Ken-ichiro Kikuta

Identification of RNF213 as a Susceptibility Gene for Moyamoya Disease and Its Possible Role in Vascular Development

Background Moyamoya disease is an idiopathic vascular disorder of intracranial arteries. Its susceptibility locus has been mapped to 17q25.3 in Japanese families, but the susceptibility gene is unknown. Methodology/Principal Findings Genome-wide linkage analysis in eight three-generation families with moyamoya disease revealed linkage to 17q25.3 (P<10-4). Fine mapping demonstrated a 1.5-Mb disease locus bounded by D17S1806 and rs2280147. We conducted exome analysis of the eight index cases in these families, with results filtered through Ng criteria. There was a variant of p.N321S in PCMTD1 and p.R4810K in RNF213 in the 1.5-Mb locus of the eight index cases. The p.N321S variant in PCMTD1 could not be confirmed by the Sanger method. Sequencing RNF213 in 42 index cases confirmed p.R4810K and revealed it to be the only unregistered variant. Genotyping 39 SNPs around RNF213 revealed a founder haplotype transmitted in 42 families. Sequencing the 260-kb region covering the founder haplotype in one index case did not show any coding variants except p.R4810K. A case-control study demonstrated strong association of p.R4810K with moyamoya disease in East Asian populations (251 cases and 707 controls) with an odds ratio of 111.8 (P = 10−119). Sequencing of RNF213 in East Asian cases revealed additional novel variants: p.D4863N, p.E4950D, p.A5021V, p.D5160E, and p.E5176G. Among Caucasian cases, variants p.N3962D, p.D4013N, p.R4062Q and p.P4608S were identified. RNF213 encodes a 591-kDa cytosolic protein that possesses two functional domains: a Walker motif and a RING finger domain. These exhibit ATPase and ubiquitin ligase activities. Although the mutant alleles (p.R4810K or p.D4013N in the RING domain) did not affect transcription levels or ubiquitination activity, knockdown of RNF213 in zebrafish caused irregular wall formation in trunk arteries and abnormal sprouting vessels. Conclusions/Significance We provide evidence suggesting, for the first time, the involvement of RNF213 in genetic susceptibility to moyamoya disease.

Risk factors for subsequent hemorrhage in patients with cerebral arteriovenous malformations

OBJECT The aim of this study was to identify the natural history of untreated cerebral arteriovenous malformations (AVMs) and the risk factors for subsequent hemorrhage after an initial AVM diagnosis. METHODS The authors studied 305 consecutive patients with AVMs at the Kyoto University Hospital between 1983 and 2005. These patients were followed up until the first subsequent hemorrhage, the start of any treatment, or the end of 2005. Possible risk factors that were investigated included age at initial diagnosis, sex, type of initial presentation, size and location of the AVM nidus, and the venous drainage pattern. Subsequent hemorrhage occurred in 26 patients from the hemorrhagic group during 380 patient-years, and in 16 patients from the nonhemorrhagic group during 512 patient-years. RESULTS The annual bleeding rate in the hemorrhagic group was 6.84% after the initial hemorrhage; however, that rate decreased in the first 5 years (15.42% in the first year, 5.32% in the subsequent 4 years, and 1.72% in more than 5 years). In the nonhemorrhagic group (annual bleeding rate of 3.12%), the patients initially presenting with headaches (annual bleeding rate of 6.48%) or asymptomatic presentations (annual bleeding rate of 6.44%) had a higher risk for subsequent hemorrhage. Conversely, those patients presenting with seizures (annual bleeding rate of 2.20%) or neurological deficits (annual bleeding rate of 1.73%) had a lower risk. A significantly increased risk (p < 0.05) of rebleeding was found among children (hazard ratio [HR] = 2.69), females (HR = 2.93), or patients with deep-seated AVMs (HR = 3.07). CONCLUSIONS Children, females, and patients with deep-seated AVMs had a threefold increased risk of rebleeding after an initial cerebral AVM. This increased risk was highest in the first year after the initial hemorrhage, and thereafter gradually decreased.

