Outer membrane proteins are vital for Gram-negative bacteria and organisms that inherited organelles from them. Proteins from the Omp85/BamA family conduct the insertion of membrane proteins into the outer membrane. We show that an eight-stranded outer membrane β-barrel protein, TtoA, is inserted and folded into liposomes by an Omp85 homologue. Furthermore, we recorded the channel conductance of this Omp85 protein in black lipid membranes, alone and in the presence of peptides comprising the sequence of the two N-terminal and the two C-terminal β-strands of TtoA. Only with the latter could a long-living compound channel that exhibits conductance levels higher than those of the Omp85 protein alone be observed. These data support a model in which unfolded outer membrane protein after docking with its C-terminus penetrates into the transmembrane β-barrel of the Omp85 protein and augments its β-sheet at the first strand. Augmentation with successive β-strands leads to a compound, dilated barrel of both proteins.

Objective Microsurgical resection of cavernous sinus meningiomas (CSM) is associated with a high rate of incomplete resection, recurrence, and the risk for permanent, severe cranial nerve deficits. Stereotactic radiosurgery (SRS) has evolved as alternative treatment for primary and recurrent CSM. Here, we report about the long-term clinical and radiological follow-up (FU) of a unique cohort of patients with CSM treated with LINAC or Cyberknife based SRS. Methods In this single-center retrospective analysis, we include all patients with CSM who underwent single fraction SRS between 1993 and 2016. Clinical and radiological tumor control were evaluated by the Kaplan–Meier method. Additionally, patient data were analyzed in terms of symptom control and incidence of side effects rated by the common terminology criteria for adverse events (CTCAE; v4.03). Results 116 patients (female/male = 91/25; median age, 54 years; range, 33–82 years) were included. Mean tumor volume was 5.7 ± 3.3 cm3 (range, 0.6–16.2 cm3), the median marginal dose was 12.6 Gy applied to isodose levels of 75%. Median clinical FU was 55 months (range, 3–226 months). Tumor control was 98% after 2 and 5 years and 90% after 10 years. Twelve patients (10.3%) had permanent or transient radiation related toxicity (CTCAE I–III). An improvement of symptoms was observed in 26.7% of the symptomatic patients (n = 20 of 75). Conclusion SRS for CSM provides excellent long-term tumor and symptom control without considerable permanent side effects. Thus, SRS should be considered when counseling patients suffering from CSM.

Abstracts iii96NEURO-ONCOLOGY • MAY 2017 and bone when infiltrated. The histological grading is the most important prognostic factor. Meningiomas may recur after total surgical resection. WHO grade I meningiomas show a recurrence rate between 7-25%. Atypical meningiomas (WHO grade II) between 29-52%. Anaplastic meningiomas (WHO grade III) between 50-94%. From recent studies the Wnt pathway is emerging as involving in growth and progression of meningioma. However, molecular mechanism driving meningioma invasion are not completely clarified. The gene Dkk-3 (Dickkopf WNT signaling pathway inhibitor 3) encodes one of Dickkopf-related protein family of proteins. The activity of this gene is a tumor-suppressive type. The Dkk-3 protein (Dickkopf-related protein 3) is involved in embryonic development through its interactions with the WNT. The REIC/Dkk-3 expression has been shown to be down-regulated in various cancer cell lines. Aim of our study was to study the role of Dkk-3 expression and claudin-5 in meningiomas of different histotype and histological grade. Material and METHODS: We evaluated how meningiomas modify DKK-3 expression in 20 tumors biopsies assessing both immunohistochemistry and western blotting. The tissue samples were embedded in paraffin for immunohistochemical analysis. The expression strength was analyzed and graded based on the positive ratio and intensity of immunoreactivity. The molecular analyses were performed on frozen sections of tumor tissue, by Western Blot method. Statistical analysis was also performed. RESULTS: The expression of Dkk-3 protein and claudin-5 were significantly reduced in meningioma samples compared to controls. These results were confirmed by immunohistochemistry that reveals a slight expression of Dkk-3 protein in meningioma samples examined. It was also highlighted an irregular positivity of claudin-5 protein, on vascular localization. Claudin-5 levels were inversely regulated in meningiomas proteic extract with decreased levels compared to controls. CONCLUSIONS: Overexpression of Dkk-3 has been shown to mediate potent anti-tumor effects including reduced cell proliferation, independent growth, invasion and metastasis, and induced cancer cell specific apoptosis.Our preliminary results can suggest that in meningiomas Dkk-3 and Claudin-5 are downregulated. There is an alteration of the BBB. There is a decreasing of apoptotic susceptibility. The immunoreactivity of vascular neoplastic endothelium can suggest a role in angiogenesis. We suggest that the re-establishment of Dkk-3 expression can represent a new potential therapeutic approach in meningiomas treatment also by modulation of blood-brain barrier permeability. Meningioma is the most commonly diagnosed primary brain tumor and is associated with significant morbidity. Children treated with therapeutic radiation to the head are at almost ten-fold risk of radiation-associated meningioma (RAM). RAM tumors are associated with aggressive histological features and reduced survival but treatment options remain limited. T...