Evidence of the role of hemolysis in experimental cerebral vasospasm

Dental Pulp Stem Cell-Derived Conditioned Medium Alleviates Subarachnoid Hemorrhage-Induced Microcirculation Impairment by Promoting M2 Microglia Polarization and Reducing Astrocyte Swelling

Aneurysmal subarachnoid hemorrhage (SAH) can cause severe neurological deficits and high mortality. Early brain edema following SAH contributes to the initiation of microcirculation impairment and may further lead to delayed ischemic neurologic deficit (DIND). This study aimed to investigate whether dental pulp stem cell conditioned medium (DPSC-CM) ameliorates SAH-induced microcirculation impairment and the underlying mechanisms. SAH was induced via intrathecal injection of fresh autologous blood in Wistar male adult rat. DPSC-CM or DPSC-CM + insulin growth factor-1 (IGF-1) antibody was randomly administered by intrathecal route 5 min after SAH induction. To evaluate the underlying mechanisms of DPSC-CM in the treatment of SAH, primary rat astrocyte and microglia co-cultures were challenged with hemolysate or SAH-patient CSF in the presence or absence of DPSC-CM. The results showed that in vivo, DPSC-CM treatment decreased the brain water content, improved microcirculation impairment and enhanced functional recovery at 24 h post-SAH. DPSC-CM treatment also alleviated the expressions of water channel protein aquaporin-4 (AQP4) and pro-inflammatory cytokines, and enhanced the expressions of anti-inflammatory factors in the cortical region. However, all the beneficial effects of DPSC-CM were abrogated after treatment with IGF-1 neutralizing antibody. The in vitro results further showed that DPSC-CM treatment reduced hemolysate/SAH-patient CSF-induced astrocyte swelling and promoted M2 microglia polarization, partially through IGF-1/AKT signaling. The data suggested that DPSC-CM significantly reduced brain edema and rescued microcirculation impairment with concomitant anti-inflammatory benefits after SAH, and may potentially be developed into a novel therapeutic strategy for SAH.

Arginase-1 Released into CSF After Aneurysmal Subarachnoid Hemorrhage Decreases Arginine/Ornithine Ratio: a Novel Prognostic Biomarker

We hypothesized that the enzyme arginase-1 is released into the cerebrospinal fluid (CSF) during red blood cell lysis and contributes to dysregulated metabolism of the nitric oxide (NO) precursor L-arginine during aneurysmal subarachnoid hemorrhage (SAH). This prospective case-control study included 43 patients with aneurysmal SAH and ventricular drainage for clinical reasons. Longitudinal CSF samples (99) were obtained in the course of SAH. Patients were dichotomized regarding the occurrence of cerebral vasospasm syndrome (CVS) (N = 19). Arginase-1 and the amino acids L-arginine and L-ornithine were quantified in CSF. Outcome assessments included delayed cerebral ischemia (DCI) and functional status after 3 months using the modified Rankin Scale (mRS). Arginase-1 was released into the CSF of SAH patients whereas this enzyme was undetectable in controls. Compared to patients without CVS, arginase-1 levels were higher in CVS patients until day 14 after clinical event. The well-known surrogate parameter for arginase acitivity, the L-arginine to L-ornithine ratio (Arg/Orn), correlated with CSF arginase-1 levels. Arg/Orn was reduced in patients with CVS from disease onset (days 1-3, p = 0.0009) until day 14. Logistic regression analysis of early Arg/Orn was predictive for CVS (p = 0.008) and DCI (p = 0.035), independent of age, Hunt and Hess grade, and intraventricular blood. Arg/Orn < 2.71 at disease onset predicted CVS with a sensitivity of 86.7% and specificity of 72.2%. Arg/Orn ≥ 2.71 predicted excellent functional outcome. We propose a novel mechanism contributing to NO deprivation during SAH: arginase-1 is released from erythrocytes into the CSF, leading to L-arginine consumption and reduced NO bioavailability. Furthermore, Arg/Orn is a robust predictor for occurrence of CVS, DCI, and functional outcome 3 months after aneurysmal SAH. Our data provide a novel prognostic biomarker and may contribute to the development of novel therapeutic strategies in SAH. Clinical Trial Registration-URL: http://www.drks.de . Unique identifier: DRKS00015293, date of registration: 13.09.2018.

Therapeutically Targeting Platelet-Derived Growth Factor-Mediated Signaling Underlying the Pathogenesis of Subarachnoid Hemorrhage-Related Vasospasm

INTRODUCTION

Vasospasm accounts for a large fraction of the morbidity and mortality burden in patients sustaining subarachnoid hemorrhage (SAH). Platelet-derived growth factor (PDGF)-β levels rise following SAH and correlate with incidence and severity of vasospasm.

METHODS

The literature was reviewed for studies investigating the role of PDGF in the pathogenesis of SAH-related vasospasm and efficacy of pharmacological interventions targeting the PDGF pathway in ameliorating the same and improving clinical outcomes.

RESULTS

Release of blood under high pressure into the subarachnoid space activates the complement cascade, which results in release of PDGF. Abluminal contact of blood with cerebral vessels increases their contractile response to PDGF-β and thrombin, with the latter upregulating PDGF-β receptors and augmenting effects of PDGF-β. PDGF-β figures prominently in the early and late phases of post-SAH vasospasm. PDGF-β binding to the PDGF receptor-β results in receptor tyrosine kinase domain activation and consequent stimulation of intracellular signaling pathways, including p38 mitogen-activated protein kinase, phosphatidylinositol-3-kinase, Rho-associated protein kinase, and extracellular regulated kinase 1 and 2. Consequent increases in intracellular calcium and increased expression of genes mediating cellular growth and proliferation mediate PDGF-induced augmentation of vascular smooth muscle cell contractility, hypertrophy, and proliferation.

CONCLUSION

Treatments with statins, serine protease inhibitors, and small molecular pathway inhibitors have demonstrated varying degrees of efficacy in prevention of cerebral vasospasm, which is improved with earlier institution.

The effect of subarachnoid erythrocyte lysate on brain injury: a preliminary study

We found that more severe brain injury was caused by subarachnoid erythrocyte lysate, and inflammation associated with Prx2 might be involved in mechanism of brain injury.

Abundant erythrocytes remain and lyse partially in the subarachnoid space after severe subarachnoid haemorrhage (SAH). But the effect of subarachnoid erythrocyte lysate on brain injury is still not completely clear. In this study, autologous erythrocytes (the non-lysate group) and their lysate (the lysate group) were injected separately into the cistern magna of rabbits to induce a model of experimental SAH, although the control group received isotonic sodium chloride solution instead of erythrocyte solution. Results showed that vasospasm of the basilar artery was observed at 72 h after experimental SAH, but there was no significant difference between the non-lysate group and the lysate group. Brain injury was more severe in the lysate group than in the non-lysate group. Meanwhile, the levels of peroxiredoxin 2 (Prx2), IL-6 and TNF-α in brain cortex and in CSF were significantly higher in the lysate group than those in the non-lysate group. These results demonstrated that brain injury was more likely to be caused by erythrocyte lysate than by intact erythrocytes in subarachnoid space, and inflammation response positively correlated with Prx2 expression might be involved in mechanism of brain injury after SAH.

