The cerebral artery in cynomolgus monkeys (Macaca fascicularis).

Cerebral artery structure has not been extensively studied in primates. The aim of this study was to examine the cerebrovascular anatomy of cynomolgus monkeys (Macaca fascicularis), which are one of the most commonly used primates in medical research on human diseases, such as cerebral infarction and subarachnoid hemorrhage. In this study, we investigated the anatomy and diameter of cerebral arteries from 48 cynomolgus monkey brain specimens. We found three anatomical differences in the vascular structure of this species compared to that in humans. First, the distal anterior cerebral artery is single. Second, the pattern in which both the anterior inferior cerebellar artery and posterior inferior cerebellar artery branch from the basilar artery is the most common. Third, the basilar artery has the largest diameter among the major arteries. We expect that this anatomical information will aid in furthering research on cerebrovascular disease using cynomolgus monkeys.

Brainstem Venous Congestion Due to Transverse-sigmoid Sinus Dural Arteriovenous Fistula: Case Report and Literature Review.

Brainstem venous congestion due to dural arteriovenous fistula (dAVF) can mimic brainstem glioma and infarction. We report a case of a 56-year-old woman with a transverse-sigmoid sinus (TS) dAVF. On MRI, she presented with brainstem edema that was difficult to distinguish from brainstem glioma and infarction. She was referred to our hospital for mild dysarthria with right hemiparesis and a suspected left pontine glioma. On MRI, contrast enhancement of the lesion was demarcated by the pontine raphe, and the ipsilateral vein of Rosenthal was dilated. Cerebral angiography revealed TS dAVF with an isolated sinus. Transarterial followed by transvenous coil embolization was performed to reduce shunt flow, resulting in symptom improvement and normal findings on MRI and cerebral angiography. Brainstem venous congestion due to TS dAVF is as rare as adult brainstem glioma. Differentiating the above-mentioned three diseases on the basis of diagnostic imaging findings and clinical course is necessary for appropriate and timely treatment.

Rupture of Anterior Communicating Artery Aneurysm after Intravenous Thrombolysis for Acute Ischemic Stroke: A Case Report.

Objective: Rupture of intracranial aneurysms after tissue plasminogen activator (t-PA) administration for acute ischemic stroke with an unruptured cerebral aneurysm is rare. We report a case of ruptured cerebral aneurysm after t-PA administration. Case Presentation: A 74-year-old woman with dysarthria and left hemiparesis was admitted to our hospital, and acute lacunar infarction was found in the right corona radiata. One hour after t-PA administration, she complained of sudden headache and nausea, and her consciousness level deteriorated. Subarachnoid hemorrhage due to rupture of the anterior communicating aneurysm was confirmed and coil embolization was performed. Conclusion: T-PA administration for acute ischemic stroke with an unruptured cerebral aneurysm risks rupture of the cerebral aneurysm, and careful judgment is needed in each case.

Carotid Cavernous Fistula during Thrombectomy for Acute Ischemic Stroke: A Case Report.

Objective: We report a rare complication, carotid cavernous fistula (CCF), due to vessel perforation during thrombectomy for acute ischemic stroke (AIS). Case Presentation: An 88-year-old woman underwent thrombectomy for left C4 occlusion of the internal carotid artery. There was strong resistance at the medial C4 while the microguidewire was guided distally, and a CCF was found after deploying and retrieving the stent. It was thought to have been caused by perforation due to intracranial atherosclerotic stenosis of the internal carotid artery. Conclusion: During thrombectomy for intracranial large vessel occlusion underlying intracranial atherosclerotic stenosis, the risk of vascular injury should be kept in mind.

Macrophage Imaging of Cerebral Aneurysms with Ferumoxytol: an Exploratory Study in an Animal Model and in Patients.

