The permeability change of major cerebral arteries in experimental vasospasm.

The influence of vasospasm on the permeability of the major cerebral arteries was studied using horseradish peroxidase (HRP). Experimental vasospasm was produced in canine basilar arteries by successive injections, 2 days apart, of autologous blood into the cisterna magna. HRP was injected intravenously or intracisternally 48 hours after the second injection of autologous blood, and all animals were killed by perfusion fixation 60 minutes after the injection of HRP. The distribution of HRP was observed by transmission electron microscopy. In 10 dogs injected intracisternally with HRP, 5 control dogs demonstrated a moderate amount of HRP in the intermuscular space through the adventitia. Five dogs with subarachnoid hemorrhages (SAHs) showed a moderate amount of HRP in the intermuscular space. In 11 dogs injected intravenously with HRP, 5 control dogs showed no leakage of HRP into vessel walls. Six dogs with SAHs showed HRP in the interendothelial space. These findings suggest that, despite SAHs, HRP seems to be able to circulate in the cerebrospinal fluid and makes contact with the cerebral vessels. This study suggests the possibility that spasmogenic substances may penetrate the vessel wall from the extraluminal side more easily than from the intraluminal side.     

Electron microscopy of simian cerebral arteries after subarachnoid hemorrhage and after the injection of horseradish peroxidase

A large unilateral subarachnoid hemorrhage (SAH) was created in 21 monkeys, and horseradish peroxidase (HRP) was injected into the cisterna magna or left internal carotid artery in 3 others (normals). Cerebral fixation was performed on Day 14 after SAH or 15 minutes after HRP injection. The major cerebral arteries from both the nonclot (control) and clot sides and the normal animals were examined with scanning and transmission electron microscopy (SEM and TEM). SEM of the adventitial surfaces of control and normal arteries revealed tunnel-like structures along the longitudinal axis. No vasa vasorum were seen, but adventitial rounded openings were observed, 10 to 35 micron in diameter in vessels of the anterior circulation and up to 80 micron in diameter in the basilar arteries. The stomas, numbering 5 to 10/mm of specimen, appeared to connect the subarachnoid and intraadventitial spaces or pathways. In SAH arteries, the tunica adventitia was coated with cellular remnants of hematoma or dense, well-organized blood clots, the removal of which revealed blocked stomas. TEM showed HRP in the vessel walls after injection into the cisterna magna, but not after injection into the carotid artery. TEM of control arteries revealed Virchow-Robin (intraadventitial) spaces lined by simple planar epithelium-like cells; Virchow-Robin spaces contained sparse nerve fiber bundles and connective tissue fibers. In SAH arteries, these spaces were almost filled with strands of connective tissue and fibroblasts; no nerve fibers were detected. Vasogenic substances probably reach smooth muscle cells via the adventitial stomas. SAH occluding the stomas may block the cerebrospinal fluid circulation, disturbing nutrition of the arterial wall or removal of wastes from it, thereby aggravating vasospasm.     

Barrier disruption in the major cerebral arteries during the acute stage after experimental subarachnoid hemorrhage

The effects of experimental subarachnoid hemorrhage (SAH) on the blood-arterial wall barrier in the basilar arteries were studied during the acute stage after SAH. SAH was induced in rats by injecting fresh autologous blood into the cisterna magna. Horseradish peroxidase (HRP) was given intravenously before killing the animals to assess the integrity of the barrier. In the basilar arteries taken from the animals that were killed 30 minutes after the cisternal injection of either mock cerebrospinal fluid or arterial blood, HRP reaction products were diffusely observed in the subendothelial spaces and smooth muscle layers. At 5 hours after the blood injection, no permeation of HRP into the subendothelial space was observed. Endothelial cell transcytosis seemed to be the important mechanism for HRP permeation into the subendothelial space rather than the opening of interendothelial junctions. The disruption of the blood-arterial wall barrier in the major cerebral arteries after SAH may be involved in the pathogenesis of vasospasm.     