Inheritance pattern of familial moyamoya disease: autosomal dominant mode and genomic imprinting

Background: Although the aetiology of moyamoya disease (MMD) has not been fully clarified, genetic analysis of familial MMD (F-MMD) has considerable potential to disclose it. Objective: To determine the inheritance pattern and clinical characteristics of F-MMD to enable precise genetic analyses of the disease. Methods: 15 highly aggregated Japanese families (52 patients; 38 women and 14 men) with three or more affected members were examined. The difference in categories of age at onset (child onset, adult onset and asymptomatic) between paternal and maternal transmission was compared by χ2 statistics. Results: In all families there had been three or more generations without consanguinity, and all types of transmission, including father-to-son, were observed. Among a total of 135 offspring of affected people, 59 (43.7%) were patients with MMD or obligatory carriers. Affected mothers were more likely to produce late-onset (adult-onset or asymptomatic) female offspring (p = 0.007). Conclusions: The mode of inheritance of F-MMD is autosomal dominant with incomplete penetrance. Thus, in future genetic studies on F-MMD, parametric linkage analyses using large families with an autosomal dominant mode of inheritance are recommended. Genomic imprinting may be associated with the disease.

Milrinone for the treatment of cerebral vasospasm after subarachnoid hemorrhage: report of seven cases.

OBJECTIVEThe intra-arterial infusion of papaverine has been used for dilation of spastic cerebral vessels after aneurysmal subarachnoid hemorrhage, although its efficacy is controversial. Milrinone is an inotropic drug that dilates vessels by phosphodiesterase inhibition in a mechanism similar to that of papaverine. We examined the effects of intra-arterial and subsequent intravenous administration of milrinone on patients with symptomatic cerebral vasospasm. METHODSSeven patients with cerebral vasospasm were enrolled in this study. Milrinone was delivered intra-arterially via catheter at a rate of 0.25 mg/min. The total delivered dose was between 2.5 and 15 mg. Radiological measurement of the middle cerebral artery diameter and cerebral blood flow was carried out before and after arterial infusion. Intravenous treatment followed at 0.50 or 0.75 &mgr;g/kg/min for up to 2 weeks from the onset of subarachnoid hemorrhage. RESULTSDilation of the vasospastic vessels occurred in all patients. The rate of cerebral blood flow was calculated in six patients and was increased in all. Subsequent intravenous infusion was effective in preventing a recurrence of symptomatic vasospasm in four of the seven patients. CONCLUSIONIt is suggested that milrinone was effective and safe for the treatment of cerebral vasospasm after subarachnoid hemorrhage in the patients in this series. Intra-arterial infusion with adjunctive intravenous infusion holds promise as a clinically advantageous treatment regimen.

Detection of a residual nidus by surgical microscope-integrated intraoperative near-infrared indocyanine green videoangiography in a child with a cerebral arteriovenous malformation

With the use of indocyanine green (ICG) as a novel fluorescent dye, and its integration into a compact system that takes advantage of modern video technology, fluorescence angiography has recently reemerged as a viable option. In this report, the authors show the efficacy of ICG videoangiography in the case of a child with a cerebral arteriovenous malformation (AVM). In this case, the ICG videoangiography shows residual nidus of diffuse-type AVM. This is a safe and simple method that can be used to assess the microcirculation of the brain. The ICG videoangiography is helpful in resecting residual cerebral AVM, especially in cases of diffuse-type AVM.

