The significance of morphological changes in cerebral arteries after subarachnoid hemorrhage

Nimodipine vs. Milrinone – Equal or Complementary Use? A Retrospective Analysis

Background

Cerebral vasospasm (CVS) continues to account for high morbidity and mortality in patients surviving the initial aneurysmal subarachnoid hemorrhage (SAH). Nimodipine is the only drug known to reduce delayed cerebral ischemia (DCI), but it is believed not to affect large vessel CVS. Milrinone has emerged as a promising option. Our retrospective study focused on the effectiveness of the intra-arterial application of both drugs in monotherapy and combined therapy.

Methods

We searched for patients with aneurysmal SAH, angiographically confirmed CVS, and at least one intra-arterial pharmacological angioplasty. Ten defined vessel sections on angiograms were assessed before and after vasodilator infusion. The improvement in vessel diameters was compared to the frequency of DCI-related cerebral infarction before hospital discharge and functional outcome reported as the modified Rankin Scale (mRS) score after 6 months.

Results

Between 2014 and 2021, 132 intra-arterial interventions (144 vascular territories, 12 bilaterally) in 30 patients were analyzed for this study. The vasodilating effect of nimodipine was superior to milrinone in all intradural segments. There was no significant intergroup difference concerning outcome in mRS (p = 0.217). Only nimodipine or the combined approach could prevent DCI-related infarction (both 57.1%), not milrinone alone (87.5%). Both drugs induced a doubled vasopressor demand due to blood pressure decrease, but milrinone alone induced tachycardia.

Conclusions

The monotherapy with intra-arterial nimodipine was superior to milrinone. Nimodipine and milrinone may be used complementary in an escalation scheme with the administration of nimodipine first, complemented by milrinone in cases of severe CVS. Milrinone monotherapy is not recommended.

Relevance of Porcine Stroke Models to Bridge the Gap from Pre-Clinical Findings to Clinical Implementation

In the search of animal stroke models providing translational advantages for biomedical research, pigs are large mammals with interesting brain characteristics and wide social acceptance. Compared to rodents, pigs have human-like highly gyrencephalic brains. In addition, increasingly through phylogeny, animals have more sophisticated white matter connectivity; thus, ratios of white-to-gray matter in humans and pigs are higher than in rodents. Swine models provide the opportunity to study the effect of stroke with emphasis on white matter damage and neuroanatomical changes in connectivity, and their pathophysiological correlate. In addition, the subarachnoid space surrounding the swine brain resembles that of humans. This allows the accumulation of blood and clots in subarachnoid hemorrhage models mimicking the clinical condition. The clot accumulation has been reported to mediate pathological mechanisms known to contribute to infarct progression and final damage in stroke patients. Importantly, swine allows trustworthy tracking of brain damage evolution using the same non-invasive multimodal imaging sequences used in the clinical practice. Moreover, several models of comorbidities and pathologies usually found in stroke patients have recently been established in swine. We review here ischemic and hemorrhagic stroke models reported so far in pigs. The advantages and limitations of each model are also discussed.

Blood-Related Toxicity after Traumatic Brain Injury: Potential Targets for Neuroprotection

Emergency visits, hospitalizations, and deaths due to traumatic brain injury (TBI) have increased significantly over the past few decades. While the primary early brain trauma is highly deleterious to the brain, the secondary injury post-TBI is postulated to significantly impact mortality. The presence of blood, particularly hemoglobin, and its breakdown products and key binding proteins and receptors modulating their clearance may contribute significantly to toxicity. Heme, hemin, and iron, for example, cause membrane lipid peroxidation, generate reactive oxygen species, and sensitize cells to noxious stimuli resulting in edema, cell death, and increased morbidity and mortality. A wide range of other mechanisms such as the immune system play pivotal roles in mediating secondary injury. Effective scavenging of all of these pro-oxidant and pro-inflammatory metabolites as well as controlling maladaptive immune responses is essential for limiting toxicity and secondary injury. Hemoglobin metabolism is mediated by key molecules such as haptoglobin, heme oxygenase, hemopexin, and ferritin. Genetic variability and dysfunction affecting these pathways (e.g., haptoglobin and heme oxygenase expression) have been implicated in the difference in susceptibility of individual patients to toxicity and may be target pathways for potential therapeutic interventions in TBI. Ongoing collaborative efforts are required to decipher the complexities of blood-related toxicity in TBI with an overarching goal of providing effective treatment options to all patients with TBI.

A new non-craniotomy model of subarachnoid hemorrhage in the pig: a pilot study

Subarachnoid hemorrhage (SAH) from rupture of an intracranial arterial aneurysm is a devastating disease affecting young people, with serious lifelong disability or death as a frequent outcome. Large animal models that exhibit all the cardinal clinical features of human SAH are highly warranted. In this pilot study we aimed to develop a non-craniotomy model of SAH in pigs suitable for acute intervention studies. Six Norwegian Landrace pigs received advanced invasive hemodynamic and intracranial pressure (ICP) monitoring. The subarachnoid space, confirmed by a clear cerebrospinal fluid (CSF) tap, was reached by advancing a needle below the ocular bulb through the superior orbital fissure and into the interpeduncular cistern. SAH was induced by injecting 15 mL of autologous arterial blood into the subarachnoid space. Macro- and microanatomical investigations of the pig brain showed a typical blood distribution consistent with human aneurysmal SAH (aSAH) autopsy data. Immediately after SAH induction ICP sharply increased with a concomitant reduction in cerebral perfusion pressure (CPP). ICP returned to near normal values after 30 min, but increased subsequently during the experimental period. Signs of brain edema were confirmed by light microscopy post-mortem. None of the animals died during the experimental period. This new transorbital injection model of SAH in the pig mimics human aSAH and may be suitable for acute intervention studies. However, the model is technically challenging and needs further validation.

Mechanism of Cerebral Vasospasm Following Subarachnoid Hemorrhage in Monkeys

This paper reviews our recent studies on the mechanism of cerebral vasospasm following subarachnoid hemorrhage (SAH) in monkeys. Middle cerebral artery (MCA) vasospasm was maximal at 7 days, resolving by 14 days, and absent at 28 days after SAH. Arterial fibrosis was not detected during vasospasm, although there was intimal hyperplasia with fibrosis 28 days after SAH. On scanning electron microscopy, smooth muscle cells from vasospastic arteries had corrugated cell membranes and appeared similar to cells contracted pharmacologically, suggesting that vasospastic smooth muscle is contracted. Morphometric analysis of arteries obtained 7 days after SAH showed no significant increases in arterial wall area of vasospastic arteries compared with normal MCAs. The results suggest vasospasm in monkeys is not due to hypertrophy, hyperplasia, or fibrosis in the arterial wall. Vasospasm may be mainly vascular smooth muscle contraction, which damages the arterial wall, leading to secondary structural changes in the arterial wall which occur after angiographic vasospasm.

