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Intracellular K(+) plays an important role in controlling ion homeostasis for maintaining cell volume and inhibiting activity of pro-apoptotic enzymes. Cytoplasmic K(+) concentration is regulated by K(+) uptake via Na(+) -K(+) -ATPase and K(+) efflux through K(+) channels in the plasma membrane. The IsK (KCNE1) protein is known to co-assemble with KCNQ1 (KvLQT1) protein to form a K(+) channel underlying the slowly activating delayed rectifier K(+) outward current which delays voltage activation. In order to further study the activity and cellular localization of IsK protein, we constructed a C-terminal fusion of IsK with EGFP (enhanced green fluorescent protein). Expression of the fusion protein appeared as clusters located in the plasma membrane and induced degeneration of both transiently or stably transfected cells.

To describe the integration of magnetic resonance angiography (MRA) in neuronavigation procedures for microsurgery of intracranial aneurysms. MRA was combined with standard magnetic resonance image (MRI) acquisition in the image-guided planning for the microsurgical clipping of a saccular aneurysm in two patients (one 3-mm large middle cerebral artery and one 8-mm large pericallosal artery aneurysm, diagnosed by catheter angiography in both patients) using two different neurosurgical navigation systems. Conventional 3-D T1-weighted MRI with gadolinium and MRA pulse sequences were acquired in frameless stereotactic conditions the day before surgery and thereafter registered, allowing the definition a minimally invasive straight trajectory to the aneurysm neck. MRA-guided neurosurgery allowed a direct approach to the aneurysms at their proper location, reducing the invasiveness of the approach by tailoring the bone opening and reducing the duration and extension of brain retraction. The technique also avoided unnecessary dissection and exposure of the main trunks and collateral vessels. The aneurysms were successfully eradicated without complication. Integration of MRA in the planning and neuronavigation procedure for intracranial aneurysms may minimize the morbidity related to the surgical approach. This technique may be applicable more routinely using standard neuronavigation equipment., (Copyright 2004 W.S. Maney and Son Ltd)

The purpose of this study was to analyze immunohistochemical characteristics of the cell population in a radiosurgically obliterated cerebral arteriovenous malformation (AVM) after recurrent hemorrhage. Immunohistochemical reactions were carried out on paraffin-embedded histological sections for von Willebrand factor (FVIII), CD34 endothelial antigen (CD34), vimentin and alpha-smooth-muscle actin (SMA) cytoskeletal proteins. Histopathological analysis revealed that the majority of AVM channels were replaced by hypocellular scar tissue. However some of them still disclosed thrombus organization by granulation tissue seven years after radiosurgery. FVIII and CD34 reactions revealed vessel neoformation in thromboses. Proliferating spindle-shaped cells with SMA and vimentin expression were identified in the granulation tissue. These histopathological findings suggest the role of re-canalization in recurrence of hemorrhage following radiosurgical obliteration of the AVM. Contribution of myofibroblastic elements in the vessels' occlusion after radiosurgery is also demonstrated.

An implantable device (ADCON-L), which acts as a resorbable barrier to epidural fibrosis following lumbar discectomy, has been shown to minimize the formation of peridural fibrotic scar and to improve the post-operative outcome, in two large controlled and multi-center clinical trials. In this prospective study, 100 patients were treated with the device during their first-time lumbo-sacral discectomy surgeries and monitored for 12 months. During this time interval, four of these patients required re-operation. In these cases, epidural scar and ease of dissection were systematically evaluated and recorded. At the time of re-operation, in all four patients, absent or minimal soft scar tissue was found where ADCON-L had been placed, no adhesions to the involved root were observed, and the dissection was easier than expected; the healing of the surgical wound was excellent , and no residual implant material was found. These observations indicate that the use of ADCON-L at the time of the first lumbar disc surgery minimizes the hazards and difficulty that can be encountered in a subsequent revision surgery due to the presence of epidural fibrosis, and may therefore improve the chances of satisfactory outcome following re-operation.

