Estimation of wall shear stress dynamic fluctuations in intracranial atherosclerotic lesions using computational fluid dynamics.

Objective: Intracranial stenosis (IS) is associated with significant morbidity and mortality from hypoperfusion and thromboembolism. We used computational fluid dynamic methods to analyze luminal patterns of wall shear stress (WSS), a known critical modulator of endothelial function, within patient-based IS lesions undergoing percutaneous angioplasty and stenting.

Methods: High-resolution three-dimensional rotational angiographic data sets were reconstructed to yield a fine-resolution computational mesh allowing application of pulsatile computational fluid dynamic analysis with a non-Newtonian realistic model of blood.

Stent-mediated wedging of a calcific embolus to recanalize an occluded middle cerebral artery: technical case report.

Objective: Calcific cerebral emboli are rare yet pose a difficult therapeutic challenge because of their lack of response to thrombolytic therapy and their propensity for fragmentation.

Clinical Presentation: A 75-year-old woman developed aphasia and hemiparesis after cardiac catheterization from a near-occlusive calcific embolus to the left middle cerebral artery origin. The calcific embolus was shown to be hemodynamically limiting by computed tomographic perfusion and diffusion-weighted magnetic resonance imaging.

[Whipple's disease with generalized lymphadenopathy].

A case of Whipple's disease in 44 year-old man with generalized limphadenopathy of superficial and retroperitoneal lymph nodes was presented. Differential diagnostics with lymphatic neoplasm was necessary.

Stent graft treatment of cerebrovascular wall defects: intermediate-term clinical and angiographic results.

Objective: Endovascular stent graft (SG) deployment offers a useful vessel-preserving strategy for vascular wall lesions such as pseudoaneurysms and fistulae. Although deployment of expanded polytetrafluoro-ethylene-covered SGs within the carotid and vertebral arteries is technically feasible, data on long-term efficacy, safety, and patency rate remain sparse.

Methods: Six patients with traumatic (n = 4), iatrogenic (n = 1), or spontaneous (n = 1) internal carotid and vertebral artery injuries (direct carotid-cavernous fistula, n = 2; pseudoaneurysms, n = 4) were treated with nine balloon-mounted coronary expanded polytetrafluoro-ethylene SGs.

Angiographic detection of carotid and vertebral arterial injury in the high-energy blunt trauma patient.

Background And Objective: Injury to the carotid and vertebral arteries is an identified risk to patients after blunt high-energy cranio-cervical trauma with an associated risk of thromboembolic stroke. We sought to determine the incidence, features, and risk factors of arterial injury using selective cerebral angiography in a high-risk trauma patient subset.

Methods: Blunt trauma patients with a high-energy mechanism were selected to undergo screening cerebral angiography if they met one of the following criteria: (1) cervical spine hyperextension/hyperflexion injury, (2) skull-base or facial fracture, (3) lateralizing neurologic deficit, ischemic deficit, or cerebral infarction, or (4) hemorrhage of arterial origin.

Polyethylenimine PEI F25-LMW allows the long-term storage of frozen complexes as fully active reagents in siRNA-mediated gene targeting and DNA delivery.

Background: Polyethylenimines (PEIs) are synthetic, charged polymers which function as transfection reagents based on their ability to compact DNA into complexes. Recently, PEI-mediated delivery of nucleic acids has been extended towards small interfering RNAs (siRNAs) which are instrumental in the induction of RNA interference (RNAi). Since RNAi represents a powerful method for specific gene silencing, the PEI-based delivery of siRNAs is a promising tool for novel putative therapeutic strategies.

HMGA2 gene is a promising target for ovarian cancer silencing therapy.

Ovarian cancer is one of the most lethal gynecological malignancies and the small success rate of routine therapeutic methods justifies efforts to develop new approaches. Evaluation of targets for effective inhibition of ovarian cancer cell growth should precipitate clinical application of gene silencing therapy. In our previous work, we showed upregulation of HMGA2 gene expression as a result of Ras-induced rat ovarian surface epithelial cell transformation.

Decompressive Craniectomy.

