up to 28 days reperfusion. Total cerebral infarct was then evaluated in Nissl-stained brain sections at 30 days reperfusion. Results: The foot fault test was the most sensitive in demonstrating extended functional deficit after stroke. With this test, Stroke/NT demonstrated prolonged deficiency (through 21 days reperfusion) compared to Sham. PH treatment (Stroke/PH) demonstrated significant improvement in function compared to Stroke/NT. Other tests demonstrated non-statistically significant performance reduction of Stroke/NT in swimming time, grip side preference, turning and climbing time. Histological analysis demonstrated significant ipsilateral necrosis and hemisphere shrinkage in Stroke/NT brains compared to Stroke/PH brains. Conclusions: In summary, we demonstrate long-term neuroprotection with TRPV1-mediated PH following stroke. These studies support the therapeutic potential of TRPV1 agonism for promoting hypothermia in the conscious stroke subject.

A case of delayed neurological recovery with luxury perfusion and a high intracranial arterial calcification burden.

Dear Sir, Although patients with acute ischemic stroke achieve recanalization, approximately 37%-65% of them do not show immediate improvement.1 The term stunned brain refers to delayed neurological recovery after an ischemic insult to the brain.1 We describe the case of a patient with delayed neurological recovery who had a small cerebral infarction but relatively rapid compensatory perfusion and high calcification burden in the intracranial arteries. A 71-year-old woman visited our emergency room 1.5 hours after developing acute right limb weakness. The initial neurological examination revealed right hemiplegia (arm and leg, grade 2 on the Medical Research Council grading system) and global aphasia (National Institutes of Health Stroke Scale score, 22). Non-enhanced computed tomography did not reveal a definite ischemic or hemorrhagic lesion, and intravenous recombinant tissue plasminogen activator was subsequently infused. Computed tomography angiography revealed a moderate degree of stenosis in the left middle cerebral artery (Figure 1A) and a high calcification burden in almost all intracranial arteries (Figure 1A, B). We assumed that an occlusion of the middle cerebral artery might be in the process of recanalization. Immediate magnetic resonance imaging revealed a small acute infarction near the posterior pole of the lateral ventricle on diffusion-weighted imaging (Figure 1C). Perfusion magnetic resonance imaging performed simultaneously revealed luxury perfusion in the left posterior temporo-parieto-occipital area (Figure 1D). Although her neurological symptoms had improved 24 hours after onset, she still had right hemiparesis (arm and leg, grade 4) and dense sensory aphasia (National Institutes of Health Stroke Scale score, 8). The localization of these neurological deficits corresponded to the area of luxury perfusion. On the fourth day after admission, the small lesion persisted on diffusion-weighted imaging (Figure 1E), and the luxury perfusion had normalized (Figure 1F), but the neurological deficits including sensory aphasia remained (National Institutes of Health Stroke Scale score, 7). By the sixth day after admission, her neurological deficits had completely disappeared. Figure 1 Initial computed tomography (CT) and magnetic resonance (MR) images of the patient in this study. (A) A coronal maximum intensity projection image from CT angiography shows significant stenosis of the distal left middle cerebral artery, which was lined ... The patient showed some immediate neurological recovery, but sensory aphasia persisted even though the diffusion-restricted lesion was small and the cerebral perfusion pattern was compensatory. We propose that this delayed neurological recovery was associated with vascular aging, which was reflected by the high intracranial arterial calcification burden. Calcium deposition in the vasculature is one of the main components of vascular aging,2 which is associated with poor adaptation following ischemia/reperfusion injuries.3 In addition, neovascularization following reperfusion is hampered by the vascular calcification process.4 Reperfusion may result in increased levels of reactive oxygen species that subsequently impair endothelial progenitor cell function.5 With regard to post-stroke repair mechanisms, endothelial progenitor cells are known to be essential for neovascularization.6,7 The delayed neurological recovery could be explained by these poor adaptations and hampered neovascularization following revascularization. The delayed neurological recovery in this patient could also have been associated with the luxury perfusion phenomenon; however, a previous report has shown a relationship with perfusion deficit. Hyperperfusion on perfusion magnetic resonance imaging is thought to reflect a high degree of ischemic stress.8 The hyperperfused area was reported to correspond to the area of cerebral infarction in this patient. When compared to patients with normal perfusion, those with hyperperfusion show lower apparent diffusion coefficient values.8 Moreover, delayed clinical recovery has been reported to be associated with perfusion deficits.1 A defect that extends beyond a diffusion-restricted area is referred to as an ischemic penumbra,9 which exhibits deranged cerebral metabolism and can be identified using perfusion imaging. The present case indicates that either hyperperfusion or hypoperfusion may be associated with delayed neurological recovery after cerebral arterial recanalization.8 In conclusion, the delayed neurological recovery observed in our patient might have resulted from either post-ischemic reperfusion syndrome associated with luxury perfusion, or an impaired post-stroke repair mechanism associated with a high burden of intracranial arterial calcification. Computed tomography and magnetic resonance imaging are both useful for estimating the degree of ischemic injury.

