Cerebral Artery Occlusion Research Articles

Abstract W P209: Development of a Useful Brain Ischemic Stroke Model via a Transient Occlusion of Middle Cerebral Artery in the Nonhuman Primate

Objectives: Most experimental stroke research is carried out in rodents, but given differences between rodents and human, the nonhuman primate (NHP) models may provide a valuable tool to study the clinical therapy. We developed a surgical method for transient occlusion of the middle cerebral artery (MCA-M1) in the Cynomolgus monkeys to evaluate the MCA territory blood flow, the model stability, animal clinical neurological behavior, morphology changes under magnetic resonance imaging (MRI) and histopathology. Methods: The left brain sylvian fissure was exposed by a small fronto-temporal craniotomy. The MCA-M1 was exposed by microsurgical dissection and clipped for 4 hours. The brain blood flow was measured in the MCA territory during the ischemia period and early phase of reperfusion period. The clinical neurological examinations and MRI were carried out at regular post-operative course till 4 weeks of stroke. Results: During MCA occlusion, the MCA territory blood flow was decreased significantly in 80%. This territory was reflowed right after reperfusion and showed an overload in about 20% over pre ischemia flow within 1hr after reperfusion and gradually returned to previous flow (Fig 1). Animal neurological behavior changed significantly within 1 week and became a steady status of neurological impairment. MRI demonstrated extensive MCA territory infarction. Histologically, at the end of 4 week stroke the brain showed a clear board of glia proliferation between infarct and normal brain tissue. Conclusion: These results indicate a stable ischemic stroke model in cynomolgus monkeys after complete MCA-M1 occlusion, which will be a useful NHP stroke model for stroke research and the clinical therapeutic studies. Fig 1 Changes in MCA territory blood flow during ischemia-reperfusion period

Abstract T P218: Peripheral Organ Proteomics, a Novel Approach to Biomarker Discovery for Brain Disorders

Introduction: Brain disorders may produce changes in function of peripheral organs. The lack of omics characterization of peripheral organs hinders development of novel approaches for diagnosing/managing brain disorders. We have characterized proteomes of ischemic brain injury (Stapels et al., 2010, Science Signaling 3 (111):ra15). Here, we demonstrate: 1) Acute brain disorders induce systemic responses in peripheral proteomes; 2) Brain disorder-induced peripheral proteomic changes are specific to injury conditions. Renal proteomic responses to focal brain ischemia are examples. Methods Ischemia: suture occlusion (30 or 60 minutes: n=5, sham: n=4) of middle cerebral artery (MCAO) in mice. After 4 hours reperfusion, brain cortices and one kidney were removed at sacrifice. Proteins were extracted from individual tissues. Tryptic digests from animals of the same experimental group were pooled, and analyzed by quantitative mass spectrometry with triplicate replications. Proteins showing differences in abundance between sham and 30 minutes or 60 minutes brain ischemia were further analyzed by bioinformatics. Results and Conclusion: At 4 hours after 30 or 60 minutes MCAO, kidney proteome showed significant changes compared to that of sham controls: 72 and 56 proteins with increased abundance in the former and latter brain conditions, respectively. Interestingly, among up-regulated proteins, only 24 showed an overlap between the 30 and 60 minute brain ischemic conditions. Results of bioinformatic analyses of regulated kidney proteins indicated an association with cellular pathways or processes of cell adhesion, small molecule metabolism, protein folding, as well as immune response, for both brain ischemic conditions. Differential changes were also observed: an increase of amino acid metabolism and nucleoside catabolic processes were detected only in 60 but not 30 minutes brain ischemic conditions. Our previous work has shown that 30 minutes MCAO results in very limited cortical injury whereas 60 minutes MCAO leads to broad tissue infarction. Hence, our results present distinguishable kidney proteomic characteristics associated with different brain ischemic conditions.