Controversies and evolving new mechanisms in subarachnoid hemorrhage

Despite decades of study, subarachnoid hemorrhage (SAH) continues to be a serious and significant health problem in the United States and worldwide. The mechanisms contributing to brain injury after SAH remain unclear. Traditionally, most in vivo research has heavily emphasized the basic mechanisms of SAH over the pathophysiological or morphological changes of delayed cerebral vasospasm after SAH. Unfortunately, the results of clinical trials based on this premise have mostly been disappointing, implicating some other pathophysiological factors, independent of vasospasm, as contributors to poor clinical outcomes. Delayed cerebral vasospasm is no longer the only culprit. In this review, we summarize recent data from both experimental and clinical studies of SAH and discuss the vast array of physiological dysfunctions following SAH that ultimately lead to cell death. Based on the progress in neurobiological understanding of SAH, the terms "early brain injury" and "delayed brain injury" are used according to the temporal progression of SAH-induced brain injury. Additionally, a new concept of the vasculo-neuronal-glia triad model for SAH study is highlighted and presents the challenges and opportunities of this model for future SAH applications.

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.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

ADMISSION ANGIOGRAPHIC CEREBRAL CIRCULATION TIME MAY PREDICT SUBSEQUENT ANGIOGRAPHIC VASOSPASM AFTER ANEURYSMAL SUBARACHNOID HEMORRHAGE

OBJECTIVE

Angiographic cerebral vasospasm occurs in approximately 70% of patients hospitalized after aneurysmal subarachnoid hemorrhage (SAH) and is associated with poor outcome. In this study, we examined whether or not cerebral circulation time (CCT) measured with digital subtraction angiography was associated with angiographic vasospasm.

METHODS

Patients who underwent cerebral angiography within 24 hours of SAH were analyzed. Contrast dye transit time from the arterial to the venous phase was measured to obtain CCT (supraclinoid internal carotid artery to parietal cortical veins) and microvascular CCT (cortical middle cerebral artery to parietal cortical veins). Patients with ruptured anterior circulation aneurysms and vasospasm on follow-up angiography (Group A) were compared with patients with SAH without vasospasm (Group B) and with normal control subjects (Group C).

RESULTS

There were 20 patients in Group A (mean age, 51 ± 13 yr), 17 patients in Group B (56 ± 12 yr), and 98 patients in Group C (52 ± 12 yr). CCT in patients in Group A (7.7 ± 1.9 s) was significantly longer than those in Groups B (6.6 ± 1.2 s; P = 0.005) and C (5.9 ± 1 s; P &lt; 0.001). Microvascular CCT in patients in Group A (7.1 ± 1.8 s) was significantly longer than those in Groups B (6.1 ± 1.2 s; P = 0.003) and C (5.4 ± 0.9 s; P &lt; 0.001).

CONCLUSION

Prolonged CCT, a measurement of increased small vessel resistance, can be identified within 24 hours after SAH and is associated with subsequent angiographic vasospasm. These results suggest that microcirculation changes may be involved in vasospasm.

NMDA receptor antagonist felbamate reduces behavioral deficits and blood-brain barrier permeability changes after experimental subarachnoid hemorrhage in the rat

Increased levels of glutamate and aspartate have been detected after subarachnoid hemorrhage (SAH) that correlate with neurological status. The NMDA receptor antagonist felbamate (FBM; 2-phenyl-1,3-propanediol dicarbamate) is an anti-epileptic drug that elicits neuroprotective effects in different experimental models of hypoxia-ischemia. The aim of this dose-response study was to evaluate the effect of FBM after experimental SAH in rats on (1) behavioral deficits (employing a battery of assessment tasks days 1-5 post-injury) and (2) blood-brain barrier (BBB) permeability changes (quantifying microvascular alterations according to the extravasation of protein-bound Evans Blue by a spectrophotofluorimetric technique 2 days post-injury). Animals were injected with 400 muL of autologous blood into the cisterna magna. Within 5 min, rats received daily oral administration of FBM (15, 30, or 45 mg/kg) for 2 or 5 days. Results were compared with sham-injured controls treated with oral saline or FBM (15, 30, or 45 mg/kg). FBM administration significantly ameliorated SAH-related changes in Beam Balance scores on days 1 and 2 and Beam Balance time on days 1-3, Beam Walking performance on days 1 and 2, and Body Weight on days 3-5. FBM also decreased BBB permeability changes in frontal, temporal, parietal, occipital, and cerebellar cortices; subcortical and cerebellar gray matter; and brainstem. This study demonstrates that, in terms of behavioral and microvascular effects, FBM is beneficial in a dose-dependent manner after experimental SAH in rats. These results reinforce the concept that NMDA excitotoxicity is involved in the cerebral dysfunction that follows SAH.

Neurokinin-1 receptor antagonism in a rat model of subarachnoid hemorrhage: prevention of upregulation of contractile ETB and 5-HT1B receptors and cerebral blood flow reduction

Object

Cerebral vasospasm following subarachnoid hemorrhage (SAH) leads to reduced cerebral blood flow (CBF) and to cerebral ischemia, in some cases even producing infarction and long-term disability. The goal of the present study was to investigate the hypothesis that inhibition of neurokinin-1 receptors (NK1Rs) by administration of L-822429 blunts the decrease in CBF as well as cerebrovascular receptor upregulation in an animal model of SAH.

Methods

Subarachnoid hemorrhage was induced in rats by injection of 250 μl of blood into the prechiasmatic cistern. The NK1R inhibitor L-822429 was injected intracisternally 30 minutes and 24 hours after the induction of SAH. Two days after SAH induction, the basilar arteries were harvested, and contractile responses to endothelin-1 (ET-1, an ETA- and ETB-receptor agonist) and 5-carboxamidotryptamine (a 5-hydroxytryptamine-1 [5-HT1]-receptor agonist) were investigated using sensitive myographs. To determine whether NK1R inhibition had an influence on local CBF after post-SAH, a quantitative autoradiographic technique was used.

After SAH, the vascular receptor phenotype was changed in cerebral arteries through upregulation of contractile ETB and 5-HT1B receptors, while regional and total CBF were markedly reduced. Treatment with the selective NK1R inhibitor L-822429 prevented both the receptor upregulation and the reduction in regional and global CBF.

Conclusions

The data reveal the coregulation of vascular receptor changes and blood flow effects, and also show that interaction with a small-molecule NK1R antagonist is a promising area of focus for the development of specific treatments for SAH.

Acute cerebral vascular injury after subarachnoid hemorrhage and its prevention by administration of a nitric oxide donor

Object

Structural changes in brain parenchymal vessels occur within minutes after subarachnoid hemorrhage (SAH). These changes include platelet aggregation, activation of vascular collagenases, and destruction of perivascular collagen IV. Because collagen IV is an important component of the basal lamina, the authors attempted to further define changes in vascular structure (length and luminal diameter) and their relationship to vascular permeability immediately after SAH. In addition, the authors explored whether such alterations were attenuated by administration of a nitric oxide (NO) donor.