Ruptured Mycotic Aneurysm of the Distal Middle Cerebral Artery Manifesting as Subacute Subdural Hematoma

Mycotic aneurysms are rare inflammatory neurovascular lesions. Ruptured mycotic aneurysm manifesting as subdural hematoma is extremely rare. A 72-year-old male patient was admitted to our hospital with headache and drowsiness. Computer tomography (CT) of brain and CT angiography revealed subdural hematoma and an aneurysm located at the M4 segment of the left middle cerebral artery (MCA). Cerebral angiogram revealed 2 aneurysms; one located at the left distal MCA and the other at the bifurcation of left MCA. Laboratory studies showed leukocytosis and elevated inflammatory factors. The patent was treated with antibiotic therapy for 4 weeks. The follow-up CT and cerebral angiography showed that the mycotic aneurysm was completely resolved, and the patient was nearly free of symptoms.

Ischemic Postconditioning Fails to Protect against Neonatal Cerebral Stroke

The lack of efficient neuroprotective strategies for neonatal stroke could be ascribed to pathogenic ischemic processes differentiating adults and neonates. We explored this hypothesis using a rat model of neonatal ischemia induced by permanent occlusion of the left distal middle cerebral artery combined with 50 min of occlusion of both common carotid arteries (CCA). Postconditioning was performed by repetitive brief release and occlusion (30 s, 1 and/or 5 min) of CCA after 50 min of CCA occlusion. Alternative reperfusion was generated by controlled release of the bilateral CCA occlusion. Blood-flow velocities in the left internal carotid artery were measured using color-coded pulsed Doppler ultrasound imaging. Cortical perfusion was measured using laser Doppler. Cerebrovascular vasoreactivity was evaluated after inhalation with the hypercapnic gas or inhaled nitric oxide (NO). Whatever the type of serial mechanical interruptions of blood flow at reperfusion, postconditioning did not reduce infarct volume after 72 hours. A gradual perfusion was found during early re-flow both in the left internal carotid artery and in the cortical penumbra. The absence of acute hyperemia during early CCA re-flow, and the lack of NO-dependent vasoreactivity in P7 rat brain could in part explain the inefficiency of ischemic postconditioning after ischemia-reperfusion.

307 Effects of the Ischemic Postconditioning in A Neonatal Stroke Model

The lack of efficient neuroprotective strategies for neonatal stroke could be ascribed to pathogenic ischemic processes differentiating adults and neonates. In the present study, we tested the hypothesis that ischemic...

Abstract 3190: Increased Inflammatory Response in Aged Mice is Associated with More Severe Neuronal Injury at the Acute Stage of Ischemic Stroke

Background and Purpose: Stroke occurs mostly in patients with advanced age and older patients have a less favorable prognosis than younger patients. To understand the underlying mechanisms involved in this phenomenon, we tested the hypothesis that an increased inflammatory response to acute ischemic injury in the aged mice leads to more severe brain damage and functional deficits. Methods: An ischemic stroke model was created in two- (young) and twelve-month-old (aged) C57BL/6 mice (n=6) through permanent occlusion of the left distal middle cerebral artery (pMCAO). Infarct volumes in the brain sections were quantified at one day after pMCAO by Cresyl Violet staining. Sensorimotor function was assessed using corner test and adhesive removal test before, 3, and 14 days after pMCAO. Macrophage/microglia (CD68+ cells) and apoptotic neurons (TUNEL+ and NeuN+) in the ischemic region were quantified one day after pMCAO. The interleukin-6 (IL-6) and interleukin-1 β (IL-1β) levels in the ischemic brain tissue were measured using ELISA at one and three days after pMCAO. Results: At one day post pMCAO, infarct volume was larger in aged mice than in young mice (31±3/mm3 vs 27±5, p= 0.05), Comparing aged mice to young mice, more TUNEL+ neurons (22±5 vs 15±5, p=0.04) were detected in the infarct region. Both young and aged mice showed significant sensorimotor dysfunction on day 3 and 14 post pMCAO; turning more frequently to the left on the corner test and taking longer time to remove tape on left paws. More severe functional deficits were detected on aged mice by adhesive removal test at day 14 post pMCAO (12±5 seconds vs 6±3, p=0.01, aged vs young). There were more CD68+ cells in the peri-infarct region in aged mice compared to young mice (79±22/ 40X objective field vs 58±18, p=0.01). Infarct volume was positively correlated with both the numbers of CD68+ cells (R2= 0.80) and TUNEL+ neurons (R2= 0.86). Compared to young, cytokine levels also increased in aged mice at one day (IL-6: 308 ±152 pg/mg vs 147±44, p=0.03; IL-1β: 96±35 vs 55±8, p=0.02) and three days (IL-6: 149 ±53 vs 90±27, p=0.03; IL-1β: 55 ±14 vs 38± 5, p= 0.02) after pMCAO. Conclusion: Our data suggest that a higher inflammatory response at the acute stage of ischemic stroke in aged mice is associated with more severe neuronal injury (larger infarct volume and more apoptotic neurons) and long-term functional deficits. The upstream mechanisms responsible for the enhanced response will require additional studies. However, modulating inflammatory response in the aged population at the acute stage might be a strategy to reduce neuronal injury and improve functional recovery in older stroke patients with monitoring of brain inflammation a feasible means of risk stratification.

