Stroke--a medical emergency

The Next Step in the Treatment of Stroke

Although many patients do not receive reperfusion therapy because of delayed presentation and/or severity and location of infarct, new reperfusion approaches are expanding the window of intervention. Novel application of neuroprotective agents in combination with the latest methods of reperfusion provide a path to improved stroke intervention outcomes. We examine why neuroprotective agents have failed to translate to the clinic and provide suggestions for new approaches. New developments in recanalization therapy in combination with therapeutics evaluated in parallel animal models of disease will allow for novel, intra-arterial deployment of therapeutic agents over a vastly expanded therapeutic time window and with greater likelihood success. Although the field of neuronal, endothelial, and glial protective therapies has seen numerous large trials, the application of therapies in the context of newly developed reperfusion strategies is still in its infancy. Given modern imaging developments, evaluation of the penumbra will likely play a larger role in the evolving management of stroke. Increasingly more patients will be screened with neuroimaging to identify patients with adequate collateral blood supply allowing for delayed rescue of the penumbra. These patients will be ideal candidates for therapies such as reperfusion dependent therapeutic agents that pair optimally with cutting-edge reperfusion techniques.

Morin protects the blood-brain barrier integrity against cerebral ischemia reperfusion through anti-inflammatory actions in rats

This study aimed to investigate the effects of morin on cerebral damage and blood–brain barrier (BBB) integrity in a middle cerebral artery occlusion (MCAO) and reperfusion model. Wistar rats were exposed to MCAO for 2 h, followed by reperfusion. Thirty mg/kg of morin was administered via intraperitoneal injection at the different time points: before ischemia, during ischemia, and at reperfusion. The rats were divided into five groups, including sham, vehicle, and three groups of morin. Twenty-four hours after reperfusion, the rats were tested for neurological deficits, and the brains were harvested to assess brain damage. In addition, brains were harvested 72 h to determine BBB disruption. We found that morin significantly reduced reactive oxygen species production and lipid peroxidation. It also decreased inflammation via reducing the expression of Toll-like receptor 4, nuclear factor kappa-beta. Morin ameliorated cerebral damage and reduced apoptosis through decreasing the cerebral infarct size, including apoptotic cell death. Moreover, morin decreased the BBB damage via reducing Evans blue extravasation, neutrophil infiltration, and increasing tight junction protein expression. Therefore, morin protected against cerebral and BBB damage by attenuating oxidative stress, inflammation, and apoptosis in MCAO and reperfusion models.

Nobiletin alleviates cerebral ischemic-reperfusion injury via MAPK signaling pathway

BACKGROUND

Nobiletin (NOB), isolated from Citrus nobilis, has been reported to inhibit cerebral ischemia/reperfusion (I/R) induced cell apoptosis in the brain. The mechanisms and the protective ability of NOB on cerebral I/R rats are unclear.

METHODS

A middle cerebral artery occlusion (MCAO) rat model was established and treated with different doses of NOB. The neurological deficits, brain water content and brain index were explored after reperfusion, and TTC staining was applied to assess the infarct area. The production of reactive oxygen species (ROS) related enzymes in the ischemic cortex samples from each group was measured. TUNEL staining was performed to evaluate neuronal cell apoptosis in brain tissues. The expression of cell apoptosis related proteins, p-p38 and MAPKAP-2 and the levels of inflammatory factors were examined by western blotting assay and ELISA.

RESULTS

NOB treatment notably improved the neurological deficits, brain water content and brain index in an MCAO model, accompanied by decreased infarct area in the brain tissue. Apoptosis induced by cerebral I/R was also decreased by NOB administration via upregulating Bcl-2 and downregulating Bax and caspase3. The levels of pro-inflammatory mediators TNF-α, IL-6 were reduced and anti-inflammatory cytokine IL-10 was increased by NOB treatment in MCAO rats. Further, we found that the expression of p-p38 and MAPKAP-2 was reduced by NOB treatment in MCAO rats.