Mesenchymal stem cells improved the ultrastructural morphology of cerebral tissues after subarachnoid hemorrhage in rats

Subarachnoid hemorrhage (SAH) causes widespread disruption in the cerebral architecture.The process of SAH is complicated and many people lose their lives or become disabled after injury. Mesenchymal stem cells (MSCs) are considered as good candidate for repair of cerebral damage. The aim was to assess the ultrastructural changes in the rat cerebral tissue after intravenous transplantation of MSCs. Female Wistar rats (8 per group) weighing 275~300 g were assigned to control (SAH+PBS) and experimental groups (SAH+MSCs).The samples from middle cerebral arterial wall and parietal cerebral tissue were prepared for transmission electron microscopy (TEM) according to standard protocol. Fine architectures of the vessel wall, including the contraction of the inner layer, smooth muscle layer,as well as neural cells were observed after SAH. Cerebral arterial wall and cortex, including neuronal and glial cells were injured post SAH. But, administration of MSCs improved the structural integrity of cerebral tissues. Changes were much more balanced with their relative improvement in some areas. The role of MSCs for repairing the injured cerebral tissues post experimental SAH was approved by electron microscopy.

Smooth muscle phenotype switching in blast traumatic brain injury-induced cerebral vasospasm

Due to increased survival rates among soldiers exposed to explosive blasts, blast-induced traumatic brain injury (bTBI) has become much more prevalent in recent years. Cerebral vasospasm (CVS) is a common manifestation of brain injury whose incidence is significantly increased in bTBI. CVS is characterized by initial vascular smooth muscle cell (VSMC) hypercontractility, followed by prolonged vessel remodeling and lumen occlusion, and is traditionally associated with subarachnoid hemorrhage (SAH), but recent results suggest that mechanical injury during bTBI can cause mechanotransduced VSMC hypercontractility and phenotype switching necessary for CVS development, even in the absence of SAH. Here, we review the mechanisms by which mechanical stimulation and SAH can synergistically drive CVS progression, complicating treatment options in bTBI patients.

Mechanisms of acute brain injury after subarachnoid hemorrhage

Brain injury after subarachnoid hemorrhage (SAH) is a biphasic event with an acute ischemic insult at the time of the initial bleed and secondary events such as cerebral vasospasm 3 to 7 days later. Although much has been learned about the delayed effects of SAH, less is known about the mechanisms of acute SAH-induced injury. Distribution of blood in the subarachnoid space, elevation of intracranial pressure, reduced cerebral perfusion and cerebral blood flow (CBF) initiates the acute injury cascade. Together they lead to direct microvascular injury, plugging of vessels and release of vasoactive substances by platelet aggregates, alterations in the nitric oxide (NO)/nitric oxide synthase (NOS) pathways and lipid peroxidation. This review will summarize some of these mechanisms that contribute to acute cerebral injury after SAH.

Hypercholesterolemia increases vasospasm resulting from basilar artery subarachnoid hemorrhage in rabbits which is attenuated by Vitamin E

BACKGROUND

Aneurysm rupture results in subarachnoid hemorrhage (SAH) with subsequent vasospasm in the cerebral and cerebellar major arteries. In recent years, there has been increasing evidence that hypercholesterolemia plays a role in the pathology of SAH. It is known that hypercholesterolemia is one of the major risk factors for the development of atherosclerosis. Among the factors that have been found to retard the development of atherosclerosis is the intake of a sufficient amount of Vitamin E. An inverse association between serum Vitamin E and coronary heart disease mortality has been demonstrated in epidemiologic studies. Therefore, we tested, in an established model of enhanced cholesterol feed in rabbits, the effects of hypercholesterolemia on vasospasm after SAH by using computed tomography (CT) angiograms of the rabbit basilar artery; in addition, we tested the effects of Vitamin E on these conditions, which have not been studied up to now.

METHODS

In this study rabbits were divided into 3 major groups: control, cholesterol fed, and cholesterol + Vitamin E fed. Hypercholesterolemia was induced by a 2% cholesterol-containing diet. Three rabbit groups were fed rabbit diet; one group was fed a diet that also contained 2% cholesterol and another group was fed a diet containing 2% cholesterol and they received i.m. injections of 50 mg/kg of Vitamin E. After 8 weeks, SAH was induced by the double-hemorrhage method and distilled water was injected into cisterna magna. Blood was taken to measure serum cholesterol and Vitamin E levels. Basilar artery samples were taken for microscopic examination. CT angiography and measurement of basilar artery diameter were performed at days 0 and 3 after SAH.

RESULTS

Two percent cholesterol diet supplementation for 8 weeks resulted in a significant increase in serum cholesterol levels. Light microscopic analysis of basilar artery of hypercholesterolemic rabbits showed disturbances in the subendothelial and medial layers, degeneration of elastic fibers in the medial layer from endothelial cell desquamation, and a reduction of waves in the endothelial layer. However, the cholesterol + Vitamin E group did not exhibit these changes. The mean diameter of the basilar artery after SAH induction in the cholesterol-treated group was decreased 47% compared with the mean diameter of the control group. This value was less affected in cholesterol + Vitamin E-treated rabbits, which decreased 18% compared with the mean diameter of the control group.

CONCLUSIONS

Hypercholesterolemia-related changes in the basilar artery aggravate vasospasm after SAH. Adding Vitamin E to cholesterol-treated rabbits decreased the degree of vasospasm following SAH in the rabbit basilar artery SAH model. We suggest that Vitamin E supplements and a low cholesterol diet may potentially diminish SAH complicated by vasospasm in high-risk patients.

Intracranial hemorrhage: mechanisms of secondary brain injury

ICH is a disease with high rates of mortality and morbidity, with a substantial public health impact. Spontaneous ICH (sICH) has been extensively studied, and a large body of data has been accumulated on its pathophysiology. However, the literature on traumatic ICH (tICH) is limited, and further investigations of this important topic are needed. This review will highlight some of the cellular pathways in ICH with an emphasis on the mechanisms of secondary injury due to heme toxicity and to events in the coagulation process that are common to both sICH and tICH.

Dose-dependent ultrastructural and morphometric alterations after erythropoietin treatment in rat femoral artery vasospasm model

PURPOSE

Cerebral vasospasm is the common cause of poor outcome after aneurysmal subarachnoid hemorrhage (aSAH). Although many agents are experimentally and clinicaly used to protect or recover from vasospasm, an effective neurotherapeutic drug is still missing. Erythropoietin (EPO) is recently a promising candidate. The aim of this study is to investigate the dose-dependent effects of recombinant human EPO (rhEPO) on arterial wall in a rat femoral artery vasospasm model.

METHODS

Thirty two animals were divided into four groups: vasospasm without any treatment (group A), vasospasm +250 IU/kg rhEPO group (group B), vasospasm +500 IU/kg rhEPO group (group C), and control group (group D). Rat femoral artery vasospasm model was used. For groups B and C, 7 days of 250 IU/kg and 500 IU/kg intraperitoneal rhEPO in 0.3 ml saline were administered respectively; and for groups A and D, 0.3 ml saline were administered intraperitoneally without any treatment. After 7 days, histological and morphometric analyses were carried out.

RESULTS

Vasospasm alone group demonstrated the highest vessel wall thicknesses, comparing to other groups (p < 0.001). While for groups B and C, vessel wall thickness values were significantly higher than the control group (p < 0.001), between these two groups, there was no significant difference achieved (p > 0.05).

CONCLUSION

In our study, there was no significant difference between the two rhEPO treatment groups, but rhEPO treatment was shown to be histologically and morphometrically effective in vasospasm. However, if dosage of EPO treatment is augmented, successful results may be achieved.

