Long-term outcome after endovascular treatment of cavernous sinus dural arteriovenous fistula and a literature review.

BACKGROUND: The long-term efficacy of endovascular treatment (EVT) for cavernous sinus dural arteriovenous fistulae (CS-dAVF) was assessed with a special focus on residual shunts after initial EVT. PATIENTS AND METHODS: This retrospective survey included 50 patients who had undergone EVT and were followed for 1 month or longer (median follow-up 56 months). RESULTS: Common preoperative symptoms were chemosis (78%), extra-ocular motor palsy (72%), exophthalmos (66%), and tinnitus (26%). CS-dAVF were addressed by transvenous embolization (tVE, n = 48), tVE only was used in 43 instances and tVE plus transarterial embolization (tAE) in five. Two patients underwent tAE only. Procedure-related morbidity (brainstem infarction) was recorded in one patient (2%) and transient symptom exacerbation (paradoxical worsening) in 12 patients (24%). Postoperative digital subtraction angiography showed no major retrograde shunt or cortical venous reflux in any of the 50 patients. Anterograde or minor retrograde residual shunt was observed in 17 patients (34%); three of these underwent additional tVE and four had Gamma Knife surgery. The shunt flow disappeared in all 17 patients 12.6 ± 13.4 (mean ± SD) months after initial EVT. At the latest follow-up, 65.7 ± 52.6 months after the initial operation, no shunt flow was observed in any of the 50 patients. None had remaining or newly developed chemosis or tinnitus on follow-up. The rate of persistent cavernous sinus symptoms at the latest follow-up was higher in patients with than without post-procedural paradoxical worsening (5/12, 41.7% vs. 2/38, 5.3%, p = 0.0059 by Fisher's exact test). CONCLUSIONS: Long-term follow-up showed that EVT, especially tVE, is an efficient and safe treatment for CS-dAVF. It resulted in the eventual disappearance of shunt flow. Residual shunt without major retrograde flow or cortical venous reflux can be monitored without additional treatment.

Effect of Revascularization on Headache Associated with Moyamoya Disease in Pediatric Patients.

Episodic headache is common in childhood moyamoya disease (MMD). The onset, mechanism, cause of headache and the effect of revascularization surgery on headache are not yet clear. We studied 10 cases of children (7 boys and 3 girls) younger than 18 years who underwent revascularization for MMD between 2009 and 2013. We evaluated frequency of headache and cerebral blood flow changes by single photon emission computed tomography brain imaging with [I123]-labeled iofetamine (IMP-SPECT) before and after surgery. Patients' ages ranged from 0 to 15 years at onset and 2 to 17 years at the time of surgery, mean age being 6.7 and 8.0 years respectively. 9 of 10 patients presented with ischemic symptoms and 8 had headache. 5 patients underwent indirect bypass and 5 underwent combined direct and indirect bypass. Cerebral blood flow improvement was obtained in 14 of the 15 cerebral hemispheres revascularized. The mean follow-up duration was 32.9 months. All the patients had good outcomes with improvement of ischemic neurological deficits. Headache improved in 7 (87.5%) of 8 patients. Headache in pediatric moyamoya disease is associated with change in cerebral hemodynamics. Revascularization including combined direct bypass and indirect techniques may be required to reduce headache in patients with MMD.

Clinical presentation and treatment of distal anterior inferior cerebellar artery aneurysms.

