Excitatory amino acid antagonists for acute stroke

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from porcine brain, which has potential neuroprotective properties. It is widely used in the treatment of acute ischaemic stroke in Russia, Eastern Europe, China, and other Asian and post-Soviet countries. This is an update of a review first published in 2010 and last updated in 2020.

OBJECTIVES

To assess the benefits and harms of Cerebrolysin or Cerebrolysin-like agents for treating acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Trials Register, CENTRAL, MEDLINE, Embase, Web of Science Core Collection, with Science Citation Index, and LILACS in May 2022 and a number of Russian databases in June 2022. We also searched reference lists, ongoing trials registers, and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing Cerebrolysin or Cerebrolysin-like agents started within 48 hours of stroke onset and continued for any length of time, with placebo or no treatment in people with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Three review authors independently applied the inclusion criteria, assessed trial quality and risk of bias, extracted data, and applied GRADE criteria to the evidence.

MAIN RESULTS

Seven RCTs (1773 participants) met the inclusion criteria of the review. In this update we added one RCT of Cerebrolysin-like agent Cortexin, which contributed 272 participants. We used the same approach for risk of bias assessment that was re-evaluated for the previous update: we added consideration of the public availability of study protocols and reported outcomes to the selective outcome reporting judgement, through identification, examination, and evaluation of study protocols. For the Cerebrolysin studies, we judged the risk of bias for selective outcome reporting to be unclear across all studies; for blinding of participants and personnel to be low in three studies and unclear in the remaining four; and for blinding of outcome assessors to be low in three studies and unclear in four studies. We judged the risk of bias for generation of allocation sequence to be low in one study and unclear in the remaining six studies; for allocation concealment to be low in one study and unclear in six studies; and for incomplete outcome data to be low in three studies and high in the remaining four studies. The manufacturer of Cerebrolysin supported three multicentre studies, either totally, or by providing Cerebrolysin and placebo, randomisation codes, research grants, or statisticians. We judged two studies to be at high risk of other bias and the remaining five studies to be at unclear risk of other bias. We judged the study of Cortexin to be at low risk of bias for incomplete outcome data and at unclear risk of bias for all other domains. All-cause death: Cerebrolysin or Cortexin probably result in little to no difference in all-cause death (risk ratio (RR) 0.96, 95% confidence interval (CI) 0.65 to 1.41; 6 trials, 1689 participants; moderate-certainty evidence). None of the included studies reported on poor functional outcome, defined as death or dependence at the end of the follow-up period, early death (within two weeks of stroke onset), quality of life, or time to restoration of capacity for work. Only one study clearly reported on the cause of death: cerebral infarct (four in the Cerebrolysin and two in the placebo group), heart failure (two in the Cerebrolysin and one in the placebo group), pulmonary embolism (two in the placebo group), and pneumonia (one in the placebo group). Non-death attrition (secondary outcome): Cerebrolysin or similar peptide mixtures may result in little to no difference in non-death attrition, but the evidence is very uncertain, with a considerable level of heterogeneity (RR 0.72, 95% CI 0.38 to 1.39; 6 trials, 1689 participants; very low-certainty evidence). Serious adverse events (SAEs): Cerebrolysin probably results in little to no difference in the total number of people with SAEs (RR 1.16, 95% CI 0.81 to 1.66; 3 trials, 1335 participants; moderate-certainty evidence). This comprised fatal SAEs (RR 0.90, 95% CI 0.59 to 1.38; 3 trials, 1335 participants; moderate-certainty evidence) and an increase in the total number of people with non-fatal SAEs (RR 2.39, 95% CI 1.10 to 5.23; 3 trials, 1335 participants; moderate-certainty evidence). In the subgroup of dosing schedule 30 mL for 10 days (cumulative dose 300 mL), the increase was more prominent (RR 2.87, 95% CI 1.24 to 6.69; 2 trials, 1189 participants). Total number of people with adverse events: Cerebrolysin or similar peptide mixtures may result in little to no difference in the total number of people with adverse events (RR 1.03, 95% CI 0.92 to 1.14; 4 trials, 1607 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Moderate-certainty evidence indicates that Cerebrolysin or Cerebrolysin-like peptide mixtures derived from cattle brain probably have no beneficial effect on preventing all-cause death in acute ischaemic stroke. Moderate-certainty evidence suggests that Cerebrolysin probably has no beneficial effect on the total number of people with serious adverse events. Moderate-certainty evidence also indicates a potential increase in non-fatal serious adverse events with Cerebrolysin use.

Development of a Dihydroquinoline-Pyrazoline GluN2C/2D-Selective Negative Allosteric Modulator of the N-Methyl-d-aspartate Receptor

Subunit-selective inhibition of N-methyl-d-aspartate receptors (NMDARs) is a promising therapeutic strategy for several neurological disorders, including epilepsy, Alzheimer's and Parkinson's disease, depression, and acute brain injury. We previously described the dihydroquinoline-pyrazoline (DQP) analogue 2a (DQP-26) as a potent NMDAR negative allosteric modulator with selectivity for GluN2C/D over GluN2A/B. However, moderate (<100-fold) subunit selectivity, inadequate cell-membrane permeability, and poor brain penetration complicated the use of 2a as an in vivo probe. In an effort to improve selectivity and the pharmacokinetic profile of the series, we performed additional structure-activity relationship studies of the succinate side chain and investigated the use of prodrugs to mask the pendant carboxylic acid. These efforts led to discovery of the analogue (S)-(-)-2i, also referred to as (S)-(-)-DQP-997-74, which exhibits >100- and >300-fold selectivity for GluN2C- and GluN2D-containing NMDARs (IC50 0.069 and 0.035 μM, respectively) compared to GluN2A- and GluN2B-containing receptors (IC50 5.2 and 16 μM, respectively) and has no effects on AMPA, kainate, or GluN1/GluN3 receptors. Compound (S)-(-)-2i is 5-fold more potent than (S)-2a. In addition, compound 2i shows a time-dependent enhancement of inhibitory actions at GluN2C- and GluN2D-containing NMDARs in the presence of the agonist glutamate, which could attenuate hypersynchronous activity driven by high-frequency excitatory synaptic transmission. Consistent with this finding, compound 2i significantly reduced the number of epileptic events in a murine model of tuberous sclerosis complex (TSC)-induced epilepsy that is associated with upregulation of the GluN2C subunit. Thus, 2i represents a robust tool for the GluN2C/D target validation. Esterification of the succinate carboxylate improved brain penetration, suggesting a strategy for therapeutic development of this series for NMDAR-associated neurological conditions.

Targeting NMDA Receptors at the Neurovascular Unit: Past and Future Treatments for Central Nervous System Diseases

The excitatory neurotransmission of the central nervous system (CNS) mainly involves glutamate and its receptors, especially N-methyl-D-Aspartate receptors (NMDARs). These receptors have been extensively described on neurons and, more recently, also on other cell types. Nowadays, the study of their differential expression and function is taking a growing place in preclinical and clinical research. The diversity of NMDAR subtypes and their signaling pathways give rise to pleiotropic functions such as brain development, neuronal plasticity, maturation along with excitotoxicity, blood-brain barrier integrity, and inflammation. NMDARs have thus emerged as key targets for the treatment of neurological disorders. By their large extracellular regions and complex intracellular structures, NMDARs are modulated by a variety of endogenous and pharmacological compounds. Here, we will present an overview of NMDAR functions on neurons and other important cell types involved in the pathophysiology of neurodegenerative, neurovascular, mental, autoimmune, and neurodevelopmental diseases. We will then discuss past and future development of NMDAR targeting drugs, including innovative and promising new approaches.

Cerebroprotection for Acute Ischemic Stroke: Looking Ahead

We search for ischemic stroke treatment knowing we have failed-intensely and often-to translate mechanistic knowledge into treatments that alleviate our patients' functional impairments. Lessons can be derived from our shared failures that may point to new directions and new strategies. First, the principle criticisms of both preclinical and clinical assessments are summarized. Next, previous efforts to develop single-mechanism treatments are reviewed. Finally, new definitions, novel approaches, and different directions are presented. In previous development efforts, the basic science and preclinical assessment of candidate treatments often lacked rigor and sufficiency; the clinical trials may have lacked power, rigor, or rectitude; or most likely both preclinical and clinical investigations were flawed. Single-target agents directed against specific molecular mechanisms proved unsuccessful. The term neuroprotection should be replaced as it has become ambiguous: protection of the entire neurovascular unit may be called cerebral cytoprotection or cerebroprotection. Success in developing cerebroprotection-either as an adjunct to recanalization or as stand-alone treatment-will require new definitions that recognize the importance of differential vulnerability in the neurovascular unit. Recent focus on pleiotropic multi-target agents that act via multiple mechanisms of action to interrupt ischemia at multiple steps may be more fruitful. Examples of pleiotropic treatments include therapeutic hypothermia and 3K3A-APC (activated protein C). Alternatively, the single-target drug NA-1 triggers multiple downstream signaling events. Renewed commitment to scientific rigor is essential, and funding agencies and journals may enforce quality principles of rigor in preclinical science. Appropriate animal models should be selected that are suited to the purpose of the investigation. Before clinical trials, preclinical assessment could include subjects that are aged, of both sexes, and harbor comorbid conditions such as diabetes or hypertension. With these new definitions, novel approaches, and renewed attention to rigor, the prospect for successful cerebroprotective therapy should improve.