The effects of dexmedetomidine dosage on cerebral vasospasm in a rat subarachnoid haemorrhage model

We investigated the effect of two different doses of dexmedetomidine on vasospasm in a rat model of subarachnoid haemorrhage (SAH). SAH was induced by injecting 0.3 mL blood into the cisterna magna in all rat groups except the control (Group C). At 1 hour and 24 hours after SAH, 5 microg/kg dexmedetomidine was given to group D5, and 10 microg/kg dexmedetomidine was given to group D10. No medication was administered to the haemorrhage group (Group H). Malondialdehyde (MDA) and paraoxonase (PON) levels were measured at 48 hours after SAH. Mean wall thickness (MWT), mean luminal diameter (MLD), and proliferating cell nuclear antigen (PCNA) expression of the basilar artery were evaluated. MDA levels and MWT were lower in the dexmedetomidine groups. The lowest MDA levels and MWT were found in Group D10. The MLD was lowest in Group H. PCNA expression was observed only in Group D10. We concluded that dexmedetomidine reduces oxidative stress and vasospasm following SAH in a dose-dependent manner.

Vascular adaptation and mechanical homeostasis at tissue, cellular, and sub-cellular levels

Blood vessels exhibit a remarkable ability to adapt throughout life that depends upon genetic programming and well-orchestrated biochemical processes. Findings over the past four decades demonstrate, however, that the mechanical environment experienced by these vessels similarly plays a critical role in governing their adaptive responses. This article briefly reviews, as illustrative examples, six cases of tissue level growth and remodeling, and then reviews general observations at cell-matrix, cellular, and sub-cellular levels, which collectively point to the existence of a "mechanical homeostasis" across multiple length and time scales that is mediated primarily by endothelial cells, vascular smooth muscle cells, and fibroblasts. In particular, responses to altered blood flow, blood pressure, and axial extension, disease processes such as cerebral aneurysms and vasospasm, and diverse experimental manipulations and clinical treatments suggest that arteries seek to maintain constant a preferred (homeostatic) mechanical state. Experiments on isolated microvessels, cell-seeded collagen gels, and adherent cells isolated in culture suggest that vascular cells and sub-cellular structures such as stress fibers and focal adhesions likewise seek to maintain constant a preferred mechanical state. Although much is known about mechanical homeostasis in the vasculature, there remains a pressing need for more quantitative data that will enable the formulation of an integrative mathematical theory that describes and eventually predicts vascular adaptations in response to diverse stimuli. Such a theory promises to deepen our understanding of vascular biology as well as to enable the design of improved clinical interventions and implantable medical devices.

Biochemomechanics of cerebral vasospasm and its resolution: I. A new hypothesis and theoretical framework

The etiology, and hence most effective treatment, of cerebral vasospasm remains unknown, thus this devastating sequela to subarachnoid hemorrhage continues to be responsible for significant morbidity and mortality. Based on abundant and diverse clinical and laboratory observations, we hypothesize that vasospasm and its subsequent resolution result from a short-term chemo-dominated turnover of cells and matrix in evolving vasoconstricted states that produces a narrowed lumen and thicker wall, which is stiffer and largely unresponsive to exogenous vasodilators, and a subsequent mechano-dominated turnover of cells and matrix in evolving vasodilated states that restores the vessel toward normal. There is, however, a pressing need for a mathematical model of arterial growth and remodeling that can guide the design and interpretation of experiments to test this and competing hypotheses. Toward this end, we present a new biochemomechanical framework that couples a 2-D model of the evolving geometry, structure, and properties of the affected arterial wall, a 1-D model of the blood flow within the affected segment, and a 0-D model of the biochemical insult to the segment. We submit that such a framework can capture salient features of the time-course of vasospasm and its potential resolution, as illustrated numerically in part II of this paper.

The effect of mexiletine on the level of lipid peroxidation and apoptosis of endothelium following experimental subarachnoid hemorrhage

OBJECTIVE

The role of apoptosis in etiopathogenesis of vasospasm is not clearly understood yet. It is widely accepted that protection of the endothelial cells from the process of apoptosis could have beneficial effects on cerebral vasospasm after subarachnoid hemorrhage (SAH). Mexiletine blocks sodium and calcium channels and activates ATP-sensitive K(+) channels. Moreover, mexiletine is known to have potent antioxidant effects through inhibiting free-radical production.

METHODS

Twenty-one rabbits were allocated into three groups randomly. Group I was sham operated group (n=7). SAH occurred but no medication was given to the Group II rabbits (SAH only group) (n=7). Mexiletine (50 mg/kg, b.i.d., i.p.) was administered just before SAH and continued until 48 hours following SAH to the Group III rabbits (Mexiletine treated group) (n=7). The ApopTag peroxidase in situ apoptosis detection kit (Serologicals Corporation, former Intergen) was used to demonstrate apoptosis in a cross section of basillary arteries. Thiobarbituric acid reactive material was used to determine the lipid peroxidation levels.

RESULTS

There was a statistically significant difference between lipid peroxidation product levels of the control and SAH only groups (p<0.05). The level of lipid peroxidation production in Mexiletine treated group was significantly lower compared with SAH only group (p<0.05) but not significantly higher than the control group (p>0.05).

DISCUSSION

In the present study we investigated the antioxidant action of mexiletine on apoptosis of endothelium following a rabbit SAH model. This experimental study directly suggested that lipid peroxidation is an important step in development of apoptosis in endothelial cells and prevention of structural integrity of endothelial cell should play a beneficial role in attenuation of cerebral vasospasm. Mexiletine treatment prevented the increase in lipid peroxidation and cerebral vasospasm. Examination of endothelial cells by staining specific for apoptosis demonstrated significant protection of cell integrity in the treated group.

Contribution of the remodeling response to cerebral vasospasm

The authors review the remodeling response of blood vessels that occurs after various injuries to arteries. The role of this response in vasospasm after subarachnoid hemorrhage (SAH) is reviewed. There is some evidence that cerebral arteries remodel after SAH in that they are less compliant and contractile than normal. Evidence for other features, such as alteration of smooth muscle phenotype, proliferation of cells and synthesis of extracellular matrix, is conflicting and requires a further study. A remodeling response probably contributes to vasospasm but the magnitude of its importance, in relation to smooth muscle contraction, which also occurs, also needs to be further defined.

Can angiographic vasospasm be used as a surrogate marker in evaluating therapeutic interventions for cerebral vasospasm?

✓ The authors tested the null hypothesis that published literature with a high level of evidence does not support the assertion that subarachnoid hemorrhage (SAH) causes cerebral vasospasm, which in turn causes cerebral infarction and poor outcome after aneurysmal SAH. The medical literature on SAH was searched in MEDLINE. The author's personal files of all published literature on SAH were reviewed. References cited in Cochrane reviews as well as the published papers that were reviewed were also retrieved.

There is no question that SAH causes what the authors have chosen to call “angiographic vasospasm.” However, the incidence and severity of vasospasm in recent series of patients is not well defined. There is reasonable evidence that vasospasm causes infarction, but again, accurate data on how severe and how diffuse vasospasm has to be to cause infarction and how often vasospasm is the primary cause of infarction are not available. There are good data on the incidence of cerebral infarction after SAH, and these data indicate that it is highly associated with poor outcome. The link between angiographic vasospasm and poor outcome is particularly poorly described in terms of what would be considered data of a high level of evidence.