Cavernous angioma (CA) is a hamartomatous hemorrhagic lesion which has received a great deal of attention in recent years due to improvement of neuroimaging with magnetic resonance and heightened clinical awareness. Long considered to be rare, its actual prevalence is now recognized to be of 0.9%. Cavernous angiomas may be multiple, particularly in patients with familial form. It may be associated with a variety of clinical syndromes attributed to focal microhemorrhages or less frequently to gross bleeding. CA are usually diagnosed between the age of 20 and 50 with a highest clinical incidence in the fourth decade. A female predominance is observed in regard to bleeding. The male patients are more at risk for seizures. The recent series of MR imaging confirm that CA even when multiple can be asymptomatic in a significant number of cases. Surgery is the treatment of choice in order to eliminate the risk of hemorrhage and improve the control of seizures. Minimally invasive approaches are now adopted with reduced post-operative morbidity. We report our experience in surgical management of cerebral CA and suggest a classification of the lesions according to surgical accessibility and residual morbidity.

Lower clivus and anterolateral foramen magnum meningiomas are rare but challenging tumors. Indeed, all access routes to their intradural anterolateral implantation appear unsafe since highly-functional local structures may not be sacrified or even retracted. Anterior and posterior surgical approaches have specific advantages and limitations. Different lateral extensions of the posterior approach have been described. They include a transposition of the vertebral artery, a partial occipital condylectomy and even the exposure and the section of the sigmoid sinus. Such posterolateral approaches offer the optimal access to anterolateral foramen magnum meningiomas and allow a total removal with a minimal morbidity. We report the surgical strategy that we applied for the last 6 anterolateral foramen magnum meningiomas in our department.

To validate specific, sensitive and quantitative markers of the rat model of Huntington's disease produced by the intrastriatal injection of quinolinic acid, we used striatal homogenate binding assays for [3H]MK-801-labelled N-methyl-D-aspartate receptors, [3H]SCH 23390-labelled D1 and [3H]sulpiride-labelled D2 dopamine receptors, [3H]CGS 21680-labelled adenosine A2 receptors, [3H]GBR 12935-labelled dopamine uptake sites, [3H]hemicholinium-3-labelled high affinity choline uptake sites and [3H]PK 11195-labelled glial cells, in 3 groups of rats: 1) lesioned only, 2) pretreated with MK-801, an antagonist of the N-methyl-D-aspartate receptor, to assess the non-N-methyl-D-aspartate-mediated toxicity of quinolinic acid, and 3) pretreated with MK-801 plus scopolamine, an anticholinergic drug that prevents MK-801 neuronal toxicity. [3H]MK-801 and [3H]PK 11195 are sensitive markers of quinolinic acid toxicity. In addition, [3H]SCH 23390, [3H]CGS 21680 and [3H]hemicholinium-3, are found to be specific markers of quinolinic acid-induced toxicity on striatonigral and striatopallidal projecting neurons, and on large interneurons, respectively. MK-801 pretreatment prevented the quinolinic acid-induced reduction in binding of [3H]MK-801, [3H]SCH 23390 and [3H]CGS 21680 but failed to do so for [3H]sulpride and [3H]hemicholinium-3, suggesting that quinolinic acid may act by mechanisms other than direct activation of N-methyl-D-aspartate receptors. Combined pretreatment with MK-801 and scopolamine increased the protection against quinolinic acid, suggesting an involvement of the cholinergic system.

This work presents a prospective morphological and quantitative analysis of 43 intracranial pressure recordings performed on normal pressure hydrocephalic patients. This analysis led us to separate Lundberg's B waves into different subtypes and to refine the definition of the 'Plateau' wave. Two B wave subtypes named Great Symmetrical wave and Intermediate wave appeared correlated with the surgical improvement. In addition, the degree of post-operative improvement was correlated with the frequency of Intermediate wave. An extended quantitative classification of intracranial pressure waves is proposed that can be used alone to determine which patients should undergo a shunting procedure and which one should the most improve.