Evaluation of the Effectiveness of Post-Stroke Metformin Treatment Using Permanent Middle Cerebral Artery Occlusion in Rats

Stroke is the second leading cause of death worldwide. Treatment options for ischemic stroke are limited, and the development of new therapeutic agents or combined therapies is imperative. Growing evidence suggests that metformin treatment, due to its anti-inflammatory action, exerts a neuroprotective effect against ischemia/reperfusion-induced brain damage. Experimental assessment has typically been performed in models of cerebral transient ischemia followed by long-term reperfusion. The aim of this study was to evaluate the neuroprotective effect of metformin treatment after permanent middle cerebral artery occlusion (pMCAO) without reperfusion in rats. Neurological deficits were assessed using the Longa scale, which offers a graded scale on body movement following pMCAO. Both infarct size and brain oedema area were measured by staining with 2,3,5-triphenyltetrazolium chloride. The number of neurons and total and activated microglia, as well as interleukin 10 (IL-10) production, in brain sections were evaluated by immunohistochemical staining. Our results show that metformin treatment improves the neurological state and reduces infarct size after 120 h of pMCAO. Metformin also prevents neuronal loss in the ischemic cortex but not in the striatum after 48 h of pMCAO. Moreover, post-stroke treatment with metformin significantly decreases the number of total and activated microglia at 48 h. The anti-inflammatory effect of metformin is associated with increased IL-10 production at 48 h after pMCAO. The results of the present study suggest that post-stroke treatment with metformin exerts anti-inflammatory and neuroprotective effects in a pMCAO model.

The role of spreading depolarizations and electrographic seizures in early injury progression of the rat photothrombosis stroke model

Spreading depolarization (SD) and seizures are pathophysiological events associated with cerebral ischemia. Here, we investigated their role for injury progression in the cerebral cortex. Cerebral ischemia was induced in anesthetized male Wistar rats using the photothrombosis (PT) stroke model. SD and spontaneous neuronal activity were recorded in the presence of either urethane or ketamine/xylazine anesthesia. Blood-brain barrier (BBB) permeability, cerebral perfusion, and cellular damage were assessed through a cranial window and repeated intravenous injection of fluorescein sodium salt and propidium iodide until 4 h after PT. Neuronal injury and early lesion volume were quantified by stereological cell counting and manual and automated assessment of ex vivo T2-weighted magnetic resonance imaging. Onset SDs originated at the thrombotic core and invaded neighboring cortex, whereas delayed SDs often showed opposite propagation patterns. Seizure induction by 4-aminopyridine caused no increase in lesion volume or neuronal injury in urethane-anesthetized animals. Ketamine/xylazine anesthesia was associated with a lower number of onset SDs, reduced lesion volume, and neuronal injury despite a longer duration of seizures. BBB permeability increase inversely correlated with the number of SDs at 3 and 4 h after PT. Our results provide further evidence that ketamine may counteract the early progression of ischemic injury.

Biomechanics and hemodynamics of stent-retrievers

In 2015, multiple randomized clinical trials showed an unparalleled treatment benefit of stent-retriever thrombectomy as compared to standard medical therapy for the treatment of a large artery occlusion causing acute ischemic stroke. A short time later, the HERMES collaborators presented the patient-level pooled analysis of five randomized clinical trials, establishing class 1, level of evidence A for stent-retriever thrombectomy, in combination with intravenous thrombolysis when indicated to treat ischemic stroke. In the years following, evidence continues to mount for expanded use of this therapy for a broader category of patients. The enabling technology that changed the tide to support endovascular treatment of acute ischemic stroke is the stent-retriever. This review summarizes the history of intra-arterial treatment of stroke, introduces the biomechanics of embolus extraction with stent-retrievers, describes technical aspects of the intervention, provides a description of hemodynamic implications of stent-retriever embolectomy, and proposes future directions for a more comprehensive, multi-modal endovascular approach for the treatment of acute ischemic stroke.

Neuroprotective and Neurorestorative Effects of Epo and VEGF: Perspectives for New Therapeutic Approaches to Neurological Diseases

BACKGROUND

Erythropoietin (Epo) and vascular endothelial growth factor (VEGF) are two vasoactive molecules with essential trophic effects for brain development. The expression and secretion of both molecules increase in response to neuronal damage and they exert protective and restorative effects, which may also be accompanied by adverse side effects.

OBJECTIVE

We review the most relevant evidence on the neuroprotective and neurorestorative effects of Epo and VEGF in three of the most frequent neurological disorders, namely, stroke, epilepsy and Alzheimer's disease, to develop new therapeutic approaches.

METHODS

Several original scientific manuscripts and reviews that have discussed the evidence in critical way, considering both the beneficial and adverse effects of Epo and VEGF in the selected neurological disorders, were analysed. In addition, throughout this review, we propose several considerations to take into account in the design of therapeutic approaches based on Epo and VEGF signalling.

RESULTS

Although the three selected disorders are triggered by different mechanisms, they evolve through similar processes: excitotoxicity, oxidative stress, neuroinflammation, neuronal death, glial reactivity and vascular remodelling. Epo and VEGF exert neuroprotective and neurorestorative effects by acting on these processes due to their pleiotropism. In general, the evidence shows that both Epo and VEGF reduce neuronal death but that at the vascular level, their effects are contradictory.

CONCLUSION

Because the Epo and VEGF signalling pathways are connected in several ways, we conclude that more experimental studies, primarily studies designed to thoroughly assess the functional interactions between Epo and VEGF in the brain under both physiological and pathophysiological conditions, are needed.

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from porcine brain that has potential neuroprotective properties. It is widely used in the treatment of acute ischaemic stroke in Russia, Eastern Europe, China, and other Asian and post-Soviet countries. This is an update of a review first published in 2010 and last updated in 2017.

OBJECTIVES

To assess the benefits and harms of Cerebrolysin for treating acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, Web of Science Core Collection, with Science Citation Index, LILACS, OpenGrey, and a number of Russian databases in October 2019. We also searched reference lists, ongoing trials registers, and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing Cerebrolysin, started within 48 hours of stroke onset and continued for any length of time, with placebo or no treatment in people with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial quality and risk of bias, extracted data, and applied GRADE criteria to the evidence.

MAIN RESULTS

Seven RCTs (1601 participants) met the inclusion criteria of the review. In this update we re-evaluated risk of bias through identification, examination, and evaluation of study protocols and judged it to be low, unclear, or high across studies: unclear for all domains in one study, and unclear for selective outcome reporting across all studies; low for blinding of participants and personnel in four studies and unclear in the remaining three; low for blinding of outcome assessors in three studies and unclear in four studies. We judged risk of bias to be low in two studies and unclear in the remaining five studies for generation of allocation sequence; low in one study and unclear in six studies for allocation concealment; and low in one study, unclear in one study, and high in the remaining five studies for incomplete outcome data. The manufacturer of Cerebrolysin supported four multicentre studies, either totally, or by providing Cerebrolysin and placebo, randomisation codes, research grants, or statisticians. We judged three studies to be at high risk of other bias and the remaining four studies to be at unclear risk of other bias. All-cause death: we extracted data from six trials (1517 participants). Cerebrolysin probably results in little to no difference in all-cause death: risk ratio (RR) 0.90, 95% confidence interval (CI) 0.61 to 1.32 (6 trials, 1517 participants, moderate-quality evidence). None of the included trials reported on poor functional outcome defined as death or dependence at the end of the follow-up period or early death (within two weeks of stroke onset), or time to restoration of capacity for work and quality of life. Only one trial clearly reported on the cause of death: cerebral infarct (four in the Cerebrolysin and two in the placebo group), heart failure (two in the Cerebrolysin and one in the placebo group), pulmonary embolism (two in the placebo group), and pneumonia (one in the placebo group). Serious adverse events (SAEs): Cerebrolysin probably results in little to no difference in the total number of people with SAEs (RR 1.15, 95% CI 0.81 to 1.65, 4 RCTs, 1435 participants, moderate-quality evidence). This comprised fatal SAEs (RR 0.90, 95% CI 0.59 to 1.38) and an increase in the total number of people with non-fatal SAEs (RR 2.15, 95% CI 1.01 to 4.55, P = 0.047, 4 trials, 1435 participants, moderate-quality evidence). In the subgroup of dosing schedule 30 mL for 10 days (cumulative dose 300 mL), the increase was more prominent: RR 2.86, 95% CI 1.23 to 6.66, P = 0.01 (2 trials, 1189 participants). Total number of people with adverse events: four trials reported on this outcome. Cerebrolysin may result in little to no difference in the total number of people with adverse events: RR 0.97, 95% CI 0.85 to 1.10, P = 0.90, 4 trials, 1435 participants, low-quality evidence. Non-death attrition: evidence from six trials involving 1517 participants suggests that Cerebrolysin results in little to no difference in non-death attrition, with 96 out of 764 Cerebrolysin-treated participants and 117 out of 753 placebo-treated participants being lost to follow-up for reasons other than death (very low-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence indicates that Cerebrolysin probably has little or no beneficial effect on preventing all-cause death in acute ischaemic stroke, or on the total number of people with serious adverse events. Moderate-quality evidence also indicates a potential increase in non-fatal serious adverse events with Cerebrolysin use.

Direct electrophysiological evidence that spreading depolarization-induced spreading depression is the pathophysiological correlate of the migraine aura and a review of the spreading depolarization continuum of acute neuronal mass injury

Spreading depolarization is observed as a large negative shift of the direct current potential, swelling of neuronal somas, and dendritic beading in the brain's gray matter and represents a state of a potentially reversible mass injury. Its hallmark is the abrupt, massive ion translocation between intraneuronal and extracellular compartment that causes water uptake (= cytotoxic edema) and massive glutamate release. Dependent on the tissue's energy status, spreading depolarization can co-occur with different depression or silencing patterns of spontaneous activity. In adequately supplied tissue, spreading depolarization induces spreading depression of activity. In severely ischemic tissue, nonspreading depression of activity precedes spreading depolarization. The depression pattern determines the neurological deficit which is either spreading such as in migraine aura or migraine stroke or nonspreading such as in transient ischemic attack or typical stroke. Although a clinical distinction between spreading and nonspreading focal neurological deficits is useful because they are associated with different probabilities of permanent damage, it is important to note that spreading depolarization, the neuronal injury potential, occurs in all of these conditions. Here, we first review the scientific basis of the continuum of spreading depolarizations. Second, we highlight the transition zone of the continuum from reversibility to irreversibility using clinical cases of aneurysmal subarachnoid hemorrhage and cerebral amyloid angiopathy. These illustrate how modern neuroimaging and neuromonitoring technologies increasingly bridge the gap between basic sciences and clinic. For example, we provide direct electrophysiological evidence for the first time that spreading depolarization-induced spreading depression is the pathophysiological correlate of the migraine aura.

