Enhanced hydrogen peroxide generation accompanies the beneficial bioenergetic effects of methylene blue in isolated brain mitochondria

The redox dye methylene blue (MB) is proven to have beneficial effects in various models of neurodegenerative diseases. Here we investigated the effects of MB (100 nM, 300 nM, and 1 μM) on key bioenergetic parameters and on H2O2 production/elimination in isolated guinea pig brain mitochondria under normal as well as respiration-impaired conditions. As measured by high-resolution Oxygraph the rate of resting oxygen consumption was increased, but the ADP-stimulated respiration was unaffected by MB with any of the substrates (glutamate malate, succinate, or α-glycerophosphate) used for supporting mitochondrial respiration. In mitochondria treated with inhibitors of complex I or complex III MB moderately but significantly increased the rate of ATP production, restored ΔΨm, and increased the rate of Ca2+ uptake. The effects of MB are consistent with transferring electrons from upstream components of the electron transport chain to cytochrome c, which is energetically favorable when the flow of electrons in the respiratory chain is compromised. On the other hand, MB significantly increased the production of H2O2 measured by Amplex UltraRed fluorimetry under all conditions, in resting, ATP-synthesizing, and respiration-impaired mitochondria, with each substrate combination supporting respiration. Furthermore, it also decreased the elimination of H2O2. Generation of H2O2 without superoxide formation, observed in the presence of MB, is interpreted as a result of reduction of molecular oxygen to H2O2 by the reduced MB. The elevated generation and impaired elimination of H2O2 should be considered for the overall oxidative state of mitochondria treated with MB

Gorilla Park: A Sustainable Space for All (Mobility pilot project)

This project explores urban design and urban systems solutions to address issues of shared mobility, accessibility and urban fragmentation. It is a pilot project to create a park and a shared mobility hub in the borough of Rosemont-La-Petite-Patrie in Montreal. This is to be a node of many in a metropolitan-wide shared mobility system. A shared mobility approach to city planning incorporates notions of Transportation Oriented Development (TOD) and Pedestrian Oriented Development (POD) and links it to notions of smart cities and autonomous transportation. The challenge at hand was to create a public space that incorporates these questions as well as notions of placemaking, community planning and open urbanisms. The project is part of an urban design studio taught in the Department of Geography Planning and Environment at Concordia University in Montreal, and it takes place in the context of the first edition of the CitéStudio Montreal program, which fosters collaborations between academics, students and the city government. The solutions explored in this project were conceived by the students of URBS333 - Urban Laboratory (class of 2019-2020) under the supervision of the instructor (S. De la Llata) and in collaboration with stakeholders and neighbours of Gorilla Park. The solutions are divided into five thematic axes (Sustainability, Mobility and Accessibility, Community Engagement, Hard Design and Soft Design)

An Exo-Kuiper Belt with An Extended Halo around HD 191089 in Scattered Light

International audienceWe have obtained Hubble Space Telescope (HST) STIS and NICMOS, and Gemini/GPI scattered light images of the HD 191089 debris disk. We identify two spatial components: a ring resembling Kuiper Belt in radial extent (FWHM: ∼25 au, centered at ∼46 au), and a halo extending to ∼640 au. We find that the halo is significantly bluer than the ring, consistent with the scenario that the ring serves as the "birth ring" for the smaller dust in the halo. We measure the scattering phase functions in the 30 •-150 • scattering angle range and find the halo dust is both more forward-and backward-scattering than the ring dust. We measure a surface density power law index of −0.68 ± 0.04 for the halo, which indicates the slowdown of the radial outward motion of the dust. Using radiative transfer modeling, we attempt to simultaneously reproduce the (visible) total and (near-infrared) polarized intensity images of the birth ring. