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Weiss N.,University of Calgary | Zamponi G.W.,University of Calgary | De Waard M.,Grenoble Institute of Neuroscience | De Waard M.,Joseph Fourier University
Communicative and Integrative Biology | Year: 2012

Low-voltage-activated T-type calcium channels act as a major pathway for calcium entry near the resting membrane potential in a wide range of neuronal cell types. Several reports have uncovered an unrecognized feature of T-type channels in the control of vesicular neurotransmitter and hormone release, a process so far thought to be mediated exclusively by high-voltage-activated calcium channels. However, the underlying molecular mechanisms linking T-type calcium channels to vesicular exocytosis have remained enigmatic. In a recent study, we have reported that Cav3.2 T-type channel forms a signaling complex with the neuronal Q-SNARE syntaxin-1A and SNAP-25. This interaction that relies on specific Cav3.2 molecular determinants, not only modulates T-type channel activity, but was also found essential to support low-threshold exocytosis upon Cav3.2 channel expression in MPC 9/3L-AH chromaffin cells. Overall, we have indentified an unrecognized regulation pathway of T-type calcium channels by SNARE proteins, and proposed the first molecular mechanism by which T-type channels could mediate low-threshold exocytosis. © 2012 Landes Bioscience. Source


Objective: To evaluate the feasability and the potential usefulness of functional MRI (fMRI) for the evaluation of brain functions after severe brain injury, when compared to a multimodal approach (evoked potentials [EP] and Positron Emission Tomography [PET] examinations). Material and methods: Seven patients (mean age: 49years [23-73], three males, four females) presenting with coma after acute severe brain injuries underwent fMRI (auditive, visual, somesthesic), 18F-FDG PET and EP (auditive, visual, somesthesic) within a 3-day period of time in a mean of 120 days after initial brain injury. fMRI activations in somesthesic, visual and auditive cortical areas were compared to EP (28 possible comparisons) and to the metabolic activity on PET examination in the same anatomical areas (21 possible comparisons). Results: In case of availability, results were concordant between fMRI and PET in 10 comparisons but not in one, and between fMRI and EP in 11 comparisons but not in four. Conclusions: In many patients, there is a good concordance between fMRI and brain functions suggested by EP and metabolic activity demonstrated with PET. In few others, fMRI can be integrated in the early evaluation of brain functions to further augment our capacity for a proper evaluation of brain functions in critically ill patients. © 2009 Elsevier Masson SAS. Source


Ratti P.-L.,University Paul Sabatier | Ratti P.-L.,French Institute of Health and Medical Research | Ratti P.-L.,Sleep and Epilepsy Center | Sierra-Pena M.,University Paul Sabatier | And 11 more authors.
PLoS ONE | Year: 2015

Objective To characterize parasomnia behaviors on arousal from NREM sleep in Parkinson's Disease (PD) and Multiple System Atrophy (MSA). Methods From 30 patients with PD, Dementia with Lewy Bodies/Dementia associated with PD, or MSA undergoing nocturnal video-polysomnography for presumed dream enactment behavior, we were able to select 2 PD and 2 MSA patients featuring NREM Parasomnia Behviors (NPBs). We identified episodes during which the subjects seemed to enact dreams or presumed dream-like mentation (NPB arousals) versus episodes with physiological movements (no-NPB arousals). A time-frequency analysis (Morlet Wavelet Transform) of the scalp EEG signals around each NPB and no- NPB arousal onset was performed, and the amplitudes of the spectral frequencies were compared between NPB and no-NPB arousals. Results 19 NPBs were identified, 12 of which consisting of 'elementary' NPBs while 7 resembling confusional arousals. With quantitative EEG analysis, we found an amplitude reduction in the 5-6 Hz band 40 seconds before NPBs arousal as compared to no-NPB arousals at F4 and C4 derivations (p<0.01).Conclusions Many PD and MSA patients feature various NREM sleep-related behaviors, with clinical and electrophysiological differences and similarities with arousal parasomnias in the general population. Significance This study help bring to attention an overlooked phenomenon in neurodegenerative diseases. © 2015 Ratti et al. Source

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