OBJECTIVE: The purpose of this study is to assess the validity and feasibility of macrophage imaging using an ultrasmall superparamagnetic iron oxide nanoparticle, ferumoxytol, in the cerebral aneurysmal wall in an animal model and in humans. MATERIALS AND METHODS: Engulfment of ferumoxytol by primary culture of macrophages and RAW264.7 cells was assessed. Uptake of ferumoxytol was evaluated histologically in a cerebral aneurysmal model in rats. In an exploratory clinical study of magnetic resonance macrophage imaging, 17 unruptured aneurysms in 17 patients were imaged using thin-slice gapless magnetic resonance images of 2D-gradient-recalled echo (2D-GRE) and 3D-T1-fast-spin echo sequences on day 0 and of the same sequences with infusion of ferumoxytol 24 hours after the first imaging. Pre- and postinfusion images were evaluated independently by 2 medical doctors. RESULTS: Engulfment of ferumoxytol was confirmed in vitro, but the amount of ferumoxytol uptake was independent of the activation state or the differentiation state. Ferumoxytol uptake in CD68-positive cells was observed in the cerebral arterial walls of 4 out of 15 (26.7%) experimentally induced aneurysms in rats. In a clinical study, 17 aneurysms were enrolled and 2 aneurysms were not assessed because of incomplete images. Eleven aneurysms without oral intake of recent anti-inflammatory agents of the remaining 15 aneurysms showed ferumoxytol uptake on 2D-GRE subtraction images, and the size of the aneurysms was significantly related to positive images. CONCLUSIONS: Ferumoxytol uptake was confirmed in cultured macrophages and in the cerebral aneurysmal wall in rats. Thin-slice gapless magnetic resonance imaging with ferumoxytol in human cerebral aneurysmal walls may reflect macrophages in the cerebral aneurysmal wall, but its application to small-sized lesions may be restricted.

A sphingosine-1-phosphate receptor type 1 agonist, ASP4058, suppresses intracranial aneurysm through promoting endothelial integrity and blocking macrophage transmigration.

BACKGROUND AND PURPOSE: Intracranial aneurysm (IA), common in the general public, causes lethal subarachnoid haemorrhage on rupture. It is, therefore, of utmost importance to prevent the IA from rupturing. However, there is currently no medical treatment. Recent studies suggest that IA is the result of chronic inflammation in the arterial wall caused by endothelial dysfunction and infiltrating macrophages. The sphingosine-1-phosphate receptor type 1 (S1P1 receptor) is present on the endothelium and promotes its barrier function. Here we have tested the potential of an S1P1 agonist, ASP4058, to prevent IA in an animal model. EXPERIMENTAL APPROACH: The effects of a selective S1P1 agonist, ASP4058, on endothelial permeability and migration of macrophages across an endothelial cell monolayer were tested in vitro using a Transwell system, and its effects on the size of IAs were evaluated in a rat model of IA. KEY RESULTS: S1P1 receptor was expressed in endothelial cells of human IA lesions and control arterial walls. ASP4058 significantly reduced FITC-dextran leakage through an endothelial monolayer and suppressed the migration of macrophages across the monolayer in vitro. Oral administration of ASP4058 reduced the vascular permeability, macrophage infiltration and size of the IAs by acting as an S1P1 agonist in the rat model. This effect was mimicked by another two structurally-unrelated S1P1 agonists. CONCLUSION AND IMPLICATIONS: A selective S1P1 agonist is a strong drug candidate for IA treatment as it promotes the endothelial cell barrier and suppresses the trans-endothelial migration of macrophages in IA lesions.

Prostaglandin E2-EP2-NF-κB signaling in macrophages as a potential therapeutic target for intracranial aneurysms.

Intracranial aneurysms are common but are generally untreated, and their rupture can lead to subarachnoid hemorrhage. Because of the poor prognosis associated with subarachnoid hemorrhage, preventing the progression of intracranial aneurysms is critically important. Intracranial aneurysms are caused by chronic inflammation of the arterial wall due to macrophage infiltration triggered by monocyte chemoattractant protein-1 (MCP-1), macrophage activation mediated by the transcription factor nuclear factor κB (NF-κB), and inflammatory signaling involving prostaglandin E2 (PGE2) and prostaglandin E receptor subtype 2 (EP2). We correlated EP2 and cyclooxygenase-2 (COX-2) with macrophage infiltration in human intracranial aneurysm lesions. Monitoring the spatiotemporal pattern of NF-κB activation during intracranial aneurysm development in mice showed that NF-κB was first activated in macrophages in the adventitia and in endothelial cells and, subsequently, in the entire arterial wall. Mice with a macrophage-specific deletion of Ptger2 (which encodes EP2) or macrophage-specific expression of an IκBα mutant that restricts NF-κB activation had fewer intracranial aneurysms with reduced macrophage infiltration and NF-κB activation. In cultured cells, EP2 signaling cooperated with tumor necrosis factor-α (TNF-α) to activate NF-κB and synergistically induce the expression of proinflammatory genes, including Ptgs2 (encoding COX-2). EP2 signaling also stabilized Ccl2 (encoding MCP-1) by activating the RNA-stabilizing protein HuR. Rats administered an EP2 antagonist had reduced macrophage infiltration and intracranial aneurysm formation and progression. This signaling pathway in macrophages thus facilitates intracranial aneurysm development by amplifying inflammation in intracranial arteries. These results indicate that EP2 antagonists may therefore be a therapeutic alternative to surgery.

