Attenuation of cerebral vasospasm after subarachnoid hemorrhage in mice overexpressing extracellular superoxide dismutase

Oxidative Stress and Cerebral Vascular Tone: The Role of Reactive Oxygen and Nitrogen Species

The brain's unique characteristics make it exceptionally susceptible to oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) production, reactive nitrogen species (RNS) production, and antioxidant defense mechanisms. This review explores the factors contributing to the brain's vascular tone's vulnerability in the presence of oxidative damage, which can be of clinical interest in critically ill patients or those presenting acute brain injuries. The brain's high metabolic rate and inefficient electron transport chain in mitochondria lead to significant ROS generation. Moreover, non-replicating neuronal cells and low repair capacity increase susceptibility to oxidative insult. ROS can influence cerebral vascular tone and permeability, potentially impacting cerebral autoregulation. Different ROS species, including superoxide and hydrogen peroxide, exhibit vasodilatory or vasoconstrictive effects on cerebral blood vessels. RNS, particularly NO and peroxynitrite, also exert vasoactive effects. This review further investigates the neuroprotective effects of antioxidants, including superoxide dismutase (SOD), vitamin C, vitamin E, and the glutathione redox system. Various studies suggest that these antioxidants could be used as adjunct therapies to protect the cerebral vascular tone under conditions of high oxidative stress. Nevertheless, more extensive research is required to comprehensively grasp the relationship between oxidative stress and cerebrovascular tone, and explore the potential benefits of antioxidants as adjunctive therapies in critical illnesses and acute brain injuries.

Increased NOX2 expression in astrocytes leads to eNOS uncoupling through dihydrofolate reductase in endothelial cells after subarachnoid hemorrhage

Introduction

Endothelial nitric oxide synthase (eNOS) uncoupling plays a significant role in acute vasoconstriction during early brain injury (EBI) after subarachnoid hemorrhage (SAH). Astrocytes in the neurovascular unit extend their foot processes around endothelia. In our study, we tested the hypothesis that increased nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) expression in astrocytes after SAH leads to eNOS uncoupling.

Methods

We utilized laser speckle contrast imaging for monitoring cortical blood flow changes in mice, nitric oxide (NO) kits to measure the level of NO, and a co-culture system to study the effect of astrocytes on endothelial cells. Moreover, the protein levels were assessed by Western blot and immunofluorescence staining. We used CCK-8 to measure the viability of astrocytes and endothelial cells, and we used the H2O2 kit to measure the H2O2 released from astrocytes. We used GSK2795039 as an inhibitor of NOX2, whereas lentivirus and adeno-associated virus were used for dihydrofolate reductase (DHFR) knockdown in vivo and in vitro.

Results

The expression of NOX2 and the release of H2O2 in astrocytes are increased, which was accompanied by a decrease in endothelial DHFR 12 h after SAH. Moreover, the eNOS monomer/dimer ratio increased, leading to a decrease in NO and acute cerebral ischemia. All of the above were significantly alleviated after the administration of GSK2795039. However, after knocking down DHFR both in vivo and in vitro, the protective effect of GSK2795039 was greatly reversed.

Discussion

The increased level of NOX2 in astrocytes contributes to decreased DHFR in endothelial cells, thus aggravating eNOS uncoupling, which is an essential mechanism underlying acute vasoconstriction after SAH.

Cannabidiol’s Multifactorial Mechanisms Has Therapeutic Potential for Aneurysmal Subarachnoid Hemorrhage: a Review

Subarachnoid hemorrhage (SAH) is a major health burden that accounts for approximately 5% of all strokes. The most common cause of a non-traumatic SAH is the rupture of a cerebral aneurysm. The most common symptom associated with SAH is a headache, often described as “the worst headache of my life.” Delayed cerebral ischemia (DCI) is a major factor associated with patient mortality following SAH and is often associated with SAH-induced cerebral vasospasm (CV). Cannabidiol (CBD) is emerging as a potential drug for many therapeutic purposes, including epilepsy, anxiety, and pain relief. We aim to review the potential use of CBD as a treatment option for post-SAH critically ill patients. Through a literature review, we evaluated the known pharmacology and physiological effects of CBD and correlated those with the pathophysiological outcomes associated with cerebral vasospasm following subarachnoid hemorrhage. Although overlap exists, data were formatted into three major categories: anti-inflammatory, vascular, and neuroprotective effects. Based on the amount of information known about the actions of CBD, we hypothesize the anti-inflammatory effects are likely to be the most promising therapeutic mechanism. However, its cardiovascular effects through calcium regulation and its neuroprotective effects against cell death, excitotoxicity, and oxidative stress are all plausible mechanisms by which post-SAH critically ill patients may benefit from both early and late intervention with CBD. More research is needed to better understand if and how CBD might affect neurological and vascular functions in the brain following injury such as subarachnoid hemorrhage.