Barrier disruption in the major cerebral arteries following experimental subarachnoid hemorrhage

The effects of experimental subarachnoid hemorrhage (SAH) on the blood-arterial wall barrier in the major cerebral arteries were studied in 20 normotensive dogs. Horseradish peroxidase (HRP) was given intravenously before the animals were sacrificed to assess the integrity of the barrier. Transient elevation of intracranial pressure (ICP) produced by cisternal injection of saline solution resulted in HRP leakage at the branching points of the major cerebral arteries. Extensive disturbance of the blood-arterial wall barrier was consistently observed in the major cerebral arteries after SAH, with or without elevation of ICP. These results suggest that both subarachnoid clot and a sudden rise in the ICP are important factors causing the breakdown of the blood-arterial wall barrier, but that the effect of the clot is the most profound. Electron microscopy revealed that opening of the interendothelial junctions is one of the important mechanisms responsible for the HRP leakage in the major cerebral arteries following SAH. Disturbance of arterial permeability in the major cerebral arteries following SAH probably accounts for the abnormal post-contrast enhancement that occurs in patients who are prone to develop vasospasm following aneurysm rupture, and is probably involved in the pathogenesis of vasospasm.     

Relaxant effect of calcitonin gene-related peptide on cerebral arterial spasm induced by experimental subarachnoid hemorrhage in dogs

This study examines the relaxant effect of calcitonin gene-related peptide (CGRP), a 37-amino acid peptide with a potent vasodilator action, on cerebral arterial spasm after subarachnoid hemorrhage (SAH). The spasm was induced by injecting autologous arterial blood percutaneously into the cisterna magna in adult mongrel dogs. The single-injection model of SAH was produced by injection of 1.0 ml/kg body weight of blood (on Day 0), and the double-injection model involved two successive injections of 0.5 ml/kg body weight of blood made 48 hours apart (on Day 0 and Day 2). On vertebral angiograms, arterial narrowing of the major cerebral arteries was most prominent on Day 3 after SAH in the single-injection model and on Day 7 in the double-injection model. When 10(-10) mol/kg of CGRP was administered intracisternally in the single-injection model on Day 3, the diameter of the spastic cerebral arteries, as determined by angiography, recovered to normal. After intracisternal administration of 10(-11) to 2 X 10(-10) mol/kg of CGRP on Day 7 in double-injection models, spastic cerebral arteries dilated in a dose-dependent manner. The dilatory effect of CGRP continued for a few hours after administration. The results suggest that CGRP injected intracisternally may reverse cerebral arterial spasm after SAH.     

SAH大鼠抗脑血管细胞增殖研究

目的 探讨大鼠SAH后脑血管细胞增殖变化,观察大鼠SAH后早期阻断VEGF的作用是否能减轻脑血管细胞增殖. 方法 72只Sprague-Dawley大鼠随机分为3组,假手术组枕大池注入NS,模型组采用枕大池二次注血法制作SAH模型,干预组在制作SAH模型的同时通过枕大池注入抗VEGF多克隆抗体.于SAH（或NS）后1、3、5、7天时处死动物,分离脑干（包含基底动脉）做形态学和PCNA免疫组化检查,观测三组大鼠基底动脉的形态学改变、基底动脉壁PCNA表达. 结果 在SAH后第1天基底动脉即出现明显血管痉挛,第3、5天达到高峰,第7天逐渐缓解.SAH模型组大鼠基底动脉壁PCNA表达第1天即开始升高,第3、5天达到顶峰,第7天后逐渐下降;NS假手术组基底动脉壁PCNA呈阴性表达;抗VEGF抗体干预组基底动脉壁PCNA呈低水平表达.枕大池注射抗VEGF抗体能缓解SAH后脑血管肌内膜增殖,减轻脑血管壁的增厚程度. 结论 VEGF介导的血管内膜增殖反应和脑血管壁增厚可能在脑血管痉挛的发生发展过程中起促进作用,SAH后早期应用VEGF拮抗剂能缓解脑血管细胞增殖.     