Decompressive Craniectomy (DC) is used to treat elevated intracranial pressure that is unresponsive to conventional treatment modalities. The underlying cause of intracranial hypertension may vary and consequently there is a broad range of literature on the uses of this procedure. Traumatic brain injury (TBI), middle cerebral artery (MCA) infarction, and aneurysmal subarachnoid hemorrhage (SAH) are three conditions for which DC has been predominantly used in the past.

Iatrogenic vasospasm in carotid artery stent angioplasty with distal protection devices.

Object: Distal protection devices (DPDs) have decreased the risk of embolic stroke among patients with carotid artery (CA) disease undergoing CA stent placement. The FilterWire EX is a first-generation fixed-basket DPD with a filter rigidly attached to a guidewire. Second-generation mobile-basket DPDs (RX Accunet or SpiderFX) allow movement of the filter relative to the guidewire and can thus reduce the potential for vessel irritation, vasospasm, or intimal injury during CA stent placement.

PEG grafting of polyethylenimine (PEI) exerts different effects on DNA transfection and siRNA-induced gene targeting efficacy.

Background: Gene targeting by RNA interference (RNAi) is mediated through small interfering RNA (siRNA), which, as plasmid DNA molecules, can be delivered into cells by polyethylenimines (PEI). Grafting with poly(ethylene glycol) has been introduced previously to improve PEI biocompatibility; however, data on the effects of PEGylation have been somewhat contradictory and various PEI(-PEG) need to be evaluated independently for DNA transfection and siRNA gene targeting efficacies.

Aim: We directly compare plasmid DNA transfection and siRNA-mediated gene targeting efficacies, employing a larger set of polyethylenimine-graft-poly(ethylene glycol) (PEI-g-PEG; PEI(-PEG)) with different molecular weights and degrees of PEG substitution.

Aneurysmal subarachnoid hemorrhage: update for emergency physicians.

Aneurysmal subarachnoid hemorrhage (SAH) is a serious cause of stroke that affects 30,000 patients in North America annually. Due to a wide spectrum of presentations, misdiagnosis of SAH has been reported to occur in a significant proportion of cases. Headache, the most common chief complaint, may be an isolated finding; the neurological examination may be normal and neck stiffness absent.

Wall shear stress gradient analysis within an idealized stenosis using non-Newtonian flow.

Objective: The endothelium is functionally regulated by the magnitude and spatiotemporal gradients of wall shear stress (WSS). Although flow separation and reversal occur beyond high-grade stenoses, little is known of the WSS pattern within clinically relevant mild to moderate stenoses.

Methods: An axisymmetric geometry with 25, 50, and 75% stenosis criteria (quantified in accordance with the North American Symptomatic Carotid Endarterectomy Trial) was used to generate a high-resolution, hybrid, tetrahedral-hexahedral computational mesh with boundary-layer enrichment to improve near-wall shear stress gradient (WSSG) computation.

Prediction of complex flow patterns in intracranial atherosclerotic disease using computational fluid dynamics.

Objective: Although carotid and vertebral intracranial atherosclerotic disease (ICAD) can lead to both hemodynamic insufficiency and thromboembolism, its fluid dynamic properties remain undefined because of its intricate features and complex three-dimensional geometry. We used computational fluid dynamic (CFD) analysis to model the hemodynamics of symptomatic ICAD lesions.

Methods: Nine ICAD lesions (six carotid, two vertebral, one middle cerebral) underwent high-resolution catheter-based digital rotational angiography.

Nelson syndrome: comprehensive review of pathophysiology, diagnosis, and management.

Nelson syndrome (NS) is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenal gland removal performed for the treatment of Cushing disease. It is characterized by excess adreno-corticotropin secretion and hyperpigmentation of the skin and mucus membranes. The authors present a comprehensive review of the pathophysiology, diagnosis, and management of NS.

Complications of Neuroform stent in endovascular treatment of intracranial aneurysms.

Background: The Neuroform stent can help in the treatment of difficult, wide-necked intracranial aneurysms. The objective of our study is to report some of the challenges associated with the Neuroform stent in the treatment of intracranial aneurysms.