Neurobehavioral Deficits After Subarachnoid Hemorrhage in Mice: Sensitivity Analysis and Development of a New Composite Score

Background

Because of the failure of numerous clinical trials, various recommendations have been made to improve the usefulness of preclinical studies. Specifically, the STAIR (Stroke Therapy Academic Industry Roundtable) recommendations highlighted functional outcome as a critical measure. Recent reviews of experimental subarachnoid hemorrhage (SAH) studies have brought to light the numerous neurobehavioral scoring systems that are used in preclinical SAH studies. To gain insight into the utility of these scoring systems, as well as to identify a scoring system that best captures the deficits caused by SAH in mice, we designed the current study.

Methods and Results

Adult male C57BL/6J mice were used. One cohort of mice was randomly allocated to either sham or SAH and had functional testing performed on days 1 to 3 post‐SAH using the modified Bederson Score, Katz Score, Garcia Neuroscore, and Parra Neuroscore, as well as 21 individual subtests. A new composite neuroscore was developed using the 8 most diagnostically accurate subtests. To validate the use of the developed composite neuroscore, another cohort of mice was randomly assigned to either the sham or SAH group and neurobehavior was evaluated on days 1 to 3, 5, and 7 after injury. Receiver operating characteristic curves were used to analyze the diagnostic accuracy of each scoring system, as well as the subtests. Of the 4 published scoring systems, the Parra Neuroscore was diagnostically accurate for SAH injury in mice versus the modified Bederson and Katz Scores, but not the Garcia Neuroscore. However, the newly developed composite neuroscore was found to be statistically more diagnostically accurate than even the Parra Neuroscore.

Conclusions

The findings of this study promote use of the newly developed composite neuroscore for experimental SAH studies in mice.

Neurobehavioral testing in subarachnoid hemorrhage: A review of methods and current findings in rodents

The most important aspect of a preclinical study seeking to develop a novel therapy for neurological diseases is whether the therapy produces any clinically relevant functional recovery. For this purpose, neurobehavioral tests are commonly used to evaluate the neuroprotective efficacy of treatments in a wide array of cerebrovascular diseases and neurotrauma. Their use, however, has been limited in experimental subarachnoid hemorrhage studies. After several randomized, double-blinded, controlled clinical trials repeatedly failed to produce a benefit in functional outcome despite some improvement in angiographic vasospasm, more rigorous methods of neurobehavioral testing became critical to provide a more comprehensive evaluation of the functional efficacy of proposed treatments. While several subarachnoid hemorrhage studies have incorporated an array of neurobehavioral assays, a standardized methodology has not been agreed upon. Here, we review neurobehavioral tests for rodents and their potential application to subarachnoid hemorrhage studies. Developing a standardized neurobehavioral testing regimen in rodent studies of subarachnoid hemorrhage would allow for better comparison of results between laboratories and a better prediction of what interventions would produce functional benefits in humans.

A novel fluorescent imaging technique for assessment of cerebral vasospasm after experimental subarachnoid hemorrhage

Various techniques have been developed to study changes in the cerebral vasculature in numerous neuropathological processes including subarachnoid hemorrhage (SAH). One of the most widely employed techniques uses India ink-gelatin casting, which presents numerous challenges due to its high viscosity, rapid solidification, and its impact on immunohistochemical analysis. To overcome these limitations, we developed a novel technique for assessing cerebral vasospasm using cerebrovascular perfusion with ROX, SE (5-Carboxy-X-Rhodamine, Succinimidyl Ester), a fluorescent labeling dye. We found that ROX SE perfusion achieves excellent delineation of the cerebral vasculature, was qualitatively and quantitatively superior to India ink-gelatin casting for the assessment of cerebral vasospasm, permits outstanding immunohistochemical examination of non-vasospasm components of secondary brain injury, and is a more efficient and cost-effective experimental technique. ROX SE perfusion is therefore a novel and highly useful technique for studying cerebrovascular pathology following experimental SAH.