Posttreatment with adenovirus-mediated gene transfer of calcitonin gene-related peptide to reverse cerebral vasospasm in dogs

OBJECT: Gene transfer to cerebral vessels is a promising new therapeutic approach for cerebral vasospasm after subarachnoid hemorrhage (SAH). This study was undertaken to explore whether a delayed treatment with adenovirus encoding the prepro-calcitonin gene-related peptide (CGRP), 2 days after initial blood injection, reduces cerebral vasospasm in a double-hemorrhage model of severe vasospasm in dogs. METHODS: In 20 dogs, arterial blood was injected into the cisterna magna on Days 0 and 2. Thirty minutes after the second blood injection, the animals received either adenovirus encoding the prepro-CGRP gene (AdCMVCGRP-treated group, eight dogs) or adenovirus encoding the beta-galactosidase gene (AdCMVbeta gal-treated group, six dogs) under the cytomegalovirus (CMV) promoter. One group of dogs did not receive treatment and served as controls (control SAH group, six dogs). Angiography was performed on Days 0 and 7 to assess cerebral vasospasm. On Day 7 following angiography, the animals were killed and their brains were stained with X-gal to detect the distribution of gene expression. Cerebrospinal fluid (CSF) was also tested for CGRP immunoreactivity. Severe vasospasm was observed in control SAH dogs on Day 7, and the mean basilar artery (BA) diameter was 53.4 +/- 5.5% of the value measured on Day 0. Treatment with AdCMVbeta gal did not alter vasospasm (the BA diameter was 55 +/- 3.9% of that measured on Day 0). The leptomeninges and adventitia of the BAs of dogs treated using AdCMVbeta gal demonstrated positive staining with X-gal. High levels of CGRP were measured in CSF from dogs that received AdCMVCGRP. In the group treated with AdCMVCGRP, vasospasm was significantly reduced (the BA diameter was 78.2 +/- 5.3% of that measured on Day 0, p < 0.05 compared with the control SAH group and the AdCMVbeta gal group). CONCLUSIONS: In a model of severe vasospasm in dogs, gene transfer of CGRP after injection of blood attenuated cerebral vasospasm after SAH.     

Blood-arterial wall barrier disruption to various sized tracers following subarachnoid haemorrhage

Summary Disruption of the blood-arterial wall barrier in the major cerebral arteries occurs following subarachnoid haemorrhage (SAH) and may be related to the pathogenesis of cerebral vasospasm. Using FITC dextrans of various sizes, the present study was undertaken to determine if the barrier disruption shortly after SAH occurs equally to various sized tracers. Forty-two Sprague-Dawley rats were divided into 5 groups. Four groups were injected with FITC-dextrans of differing molecular weights (MW): FD4 (MW=4,080), FD40 (MW=40,500), FD 70 (MW=71,400), and FD 150 (MW=156,900). One group was injected with horseradish peroxidase (HRP: MW=40,000). Each group was further divided into two subgroups: with or without SAH. SAH was induced by injecting arterial blood into the cisterna magna. To assess the integrity of the blood-arterial wall barrier by transmission electron microscope, the tracers were intravenously injected prior to sacrificing the animals. The groups without SAH showed no permeability of tracers into the subendothelial spaces of the basilar arteries. In contrast, with the exception of FD 150, FITC-dextrans (FD 4, FD 40, FD 70) were noticed in the subendothelial spaces. The distribution of FITC-dextrans in the elastic lamina was similar to that of HRP. These results suggest that barrier disruption occurs with a wide range of molecular sizes of FITC-dextrans, although there seems to be some limitation to the permeation of the larger molecules. The present study suggests that the mechanism of barrier disruption of the major cerebral arteries in the acute stage following SAH may be vesicular rather than by separation of tight junctions.     

Time course of the blood-arterial wall barrier disruption following experimental subarachnoid haemorrhage

Summary The time course of the blood-arterial wall barrier disruption following experimental subarachnoid haemorrhage (SAH) was studied in 24 rabbits. Animals with SAH received two successive blood injections through the cisterna magna. Horseradish peroxidase (HRP) was given intravenously 30 minutes before sacrifice to assess the integrity of the barrier. In the basilar arteries taken from animals that were sacrificed 4 days after the first SAH, HRP-reaction products were diffusely observed in the subendothelial space. Three weeks following the first SAH, permeation of HRP was still observed in half of the animals. However, in animals sacrificed 7 weeks after the first SAH, no permeation of HRP into the subendothelial space was noted. Opening of the interendothelial space seemed to be the major mechanism for HRP permeation into the subendothelial space rather than transendothelial vesicular transport. Disruption of the bloodarterial wall barrier in the major cerebral arteries following SAH may play a role in the pathogenesis of vasospasm.     