The question as to whether there is a clear pathway from SAH to vasospasm to cerebral infarction to poor outcome seems so obvious to neurosurgeons as to make it one not worth asking. Nevertheless, the obvious is not always true or accurate, so it is important to note that published literature only weakly supports the causative association of vasospasm with infarction and poor outcome after SAH. It behooves neurosurgeons to document this seemingly straightforward pathway with high-quality evidence acceptable to the proponents of evidence-based medicine.

Using CT in the Diagnosis and Management of Patients with Cerebral Vasospasm

Cerebral vasospasm remains a serious complication of aneurysmal subarachnoid hemorrhage. Efforts in improving its clinical outcome have been focused on early diagnosis and applying effective treatment regimens. Standard diagnostic modalities currently used do not fully address this complex disease. The use of CT angiography and CT perfusion are discussed, with emphasis on its potential role in not only detecting vasospasm, but also in guiding management decisions and assessing clinical outcome.

Effect of targeted deletion of the heme oxygenase-2 gene on hemoglobin toxicity in the striatum

The heme oxygenase (HO) enzymes catalyze the rate-limiting step in the breakdown of heme to iron, carbon monoxide, and biliverdin. A prior cell culture study demonstrated that deletion of HO-2, the isoform constitutively expressed in neurons, attenuated hemoglobin (Hb) neurotoxicity. The present study tested the hypothesis that HO-2 gene deletion is cytoprotective in a model of Hb toxicity in vivo. Stereotactic injection of 6 microL stroma-free Hb (SFHb) into the striatum significantly increased protein oxidation in wild-type mice at 24 to 72 h, as detected by an assay for carbonyl groups. At 72 h, carbonylation was increased 2.5-fold compared with that in the contralateral striatum. In HO-2 knockout mice, protein oxidation was not increased at 24 h, and was increased by only 1.7-fold at 72 h. Similarly, striatal lipid peroxidation, as detected by the malondialdehyde assay, was significantly greater in the SFHb-injected striata of wild-type mice than in knockout mice. Striatal cell viability, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, was 45.0%+/-6.3% of that in contralateral striata in wild-type mice at 72 h; it was increased to 85%+/-8% in knockouts. Heme oxygenase-2 gene deletion did not alter weight loss or mortality after SFHb injection. Baseline striatal HO-1 expression was similar in knockout and wild-type mice; induction after SFHb injection occurred more rapidly in the latter. These results suggest that HO-2 gene deletion protects striatal cells from the oxidative toxicity of Hb in vivo. Pharmacologic or genetic strategies that target HO-2 may be beneficial after central nervous system hemorrhage, and warrant further investigation.

Dexamethasone preventing contractile and cytoskeletal protein changes in the rabbit basilar artery after subarachnoid hemorrhage

OBJECT

The aim of this project was to study the perturbations of four smooth-muscle proteins and an extracellular protein, type I collagen, after subarachnoid hemorrhage (SAH) and to examine the possible preventive effects of dexamethasone.

METHODS

Using a one-hemorrhage rabbit model, the authors first examined the effects of SAH on the expression of alpha-actin, h-caldesmon, vimentin, smoothelin-B, and type I collagen; second, they studied whether post-SAH systemic administration of dexamethasone (three daily injections) corrected the induced alterations. Measurements were obtained at Day 7 post-SAH. The proteins were studied by performing immunohistochemical staining and using a laser-scanning confocal microscope. Compared with control (sham-injured) arteries, the density of the media of arteries subjected to SAH was reduced for alpha-actin (-11%, p = 0.01) and h-caldesmon (-15%, p = 0.06) but increased for vimentin (+15%, p = 0.04) and smoothelin-B (+53%, p = 0.04). Among animals in which SAH was induced, arteries in those treated with dexamethasone demonstrated higher values of density for alpha-actin (+13%, p = 0.05) and h-caldesmon (+20%, p = 0.01), lower values for vimentin (-55%, p = 0.05), and nonsignificantly different values for smoothelin-B. The density of type I collagen in the adventitia decreased significantly after SAH (-45%, p = 0.01), but dexamethasone treatment had no effect on this decrease.

CONCLUSIONS

The SAH-induced alterations in the density of three of four smooth-muscle proteins were prevented by dexamethasone treatment; two of these proteins--alpha-actin and h-caldesmon--are directly related to contraction. This drug may potentially be useful to prevent certain morphological and functional changes in cerebral arteries after SAH.

Molecular profile of vascular ion channels after experimental subarachnoid hemorrhage

Cerebral vasospasm is a transient, delayed constriction of cerebral arteries that occurs after subarachnoid hemorrhage (SAH). Smooth muscle cells show impaired relaxation after SAH, which may be caused by a defect in the ionic mechanisms regulating smooth muscle membrane potential and Ca(2+) permeability. We tested this hypothesis by examining changes in expression of mRNA and protein for ion channels in the basilar arteries of dogs after SAH using quantitative real-time polymerase chain reaction (PCR) and western blotting. SAH was associated with a significant reduction in basilar artery diameter to 41 +/- 8% of pre-SAH diameter (P < 0.001) after 7 days. There was significant downregulation of the voltage-gated K(+) channel K(v) 2.2 (65% reduction in mRNA, P < 0.001; 49% reduction in protein, P < 0.05) and the beta1 subunit of the large-conductance, Ca(2+) - activated K(+) (BK) channel (53% reduction in mRNA, P < 0.02). There was no change in BK beta1 subunit protein. Changes in mRNA levels of K(v) 2.2 and the BK-beta1 subunit correlated with the degree of vasospasm (r(2) = 0.490 and 0.529 respectively, P < 0.05). The inwardly rectifying K(+) (K(ir)) channel K(ir) 2.1 was upregulated (234% increase in mRNA, P < 0.001; 350% increase in protein, P < 0.001). There was no significant change in mRNA expression of L- type Ca(2+) channels and the BK-alpha subunit. These data suggest that K(+) channel dysfunction may contribute to the pathogenesis of cerebral vasospasm.

The effect of EGb-761 on morphologic vasospasm in canine basilar artery after subarachnoid hemorrhage

This study investigated the effects of Ginkgo biloba extract (EGb-76l), an anti-oxidant and platelet-activating factor antagonist, on basilar artery vasospasm in an experimental canine subarachnoid hemorrhage model. Morphometric analyses were performed, and serum and cerebrospinal fluid endothelin-l levels were measured by radioimmunoassay. Comparisons were made between treated and untreated groups. Twenty-four mongrel dogs were randomly assigned to three groups. The animals in group 1 (n = 8) were not subjected to subarachnoid hemorrhage and received no treatment. In this group, serum and cerebrospinal fluid endothelin-l levels were measured daily for 8 days. On day 9, the animals were killed and their basilar arteries were excised for histopathological examination. In group 2 (n = 8), subarachnoid hemorrhage was produced using autologous arterial blood, and daily intravenous boluses of saline were administered for the next 8 days. Assessments of endothelin-l levels and the basilar arteries were performed as described for group 1. In group 3 (n = 8), subarachnoid hemorrhage was produced using autologous arterial blood, and daily intravenous boluses of EGb-761 were administered for 8 days. Endothelin-1 levels and the basilar arteries were assessed as described above. The groups' serum endothelin-1, cerebrospinal fluid endothelin-1, and histopathological findings were compared. In group 1, the serum and cerebrospinal fluid endothelin-1 levels did not change significantly over the 8 days, and histopathological examination of the basilar arteries revealed no abnormalities. In group 2, the serum and cerebrospinal fluid endothelin-1 levels increased abruptly and significantly on day 2, and remained high to the end of the study period (day 8). Histopathological examination revealed marked vasospasm. In group 3, the serum and cerebrospinal fluid endothelin-1 levels followed the same pattern observed in group 2; however, the arteries showed significantly less vasospasm than that observed in group 2. The study findings did not provide information about the mechanism of action of the platelet-activating factor-antagonist EGb-761, but they clearly show that this agent decreases morphologic vasospasm in the dog basilar artery.