CONCLUSION

The present results suggest that NOB serves a protective role in I/R-induced cerebral-neuron injury. The mechanisms underlying these effects may be associated with the MAPK signaling pathway.

Acute Ischaemic Stroke: Management, Recent Advances and Controversies

Acute ischaemic stroke is a major cause of death and disability. It may become an enormous burden to the patients themselves, their families as well as the health care systems. Patients at risk of airway, breathing and circulatory compromise should receive prompt resuscitation. Vital parameters and neurological status should be closely monitored. Attentions to blood pressure, temperature and sugar profile are important. The significance of early and correct diagnosis and subsequent treatment cannot be over-emphasised. There have been tremendous recent advances in different treatment modalities in acute stroke management. Various recanalisation modalities include intravenous and/or intra-arterial thrombolysis, acute defibrinogenation, anti-platelet treatment and anticoagulation. Carotid endarterectomy and endovascular strategies are recommended in selected patients. Advanced neuro-imaging techniques and neuroprotectants are being evaluated. Multidisciplinary stroke teams have been shown to improve patient survival and functional outcome. Pre-defined algorithms and protocols should be in place to expedite smooth and effective delivery of stroke service. Future directions should be aimed at exploring safer recanalisation modalities and extending the limit of the current 3-hour treatment window for thrombolysis.

Dihydrocapsaicin Attenuates Blood Brain Barrier and Cerebral Damage in Focal Cerebral Ischemia/Reperfusion via Oxidative Stress and Inflammatory

This study investigated the effect of dihydrocapsaicin (DHC) on cerebral and blood brain barrier (BBB) damage in cerebral ischemia and reperfusion (I/R) models. The models were induced by middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion. The rats were divided into five groups: sham, or control group; vehicle group; and 2.5 mg/kg, 5 mg/kg, and 10 mg/kg BW DHC-treated I/R groups. After 24 h of reperfusion, we found that DHC significantly reduced the area of infarction, morphology changes in the neuronal cells including apoptotic cell death, and also decreased the BBB damage via reducing Evan Blue leakage, water content, and ultrastructure changes, in addition to increasing the tight junction (TJ) protein expression. DHC also activated nuclear-related factor-2 (Nrf2) which involves antioxidant enzymes like superoxide dismutase (SOD) and glutathione peroxidase (GPx), and significantly decreased oxidative stress and inflammation via down-regulated reactive oxygen species (ROS), NADPH oxidase (NOX2, NOX4), nuclear factor kappa-beta (NF-ĸB), and nitric oxide (NO), including matrix metalloproteinases-9 (MMP-9) levels. DHC protected the cerebral and the BBB from I/R injury via attenuation of oxidative stress and inflammation. Therefore, this study offers to aid future development for protection against cerebral I/R injury in humans.

Management of Ischemic Stroke in the Next Decade: Stroke Centers of Excellence

Stroke has been increasingly recognized as an important and expensive medical and societal problem during the past 10 years. Currently, organized stroke care is delivered to the American population in only a few cities and hospitals that provide an efficient system for rapid transportation, diagnosis, treatment, and rehabilitation. The Brain Attack Coalition (BAC) has recently proposed the concepts of stroke centers of excellence (akin to trauma level I centers), primary stroke centers, and comprehensive stroke center. The U.S. government, with the Paul Coverdell National Acute Stroke Registry and the Stroke Treatment and Ongoing Prevention Act of 2003, further supports these concepts. Herein, a discussion of the influence that the BAC, the Paul Coverdell National Acute Stroke Registry, and the Stroke Treatment and Ongoing Prevention Acts of 2001 and 2003 will have on the future of stroke therapy in this country during the next 10 years is presented. Also discussed are the elements that are crucial to organized stroke care and the formation of stroke centers of excellence. These include triage and diagnosis in the field, transportation, triage and imaging in the emergency department, prompt transfer to a dedicated stroke unit with focused care, rehabilitation, manpower, prevention and research, reimbursement issues, and politics. The importance of multidisciplinary collaboration on the professional and societal levels and, finally, government- and private sector-sponsored research are also presented.