Efficacy of intrathecal liposomal fasudil for experimental cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE: To investigate the safety and efficacy of liposomal fasudil in a sustained-release form for the prevention of cerebral vasospasm after subarachnoid hemorrhage (SAH). METHODS: Eighteen rats were divided into three groups, each of which received 2.5 mg/kg of liposomal fasudil, 5 mg/kg of liposomal fasudil, or drug-free liposomes after SAH. Next, experimental SAH was induced in 15 dogs by injection of autologous arterial blood into the cisterna magna twice after baseline vertebral angiography. In six dogs, 0.94 mg/kg of liposomal fasudil was injected into the cisterna magna (treatment group). In four dogs, drug-free liposomes were similarly injected (placebo group), and the remaining five dogs were not treated with liposomal injection after SAH (control group). Angiography was repeated on Day 7, and cerebrospinal fluid was collected before the dogs were killed. RESULTS: A high dose of liposomal fasudil caused no significant changes in mean arterial blood pressure and did not induce seizures during the observation period. Gross and microscopic examination of the brains revealed no abnormalities, but severe vasospasm was noted in the rat basilar artery, mainly in the group treated with drug-free liposomes. Likewise, in the canine placebo and control groups, significant vasospasm occurred in the basilar artery on Day 7. In the treatment group, vasospasm in the basilar artery was significantly ameliorated (P < 0.01). In vivo, 90% of fasudil was released from liposomes in the cerebrospinal fluid. CONCLUSION: A single injection of intrathecal liposomal fasudil is safe and effective for the prevention of vasospasm in experimental SAH.     

Delayed CSF lavage for arteriographic and morphological vasospasm after experimental SAH

Irrigation of the subarachnoid space after aneurysmal subarachnoid hemorrhage (SAH) has been reported to alleviate subsequent arterial vasospasm. The authors have investigated the effect of lavage of the cerebrospinal fluid (CSF) space in the two-hemorrhage canine model of vasospasm. Twelve dogs had basilar cistern lavage with 120 cc of artificial CSF 24 hours after each of two SAH's, and 12 control dogs had two sequential SAH's without intervening lavage of clot. The amount of clot on the ventral brain stem was evaluated at sacrifice and was graded from 0 (no clot) to 4 (maximum clot) to assess the adequacy of clot removal. Dogs that had undergone lavage had a median grade of 1 (range Grade 0 to 2); control dogs had a median grade of 2 (range Grade 1 to 3.5, p less than 0.001. Wilcoxon rank sum test), indicating significant reduction of gross clot by lavage. The neurological findings were graded from 0 to 5, based on meningismus, ataxia, paresis, and cranial nerve deficits. No significant differences in neurological grade were found on any day between the two groups. Satisfactory angiograms were obtained before and 7 days after hemorrhage and were controlled for blood pressure and blood gases; these showed significant spasm in both groups. There was a mean reduction (+/- standard deviation) of 21.6% +/- 16.2% in basilar artery diameter in control dogs, compared to a 28.8% +/- 15.1% reduction in dogs with lavage (difference not significant, t-test). There was a strong, but insignificant, trend toward reduction of endothelial desquamation in the basilar and middle cerebral arteries in dogs with lavage compared to control animals (p = 0.06). Corrugation and tearing of the elastica, thickened intima, intimal fibroplasia, vacuolization of the endothelial or smooth-muscle cells, and presence of blood cells in the adventitia occurred similarly in both groups. It appears that cisternal lavage 24 hours after hemorrhage in this model has no effect on the angiographic, neurological, or most morphological sequelae of SAH, in spite of evidence for removal of clot as seen at sacrifice. Any postulated interaction of clot and vessel resulting in chronic vasospasm must occur before this time. Evaluation of the effect of much earlier lavage (for instance, 1 hour after hemorrhage) may elucidate the point at which vasospasm is instigated after SAH, and help in determining what factors cause vasospasm.     

Effect of high-dose methylprednisolone on vasospasm after subarachnoid hemorrhage.