Cerebral vasospasm after transsphenoidal surgery for pituitary adenoma: Case report and review of the literature

INTRODUCTION

Cerebral vasospasm (CVS) is a rare complication of transsphenoidal surgery for pituitary adenomas.

CASE REPORT

The authors describe a symptomatic cerebral ischemia due to an internal carotid, left middle cerebral artery and anterior cerebral artery vasospasm in a patient undergoing transsphenoidal surgery for a pituitary macro adenoma. The patient was successfully treated by an endovascular balloon angioplasty.

CONCLUSION

This issue should be taken into account, even when rare, in every patient who has surgery for a pituitary tumor, particularly when it concerns a large macro adenoma with suprasellar extension. Special precautions must be taken to avoid this rare complication.

Paradoxical Roles of Antioxidant Enzymes: Basic Mechanisms and Health Implications

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate "paradoxical" outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of "antioxidant" nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that "paradoxical" roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways.

Mouse model of subarachnoid hemorrhage: technical note on the filament perforation model

Experiments using genetically engineered mice are regarded as indispensable to gaining a better understanding of the molecular pathophysiology in neuronal injury after subarachnoid hemorrhage (SAH). Therefore, mouse SAH models are becoming increasingly important. The circle of Willis perforation (cWp) model is the most frequently used mouse SAH model. We report and discuss the technical surgical approach, results, and difficulties associated with the cWp model, with reference to the existing literature. Our results largely confirmed previously published results. This model may be the first choice at present, because important pathologies can be reproduced in this model and most findings in the literature are based on it.

Protocol for the induction of subarachnoid hemorrhage in mice by perforation of the Circle of Willis with an endovascular filament

Genetically engineered mice are a valuable tool to investigate the molecular and cellular mechanisms leading to brain damage following subarachnoid hemorrhage (SAH). Therefore, several murine SAH models were developed during the last 15 years. Among those models, the perforation of the Circle of Willis by an endovascular filament or “filament model” turned out to become the most popular one, since it is believed to reproduce some of the most prominent pathophysiological features observed after human SAH. Despite the importance of the endovascular filament model for SAH research, relatively few studies were published using this technique during the past years and a number of laboratories reported problems establishing the technique. This triggered discussions about the standardization, reproducibility, and the reliability of the model. In order to improve this situation, the current paper aims to provide a comprehensive hands-on protocol of the murine endovascular filament model. The protocol proved to result in induction of SAH in mice with high intrapersonal and interpersonal reproducibility and is based on our experience with this technique for more than 10 years. By sharing our experience with this valuable model, we aim to initiate a constantly ongoing discussion process on the improvement of standards and techniques in the field of experimental SAH research.

Curcumin pretreatment induces Nrf2 and an antioxidant response and prevents hemin-induced toxicity in primary cultures of cerebellar granule neurons of rats

Curcumin is a bifunctional antioxidant derived from Curcuma longa. This study identifies curcumin as a neuroprotectant against hemin-induced damage in primary cultures of cerebellar granule neurons (CGNs) of rats. Hemin, the oxidized form of heme, is a highly reactive compound that induces cellular injury. Pretreatment of CGNs with 5–30 μM curcumin effectively increased by 2.3–4.9 fold heme oxygenase-1 (HO-1) expression and by 5.6–14.3-fold glutathione (GSH) levels. Moreover, 15 μM curcumin attenuated by 55% the increase in reactive oxygen species (ROS) production, by 94% the reduction of GSH/glutathione disulfide (GSSG) ratio, and by 49% the cell death induced by hemin. The inhibition of heme oxygenase system or GSH synthesis with tin mesoporphyrin and buthionine sulfoximine, respectively, suppressed the protective effect of curcumin against hemin-induced toxicity. These data strongly suggest that HO-1 and GSH play a major role in the protective effect of curcumin. Furthermore, it was found that 24 h of incubation with curcumin increases by 1.4-, 2.3-, and 5.2-fold the activity of glutathione reductase, glutathione S-transferase and superoxide dismutase, respectively. Additionally, it was found that curcumin was capable of inducing nuclear factor (erythroid-derived 2)-like 2 (Nrf2) translocation into the nucleus. These data suggest that the pretreatment with curcumin induces Nrf2 and an antioxidant response that may play an important role in the protective effect of this antioxidant against hemin-induced neuronal death.

