Structure and magnetic properties of mono- and bi-layer graphene films on ultraprecision figured 4H-SiC(0001) surfaces.

Monolayer and bilayer graphene films with a few hundred nm domain size were grown on ultraprecision figured 4H-SiC(0001) on-axis and 8 degrees -off surfaces by annealing in ultra-high vacuum. Using X-ray photoelectron spectroscopy (XPS), atomic force microscopy, reflection high-energy electron diffraction, low-energy electron diffraction (LEED), Raman spectroscopy, and scanning tunneling microscopy, we investigated the structure, number of graphene layers, and chemical bonding of the graphene surfaces. Moreover, the magnetic property of the monolayer graphene was studied using in-situ surface magneto-optic Kerr effect at 40 K. LEED spots intensity distribution and XPS spectra for monolayer and bilayer graphene films could become an obvious and accurate fingerprint for the determination of graphene film thickness on SiC surface.

A case of giant common carotid artery aneurysm associated with vascular Behçet disease: successfully treated with a covered stent.

BACKGROUND: A carotid artery aneurysm associated with vascular Behçet disease is extremely rare and often difficult to treat. In this article, we explore a definitive therapeutic strategy for pseudoaneurysm with vascular Behçet disease. CASE DESCRIPTION: A 56-year-old man presented with swelling and a pulsatile subcutaneous mass of the left neck over a 6-month period. The diagnosis of vascular Behçet disease had already been established from the history of right subclavian artery aneurysm, oral ulcerations, and inflammatory skin lesions. Radiologic examination revealed a giant left CCA aneurysm (6.5 x 5.5 cm) with partial thrombosis. Another asymptomatic aneurysm was found in the right ICA. Because mass effects due to aneurysmal rupture and growth rapidly progressed, we decided on radical treatment. The endovascular reconstruction of the carotid artery was selected instead of direct surgery because of skin and connective tissue disorders at the regional site. A covered stent (8 x 60 mm, Passager, Boston Scientific, Fremont, CA) was placed from the CCA to the ICA, covering the whole aneurysmal portion. Postoperatively, the cervical mass remarkably reduced in size, and the patient's symptoms dramatically improved. The left carotid artery was patent at 12-month follow-up. CONCLUSIONS: A covered stent is very useful in repairing arteries with pseudoaneurysm, particularly in cases unsuitable for direct surgery with parent artery occlusion. The influence of the foreign body at the inflammatory lesion and long-term patency of covered stents should be discussed.

Contralateral meningeal artery supply of paramedian meningiomas.

BACKGROUND: When resecting at falcine or parasagittal portion of paramedian meningiomas, intraoperative hemostasis often is difficult despite effective management of ipsilateral meningeal arteries. We attribute such difficulties to meningeal artery blood supply from the contralateral side. We retrospectively studied feeding arteries from both sides in case of paramedian meningioma in terms of patient and tumor characteristics. METHODS: Forty-three patients with paramedian meningiomas underwent selective internal and external carotid angiography. We investigated how contralateral meningeal arterial feeders related to patient profiles and imaging, histopathologic, and immunohistochemical findings. RESULTS: Contralateral meningeal supply existed for 14 of 25 falcine meningiomas and 6 of 18 parasagittal meningiomas. Patients with contralateral feeders were 8.5 years younger than the others (P=.027) and were more likely to have larger tumors (P=.028). These were histopathologically malignant (P=.048), while showing more proliferation followed by monoclonal antibody against the Ki-67 antigen index (P=.012) and angiogenetic potential associated with vascular endothelial growth factor expression (P=.0085). CONCLUSIONS: Contralateral meningeal supply may reflect strong angiogenetic recruitment from rapid tumor growth followed by high expression of vascular endothelial growth factor. This angiographical feature may predict the aggressive growth of paramedian meningiomas.

De novo cerebral aneurysms manifesting as repeated subarachnoid hemorrhage and cerebral ischemic stroke--case report.