Abstract W P199: Deficiency of Glia Maturation Factor Abrogates Brain Injury and Inflammation in a Murine Model of Stroke

Background and purpose: Glia maturation factor (GMF), a brain specific protein, discovered and characterized in our laboratory, induces expression of proinflammatory cytokines/ chemokines in the central nervous system (CNS). Recently, it has been demonstrated that deficiency of GMF mitigates neuronal damage in tissue culture cell and animal models of neurodegeneration. Since, GMF expression in brain enhances inflammation; we tested the hypothesis that deficiency of GMF abrogates the inflammatory responses in experimental model of ischemic stroke. Methods: Transient focal cerebral ischemia was induced by 1 hour of occlusion of the right middle cerebral artery (MCAO) with a 7.0 monofilament in GMF-containing wild type (Wt) and GMF-deficient (GMF-KO) mice. Mice were anesthetized with 1-1.5% isoflurane mixed with medical oxygen. Body temperature was maintained at 37°C ± 1.0 using a heating pad. At 23 hours after ischemia/reperfusion, mice were tested for neurological scores and were sacrificed for the infarct volume and estimation of inflammatory responses. Immunohistochemistry and western blots were used to analyze the expression and activation of glial cells, and levels of NF-κB in ischemic brain hemisphere. Results: We found that levels of GMF significantly increased in MCAO mice compared to saline treated control mice. Next we found that GMF-KO mice exhibited significantly decreased infarct volume, and reduced neurological deficits compared to Wt mice. The decrease in infarct volume and neurological deficits in GMF-KO mice were correlated with a less activation of glia cells, downregulation of NF-κB and suppression of proinflammatory cytokines/chemokine in the ischemic region. Conclusions: In conclusion, present study provides the first evidence that deficiency of GMF reduces brain injury and inflammation after ischemic stroke and suggests that the effective suppression of endogenous GMF-function will prove to be an effective and selective strategy to slow deleterious inflammatory processes in ischemic brain injury. Keywords: Glia maturation factor; Ischemic stroke; Inflammation; Nuclear factor-κB; Cytokines

Abstract W P95: Assessment of the Optimal Cell Number for the Trans-arterial Transplantation after Stroke in Rat

Introduction and Purpose: Recently, cell transplantation have emerged as a promising treatment option for cerebral infarction in various kinds of animal models. However, optimal conditions (cell number, timing of cell transplantation, optimal route of delivery, best source of cells) remain unknown. The aim of this study was to clarify the optimal cell number for trans-arterial transplantation after stroke. Methods: Male Sprague-Dawley rats were subjected to an intraluminal occlusion of the middle cerebral artery (75 min.). At 24 hours post-stroke, we transplanted human mesenchymal stem cells (hMSCs) via carotid artery. The animals were divided into three groups, 1х10 6 hMSCs transplantation (n=8), 1х10 6 hMSCs transplantation (n=8) , and vehicle (n=8). Neurological recovery was assessed using modified neurological severity score (mNSS) and cylinder tests at day 0, 1, 2, 5 and 9 post-stroke in addition to body weight, lesion size, immune response, and hMSC distribution. Results: Rats treated with 1х10 6 hMSCs improved neurological recovery at day 5 (P<0.05), and day 9 post-stroke (P<0.05). Moreover, rats treated with 1х10 6 hMSCs cells showed further improvement at day 5 (P<0.01), and day 9 (P<0.05) compared with vehicle group. Transplantation of hMSCs (1х10 4 ,1х10 6 ) significantly showed less body weight loss at day 8 and 9 post-stroke (P<0.01), and revealed smaller lesion size at day 9 post-stroke (P<0.05). Interestingly, hMSC treated (1х10 4 , 1х10 6 ) animals showed better engraftment of cells in the peri-infarct area, where immune response was significantly supressed (P<0.05). Conclusion: We found that trans-arterial transplantation with small amount of hMSCs could be sufficient to show functional recovery after stroke. These findings provide new information about optimizing cell number in trans-arterial transplantation after stroke, which is much beneficial especially for autologous transplantation.