Cerebrospinal fluid superoxide dismutase and serum malondialdehyde levels in patients with aneurysmal subarachnoid hemorrhage: preliminary results

OBJECTIVES

Experimental studies provide evidence that oxidative damage plays a role in the development of vasospasm after aneurysmal subarachnoid hemorrhage (SAH) but data from human studies is still limited. The purpose of this study was to investigate the time course of cerebrospinal fluid (CSF) superoxide dismutase (SOD) and serum malondialdehyde (MDA) changes in patients with aneurysmal SAH.

METHODS

SOD in CSF and MDA in the serum were detected on days 1-3, 5 and 7 after aneurysmal SAH in 21 patients, and the results were compared with 15 patients with hydrocephalus. The results were also compared with those of clinical parameters including the patient's outcome at 6 months.

RESULTS

The mean CSF SOD levels were lower and serum MDA levels were higher than the controls. Patients with a high amount of blood within the cisterns had a trend to decreased SOD while increasing MDA levels.

CONCLUSION

These preliminary results suggest that the levels of antioxidants are decreased after the onset of SAH in the early period, possibly because of increased oxidative stress. Reactive oxygen-mediated oxidative damage may play an important role in inflammation after SAH.

Microthrombosis after experimental subarachnoid hemorrhage: time course and effect of red blood cell-bound thrombin-activated pro-urokinase and clazosentan

Delayed cerebral ischemia (DCI) is a significant cause of morbidity and mortality for patients surviving the rupture of an intracranial aneurysm. Despite an association between vasospasm and DCI, thrombosis and thromboembolism may also contribute to DCI. In this study we investigate the time course of intravascular microclot formation after experimental subarachnoid hemorrhage (SAH) and assess the effects of the following two drugs on microclot burden: mutant thrombin-activated urokinase-type plasminogen activator (scFv/uPA-T), which is bound to red blood cells for use as a thromboprophylactic agent, and clazosentan, an endothelin antagonist. In the first study, adult male C57BL/6 mice were sacrificed at 24 (n=5), 48 (n=6), 72 (n=8), and 96 (n=3) hours after SAH induced by filament perforation of the anterior cerebral artery. Sham animals (n=5) underwent filament insertion without puncture. In the second study, animals received scFv/uPA-T (n=5) 3 hours after hemorrhage, clazosentan (n=5) by bolus and subcutaneous pump after SAH just prior to skin closure, or a combination of scFv/uPA-T and clazosentan (n=4). Control (n=6) and sham (n=5) animals received saline alone. All animals were sacrificed at 48 hours and underwent intra-cardiac perfusion with 4% paraformaldehyde. The brains were then extracted and sliced coronally on a cryostat and processed for immunohistochemistry. An antibody recognizing thrombin-anti-thrombin complexes was used to detect microclots on coronal slices. Microclot burden was calculated for each animal and compared among groups. Following SAH, positive anti-thrombin staining was detected bilaterally in the following brain regions, in order of decreasing frequency: cortex; hippocampus; hypothalamus; basal ganglia. Few microclots were found in the shams. Microclot burden peaked at 48 hours and then decreased gradually. Animals receiving scFv/uPA-T and scFv/uPA-T+clazosentan had a lower microclot burden than controls, whereas animals receiving clazosentan alone had a higher microclot burden (p<0.005). The overall mortality rate in the time course study was 40%; mortality was highest among control animals in the second study. Intravascular microclots form in a delayed fashion after experimental SAH. Microclots may be safely reduced using a novel form of thromboprophylaxis provided by RBC-targeted scFv/uPA-T and represent a potential target for therapeutic intervention in the treatment of DCI.