Lasting s-ketamine block of spreading depolarizations in subarachnoid hemorrhage: a retrospective cohort study

Objective

Spreading depolarizations (SD) are characterized by breakdown of transmembrane ion gradients and excitotoxicity. Experimentally, N-methyl-d-aspartate receptor (NMDAR) antagonists block a majority of SDs. In many hospitals, the NMDAR antagonist s-ketamine and the GABA_A agonist midazolam represent the current second-line combination treatment to sedate patients with devastating cerebral injuries. A pressing clinical question is whether this option should become first-line in sedation-requiring individuals in whom SDs are detected, yet the s-ketamine dose necessary to adequately inhibit SDs is unknown. Moreover, use-dependent tolerance could be a problem for SD inhibition in the clinic.

Methods

We performed a retrospective cohort study of 66 patients with aneurysmal subarachnoid hemorrhage (aSAH) from a prospectively collected database. Thirty-three of 66 patients received s-ketamine during electrocorticographic neuromonitoring of SDs in neurointensive care. The decision to give s-ketamine was dependent on the need for stronger sedation, so it was expected that patients receiving s-ketamine would have a worse clinical outcome.

Results

S-ketamine application started 4.2 ± 3.5 days after aSAH. The mean dose was 2.8 ± 1.4 mg/kg body weight (BW)/h and thus higher than the dose recommended for sedation. First, patients were divided according to whether they received s-ketamine at any time or not. No significant difference in SD counts was found between groups (negative binomial model using the SD count per patient as outcome variable, p = 0.288). This most likely resulted from the fact that 368 SDs had already occurred in the s-ketamine group before s-ketamine was given. However, in patients receiving s-ketamine, we found a significant decrease in SD incidence when s-ketamine was started (Poisson model with a random intercept for patient, coefficient − 1.83 (95% confidence intervals − 2.17; − 1.50), p < 0.001; logistic regression model, odds ratio (OR) 0.13 (0.08; 0.19), p < 0.001). Thereafter, data was further divided into low-dose (0.1–2.0 mg/kg BW/h) and high-dose (2.1–7.0 mg/kg/h) segments. High-dose s-ketamine resulted in further significant decrease in SD incidence (Poisson model, − 1.10 (− 1.71; − 0.49), p < 0.001; logistic regression model, OR 0.33 (0.17; 0.63), p < 0.001). There was little evidence of SD tolerance to long-term s-ketamine sedation through 5 days.

Conclusions

These results provide a foundation for a multicenter, neuromonitoring-guided, proof-of-concept trial of ketamine and midazolam as a first-line sedative regime.

Gamma aminobutyric acid (GABA) receptor agonists for acute stroke

BACKGROUND

Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebrovascular disease. However, the sedative effects of GABA receptor agonists have limited their wider application in people with acute stroke, due to the potential risk of stupor. This is an update of a Cochrane Review first published in 2013, and previously updated in 2014 and 2016.

OBJECTIVES

To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (accessed May 2018), the Cochrane Central Register of Controlled Trials (CENTRAL) 2018, Issue 4 (accessed May 2018), MEDLINE (from 1949 to May 2018), Embase (from 1980 to May 2018), CINAHL (from 1982 to May 2018), AMED (from 1985 to May 2018), and 11 Chinese databases (accessed May 2018). In an effort to identify further published, unpublished, and ongoing trials we searched ongoing trial registers, reference lists, and relevant conference proceedings, and contacted authors and pharmaceutical companies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for people with acute stroke (within 12 hours after stroke onset), with the primary outcomes of efficacy and safety.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy, and assessed the risk of bias. We used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We included five trials with 3838 participants (acute ischemic or hemorrhagic stroke patients, 3758 analyzed). Most of the participants recruited had acute ischaemic stroke, with limited data available from participants with other stroke subtypes, including total anterior circulation syndrome (TACS). The methodological quality of the included trials was generally good, with an unclear risk for selection bias only. For death and dependency at three months, pooled results did not find a significant difference for chlormethiazole versus placebo (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.96 to 1.11; four trials; 2909 participants; moderate-quality evidence) and for diazepam versus placebo (RR 0.94, 95% CI 0.82 to 1.07; one trial; 849 participants; moderate-quality evidence). The most frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95; two trials; 2527 participants; moderate-quality evidence) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46; two trials; 2527 participants; moderate-quality evidence).

AUTHORS' CONCLUSIONS

This review provides moderate-quality evidence that fails to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of people with acute stroke. More well-designed RCTs with large samples of participants with total anterior circulation syndrome are required to determine if there are benefits for this subgroup. Somnolence and rhinitis are frequent adverse events related to chlormethiazole.

The need for new approaches in CNS drug discovery: Why drugs have failed, and what can be done to improve outcomes

An important goal of biomedical research is to translate basic research findings into useful medical advances. In the field of neuropharmacology this requires understanding disease mechanisms as well as the effects of drugs and other compounds on neuronal function. Our hope is that this information will result in new or improved treatment for CNS disease. Despite great progress in our understanding of the structure and functions of the CNS, the discovery of new drugs and their clinical development for many CNS disorders has been problematic. As a result, CNS drug discovery and development programs have been subjected to significant cutbacks and eliminations over the last decade. While there has been recent resurgence of interest in CNS targets, these past changes in priority of the pharmaceutical and biotech industries reflect several well-documented realities. CNS drugs in general have higher failure rates than non-CNS drugs, both preclinically and clinically, and in some areas, such as the major neurodegenerative diseases, the clinical failure rate for disease-modifying treatments has been 100%. The development times for CNS drugs are significantly longer for those drugs that are approved, and post-development regulatory review is longer. In this introduction we review some of the reasons for failure, delineating both scientific and technical realities, some unique to the CNS, that have contributed to this. We will focus on major neurodegenerative disorders, which affect millions, attract most of the headlines, and yet have witnessed the fewest successes. We will suggest some changes that, when coupled with the approaches discussed in the rest of this special volume, may improve outcomes in future CNS-targeted drug discovery and development efforts. This article is part of the Special Issue entitled "Beyond small molecules for neurological disorders".

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from pigs' brain tissue, which has potential neuroprotective and neurotrophic properties. It is widely used in the treatment of acute ischaemic stroke in Russia, Eastern Europe, China, and other Asian and post-Soviet countries.

OBJECTIVES

To assess the benefits and risks of cerebrolysin for treating acute ischaemic stroke.

SEARCH METHODS

In May 2016 we searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, Web of Science Core Collection, with Science Citation Index, LILACS, OpenGrey, and a number of Russian Databases. We also searched reference lists, ongoing trials registers and conference proceedings, and contacted the manufacturer of cerebrolysin, EVER Neuro Pharma GmbH (formerly Ebewe Pharma).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing cerebrolysin, started within 48 hours of stroke onset and continued for any time, with placebo or no treatment in people with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied inclusion criteria, assessed trial quality and risk of bias, and extracted data.

MAIN RESULTS

We identified six RCTs (1501 participants) that met the inclusion criteria.We evaluated risk of bias and judged it to be unclear for generation of allocation sequence in four studies and low in two studies; unclear for allocation concealment in five studies and low in one study; high for incomplete outcome data (attrition bias) in five studies and unclear in one study; unclear for blinding; high for selective reporting in four studies and unclear in two; and high for other sources of bias in three studies and unclear in the rest. The manufacturer of cerebrolysin, pharmaceutical company EVER Neuro Pharma, supported three multi-centre studies, either totally, or providing cerebrolysin and placebo, randomisation codes, research grants, or statisticians.None of the included trials reported on poor functional outcome defined as death or dependence at the end of the follow-up period or early death (within two weeks of stroke onset).All-cause death: we extracted data from five trials (1417 participants). There was no difference in the number of deaths: 46/714 in cerebrolysin group versus 47/703 in placebo group; risk ratio (RR) 0.91 95% confidence interval (CI) 0.61 to 1.35 (5 trials, 1417 participants, moderate-quality evidence).Serious adverse events (SAEs): there was no significant difference in the total number of SAEs with cerebrolysin (RR 1.16, 95% CI 0.81 to 1.67). This comprised no difference in fatal SAEs (RR 0.90, 95% CI 0.59 to 1.38) and an increase in the number of people with non-fatal SAEs (20/667 with cerebrolysin and 8/668 with placebo: RR 2.47, 95% CI 1.09 to 5.58, P = 0.03) (3 trials, 1335 participants, moderate-quality evidence).Total number of people with adverse events: three trials reported on this. There was no difference in the total number of people with adverse events: 308/667 in cerebrolysin group versus 307/668 in placebo group; RR 0.97 95% CI 0.86 to 1.09, random-effects model (3 trials, 1335 participants, moderate-quality evidence).

AUTHORS' CONCLUSIONS

The findings of this Cochrane Review do not demonstrate clinical benefits of cerebrolysin for treating acute ischaemic stroke. We found moderate-quality evidence of an increase in non-fatal SAEs with cerebrolysin use but not in total SAEs.

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from pigs' brain tissue, which has potential neuroprotective and neurotrophic properties. It is widely used in the treatment of acute ischaemic stroke in Russia, Eastern Europe, China, and other Asian and post-Soviet countries.