Aneurysms located at the distal portion of the anterior inferior cerebellar artery (AICA) are rare, and their clinical features are not fully understood. We report the clinical features and management of nine distal AICA aneurysms in nine patients treated during the past decade at Kagoshima University Hospital and affiliated hospitals. Our series includes seven women and two men. Of their nine aneurysms, eight were ruptured and one was unruptured; six were saccular and three were dissecting aneurysms. The most prevalent location was the meatal loop (n = 5) followed by the postmeatal (n = 3) and premeatal segment (n = 1) of the AICA, suggesting hemodynamic stress as an etiology of these distal AICA aneurysms. Of the nine patients, five presented with angiographic features suggestive of increased hemodynamic stress to the AICA and the common trunk of the posterior inferior cerebellar artery, with vertebral artery stenosis, marked laterality, and a primitive hypoglossal artery. We addressed eight aneurysms (eight patients) surgically; one aneurysm in one patient disappeared in the course of 3 months without surgical treatment. Of the eight surgically treated aneurysms, seven were ruptured and one was unruptured, five were clipped via lateral suboccipital craniotomy, two were trapped via lateral suboccipital craniotomy, and one was embolized. Good outcomes were obtained in six of the eight patients who underwent operation (75 %). We consider increased hemodynamic stress attributable to anatomic variations in the AICA and related posterior circulation to be the predominant contributor to the development of distal AICA aneurysms. Direct clipping and trapping yielded favorable outcomes in our series.

Clinical presentation and treatment of distal posterior inferior cerebellar artery aneurysms.

Aneurysms located at the distal portion of the posterior inferior cerebellar artery (PICA) are rare, and their clinical features are not fully understood. We report the clinical features and management of 30 distal PICA aneurysms in 28 patients treated during the past decade at Kagoshima University Hospital and affiliated hospitals. Our series includes 20 women and eight men. Of their 30 aneurysms, 24 were ruptured, and six were unruptured; there were 27 saccular and two fusiform aneurysms; one was dissecting. Their location was at the anterior-medullary (n = 4), lateral-medullary (n = 9), tonsillomedullary (n = 7), telovelotonsillar (n = 6), and cortical (n = 4) segment of the PICA. In 18 patients, angiographic features suggested hemodynamic stress including an absent contralateral PICA or ipsilateral anterior inferior cerebellar artery, termination of the vertebral artery (VA) at the PICA, and hyperplasia or occlusion of the contralateral VA. As three patients died before surgery, 27 aneurysms in 25 patients were surgically treated. Of these, 6 were unruptured aneurysms; 20 were clipped via midline or lateral suboccipital craniotomy, and 5 were embolized with Guglielmi coils; in one, the PICA flow was reconstructed by OA-PICA anastomosis, and in the other one, the PICA was resected. Of the 25 surgically treated patients, 22 (88%) had good outcomes. The predominant contributor to the development of distal PICA aneurysms is thought to be increased hemodynamic stress attributable to anomalies in the PICA and related posterior circulation. Both direct clipping and coil embolization yielded favorable outcomes in our series. However, considering the difficulties that may be encountered at direct clipping in the acute stage and the availability of advanced techniques and instrumentation, aneurysmal coiling is now the first option to address these aneurysms.

The cyclooxygenase site, but not the peroxidase site of cyclooxygenase-2 is required for neurotoxicity in hypoxic and ischemic injury.

Cyclooxygenase-2 (COX-2) activity has been implicated in the pathogenesis of ischemic injury, but the exact mechanisms responsible for its toxicity remain unclear. Infection of primary neurons with an adenovirus expressing wild type (WT) COX-2 increased the susceptibility of neurons to hypoxia. Infection with an adenoviral vector expressing COX-2 with a mutation at the cyclooxygenase site did not increase susceptibility to hypoxia, whereas over-expression of COX-2 with a mutation in the peroxidase site produced similar susceptibility to hypoxia as WT COX-2. Primary neuronal cultures obtained from transgenic mice bearing a mutation in the COX-2 cylooxygenase site were protected from hypoxia. Mice with a mutation in the cyclooxygenase site had smaller infarctions 24 h after 70 min of middle cerebral artery occlusion than WT control mice. COX-2 activity had no effect on the formation of protein carbonyls. Ascorbate radicals were detected by electron paramagnetic resonance as a product of recombinant COX-2 activity and were blocked by COX-2 inhibitors. Similarly, formation of ascorbate radicals was inhibited in the presence of COX-2 inhibitors and in homogenates obtained from COX-2 null mice. Taken together, these results indicate that the cyclooxygenase activity of COX-2 is necessary to exacerbate neuronal hypoxia/ischemia injury rather than the peroxidase activity of the enzyme.