Effect of N-acetylcysteine on vasospasm in subarachnoid hemorrhage

Vasospasm remains an extremely serious complication that affects patients presenting with subarachnoid hemorrhage (SAH) due to ruptured intracranial aneurysms. The current therapeutic armamentarium is still insufficient in many cases, and the search for new therapies is necessary. In this study, we evaluated the effect of N-acetylcysteine (NAC) on cerebral arterial vasospasm using an experimental model. Twenty-four wistar rats were divided into 4 groups: [1] Control, [2] SAH, [3] SAH+NAC and [4] SAH+Placebo. The experimental model employed double subarachnoid injections of autologous blood. The proposed dose of NAC was 250 mg/kg intraperitoneally per day. We analyzed the inner area of the basilar artery to assess the action of NAC. The experimental model proved to be very adequate, with a mortality rate of 4%. The inner area of the basilar artery in the SAH group showed significant difference to the control group (p=0.009). The use of NAC significantly reduced vasospasm as compared to the untreated group (p=0.048) and established no significant difference to the control group (p=0.098). There was no significant improvement with the administration of placebo (p=0.97). The model of the dual hemorrhage proved to be very useful for vasospasm simulation, with overall low mortality. The administration of NAC significantly reduced vasospasm resulting from SAH, and may represent a new therapeutic alternative.

Effects of intramuscular parecoxib administration on vasospasm in an experimental subarachnoid hemorrhage model

AIM

We examined whether intramuscular parecoxib administration has a preventive or therapeutic effect on vasospasm following experimental subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

Twenty New Zealand White Rabbits were assigned randomly to one of four groups. Animals in Group I were not subjected to SAH (control group). Animals in all other groups were subjected to SAH. Animals in Group II received no treatment after SAH induction (SAH group). Animals in Group III received intramuscular parecoxib (diluted with saline) injection at 6 and at 30 hours after SAH (treatment group). Animals in Group IV received only intramuscular saline injection at 6 and at 30 hours after SAH (vehicle group). Animals were euthanized by perfusion and fixation 48 hours after SAH induction. Basilar artery cross-sectional areas and wall thicknesses were measured. Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

Basilar artery cross-sectional areas in the treatment group were significantly higher than in the SAH or vehicle group (p<.05). Basilar artery wall thickness in the treatment group was significantly smaller than in the SAH or vehicle group (p<.05).

CONCLUSION

Our study revealed that intramuscular administration of parecoxib significantly attenuates vasospasm following experimental SAH.

Simvastatin re-couples dysfunctional endothelial nitric oxide synthase in experimental subarachnoid hemorrhage

Reduced endothelial nitric oxide synthase (eNOS) function has been linked to secondary complications of subarachnoid hemorrhage (SAH). We previously found that there is increased eNOS function after SAH but that it is uncoupled, leading to secondary complications such as vasospasm, microthromboembolism and neuronal apoptosis. Here we test the hypothesis that recoupling eNOS with simvastatin can prevent these complications. SAH was created in mice that were treated with vehicle or simvastatin starting 2 weeks before or 30 minutes after SAH. SAH increased phosphorylated eNOS which was prevented by pre- or post-treatment with simvastatin. Simvastatin pre-treatment also prevented the increase in eNOS monomer formation that was associated with SAH, decreased superoxide anion radical production and increased NO. These changes were associated with decreased vasospasm, microthromboemboli and neuronal injury. The data suggest that simvastatin re-couples eNOS after SAH, leading to decreased secondary complications such as vasospasm, microthromboemboli and neuronal injury.

Astrocyte-derived glutathione attenuates hemin-induced apoptosis in cerebral microvascular cells

Intracerebral hemorrhage (ICH) induces neurovascular injury via poorly defined mechanisms. The aim of this study was to determine whether gliovascular communication may restrict hemorrhagic vascular injury. Hemin, a hemoglobin by-product, concentration- and time-dependently increased apoptotic cell death in mouse bEnd.3 cells and in primary human brain microvascular endothelial cells, at least in part, via a caspase-3 dependent pathway. Cell death was preceded by a NFκB-mediated increase in inflammatory gene expression, including upregulation of inducible nitric oxide synthase (iNOS) expression and activity. Functionally, inhibition of iNOS or the addition of a peroxynitrite decomposition catalyst reduced cell death. Interestingly, co-treatment with astrocyte-conditioned media (ACM) reversed hemin-induced NFκB activation, nitrotyrosine formation, and apoptotic cell death, at least in part, via the release of the endogenous antioxidant, reduced glutathione (GSH). Prior treatment of astrocytes with the GSH-depleting agent, DL-buthionine (S,R)-sulfoximine or direct addition of diethyl maleate, a thiol-depleting agent, to ACM reversed the observed protection. In contrast, neither exogenous GSH nor the GSH precursor, N-acetylcysteine, was protective in bEnd.3 cells. Together, these data support an important role for astrocyte-derived GSH in the maintenance of oxidative balance in the vasculature and suggest therapeutic targeting of the GSH system may reduce neurological injury following ICH.