Methods

Endovascular perforation was used to induce SAH in rats. Two sets of experiments were performed. The first established changes in vascular structure and permeability (collagen IV and endothelial barrier antigen [EBA] dual immunofluorescence) during the first 24 hours after SAH. In the second, the investigators examined the effects of an NO donor on vascular structure, permeability, and collagenase activity (in situ zymography). In this second study, animals received intravenous infusion of the NO donor S-nitrosoglutathione (GSNO, 1 μM/8 μl/min) 15 minutes after induction of SAH and were killed 3 hours after SAH onset. Controls were naive unoperated animals for the first study and saline-infused SAH animals for the second.

The authors found a time-dependent decrease in area fraction, length, and luminal diameter of collagen IV– and EBA-immunofluorescent vessels after SAH. The greatest change occurred at 3 hours after onset of SAH. Administration of GSNO was associated with striking preservation of collagen IV and EBA immunofluorescence compared with saline treatment. Zymography indicated decreased collagenase activity in GSNO-treated SAH animals compared with saline-treated SAH animals.

Conclusions

These results demonstrate changes in the structure and permeability of brain parenchymal microvessels after SAH and their reversal by treatment with an NO donor.

Effect of combined simvastatin and cyclosporine compared with simvastatin alone on cerebral vasospasm after subarachnoid hemorrhage in a canine model

Object

The object of this study was to determine whether the combination of cyclosporine and simvastatin could ameliorate cerebral vasospasm after subarachnoid hemorrhage (SAH) in a canine model to a greater extent than simvastatin alone.

Methods

Animals were assigned to one of three groups: control (five dogs), simvastatin alone (four), or simvastatin and cyclosporine (four). A double SAH model was used. Baseline basilar artery (BA) angiograms were obtained. These were repeated at Days 3, 7, and 10. Measurement of the BA diameter was performed.

Decreased BA diameter was seen on Day 3 in the control and simvastatin/cyclosporine group. A return to baseline diameters was seen by Day 7. An increase from baseline diameter was seen in the simvastatin group at Day 10.

Conclusions

Cyclosporine may interfere with the vasodilatory effects of simvastatin. Vasodilation greater than baseline is seen at Day 10 in the simvastatin group. The combination of simvastatin and cyclosporine does not ameliorate cerebral vasospasm in a canine model to a greater extent than simvastatin alone.

ERK1/2 inhibition attenuates cerebral blood flow reduction and abolishes ET(B) and 5-HT(1B) receptor upregulation after subarachnoid hemorrhage in rat

Upregulation of endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors via transcription has been found after experimental subarachnoid hemorrhage (SAH), and this is associated with enhanced phosphorylation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK1/2). In the present study, we hypothesized that inhibition of ERK1/2 alters the ET(B) and 5-HT(1B) receptor upregulation and at the same time prevents the sustained cerebral blood flow (CBF) reduction associated with SAH. The ERK1/2 inhibitor SB386023-b was injected intracisternally in conjunction with and after the induced SAH in rats. At 2 days after the SAH, cerebral arteries were harvested for quantitative real-time polymerase chain reaction, immunohistochemistry and analysis of contractile responses to endothelin-1 (ET-1; ET(A) and ET(B) receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) in a sensitive myograph. To investigate if ERK1/2 inhibition had an influence on the local and global CBF after SAH, an autoradiographic technique was used. At 48 h after induced SAH, global and regional CBF were reduced by 50%. This reduction was prevented by treatment with SB386023-b. The ERK1/2 inhibition also decreased the maximum contraction elicited by application of ET-1 and 5-CT in cerebral arteries compared with SAH. In parallel, ERK1/2 inhibition downregulated ET(B) and 5-HT(1B) receptor messenger ribonucleic acid and protein levels compared with the SAH. Cerebral ischemia after SAH involves vasoconstriction and subsequent reduction in the CBF. The results suggest that ERK1/2 inhibition might be a potential treatment for the prevention of cerebral vasospasm and ischemia associated with SAH.

Signaling mechanisms in cerebral vasospasm

The elusive nature of events that sustain cerebral vasospasm after subarachnoid hemorrhage resulting from a ruptured aneurysm presents major challenges in designing effective therapies for this frequently devastating condition. Protracted cerebral artery constriction entails several dynamic components in intracellular signaling events initiated by endothelial factors, products of hemolysate, and numerous kinases, as well as increased intracellular Ca(2+). The rationale for potential treatment modalities and their efficacy are discussed in this brief review.

Delayed Intracranial Delivery of a Nitric Oxide Donor from a Controlled-release Polymer Prevents Experimental Cerebral Vasospasm in Rabbits

OBJECTIVE

Decreased local availability of nitric oxide (NO) may mediate chronic vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Previous reports have shown that early treatment with NO prevents vasospasm in animals. We evaluated the efficacy of controlled-release polymers that contain the NO donor diethylenetriamine (DETA-NO) for the delayed treatment of vasospasm in a rabbit model of SAH.

METHODS

DETA-NO 20% (wt/wt) was incorporated into ethylene-vinyl acetate (EVAc) polymers. Animals (n = 52) were randomized to two experimental groups. In the first group (n = 32), animals received SAH and implantation of either 20% DETA-NO/EVAc polymer at a dose of 0.5 mg/kg of DETA-NO (n = 16) or empty EVAc polymer (n = 16). Polymers were implanted 24 (n = 16) or 48 hours (n = 16) after SAH. In the second group (n = 20), animals received SAH and implantation of either 20% DETA-NO/EVAc polymer at a dose of 1.3 mg/kg (n = 10) or empty EVAc (n = 10). Polymers were implanted 24 (n = 10) or 48 hours (n = 10) after SAH. An additional group (n = 16) underwent either sham operation (n = 6) or SAH only (n = 10). Animals were killed 3 days after hemorrhage, and the basilar arteries were processed for morphometric measurements. Results were analyzed using Student's t test.

RESULTS

Treatment with 20% DETA-NO/EVAc polymers at a dose of 1.3 mg/kg significantly increased basilar artery lumen patency when administered at 24 (97 +/- 6% versus 73 +/- 10%; P = 0.0396) or 48 hours (94 +/- 6% versus 71 +/- 9%; P = 0.03) after SAH. Treatment with 20% DETA-NO/EVAc polymers at a dose of 0.5 mg/kg administered 48 hours after SAH significantly increased lumen patency (82 +/- 8% versus 68 +/- 12%; P = 0.03); a dose of 0.5 mg/kg, 24 hours after SAH, did not reach statistical significance (74 +/- 7% versus 65 +/- 9%; P = 0.16). The SAH-only group had a lumen patency of 67 +/- 12%.