The effects of the phosphodiesterase inhibitor olprinone on global cerebral ischemia.

BACKGROUND: The phosphodiesterase III inhibitor olprinone has been confirmed to improve myocardial function and increase cerebral blood flow; therefore, if olprinone exerts direct neuroprotective effects against global cerebral ischemia to the same degree as cilostazol, olprinone could be useful for cerebral resuscitation after cardiac arrest. We examined whether olprinone directly protected neuronal cells from global cerebral ischemia both in vivo and in vitro. METHODS: In a rat model of 10-minute global cerebral ischemia induced by 4-vessel occlusion, 0.3, 3, or 30 microg x kg(-1) x min(-1) olprinone or saline was infused for a periischemic period of 40 minutes (n = 6 for each group). Hippocampal CA1 neuronal cells were then counted 3 days after reperfusion, and the phosphorylation of cyclic adenosine 3'5'-monophosphate response element-binding protein was examined using Western blotting analyses of specimens obtained 15 minutes after reperfusion. In vitro, cultured cerebral neurons were exposed to 4 hours of hypoxia and glucose deprivation and then 24 hours of recovery in the absence or presence of olprinone (10(-11)-10(-5) mol x L(-1)). Cell viability was measured using the Cell Counting Kit-8 (Dojindo Molecular Technologies, Gaithersburg, MD). RESULTS: In the rat model of global ischemia, the number of surviving CA1 neurons counted under a microscopic field in the 30 microg x kg(-1) x min(-1) olprinone-treated group (49.9 +/- 9.2) was significantly higher than that in the saline infusion control group (7.2 +/- 3.4), and olprinone treatment increased the phosphorylation of cyclic adenosine 3'5'-monophosphate response element-binding protein. The survival fraction of the neuronal cells cultured in the presence of olprinone was also significantly higher than that of cells cultured in the absence of olprinone in a dose-dependent manner. CONCLUSIONS: Our study successfully demonstrated, for the first time, that olprinone had a protective effect on neuronal cells in vitro and in vivo, especially against global cerebral ischemia. These results suggest that olprinone might be useful for the treatment of patients experiencing global cerebral ischemia.

Changes in tissue factor and the effects of tissue factor pathway inhibitor on transient focal cerebral ischemia in rats.

INTRODUCTION: To determine the contribution of tissue factor (TF) to focal cerebral ischemia/reperfusion injury, we investigated the changes in TF in rat brains with transient focal cerebral ischemia and also assessed the effect of TF pathway inhibitor (TFPI). MATERIALS AND METHODS: Spontaneous hypertensive rats were subjected to 90-min of middle cerebral artery occlusion (MCAO) and then were reperfused for up to 24 h. Immediately after MCAO, recombinant human TFPI (rhTFPI) (50 or 20 microg/kg/min) was administered by means of a continuous intravenous injection for 4.5 h. RESULTS AND CONCLUSIONS: TF immunoreactivity decreased or scattered in the ischemic area after reperfusion, however, an increased TF expression was observed in the microvasculature with the surrounding brain parenchyma and it peaked at 3 to 6 h, which coincided with the start of fibrin formation. On the other hand, total TF protein in ischemic area continued to exist and did not remarkably change until 24 h after reperfusion. At 24 h after reperfusion, the total infarct volume in the group treated with 50 microg/kg/min rhTFPI was significantly smaller than that in the controls (saline). Western blotting and immunohistochemical studies showed that rhTFPI treatment resulted in a decrease of fibrin in the ischemic brains and microvasculature. TF-mediated microvascular thrombosis is thus considered to contribute to focal cerebral ischemia/reperfusion injury. The continuous infusion of rhTFPI until a peak of TF-mediated microvascular thrombosis therefore attenuates the infarct volume by reducing fibrin deposition in the cerebral microcirculation.

