[Not Available]. / Résultats du traitement radiochirurgical Gamma Knife des malformations artério-veineuses cérébrales.

Gamma Knife treatments of arteriovenous malformations (AVM) are performed for about 40 years. This article presents the results of 123 patients treated for a brain AVM at the Gamma Knife Center ULB-Hôpital Erasme. Radiosurgical treatment is proposed following multidisciplinary discussion of the best therapeutic strategy based on specific parameters of the AVM. Gamma Knife irradiation was achieved for an AVM residue after endovascular embolization for 84% of patients, after microsurgery for 7% of patients, or after previous radiosurgical irradiation for 6% of patients. The whole volume of the nidus was irradiated in a single session for all patients. A mean margin dose of 22.3 Gy was delivered to the nidus, which had a mean volume of 3.3 cc. The maximum dose ranged from 30 Gy to 50 Gy (mean 44.1 Gy). All patients were prospectively followed after treatment with serial angio-MR and/or conventional angiography. A retrospective analysis shows complete obliteration of the AVM for 109 patients (89%) after 6 to 52 months (mean 32 months). For 14 patients the nidus was only partially obliterated from the radiosurgical procedure; for 9 patients a second irradiation was performed with subsequent complete occlusion of the AVM in all cases. So, 118 of 123 patients (96%) irradiated by Gamma Knife in 1 or 2 sessions were cured. Four patients bled after irradiation and before complete occlusion of the AVM, with neurological deficit for 2 patients. Transient neurological symptoms develop after treatment for 12 patients (10%), associated with postradic edema treated with corticoids. Permanent neurological worsening occurred in 5 patients (4%). Gamma Knife treatment of cerebral arteriovenous malformations is a highly efficient and low-risk therapy when used by a multidisciplinary team.

The lipid phosphatase SHIP2 controls insulin sensitivity.

Insulin is the primary hormone involved in glucose homeostasis, and impairment of insulin action and/or secretion has a critical role in the pathogenesis of diabetes mellitus. Type-II SH2-domain-containing inositol 5-phosphatase, or 'SHIP2', is a member of the inositol polyphosphate 5-phosphatase family. In vitro studies have shown that SHIP2, in response to stimulation by numerous growth factors and insulin, is closely linked to signalling events mediated by both phosphoinositide-3-OH kinase and Ras/mitogen-activated protein kinase. Here we report the generation of mice lacking the SHIP2 gene. Loss of SHIP2 leads to increased sensitivity to insulin, which is characterized by severe neonatal hypoglycaemia, deregulated expression of the genes involved in gluconeogenesis, and perinatal death. Adult mice that are heterozygous for the SHIP2 mutation have increased glucose tolerance and insulin sensitivity associated with an increased recruitment of the GLUT4 glucose transporter and increased glycogen synthesis in skeletal muscles. Our results show that SHIP2 is a potent negative regulator of insulin signalling and insulin sensitivity in vivo.

Integration of the metabolic data of positron emission tomography in the dosimetry planning of radiosurgery with the gamma knife: early experience with brain tumors. Technical note.

The purpose of this study was to assess the use of positron emission tomography (PET) as a stereotactic planning modality for gamma knife radiosurgery (GKS). The authors developed and validated a technique for fiducial marker imaging, importation, and handling of PET data for integration into GammaPlan planning software. The clinical feasibility in applying this approach to a selected group of patients presenting with recurrent glial tumors or metastases was evaluated. Positron emission tomography data can be integrated into GammaPlan, allowing a high spatial accuracy, as validated using a phantom. Positron emission tomography data were successfully combined with magnetic resonance (MR) images to define the target volume for the radiosurgical treatment of patients with recurrent glioma or metastasis. This approach may contribute to optimizing target selection for infiltrating or ill-defined brain lesions. Because PET is also useful for the pretreatment and follow-up evaluation, the use of stereotactic PET in these patients can enable an accurate comparison of PET-based metabolic data with MR-based anatomical data. This could give a better understanding of the metabolic changes following radiosurgery. The ability to use PET data in GKS represents a crucial step toward further developments in radiosurgery, as this approach provides additional information that may open new perspectives for the optimization of the treatment of brain tumors.