Abstract T P225: cGMP-Dependent Protein Kinase I in Smooth Muscle Cells Protects Against Stroke Injury in Mice

The signaling pathways by which NO protects against stroke injury are mediated by cyclic guanosine monophosphate (cGMP) formation. However, the mechanisms of downstream signaling from cGMP to smooth muscle cells (SMC) remain incompletely understood. The cGMP-dependent protein kinase I (cGKI) is a key mediator of cGMP signaling. The goal of this study is to test the hypothesis that cGKI in SMC protects against stroke injury. Animals: We used the novel mouse line for highly efficient tamoxifen-inducible SMC-specific gene knockout, SMA-CreERT2, which expresses the CreERT2 recombinase under the control of the smooth muscle alpha-actin promoter (cGKI KO mice). The litter mate wild-type (WT) mice (no Cre gene) receiving the same tamoxifen treatment were used as control (cGKI WT) mice. Methods and Results: Mean blood pressure measured acutely from the common carotid artery under anesthesia (30% oxygen, 70% nitrous oxide and 1.5% isoflurane) was higher in cGKI KO mice (107±8 mmHg, Mean±SD) than in cGKI WT mice (95±1 mmHg, n=4/group, P<0.05). One hour of middle cerebral artery (MCA) occlusion by filament with 23 hours of reperfusion produced increased cerebral infarct volume (TTC staining, indirect calculation) in cGKI KO mice (123±39 mm3) as compared with cGKI WT (85±17 mm3, n=5/group, p< 0.05). Neurological deficit by 5 point scale was worse in cGKI KO mice (4.0 points) as compared with cGKI WT (2.4 points). Cerebral blood flow monitored by laser Doppler flowmetry above the core of the MCA territory indicated that reperfusion was less in cGKI KO mice than in cGKI WT mice, suggesting that cGKI mediates cerebrovascular SMC relaxation and protects against ischemic stroke. Vascular relaxation of mesenteric resistance arteries to acetylcholine, and the NO donor, NONOate after preconstriction with phenylephrine was dramatically impaired in cGKI KO mice. It suggests the importance of cGKI in the vascular SMC for NO-induced relaxation. In conclusion, stroke injury was more pronounced in cGKI SMC specific inducible conditional knockout mice than in cGKI WT mice, suggesting a protective role for cGKI in SMC against cerebral reperfusion injury. These studies identify the cGKI in cerebral vasculature as a potential target for therapies aimed at reducing stroke injury.

Abstract W P213: Leptomeningeal Collateral Growth Is Impaired in Type 2 Diabetic Mice.

BACKGROUND: Leptomeningeal anastomoses are the most important collateral pathways, especially after middle cerebral artery (MCA) occlusion, and determine the severity of subsequent ischemic injury of the brain. We previously reported that hypertension impairs leptomeningeal arteriogenesis. Diabetes is also a major vascular risk factor and increases stroke incidence. We hypothesized that arteriogenesis of leptomeningeal anastomoses is also impaired in diabetes. METHODS: Male BKS.Cg-m+/+Leprdb/J (db/db) and the non-diabetic and lean heterozygote littermates(db/+) were used. To investigate the influence of hyperglycemia itself, male C57BL/6 mice injected with streptozotocin(STZ,250mg/kg) intraperitoneally 1week before surgery were also used. All types of mice were assigned to the left common carotid artery occlusion(CCAO) group and the sham CCAO group. After 14 days of the surgery, latex perfusion was performed to visualize the leptomeningeal anastomoses and mesure the vessel diameters(n=5, each group), or the left MCA was occluded using electrocoagulation to evaluate the infarct size with TTC staining(n=7, each group). RESULTS: In db/+ mice, there were significant increase of leptomeningeal collateral vessel diameters in response to CCAO(CCAO,33.7±1.2μm vs. sham,26.5±1.0μm, P<0.01) and infarct size was significantly attenuated, especially in the cerebral cortex, in the CCAO group compared with the sham group, which was in agreement with our previous study in normal rodents. In contrast, in db/db mice, there were no significant differences in the vessel diameters between the CCAO group and the sham group(27.9±1.0μm vs.26.6±1.0μm) and no reductive effect of infarct size attribute to leptomeningeal arteriogenesis. In STZ induced diabetic mice, there were significant increase of the vessel diameters(29.1±1.1μm vs. 23.6±0.7μm, P<0.01) and significant reduction of infarct size in response to CCAO. CONCLUSIONS: Arteriogenesis of leptomeningeal anastomoses is impaired in db/db mice, but is not impaired in STZ induced diabetic mice. These results suggest that the mechanism of impairment of arteriogenesis is not due to only hyperglycemia.