Methods: From January 2003 to August 2006, consecutive patients treated with Neuroform stent for intracranial aneurysms were prospectively enrolled.

Sapphire platinum detachable coil experience in a tertiary-care facility.

Background: The Guglielmi Detachable Coil introduced by the Boston Scientific Corporation has been widely used for endovascular coiling of aneurysm. Recently, Sapphire platinum detachable coils (eV3, Irvine, CA) have been introduced for aneurysm coiling. Herein, we report our clinical experience with the Sapphire coil to evaluate the incidence of coil related complications and the rate of aneurysm occlusion.

Decompressive hemicraniectomy for the treatment of intractable intracranial hypertension after aneurysmal subarachnoid hemorrhage.

Background And Purpose: Decompressive hemicraniectomy and duroplasty (DHCD) can improve survival in patients with severe cerebral edema. We present our clinical experience with DHCD for the treatment of refractory elevated intracranial pressure (ICP) in patients with aneurysmal subarachnoid hemorrhage (aSAH).

Methods: DHCD was performed in 16 patients (11 female; median age, 49.

Hypertonicity triggers RhoA-dependent assembly of myosin-containing striated polygonal actin networks in endothelial cells.

Endothelial cells respond to mechanical stresses of the circulation with cytoskeletal rearrangements such as F-actin stress fiber alignment along the axis of fluid flow. Endothelial cells are exposed to hypertonic stress in the renal medulla or during mannitol treatment of cerebral edema. We report here that arterial endothelial cells exposed to hypertonic stress rearranged F-actin into novel actin-myosin II fibers with regular 0.

Electrocautery-induced ignition of spark showers and self-sustained combustion of onyx ethylene-vinyl alcohol copolymer.

Objective: Ethylene-vinyl alcohol copolymer mixed with micronized tantalum (Ta) as radiopacifier (Onyx; Micro Therapeutics Inc., Irvine, CA) has emerged as a useful liquid embolic agent for vascular malformations. We describe intraoperative ignition of Onyx-embolized tissue and undertake an in vitro investigation to reproduce and characterize this hazard.

Use of the Amplatzer vascular plug as an anchoring scaffold for coil-mediated parent vessel occlusion: technical case report.

Objective: Parent vessel sacrifice is a useful treatment strategy for fusiform intracranial aneurysms. Originally performed using the detachable silicone balloon, endovascular arterial occlusion is currently achieved using coils, a process which can be limited by coil mass migration.

Methods: We demonstrate the use of the Amplatzer vascular plug as a fixed anchor within the target parent vessel to facilitate coil-mediated occlusion, especially in vascular segments not encased by a bony canal.

Preoperative embolization of hypervascular spinal metastases using percutaneous direct injection with n-butyl cyanoacrylate: technical case report.

Objective: Intraoperative blood loss constitutes a major cause of perioperative morbidity in surgical decompression and reconstruction of highly vascular spinal metastatic tumors. We propose a technique for embolization of highly vascular vertebral metastases using percutaneous direct injection using n-butyl cyanoacrylate (NBCA) instead of polymethylmethacrylate to complement preoperative transarterial embolization and to minimize operative blood loss.

Methods: Five patients with renal cell carcinoma metastases to the spine (one cervical, one thoracic, and three lumbar) underwent embolization by percutaneous direct injection of the affected vertebrae with a mixture of NBCA and iodized oil to supplement transarterial embolization with polyvinyl alcohol particles and fibered platinum coils.

Differential release of plasminogen activator inhibitors (PAIs) during dual perfusion of human placenta: implications in preeclampsia.

Plasminogen activator inhibitors (PAIs) play critical roles in regulating cellular invasion and fibrinolysis. An increase in the ratio of PAI-1/PAI-2 in placenta and maternal serum is suggested to result in excessive intervillous fibrin deposition and placental infarction in pregnancies complicated by preeclampsia (PE) and intrauterine growth restriction (IUGR). In the current study we used dual (maternal and fetal) perfusion of human term placentas to examine the release of PAIs to the intervillous space.