Attenuation of hemolysate-induced cerebrovascular endothelial cell injury and of production of endothelin-1 and big endothelin-1 by an endothelin-converting enzyme inhibitor

BACKGROUND

Endothelin-1 (ET-1) is a potent and long-acting vasoconstrictive peptide that has been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). ET-1 has been shown to be present in the cerebrospinal fluid of patients after SAH, and substances produced during hemolysis of subarachnoid blood clots are believed to be responsible for stimulating the production of ET-1. The biosynthesis of ET-1 is a multi-step process, involving the conversion of the relatively inactive precursor big ET-1 to the mature peptide by endothelin converting enzyme (ECE), a metalloprotease. Consequently, ECE inhibitors are expected to suppress the biosynthesis of ET-1 and reduce the pathologic impact resulting from overproduction of this peptide. The purpose of the present study was to investigate the effects of an ECE inhibitor, CGS 26303, on hemolysate-induced injury of cerebral vessel endothelial cells as well as the production of ET-1 from these cells.

METHODS

Different doses of CGS 26303 and hemolysate were added to the culture medium for 48 hours. Cell injury was assessed by cell morphology and density, while the productions of ET-1 and big ET-1 were determined by radioimmunoassays.

RESULTS

Hemolysate alone increased the levels of ET-1 and big ET-1 in culture medium and caused substantial cell loss. Treatment with CGS 26303 inhibited the hemolysate-induced increases in the levels of ET-1 and big ET-1 and reduced endothelial cell injury. The protective effects of CGS 26303 were modest when this inhibitor was added simultaneously with hemolysate, but were prominent and dose-dependent when the inhibitor was given 30 minutes before the addition of hemolysate.

CONCLUSION

These results suggest that overproduction of ET-1 contributes significantly to hemolysate-induced damage to cerebrovascular endothelial cells.

Morphological changes of cerebral arteries in a canine double hemorrhage model

Cerebral vasospasm is a major cause of morbidity and mortality in patients suffering from subarachnoid hemorrhage (SAH). Despite numerous studies, the pathogenesis of this deadly disorder is not clearly understood. Alterations in endothelial cells are a distinct morphological feature of cerebral vasospasm and some recent studies suggest that apoptosis might play a role in the cells' death. The goal of the present study is to examine the time course of apoptosis in endothelial cells of spastic cerebral arteries following experimental subarachnoid hemorrhage. Fifteen dogs were used in the present study. Twelve of them were divided into three groups (four per group) and subjected to a double-hemorrhage method of SAH. Following SAH, groups were sacrificed respectively on days 3, 5, and 7. Three dogs served as controls without blood injection. The basilar arteries were studied with the transmission electron microscopy and with angiography. Angiographic vasospasm began on day 3 and peaked on day 7. In morphologic studies, control dogs did not demonstrate apoptotic-like changes in endothelial cells of the basilar arteries. Beginning with day 3, apoptotic-like changes were noted in endothelial cells and consisted of condensation of peripheral nuclear chromatin, blebbing of the cell membrane, and condensation of the cytoplasm. Such changes progressed with time and were maximally developed by day 7. This is the first study that demonstrates the time course of apoptotic-like changes in the endothelial cells in the vasospastic basilar artery. Apoptosis might play an important role in the pathogenesis of vasospasm.

Preliminary study of the effects of caspase inhibitors on vasospasm in dog penetrating arteries

This preliminary study was undertaken to explore the possible protective effect of caspase inhibitors Z-VDVAD-FMK and Z-DEVD-FMK in apoptosis and vasospasm in penetrating arteries during cerebral vasospasm. Experimental subarachnoid hemorrhage (SAH) was induced in 16 dogs by an intracisternal injection of autologous arterial blood (0.4 ml/kg) on Day 0 and Day 2. The dogs were then randomly divided into four groups: control-SAH, vehicle-control, and two treatment groups. In the treatment groups, caspase inhibitors (10 microM) were intracisternally injected each day beginning on Day 2 until Day 6. Effects of the inhibitors were analyzed utilizing angiography, the clinical status of the dogs (activity, appetite, and neurological deficits), and transmission electron microscopy of the penetrating arteries. All the dogs were sacrificed on Day 7. In control-SAH and vehicle-control groups, severe angiographic vasospasm, poor clinical status, and penetrating vasospasm were registered in all the dogs. In the treatment groups, all the dogs developed angiographic vasospasm and vasospasm in penetrating arteries, however, with benign clinical statues. The occurrence of apoptosis in endothelial cells was reduced by caspase-2 but not by caspase-3 inhibitor. Caspase inhibitors failed to prevent vasospasm either in major or in penetrating arteries. The improvement of clinical scores by the caspase inhibitors may be related to their protection of the endothelial cells. Further investigations using more rigorous clinical scoring system and quantitative information on the degree of apoptosis in the vessels, as well as in the brain parenchyma are recommended.

Sustained arterial narrowing after prolonged exposure to perivascular endothelin

OBJECTIVE

The vasoconstrictor peptide endothelin-1 (ET-1) produces narrowing of cerebral arteries and has been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. Little is known, however, regarding the physiological consequences of prolonged exposure of arterial wall to ET-1.

METHODS

In 30 rats, normal saline or 10(-8) mol/h of ET-1 was continuously applied for 3 or 5 days to the adventitial surface of the femoral artery in a Silastic cuff via an osmotic infusion pump. Vessels were examined for histopathological changes and luminal narrowing during ET-1 infusion (3 or 5 d) or at intervals from 2 to 9 days after infusion was stopped.

RESULTS

Marked arterial constriction (30-40% arterial diameter reduction) was present during continuous ET-1 infusion for 3 or 5 days. For both 3- and 5-day ET-1 infusions, significant reduction in arterial cross sectional area persisted up to 4 days after cessation of infusion, after which normal caliber returned. In arteries with persistent luminal narrowing after cessation of ET-1 infusion, light microscopic findings revealed morphological changes in the vessel wall similar to those observed in cerebral vasospasm after subarachnoid hemorrhage, with apparent increased collagen deposition in media and adventitia.

CONCLUSION

Continuous infusion of ET-1 produces reversible arterial narrowing that persists beyond the usual interval of physiological effect for this agent. Prolonged arterial constriction may produce physiological changes in arterial wall that act to maintain a narrowed lumen.