Abstract 196: Human Recombinant Peptide (RCP) Sponge Enables Novel Noninvasive Cell Therapy for Ischemic Stroke

Background: The bone marrow stromal cells (BMSCs) have the potential to improve neurologic function when transplanted into animal models of ischemic stroke. However, it is unclear through which route the BMSC should be delivered to yield the maximal therapeutic benefits safely. Using genetic engineering technique, the authors have developed the recombinant peptide (RCP) sponge of human collagen. Therefore, this study was aimed to assess whether the RCP sponge of human collagen could act as a noninvasive, valuable scaffold in cell therapy for ischemic stroke. Methods: The BMSCs were harvested from GFP-transgenic rats and were cultured in the RCP sponge. The rats were subjected to permanent middle cerebral artery (MCA) occlusion. Vehicle, BMSC suspension, or the BMSC-RCP sponge construct was transplanted onto the ipsilateral intact neocortex at 7 days after the insult. Motor function was serially evaluated throughout the experiments. The distribution and fate of engrafted cells were examined at 6 weeks after BMSC transplantation. Results: The BMSCs proliferated in the RCP sponge in vitro. Transplantation of BMSC suspension or the BMSC-RCP sponge construct equally promoted functional recovery, when compared with the vehicle group. RCP sponge provoked no inflammatory reactions in the host brain. Histological analysis revealed that the BMSC migrated and differentiated into the neural cells in the infarct brain when transplanted using the RCP sponge. Conclusion: These findings suggest that surgical transplantation of tissue-engineered BMSC onto the infarct neocortex may enhance functional recovery. RCP sponge can be a promising candidate for the animal protein-free scaffolds in cell therapy for ischemic stroke.

Abstract T P217: Neuroprotective Effects of Cilostazol through the Multi-mechanisms in Mice Permanent Focal Ischemia

Background and Purpose: It has been reported that Cilostazol, which is phosphodiesterase (PDE) 3 inhibitor clinically used as an antiplatelet drug, could ameliorate ischemic brain injury, but the mechanisms were not clarified. We aimed to investigate how Cilostazol affected mice permanent focal ischemia model. Methods: Male Balb/c mice were subjected to permanent middle cerebral artery (MCA) occlusion. They were treated with Cilostazol (10- mg/kg or 20- mg/kg) or vehicle 30 min and 24 h post-ischemia. Infarct volume was assessed by 2,3,5-triphenyltetrazolium chloride (TTC) method after 48 h (n=8 in each group). In histological analysis, the animals were sacrificed 6 h or 24 h post-ischemia (n=5 in each group), and then the immunohistochemistry was performed to the brain sections. Results: We showed that the treatment with Cilostazol salvaged the tissue damage in the infarct rim in a dose-dependent manner, and 20- mg/kg Cilostazol significantly reduced infarct volume to 70.1±24.4% of the control (P<0.05). Immunoreaction for 8-Hydroxydeoxyguanosine (OHdG), an oxidative stress marker, showed the neuronal damage by oxidative stress in peri-infarct, and the treatment with Cilostazol reduced the ratio of the damaged neurons 6 h post-ischemia (65.8±33.5% in vehicle-treated animals, 21.3±9.9% in Cilostazol-treated ones, P<0.05). Double staining for 8-OHdG and von Willebrand factor also showed that Cilostazol attenuated oxidative stress on the endothelial cells in peri-infarct 24 h post-ischemia, significantly (P<0.01). On the other hand, the immunostaining for phosphorylated cAMP response element binding protein (pCREB) showed that Cilostazol increased the ratio of the pCREB-positive neurons in peri-infarct 24 h post-ischemia significantly (74.5±8.0% in vehicle-treated animals, 93.6±2.9% in Cilostazol-treated ones, P<0.01). Conclusions: These findings suggested that Cilostazol could have multi-mechanisms to ameliorate tissue damage due to permanent focal cerebral ischemia. Thus, one is to attenuate oxidative stress on neurnons and endothelial cells in the infarct rim, and another is to protect neural damage with anti-apoptotic effect through the pathway of Akt/pCREB.

