Hidetoshi Kasuya

Molecular cloning of a novel brain-type Na(+)-dependent inorganic phosphate cotransporter.

Abstract: We have isolated a human cDNA encoding a protein, designated DNPI, that shows 82% amino acid identity and 92% similarity to the human brain‐specific Na+‐dependent inorganic phosphate (Na+/Pi) cotransporter (BNPI), which is localized exclusively to neuron‐rich regions. Expression of DNPI mRNA in Xenopus oocytes resulted in a significant increase in Na+‐dependent Pi transport, indicating that DNPI is a novel Na+/Pi cotransporter. Northern blot analysis shows that DNPI mRNA is expressed predominantly in brain, where the highest levels are observed in medulla, substantia nigra, subthalamic nucleus, and thalamus, all of which express BNPI mRNA at low levels. In contrast, DNPI mRNA is expressed at low levels in cerebellum and hippocampus, where BNPI mRNA is expressed at high levels. No hybridizing signal for DNPI mRNA is observed in the glia‐rich region of corpus callosum. In other regions examined, both mRNAs are moderately or highly expressed. These results indicate that BNPI and DNPI, which coordinate Na+‐dependent Pi transport in the neuron‐rich regions of the brain, may form a new class within the Na+/Pi cotransporter family.

Genome-wide association study of intracranial aneurysm identifies three new risk loci

Saccular intracranial aneurysms are balloon-like dilations of the intracranial arterial wall; their hemorrhage commonly results in severe neurologic impairment and death. We report a second genome-wide association study with discovery and replication cohorts from Europe and Japan comprising 5,891 cases and 14,181 controls with ∼832,000 genotyped and imputed SNPs across discovery cohorts. We identified three new loci showing strong evidence for association with intracranial aneurysms in the combined dataset, including intervals near RBBP8 on 18q11.2 (odds ratio (OR) = 1.22, P = 1.1 × 10−12), STARD13-KL on 13q13.1 (OR = 1.20, P = 2.5 × 10−9) and a gene-rich region on 10q24.32 (OR = 1.29, P = 1.2 × 10−9). We also confirmed prior associations near SOX17 (8q11.23–q12.1; OR = 1.28, P = 1.3 × 10−12) and CDKN2A-CDKN2B (9p21.3; OR = 1.31, P = 1.5 × 10−22). It is noteworthy that several putative risk genes play a role in cell-cycle progression, potentially affecting the proliferation and senescence of progenitor-cell populations that are responsible for vascular formation and repair.

Susceptibility loci for intracranial aneurysm in European and Japanese populations

Stroke is the worlds third leading cause of death. One cause of stroke, intracranial aneurysm, affects ∼2% of the population and accounts for 500,000 hemorrhagic strokes annually in mid-life (median age 50), most often resulting in death or severe neurological impairment. The pathogenesis of intracranial aneurysm is unknown, and because catastrophic hemorrhage is commonly the first sign of disease, early identification is essential. We carried out a multistage genome-wide association study (GWAS) of Finnish, Dutch and Japanese cohorts including over 2,100 intracranial aneurysm cases and 8,000 controls. Genome-wide genotyping of the European cohorts and replication studies in the Japanese cohort identified common SNPs on chromosomes 2q, 8q and 9p that show significant association with intracranial aneurysm with odds ratios 1.24–1.36. The loci on 2q and 8q are new, whereas the 9p locus was previously found to be associated with arterial diseases, including intracranial aneurysm. Associated SNPs on 8q likely act via SOX17, which is required for formation and maintenance of endothelial cells, suggesting a role in development and repair of the vasculature; CDKN2A at 9p may have a similar role. These findings have implications for the pathophysiology, diagnosis and therapy of intracranial aneurysm.

Genomewide-Linkage and Haplotype-Association Studies Map Intracranial Aneurysm to Chromosome 7q11

Rupture of intracranial aneurysms (IAs) causes subarachnoid hemorrhage, a devastating condition with high morbidity and mortality. Angiographic and autopsy studies show that IA is a common disorder, with a prevalence of 3%-6%. Although IA has a substantial genetic component, little attention has been given to the genetic determinants. We report here a genomewide linkage study of IA in 104 Japanese affected sib pairs in which positive evidence of linkage on chromosomes 5q22-31 (maximum LOD score [MLS] 2.24), 7q11 (MLS 3.22), and 14q22 (MLS 2.31) were found. The best evidence of linkage is detected at D7S2472, in the vicinity of the elastin gene (ELN), a candidate gene for IA. Fourteen distinct single-nucleotide polymorphisms (SNPs) were identified in ELN, and no obvious allelic association between IA and each SNP was observed. The haplotype between the intron-20/intron-23 polymorphism of ELN is strongly associated with IA (P=3.81x10-6), and homozygous patients are at high risk (P=.002), with an odds ratio of 4.39. These findings suggest that a genetic locus for IA lies within or close to the ELN locus on chromosome 7.