CONCLUSION

Delayed treatment of SAH with controlled-release DETA-NO polymers prevented experimental posthemorrhagic vasospasm in the rabbit. This inhibition was dose-dependent. This further confirms the role of NO in the pathogenesis of vasospasm.

Acute alterations in microvascular basal lamina after subarachnoid hemorrhage

Object. Aneurysmal subarachnoid hemorrhage (SAH) causes acute and delayed ischemic brain injuries. The mechanisms of acute ischemic injury following SAH are poorly understood, although an acute increase in microvascular permeability has been noted. The integrity of cerebral microvessels is maintained in part by components of basal lamina: collagen IV, elastin, lamina, and so forth. Destruction of basal lamina components by collagenases and matrix metalloproteinases (MMPs), especially MMP-9, has been known to occur in other ischemic models. The authors assessed the integrity of cerebral microvasculature after acute SAH by examining collagen IV and MMP-9 levels and collagenase activity in the microvessels.

Methods. Subarachnoid hemorrhage was induced in rats through endovascular perforation of the intracranial bifurcation of the internal carotid artery. Animals were killed 10 minutes to 48 hours after SAH or sham operation (time-matched controls). Levels of collagen IV and MMP-9 were studied in the microvasculature by performing immunoperoxidase and immunofluorescence staining, and collagenase activity was assessed by in situ zymography.

Little change occurred in collagen IV and MMP-9 immunostaining or collagenase activity at 10 minutes or 1 hour after SAH. Starting 3 hours after SAH, collagen IV immunostaining was reduced or eliminated along segments of microvessels whereas MMP-9 staining was segmentally increased. These effects reached a maximum at 6 hours and returned toward those values in sham-operated controls at 48 hours.

Conclusions. Results of this study demonstrated an acute loss of collagen IV from the cerebral microvasculature after SAH and indicated that MMP-9 contributes to this event. The loss of collagen IV might contribute to the known failure of the blood—brain barrier after SAH.

Oxyhemoglobin produces necrosis, not apoptosis, in astrocytes

OBJECTIVE

Subarachnoid blood, resulting from traumatic brain injury or subarachnoid hemorrhage, has been linked with cell injury and stress gene induction. We investigated whether oxyhemoglobin (OxyHb), a major component in blood clots, exerts a cytotoxic effect on cultured astrocyte cells, and the pattern of cell death.

METHODS

A murine astrocyte cell line was used (passages 28-35). Cell growth studies were performed 24, 48, and 72 h after exposure to OxyHb (1, 10, and 30 microM). Western blot analysis of poly adenosine diphosphate [ADP]-ribose polymerase (PARP) cleavage and TUNEL stain analysis were performed to determine the presence of apoptosis. Cells treated with OxyHb were also evaluated with transmission electron microscopy to determine changes that may have occurred at the ultra-structural level.

RESULTS

OxyHb (10-30 microM), after 72-h incubation, inhibited cell growth. Western blot analysis of PARP and TUNEL staining for the presence of apoptosis were essentially negative in all groups. Ultrastructural analysis revealed an abundance of necrosis and random occurrences of apoptosis in a few cells.

CONCLUSION

Cultured astrocytes exposed to OxyHb causing cell growth inhibition could possibly be a result of cellular cytotoxicity and necrosis.

Oxidative degradation of bilirubin produces vasoactive compounds

Subarachnoid haemorrhage is often followed by haemolysis and concomitant oxidative stress, and is frequently complicated by pathological vasoconstriction or cerebral vasospasm. It is known that upregulation of haem oxygenase (HO-1) is induced by oxidative stress and results in release of biliverdin and bilirubin (BR), which are scavengers of reactive oxygen species (ROS). Here we report biomimetic studies aimed at modelling pathological conditions leading to oxidative degradation of BR. Oxidative degradation products of BR, formed by reaction with hydrogen peroxide (an ROS model system), demonstrated biological activity by stimulating oxygen consumption and force development in vascular smooth muscle from porcine carotid artery. Analogous biological activity was observed with vasoactive cerebrospinal fluid from subarachnoid haemorrhage patients. Three degradation products of BR were isolated: two were assigned as isomeric monopyrrole (C9H11N2O2) derivatives, 4-methyl-5-oxo-3-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and 3-methyl-5-oxo-4-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and the third was 4-methyl-3-vinylmaleimide (MVM), a previously isolated photodegradation product of biliverdin. Possible mechanisms of oxidative degradation of BR are discussed. Tentative assignment of these structures in the cerebrospinal fluid (CSF) of cerebral vasospasm patients has been made. It is proposed that one or more of the degradation products of biliverdin or bilirubin are involved in complications such as vasospasm and or pathological vasoconstriction associated with haemorrhage.

Hemolysate induces tyrosine phosphorylation and collagen-lattice compaction in cultured fibroblasts

Hemolysate, a proposed causative agent for cerebral vasospasm after subarachnoid hemorrhage, produces contraction of cerebral arteries by activation of tyrosine kinases. In addition, hemolysate increases fibroblast-collagen compaction that could play a role in cerebral vasospasm. We studied the effect of hemolysate on tyrosine phosphorylation and fibroblast-collagen compaction in cultured canine basilar and human dermal fibroblasts using tyrosine kinase inhibitors and tyrosine antibodies. Hemolysate enhanced tyrosine phosphorylation of two proteins, 64 and 120 kDa, in cultured canine basilar artery and human dermal fibroblast cells. The effect of hemolysate was time-dependent and concentration-dependent. Oxyhemoglobin and ATP, the two major components of hemolysate, produced similar tyrosine phosphorylation, however, with a different time course. Tyrosine kinase inhibitors genistein and tyrphostin A51 abolished the effect of hemolysate in both cerebral and dermal fibroblasts. Hemolysate increased fibroblast-populated collagen-lattice compaction and tyrosine kinase inhibitors genistein and tyrphostin A51 attenuated the effect of hemolysate. We conclude that hemolysate activates tyrosine kinase that leads to the increase of fibroblast compaction. This effect of hemolysate may contribute to cerebral vasospasm.

Anti-oxidants prevent focal rat brain injury as assessed by induction of heat shock proteins (HSP70, HO-1/HSP32, HSP47) following subarachnoid injections of lysed blood

The initial aim of this study was to determine if the HSP70 (the main inducible heat shock protein), HO-1 (heme oxygenase-1, HSP32) and HSP47 (a collagen chaperone) stress proteins were induced in the same focal regions of rat brain following experimental subarachnoid hemorrhage (SAH). The next objective was to determine whether anti-oxidants prevented the stress gene expression in the focal regions. Lysed blood (150 microliter) was injected into the subarachnoid space of adult, female Sprague-Dawley rats via the cisterna magna. Animals were sacrificed 24 h later. Immunocytochemistry showed focal regions of stress gene induction in most animals (13/21), HSP70 and HO-1 proteins being expressed in neurons, microglia and astrocytes and HSP47 being expressed in microglia. Co-induction of the same three stress proteins was observed in focal areas in the striatum and cerebellum as well. In the 13 animals with focal regions of stress gene induction there were 8.1+/-1.8 foci in cortex, 5.5+/-0.9 foci in striatum, and 11.7+/-7.3 foci in cerebellum in the brain of each animal. The focal regions of stress gene induction varied in size from 200 micrometer to 7 mm in diameter. Systemic administration of the tirilazad-like anti-oxidants U101033E (n=8) and U74389G (n=7) completely blocked stress protein induction in focal brain regions normally produced by cisternal injections of lysed blood. There were fewer drug treated animals (0/15) with focal areas of stress gene induction compared to non-drug (13/21) treated animals following the cisternal lysed blood injections (p<0.01 using Fisher's probability test). This study shows that anti-oxidants prevent focal regions of injury as assessed by heat shock protein expression in a rat model of SAH.