Cerebrovascular inflammation following subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage frequently results in complications including intracranial hypertension, rebleeding and vasospasm. The extravasated blood is responsible for a cascade of reactions involving release of various vasoactive and pro-inflammatory factors (several of which are purported to induce vasospasm) from blood and vascular components in the subarachnoid space. The authors review the available evidence linking these factors to the development of inflammatory lesions of the cerebral vasculature, emphasizing: 1) neurogenic inflammation due to massive release of sensory nerve neuropeptides; 2) hemoglobin from lysed erythrocytes, which creates functional lesions of endothelial and smooth muscle cells; 3) activity, expression and metabolites of lipoxygenases cyclooxygenases and nitric oxide synthases; 4) the possible role of endothelin-1 as a pro-inflammatory agent; 5) serotonin, histamine and bradykinin which are especially involved in blood-brain barrier disruption; 6) the prothrombotic and pro-inflammatory action of complement and thrombin towards endothelium; 7) the multiple actions of activated platelets, including platelet-derived growth factor production; 8) the presence of perivascular and intramural macrophages and granulocytes and their interaction with adhesion molecules; 9) the evolution, origins, and effects of pro-inflammatory cytokines, especially IL-1, TNF-alpha and IL-6. Human and animal studies on the use of anti-inflammatory agents in subarachnoid hemorrhage include superoxide and other radical scavengers, lipid peroxidation inhibitors, iron chelators, NSAIDs, glucocorticoids, and serine protease inhibitors. Many animal studies claim reduced vasospasm, but these effects are not always confirmed in human trials, where symptomatic vasospasm and outcome are the major endpoints. Despite recent work on penetrating vessel constriction, there is a paucity of studies on inflammatory markers in the microcirculation.

Oxyhemoglobin induces caspase-mediated cell death in cerebral endothelial cells

Damaged endothelium is one of the pathological changes of the cerebral vasospastic vessels following subarachnoid hemorrhage. Our recent study shows that oxyhemoglobin (OxyHb) induces apoptosis in vascular endothelial cells. Apoptosis generally requires the action of various classes of proteases, including a family of cysteine proteases, known collectively as the caspases. This study was undertaken to investigate the activation of caspases and the efficacy of caspase inhibitors, z-IETD-fmk and z-LEHD-fmk, for oxyhemoglobin-induced apoptosis in vascular endothelial cells. Cultured bovine brain microvascular endothelial cells (passages 5-9) were used for this study. OxyHb (10 micromol/L) was added during the 24-72 h incubation with and without caspase-8 or - 9 inhibitors (z-IETD-fmk and z-LEHD-fmk). Counting surviving cells, DNA laddering, western blotting of poly(ADP-ribose) polymerase, and measurement of caspase activities were employed to confirm the cytotoxic effects of OxyHb and the protective effects of the caspase inhibitors. OxyHb produced cell detachment in a time-dependent manner and increased caspase-8 and -9 activities in the cells. z-IETD-fmk and z-LEHD-fmk (100 micromol/L) attenuated OxyHb-induced cell loss, DNA laddering, and proteolytic cleavage of PARP, although a lower concentration (10 micromol/L) of caspase inhibitors showed partial effects. OxyHb activates caspase-8 and -9 in cultured vascular endothelial cells, and blocking the action of the caspases with the inhibitors efficiently prevents loss of vascular endothelial cells from OxyHb-induced apoptosis in vitro. These results suggest that the caspase cascade participates in OxyHb-induced apoptosis.

The selectin superfamily: the role of selectin adhesion molecules in delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage

Cerebral ischaemia and reperfusion injury may be exacerbated by leukocyte recruitment and activation. Adhesion molecules play a pivotal role in leukocyte recruitment. We report a prospective study of the potential role of the selectin family of adhesion molecules (E-, P- and L-selectin) in delayed cerebral ischaemia (DID) following aneurysmal subarachnoid haemorrhage. In patients with good grade SAH, we have compared serum concentrations of E-, P- and L-selectin, between patients who do, and do not develop delayed cerebral ischaemia. There was no difference in E-selectin concentration between the two groups (44.0 ng/ml vs. 37.4 ng/ml). Serum P-selectin concentration was significantly higher in patients with DID compared to those patients without DID (149.5 ng/ml vs. 112.9 ng/ml, p = 0.039). Serum L-selectin concentrations were significantly lower in patients with DID (633.8 ng/ml vs 897.9 ng/ml, p = 0.013). We conclude that P- and L-selectin are involved in the pathogenesis of DID following aneurysmal subarachnoid haemorrhage. The results of this study do not elucidate the exact role of each selectin in DID.

Broad-spectrum and selective serine protease inhibitors prevent expression of platelet-derived growth factor-BB and cerebral vasospasm after subarachnoid hemorrhage: vasospasm caused by cisternal injection of recombinant platelet-derived growth factor-BB

BACKGROUND AND PURPOSE

Plasma serine protease cascade, including the complement system and thrombin, is activated in the subarachnoid space during the acute phase after subarachnoid hemorrhage (SAH). To examine the effect of protease cascade-based inflammation and subsequent vascular repair in the development of cerebral vasospasm, we examined the effect of 2 synthetic serine protease inhibitors-FUT-175, an inhibitor of thrombin and the complement system, and argatroban, a selective inhibitor of thrombin-on the development of cerebral vasospasm in a rabbit SAH model.

METHODS

One hundred Japanese White male rabbits were used in the study. The SAH was simulated by a single injection of autologous arterial blood into the cisterna magna. To evaluate the development of cerebral vasospasm, the caliber of the basilar artery was measured on x-ray film before and at 2 days after SAH. Nine groups of rabbits (n=6 each) were treated with continuous intravenous injection of FUT-175 (2.5, 5, 10, or 20 mg/d), argatroban (1.25, 2.5, or 5 mg/d), or the same amount of saline (vehicle) for 48 hours, starting 40 minutes after SAH. Two days after SAH, the expression of homodimer of platelet-derived growth factor-BB (PDGF-BB) in the basilar artery was examined with immunohistochemical techniques. In 20 normal rabbits, 5 microg of recombinant PDGF-BB or vehicle was injected into the cisterna magna, and the basilar arteries were examined on angiograms for 48 hours.

RESULTS

Significant differences were observed in the caliber of the basilar arteries between the vehicle group and the groups with the 3 larger doses of FUT-175 (vehicle, 52+/-5.0%; 5 mg, 79+/-5.7%; 10 mg, 80+/-2.5%; 20 mg, 80+/-3.7%) and between the vehicle group and the groups with the 2 larger doses of argatroban (vehicle, 52+/-6.4%; 2.5 mg, 81+/-9.0%; 5 mg, 85+/-4.1%) (P<0.05). In the histological examination, administration of effective doses of FUT-175 or argatroban suppressed the expression of PDGF-BB in the endothelial and medial smooth muscle cell layers. Exogenous PDGF-BB caused delayed and prolonged vasoconstriction on normal basilar arteries.

CONCLUSIONS

Activation of the serine protease cascade and/or thrombin after SAH was demonstrated to play an essential role in the development of cerebral vasospasm. The expression of PDGF-BB-like protein in the arterial walls correlated with the development of cerebral vasospasm. Elevated PDGF-BB level in the subarachnoid space was found to induce delayed and chronic vasoconstriction.

Confocal microscopic evidence of decreased alpha-actin expression within rabbit cerebral artery smooth muscle cells after subarachnoid haemorrhage

Our objective was to determine whether subarachnoid haemorrhage modifies cerebral artery smooth muscle cell phenotype and the contractile protein alpha-actin measured 7 days after haemorrhage. We used a rabbit subarachnoid haemorrhage model and immunofluorescence labelling of alpha-smooth muscle actin, vimentin and desmin. The paired comparison between the haemorrhage and sham rabbits was performed using confocal laser-scanning microscopy. We found in the haemorrhage group significantly less intense alpha-actin immunostaining (p = 0.036) and more intense vimentin immunostaining (p = 0.043) but no significant change in the intensity of desmin staining. Our results indicate an absolute decrease after subarachnoid haemorrhage in the amount of functional alpha-actin and in the light of the literature may suggest a certain degree of dedifferentiation of smooth muscle cells in the cerebral artery wall.