OBJECTIVES

To assess the benefits and risks of cerebrolysin for treating acute ischaemic stroke.

SEARCH METHODS

In May 2016 we searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, Web of Science Core Collection, with Science Citation Index, LILACS, OpenGrey, and a number of Russian Databases. We also searched reference lists, ongoing trials registers and conference proceedings, and contacted the manufacturer of cerebrolysin, EVER Neuro Pharma GmbH (formerly Ebewe Pharma).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing cerebrolysin, started within 48 hours of stroke onset and continued for any time, with placebo or no treatment in people with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied inclusion criteria, assessed trial quality and risk of bias, and extracted data.

MAIN RESULTS

We identified six RCTs (1501 participants) that met the inclusion criteria.We evaluated risk of bias and judged it to be unclear for generation of allocation sequence in four studies and low in two studies; unclear for allocation concealment in five studies and low in one study; high for incomplete outcome data (attrition bias) in five studies and unclear in one study; unclear for blinding; high for selective reporting in four studies and unclear in two; and high for other sources of bias in three studies and unclear in the rest. The manufacturer of cerebrolysin, pharmaceutical company EVER Neuro Pharma, supported three multi-centre studies, either totally, or providing cerebrolysin and placebo, randomisation codes, research grants, or statisticians.None of the included trials reported on poor functional outcome defined as death or dependence at the end of the follow-up period or early death (within two weeks of stroke onset).All-cause death: we extracted data from five trials (1417 participants). There was no difference in the number of deaths: 46/714 in cerebrolysin group versus 47/703 in placebo group; risk ratio (RR) 0.91 95% confidence interval (CI) 0.61 to 1.35 (5 trials, 1417 participants, moderate-quality evidence).Serious adverse events: two trials reported on this outcome, with 90% confidence cerebrolysin increased the risks of serious adverse events by at least one third compared to placebo: 62/589 in cerebrolysin group versus 46/600 in placebo group; RR 1.37 90% CI 1.01 to 1.86 (2 trials, 1189 participants, moderate-quality evidence).Total number of people with adverse events: three trials reported on this. There was no difference in the total number of people with adverse events: 308/667 in cerebrolysin group versus 307/668 in placebo group; RR 0.97 95% CI 0.86 to 1.09, random-effects model (3 trials, 1335 participants, moderate-quality evidence).

AUTHORS' CONCLUSIONS

The findings of this Cochrane Review do not demonstrate clinical benefits of cerebrolysin for treating acute ischaemic stroke. We found moderate-quality evidence suggesting that serious adverse events may be more common with cerebrolysin use in acute ischaemic stroke.

Gamma aminobutyric acid (GABA) receptor agonists for acute stroke

BACKGROUND

Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebrovascular disease. However, the sedative effects of GABA receptor agonists have limited their wider application in people with acute stroke, due to the potential risk of stupor. This is an update of a Cochrane review first published in 2013, and previously updated in 2014.

OBJECTIVES

To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (accessed March 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) 2016, Issue 3, part of the Cochrane Library (accessed March 2016), MEDLINE (from 1949 to March 2016), Embase (from 1980 to March 2016), CINAHL (from 1982 to March 2016), AMED (from 1985 to March 2016), and 11 Chinese databases (accessed March 2016). In an effort to identify further published, unpublished, and ongoing trials we searched ongoing trials registers, reference lists, and relevant conference proceedings, and contacted authors and pharmaceutical companies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for people with acute stroke (within 12 hours after stroke onset), with the primary outcomes of efficacy and safety.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy, and assessed the risk of bias.

MAIN RESULTS

We included five trials with 3838 participants (3758 analyzed). The methodological quality of the included trials was generally good, with an unclear risk for selection bias only. Four trials (N = 2909) measured death and dependency at three months for chlormethiazole versus placebo; pooled results did not find a significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.96 to 1.11). One trial (N = 849) measured this outcome for diazepam versus placebo (RR 0.94, 95% CI 0.82 to 1.07). The most frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95; two trials; N = 2527) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46; two trials; N = 2527).

AUTHORS' CONCLUSIONS

This review provides moderate-quality evidence that fails to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of people with acute stroke. More well-designed RCTs with large samples of participants with total anterior circulation syndrome are required to determine if there are benefits for this subgroup. Somnolence and rhinitis are frequent adverse events related to chlormethiazole.

Blood pressure management in acute stroke

Blood pressure (BP) is elevated in 75% or more of patients with acute stroke and is associated with poor outcomes. Whether to modulate BP in acute stroke has long been debated. With the loss of normal cerebral autoregulation, theoretical concerns are twofold: high BP can lead to cerebral oedema, haematoma expansion or haemorrhagic transformation; and low BP can lead to increased cerebral infarction or perihaematomal ischaemia. Published evidence from multiple large, high-quality, randomised trials is increasing our understanding of this challenging area, such that BP lowering is recommended in acute intracerebral haemorrhage and is safe in ischaemic stroke. Here we review the evidence for BP modulation in acute stroke, discuss the issues raised and look to on-going and future research to identify patient subgroups who are most likely to benefit.

Analysis of Potential Amino Acid Biomarkers in Brain Tissue and the Effect of Galangin on Cerebral Ischemia

Galangin, a potent scavenger of free radicals, has been used as an herbal medicine for various ailments for centuries in Asia. With complex pathophysiology, ischemic stroke is one of the most frequent causes of death and disability worldwide. We have reported that galangin provides direct protection against ischemic injury as a potential neuroprotective agent and has potential therapeutic effects on the changes of serum amino acids in ischemic stroke; however, the mechanism of the changes of amino acids in the ischemic brain tissue has not yet been clarified. In this paper, we explored brain tissue amino acid biomarkers in the acute phase of cerebral ischemia and the effect of galangin on those potential biomarkers. Finally, we identified that glutamic acid, alanine and aspartic acid showed significant changes (p < 0.05 or p < 0.01) in galangin-treated groups compared with vehicle-treated rats and the four enzymes associated with these three AAs’ metabolic pathways; GLUD1, SLC16A10, SLC1A1 and GPT were identified by multiplex interactions with the three amino acids. By metabolite-protein network analysis and molecular docking, six of 28 proteins were identified and might become potential galangin biomarkers for acute ischemic stroke. The data in our study provides thoughts for exploring the mechanism of disease, discovering new targets for drug candidates and elucidating the related regulatory signal network.

Main path and byways: non-vesicular glutamate release by system xc(-) as an important modifier of glutamatergic neurotransmission

System xc(-) is a cystine/glutamate antiporter that exchanges extracellular cystine for intracellular glutamate. Cystine is intracellularly reduced to cysteine, a building block of GSH. As such, system xc(-) can regulate the antioxidant capacity of cells. Moreover, in several brain regions, system xc(-) is the major source of extracellular glutamate. As such this antiporter is able to fulfill key physiological functions in the CNS, while evidence indicates it also plays a role in certain brain pathologies. Since the transcription of xCT, the specific subunit of system xc(-), is enhanced by the presence of reactive oxygen species and inflammatory cytokines, system xc(-) could be involved in toxic extracellular glutamate release in neurological disorders that are associated with increased oxidative stress and neuroinflammation. System xc(-) has also been reported to contribute to the invasiveness of brain tumors and, as a source of extracellular glutamate, could participate in the induction of peritumoral seizures. Two independent reviews (Pharmacol. Rev. 64, 2012, 780; Antioxid. Redox Signal. 18, 2013, 522), approached from a different perspective, have recently been published on the functions of system xc(-) in the CNS. In this review, we highlight novel achievements and insights covering the regulation of system xc(-) as well as its involvement in emotional behavior, cognition, addiction, neurological disorders and glioblastomas, acquired in the past few years. System xc(-) constitutes an important source of extrasynaptic glutamate in the brain. By modulating the tone of extrasynaptic metabotropic or ionotropic glutamate receptors, it affects excitatory neurotransmission, the threshold for overexcitation and excitotoxicity and, as a consequence, behavior. This review describes the current knowledge of how system xc(-) is regulated and involved in physiological as well as pathophysiological brain functioning.

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from pigs' brain tissue, which has potential neuroprotective and neurotrophic properties. It is widely used in the treatment of acute ischaemic stroke in Russia, China, and other Asian and post-Soviet countries.

OBJECTIVES

To assess the benefits and risks of Cerebrolysin for treating acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (October 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (November 2014), MEDLINE (1966 to November 2014), EMBASE (1974 to November 2014), Web of Science Core Collection, with Science Citation Index (1940 to November 2014), LILACS (1982 to December 2014), OpenGrey (1980 to December 2014), and a number of Russian Databases (1998 to December 2014). We also searched reference lists, ongoing trials registers and conference proceedings, and contacted the manufacturer of Cerebrolysin, EVER Neuro Pharma GmbH (formerly Ebewe Pharma).

SELECTION CRITERIA

Randomised controlled trials comparing Cerebrolysin started within 48 hours of stroke onset and continued for at least two weeks with placebo or no treatment in people with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied inclusion criteria, assessed trial quality and risk of bias, and extracted data.

MAIN RESULTS

We included one trial involving 146 participants. We evaluated risk of bias and judged it to be high for generation of allocation sequence, low for allocation concealment, high for incomplete outcome data (attrition bias), unclear for blinding, high for selective reporting and high for other sources of bias. The manufacturer of Cerebrolysin, pharmaceutical company Ebewe, provided Cerebrolysin and the placebo, as well as the randomisation codes. There was no difference in the number of deaths (6/78 in Cerebrolysin group versus 6/68 in placebo group; risk ratio (RR) 0.87, 95% confidence interval (CI) 0.29 to 2.58) or in the total number of adverse events (16.4% versus 10.3%; RR 1.62, 95% CI 0.69 to 3.82) between the treatment and control groups.