Antivasospastic and brain-protective effects of a hydroxyl radical scavenger (AVS) after experimental subarachnoid hemorrhage

OBJECT

The radical scavenger (+/-)-N,N'-propylenedinicotinamide (AVS) was shown recently to ameliorate delayed neurological deficits resulting from ischemia in patients who have had an aneurysmal subarachnoid hemorrhage (SAH). The aim of this study was to evaluate the effect of AVS administration after experimental SAH on 1) behavioral deficits; 2) angiographically confirmed basilar artery (BA) spasm; and 3) blood-brain barrier (BBB) permeability changes.

METHODS

These parameters were measured by 1) using a battery of well-characterized chronic assessment tasks over a 5-day observation period; 2) assessing in vivo the mean vessel diameter 2 days after SAH; and 3) evaluating the extravasation of protein-bound Evans Blue dye by using a spectrophotofluorimetric technique 2 days after SAH. Groups of eight to 10 rats received injections of 400 microl of autologous blood into the cisterna magna. Within 5 minutes after the surgical procedures were completed the rats were treated with an intravenously administered continuous infusion of saline (Group III) or AVS (1 mg/kg/minutes, Group IV). Results were compared with those in sham-operated animals treated with intravenously administered saline (Group I) or AVS (Group II). The AVS-treated rats had significantly improved balance beam scores on Days 1 to 2 (p < 0.05), shorter beam traverse times on Day 1 (p < 0.05), and better beam walking performance on Days 1 to 4 (p < 0.01), but no significant effect was seen in terms of SAH-related changes in body weight. Treatment with AVS also attenuated the SAH-induced BA spasm (p < 0.05) and decreased BBB permeability changes in frontal, temporal, parietal, occipital, and cerebellar cortices, and in the subcortical and cerebellar gray matter and brainstem (p < 0.01).

CONCLUSIONS

These results demonstrate useful antivasospastic and brain-protective actions of AVS after induction of experimental SAH and provide support for observations of beneficial effects of AVS made in the clinical setting.

Raffinee, a free radical scavenger, in the treatment of subacute stage brain and spinal cord lesions: a case report

This report presents the effects of the natural antioxidant formulation "Raffinee" in treatment of a case with subacute cerebellar hemorrhage and a case with subacute incomplete cervical cord injury. Four days after onset of cerebellar hemorrhage, the regimen started and ameliorated severe headache and dizziness within 3 days. Forty-five days after incomplete spinal cord injury with marked edema of cervical cord, the regimen started. Excellent motor and sensory function recovery were obtained within one month with remission of cord edema. The dosage of "Raffinee" is equivalent to 2,280,000 units of superoxide radical scavenging activity and 47,000 units of hydroxyl radical scavenging activity. Based on the secondary injury theory, superoxide and hydroxyl radical scavengers may have a valuable use in subacute central nervous system (CNS) lesions. Further larger scale of randomized, placebo-controlled, double-blind clinical trials are indicated to verify the effect of "Raffinee" on subacute CNS lesions.

Augmentation of both hemolysate-induced contraction and activation of protein kinase C by submaximum activation in canine cerebral arteries in vitro

Although phorbol esters, synthetic activators of protein kinase C (PKC), can stimulate large increases in the binding of cytosolic PKC to form membrane-bound PKC (PKCm, an indicator of PKC activation), the authors report that even small increases in PKCm induced by phorbol esters (8-12% of total PKC content) can be associated with significant PKC-mediated contractions in vitro (50-85% of maximum) in normal canine cerebral arteries. Increases in PKCm of similarly small magnitude were found in vitro when control artery segments were exposed to hemolysate, but only if the arterial smooth-muscle cells were first slightly depolarized by increased extracellular potassium to values of membrane potential similar to those observed in canine cerebral arteries during chronic cerebral vasospasm. These increases in PKCm (6-8% of total PKC content) coincided with a greatly augmented contractile response to hemolysate. These results show that the previous observation of only a small increase in PKCm (approximately 7% of total PKC content) after experimental subarachnoid hemorrhage in the canine model does not preclude a potentially important role for PKC-mediated contraction in the pathogenesis of cerebral vasospasm.

The complement membrane attack complex and the bystander effect in cerebral vasospasm

Activation of complement results in formation of membrane attack complexes (MACs) that can insert themselves either into cells that initiate complement activation or into nearby (“innocent bystander”) cells. The MACs form large-conductance, nonspecific ion channels that can cause lytic or sublytic cell damage. The authors used a highly sensitive patch clamp technique to assess the contribution of the bystander effect to the pathophysiology of cerebral vasospasm. They compared the effect of complement activation by autologous aged versus fresh erythrocytes on the membrane conductance of freshly isolated rat cerebral artery smooth-muscle cells. In the presence of autologous serum, aged, but not fresh, erythrocytes caused a large increase in membrane conductance, an effect that was prevented by heat-inactivating the serum. Ethyleneglycol tetraacetic acid in the presence of Mg++ attenuated the effect, indicating that complement activation was taking place via the classic pathway. The effect was reproduced by zymosan-activated autologous serum, suggesting that such changes in conductance could result from insertion of MACs secondary to a bystander effect. Both C8- and C9-depleted heterologous sera produced minimal effects that were converted to full effect by addition of the missing complement component. Superoxide dismutase plus catalase did not attenuate the conductance changes produced by autologous serum plus aged erythrocytes. Autologous serum plus aged erythrocyte membrane ghosts that were free of lysate caused a typical increase in conductance. This study demonstrates that complement activation by aged erythrocytes can result in MAC insertion into innocent bystander smooth-muscle cell membranes and that this mechanism, heretofore undescribed, may contribute to development of vasospasm after subarachnoid hemorrhage.

Coagulative and fibrinolytic activation in cerebrospinal fluid and plasma after subarachnoid hemorrhage

OBJECTIVE

Intrathecal fibrinolytic therapy has been used as one of the anticerebral vasospasm (VS) preventative therapies in patients with subarachnoid hemorrhage (SAH). However, the changes in coagulation and fibrinolysis in the blood and cerebrospinal fluid (CSF) after SAH remain unknown.