Expression of endothelial nitric oxide synthase after exposure to perivascular blood

OBJECTIVE

Although nitric oxide (NO) has been implicated in the development of vasospasm after subarachnoid hemorrhage, little is known regarding the time course of NO synthesis in vessel wall after exposure to perivascular blood. This study measures temporal characteristics of changes in vessel wall NO synthesis.

METHODS

Rat femoral arteries exposed to perivascular blood for 3, 5, or 7 days were assayed for the endothelial isoform of NO synthase (eNOS) by Western blot testing. Additionally, rat femoral arteries exposed to perivascular blood for intervals from 3 to 14 days were analyzed by means of immunohistochemistry for eNOS.

RESULTS

Semiquantitative densitometry of femoral artery Western blots demonstrated a biphasic pattern of eNOS expression after exposure to perivascular blood. Compared with control arteries, eNOS expression increased at 3 days (53 +/- 36%), normalized at 5 days (-6 +/- 7%), and decreased by 7 days (-39 +/- 15%). Immunohistochemistry confirmed the changes in expression of immunoreactive eNOS in femoral endothelium during the first week after chronic perivascular blood exposure and apparent reduced eNOS immunostaining, which persisted up to 14 days after application of blood.

CONCLUSION

The expression of endothelial-derived NO in rat femoral artery exposed to perivascular whole blood does not directly correlate with changes in vessel caliber during this interval. The biphasic expression of eNOS observed in these experiments highlights the complexity of processes occurring in the vicinity of the vessel wall during vasospasm and may be related to several mechanisms that modulate vessel tone and response to injury.

Rebamipide prevents periarterial blood-induced vasospasm in the rat femoral artery model

We examined the effect of rebamipide on the vasospasm induced by periarterial blood. In the in vitro study, the significant production of superoxide anion that was identified 3 hours after application of 10% whole blood to the rat aortic segments was inhibited by rebamipide (100 and 300 microM) and these results were correlated with the in vitro intercellular adhesion molecule-1 (ICAM-1) expression on the femoral artery. In the in vivo study, there was an increased mobilization of granulocytes in parallel with a large expression of ICAM-1 in the vessels 24 hours after periarterial blood was applied to the femoral artery which then declined. Subsequently, infiltration of macrophages progressively increased at all layers 7-12 days after application. Pretreatment with rebamipide (100 and 300 mg kg(-1) day(-1), p.o.) significantly inhibited the morphological changes as well as the expression of ICAM-1 with inhibition of granulocyte/macrophage mobilization. In association with these findings, increased wall thickness and decreased lumen area were significantly inhibited by pretreatment with rebamipide. These results provide valuable information for the therapeutic use of rebamipide to relieve vascular remodeling induced by periarterial blood.

Caspase inhibitors attenuate oxyhemoglobin-induced apoptosis in endothelial cells

BACKGROUND AND PURPOSE

Our recent study showed that oxyhemoglobin (OxyHb) induces apoptosis in cultured endothelial cells. Apoptosis requires the action of various classes of proteases, including a family of cysteine proteases known collectively as the caspases. This study was undertaken to investigate the effect of 2 caspase inhibitors, Z-VDVAD-FMK and Z-DEVD-FMK, in the protection of endothelial cells from OxyHb-induced apoptosis.

METHODS

Cultured bovine brain microvascular endothelial cells (passages 5 to 9) were exposed to OxyHb (10 micromol/L) for 24 to 72 hours with and without caspase inhibitors. Cell attachment, DNA ladder, Western blotting of poly(ADP-ribose) polymerase (PARP), and caspase activities were measured to confirm the cytotoxic effect of OxyHb and the protective effect of the caspase inhibitors.

RESULTS

(1) OxyHb produced cell detachment in a time-dependent manner. (2) OxyHb increased caspase-2 and -3 activities, produced DNA ladders, and cleaved PARP in endothelial cells. (3) Z-VDVAD-FMK and Z-DEVD-FMK (100 micromol/L) attenuated OxyHb-induced cell detachment, reduced caspase-2 and -3 activities, abolished OxyHb-induced DNA ladders, and prevented OxyHb-induced cleavage of PARP.

CONCLUSIONS

OxyHb activates caspase-2 and -3 in cultured brain microvessel endothelial cells. Caspase inhibitors attenuated the cytotoxic effect of OxyHb.

Quantitative analysis of gene expressions related to inflammation in canine spastic artery after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The possible role of inflammatory reaction of the cerebral artery in the pathogenesis of cerebral vasospasm has been noted in recent studies. We quantitatively measured the levels of expression of genes related to inflammation in the spastic artery in a canine double-hemorrhage model.

METHODS

Twenty dogs were assigned to 4 groups: group D0, control; group D2, dogs killed 2 days after cisternal injection of blood; group D7, dogs given double cisternal injections of blood and killed 7 days after the first injection; and group D14. Angiography was performed twice: on the first day and before the animals were killed. Total RNA was extracted from the basilar artery. The expressions of interleukin (IL)-1alpha, IL-6, IL-8, IL-10, tumor necrosis factor-alpha, E-secretin, fibronectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule-1, transforming growth factor-ss, basic fibroblast growth factor, and collagen types I, III, and IV were examined with TaqMan real-time quantitative reverse transcription-polymerase chain reaction.

RESULTS

Prolonged arterial narrowing peaking on 7 day was observed. There was a significant difference in vessel caliber between D0, D2, D7, and D14 groups (P:<0.0001). There were significant differences in mRNA expression in the basilar artery for IL-1alpha, IL-6, IL-8, ICAM-1, and collagen type I between D0, D2, D7, and D14 groups (P:=0.0079, 0. 0196, 0.0040, 0.0017, and <0.0001, respectively). The average level of mRNA was highest in D7 for IL-1alpha, IL-6, IL-8, and ICAM-1 (17-, 16-, 131-, and 1.7-fold compared with those of D0, respectively) and in D14 for collagen type I (10.9-fold).

CONCLUSIONS

Increased expression of genes related to inflammation in the spastic artery suggests that inflammatory reaction of the cerebral artery is associated with sustained contraction.

Effects of mitogen-activated protein kinase inhibitors on cerebral vasospasm in a double-hemorrhage model in dogs

OBJECT

Mitogen-activated protein kinase (MAPK) may be involved in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. This study was conducted to investigate the ability of the MAPK inhibitors PD-98059 and U-0126 to reverse vasospasm in a double-hemorrhage model in dogs.