The effects of high-dose methylprednisolone (MP) on vasospasm following subarachnoid hemorrhage (SAH) were investigated. In a double hemorrhage canine model, administration of high-dose MP (10 mg/kg, every 12 hours) reduced angiographic narrowing of the basilar artery and prevented morphological changes in the arterial wall. In addition, increased platelet aggregation observed from days 4 to 7 in untreated SAH dogs was inhibited by the MP treatment. An in vitro experiment showed that MP inhibited platelet aggregation dose-dependently. High-dose MP had a nonspecific vasodilatory effect on the smooth muscle of the basilar artery. In another SAH model with dysautoregulation of cerebral blood flow (CBF), intravenous MP administration markedly attenuated the decrease in both blood pressure and CBF caused by exsanguination. These results indicate that MP has beneficial effects in normalizing CBF dysautoregulation following SAH. High-dose MP has several advantages for preventing and improving the multiple pathological status in cerebral vasospasm following SAH.     

Barrier disruption in the major cerebral arteries after experimental subarachnoid hemorrhage in spontaneously hypertensive and normotensive rats

The effects of experimental subarachnoid hemorrhage (SAH) on the blood-arterial wall barrier in the major cerebral arteries were studied in 24 spontaneously hypertensive rats (SHR) and 13 Sprague-Dawley rats (SDR). Horseradish peroxidase (HRP) was given intravenously before killing the animals to assess the integrity of the barrier. In the acute experimental group, transient elevation of intracranial pressure (ICP) and systemic arterial pressure produced by cisternal injection of whole blood, saline solution, or Elliott's B solution resulted in extensive disturbance of the blood-arterial wall barrier. In the chronic group, only the cisternal injection of whole blood in SHR brought about an extensive and marked disturbance of the arterial permeability. These results suggest that: (a) early breakdown of the blood-arterial wall barrier seems to be due to a sudden rise in the ICP or arterial pressure; (b) in the chronic experiments, the subarachnoid clot is the most important factor responsible for the permeability changes; and (c) in the chronic SAH experiments, the blood-arterial wall barrier seems to be more vulnerable in SHR than in Sprague-Dawley rats. Due to the well-known similarities between SHRs and hypertensive human beings, patients with chronic hypertension should be considered at high risk after SAH for extensive blood-arterial wall barrier disturbances.     

Cytoskeletal and extracellular matrix proteins in cerebral arteries following subarachnoid hemorrhage in monkeys.

It is unclear if vasospasm after subarachnoid hemorrhage (SAH) is predominantly due to smooth-muscle contraction, proliferative vasculopathy, or other changes within the arterial wall such as fibrosis or change in smooth-muscle phenotype. In this study, immunohistochemistry was used to examine changes in extracellular and cytoskeletal proteins in cerebral arteries after SAH that might support one of these mechanisms. Following baseline cerebral angiography, bilateral SAH was created in nine monkeys. Three animals each were killed 7, 14, or 28 days after SAH. Cerebral angiography was repeated on Day 7 in all animals and immediately prior to sacrifice in animals killed on Days 14 and 28. Both middle cerebral arteries and four control basilar arteries were examined using fluorescent antibody techniques with antisera to alpha-actin, myosin, fibronectin, fibrinogen, vimentin, desmin, laminin, and collagens (types I, III, IV, and V). Angiography showed that vasospasm was most severe on Day 7, present but resolving on Day 14, and completely resolved by Day 28. Microscopic study of arterial sections and blinded review of microphotographs of arterial sections by five independent observers did not reveal changes in intensity of density of staining for collagens, desmin, myosin, laminin, or alpha-actin in the tunica media of tunica adventitia. Fibronectin immunoreactivity increased 14 days after SAH. Seven days after SAH, occasional areas of tunica media showed immunoreactivity to fibrinogen. On Day 28, intimal thickening was observed in four of six middle cerebral arteries and this tissue demonstrated immunoreactivity to alpha-actin, myosin, vimentin, desmin, fibronectin, laminin, and each type of collagen. No significant increases in the number of intimal cells showing immunoreactivity to alpha-actin were seen and no significant changes in the hydroxyproline content of cerebral arteries developed at any time after SAH. These results suggest that rigidity and lumen narrowing of vasospasm are not due to increased arterial collagen, although other proteins in the arterial wall or an alteration in cross-linking of existing proteins could produce these changes. There is no indication that smooth-muscle contractile proteins change during vasospasm or that increases in the number of alpha-actin-containing myointimal cells contribute to vasospasm. The occurrence of intimal thickening and increased tunica media fibronectin after vasospasm suggests that vasospasm damages smooth muscle, possibly as a result of intense prolonged smooth-muscle contraction.     