In Vivo Real-Time Multiphoton Imaging of T Lymphocytes in the Mouse Brain After Experimental Stroke

To gain a better understanding of T cell behavior after stroke, we have developed real-time in vivo brain imaging of T cells by multiphoton microscopy after middle cerebral artery occlusion. Adult male hCD2-GFP transgenic mice that exhibit green fluorescent protein-labeled T cells underwent permanent left distal middle cerebral artery occlusion by electrocoagulation (n=6) or sham surgery (n=6) and then multiphoton laser imaging 72 hours later. Extravasated T cell number significantly increased after middle cerebral artery occlusion versus sham. Two T cell populations existed after middle cerebral artery occlusion, possibly driven by 2 T cell subpopulations; 1 had significantly lower and the other significantly higher track velocity and displacement rate than sham. The different motilities and behaviors of T cells observed using our imaging approach after stroke could reveal important mechanisms of immune surveillance for future therapeutic exploitations.

Temporary Test Occlusion of Distal Middle Cerebral Artery Using GDC Coil

The treatment of small distal intracranial aneurysms often requires parent vessel occlusion. However, this may be particularly challenging in patients in which the parent vessel serves eloquent brain. Superselective amytal testing is often conducted in these cases, but may prove unreliable or inconclusive. In order to more specifically assess the functional significance of the parent vessel in this patient with a distal left middle cerebral artery pseudoaneurysm who had failed superselective amytal testing, we used a Guglielmi Detachable coil to perform a temporary test occlusion. Testing was performed with the patient awake and examinable, and after no neurological changes were noted, the vessel was permanently occluded, successfully treating the aneurysm. To our knowledge, this is the first report to describe this unique method for assessing a parent vessel that previously had been thought to supply eloquent brain during amytal testing.

The Akt Pathway Is Involved in Rapid Ischemic Tolerance in Focal Ischemia in Rats

Although the protective mechanisms of delayed ischemic preconditioning have received extensive studies, few have addressed the mechanisms associated with rapid ischemic postconditioning. We investigated whether ischemic tolerance induced by rapid preconditioning is regulated by the Akt survival signaling pathway. Stroke was generated by permanent occlusion of the left distal middle cerebral artery (MCA) plus 30 min or 1 h occlusion of the bilateral common carotid artery (CCA) in male rats. Rapid preconditioning performed 1h before stroke onset reduced infarct size by 69% in rats with 30 min CCA occlusion, but by only 19% with 1 h occlusion. After control ischemia with 30 min CCA occlusion, Western Blot showed that P-Akt was transiently increased while Akt kinase assay showed that Akt activity was decreased. Although preconditioning did not change P-Akt levels at 1h and 5h compared with control ischemia, it attenuated reduction in Akt activity at 5h in the penumbra. However, preconditioning did not change the levels of P-PDK1, P-PTEN, and P-GSK3β in the Akt pathway, all of which were decreased after stroke. At last, the PI3K kinase inhibitor, LY294002, completely reversed the protection from ischemic preconditioning. In conclusion, Akt contributes to the protection of rapid preconditionin against stroke.

Advances in imaging of new targets for pharmacological intervention in stroke: real‐time tracking of T‐cells in the ischaemic brain

T-cells may play a role in the evolution of ischaemic damage and repair, but the ability to image these cells in the living brain after a stroke has been limited. We aim to extend the technique of real-time in situ brain imaging of T-cells, previously shown in models of immunological diseases, to models of experimental stroke. Male C57BL6 mice (6-8 weeks) (n= 3) received a total of 2-5 x 10(6) carboxyfluorescein diacetate succinimidyl ester (CFSE)-labelled lymphocytes from donor C57BL6 mice via i.v. injection by adoptive transfer. Twenty-four hours later, recipient mice underwent permanent left distal middle cerebral artery occlusion (MCAO) by electrocoagulation or by sham surgery under isoflurane anaesthesia. Female hCD2-green fluorescent protein (GFP) transgenic mice that exhibit GFP-labelled T-cells underwent MCAO. At 24 or 48 h post-MCAO, a sagittal brain slice (1500 microm thick) containing cortical branches of the occluded middle cerebral artery (MCA) was dissected and used for multiphoton laser scanning microscopy (MPLSM). Our results provide direct observations for the first time of dynamic T-cell behaviour in living brain tissue in real time and herein proved the feasibility of MPLSM for ex vivo live imaging of immune response after experimental stroke. It is hoped that these advances in the imaging of immune cells will provide information that can be harnessed to a therapeutic advantage.