Effect of Nicardipine Prolonged-Release Implants on Cerebral Vasospasm and Clinical Outcome After Severe Aneurysmal Subarachnoid Hemorrhage A Prospective, Randomized, Double-Blind Phase IIa Study

Background and Purpose— The purpose of this study was to investigate the effect of nicardipine prolonged-release implants (NPRIs) on cerebral vasospasm and clinical outcome after severe subarachnoid hemorrhage. Methods— Thirty-two patients with severe subarachnoid hemorrhage and undergoing aneurysm clipping were included into this single center, randomized, double-blind trial. Sixteen patients received NPRIs implanted into the basal cisterns in direct contact to the exposed proximal blood vessels; in 16 control patients, the basal cisterns were opened and washed out only without leaving implants. Angiography was performed preoperatively and at day 8±1. Computed tomography imaging was analyzed for the incidence of territorial infarcts unrelated to surgery. Patient outcome was assessed using the modified Rankin and National Institute of Health Stroke scales. Results— The incidence of angiographic vasospasm in proximal vessel segments was significantly reduced after implantation of NPRIs (73% control versus 7% NPRIs). Significant differences occurred also for the majority of distal vessel segments. Computed tomography scans revealed a lower incidence of delayed ischemic lesions (47% control versus 14% NPRIs). The NPRI group demonstrated more favorable modified Rankin and National Institute of Health Stroke scales as well as a significantly lower incidence of deaths (38% control versus 6% NPRIs). Conclusions— Implantation of NPRIs reduces the incidence of cerebral vasospasm and delayed ischemic deficits and improves clinical outcome after severe subarachnoid hemorrhage.

Application of Nicardipine Prolonged-release Implants: Analysis of 97 Consecutive Patients with Acute Subarachnoid Hemorrhage

To the Editor: We read with great interest the article by Kasuya et al. (2) on the application of nicardipine prolonged-release implants for subarachnoid hemorrhage. They analyzed 97 consecutive patients and compared 69 treated patients with 28 untreated patients. The authors concluded that application of local nicardipine prolonged-release implants leads to a reduced incidence of a delayed ischemic neurological deficit. Although the rate of clinical vasospasm could be roughly reduced by 50%, we would have expected a more marked effect for a therapy with the potential of adding a new dimension to the current strategy of prevention and treatment of cerebral vasospasm. However, some shortcomings of the currently reported methodology and the study design still leave hope that local intrathecal therapy of cerebral vasospasm can become a significant step forward. This prospective nonrandomized Phase II-type study resulted in a comparison between two inhomogeneous patient groups concerning the known risk factors of cerebral vasospasm. The control group without local pharmacological treatment consisted of 16 Fisher Grade 2 patients, nine Fisher Grade 3 patients, and three Fisher Grade 4 patients. Therefore, the natural risk for vasospasm differed between the pharmacologically treated group with a great majority of Fisher Grade 3 patients and the control group with predominant Fisher Grades of 2 and 4 and, therefore, a lower risk of vasospasm (1, 4). Besides, it is important to emphasize, that an incidence of clinical vasospasm of 11% in the untreated group and 6% in the medical group seems unusually low for a patient group dominated by Fisher Grade 3 hemorrhages. The current report leaves some open questions with regard to pharmacokinetics and effectiveness of the clinical set-up. The patients received from 2 to 12 pellets, resulting in different dosages. There was no correlation done between the quantity of nicardipine and the incidence of vasospasm. Only a positive local effect as documented by angiography was available as control. There was no monitoring of cerebrospinal fluid (CSF) levels of nicardipine. It seems unlikely that the released nicardipine could be sequestrated within the local cistern by the surrounding blood clots. In an animal study done on dogs, Pradilla et al. (3) documented an excellent diffusion of Evans blue dye from controlledrelease polymers throughout the subarachnoid space after experimental hemorrhage. In summary, we believe in the potential benefit of local therapy as a major step ahead in the treatment of vasospasm. Nicardipine may not be the optimum agent, or the dosing must be optimized. Perhaps a cocktail of several agents achieves a superior effect.