Characteristics of in vivo animal models of delayed cerebral vasospasm

Animal models provide a basis for clarifying the complex pathogenesis of delayed cerebral vasospasm (DVCS) and for screening of potential therapeutic approaches. The aim of this work was to identify and analyze the most consistent and feasible models and their characteristics for each animal. An online search of the MEDLINE PubMed and EMBASE medical databases (1969 to week 21 of 2007) was performed using the key words "mice", "rat", "rabbit", "canine", and "primate" in combination with "subarachnoid hemorrhage", "model", and "vasospasm". Seven techniques were mainly used to induce experimental subarachnoid hemorrhage in closed and open cranium approaches. Among the great number of experimental SAH methods and associated parameters only a fistful reliable models can be identified and recommended for experimental work in mice, rats, rabbits, dogs and nonhuman primates.

Advances in experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) remains to be a devastating disease with high mortality and morbidity. Two major areas are becoming the focus of the research interest of SAH: these are cerebral vasospasm (CVS) and early brain injury (EBI). This mini review will provide a broad summary of the major advances in experimental SAH during the last 3 years. Treatments interfering with nitric oxide (NO)- or endothelin-pathways continue to show antispasmotic effects in experimental SAH. HIF 1 may play both a detrimental and beneficial role in the setting of SAH, depending on its activation stage. Inflammation and oxidative stress contribute to the pathophysiology of both CVS and EBI. Apoptosis, a major component of EBI after SAH, also underlie the etiology of CVS. Since we recognize now that CVS and EBI are the two major contributors to the significant mortality and morbidity associated with SAH, ongoing research will continue to elucidate the underlying pathophysiological pathways and treatment strategies targeting both CVS and EBI may be more successful and improve outcome of patients with SAH.

Elucidating novel mechanisms of brain injury following subarachnoid hemorrhage: an emerging role for neuroproteomics

Subarachnoid hemorrhage (SAH) is a devastating neurological injury associated with significant patient morbidity and death. Since the first demonstration of cerebral vasospasm nearly 60 years ago, the preponderance of research has focused on strategies to limit arterial narrowing and delayed cerebral ischemia following SAH. However, recent clinical and preclinical data indicate a functional dissociation between cerebral vasospasm and neurological outcome, signaling the need for a paradigm shift in the study of brain injury following SAH. Early brain injury may contribute to poor outcome and early death following SAH. However, elucidation of the complex cellular mechanisms underlying early brain injury remains a major challenge. The advent of modern neuroproteomics has rapidly advanced scientific discovery by allowing proteome-wide screening in an objective, nonbiased manner, providing novel mechanisms of brain physiology and injury. In the context of neurosurgery, proteomic analysis of patient-derived CSF will permit the identification of biomarkers and/or novel drug targets that may not be intuitively linked with any particular disease. In the present report, the authors discuss the utility of neuroproteomics with a focus on the roles for this technology in understanding SAH. The authors also provide data from our laboratory that identifies high-mobility group box protein-1 as a potential biomarker of neurological outcome following SAH in humans.

Neurological and neurobehavioral assessment of experimental subarachnoid hemorrhage

About 50% of humans with aneurysmal subarachnoid hemorrhage (SAH) die and many survivors have neurological and neurobehavioral dysfunction. Animal studies usually focused on cerebral vasospasm and sometimes neuronal injury. The difference in endpoints may contribute to lack of translation of treatments effective in animals to humans. We reviewed prior animal studies of SAH to determine what neurological and neurobehavioral endpoints had been used, whether they differentiated between appropriate controls and animals with SAH, whether treatment effects were reported and whether they correlated with vasospasm. Only a few studies in rats examined learning and memory. It is concluded that more studies are needed to fully characterize neurobehavioral performance in animals with SAH and assess effects of treatment.

