Cerebral edema contributes significantly to morbidity and death associated with many common neurological disorders. However, current treatment options are limited to hyperosmolar agents and surgical decompression, therapies introduced more than 70 years ago. Here we show that mice deficient in aquaporin-4 (AQP4), a glial membrane water channel, have much better survival than wild-type mice in a model of brain edema caused by acute water intoxication. Brain tissue water content and swelling of pericapillary astrocytic foot processes in AQP4-deficient mice were significantly reduced. In another model of brain edema, focal ischemic stroke produced by middle cerebral artery occlusion, AQP4-deficient mice had improved neurological outcome. Cerebral edema, as measured by percentage of hemispheric enlargement at 24 h, was decreased by 35% in AQP4-deficient mice. These results implicate a key role for AQP4 in modulating brain water transport, and suggest that AQP4 inhibition may provide a new therapeutic option for reducing brain edema in a wide variety of cerebral disorders.

Moyamoya disease (MMD) shows progressive cerebral angiopathy characterized by bilateral internal carotid artery stenosis and abnormal collateral vessels. Although B15% of MMD cases are familial, the MMD gene(s) remain unknown. A genome-wide association study of 785 720 single-nucleotide polymorphisms (SNPs) was performed, comparing 72 Japanese MMD patients with 45 Japanese controls and resulting in a strong association of chromosome 17q25-ter with MMD risk. This result was further confirmed by a locus-specific association study using 335 SNPs in the 17q25-ter region. A single haplotype consisting of seven SNPs at the RNF213 locus was tightly associated with MMD (P¼5.3Â10 À10 ). RNF213 encodes a really interesting new gene finger protein with an AAA ATPase domain and is abundantly expressed in spleen and leukocytes. An RNA in situ hybridization analysis of mouse tissues indicated that mature lymphocytes express higher levels of Rnf213 mRNA than their immature counterparts. Mutational analysis of RNF213 revealed a founder mutation, p.R4859K, in 95% of MMD families, 73% of non-familial MMD cases and 1.4% of controls; this mutation greatly increases the risk of MMD (P¼1.2Â10 À43 , odds ratio¼190.8, 95% confidence interval¼71.7-507.9). Three additional missense mutations were identified in the p.R4859K-negative patients. These results indicate that RNF213 is the first identified susceptibility gene for MMD.

Oxidative stress generated during stroke is a critical event leading to blood-brain barrier (BBB) disruption with secondary vasogenic edema and hemorrhagic transformation of infarcted brain tissue, restricting the benefit of thrombolytic reperfusion. In this study, the authors demonstrate that ischemia-reperfusion-induced BBB disruption in mice deficient in copper/zinc-superoxide dismutase (SOD1) was reduced by 88% ( P < 0.0001) and 73% ( P < 0.01), respectively, after 3 and 7 hours of reperfusion occurring after 1 hour of ischemia by the inhibition of matrix metalloproteinases. Accordingly, the authors show that local metalloproteinase-generated proteolytic imbalance is more intense in ischemic regions of SOD1 mice than in wild-type litter mates. Moreover, active in situ proteolysis is, for the first time, demonstrated in ischemic leaking capillaries that produce reactive oxygen species. By showing that oxidative stress mediates BBB disruption through metalloproteinase activation in experimental ischemic stroke, this study provides a new target for future therapeutic strategies to prevent BBB disruption and potentially reperfusion-triggered intracerebral hemorrhage.

Background and Purpose-The objectives of the present study were to estimate an annual number of patients with moyamoya disease in Japan and to describe the clinicoepidemiological features of the disease. Methods-The study consisted of 2 questionnaire surveys, which were distributed to randomly selected departments of neurosurgery, internal medicine, neurology, cerebrovascular medicine, and pediatrics in hospitals throughout Japan. The first survey inquired about the number of the patients treated in 2003, and the second requested additional detailed clinicoepidemiological information about each patient identified in the first survey.

Background and Purpose-About one half of those who develop adult-onset moyamoya disease experience intracranial hemorrhage. Despite the extremely high frequency of rebleeding attacks and poor prognosis, measures to prevent rebleeding have not been established. The purpose of this study is to determine whether extracranial-intracranial bypass can reduce incidence of rebleeding and improve patient prognosis. Methods-This study was a multicentered, prospective, randomized, controlled trial conducted by 22 institutes in Japan.Adult patients with moyamoya disease who had experienced intracranial hemorrhage within the preceding year were given either conservative care or bilateral extracranial-intracranial direct bypass and were observed for 5 years. Primary and secondary end points were defined as all adverse events and rebleeding attacks, respectively. Results-Eighty patients were enrolled (surgical, 42; nonsurgical, 38). Adverse events causing significant morbidity were observed in 6 patients in the surgical group (14.3%) and 13 patients in the nonsurgical group (34.2%). Kaplan-Meier survival analysis revealed significant differences between the 2 groups (3.2%/y versus 8.2%/y; P=0.048). The hazard ratio of the surgical group calculated by Cox regression analysis was 0.391 (95% confidence interval, 0.148-1.029).Rebleeding attacks were observed in 5 patients in the surgical group (11.9%) and 12 in the nonsurgical group (31.6%), significantly different in the Kaplan-Meier survival analysis (2.7%/y versus 7.6%/y; P=0.042). The hazard ratio of the surgical group was 0.355 (95% confidence interval, 0.125-1.009). Conclusions-Although statistically marginal, Kaplan-Meier analysis revealed the significant difference between surgical and nonsurgical group, suggesting the preventive effect of direct bypass against rebleeding. Clinical Trial Registration