METHODS

Twenty-two adult mongrel dogs of either sex, each weighing 18 to 24 kg, were divided randomly into four groups: control SAH (four dogs), vehicle- (dimethyl sulfoxide, six dogs), PD-98059- (six dogs), and U-0126-treated groups (six dogs). The double-hemorrhage model was created by an autologous blood injection into the cisterna magna on Days 0 and 2. An intracisternal injection of MAPK inhibitors was administered once per day on Days 3 through 6. Cerebral angiography was performed on Days 0 and 7 before the animals were killed. Western blot analysis was used to study the effects of hemorrhage and drug treatment on the MAPK immunoprecipitation. Severe vasospasm developed in the dogs in the control and vehicle-treated groups (basilar artery [BA] diameter reduction 46.6 +/- 5.5% and 49.3 +/- 4.6%, respectively). In the PD-98059-treated group, most of the dogs developed mild vasospasm (18.9 +/- 6.2%). In the U-0126-treated group, severe vasospasm was observed despite treatment (39.6 +/- 6.4%). The PD-98059 but not the U-0126 abolished MAPK immunoprecipitation in the spastic BAs. However, treatment with either PD-98059 or U-0126 improved the clinical scores of the dogs.

CONCLUSIONS

The present study is the first in which the effects of MAPK inhibitors on vasospasm have been investigated in vivo. The authors demonstrate that MAPK may play a role in vasospasm and that PD-98059 is a potential candidate for the treatment of cerebral vasospasm.

Role of calcium channels in oxyhemoglobin-induced apoptosis in endothelial cells

OBJECT

Oxyhemoglobin (OxyHb) released from hemolysed erythrocytes has been considered to be responsible for cerebral vasospasm after subarachnoid hemorrhage. The authors previously reported that OxyHb produced apoptosis in cultured vascular endothelial cells. The change in intracellular Ca++ homeostasis was expected to be one of the possible mechanisms of the cytotoxic effects of OxyHb. This study was undertaken to investigate the protective effects of Ca++ channel blockers on OxyHb-induced apoptosis.

METHODS

Cultured bovine coronary artery and brain microvascular endothelial cells (passages 5-9) were used. A cell density study, immunohistochemical staining, and DNA fragmentation analysis were performed to confirm apoptosis. Various concentrations (1-50 microM) of OxyHb were used for 24- to 72-hour incubations with and without Ca++-channel blockers. Oxyhemoglobin produced cytotoxicity leading to cell detachment from the culture dish in time- and concentration-dependent manners. The highest dose (50 microM) of OxyHb produced cell detachment after a 24-hour incubation, and the lower doses (1-10 microM) produced cell detachment after 48 to 72 hours. Immunohistochemical analysis showed that apoptosis occurred in cells that were still attached to the side of the culture dish after 48 to 72 hours of OxyHb treatment (5 microM). The OxyHb (10 microM) produced DNA ladders at 48 to 72 hours. Three Ca++-channel blockers were used to prevent the toxic effect of OxyHb. The voltage-dependent Ca++-channel blocker nicardipine (1 microM), the voltage-independent Ca++-channel blocker econazole (10 microM), and the inorganic Ca++-channel blocker lanthanum (100 microM) all failed to prevent cell detachment or DNA ladders produced by OxyHb. These results were similar in both cell lines.

CONCLUSIONS

Oxyhemoglobin produced apoptotic changes in cultured vascular endothelial cells, and Ca++-channel blockers did not prevent OxyHb-induced apoptosis.

Morphological changes of cerebral penetrating arteries in a canine double hemorrhage model

BACKGROUND

Morphological presentations of cerebral vasospasm, such as dystrophy and desquamation of endothelial cells, corrugation of the internal elastic layer, and necrotic changes in smooth muscle cells, are well defined in large cerebral arteries. This study was undertaken to examine pathological changes in cerebral penetrating arteries in a canine double hemorrhage model.

METHODS

Eighteen mongrel dogs were subjected to an autologous arterial blood (0.4 mL/kg) injection into the cisterna magna on day 0 and day 2 after withdrawal of an equivalent amount of cerebrospinal fluid. Angiogram was performed on day 0 before the blood injection and on the day the dogs were sacrificed. The dogs were divided into four groups: control (day 0) (n = 4), hemorrhage and sacrificed on day 3 (n = 4), day 5 (n = 5), and day 7 (n = 5). The penetrating arteries were removed and found to be spastic on days 3, 5, and 7, but not in the control group.

RESULTS

Endothelial dystrophy and partial desquamation were recorded in all dogs sacrificed on days 5 and 7. Condensation of chromatin, blebbing of the membrane, and condensation of cytoplasm were identified in many endothelial cells, features that are consistent with apoptosis. The morphological changes in the penetrating arteries were more pronounced on days 5 and 7.

CONCLUSIONS

Vasospasm occurred in cerebral penetrating arteries in a canine double hemorrhage model. The morphological change in penetrating arteries, especially apoptosis in endothelial cells, is consistent with an early phase of vasospasm. Vasospasm in a penetrating artery may contribute to the cerebral ischemia that occurs during vasospasm.

Apoptosis of endothelial cells in vessels affected by cerebral vasospasm

BACKGROUND

Cerebral vasospasm after subarachnoid hemorrhage is a prolonged contraction that leads to cerebral ischemia or infarction. Morphological studies of cerebral arteries during vasospasm have shown extensive necrosis of smooth-muscle cells and desquamation and dystrophy of endothelial cells. The mechanism of cellular death is unknown.

METHODS

We report an observation of apoptotic changes in the cerebral arteries of a patient who died after suffering severe cerebral vasospasm caused by aneurysmal rupture. Subarachnoid hemorrhage and cerebral vasospasm were confirmed by computed tomography scanning and angiogram. Histological and immunohistological examinations for apoptosis were performed in cerebral arteries. For control, the arteries from another patient, who died of trauma without head injury, were used.

RESULTS

Corrugation of the internal elastic lamina and increased amounts of connective tissue was demonstrated by light microscopy. Apoptotic changes, characterized by condensation of chromatin of the nucleus and detachment from the basal membrane, were found on transmission electron microscopy in endothelial cells. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling reaction revealed positive staining of the nuclei of the endothelial cells.

CONCLUSIONS

This study demonstrates that apoptosis occurred in the cerebral arteries in a patient who died of cerebral vasospasm. The possible role of apoptosis in cerebral vasospasm is discussed.

Effects of the radical scavenger AVS on behavioral and BBB changes after experimental subarachnoid hemorrhage

Free radicals are important contributors to the global brain dysfunction that follows subarachnoid hemorrhage (SAH). We evaluated the effects of hydroxyl radical scavenger AVS [(+/-)-N,N'-propylenedinicotinamide; Nicaraven] after experimental SAH on rodent behavioral deficits (employing a battery of well-characterized assessment tasks over a 2-day observation period) and blood-brain barrier (BBB) permeability changes two days after SAH (quantifying the microvascular alterations according to the extravasation of protein-bound Evans Blue using a spectrophotofluorimetric technique) in dose-response and time-window experiments. Groups of 10 rats were injected with 400 microl of autologous blood into the cisterna magna, and followed by intravenous continuous infusion of saline or 0.1, 03 or 1 mg/kg/min of AVS beginning within 5 minutes or 6 or 12 hours after SAH. The results were compared with sham-operated saline-treated and with SAH saline-treated animals. AVS significantly ameliorated performances on Beam Balance (p < 0.01) and decreased BBB permeability changes in frontal, temporal, parietal, occipital and cerebellar cortices and subcortical and cerebellar nuclei and brainstem (p < 0.01), but did not significantly affect changes in Beam Walking. This study demonstrates the neuroprotective effects of AVS when administered after experimental SAH in rats. These effects were dose-dependent and, moreover, were evident within the therapeutic window of 6-12 hours after SAH. These results reinforce the concept of a participation of reactive oxygen intermediates in the cerebral dysfunction following SAH.