C-type natriuretic peptide is specifically augmented by pituitary adenylate cyclase-activating polypeptide in rat astrocytes.

In rat-cultured astrocytes, pituitary adenylate cyclase-activating polypeptide (PACAP) activates gene expression and secretion of C-type natriuretic peptide (CNP) in a dose- and time-dependent manner. These results suggest that PACAP might be involved in the regulation of CNP biosynthesis in astrocytes.

Primary squamous cell carcinoma of the frontal sinus.

We report a 74-year-old Japanese man with squamous cell carcinoma (SCC) originating in the frontal sinus. It presented as a cutaneous nodule on his right forehead. Magnetic resonance imaging (MRI) revealed invasion of the anterior wall of the ethmoid sinus, the frontal bone, and possibly the meninx by a frontal sinus carcinoma. Despite right fronto craniotomy with en bloc resection followed by two courses of radiation therapy and chemotherapy with 5-fluorouracil and nedaplatin or TS-1 he died of disease-related causes 20 months later. Herein, we present a detailed description of this patient and a review of the published work.

The environment of increased concentration of docosahexaenoic acid in glioblastoma may suppress the anti-tumor effect of macrophages.

Regarding glioblastoma, there has been controversy over whether a large number of infiltrating macrophages act as anti-tumor effectors or not. It has been exhibited that intratumoral lipid environments have a possible influence on anti-tumor immunity. Necrosis of glioblastoma and non-necrotic tissues of astrocytic tumors were analyzed to compare the amount of free docosahexaenoic acid (DHA) content. The apoptosis inducible effects of DHA on macrophages derived from peripheral blood monocytes and cultured glioma cells were evaluated by flow cytometry. The influence of DHA on the anti-tumor effects of macrophages was assessed at 0, 30, 60, and 90 mM of DHA by (51)Cr releasing assay and MTT assay. The mean concentration of free DHA in necrotic tissues (757.6 mmol/kg) was 5 times higher than that in non-necrotic tissues (147.2 mmol/kg). The DHA concentration of 30 mM induced apoptosis in macrophages, however, glioma cells were not affected even at a DHA concentration of 60 mM. Macrophages pre-exposed to DHA for 24 h decreased the cytotoxicity to U251MG cells as shown by (51)Cr releasing assay. Total viability of co-cultured macrophages and U251MG cells showed an increase at high concentrations of DHA (60 and 90 mM) according to 24 h MTT assay, although each separate culture did not. The DHA concentration in necrosis of glioblastoma was sufficient for macrophages to cause apoptosis and suppress their anti-tumor effects. The results suggest that liberated DHA in necrosis can induce apoptosis in macrophages and inhibit their functions.

Cloning and characterization of rat caspase-9: implications for a role in mediating caspase-3 activation and hippocampal cell death after transient cerebral ischemia.