Abstract W P369: Inhibitory Effect of FTY720 on Neuroinflammation in Cerebral Ischemia-reperfusion

Background: Neuroinflammation is a key contributor to brain injury in cerebral ischemia-reperfusion (CIR). FTY720 has been shown to be neuroprotective in animal stroke models. In most studies, FTY720 treatment was initiated either before or shortly after the cerebral insult. The goal of this study is to investigate the effect of FTY720 on CIR-associated neuroinflammation and outcome using a therapeutic window similar to the one utilized in clinical practice. Methods: We used the rat middle cerebral artery (MCA) occlusion model for CIR. The right MCA was occluded for 1h followed by reperfusion. Animals were treated with vehicle or 0.5 mg/kg FTY720 intraperitoneally at 3h post-reperfusion. Neurobehavioral test battery (scale from 0 to 21 points with lower scores representing increased neurological deficits), grid-walking test, infarct volume, and brain water content were determined 24h post CIR. A cranial window was established at 24h post occlusion and leukocyte trafficking behavior was monitored by direct microscopic observation of surface venules. Pial venular leukocyte adhesion was expressed as the % of vascular area occupied by adherent rhodamine-6G-labeled leukocytes. Statistical analysis was performed by t test. Results: Compared to the vehicle group (n=10), FTY720 animals (n=10) had improved neurological score (8.6±1.9 vs. 13.7±1.9; p<0.001) and better motor performance throughout all subsections of the grid test (p<0.001). FTY720 treatment also decreased infarct volume (vehicle: 342±182; FTY720: 122±138 mm 3 ; p=0.04) and ipsilateral brain edema, measured as water content (vehicle: 84.5±1.05%; FTY720: 79.4±0.87%, p=0.003). Leukocyte trafficking study showed a significant increase in vascular leukocyte adhesion 24 h post reperfusion in the vehicle group which was markedly decreased by FTY720 treatment (sham: 3.0±0.6%; vehicle: 11.4±2.6%; FTY720: 5.2±1.4%; p<0.001). Conclusion: FTY720 given at 3h post reperfusion reduces infarct volume, brain edema, neurological disability, and vascular leukocyte adhesion. These results support the beneficial effect of FTY720 when used in a clinically relevant timeframe and provides direct evidence of the anti-inflammatory effect of FTY720 on CIR.

Abstract W MP83: Transcutaneous Vagus Nerve Stimulation for Treatment of Acute Cerebral Ischemia in Rats

Introduction: Direct electrical stimulation of the vagus nerve in the neck using surgically implanted electrodes reduces infarct volume in rats. But the invasive nature of the direct stimulation makes it impractical in acute human stroke. We tested the effect of various non-invasive or minimally invasive vagus nerve stimulation (VNS) techniques on infarct size, physiological parameters, and clinical outcome after transient middle cerebral artery (MCA) occlusion in rats. Methods: We induced cerebral ischemia by filament occlusion of the right MCA for 2h, followed by reperfusion in adult male spontaneously hypertensive rats (n=52). We performed: (1) auricular transcutaneous VNS (atVNS) via application of a microelectrode array to the auricular concha, (2) cervical transcutaneous VNS via application of HNS12 transcutaneous nerve stimulator (ctVNS-1) and Gammacore non-invasive cervical vagus nerve stimulator (ctVNS-2) put on to the skin overlying the vagus nerve in the neck. We applied tVNS for 1h starting 30 min after the induction of ischemia. We measured neurological deficit daily; at the end of 1 week we euthanized the animals to determine cerebral infarct volume. In an additional group of animals, we performed c-Fos immunohistochemistry to verify the activation of brainstem vagal centers after tVNS. Results: There was no difference in physiological parameters between control and tVNS-treated animals. c-Fos immunohistochemistry showed activation of nucleus tractus solitarius indicating that tVNS was able to activate the same brain stem nuclei activated by direct VNS. The effect of different tVNS techniques on infarct volume was comparable; infarct volume was 28% smaller with atVNS, 30% with ctVNS-1, and 33% with ctVNS-2 as compared with control animals (p<0.05 for all 3 techniques; n=6 per group). The effect of tVNS on tissue outcome was associated with better neurological scores and grip strength measurements (p<0.05 for all 3 techniques). Conclusion: Non-invasive stimulation of the vagus nerve for a brief period of time provides significant protection against ischemic injury in rats. Given its simplicity and feasibility at the setting of acute ischemic stroke, tVNS holds promise for treatment of human stroke.

Cerebrovascular and neuroprotective effects of adamantane derivative.