METHODS

Fifty patients with SAH caused by ruptured cerebral aneurysms were studied postoperatively to detect the serial changes of the thrombin-antithrombin III complex, active plasminogen activator inhibitor (PAI)-1, and tissue plasminogen activator (tPA)-PAI complex (tPA-PAI) activities in the plasma and CSF collected from cisternal drainage catheters.

RESULTS

The CSF levels of all parameters and plasma PAI-1 levels were significantly higher in patients with severe SAH than in those with mild SAH. There was no relationship between the CSF and plasma levels of these parameters (except the CSF levels of tPA-PAI) and the initial neurological statuses. The CSF PAI-1 levels increased to greater than 20 ng/ml near the time of the occurrence of cerebral VS, whereas they remained below 20 ng/ml in patients without VS. The CSF tPA-PAI levels showed the highest peak near the time of VS remission. The CSF PAI-1 and tPA-PAI levels were significantly lower in patients with good outcomes than in those with poor outcomes.

CONCLUSION

Both the coagulative and fibrinolytic systems were activated in the CSF and plasma after SAH in correlating to the amount of SAH clot. The intrathecal administration of fibrinolytic agents should be started early after surgery, before CSF PAI-1 levels increase, for patients with severe SAH. Patients with CSF PAI-1 levels greater than 20 ng/ml experienced high incidence of VS and poor outcomes.

Three-dimensional analysis of vasospastic major cerebral arteries in rats with the corrosion cast technique

BACKGROUND AND PURPOSE

Although mice, rats, and other small animals are commonly used for molecular biology research, their use in the evaluation of cerebral vasospasm after subarachnoid hemorrhage is somewhat problematic because of the correspondingly small size of their cerebral vessels. We have already reported that the corrosion cast technique was useful for evaluating newly formed cerebral vessels in neural grafts in these small animals. In the present study we applied the corrosion cast technique to the evaluation of hemolysate-induced cerebral vasospasm in rats and performed three-dimensional analysis for comparison. The casting was done 10 minutes after the hemolysate injection, so that only acute "vasospasm" was assessed.

METHODS

After withdrawal of 0.1 mL cerebrospinal fluid, 0.2 mL hemolysate (n = 9) or saline (n = 10) was injected into the cisterna magna of male Sprague-Dawley rats weighing between 300 and 350 g. Ten minutes later, perfusion of a semipolymerized casting medium was performed at an injection pressure of 100 to 120 mm Hg. The brains were immersed and corroded in 10% NaOH solution. After these procedures, the basilar artery as well as peripheral vessels was analyzed morphologically with scanning electron microscopy. Conventional histological analysis with the use of paraffin-embedded section with hematoxylin-eosin staining was also performed, and the results were compared with those for the corrosion cast methods.

RESULTS

In the saline-injected group, SEM showed that the inner surface of the basilar artery was smooth and the form of the endothelial cell was printed on the surface of the cast. In the hemolysate-injected group, the basilar artery showed an apparent vasospasm over its entire length, and corrugation was observed on the inner surface of the basilar artery in a three-dimensional fashion. Higher magnification revealed that the nuclei of the endothelial cells were distorted. Local narrowing of the basilar artery and vasospasm in the arteries of the anterior circulation and in peripheral arteries were also observed. Measurement of the inner diameter of the basilar artery showed 37.8% contraction in the hemolysate-injected group compared with the saline-injected group by the corrosion cast method. This degree of vasospasm was similar to that observed by the conventional histological method.

CONCLUSIONS

In this report we show that detailed three-dimensional observation in the rat can be performed qualitatively and quantitatively with the corrosion cast technique. We conclude that this method derives an accurate measurement of the diameter of rat major cerebral arteries and is more reliable for analyzing vasospasm in rats than angiography and other conventional procedures.

The complement membrane attack complex and the bystander effect in cerebral vasospasm

Activation of complement results in formation of membrane attack complexes (MACs) that can insert themselves either into cells that initiate complement activation or into nearby ("innocent bystander") cells. The MACs form large-conductance, nonspecific ion channels that can cause lytic or sublytic cell damage. The authors used a highly sensitive patch clamp technique to assess the contribution of the bystander effect to the pathophysiology of cerebral vasospasm. They compared the effect of complement activation by autologous aged versus fresh erythrocytes on the membrane conductance of freshly isolated rat cerebral artery smooth-muscle cells. In the presence of autologous serum aged, but not fresh, erythrocytes caused a large increase in membrane conductance, an effect that was prevented by heat-inactivating the serum. Ethyleneglycol tetraacetic acid in the presence of Mg++ attenuated the effect, indicating that complement activation was taking place via the classic pathway. The effect was reproduced by zymosan-activated autologous serum, suggesting that such changes in conductance could result from insertion of MACs secondary to a bystander effect. Both C8- and C9-depleted heterologous sera produced minimal effects that were converted to full effect by addition of the missing complement component. Superoxide dismutase plus catalase did not attenuate the conductance changes produced by autologous serum plus aged erythrocytes. Autologous serum plus aged erythrocyte membrane ghosts that were free of lysate caused a typical increase in conductance. This study demonstrates that complement activation by aged erythrocytes can result in MAC insertion into innocent bystander smooth-muscle cell membranes and that this mechanism, heretofore undescribed, may contribute to development of vasospasm after subarachnoid hemorrhage.

Cisternal talc injection in dog can induce delayed and prolonged arterial constriction resembling cerebral vasospasm morphologically and pharmacologically

BACKGROUND

The possible role of inflammation in the pathogenesis of cerebral vasospasm has been noted in recent studies. In order to examine the role of inflammation, we examined the vasocontractile activity of talc, which is known to cause severe inflammation, using a canine cisternal talc injection model.

METHODS

Under general anesthesia, a sterile talc powder suspended in saline was injected into the cisterna magna of the dog. Serial vertebral angiography and postmortem histologic changes of the harvested basilar artery were examined. The morphologic and pharmacologic features of talc-induced vessel spasm were compared with the usual autologous blood-induced artery spasm.

RESULTS

Cisternal injection of sterile talc powder caused no early spasm, but induced definite basilar arterial constriction 2 days after injection. This vascular constriction was observed to continue up to 7 days after injection. Ultrastructural study of the constricted vessel revealed several morphologic changes, such as corrugation of the elastic lamina, subintimal proliferation, migration of smooth muscle cells, detachment of endothelial cells, etc.; findings that are compatible with the changes observed in vasospasm. Pharmacologic study showed a moderate decrease in the maximal contraction to KCl and UTP. Endothelium-dependent relaxation was markedly disturbed, while endothelium-independent relaxation was preserved. These pharmacologic properties were also similar to those reported in vasospasm.

CONCLUSIONS

Our present study indicates that the several changes of vascular properties, which had been considered to be specific to cerebral vasospasm, can be regarded as a nonspecific biologic defense reaction against the foreign body. The analysis of the common pathway from talc and autologous blood to vasospasm may lead to the pathogenesis of cerebral vasospasm.