AUTHORS' CONCLUSIONS

Routine administration of Cerebrolysin to people with acute ischaemic stroke cannot be supported by the available evidence from RCTs.

A systematic review and meta-analysis of Ginsenoside-Rg1 (G-Rg1) in experimental ischemic stroke

The neuroprotective actions of Ginsenoside-Rg1 (G-Rg1) have been documented for experimental stroke therapy. We used a systematic review and meta-analysis to assess the efficacy of G-Rg1 in experimental ischemic stroke. We identified studies describing the efficacy of G-Rg1 in animal models of focal cerebral ischemia. Primary outcomes were infarct volume and neurological function score (NFS). In all, eleven studies reported significant effects of G-Rg1 for improving the NFS when compared with the control group (P < 0.00001), and four studies reported significant effects of G-Rg1 for reducing infarct volume compared with middle cerebral artery occlusion group (P < 0.00001). Meanwhile, studies reported G-Rg1 was more efficacious than positive control drug nimodipine (0.7 or 1 mg/kg, intraperitoneal) according to NFS (P = 0.009) and infarct volume (p = 0.0002). The results demonstrate a marked efficacy of G-Rg1 in experimental acute ischemic stroke, but raise concerns that our value of effect size might be overestimate due to factors such as study quality and possible publication bias. Even so, the findings suggest G-Rg1 as a candidate neuroprotective drug for human ischemic stroke.

A novel effect of Noscapine on patients with massive ischemic stroke: A pseudo-randomized clinical trial

BACKGROUND

Massive ischemic stroke causes significant mortality and morbidity in stroke patients. The main treatments for massive ischemic stroke are recombinant tissue plasminogen activator (rtPA), craniotomy, and endovascular interventions. Due to destructive effects of bradykinin on the nervous system in ischemic stroke, it seems reasonable that using Noscapine as a Bradykinin antagonist may improve patients' outcome after ischemic stroke. The effect of Noscapine on massive ischemic stroke was shown by the previous pilot study by our group. This pseudo-randomized clinical trial study was designed to assess the result of the pilot study.

METHODS

Patients who had clinical symptoms or computed tomography scan indicative of massive stroke (in full middle cerebral artery territory) were entered to the study. The cases received the drugs according to their turns in emergency ward (pseudo-randomized). The patient group received Noscapine, and the control group received common supportive treatments. The patients and data analyzer were blinded about the data. At the end of the study, to adjust confounding variables we used logistic regression.

RESULTS

After 1-month follow-up, 16 patients in the control group and 11 patients in the case group expired (P = 0.193). Analyzing the data extracted from Rankin scale and Barthel index check lists, revealed no significant differences in the two groups.

CONCLUSION

Despite the absence of significant statistical results in our study, the reduction rate of 16% for mortality rate in Noscapine recipients is clinically remarkable and motivates future studies with larger sample sizes.

Calcium-sensing receptor (CaSR) as a novel target for ischemic neuroprotection

Object

Ischemic brain injury is the leading cause for death and long-term disability in patients who suffer cardiac arrest and embolic stroke. Excitotoxicity and subsequent Ca²⁺-overload lead to ischemic neuron death. We explore a novel mechanism concerning the role of the excitatory extracellular calcium-sensing receptor (CaSR) in the induction of ischemic brain injury.

Method

Mice were exposed to forebrain ischemia and the actions of CaSR were determined after its genes were ablated specifically in hippocampal neurons or its activities were inhibited pharmacologically. Since the CaSR forms a heteromeric complex with the inhibitory type B γ-aminobutyric acid receptor 1 (GABA_BR1), we compared neuronal responses to ischemia in mice deficient in CaSR, GABA_BR1, or both, and in mice injected locally or systemically with a specific CaSR antagonist (or calcilytic) in the presence or absence of a GABA_BR1 agonist (baclofen).

Results

Both global and focal brain ischemia led to CaSR overexpression and GABA_BR1 downregulation in injured neurons. Genetic ablation of Casr genes or blocking CaSR activities by calcilytics rendered robust neuroprotection and preserved learning and memory functions in ischemic mice, partly by restoring GABA_BR1 expression. Concurrent ablation of Gabbr1 gene blocked the neuroprotection caused by the Casr gene knockout. Coinjection of calcilytics with baclofen synergistically enhanced neuroprotection. This combined therapy remained robust when given 6 h after ischemia.

Interpretation

Our study demonstrates a novel receptor interaction, which contributes to ischemic neuron death through CaSR upregulation and GABA_BR1 downregulation, and feasibility of neuroprotection by concurrently targeting these two receptors.

Gamma aminobutyric acid (GABA) receptor agonists for acute stroke

BACKGROUND

Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebral ischemia. However, the sedation effects of GABA receptor agonists have limited their wider application in acute stroke patients due to the potential risk of stupor.

OBJECTIVES

To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (February 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 5), MEDLINE (1949 to June 2014), EMBASE (1980 to June 2014), CINAHL (1982 to June 2014), AMED (1985 to June 2014) and 11 Chinese databases (June 2014). In an effort to identify further published, unpublished and ongoing trials we searched ongoing trials registers, reference lists and relevant conference proceedings, and contacted authors and pharmaceutical companies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for acute stroke patients (within 12 hours after stroke onset), with the outcomes of death or dependency, functional independence and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy and assessed the methodological quality.

MAIN RESULTS

We included five trials with 3838 patients. The methodological quality of the included trials was generally good, with low risk of bias. Four trials measured death and dependency at three months in chlormethiazole versus placebo without significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.95 to 1.11). One trial measured this outcome between diazepam and placebo (RR 0.94, 95% CI 0.82 to 1.07). In the subgroup analysis of total anterior circulation syndrome (TACS), a higher percentage of functional independence was found in the chlormethiazole group (RR 1.33, 95% CI 1.09 to 1.64). The frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46).

AUTHORS' CONCLUSIONS

This review does not provide the evidence to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of patients with acute ischemic or hemorrhagic stroke. Chlormethiazole appeared to be beneficial in improving functional independence in patients with TACS according to the subgroup analysis, but this result must be interpreted with great caution. More well-designed RCTs with large samples of TACS would be required for further confirmation. However, somnolence and rhinitis are frequent adverse events related to chlormethiazole.

Allosteric modulators for the treatment of schizophrenia: targeting glutamatergic networks

Schizophrenia is a highly debilitating mental disorder which afflicts approximately 1% of the global population. Cognitive and negative deficits account for the lifelong disability associated with schizophrenia, whose symptoms are not effectively addressed by current treatments. New medicines are needed to treat these aspects of the disease. Neurodevelopmental, neuropathological, genetic, and behavioral pharmacological data indicate that schizophrenia stems from a dysfunction of glutamate synaptic transmission, particularly in frontal cortical networks. A number of novel pre- and postsynaptic mechanisms affecting glutamatergic synaptic transmission have emerged as viable targets for schizophrenia. While developing orthosteric glutamatergic agents for these targets has proven extremely difficult, targeting allosteric sites of these targets has emerged as a promising alternative. From a medicinal chemistry perspective, allosteric sites provide an opportunity of finding agents with better drug-like properties and greater target specificity. Furthermore, allosteric modulators are better suited to maintaining the highly precise temporal and spatial aspects of glutamatergic synaptic transmission. Herein, we review neuropathological and genomic/genetic evidence underscoring the importance of glutamate synaptic dysfunction in the etiology of schizophrenia and make a case for allosteric targets for therapeutic intervention. We review progress in identifying allosteric modulators of AMPA receptors, NMDA receptors, and metabotropic glutamate receptors, all with the aim of restoring physiological glutamatergic synaptic transmission. Challenges remain given the complexity of schizophrenia and the difficulty in studying cognition in animals and humans. Nonetheless, important compounds have emerged from these efforts and promising preclinical and variable clinical validation has been achieved.

Molecular Dissection of Cyclosporin A's Neuroprotective Effect Reveals Potential Therapeutics for Ischemic Brain Injury

After the onset of brain ischemia, a series of events leads ultimately to the death of neurons. Many molecules can be pharmacologically targeted to protect neurons during these events, which include glutamate release, glutamate receptor activation, excitotoxicity, Ca²⁺ influx into cells, mitochondrial dysfunction, activation of intracellular enzymes, free radical production, nitric oxide production, and inflammation. There have been a number of attempts to develop neuroprotectants for brain ischemia, but many of these attempts have failed. It was reported that cyclosporin A (CsA) dramatically ameliorates neuronal cell damage during ischemia. Some researchers consider ischemic cell death as a unique process that is distinct from both apoptosis and necrosis, and suggested that mitochondrial dysfunction and Δψ collapse are key steps for ischemic cell death. It was also suggested that CsA has a unique neuroprotective effect that is related to mitochondrial dysfunction. Here, I will exhibit examples of neuroprotectants that are now being developed or in clinical trials, and will discuss previous researches about the mechanism underlying the unique CsA action. I will then introduce the results of our cDNA subtraction experiment with or without CsA administration in the rat brain, along with our hypothesis about the mechanism underlying CsA’s effect on transcriptional regulation.

Gamma aminobutyric acid (GABA) receptor agonists for acute stroke

BACKGROUND

Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebral ischemia. However, the sedation effects of GABA receptor agonists have limited their wider application in acute stroke patients due to the potential risk of stupor.

OBJECTIVES

To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (January 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (1949 to March 2012), EMBASE (1980 to March 2012), CINAHL (1982 to March 2012), AMED (1985 to March 2012) and 11 Chinese databases (March 2012). In an effort to identify further published, unpublished and ongoing trials we searched ongoing trials registers, reference lists and relevant conference proceedings, and contacted authors and pharmaceutical companies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for acute stroke patients (within 12 hours after stroke onset), with the outcomes of death or dependency, functional independence and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy and assessed the methodological quality.