Objectives. The influence of 5-hydroxyadamantane-2-on was studied on the rats' brain blood flow and on morphological state of brain tissue under the condition of brain ischemia. The interaction of the substance with NMDA receptors was also studied. Methods. Study has been implemented using the methods of local blood flow registration by laser flowmeter, [3H]-MK-801binding, and morphological examination of the brain tissue. We used the models of global transient ischemia of the brain, occlusion of middle cerebral artery, and hypergravity ischemia of the brain. Results. Unlike memantine, antagonist of glutamatergic receptors, the 5-hydroxyadamantane-2-on does not block NMDA receptors but enhances the cerebral blood flow of rats with brain ischemia. This effect is eliminated by bicuculline. Under conditions of permanent occlusion of middle cerebral artery, 5-hydroxyadamantane-2-on has recovered compensatory regeneration in neural cells, axons, and glial cells, and the number of microcirculatory vessels was increased. 5-Hydroxyadamantane-2-on was increasing the survival rate of animals with hypergravity ischemia. Conclusions. 5-Hydroxyadamantane-2-on, an adamantane derivative, which is not NMDA receptors antagonist, demonstrates significant cerebrovascular and neuroprotective activity in conditions of brain ischemia. Presumably, the GABA-ergic system of brain vessels is involved in mechanisms of cerebrovascular and neuroprotective activity of 5-hydroxyadamantane-2-on.

Symptomatic steno-occlusion in patients with acute cerebral infarction: prevalence, distribution, and functional outcome.

Background and PurposeSymptomatic steno-occlusion (SYSO) in acute ischemic stroke has a significant impact on treatment options and prognosis. However, the prevalence, distribution, clinical characteristics, and outcome of SYSO are not well known.MethodsWe retrospectively identified 3,451 patients hospitalized because of ischemic stroke within 24 hours of symptom onset at 9 stroke centers in South Korea. Patients who did not undergo magnetic resonance imaging were excluded. SYSO was defined as stenosis or occlusion of cerebral arteries with relevant ischemic lesions in the corresponding arterial territory. The number, location, and severity of SYSOs and their effects on functional outcome were analyzed.ResultsIn total, 1,929 of 3,057 subjects (63.1%) had SYSO. The most frequently affected vessels were the middle cerebral artery (34.6%), extracranial internal carotid artery (14%), vertebral artery (12.4%), and basilar artery (8.7%). SYSO predicted poor outcome on the modified Rankin Scale 3-6 (odds ratio, 1.77; 95% confidence interval, 1.46-2.15) with adjustments. Involvement of 2 or more vessels was observed in 30.6% of patients with SYSO and independently increased the risk of poor outcome (odds ratio, 2.76; 95% confidence interval, 2.12-3.59). The severity of SYSO was associated with outcome and showed a significant dose-response trend (P<0.001). The effect of SYSO on outcome did not significantly differ by individual arterial location (P for contrast=0.21).ConclusionsApproximately 60% of patients with acute ischemic stroke had SYSO, and the severity and number were inversely correlated with outcome. The results suggest that SYSO could predict stroke outcome.

Drug delivery to the ischemic brain.

Cerebral ischemia occurs when blood flow to the brain is insufficient to meet metabolic demand. This can result from cerebral artery occlusion that interrupts blood flow, limits CNS supply of oxygen and glucose, and causes an infarction/ischemic stroke. Ischemia initiates a cascade of molecular events in neurons and cerebrovascular endothelial cells including energy depletion, dissipation of ion gradients, calcium overload, excitotoxicity, oxidative stress, and accumulation of ions and fluid. Blood-brain barrier (BBB) disruption is associated with cerebral ischemia and leads to vasogenic edema, a primary cause of stroke-associated mortality. To date, only a single drug has received US Food and Drug Administration (FDA) approval for acute ischemic stroke treatment, recombinant tissue plasminogen activator (rt-PA). While rt-PA therapy restores perfusion to ischemic brain, considerable tissue damage occurs when cerebral blood flow is reestablished. Therefore, there is a critical need for novel therapeutic approaches that can "rescue" salvageable brain tissue and/or protect BBB integrity during ischemic stroke. One class of drugs that may enable neural cell rescue following cerebral ischemia/reperfusion injury is the HMG-CoA reductase inhibitors (i.e., statins). Understanding potential CNS drug delivery pathways for statins is critical to their utility in ischemic stroke. Here, we review molecular pathways associated with cerebral ischemia and novel approaches for delivering drugs to treat ischemic disease. Specifically, we discuss utility of endogenous BBB drug uptake transporters such as organic anion transporting polypeptides and nanotechnology-based carriers for optimization of CNS drug delivery. Overall, this chapter highlights state-of-the-art technologies that may improve pharmacotherapy of cerebral ischemia.