Current management of acute ischemic stroke. Part 2: Antithrombotics, neuroprotectives, and stroke units

OBJECTIVE

To help family physicians who care for patients with acute stroke or who are involved in planning service delivery or resource allocation to understand recent developments in acute stroke care.

QUALITY OF EVIDENCE

A MEDLINE search indicated that most data were derived from well designed, randomized, double-blind, placebo-controlled trials, including all the largest international studies and large systematic reviews.

MAIN MESSAGE

Routine anticoagulation is not recommended except for circumstances such as cardioembolic stroke or deep vein thrombosis prophylaxis. Antiplatelet therapy with low-dose acetylsalicylic acid (or another antiplatelet agent if ASA is contraindicated) should be initiated within 48 hours of stroke onset, although benefit is modest. Dedicated care for stroke patients reduces morbidity and mortality and can be cost effective. Recent research into defibrinogenating and neuroprotective agents suggests some benefit, although none are currently licensed for use. Combination therapy might be the answer.

CONCLUSION

Management of acute stroke is an emerging discipline; many potential therapies are still experimental.

Current management of acute ischemic stroke. Part 1: Thrombolytics and the 3-hour window

OBJECTIVE

To help family physicians who care for patients with acute stroke or who are involved in planning service delivery or resource allocation to understand recent developments in acute stroke care.

QUALITY OF EVIDENCE

A MEDLINE search indicated that most data were derived from well designed, randomized, double-blind, placebo-controlled trials, including all the largest international studies and large systematic reviews.

MAIN MESSAGE

Treatment of acute stroke with tissue plasminogen activator seems beneficial for certain patients with certain kinds of stroke. Because thrombolytic therapy is not without risk and requires substantial resources, it should be administered only by physicians trained in its use and in centres with the necessary experience and resources. Because time is important, an organized and efficient system of stroke care with collaboration between hospital and prehospital care providers and help from ordinary citizens is essential.

CONCLUSION

Management of acute stroke is an emerging discipline; many potential therapies are still experimental.

Nitric oxide is involved in anoxic preconditioning neuroprotection in rat hippocampal slices

Sublethal anoxia/ischemia protects against subsequent damaging insults in intact brain or hippocampal slices. To help further understand mechanisms underlying anoxic/ischemic preconditioning, we tested three hypotheses which were that: (a) anoxic preconditioning (APC) improves electrical recovery in rat hippocampal slices; (b) anoxic preconditioning requires nitric oxide (NO); and (c) anoxic preconditioning blocks mitochondrial dysfunction that occurs following re-oxygenation after anoxia. Control hippocampal slices underwent a single 'test' anoxic insult. Experimental slices were preconditioned by 3 short anoxic insults prior to the 'test' insult. Evoked potentials (EPs), and NADH redox status were recorded prior to, during and after preconditioning and/or 'test' anoxic insults. To examine the role of NO, studies sought to determine whether APC could be produced by the NO donor, DEA/NO, and whether APC could be inhibited by NO synthase (NOS) inhibitor (7-nitroindazole). EP amplitudes recovered significantly better after reoxygenation in preconditioned slices and after NO-emulated preconditioning (90.0+/-17.7% and 90.0+/-21.3%, respectively, n=9, ** p<0.01, vs. 17.0+/-7.9%, n=9, in control slices). Inhibition of NOS blocked APC protection (6.8+/-6.8%, n=9). The intensity of NADH hyperoxidation was not significantly different among groups following 'test' anoxia. These data confirm that preconditioning by anoxia improves electrical recovery after anoxia in hippocampal slices. Evidence supports that NO from constitutive hippocampal NOS may be involved in the neuroprotection afforded by preconditioning by a mechanism that does not change the apparent mitochondrial hyperoxidation after anoxia.