Delayed hippocampal neurodegeneration after transient global ischemia is mediated, at least in part, through the activation of terminal caspases, particularly caspase-3, and the subsequent proteolytic degradation of critical cellular proteins. Caspase-3 may be activated by the membrane receptor-initiated caspase-8-dependent extrinsic pathway and the mitochondria-initiated caspase-9-dependent intrinsic pathway; however, the precise role of these deduced apoptosis-signaling pathways in activating caspase-3 in ischemic neurons remains elusive. The authors cloned the caspase-9 gene from the rat brain and investigated its potential role in mediating ischemic neuronal death in a rat model of transient global ischemia. Caspase-9 gene expression and protease activity were extremely low in the adult brain, whereas they were developmentally upregulated in newborn rats, especially at postnatal 12 weeks, a finding consistent with the theory of an essential role for caspase-9 in neuronal apoptosis during brain development. After 15-minute transient global ischemia, caspase-9 was overexpressed and proteolytically activated in the hippocampal CA1 neurons at 8 to 72 hours of reperfusion. The temporal profile of caspase-9 activation coincided with that of cytochrome c release and caspase-3 activation, but preceded CA1 neuronal death. Immunoprecipitation experiments revealed that there was enhanced formation of Apaf-1/caspase-9 complex in the hippocampus 8 and 24 hours after ischemia. Furthermore, intracerebral ventricular infusion of the relatively specific caspase-9 inhibitor N-benzyloxycarbonyl-Leu-Glu-His-Asp-fluoro-methylketone before ischemia attenuated caspase-3-like activity and significantly enhanced neuronal survival in the CA1 sector. In contrast, inhibition of caspase-8 activity had no significant effect on caspase-3 activation or neuronal survival. These results suggest that the caspase-9-dependent intrinsic pathway may be the primary mechanism responsible for the activation of caspase-3 in ischemic hippocampal neurons.

Inducible repair of oxidative DNA lesions in the rat brain after transient focal ischemia and reperfusion.

To determine the role of oxidative DNA damage and repair in brain injury after focal ischemia and reperfusion, the authors investigated DNA base damage and DNA base excision repair (BER) capacity, the predominant repair mechanism for oxidative DNA lesions, in the rat model of temporary middle cerebral artery occlusion. Contents of 8-hydroxyl-2'-deoxyguanosine (8-oxodG) and apurinic/apyrimidinic abasic site (AP site), hallmarks of oxidative DNA damage, were quantitatively measured in nuclear DNA extracts from brains 0.25 to 72 hours after 1 hour of middle cerebral artery occlusion. In parallel to the detection of DNA lesions, the capacity for 8-oxodG- or AP site-dependent DNA repair synthesis was measured in nuclear protein extracts using specific in vitro DNA repair assays. After postischemic reperfusion, the levels of 8-oxodG and AP sites were markedly increased in ischemic tissues. In frontal/parietal cortex, regions that survived ischemia, 8-oxodG and AP sites were efficiently repaired during reperfusion. However, in the caudate, a region that was destined to infarct, the DNA lesions were poorly repaired. In consistent with the patterns of endogenous lesion repair, a markedly induced and long-lasting (at least 72 hours) BER activity was detected in the cortex but not in the caudate after ischemia. The induced BER activity in ischemic cortex was attributed to the upregulation of gene expression and activation of selective BER enzymes, particularly DNA polymerase-beta and OGG1. These results strongly suggest that inducible DNA BER constitutes an important endogenous mechanism that protects brain against ischemia-induced oxidative neuronal injury.

Intractable hiccups as a presenting symptom of cerebellar hemangioblastoma. Case report.

The authors report on a 52-year-old woman with a cerebellar hemangioblastoma who presented with a 2-year history of intractable hiccups. Computerized tomography scans and magnetic resonance images revealed a cerebellar hemangioblastoma with compression of the brainstem at the level of the medulla oblongata. The patient has been free of hiccups and has been neurologically intact since the day after total removal of the tumor. A review of the literature on medullary lesions presenting with intractable hiccups is provided.

Tumefactive myelinoclastic diffuse sclerosis--case report.

A 6-year-old boy presented with mental disturbance and progressive left hemiparesis. Magnetic resonance imaging demonstrated large intracranial mass lesions with ring-like enhancement. His neurological condition deteriorated rapidly. Open biopsy via craniotomy was performed under the suspicion of tumor. Histological examination showed massive demyelination and axon preservation, but no tumor cells. The diagnosis was myelinoclastic diffuse sclerosis (MDS). He was treated with high-dose methylprednisolone and improved dramatically. MDS is a rare demyelinating disorder of the central nervous system that affects mainly children and may mimic a brain tumor. MDS must be included in the differential diagnosis in young patients with a brain tumor with atypical radiological appearance.