Effects of a hydroxyl radical scavenger on delayed ischemic neurological deficits following aneurysmal subarachnoid hemorrhage: results of a multicenter, placebo-controlled double-blind trial

A water-soluble, novel synthetic compound, AVS ((+/-)-N, N'-propylenedinicotinamide; nicaraven) has no demonstrable vasoactive properties but scavenges hydroxyl radicals in aqueous environmental conditions at neutral pH. Based on the results of preceding experimental and clinical studies showing marked ameliorative effects of AVS on cerebral vasospasm and ischemic brain damage, a multicenter, placebo-controlled double-blind clinical trial was undertaken to verify its beneficial effects on delayed ischemic neurological deficits (DINDs) due to vasospasm and on the overall outcome of patients with subarachnoid hemorrhage (SAH). A total of 162 patients with SAH who had Glasgow Coma Scale scores between 7 and 15 on admission were enrolled in the trial. Drug administration (4 g AVS or 4 g glucose as placebo; infused intravenously for 6-8 hours once a day) was begun within 5 days post-SAH and continued for 10 to 14 days. Intent-to-treat analysis of these patients revealed that the overall incidence of DINDs, which was defined as an exacerbation of impaired consciousness and/or focal neurological deficits, was significantly reduced, by 34.5% (placebo 54.2%, AVS 35.5%; p < 0.05, Mann-Whitney U-test). The Glasgow Outcome Scale (GOS) score at 1 month was significantly improved by AVS (p < 0.05, U-test). At 3 months, the difference in the GOS scores between the groups became marginal on U-tests (p < 0.10), but the percentage of good outcome tended to increase, with a relative increase of 20.3% (AVS 76.3%, placebo 63.4%; p < 0.10, chi-square test), and the cumulative incidence of death was significantly reduced (p < 0.05, log-rank test). No significant adverse reaction attributable to treatment was observed. the usefulness of AVS in therapy for SAH is strongly indicated by the fact that the agent significantly ameliorated DINDs, leading to a marked improvement in the GOS scores at 1 month, as well as a reduction in the cumulative incidence of death by 3 months.

[Pharmacological therapeutic prospects of cerebral vasospasm]

New therapies of cerebral vasospasm aim to prevent the effects of subarachnoid haemorrhage. These effects result in red blood cell haemolysis and release of oxyhaemoglobin, free radicals formation and lipid peroxidations, imbalance in endothelial modulation of vasomotor tone and activation of the complement system. Low doses of fibrinolytic agents administered intrathecally accelerate the fibrinolysis of the clot and reduce the oxyhaemoglobin release. The tissue-type plasminogen activator has proven to be effective in preventing vasospasm, but the modalities of this therapy remain to be defined. Free radical reactions may be inhibited by free radical scavengers and inhibitors of lipid peroxidations. Tirilazad is a potent inhibitor of lipid peroxidations, which improves the patients' outcome and has gone to Phase III human trials. Superoxide dismutase and tropolone derivatives are currently evaluated in animal models. Vasomotor tone can be modified in experimental models either by blocking endothelin receptors (BQ-123), or by facilitating the release and enhancing the effect of nitric oxide using protein kinase C inhibitors, drugs that increase intracellular calcium (cyclopiazonic acid, LP-805) and free radicals scavengers (superoxide dismutase). These possibilities are being investigated. Finally, preliminary studies have demonstrated the efficacy of FUT-175, an inhibitor of the complement system, in the prevention of vasospasm. In the next years, these new therapies have to be validated by prospective and randomized clinical trials to propose guidelines for the management of patients at risk of cerebral vasospasm after aneurysmal rupture.

Effect of vasoconstrictor agents on diacylglycerol content of normal and vasospastic canine basilar arteries in vitro

A causal or supportive relationship between 1,2-diacylglycerol (DAG) content and the maintenance of tonic vasoconstriction was sought in canine basilar arteries treated in vitro with various agents reported to increase DAG levels in other tissues (platelet-derived growth factor, vasopressin, angiotensin II, and endothelin-1) and, conversely, with agents known to activate sustained constriction (high K+, phorbol ester, hemolysate, and endothelin-1). Multiple segments from individual isolated arteries were prepared. Some segments were immediately frozen as controls and others incubated in physiological saline solution at 37 degrees C for either 5 minutes or 30 minutes in the presence or absence of different concentrations of the test materials. Segments were then quickly frozen until homogenized for lipid extraction and DAG assay. The DAG content of samples incubated up to 2 hours in physiological saline solution alone did not significantly differ from that of immediately frozen control samples. Resting DAG content expressed relative to total protein measured in each sample averaged 3.82 +/- 0.26 (standard error of the mean) pmol DAG/microgram of protein (74 samples from 37 arteries). Endothelin at 2 x 10(-7) mol/L led to a statistically significant increase in DAG content of approximately 40% of basal content at 5 and 30 minutes. A smaller increase in DAG attributable to hemolysate (approximately 25%) was statistically significant at 30 minutes, whereas vasopressin provoked a notable decrease in DAG content. The other agents had no effect. No differences in these results were noted between normal canine basilar arteries and arteries constricted in vivo by subarachnoid blood clot before isolation.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the formation of endothelin by lysed red blood cells from endogenous precursor

The release of endothelin from various blood cell fractions was investigated. Human as well as rat blood cell fractions homogenized by sonification were incubated in buffer for up to 60 min. Neither in platelet nor leukocyte homogenates from either species could immunoreactive endothelin be detected. In contrast, homogenates of red blood cells from both species showed a rapid and time-dependent rise of immunoreactive endothelin levels, reaching a peak at 15 min and decreasing thereafter. However, at time point 0 no immunoreactive endothelin could be detected. Reverse phase high performance liquid chromatography showed immunoreactive endothelin to consist of endothelin-1 as well as big endothelin-1. The release of immunoreactive endothelin in human and rat homogenates was concentration-dependently inhibited by the protease inhibitors, leupeptin, phosphoramidon, chymostatin and pepstatin A in order of increasing potency. Intact red blood cells did not incorporate [125I]endothelin-1 nor did they transform exogenous big endothelin-1 to endothelin-1. However, haemolysis of red blood cells with hypotonic saline (0.2%) or incubation with pore-forming staphylococcal alpha-toxin induced the release of immunoreactive endothelin into the buffer samples. Thus, apart from the indirect vasoconstrictor, haemoglobin, red blood cells can also liberate the direct vasoconstrictor, endothelin, a finding expected to be of considerable pathophysiological significance.