Subarachnoid Heamorrhage-Induced Chronic Cerebral Vasospasm in the Rabbit: IV-DSA Versus IA-DSA

Summary.  Background: Chronic cerebral vasospasm is delayed-onset cerebral arterial narrowing in response to blood clots left in the subarachnoid space after aneurysmal subarachnoid haemorrhage (SAH). Rabbit models of vasospasm have been developed as in vivo experimental pathogenesis and the treatments of cerebral vasospasm using human vessels are not possible. The present study assessed the diagnostic accuracy of the intravenous digital subtraction angiography (IV-DSA) in chronic cerebral arterial spasm following induced SAH in the rabbit.  Method: Ten rabbits' left leg veins catheterised by intravascular access needle and 3F catheters introduced to the right leg arteries probing the proximal of the vertebral arteries. Initially IV-DSA and intra-arterial digital subtraction angiography (IA-DSA) was performed. Three millilitres of fresh autologous arterial blood was injected into the cisterna magna of the ten rabbits' in order to produce in vivo model of chronic SAH. Angiograms were obtained 15 minutes and 72 hours after the SAH.  Findings: Diameters of the basilar arteries were similar to each other in both methods and reduced after the SAH.  Interpretation:The present study shows that IV-DSA is a relatively simple and effective method for demonstrating cerebral vessels, especially the basilar artery. Published online September 2, 2002 Correspondence: Tanzer Sancak M.D., Mesa Camyolu sitesi, B1 Blok A17 Yenikent, Cayyolu, Ankara, Turkey.     

Cerebral arterial responses to induced hypertension following subarachnoid hemorrhage in the monkey.

Regional cerebral blood flow (rCBF), angiographic cerebral arterial caliber, and cerebrospinal fluid (CSF) pressure were measured in rhesus monkeys to determine the effect of experimentally induced subarachnoid hemorrhage (SAH) on cerebral arterial responses to graded increases in blood pressure. These measurements were also performed in a control group of monkeys subjected to a mock SAH by injection of artificial CSF into the cerebral space. Before subarachnoid injection of blood or artificial CSF, graded increases in mean arterial blood pressure (MABP) to a level 40% to 50% above baseline values had no effect on rCBF. The major cerebral arteries constricted and CSF pressure remained unchanged. Similar responses were observed after injections of artificial CSF. When MABP was increased in animals that had been subjected to subarachnoid injection of blood, rCBF increased and was associated with dilatation of the major cerebral arteries and moderate increases in CSF pressure. These results demonstrate that cerebral arterial responses to increases in blood pressure may be abnormal in the presence of subarachnoid blood. The manner in which abnormal cerebral arterial reactivity, changes in blood pressure, and vasospasm combine to determine the level of cerebral perfusion following SAH is postulated.     

Penetrating atheroma in cervical carotid artery stenosis

A 61-year-old male presented with left hand motor weakness associated with cerebral infarction in the right frontal lobe. Right common carotid angiography demonstrated a 66% stenosis and carotid duplex scan demonstrated intermediate echogenic plaque, indicating typical carotid plaque. Carotid endarterectomy was performed 22 weeks after the ischemic onset. During exposure of the carotid artery, a soft and yellowish mass (5 x 5 mm) was observed in the lateral wall of the carotid bulbus, which was not covered with adventitia but with thin connective tissue. The mass was removed en-bloc with a small part of the surrounding arterial wall combined with ordinary endarterectomy. The artery was closed with a collagen-impregnated polyester patch graft (Hemashield patch) to maintain adequate arterial lumen. Histological examination of the removed plaque confirmed that atheroma had protruded from the intima through the media as well as the adventitia and formed an extra-arterial mass. Such a case requires great care to dissect the carotid artery to prevent premature disintegration of the atheroma.     