MAIN RESULTS

We included five trials with 3838 patients. The methodological quality of the included trials was generally good, with low risk of bias. Four trials measured death and dependency at three months in chlormethiazole versus placebo without significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.95 to 1.11). One trial measured this outcome between diazepam and placebo (RR 0.94, 95% CI 0.82 to 1.07). In the subgroup analysis of total anterior circulation syndrome (TACS), a higher percentage of functional independence was found in the chlormethiazole group (RR 1.33, 95% CI 1.09 to 1.64). The frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46).

AUTHORS' CONCLUSIONS

This review does not provide the evidence to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of patients with acute ischemic or hemorrhagic stroke. Chlormethiazole appeared to be beneficial in improving functional independence in patients with TACS according to the subgroup analysis, but this result must be interpreted with great caution. More well-designed RCTs with large samples of TACS would be required for further confirmation. However, somnolence and rhinitis are frequent adverse events related to chlormethiazole.

Safety and efficacy of NA-1 in patients with iatrogenic stroke after endovascular aneurysm repair (ENACT): a phase 2, randomised, double-blind, placebo-controlled trial

BACKGROUND

Neuroprotection with NA-1 (Tat-NR2B9c), an inhibitor of postsynaptic density-95 protein, has been shown in a primate model of stroke. We assessed whether NA-1 could reduce ischaemic brain damage in human beings.

METHODS

For this double-blind, randomised, controlled study, we enrolled patients aged 18 years or older who had a ruptured or unruptured intracranial aneurysm amenable to endovascular repair from 14 hospitals in Canada and the USA. We used a computer-generated randomisation sequence to allocate patients to receive an intravenous infusion of either NA-1 or saline control at the end of their endovascular procedure (1:1; stratified by site, age, and aneurysm status). Both patients and investigators were masked to treatment allocation. The primary outcome was safety and primary clinical outcomes were the number and volume of new ischaemic strokes defined by MRI at 12-95 h after infusion. We used a modified intention-to-treat (mITT) analysis. This trial is registered with ClinicalTrials.gov, number NCT00728182.

FINDINGS

Between Sept 16, 2008, and March 30, 2011, we randomly allocated 197 patients to treatment-12 individuals did not receive treatment because they were found to be ineligible after randomisation, so the mITT population consisted of 185 individuals, 92 in the NA-1 group and 93 in the placebo group. Two minor adverse events were adjudged to be associated with NA-1; no serious adverse events were attributable to NA-1. We recorded no difference between groups in the volume of lesions by either diffusion-weighted MRI (adjusted p value=0·120) or fluid-attenuated inversion recovery MRI (adjusted p value=0·236). Patients in the NA-1 group sustained fewer ischaemic infarcts than did patients in the placebo group, as gauged by diffusion-weighted MRI (adjusted incidence rate ratio 0·53, 95% CI 0·38-0·74) and fluid-attenuated inversion recovery MRI (0·59, 0·42-0·83).

INTERPRETATION

Our findings suggest that neuroprotection in human ischaemic stroke is possible and that it should be investigated in larger trials.

FUNDING

NoNO Inc and Arbor Vita Corp.

Neuroprotection against traumatic brain injury by a peptide derived from the collapsin response mediator protein 2 (CRMP2)

Neurological disabilities following traumatic brain injury (TBI) may be due to excitotoxic neuronal loss. The excitotoxic loss of neurons following TBI occurs largely due to hyperactivation of N-methyl-d-aspartate receptors (NMDARs), leading to toxic levels of intracellular Ca(2+). The axon guidance and outgrowth protein collapsin response mediator protein 2 (CRMP2) has been linked to NMDAR trafficking and may be involved in neuronal survival following excitotoxicity. Lentivirus-mediated CRMP2 knockdown or treatment with a CRMP2 peptide fused to HIV TAT protein (TAT-CBD3) blocked neuronal death following glutamate exposure probably via blunting toxicity from delayed calcium deregulation. Application of TAT-CBD3 attenuated postsynaptic NMDAR-mediated currents in cortical slices. In exploring modulation of NMDARs by TAT-CBD3, we found that TAT-CBD3 induced NR2B internalization in dendritic spines without altering somal NR2B surface expression. Furthermore, TAT-CBD3 reduced NMDA-mediated Ca(2+) influx and currents in cultured neurons. Systemic administration of TAT-CBD3 following a controlled cortical impact model of TBI decreased hippocampal neuronal death. These findings support TAT-CBD3 as a novel neuroprotective agent that may increase neuronal survival following injury by reducing surface expression of dendritic NR2B receptors.

Investigational therapies for ischemic stroke: neuroprotection and neurorecovery

Stroke is one of the leading causes of death and disability worldwide. Current treatment strategies for ischemic stroke primarily focus on reducing the size of ischemic damage and rescuing dying cells early after occurrence. To date, intravenous recombinant tissue plasminogen activator is the only United States Food and Drug Administration approved therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window. The pathophysiology of stroke is complex and it involves excitotoxicity mechanisms, inflammatory pathways, oxidative damage, ionic imbalances, apoptosis, angiogenesis, neuroprotection, and neurorestoration. Regeneration of the brain after damage is still active days and even weeks after a stroke occurs, which might provide a second window for treatment. A huge number of neuroprotective agents have been designed to interrupt the ischemic cascade, but therapeutic trials of these agents have yet to show consistent benefit, despite successful preceding animal studies. Several agents of great promise are currently in the middle to late stages of the clinical trial setting and may emerge in routine practice in the near future. In this review, we highlight select pharmacologic and cell-based therapies that are currently in the clinical trial stage for stroke.

Neuroprotective effects by nimodipine treatment in the experimental global ischemic rat model : real time estimation of glutamate

OBJECTIVE

Glutamate is a key excitatory neurotransmitter in the brain, and its excessive release plays a key role in the development of neuronal injury. In order to define the effect of nimodipine on glutamate release, we monitored extracellular glutamate release in real-time in a global ischemia rat model with eleven vessel occlusion.

METHODS

TWELVE RATS WERE RANDOMLY DIVIDED INTO TWO GROUPS: the ischemia group and the nimodipine treatment group. The changes of extracellular glutamate level were measured using microdialysis amperometric biosensor, in coincident with cerebral blood flow (CBF) and electroencephalogram. Nimodipine (0.025 µg/100 gm/min) was infused into lateral to the CBF probe, during the ischemic period. Also, we performed Nissl staining method to assess the neuroprotective effect of nimodipine.

RESULTS

During the ischemic period, the mean maximum change in glutamate concentration was 133.22±2.57 µM in the ischemia group and 75.42±4.22 µM (p<0.001) in the group treated with nimodipine. The total amount of glutamate released was significantly different (p<0.001) between groups during the ischemic period. The %cell viability in hippocampus was 47.50±5.64 (p<0.005) in ischemia group, compared with sham group. But, the %cell viability in nimodipine treatment group was 95.46±6.60 in hippocampus (p<0.005).

CONCLUSION

From the real-time monitoring and Nissl staining results, we suggest that the nimodipine treatment is responsible for the protection of the neuronal cell death through the suppression of extracellular glutamate release in the 11-VO global ischemia model of rat.

Nanotechnology applications and approaches for neuroregeneration and drug delivery to the central nervous system

Nanotechnology is the science and engineering concerned with the design, synthesis, and characterization of materials and devices that have a functional organization in at least one dimension on the nanometer (i.e., one billionth of a meter) scale. The potential impact of bottom up self-assembling nanotechnology, custom made molecules that self-assemble or self-organize into higher ordered structures in response to a defined chemical or physical cue, and top down lithographic type technologies where detail is engineered at smaller scales starting from bulk materials, stems from the fact that these nanoengineered materials and devices exhibit emergent mesocale and macroscale chemical and physical properties that are often different than their constituent nanoscale building block molecules or materials. As such, applications of nanotechnology to medicine and biology allow the interaction and integration of cells and tissues with nanoengineered substrates at a molecular (i.e., subcellular) level with a very high degree of functional specificity and control. This review considers applications of nanotechnology aimed at the neuroprotection and functional regeneration of the central nervous system (CNS) following traumatic or degenerative insults, and nanotechnology approaches for delivering drugs and other small molecules across the blood-brain barrier. It also discusses developing platform technologies that may prove to have broad applications to medicine and physiology, including some being developed for rescuing or replacing anatomical and/or functional CNS structures.

Cerebrolysin for acute ischaemic stroke

BACKGROUND

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from pigs' brain tissue which has proposed neuroprotective and neurotrophic properties. It is widely used in the treatment of acute ischaemic stroke in Russia and China.

OBJECTIVES

To assess the benefits and risks of cerebrolysin for treating acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (February 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2009), MEDLINE (1966 to February 2009), EMBASE (1974 to February 2009), LILACS (1982 to February 2009), Science Citation Index (1940 to February 2009), SIGLE Archive (1980 to March 2005), and a number of relevant Russian Databases (1988 to February 2009). We also searched reference lists, ongoing trials registers and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials comparing cerebrolysin with placebo or no treatment in patients with acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Three review authors independently applied the inclusion criteria, assessed trial quality and extracted the data.

MAIN RESULTS

We included one trial involving 146 participants. There was no difference in death (6/78 in the cerebrolysin group versus 6/68 in the placebo group; risk ratio (RR) 0.87, 95% confidence interval (CI) 0.29 to 2.58) or in the total number of adverse events (16.4% versus 10.3%; RR 1.62, 95% CI 0.69 to 3.82) between the treatment and control groups.

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate the effect of cerebrolysin on survival and dependency in people with acute ischaemic stroke. High-quality and large-scale randomised controlled trials may help to gain a better understanding of the potential value of cerebrolysin in acute ischaemic stroke.