Curcumin attenuates vascular inflammation and cerebral vasospasm after subarachnoid hemorrhage in mice

Cerebral vasospasm is a major cause of death and disability after subarachnoid hemorrhage (SAH); however, clinical therapies to limit the development of cerebral vasospasm are lacking. Although the causative factors underlying the development of cerebral vasospasm are poorly understood, oxidative stress contributes to disease progression. In the present study, curcumin (150 or 300 mg/kg) protected against the development of cerebral vasospasm and limited secondary cerebral infarction after SAH in mice. The protective effect of curcumin was associated with a significant attenuation of inflammatory gene expression and lipid peroxidation within the cerebral cortex and the middle cerebral artery. Despite the ability of curcumin to limit the development of cerebral vasospasm and secondary infarction, behavioral outcome was not improved, indicating a dissociation between cerebral vasospasm and neurologic outcome. Together, these data indicate a novel role for curcumin as a possible adjunct therapy after SAH, both to prevent the development of cerebral vasospasm and to reduce oxidative brain injury after secondary infarction.

Hemin-induced necroptosis involves glutathione depletion in mouse astrocytes

Intracerebral hemorrhage (ICH) is a devastating neurological injury associated with significant mortality. Astrocytic inflammation may contribute to the pathogenesis of ICH, although the underlying cellular mechanisms remain unclear. In this study, the hemoglobin oxidation by-product, hemin, concentration dependently induced necroptotic cell death in cortical astrocytes within 5 h of treatment. Hemin-induced cell death was preceded by increased inflammatory gene expression (COX-2, IL-1beta, TNF-alpha, iNOS). Inhibition of the NF-kappaB transcription factor reversed inflammatory gene expression and attenuated cell death after hemin treatment, suggesting a possible role for inflammatory mediators in astrocytic injury. Superoxide production paralleled the increase in iNOS expression, and inhibition of either iNOS (aminoguanidine or iminopiperdine) or superoxide (apocynin) significantly reduced cell death. Similarly, reduced formation of peroxynitrite, the damaging product of nitric oxide and superoxide, significantly reduced hemin injury. Hemin-induced peroxidative injury was associated with a rapid depletion of intracellular glutathione (GSH), culminating in lipid peroxidation and cell death, effects that were reduced by cotreatment with exogenous GSH, N-acetyl-L-cysteine, or the glutathione peroxidase mimetic ebselen. Together, these studies suggest a novel role for GSH depletion in necroptotic astrocyte injury after a hemorrhagic injury and indicate that therapeutic targeting of GSH may exert a beneficial effect after ICH.

Do Statins Improve Outcomes and Reduce the Incidence of Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Background and Purpose— Subarachnoid hemorrhage (SAH) is a relatively rare cause of stroke with a high rate of morbidity and mortality, primarily due to the occurrence of delayed vasospasm. To date, many therapies have been proposed to help prevent vasospasm, but very few have been proven effective. The initiation of statin therapy after SAH may be effective in reducing the incidence of vasospasm; however, the only studies that have examined this effect have been small. This meta-analysis attempted to determine whether statins reduce morbidity and mortality after aneurysmal SAH.

Methods— MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for randomized, controlled trials relating to the use of statins in SAH. Foreign language and abstract articles were included. Two independent reviewers assessed studies for eligibility, data extraction, and quality. Primary outcome was the incidence of radiographically confirmed clinical vasospasm; secondary outcomes were incidence of delayed ischemic deficits and mortality.

Results— The incidence of vasospasm (relative risk [RR]=0.73; 95% CI, 0.54 to 0.99), delayed ischemic deficits (RR=0.38; 95% CI, 0.17 to 0.83), and mortality (RR=0.22; 95% CI, 0.06 to 0.82) were significantly reduced in the statin group. For these outcomes, we calculated a number needed to treat of 6.25, 5, and 6.7, respectively.

Conclusions— Initiation of statin therapy after aneurysmal SAH significantly reduces the incidence of vasospasm, delayed ischemic deficits, and mortality. This is consistent with animal research and retrospective studies and supports the routine use of statins in the care of patients with aneurysmal SAH.

Effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage in rats

The effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage (SAH) was investigated in a rat model. Seven groups of seven rats underwent no SAH, no treatment; SAH only; SAH plus vehicle; SAH plus 3 days intraperitoneal raloxifene treatment; SAH plus 4 days intraperitoneal raloxifene treatment; SAH plus 3 days intrathecal raloxifene treatment; and SAH plus 4 days intrathecal raloxifene treatment. The basilar artery cross-sectional areas were measured at 72 or 96 hours following SAH. The results showed raloxifene decreased SAH-induced cerebral vasospasm in all treatment groups, and suggested no difference between intraperitoneal and intrathecal application, or between 3 days and 4 days of raloxifene treatment. The present study demonstrates that raloxifene is a potential therapeutic agent against cerebral vasospasm after SAH.