The unruptured intracranial aneurysm treatment score A multidisciplinary consensus

Objective: We endeavored to develop an unruptured intracranial aneurysm (UIA) treatment score (UIATS) model that includes and quantifies key factors involved in clinical decision-making in the management of UIAs and to assess agreement for this model among specialists in UIA management and research. Methods: An international multidisciplinary (neurosurgery, neuroradiology, neurology, clinical epidemiology) group of 69 specialists was convened to develop and validate the UIATS model using a Delphi consensus. For internal (39 panel members involved in identification of relevant features) and external validation (30 independent external reviewers), 30 selected UIA cases were used to analyze agreement with UIATS management recommendations based on a 5-point Likert scale (5 indicating strong agreement). Interrater agreement (IRA) was assessed with standardized coefficients of dispersion (vr*) (vr* = 0 indicating excellent agreement and vr* = 1 indicating poor agreement). Results: The UIATS accounts for 29 key factors in UIA management. Agreement with UIATS (mean Likert scores) was 4.2 (95% confidence interval [CI] 4.1–4.3) per reviewer for both reviewer cohorts; agreement per case was 4.3 (95% CI 4.1–4.4) for panel members and 4.5 (95% CI 4.3–4.6) for external reviewers (p = 0.017). Mean Likert scores were 4.2 (95% CI 4.1–4.3) for interventional reviewers (n = 56) and 4.1 (95% CI 3.9–4.4) for noninterventional reviewers (n = 12) (p = 0.290). Overall IRA (vr*) for both cohorts was 0.026 (95% CI 0.019–0.033). Conclusions: This novel UIA decision guidance study captures an excellent consensus among highly informed individuals on UIA management, irrespective of their underlying specialty. Clinicians can use the UIATS as a comprehensive mechanism for indicating how a large group of specialists might manage an individual patient with a UIA.

The effect of continuous drainage of cerebrospinal fluid in patients with subarachnoid hemorrhage: a retrospective analysis of 108 patients.

The effects of continuous drainage of cerebrospinal fluid (CSF) on vasospasm and hydrocephalus were analyzed retrospectively in 108 patients with subarachnoid hemorrhage (SAH) who were operated on for ruptured aneurysms within 48 hours of their onset. Ninety-two of these patients underwent a procedu

Efficacy and Safety of Nicardipine Prolonged-Release Implants for Preventing Vasospasm in Humans

Background and Purpose— Despite extensive investigative efforts, there are few treatments that can prevent vasospasm after subarachnoid hemorrhage. This study was conducted to examine the efficacy and safety of nicardipine prolonged-release implants (NPRI) for humans, which have already been proven in dogs. Methods— Twenty consecutive subarachnoid hemorrhage patients with thick subarachnoid clot were treated with NPRI (a pellet of diameter 2 mm, length 10 mm, containing 4 mg of nicardipine) during surgery after clipping of their aneurysm. The number and location of pellets depended on the amount and site of subarachnoid clot on preoperative CT and on craniotomy. Results— Two to 10 pellets were implanted in the cistern of the internal carotid, middle cerebral, and/or anterior cerebral artery, where thick clots existed and therefore vasospasm related to delayed ischemic neurological deficits was highly likely. Delayed ischemic neurological deficits and cerebral infarctions were seen in 1 patient. Angiography performed on days 7 to 12 revealed no vasospasm in any arteries near which NPRI were placed. No complications were experienced. Conclusions— Vasospasm was completely prevented for the arteries in thick clot cisterns, when NPRI were placed adjacent to the arteries during surgery. This drug-delivery system offers a promising approach for preventing vasospasm.

Common variant near the endothelin receptor type A (EDNRA) gene is associated with intracranial aneurysm risk

The pathogenesis of intracranial aneurysm (IA) formation and rupture is complex, with significant contribution from genetic factors. We previously reported genome-wide association studies based on European discovery and Japanese replication cohorts of 5,891 cases and 14,181 controls that identified five disease-related loci. These studies were based on testing replication of genomic regions that contained SNPs with posterior probability of association (PPA) greater than 0.5 in the discovery cohort. To identify additional IA risk loci, we pursued 14 loci with PPAs in the discovery cohort between 0.1 and 0.5. Twenty-five SNPs from these loci were genotyped using two independent Japanese cohorts, and the results from discovery and replication cohorts were combined by meta-analysis. The results demonstrated significant association of IA with rs6841581 on chromosome 4q31.23, immediately 5′ of the endothelin receptor type A with P = 2.2 × 10−8 [odds ratio (OR) = 1.22, PPA = 0.986]. We also observed substantially increased evidence of association for two other regions on chromosomes 12q22 (OR = 1.16, P = 1.1 × 10−7, PPA = 0.934) and 20p12.1 (OR = 1.20, P = 6.9 × 10−7, PPA = 0.728). Although endothelin signaling has been hypothesized to play a role in various cardiovascular disorders for over two decades, our results are unique in providing genetic evidence for a significant association with IA and suggest that manipulation of the endothelin pathway may have important implications for the prevention and treatment of IA.