Molecular Mechanisms in the Pathogenesis and Treatment of Acute Ischemic Stroke

The management of acute ischemic stroke has not made significant strides since the introduction of recombinant tissue plasminogen activator (r-TPA) two decades ago. The use of other therapies, such as heparin, aspirin, dipyridamole, and/or clopidogrel, have only moderately aided in the treatment of this ischemic disease. Therefore, major medical innovative approaches are critically needed. Because of the side effects associated with r-TPA (specifically bleeding) and its limited 3-h therapeutic window, new studies using current developments encountered in the molecular biology of ischemia are being incorporated into the potential therapy of ischemic stroke. A review of the major advances in the field, including glutamate receptor blockade, magnesium infusion, inflammation blockade, apoptosis inhibition, and other therapies, is introduced with special emphasis on the molecular findings recognized as targets for a better and more effective treatment. As new therapies are being considered, the time of administration is becoming a central point of study for the application of novel therapeutic initiatives.

NMDA receptors in clinical neurology: excitatory times ahead

Since the N-methyl-D-aspartate receptor (NMDAR) subunits were cloned less than two decades ago, a substantial amount of research has been invested into understanding their physiological function in the healthy CNS. Research has also been directed at their pathological roles in various neurological diseases, including disorders resulting from acute excitotoxic insults (eg, ischaemic stroke, traumatic brain injury), diseases due to chronic neurodegeneration (eg, Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis), disorders arising from sensitisation of neurons (eg, epilepsy, neuropathic pain), and neurodevelopmental disorders associated with NMDAR hypofunction (eg, schizophrenia). Selective NMDAR antagonists have not produced positive results in clinical trials. However, there are other NMDAR-targeted therapies used in current practice that are effective for treating some neurological disorders. In this Review, we describe the evidence for the use of these therapies and provide an overview of drugs being investigated in clinical trials. We also discuss new NMDAR-targeted strategies in clinical neurology.

Neuroprotective effects of the β-carboline abecarnil studied in cultured cortical neurons and organotypic retinal cultures

Presently there is no neuroprotective pharmacological treatment of proven clinical safety and efficacy available. The purpose of this study was to investigate whether the beta-carboline, abecarnil (Abe), which has already passed clinical phase III trials in patients with anxiety disorders, is neuroprotective in in vitro models of cerebral ischemia or excitotoxicity. Abe (100 nM) protected cultured cortical neurons when applied 20 min before or 20 min after combined oxygen glucose deprivation (OGD). Furthermore, cultured cortical neurons were protected from NMDA excitotoxicity when Abe (100 nM) was administered 20 min before or concurrent with 100 microM NMDA. In contrast, in adult rat organotypic retinal cultures, Abe failed to protect retinal ganglion cells (RGCs) against glutamate (Glu) excitotoxicity. Thus, although our data demonstrate that Abe is a potential neuroprotectant in cultured neurons, the lack of effect in an organotypical model of Glu toxicity indicates that further study is required before Abe might be considered for human neuroprotection trials.

Estimates of Quality and Reliability With the Physiotherapy Evidence-Based Database Scale to Assess the Methodology of Randomized Controlled Trials of Pharmacological and Nonpharmacological Interventions

Background and Purpose. Systematic reviews and meta-analyses often include an evaluation of the methodological quality of the individual studies that have been included, and are usually conducted by at least 2 individuals. The objective of this study was to assess the methodological quality and reliability of a series of randomized controlled trials (RCTs) of both pharmacological and nonpharmacological interventions by use of the 10-item Physiotherapy Evidence-Based Database (PEDro) Scale. Methods. Two abstractors independently reviewed 81 RCTs assessing a variety of interventions. The Cohen kappa statistic and the intraclass correlation coefficient (ICC) were used to assess agreement between abstractors. Results. The average total PEDro scores were 5.94 (SD=1.43) for all studies combined, 6.88 (SD=1.2) for pharmacological studies, and 5.29 (SD=1.26) for nonpharmacological studies. The median score for pharmacological studies was significantly higher than that for nonpharmacological studies (7 versus 5). Pair-wise kappa scores ranged from a low of .452 for concealed allocation among drug trials to perfect agreement (1.00) for randomization and reporting of results from between-group comparisons. The ICCs associated with the cumulative PEDro score were .91 (95% confidence interval [CI]=.83–.94) for all studies, .89 (95% CI=.78–.95) for pharmacological studies, and .91 (95% CI=.84–.952) for nonpharmacological studies. Discussion and Conclusion. The methodological quality for pharmacological interventions was significantly higher than that for nonpharmacological interventions. There was good agreement between raters at an individual item level and in total PEDro scores. A lack of reporting clarity, poor organization of the report, or the failure to include salient details contributed to less-than-perfect agreement between raters. [Foley NC, Bhogal SK, Teasell RW, et al. Estimates of quality and reliability with the Physiotherapy Evidence-Based Database Scale to assess the methodology of randomized controlled trials of pharmacological and nonpharmacological interventions.Phys Ther. 2006;86:817 – 824.]

Apoptosis: Future Targets for Neuroprotective Strategies

Focal permanent or transient cerebral artery occlusion produces massive cell death in the central core of the infarction, whereas in the peripheral zone (penumbra) nerve cells are subjected to various determining survival and death signals. Cell death in the core of the infarction and in the adult brain is usually considered a passive phenomenon, although events largely depend on the partial or complete disruption of crucial metabolic pathways. Cell death in the penumbra is currently considered an active process largely dependent on the activation of cell death programs leading to apoptosis. Yet cell death in the penumbra includes apoptosis, necrosis, intermediate and other forms of cell death. A rather simplistic view implies poor prospects regarding cell survival in the core of the infarction and therapeutic expectations in the control of cell death and cell survival in the penumbra. However, the capacity for neuroprotection depends on multiple factors, primarily the use of the appropriate agent, at the appropriate time and during the appropriate interval. Understanding the mechanisms commanding cell death and survival area is as important as delimiting the therapeutic time window and the facility of a drug to effectively impact on specific targets. Moreover, the detrimental effects of homeostasis and the activation of multiple pathways with opposing signals following ischemic stroke indicate that better outcome probably does not depend on a single compound but on several drugs acting in combination at the optimal time in a particular patient.

Memantine, an uncompetitive low affinity NMDA open-channel antagonist improves clinical rating scores in a multiple infarct embolic stroke model in rabbits

The blockade of NMDA receptors has been pursued as a strategy to reduce the consequences of acute ischemic stroke (AIS) and NMDA receptors remain a valid therapeutic target to treat AIS. Because the pharmacological and toxicity profile of memantine in Alzheimer's disease patients appears to be good, we determined whether memantine would be effective at improving behavioral performance following embolic strokes in rabbits. For these studies, we used a rabbit multiple infarct ischemia model with a well-defined behavioral endpoint. In this study, memantine dissolved in PBS was given intravenously either as a bolus injection (over 1 min) or infused over 60 min. The P(50) of the control groups measured 24 h after embolization were 1.12 +/- 0.18 mg and 1.08 +/- 0.23 mg for the bolus injected and infused groups, respectively. Bolus injections of memantine at 1 mg/kg and 10 mg/kg were not effective at altering the P(50) value and memantine at a dose of 25 mg/kg was lethal. However, slowly infused memantine (25 mg/kg) significantly increased the P(50) value to 2.31 +/- 0.48 mg and 3.13 +/- 1.13 mg when given 5 and 60 min following embolization, respectively. Memantine administered 180 min following embolization also increased the P(50) value to 2.69 +/- 2.21 mg, but the response was variable. These results suggest that uncompetitive NMDA antagonists, more specifically open channel blockers, which may be alternatives to high affinity NMDA antagonists, may have substantial therapeutic benefit for the treatment of AIS and memantine or new dual activity analogs of memantine should be further pursued as a useful therapy to treat the behavioral deficits associated with multiple-infarct ischemia.

Calcium, mitochondria and oxidative stress in neuronal pathology. Novel aspects of an enduring theme

The interplay among reactive oxygen species (ROS) formation, elevated intracellular calcium concentration and mitochondrial demise is a recurring theme in research focusing on brain pathology, both for acute and chronic neurodegenerative states. However, causality, extent of contribution or the sequence of these events prior to cell death is not yet firmly established. Here we review the role of the alpha-ketoglutarate dehydrogenase complex as a newly identified source of mitochondrial ROS production. Furthermore, based on contemporary reports we examine novel concepts as potential mediators of neuronal injury connecting mitochondria, increased [Ca2+]c and ROS/reactive nitrogen species (RNS) formation; specifically: (a) the possibility that plasmalemmal nonselective cationic channels contribute to the latent [Ca2+]c rise in the context of glutamate-induced delayed calcium deregulation; (b) the likelihood of the involvement of the channels in the phenomenon of 'Ca2+ paradox' that might be implicated in ischemia/reperfusion injury; and (c) how ROS/RNS and mitochondrial status could influence the activity of these channels leading to loss of ionic homeostasis and cell death.

Effect of the Glycine Antagonist Gavestinel on cerebral infarcts in acute stroke patients, a randomized placebo-controlled trial: The GAIN MRI Substudy

BACKGROUND AND PURPOSE

Gavestinel, GV150526, is a selective antagonist at the glycine site of the N-methyl-D-aspartate receptor. The safety and efficacy of GV150526 were studied in two phase III randomized placebo-controlled clinical trials of acute ischemic stroke patients within 6 h from onset [The Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas Trials]. A planned MRI substudy within these trials investigated the effect of gavestinel on infarct volume.

METHODS

Patients enrolled in the GAIN trials at designated MRI substudy sites were eligible if they had a pretreatment acute cortical lesion on diffusion-weighted MRI of at least 1.5 cm diameter or 5 cm(3). Final lesion assessment was performed on T(2)-weighted MRI at month 3. Blinded image analysis was performed centrally. The primary hypothesis was that gavestinel would attenuate lesion growth from baseline relative to placebo.