Pathophysiology of traumatic brain injury

The knowledge of the pathophysiology after traumatic head injury is necessary for adequate and patient-oriented treatment. As the primary insult, which represents the direct mechanical damage, cannot be therapeutically influenced, target of the treatment is the limitation of the secondary damage (delayed non-mechanical damage). It is influenced by changes in cerebral blood flow (hypo- and hyperperfusion), impairment of cerebrovascular autoregulation, cerebral metabolic dysfunction and inadequate cerebral oxygenation. Furthermore, excitotoxic cell damage and inflammation may lead to apoptotic and necrotic cell death. Understanding the multidimensional cascade of secondary brain injury offers differentiated therapeutic options.

Novel Protein Transduction Method by Using 11R

BACKGROUND AND PURPOSE

A motif of 11 consecutive arginines (11R) is reported to be one of the most effective protein transduction domains for introducing proteins into the cell membrane. We therefore examined the transduction efficiency of 11R in cerebral arteries.

METHODS

Basilar arteries (BAs) obtained from rats were incubated with either 11R-enhanced green fluorescent protein (11R-EGFP) or EGFP without 11R. After incubation, expression of 11R-EGFP or EGFP in BA serial sections was observed by fluorescence microscope. In an additional in vivo experiment, 11R-EGFP or EGFP was injected into the cisterna magna with or without subarachnoid hemorrhage. The 11R-EGFP or EGFP was injected just after the autologous blood injection, and then the expression of 11R-EGFP or EGFP in BA sections was also observed by fluorescence microscope.

RESULTS

The 11R-EGFP signal was much stronger than that of EGFP in all layers of the rat BA, in both in vivo and ex vivo experiments. Moreover, the 11R-EGFP was transduced into the BA immediately (2 hours after the injection). Interestingly, 11R-fused fluorescent protein was transduced especially into the tunica media of the BA.

CONCLUSIONS

The 11R-fused fluorescent protein effectively penetrates into all layers of the rat BA, especially into the tunica media. This is the first study to our knowledge to demonstrate the successful transduction of a protein transduction domain fused protein into the cerebral arteries.

Genetic modification of cerebral arterial wall: implications for prevention and treatment of cerebral vasospasm

Genetic modification of cerebral vessels represents a promising and novel approach for prevention and/or treatment of various cerebral vascular disorders, including cerebral vasospasm. In this review, we focus on the current understanding of the use of gene transfer to the cerebral arteries for prevention and/or treatment of cerebral vasospasm following subarachnoid hemorrhage (SAH). We also discuss the recent developments in vascular therapeutics, involving the autologous use of progenitor cells for repair of damaged vessels, as well as a cell-based gene delivery approach for the prevention and treatment of cerebral vasospasm.

Increased levels of F2-isoprostanes following aneurysmal subarachnoid hemorrhage in humans

Subarachnoid hemorrhage (SAH) resulting from aneurysmal rupture is the major cause of nontraumatic SAH. We hypothesized that oxidative stress could be increased following aneurysmal SAH due to hemoglobin release and ischemia-reperfusion injury and that may further contribute to poor outcome. We collected plasma and cerebrospinal fluid (CSF) samples from 11 non-SAH controls and 15 aneurysmal SAH patients for up to 10 days after surgery and investigated status of oxidative stress in patients. Results showed that mean or peak levels of F(2)-isoprostanes (F(2)-IsoPs), a specific marker of lipid peroxidation, and total nitrate/nitrite, metabolites of nitric oxide and peroxynitrite, in CSF and plasma were significantly higher in SAH patients than in controls. First-day levels were also higher in CSF, but not in plasma, in SAH patients. Moreover, mean and peak levels of CSF F(2)-IsoPs were positively correlated with poor outcome or severity of clinical conditions in patients. Furthermore, levels of retinol, delta-tocopherol, beta+gamma-tocopherol, lutein, beta-carotene, and coenzyme Q(10) in plasma were significantly lower in SAH patients than in controls. Our results indicate that oxidative damage may play important roles in the severity and complications of aneurysmal SAH and suggest that means to suppress lipid peroxidation may be beneficial in improving the outcome of aneurysmal SAH.