A phase I/II clinical trial investigating the adverse and therapeutic effects of a postoperative autologous dendritic cell tumor vaccine in patients with malignant glioma

Previous clinical trials of dendritic cell (DC)-based immunotherapy in patients with glioblastoma multiforme (GBM) have reported induction of systemic immune responses and prolonged survival. From 2003 to 2005, we performed a clinical trial in which patients with malignant glioma underwent surgery for maximal cytoreduction followed by a 6-month 10-injection course of autologous DC-tumor vaccine therapy, each injection containing 1-6×10(7) DC. Of the 17 treated patients (16 with World Health Organization grade IV and one with grade III glioma), eight (47.1%) had an initial transient elevation in aspartate aminotransferase (AST)/alanine aminotransferase (ALT). Vaccination caused some tumor shrinkage and increased concentration of tumor-infiltrating CD8(+) lymphocytes. Median survival and 5-year survival were 525 days and 18.8%, respectively, for 16 patients with grade IV glioma (381 days and 12.5% for eight newly diagnosed; 966 days and 25% for eight relapsed patients) compared to 380 days and 0% for 63 historical control patients. We concluded that autologous DC-tumor immunotherapy benefits patients with malignant glioma but may cause transient but reversible elevation of serum AST/ALT levels.

High-Affinity Arginine Transport of Bovine Aortic Endothelial Cells Is Impaired by Lysophosphatidylcholine

The mechanisms of endothelial dysfunction characterized by the impaired nitric oxide (NO) release have not yet been clarified. Because the phenomenon is mimicked in vitro by the application of oxidized LDL and its major lipid constituent, lysophosphatidylcholine (LPC), we analyzed their effects on the arginine-NO system, especially on the arginine transport system. LPC inhibited NO release induced by ADP in cultured bovine aortic endothelial cells. The inhibition was attenuated by the excess amount of extracellular arginine. LPC was found to inhibit the arginine transport in bovine aortic endothelial cells, which is mediated by high- and low-affinity components. LPC predominantly impaired the high-affinity component. In the presence of a high concentration of arginine, LPC showed apparently no inhibition of arginine transport, because the low-affinity transporter compensated for the activity. Taken together, the impairment of the high-affinity transport system might account for the inhibition of NO release by LPC. LPC also inhibited arginine transport in the intima of intact bovine aorta. Furthermore, LPC inhibited the activity of the high-affinity arginine transporter in endothelial cells, in the cationic amino acid transporter-1 expressed in COS-7 cells. The activity of cationic amino acid transporter-1 might be important for the prevention of endothelial dysfunction.

Surgery of cerebral arteriovenous malformations.

Despite remarkable progress, the microsurgical extirpation of cerebral arteriovenous malformations (AVMs) even by experienced neurosurgeons is not always easy or safe. This article focuses on how to render AVM surgery safer, and offers strategies and tactics for avoiding perilous bleeding and preserving postoperative neurological function. Our treatment strategies and surgical techniques are offered from the operating surgeons perspective. An understanding of pathophysiology of cerebral AVMs is important for their appropriate surgical treatment. Sophisticated neuroimaging techniques and scrupulous neurophysiological examinations alert to possible complications, and improved surgical approaches help to minimize the sequelae of unanticipated complications. At the early stage of cerebral AVM surgery, extensive dissection of the sulci, fissures, and subarachnoid cistern should be performed to expose feeders, nidus, and drainers. Problems with the surgery of large and/or deep-seated lesions are exacerbated when arterial bleeding from the nidus continues even after all major feeders are thought to have been occluded. We routinely place catheters for angiography at the surgery of complex AVMs to find missing feeding arteries or to identify the real-time hemodynamic status of the lesion. Temporary clip application on feeders and less coagulation of the nidus is necessary to control intranidal pressure and to avoid uncontrollable bleeding from the nidus and adjacent brain. Intraoperative navigation images superimposed on tractography images can provide us with valuable information to minimize neurological deficits. Deeper insight into AVM nature and into events that occur during AVM surgery as well as the inclusion of molecular biological approaches will open new horizons for the safe and effective treatment of AVMs.