Experimental model of ocular ischemic diseases

The review presents the most common methods of modeling of retinal ischemia in vitro (chemical ischemia with iodoacetic acid, incubation of the retinal pigment epithelium cells with oligomycin, deprivation of oxygen and glucose) and in vivo (a model with increased intraocular pressure, cerebral artery occlusion, chronic ligation of the carotid arteries, photocoagulation of the retinal vessels, occlusion of the central retinal artery, endothelin-1 administration). Modeling ischemic injury in rats is the most frequently used method in studies, because the blood supply of their eyes is similar to blood flow in the human eyes. Each method has its own advantages and disadvantages. Application of methods depends on the purpose of the experimental study. Currently model of ocular ischemic disease can be obtained easily by injecting vasoconstrictive drug endothelin-1. It is the most widely used method of high intraocular pressure induced ocular ischemic damage similar to glaucoma, occlusion of central retinal artery or ophthalmic artery in human. The development of experimental models of ocular ischemic diseases and detailed investigation of mechanisms of impairment of microcirculation are useful for improve the efficiency of diagnostic and treatment of ischemic diseases of retina and optic nerve.

Recurrent Transient Ischemic Attacks in a Patient with POEMS Syndrome

A 47-year-old female with a prior history of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome was admitted with transient ischemic attacks complicated by dysarthria and right-sided hemiparesis. A blood survey indicated thrombocytosis and hyperfibrinogenemia while imaging of intracranial vasculature showed occlusion of the bilateral middle cerebral arteries. POEMS syndrome, of which arterial thromboses have been mentioned as a manifestation, is rarely accompanied by transient ischemic attacks. The pathophysiologic mechanism is yet unclear and needs further investigation.

Extract of Antrodia camphorata exerts neuroprotection against embolic stroke in rats without causing the risk of hemorrhagic incidence.

In this study, the neuroprotective effect of an extract of Antrodia camphorata (A. camphorata), a fungus commonly used in Chinese folk medicine for treatment of viral hepatitis and cancer, alone or in combination with aspirin was investigated in a rat embolic stroke model. An ischemic stroke was induced in rats by a selective occlusion of the middle cerebral artery (MCA) with whole blood clots and then orally treated with A. camphorata (0.25 and 0.75 g/kg/day) alone and combined with aspirin (5 mg/kg/day). Sixty days later, the brains were removed, sectioned, and stained with triphenyltetrazolium chloride and analysed by a commercial image processing software program. Brain infarct volume, neurobehavioral score, cerebral blood perfusion, and subarachnoid and intracerebral hemorrhage incidence were perceived. In addition, potential bleeding side effect of the combinative therapy was assessed by measuring hemoglobin (Hb) content during intracerebral hemorrhage and gastric bleeding, prothrombin time (PT), and occlusion time (OT) after oral administration. Posttreatment with high dose A. camphorata significantly reduced infarct volume and improved neurobehavioral score (P < 0.05). Since A. camphorata alone or with aspirin did not alter the Hb level, this treatment is safe and does not cause hemorrhagic incident. Remarkably, the combination of A. camphorata and aspirin did not show a significant effect on the bleeding time, PT and OT increase suggesting that A. camphorata may have the neuroprotective effect without the prolongation of bleeding time or coagulation time. From these observations, we suggest that combinative therapy of A. camphorata and aspirin might offer enhanced neuroprotective efficacies without increasing side effects.