Delayed treatment for a case of acute ischaemic stroke using mechanical embolectomy — the L5 Merci Retriever

AbstractEndovascular therapies for acute ischaemic stroke represent important alternatives or adjuncts to thrombolysis. A middle‐aged male suffered a Thrombolysis in Myocardial Infarction (TIMI) Grade 0 distal left middle cerebral artery (LMCA) occlusion resulting in right hemiparesis and dysphasia. Intravenous thrombolysis was contraindicated due to pre‐existing anticoagulant therapy and associated risk of intracranial haemorrhage. The patient underwent rescue mechanical embolectomy with an L5 Merci Retriever, with adjuvant local intra‐arterial (IA) thrombolysis. Successful TIMI Grade 3 restoration of LMCA blood flow occurred within eight hours of ictus. Aphasia resolved within 24 hours, whilst other motor and speech symptoms gradually improved over 6 months, allowing the patient to resume work and independent living. Mechanical embolectomy appears to be a safe and effective alternative in cases of delayed presentation, or where intravenous thrombolysis is contraindicated. Combined mechanical embolectomy and adjuvant IA thrombolysis, instituted within eight hours of ictus in an anticoagulated patient, achieved favourable clinical outcome (modified Rankin Score of 2) without major thromboembolic or haemorrhagic complications.

Limb remote ischemic postconditioning protects against focal ischemia in rats

Remote ischemic postconditioning (RIP) refers to an ischemia conducted in a distant organ that protects against a prior ischemia in another organ. We tested whether RIP protects against focal ischemia in the rat brain. Stroke was generated by a permanent occlusion of the left distal middle cerebral artery combined with a 30-min occlusion of the bilateral common carotid arteries (CCA) in male rats. After CCA release, RIP was generated by three cycles of 15-min occlusion/15-min release of the left-hind femoral artery. The results showed that rapid RIP performed immediately after CCA release reduced infarction by 67% measured at 2 days after stroke. In addition, delayed RIP initiated as late as 3 h, but not 6 h, still robustly reduced infarction by 43% 2 days after stroke. RIP's protective effect was abolished by injecting the protein synthesis inhibitor, cycloheximide, and the afferent nerve blocker, capsaicin, suggesting that RIP blocks ischemic injury by modulating protein synthesis and nerve activity. Nevertheless, rapid RIP did not reduce infarction size 2 months after stroke while it ameliorated the outcome of the behavioral test. In conclusion, RIP attenuates brain injury after focal ischemia.

Ultrasonic Assessment of Cerebral Blood Flow Changes During Ischemia-Reperfusion in 7-Day-Old Rats

A model of ischemic brain injury in 7-day-old rat pups has been developed to study perinatal ischemia. It combines permanent occlusion of the distal left middle cerebral artery (LMCA) and transient occlusion of homolateral common carotid artery (LCCA). At removal of the clip on LCCA, reflow allowed brain reperfusion through cortical anastomoses. In 10 rat pups, we measured blood flow velocities (BFV) in main cerebral arteries with 12-MHz ultrasound imaging. At basal states, peak systolic BFV in proximal LMCA was 16.0 ± 3.0 cm.s –1. Occlusion of LMCA did not yield significant modifications. Occlusion of LCCA involved only a decrease in BFV to 9.5 ± 2.6 cm.s –1 ( p < 0.001). Indeed, LMCA was then supply by the right internal carotid and the vertebral arteries through the circle of Willis. In three rat pups, release of occlusion of LCCA was followed by restoration of BFV in the left internal carotid artery and in LMCA, in seven pups, by a reversed flow in the LICA and lower BFV in LMCA (11.9 ± 2.3, p < 0.05). BFV returned to basal values from h5 to h48 in all animals. In addition, ultrasound imaging is a useful, reproducible, non invasive, easy-to-repeat, method to assess and monitor arterial cerebral blood flow supply in small animals. It helps to characterize changes occurring during cerebral ischemia and reperfusion, particularly the depth of the hypoperfusion, as well as the variability of reflow. In preclinical studies, this method could help to identify what can be assigned to a neuroprotective treatment and what depends on changes in cerebral blood flow supply. (E-mail: philippe.bonnin@lrb.aphp.fr)