A 29-year-old man suffered repeated subarachnoid hemorrhage and cerebral ischemic stroke over a period of 6 years. Cerebral angiography at each episode disclosed development of multiple de novo aneurysms at the bilateral middle cerebral arteries (MCAs), internal carotid arteries, right anterior cerebral artery, and right vertebral artery. Two of the ruptured aneurysms were treated by surgical and endovascular treatment, but he died of the effects of rupture of a de novo right MCA aneurysm. Histological examination at autopsy disclosed marked degenerative changes in all layers of the cerebral vessels, which were probably congenital in origin.

Risk of aneurysmal rupture: the importance of neck orifice positioning-assessment using computational flow simulation.

OBJECTIVE: The aim of the present study was to clarify the risk of rupture in terminal-type intracranial aneurysms using computational flow simulation analysis. METHODS: First, idealized three-dimensional aneurysmal models were built from a solid voxel on the computer. We focused on round terminal-type aneurysms with the positioning of the neck orifice set according to the following three patterns in relationship to the axis of the parent artery: the Type-A neck orifice was positioned directly in line with the flow of the parent artery; the Type-B neck orifice was shifted 1.5 mm offline toward the unilateral branch; and the Type-C neck orifice was shifted 3 mm offline. Computational flow simulations were applied with Fujitsu alpha-Flow software (Fujitusu, Tokyo, Japan). We analyzed flow patterns using modified patient-specific models. We also investigated actual clinical situations to evaluate the differences in neck-orifice positioning between 20 ruptured aneurysms and 26 unruptured ones using three-dimensional angiograms. RESULTS: The Type-A neck orifice showed completely symmetrical stream lines in the aneurysm, whereas the Type-C orifice showed a clear round circulation. The Type-B neck orifice, on the other hand, exhibited intra-aneurysmal flow separation. The clinical research demonstrated that Type-B aneurysms were more likely to be found in the ruptured group (P < 0.05). CONCLUSION: Flow separation, recognized as one of the causes of intimal injury, could be observed only in Type-B aneurysms, a result that corresponded well with our clinical experience. From the flow-dynamics point of view, this positioning of the neck orifice may be one of the risk factors most likely to induce the rupture of unruptured aneurysms.

Thrombophilic abnormalities among patients with cranial dural arteriovenous fistulas.

OBJECTIVE: Dural sinus thrombosis often accompanies or precedes the development of dural arteriovenous fistulas (DAVFs). Because thrombophilic abnormalities can contribute to sinus thrombosis, we investigated the prevalence of such abnormalities and of venous sinus thrombosis in patients with DAVFs. METHODS: Thrombophilic factors were measured in 18 patients with DAVFs treated with embolization at our university hospital. Control data were obtained from patients with unruptured intracranial aneurysms. In addition to sinus occlusion, we investigated prothrombin time, activated thromboplastin time, platelet count, and fibrinogen, platelet, antithrombin III, protein C, protein S, anticardiolipin antibody, anti-cardiolipin beta2-glycoprotein-I complex antibody, and D-dimer levels. RESULTS: Of the 18 patients with DAVFs, 16 had abnormal D-dimer levels, whereas the mean values for other thrombophilic factors were nearly normal. D-dimer levels were significantly higher in preoperative DAVF patients than in controls. Interestingly, the mean value of D-dimer was higher in patients with sinus occlusion than in those without it (3.33 versus 1.19). D-dimer levels rose after embolization in eight out of 10 serially tested patients, but, on average, the change was not significant. In clinically cured patients treated more than 3 months before, D-dimer was lower than in preoperative patients. CONCLUSION: D-dimer is a very sensitive indicator of acute venous thrombosis, suggesting that elevations in patients with DAVFs are likely to reflect sinus thrombosis. D-dimer values decreased and nearly normalized in clinically cured patients during a long-term follow-up period, a finding consistent with completion of thrombosis and cure of the disease. To clarify the correlation between DAVF and sinus thrombosis from the aspect of etiology, we should thoroughly check the variation in the concentration of the thrombophilic factors in the patient with chronic sinus occlusion to know the variation in the fistula formation in the further study.