Activity of lower limb muscles during treadmill running at different velocities.

[Purpose] The present study aimed to determine changes in muscle activity while moving on a treadmill at various speeds. [Subjects] The activities of the left vastus lateralis, vastus medialis, hip adductors, lateral head of gastrocnemius, medial head gastrocnemius, soleus, and tibialis anterior of 10 healthy male university students were analyzed. [Methods] University students walked, jogged, and ran for 10 minutes each in random order, and then myogenic potentials were measured 10 minutes later for 30 seconds. The flexion angle of the lower limb upon initial contact, mid stance, and toe off were measured. [Results] The average walking, jogging, and running speeds were 3.6 ± 0.4, 6.7 ± 0.6, and 10.4 ± 1.3 km/h, respectively. The average electromyographic activities of the vastus medial, tibialis anterior, medial head of gastrocnemius, and lateral head of gastrocnemius significantly differed. All muscles were more active during jogging and running than walking. Only the soleus was more active during running than walking, and the activities of the hip adductors and vastus lateralis did not significantly differ. [Conclusion] Velocity is faster and the angles of the lower limbs and ground reaction force (GRF) are larger during running than walking. The vastus medialis and soleus worked more easily according to the angle of the knee joint, whereas the tibialis anterior worked more easily at faster velocities and the medial and lateral heads of the gastrocnemius worked more easily with an increased GRF.

Rapid formation of cerebral microbleeds after carotid artery stenting.

BACKGROUND: Recent studies reported that cerebral microbleeds (CMBs), i.e. small areas of signal loss on T(2)*-weighted gradient-echo (GE) imaging, could develop rapidly after acute ischemic stroke. We hypothesized that CMBs rapidly emerge after carotid artery stenting (CAS). OBJECTIVE: We investigated the frequency of and predisposing factors for CMBs after CAS. METHODS: We retrospectively examined MRI before and after CAS in 88 consecutive patients (average age: 71.7 ± 7.2 years, average rates of carotid stenosis: 72.6 ± 12.8%) who underwent CAS for carotid artery stenosis between March 1, 2009, and September 30, 2010. We defined new CMBs as signal losses that newly appeared on the follow-up GE. We examined the association of new CMBs with demographics, risk factors, and baseline MBs. RESULTS: Among 88 patients, 18 (20.5%) had CMBs initially, and 7 (8.0%) developed new CMBs right after CAS. New CMBs appeared on the same side of CAS in all of the 7 patients. New CMBs appeared significantly more frequently in the CMB-positive group than in the CMB-negative one (22% vs. 4%, p = 0.03) on the pre-CAS MRI. Multivariate analysis also revealed that the presence of CMBs before CAS was an independent predictor of new development of CMBs after CAS (odds ratio: 8.09, 95% confidence interval: 1.39-47.1). CONCLUSION: CMBs can develop rapidly after CAS, especially in patients with pre-existing CMBs. Since the existence of CMBs prior to CAS suggests a latent vascular damage which is vulnerable to hemodynamic stress following CAS, particular attention should be paid to the prevention of intracerebral hemorrhage due to hyperperfusion after CAS.

[Postoperative regression of desmoplastic infantile astrocytoma].

Desmoplastic infantile astrocytoma/ganglioglioma (DIA/DIG) is a rare tumor that is usually located superficially with a large cystic component. Gross total removal results in long-term survival in the majority of cases. In rare cases, postoperative regression of the residual tumor has been reported. We report another case of postoperative regression of DIA. A 3-month-old boy presented with increasing head circumference and developmental delay. A CT scan showed a large cystic tumor in his left parieto-occipital lobe. He underwent partial removal. The histopathological examination revealed an astrocytic tumor with marked desmoplasia. In the central portion of the tumor, anaplastic features, such as necrosis, mitosis, and high nucleus-cytoplasmic ratio, were noticed. Diagnosis was DIA. Six months later when he was admitted for the second-stage surgery, MRI showed regression of the tumor. The operation was therefore postponed and MRI at 12 months after surgery revealed further regression. This is the fifth case of postoperative or spontaneous regression of DIA/DIG.