Heme oxygenase-1 gene therapy for prevention of vasospasm in rats

OBJECT: Hemoglobin causes contraction of cerebral arteries and is also believed to cause vasospasm after subarachnoid hemorrhage (SAH). The goal in this study was to determine if overexpression of heme oxygenase-1 (HO-1), the principal enzyme involved in the metabolism of hemoglobin, would reduce contractions of cerebral arteries brought on by hemoglobin and decrease vasospasm after experimental SAH. METHODS: Injection of adenovirus expressing HO-1 (Ad5HO-1) into the cisterna magna of rats produced a significant increase in expression of HO-1 messenger RNA, and protein and HO-1 activity in the basilar artery ([BA]; p < 0.05 for each measure compared with vehicle and/or control virus, according to analysis of variance or unpaired t-test). Injection of adenovirus expressing beta-galactosidase (Ad-betaGal) produced only mild, statistically nonsignificant increases. The HO-I immunoreactivity was localized to the BA adventitia after injection of Ad5HO-1 or Ad-betaGal. Injection of Ad5HO-1 and Ad-betaGal increased the baseline diameter of the BA (measured directly via a transclival window) and brainstem cerebral blood flow (CBF), measured by laser Doppler flowmetry, compared with vehicle. Contraction of the BA after addition of hemoglobin was significantly inhibited, reduction in brainstem CBF was significantly prevented, and carboxyhemoglobin concentration was significantly increased in rats injected with Ad5HO-1 compared with Ad-betaGal and vehicle. Vasospasm was significantly ameliorated in rats in which Ad5HO-1 was injected into the cisterna magna at the time of SAH in a double-hemorrhage model. CONCLUSIONS: These results show that overexpression of HO-1 inhibits arterial contractions induced by hemoglobin and can reduce vasospasm after experimental SAH.     

Is vasospasm related to proliferative arteriopathy?

Although proliferative arteriopathy has been postulated to play a role in the etiology of vasospasm after subarachnoid hemorrhage (SAH), histological and morphological studies examining cerebral vasospasm have produced conflicting results. To help settle this controversy, the authors used an in vivo label of cell division, bromodeoxycytidine, to assess cell proliferation in a primate model of SAH. Fifteen cynomolgus monkeys received a clot of either whole blood (11 animals) or red blood cells (four animals) placed around the right middle cerebral artery (MCA). On the day of surgery continuous intravenous infusion of bromodeoxycytidine was begun and continued until the animal was sacrificed immediately after arteriography on Day 7, 12, or 27 following surgery. Sections from the right and left MCA's were stained with a monoclonal antibody against bromodeoxcytidine, and labeled cells were counted. Arteriographic evidence of vasospasm occurred in nine monkeys on Day 7. On Day 12 and Day 27 no monkeys had persistent vasospasm. Placement of subarachnoid clot around the right MCA increased proliferative activity across all layers of the arterial wall. Most of the labeled cells were in the adventitia and the endothelium. Although there were more dividing cells in all layers of the right MCA than the left MCA (p < 0.01), the number of stained cells per section was limited (range 0.1 to 21.2, mean 8) and the occurrence of vasospasm was not associated with the number of dividing cells in the right MCA on Day 7, 12, 27, or for all days combined (p > 0.6). Cerebral vasospasm after SAH was not associated with the extent of proliferation of cells in the vessel wall, nor could the intensity of the limited proliferative changes have been responsible for narrowing of the vessel diameter.     

Preferential localization of varying forms of photoactive 1, 8-naphthalimide compounds within the atheromatous arterial wall

BACKGROUND AND OBJECTIVE: We are currently working with a novel class of photoactivated 4-amino substituted 1,8-naphthalimide compounds for tissue bonding. With promising results in other tissues, we are pursuing potential vascular applications. This study focused on determining the appropriate compound formulation(s), concentration, and exposure times to optimize penetration of the heterogeneous arterial wall. STUDY DESIGN/MATERIALS AND METHODS: Segments of atheromatous rabbit carotid artery were immersed in hydrophilic or lipophilic forms of the compound, then frozen, cryosectioned, and examined by confocal microscopy. RESULTS: The hydrophilic compound exhibited preferential localization within the intima and media and limited presence in the adventitia. Conversely, the lipophilic compound concentrated in the intima and adventitia with virtual exclusion from the media. Exposure to both forms resulted in complete penetration of the arterial wall. CONCLUSION: These results extend our knowledge and permit a more practical approach to potential vascular applications using these photoactivated compounds for tissue bonding.