EFFECT OF EARLY OPTIC CANAL UNROOFING ON THE OUTCOME OF VISUAL FUNCTIONS IN SURGERY FOR MENINGIOMAS OF THE TUBERCULUM SELLAE AND PLANUM SPHENOIDALE

OBJECTIVEThe aim of this study was to evaluate the effect of early optic canal unroofing on visual function in patients with meningiomas of the tuberculum sellae and planum sphenoidale. METHODSWe retrospectively reviewed the clinical records of 20 consecutive patients with tuberculum sellae meningiomas and two patients with planum sphenoidale meningiomas who were admitted to our institution from 1999 to 2007. Factors that may influence postoperative visual functions were analyzed, including patients age and sex, duration of preoperative visual symptoms, preoperative visual acuity, tumor size, tumor consistency, tumor extension into the optic canal, tumor adhesion to the optic nerve, timing of optic canal unroofing, and tumor resection rate. RESULTSThe mean patient age was 52.9 ± 13.7 years (range, 27–73 yr); 18 patients were women and four were men. The mean maximum tumor size was 2.3 ± 0.7 cm (range, 1.5–3.5 cm). Visual symptoms were present preoperatively in 19 patients, and three patients were asymptomatic. The mean duration of visual symptoms was 12.0 ± 16.4 months (range, 0–72 mo). Tumor resection was evaluated according to Simpsons grade, and Grade II was achieved in 14, Grade III in two, and Grade IV in six (two patients were recurrent cases). Tumors were extended into the optic canal in 15 patients, and severe adhesion to the optic nerve was observed in nine patients. Tumor consistency was soft in eight patients, intermediate in eight patients, and hard in six patients. The optic canal was unroofed early before dissection or manipulation of tumor in nine patients (early group) and after dissection of tumor in seven patients (late group), and optic canal unroofing was not performed in six patients (none group; no canal extension in two and intentional incomplete resection in four patients). Visual symptoms were improved in 10 patients, unchanged in seven patients, and worsened in five patients (transient in two and permanent in three). Logistic regression analysis revealed that early optic canal unroofing was an independent factor for postoperative improvement of visual symptoms. CONCLUSIONEarly optic canal unroofing may increase the possibility of improved preoperative visual symptoms in surgical resection of tuberculum sellae meningiomas and planum sphenoidale meningiomas.

Diffusion tensor fiber tractography for arteriovenous malformations : Quantitative analyses to evaluate the corticospinal tract and optic radiation

BACKGROUND AND PURPOSE: We hypothesized that diffusion tensor fiber tractography would be affected by intracranial arteriovenous malformation (AVM). The purpose of the present study was to evaluate the influence of intracranial AVM on corticospinal tract and optic radiation tractography. MATERIALS AND METHODS: The subject group comprised 34 patients with untreated intracranial AVM. Hemorrhage was present in 13 patients and absent in 21 patients. Perinidal fractional anisotropy (FA) and number of voxels along the reconstructed corticospinal and optic radiation tracts were measured, and left-to-right asymmetry indices (AIs) for those values were quantified. Patients were assigned to 1 of 3 groups: tracts distant from nidus, tracts close to nidus without neurologic symptoms, and tracts close to nidus associated with neurologic symptoms. One-way analysis of variance was used to compare differences in AI between groups. Hemorrhagic and nonhemorrhagic groups were assessed separately. RESULTS: In patients without hemorrhage, AI of optic radiation volume (P < .0001), AI of perinidal FA along corticospinal tract (P = .006), and optic radiation (P = .01) differed significantly between groups. In patients associated with hemorrhage, AI of corticospinal tract volume (P = .01), AI of perinidal FA along corticospinal tract (P = .04), and optic radiation (P = .004) differed significantly between groups. CONCLUSIONS: Corticospinal tract and optic radiation tractography were visualized in patients with AVM. In patients with both hemorrhagic and nonhemorrhagic AVM, the 2 fiber tracts close to the nidus were less visualized in the affected hemisphere than those distant from the nidus. Tracts were less visualized in patients with neurologic symptoms than in asymptomatic patients.