Neurologic evaluation in a canine model of single and double subarachnoid hemorrhage

The pathophysiology of cerebral vasospasm is complex and multifactorial. The present study sought to identify the degree of correlation between cerebral vasospasm as observed angiographically and clinical evaluation of an animal's neurologic status in the canine model following a single and double experimental subarachnoid hemorrhage (SAH) protocol. Nineteen mongrel dogs underwent single or double experimental SAH by percutaneous needle puncture of the cisterna magna and placement of a subarachnoid blood clot in the basal cistern on day 1 and day 4, respectively. At 72 h after each experimental SAH, vertebral angiography was performed and compared to control angiography. Basilar artery diameter measured at multiple positions was expressed as percentage of control diameter. Clinical evaluation of the animals was performed every day throughout the experiments. To assess the degree of neurologic impairment we developed a coma scale that efficiently estimated motor ability, eye response and eating habits of the animals. Vasoconstriction after experimental SAH reduced mean basilar artery diameter to 79.1% (+/- 5.4) of control diameter following single SAH and to 69.0% (+/- 2.1) of control diameter following double SAH. No changes were observed in the neurologic behavior of the animals throughout the experiment. Since a principal characteristic of human cerebral vasospasm is the close correlation between arterial constriction and neurological deficit, we believe that the canine model of SAH, although good in creating cerebral arterial vasoconstriction, does not fully represent the best model of human cerebral vasospasm.

The kinetics of lymphocyte subsets and macrophages in subarachnoid space after subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

Although it has been suggested that humoral immunity plays a role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage, there has been no quantitative assay for cellular immunity. We studied the kinetics of immune cells in the subarachnoid space after subarachnoid hemorrhage in the rat.

METHODS

One hundred fourteen Sprague-Dawley rats were used in this study. The animals were divided into two groups and injected with either autologous blood (0.3 mL) or saline into the major cistern. They were killed at the specified time: 10 minutes or 1, 2, 3, 5, or 7 days after subarachnoid hemorrhage. For immunohistochemical analysis, the rats' whole brains were frozen, and cryostat sections were prepared. For flow cytometric analysis of immune cell presence, their whole brains underwent enzymatic digestion.

RESULTS

Histopathologic study revealed pathological change of the arterial wall, and immunohistochemical study revealed the existence of macrophages and T cells in the subarachnoid space in animals with a survival time of 2 to 5 days after subarachnoid hemorrhage. A flow cytometric study revealed the peak of appearance of T cells and macrophages 2 days after subarachnoid hemorrhage. The helper-suppressor T cell ratio also reached a peak 2 days after subarachnoid hemorrhage.

CONCLUSIONS

A serial response of immunoreactive cells, which resembles that of the chronic allergic reaction observed in autoimmune diseases or delayed-type hypersensitivity, exists in the subarachnoid space after subarachnoid hemorrhage. The present results suggest that the initial response in cellular immunity, which is followed by humoral immunity and eicosanoid reactions, plays a role in eliciting the development of cerebral vasospasm.

Therapeutic effect of a new immunosuppressant, FK-506, on vasospasm after subarachnoid hemorrhage

We hypothesized that the immunological reaction against extravasated blood might play a role in the development of vasospasm after subarachnoid hemorrhage. Under the hypothesis, we had reported significant therapeutic efficacy of cyclosporin A on vasospasm in canine models. We here investigated the efficacy of a new, potent immunosuppressant, FK-506, on vasospasm in animal models. Dogs were randomly classified into sham operated, subarachnoid hemorrhage treated-1 group, (FK-506, 0.3 mg/kg-d, intramuscular injection), and treated-2 group (FK-506, 0.15 mg/kg-d, intramuscular injection). Levels of the third factor of complement (C3) and the activity of serum complement inducing 50% hemolysis of sheep erythrocytes (CH50) in serum were also determined. In the treated groups, the levels of FK-506 in serum were monitored. As for C3 and CH50, there were no statistically significant differences among the groups and there were no changes between Day 1 and Day 7 in any group. Angiographical diameters of a basilar artery on Days 1 and 7 were measured with a computed image analyzer, and the extent of vasospasm was compared among the groups. Statistically significant differences between the sham-operated group and the other three groups were noted. However, under sufficient levels of FK-506 in serum, the extent of vasospasm in either treated group was the same as that in the subarachnoid hemorrhage group. These results indicate a significant discrepancy in the therapeutic mechanism for vasospasm between cyclosporin A and FK-506. They have common aspects in the immunosuppressive mechanism. However, in T-cell suppression, the different mechanism in situ between the two drugs is also postulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental basilar artery spasm caused by autologous blood application: effects of clot removal and topical nicardipine

In 24 albino New-Zealand rabbits spasm of the basilar artery was produced by local application of autologous blood. The effects of blood and blood clot removal or topical nicardipine, each alone and in combination of both methods, were studied and compared to untreated controls. As well clot removal alone as topical application of nicardipine without clot removal resulted in some, but statistically not significant, enlargement of the spastically narrowed basilar artery. Only the combination of both methods caused a significant vasodilatation, up to almost normal diameter range.

Symptomatic cerebral vasospasm of unusually late onset after aneurysm rupture

An unusually late occurrence of symptomatic cerebral vasospasm is reported. The case involves a 50-year-old male who was uneventfully operated on for a ruptured anterior communicating artery aneurysm, with no symptom of cerebral vasospasm, 17 days after sustaining the subarachnoid haemorrhage. Two days after surgery, a right hemiparesis developed and angiography disclosed severe cerebral vasospasm. This case history and the aetiological factors of symptomatic vasospasm are discussed.

A review of hemoglobin and the pathogenesis of cerebral vasospasm

We believe that current experimental and clinical evidence can be most satisfactorily interpreted by assuming that oxyhemoglobin is the cause of cerebral vasospasm that follows subarachnoid hemorrhage. We review the pathogenetic mechanisms by which oxyhemoglobin affects cerebral arteries. The relative importance of each of these mechanisms in the genesis of vasospasm, the biochemical pathways of oxyhemoglobin-induced smooth muscle contraction, and the intracellular actions of oxyhemoglobin on smooth muscle and on other cells in arteries are still not definitely established.

Cerebrovascular CO2 reactivity during delayed vasospasm in a canine model of subarachnoid hemorrhage

While the in vitro reactivity of cerebral conducting vessels following subarachnoid hemorrhage has been extensively studied, in vivo cerebrovascular CO2 reactivity has not been systematically investigated. We tested the hypothesis that, in the canine model of subarachnoid hemorrhage, the rise in cerebral blood flow normally seen with hypercapnia is blunted during delayed vasospasm. Four groups of animals were studied: one received two 4-ml subarachnoid injections of nonheparinized arterial blood into the cisterna magna (n = 8), one received three subarachnoid injections of 5 ml blood (n = 5), one received two subarachnoid injections of 4 ml saline (n = 5), and a control group (n = 5) had no subarachnoid injections or angiography. Basilar artery diameter was measured from baseline and follow-up angiography. We determined CO2 reactivity by randomly varying the concentration of inspired CO2 and measuring regional cerebral blood flow with radiolabeled microspheres. Basilar artery diameter was not affected by saline injection and was reduced by 26 +/- 2.9% in the two-hemorrhage group and 55 +/- 1.9% in the three-hemorrhage group. Baseline cerebral blood flow and CO2 reactivity were similar in all four groups. We conclude that, in this model of delayed vasospasm, regional cerebral vascular CO2 reactivity is intact and extrapolation of in vitro data regarding basilar artery diameter and reactivity to cerebral blood flow must be done cautiously.