C-type natriuretic peptide modulates permeability of the blood-brain barrier.

C-type natriuretic peptide (CNP) is abundant in brain and is reported to exert autocrine function in vascular cells, but its effect on blood-brain barrier (BBB) permeability has not been clarified yet. Here, we examined this effect. Transendothelial electrical resistance (TEER) of in vitro BBB model, composed of bovine brain microvascular endothelial cells and astrocytes, was significantly dose dependently decreased by CNP (1, 10, and 100 nmol/L). C-type natriuretic peptide treatment reduced both the messenger RNA (mRNA) and protein expressions of tight junction (TJ) protein zonula occludens-1 (ZO-1). The effects on TEER, mRNA, and protein expressions of ZO-1 were mimicked by cyclic GMP (cGMP) analog 8-bromo-cGMP (1 µmol/L) and reversed by protein kinase G (PKG) inhibitor Rp-8-CPT-cGMPS (100 µmol/L), thus implying the role of PKG and cGMP signaling in BBB function. Transcription factor JunD knockdown by small interfering RNA resulted in no change of permeability by CNP. In vivo study of mouse brain by fluorimetric analysis with intravenous administration of sodium fluorescein (40 mg/kg) also showed a significant increase in BBB permeability by CNP (10 nmol/kg, intravenously). These findings suggest that CNP modulates the BBB permeability by altering ZO-1 expression.

Clinical presentation and treatment of aneurysms associated with basilar artery fenestration.

Aneurysms associated with a fenestrated basilar artery are rare, and treatment strategies have yet to be established. A direct surgical approach to the basilar artery is challenging because the surrounding anatomy is complex. We retrospectively compared the clinical features and treatment outcomes of eight patients (seven female, one male) with aneurysms associated with a fenestrated basilar artery after clipping or coil embolisation and reviewed the literature. Of the eight aneurysms, four were ruptured; seven aneurysms were located at the proximal part of the basilar artery and one aneurysm was located at the middle of the basilar artery. Six aneurysms were surgically treated. Four aneurysms were embolised with Guglielmi detachable coils, two aneurysms were clipped via the transcondylar or temporopolar approach, and two aneurysms were not treated. All six surgically treated patients had good outcomes. We found that both coil embolisation and direct clipping to treat aneurysms associated with a fenestrated basilar artery have advantages and disadvantages. To obtain favourable outcomes, the selected treatment modality must consider the patient's age and clinical condition, the aneurysm size and shape, the direction of the dome, the relationship with perforators, and the neurosurgeon's expertise.

Accuracy and pitfalls of multidetector-row computed tomography in detecting spinal dural arteriovenous fistulas.

OBJECT: The purpose of this study was to evaluate the accuracy of multidetector-row CT angiography (MDCTA) in demonstrating spinal dural arteriovenous fistulas (SDAVFs). METHODS: The authors studied 10 patients with SDAVFs, including 2 with spinal epidural AVFs, who underwent preoperative MR imaging, MDCTA, and digital subtraction angiography (DSA). In the evaluation of coronal sections of multiplanar reformation MDCTA images, inspection was focused on the presence of the following findings: 1) dilated perimedullary veins in the spinal canal; 2) focal enhancement of the nerve root, suggesting the location of the AVF, around the dural sleeve; and 3) a radicular vein that drains the AVF into perimedullary veins. The utility of MDCTA was assessed by comparing its findings with those of DSA in each case. RESULTS: Digital subtraction angiography confirmed that the AVFs were located in the thoracic spine in 4 patients and in the lumbar spine in 6 patients, and MDCTA detected dilated perimedullary veins in all 10 patients. In 8 patients, there was focal enhancement of the nerve root. The radicular vein that drains the AVF into the perimedullary veins was found in 8 cases. In 8 cases, the MDCTA-derived level and side of the AVF and its feeder corresponded with those shown by DSA. In 2 patients, however, the MDCTA-derived side of the feeder was on the side contralateral to the feeding artery confirmed by DSA. These lesions were interpreted as spinal epidural AVFs with perimedullary drainage. In 2 cases, MDCTA could not detect the multiplicity of their feeders. CONCLUSIONS: The use of MDCTA preceding DSA can be helpful to focus the selective catheter angiography on certain spinal levels. However, one should keep in mind that epidural AVFs with perimedullary drainage may resemble SDAVFs and also that MDCTA cannot exclude the possibility of multiple feeders. Further research should elucidate how broadly selective angiography should explore around the MDCTA-suggested target.