RESULTS

A total of 106 patients were eligible, 75 (34 gavestinel, 41 placebo) of whom had month 3 scans (primary analysis population). No effects of gavestinel on infarct volume were observed in the primary or other analyses. However, significant associations of lesion volume to clinical severity and outcomes were observed. Ischemic lesion volume decrease was predictive of substantial clinical improvement.

CONCLUSION

Consistent with the clinical outcomes in the GAIN trials, no effects of gavestinel on ischemic infarction was observed. Concordance of results of the clinical outcome trials with those of this infarct volume substudy as well the associations of infarct volume to clinical outcomes further support the potential role of infarct volume as a marker of outcome in dose finding and proof of principle acute stroke trials.

Methodological quality of animal studies on neuroprotection in focal cerebral ischaemia

BACKGROUND

The recurrent failure of apparently promising neuroprotective drugs to improve outcome in trials of patients with acute ischaemic stroke may partially be explained by over-optimistic conclusions about efficacy as a result of methodological shortcomings in preclinical studies. We assessed the methodological quality of animal studies of five different neuroprotective agents that have been tested in 21 clinical trials including a total of more than 12,000 patients with acute ischaemic stroke.

METHODS

We performed a literature search restricted to full publications on the effects of clomethiazole, gavestinel, lubeluzole, selfotel, or tirilazad mesylate on infarct volume or functional outcome in animal models of acute focal cerebral ischaemia. We used a rating scale to assess the methodological quality of the included studies. One point was attributed to each of 10 items. A score of 4 to 6 points was considered "medium" and a score above 7 "high."

RESULTS

A total of 45 articles were included. The median score on the methodological quality index was 3; 18 studies had a medium score and one a high score. Randomised treatment allocation was mentioned in 19 studies (42 %), blinded administration of study medication in 10 (22 %), and blinded outcome assessment in 18 (40 %). The study drug was administered at a median of 10 min (range, -60 to 360 min) after the onset of ischaemia.

CONCLUSION

The evidence for neuroprotective efficacy that formed the basis for initiating the 21 trials was obtained in animal studies with a methodological quality that would, in retrospect, not justify such a decision. More rigorous preclinical study methodology may lead to more reliable and reproducible results.

Pharmacological treatment of ischemic stroke

Current pharmacological strategies for acute ischemic stroke largely mirror those employed in acute coronary syndromes. However, important differences in the effectiveness and versatility of the principal agents have emerged between these 2 clinical settings. In general, the level of success achieved with drugs in acute coronary syndromes has not carried over to the same extent when the same drug types are used in stroke. The principal reason is that reperfusion or anticoagulant therapies in the setting of brain infarction run a significant risk of hemorrhagic transformation that has no direct equivalent in myocardial infarction. Consequently, a significant challenge in acute stroke therapeutics is the ability to select patients for drugs where only a narrow therapeutic margin exists and to identify methods that can minimize hemorrhage risk. Other brain-specific vascular factors also pertain in explaining differences in outcome of drugs generally regarded as having a broad cardiovascular remit. The relatively limited efficacy of antiplatelets in stroke might relate to the composition and heterogeneity of the cerebrovascular lesion, while the poor outcome associated with acute anti-hypertensive use is partly due to loss of cerebrovascular autoregulation. Finally, downstream consequences of arterial occlusion within the brain such as excitotoxicity and plasticity are organ specific and, as such, deserve their own pharmacological approaches. In this review, we describe the general mechanism of each drug class used in ischemic stroke and then report on the clinical experience and application for each.

Drug metabolism and pharmacokinetics, the blood-brain barrier, and central nervous system drug discovery

The worldwide market for therapies for CNS disorders is worth more than 50 billion dollars and is set to grow substantially in the years ahead. This is because: 1) the incidence of many CNS disorders (e.g., Alzheimer's disease, stroke, and Parkinson's disease) increase exponentially after age 65 and 2) the number of people in the world over 65 is about to increase sharply because of a marked rise in fertility after World War II. However, CNS research and development are associated with significant challenges: it takes longer to get a CNS drug to market (12-16 years) compared with a non-CNS drug (10-12 years) and there is a higher attrition rate for CNS drug candidates than for non-CNS drug candidates. This is attributable to a variety of factors, including the complexity of the brain, the liability of CNS drugs to cause CNS side effects, and the requirement of CNS drugs to cross the blood-brain barrier (BBB). This review focuses on BBB penetration, along with pharmacokinetics and drug metabolism, in the process of the discovery and development of safe and effective medicines for CNS disorders.

Nanotechnology approaches for the regeneration and neuroprotection of the central nervous system

Nanotechnology is the science and engineering concerned with the design, synthesis, and characterization of materials and devices that have a functional organization in at least 1 dimension on the nanometer (ie, one-billionth of a meter) scale. The ability to manipulate and control engineered self-assembling (ie, self-organizing) substrates at these scales produces macroscopic physical and/or chemical properties in the bulk material not possessed by the constituent building block molecules alone. This in turn results in a degree of functional integration between the engineered substrates and cellular or physiological systems not previously attainable. Applied nanotechnology aimed at the regeneration and neuroprotection of the central nervous system (CNS) will significantly benefit from basic nanotechnology research conducted in parallel with advances in cell biology, neurophysiology, and neuropathology. Ultimately the goal is to develop novel technologies that directly or indirectly aid in providing neuroprotection and/or a permissive environment and active signaling cues for guided axon growth. In some cases, it is expected that the neurosurgeon will be required to administer these substrates to the patient. As such, in order for nanotechnology applications directed toward neurological disorders to develop to their fullest potential, it will be important for neuroscientists, neurosurgeons, and neurologists to participate and contribute to the scientific process alongside physical science and engineering colleagues. This review will focus on emerging clinical applications aimed at the regeneration and neuroprotection of the injured CNS, and discuss other platform technologies that have a significant potential for being adapted for clinical neuroscience applications.

Sample Size Calculations in Acute Stroke Trials: A Systematic Review of Their Reporting, Characteristics, and Relationship With Outcome

BACKGROUND AND PURPOSE

Only a few randomized controlled trials in acute stroke have shown a treatment-related benefit. Inadequate trial design, especially low sample size, may partly explain this failure. We investigated sample size calculations (SSCs) in a systematic review of acute stroke trials.

METHODS

Full reports of nonconfounded randomized controlled trials that recruited patients within 1 week of stroke onset and were published before the end of 2001 were identified from the Cochrane Library and other bibliographic databases. Information on the SSC and outcome event rates was collected for each trial.

RESULTS

Of 189 identified trial reports, 57 (30%) reported > or =1 components of the SSC, phase II 14/129 (11%) versus phase III 43/60 (72%) (P<0.001), with 32 (56%) giving all the required parameters. Significance (alpha) was mentioned in 54 (96%) reports; 53 used a significance level of alpha=0.05. And 55 (98%) reports gave the power (1-beta) of the study (median [25th and 75th percentile] 0.80 [0.80, 0.90]). The anticipated percentage of control subjects having a primary outcome event was given in 24 (42%) articles: case fatality 21.8% (11.8%, 23.5%, n=4) and combined death or disability/dependency 55.5% (44.5%, 66.3%, n=20); 25 studies used other outcomes and 8 studies gave insufficient information. Four of the 22 trials achieved a control rate within 5% of their prediction. 49 (86%) reports gave the anticipated treatment effect; case fatality: anticipated 9.5% (1.1%, 12.5%, n=6), achieved -0.3% (-4.1%, +2.4%); combined death or disability/dependency: anticipated 13.0% (10.0%, 16.0%, n=25), achieved 1.8% (-0.5%, +5.4%). The median calculated sample size was 600 (198, 995, n=54).

CONCLUSIONS

Too few trial publications report the assumptions underlying their SSC. Most trials were underpowered, ie, power <0.90, used inappropriate assumptions for event rates, and were grossly overoptimistic in their expectation of treatment effect. These deficiencies will together have resulted in trials being far too small and reduced their chance of being able to detect real treatment effects.

Magnesium for acute stroke (Intravenous Magnesium Efficacy in Stroke trial): randomised controlled trial

BACKGROUND

Magnesium is neuroprotective in animal models of stroke, and findings of small clinical pilot trials suggest potential benefit in people. We aimed to test whether intravenous magnesium sulphate, given within 12 h of stroke onset, reduces death or disability at 90 days.

METHODS

2589 patients were randomised within 12h of acute stroke to receive 16 mmol MgSO4 intravenously over 15 min and then 65 mmol over 24 h, or matching placebo. Primary outcome was a global endpoint statistic expressed as the common odds ratio for death or disability at day 90. Secondary outcomes were mortality and death or disability, variously defined as Barthel score less than 95, Barthel score less than 60, and modified Rankin scale more than 1. Predefined subgroup analyses were for the primary endpoint in patients in whom treatment commenced within 6 h versus after 6 h, ischaemic versus non-ischaemic strokes, and cortical stroke syndromes versus non-cortical strokes. Intention-to-treat and efficacy analyses were done.

FINDINGS

The efficacy dataset included 2386 patients. Primary outcome was not improved by magnesium (odds ratio 0.95, 95% CI 0.80-1.13, p=0.59). Mortality was slightly higher in the magnesium-treated group than in the placebo group (hazard ratio 1.18, 95% CI 0.97-1.42, p=0.098). Secondary outcomes did not show any treatment effect. Planned subgroup analyses showed benefit of magnesium in non-cortical strokes (p=0.011) whereas greater benefit had been expected in the cortical group.

INTERPRETATION

Magnesium given within 12 h of acute stroke does not reduce the chances of death or disability significantly, although it may be of benefit in lacunar strokes.