Summary: During cerebral ischemia blood-brain barrier (BBB) disruption is a critical event leading to vasogenic edema and secondary brain injury. Gelatinases A and B are matrix metalloproteinases (MMP) able to open the BBB, The current study analyzes by zymography the early gelatinases expression and activation during permanent ischemia in mice (n = 15).ProMMP-9 expression was significantly (P < 0.001) increased in ischemic regions compared with corresponding contralateral regions after '1 hours of ischemia (mean 694.7 arbitrary units[AU], SD ± 238.4 versus mean 107.6 AU, SD ± 15.6) and remained elevated until 24 hours (mean 745,7 AU, SD ± 157.4). Moreover, activated MMP-9 was observed 4 hours after the initiation of ischemia. At the same time as the appearance Blood-brain barrier (BBB) integrity protects the neu ronal microenvironment (Cserr and Bundgaard, 1986). When this integrity is lost, inflammatory cells and fluid penetrate the brain, causing edema and cell death (Fish man, 1975), Impermeability of the BBB is maintained by microvascular endothelial cells through their tight junc tions (Siflinger-Birnboim et aI., 1987) and basal lamina. The latter is composed of type IV collagen, fibronectin, Received October 20, 1998; final revision received January 19, 1999; accepted January 20, 1999. Supported by National Institutes of Health grants NS 25372, NS 14543, NS 36147 and NOI NS 82386. Y. Gasche is a research fellow supported by the Geneva University Hospital Fund. P.H. Chan is a recipient of the Jacob Javits Neuroscience Investigator Award.Address correspondence and reprint requests to Dr. Pak H. Chan, Neurosurgical Laboratories, Stanford University, 701B Welch Road, Room 148, Palo Alto, CA 94304, U.S.A.Abbreviations used: BBB, blood-brain barrier; EDTA, ethylenedi amine tetraacetic acid; MMP, metalloproteinase; MMP-2, gelatinase A; MMP-9, gelatinase B; PBS, phosphate-buffered saline; pMCAO, per manent middle cerebral artery occlusion; ROS, reactive oxygen spe cies; SDS, sodium dodecyl sulfate; TIMP, tissue inhibitor of metallo proteinase; tMCAO, transient middle cerebral artery occlusion; TNCA, Tris HCI-NaCI-CaCI2• 1020 of activated MMP-9, we detected by the Evan's blue extrava sation method a clear increase of BBB permeability, Tissue inhibitor of metalloproteinase-1 was not modified during per manent ischemia at any time. The ProMMP-2 was significantly (P < 0.05) increased only after 24 hours of permanent ischemia (mean 213.2 AU, SD ± 60.6 versus mean 94.6 AU, SD ± 13.3), and no activated form was observed. The appearance of acti vated MMP-9 after 4 hours of ischemia in correlation with BBB permeability alterations suggests that MMP-9 may play an active role in early vasogenic edema development after stroke.

Release of cytochrome c from mitochondria to the cytosol is a critical step in apoptotic cell death after focal cerebral ischemia. The relationship among cytochrome c release, selective vulnerability, and delayed death of hippocampal CA1 neurons after transient global ischemia was examined. Global ischemia was induced by 10 min of bilateral common carotid artery occlusion and hypotension in rats. Cytosolic expression of cytochrome c was evaluated by immunohistochemistry and Western blotting. Apoptosis after global ischemia was also characterized by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling (TUNEL) staining and DNA gel electrophoresis. Immunohistochemistry showed cytosolic cytochrome c-positive cells exclusively in the CA1 subregion of the hippocampus as early as 2 hr after ischemia. Double fluorescent immunostaining confirmed that CA1 neurons and a small number of astrocytes expressed cytochrome c. Western blot analysis revealed a band (15 kDa) of cytochrome c in the cytosolic fraction and a corresponding decrease in the mitochondrial fraction. A significant number of TUNEL-positive cells appeared only in the CA1 pyramidal cell layer of the hippocampus, and DNA gel electrophoresis showed a significant amount of DNA fragmentation 3-5 d after ischemia. Our data provide the first evidence that cytochrome c was released to the cytosol from mitochondria in CA1 neurons after global ischemia and that the release preceded DNA fragmentation. These findings suggest cytochrome c involvement in the delayed death of hippocampal CA1 neurons in rats after transient global ischemia.

Recent in vitro cell-free studies have shown that cytochrome c release from mitochondria is a critical step in the apoptotic process. The present study examined the expression of cytochrome c protein after transient focal cerebral ischemia in rats, in which apoptosis was assumed to contribute to the expansion of the ischemic lesion. In situ labeling of DNA breaks in frozen sections after 90 minutes of middle cerebral artery (MCA) occlusion showed a significant number of striatal and cortical neurons, which were maximized at 24 hours after ischemia, exhibiting chromatin condensation, nuclear segmentation, and apoptotic bodies. Cytosolic localization of cytochrome c was detected immunohistochemically in the ischemic area as early as 4 hours after 90 minutes of MCA occlusion. Western blot analysis of the cytosolic fraction revealed a strong single 15-kDa band, characteristic of cytochrome c, only in the samples from the ischemic hemisphere. Western blot analysis of the mitochondrial fraction showed a significant amount of mitochondrial cytochrome c in nonischemic brain, which was decreased in ischemic brain 24 hours after ischemia. These results provide the first evidence that cytochrome c is being released from mitochondria to the cytosol after transient focal ischemia. Although further evaluation is necessary to elucidate its correlation with DNA fragmentation, our results suggest the possibility that cytochrome c release may play a role in DNA-damaged neuronal cell death after transient focal cerebral ischemia in rats.