Use of a guide wire system to insert guiding catheters.

In patients with severe arteriosclerosis or anatomical variations such as a bovine arch, the insertion of a guiding catheter for carotid artery stenting is difficult. The authors use a guide wire system as an anchor and advance the guiding catheter to an area proximal to the stenotic structure. This method is useful and safer than others for carotid artery stenting.

Multi-detector-row CT angiography as a preoperative evaluation for spinal arteriovenous fistulae.

The role of multi-detector-row computed tomographic angiography (MDCTA) in spinal vascular malformations has not yet been determined. We present a report on a short series of spinal arteriovenous fistulae (AVF) evaluated by MDCTA. With 4-row and 16-row MDCTA, three cases of spinal dural AVF and one case of perimedullary AVF were examined. Each case was also examined by magnetic resonance (MR) imaging and spinal catheter angiography. In two patients with spinal dural AVF, including one patient with angiographically occult AVF, MDCTA successfully located the site of the AVF in a multi-planar reformation image. MDCTA failed to locate the remaining case of spinal dural AVF, probably due to the small amount of shunting blood volume at the fistula. In a patient with perimedullary AVF, MDCTA visualized the broad range of the lesion, including the anterior spinal artery as a single feeder, the fistulous point, and the single perimedullary draining vein. In conclusion, although conventional spinal angiography might be still essential, MDCTA provides useful information for the surgeon in treatment of the spinal dural AVF. Further accumulation of clinical cases is required to determine the potential of MDCTA for perimedullary AVF. MDCTA should be considered as a choice of investigation in the evaluation of spinal AVFs.

Two caspase-2 transcripts are expressed in rat hippocampus after global cerebral ischemia.

Caspase family genes play a critical role in the initiation and execution of programmed cell death. Programmed cell death is an important contributor to neuronal loss following cerebral ischemia. We have performed a series of experiments to investigate the role of a specific caspase, caspase-2, in the development of delayed neuronal death following transient global ischemia in the rat. A rat ischemic brain cDNA library was screened, and two splice-variants of caspase-2 mRNA were identified, caspase-2S and caspase-2L, which were highly homologous with the sequences of human and mouse caspase-2S and caspase-2L genes, respectively. RT-PCR demonstrated an increase in expression of both caspase-2S and caspase-2L mRNA at 8, 24 and 72 h of reperfusion after global ischemia. The ratio of the two PCR fragments did not change significantly throughout the time course of reperfusion. Western blot with monoclonal antibody specific to the pro-apoptotic caspase-2L splice variant revealed an increase in procaspase-2 (51 kDa) protein from 4 to 72 h following ischemia compared with sham-operated controls. Furthermore, an approximately 30-kDa cleavage product appeared at 8 h and increased with increasing duration of reperfusion. Thus, caspase-2L is both translated and activated following transient global ischemia. Finally, intraventricular administration of the caspase-2-like inhibitor (VDVAD-FMK) 30 min before induction of ischemia decreased the number of CA1 neurons staining positively for DNA damage (Klenow-labeling assay) and increased the number of healthy-appearing CA1 neurons (cresyl violet) compared with vehicle-treated controls. Taken together, the data suggest that caspase-2 induction and activation are important mediators of delayed neuronal death following transient global ischemia.