Combination of blood flow asymmetry in the cerebral and cerebellar hemispheres on brain perfusion SPECT predicts 5-year outcome in patients with symptomatic unilateral major cerebral artery occlusion

Background and objective: Misery perfusion increases the risk of stroke recurrence in patients with symptomatic major cerebral artery occlusion. The ratio of brain perfusion contralateral-to-affected asymmetry in the cerebellar hemisphere to brain perfusion affected-to-contralateral asymmetry in the cerebral hemisphere (CblPR/CbrPR) indicates affected-to-contralateral asymmetry of oxygen extraction fraction (OEF) in the cerebral hemisphere. The purpose of the present study was to determine whether the CblPR/CbrPR on brain perfusion single-photon emission computed tomography (SPECT) predicts 5-year outcomes in patients with symptomatic unilateral occlusion of the middle cerebral artery (MCA) or internal carotid artery (ICA).Methods: Brain perfusion was assessed using N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) SPECT in 70 patients. A region of interest (ROI) was manually placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres, and the CblPR/CbrPR was calculated. All patients were prospectively followed for 5 years. The primary end points were stroke recurrence or death.Results: A total of 17 patients exhibited the primary end points, 11 of whom experienced subsequent ipsilateral strokes. Multivariate analysis revealed that only high CblPR/CbrPR was significantly associated with the development of the primary end point or subsequent ipsilateral strokes (95% confidential limits [CIs], 1·130–3·145; P = 0·0114 or 95% CIs, 2·558–5·140; P = 0·0045, respectively). The CblPR/CbrPR provided 65% (11/17) or 91% (10/11) sensitivity and 88% (47/53) or 88% (52/59) specificity in predicting the primary end point or subsequent ipsilateral strokes, respectively.Conclusions: The CblPR/CbrPR on brain perfusion SPECT predicts 5-year outcomes in patients with symptomatic unilateral occlusion of the MCA or ICA.

Prognostic effect of posterior cerebral artery laterality on middle cerebral artery occlusion

To explore the prognostic value of posterior cerebral artery (PCA) laterality in patients with symptomatic middle cerebral artery (MCA) occlusion on standard medical therapy. Forty consecutive patients with first onset isolated atherosclerotic occlusion in M1 segment of MCA received medication from June 2009 to March 2013. All patients underwent magnetic resonance angiography (MRA) for assessment of PCA laterality. Clinical data and modified Rankin Scale (mRS) at 3 months were compared between PCA positive and negative patients. Retrospective analysis was performed on their clinical and imaging data. Among them, 20 patients (50%) showed PCA laterality on MRA and 32 patients (80%) completed a 3-month follow-up. No significant difference existed between PCA laterality positive and negative groups in a favorable outcome of mRS = 0-1 at 3 months (P = 0.433). The presence of PCA laterality showed no prognostic effect on patients with symptomatic MCA occlusion on standard medical therapy.

Mechanical thrombectomy – an alternative treatment option in a patient with acute ischemic stroke and multiple contraindications for systemic thrombolysis: a case report

IntroductionAcute ischemic stroke is a common cause of disability and death in developed countries. Standard therapy for patients who present within 4.5 hours from the onset of symptoms is intravenous thrombolysis if contraindications such as oral anticoagulation, cancer or recent surgery are ruled out. Apart from that, mechanical recanalization is a new treatment option for patients with occlusion of major cerebral arteries as a cause of ischemic stroke.Case presentationIn this case report we describe a 55-year-old Caucasian man with a right hemispheric ischemic syndrome who presented in time but who had multiple contraindications against systemic thrombolysis. He was then treated with mechanical recanalization and recovered. On discharge from the hospital he had only a slight left-sided facial paresis and discrete impairment of motion smoothness in his left hand.ConclusionWe conclude that multimodal imaging should be performed in all patients with an acute onset of neurological symptoms suspicious of ischemic stroke, even if they have contraindications against an intravenous thrombolytic treatment.

Cerebral Infarction on 99mTc-MDP SPECT/CT Imaging

A 70-year-old man with lung cancer underwent whole-body MDP bone scintigraphy to evaluate bone metastases that showed marked tracer uptake in the right side of the head, suggestive of skull metastasis. SPECT/CT imaging was performed for further evaluation. The SPECT images demonstrated increased MDP activity in the region of the brain perfused by the right middle cerebral artery. On CT images, there was a large hypoattenuation area corresponding to elevated MDP accumulation. At the same day, magnetic resonance angiography of the brain revealed occlusion of the right middle cerebral artery.