Diffuse intrinsic pontine glioma (DIPG) is one of the most frequent malignant pediatric brain tumor and its prognosis is universaly fatal. No significant improvement has been made in last thirty years over the standard treatment with radiotherapy. To address the paucity of understanding of DIPGs, we have carried out integrated molecular profiling of a large series of samples obtained with stereotactic biopsy at diagnosis. While chromosomal imbalances did not distinguish DIPG and supratentorial tumors on CGHarrays, gene expression profiling revealed clear differences between them, with brainstem gliomas resembling midline/thalamic tumours, indicating a closely-related origin. Two distinct subgroups of DIPG were identified. The first subgroup displayed mesenchymal and pro-angiogenic characteristics, with stem cell markers enrichment consistent with the possibility to grow tumor stem cells from these biopsies. The other subgroup displayed oligodendroglial features, and appeared largely driven by PDGFRA, in particular through amplification and/or novel missense mutations in the extracellular domain. Patients in this later group had a significantly worse outcome with an hazard ratio for early deaths, ie before 10 months, 8 fold greater that the ones in the other subgroup (p = 0.041, Cox regression model). The worse outcome of patients with the oligodendroglial type of tumors was confirmed on a series of 55 paraffin-embedded biopsy samples at diagnosis (median OS of 7.73 versus 12.37 months, p = 0.045, log-rank test). Two distinct transcriptional subclasses of DIPG with specific genomic alterations can be defined at diagnosis by oligodendroglial differentiation or mesenchymal transition, respectively. Classifying these tumors by signal transduction pathway activation and by mutation in pathway member genes may be particularily valuable for the development of targeted therapies.

Objective: Failure of noninvasive ventilation (NIV) has been associated with short-term adverse effects related to the use of masks. The aim of this study was to compare the incidence, type and intensity of adverse effects, as well as the comfort, of total face masks (TFMs), facial masks (FMs) and nasal masks (NMs) during NIV. Methods: This was a randomized crossover trial involving 24 healthy volunteers submitted to six sessions of NIV in bilevel positive airway pressure mode using the TFM, FM and NM masks at low and moderate-to-high pressure levels. A written questionnaire was applied in order to evaluate eleven specific adverse effects related to the use of the masks. Comfort was assessed using a visual analog scale. The CO 2 exhaled into the ventilator circuit was measured between the mask and the exhalation port. Results: The performance of the TFM was similar to that of the NM and FM in terms of comfort scores. Higher pressure levels reduced comfort and increased adverse effects, regardless of the mask type. When the TFM was used, there were fewer air leaks and less pain at the nose bridge, although there was greater oronasal dryness and claustrophobia. Air leaks were most pronounced when the FM was used. The partial pressure of exhaled CO 2 entering the ventilator circuit was zero for the TFM. Conclusions: The shortterm adverse effects caused by NIV interfaces are related to mask type and pressure settings. The TFM is a reliable alternative to the NM and FM. Rebreathing of CO 2 from the circuit is less likely to occur when a TFM is used.Keywords: Intermittent positive-pressure ventilation; Masks/adverse effects; Respiratory insufficiency; Equipment failure analysis. ResumoObjetivo: Falhas da ventilação não-invasiva (VNI) têm sido relacionadas a efeitos adversos agudos do uso de máscaras. O objetivo deste estudo foi comparar a incidência, tipo e intensidade de eventos adversos e conforto das máscaras facial total (MFT), facial (MF) e nasal (MN). Métodos: Estudo randomizado, tipo cruzado, em 24 voluntá-rios sadios submetidos a seis períodos de VNI, modo bilevel positive airway pressure em ajustes de baixa e moderada a alta pressão. Foi aplicado um questionário de avaliação de onze eventos adversos especificamente relacionados ao uso das máscaras. O conforto foi avaliado por escala visual analógica. O CO 2 exalado no circuito foi medido entre a conexão da máscara e o orifício de exalação. Resultados: A MFT teve desempenho similar a MF e MN quanto a escores de conforto. A aplicação de pressões mais altas reduziu o conforto e aumentou a incidência e a intensidade dos eventos adversos, independentemente do tipo de máscara. A MFT teve melhor desempenho quanto a vazamentos e dor no nariz e pior resultado quanto ao ressecamento oronasal e claustrofobia. A MF teve o pior resultado quanto a vazamentos. A pressão parcial do CO 2 exalado no circuito permaneceu em zero com a MFT. Conclusões: Os eventos adversos agudos causados pelas interfaces de VNI são relacionados ao tipo de máscara e aos parâmetros de press...

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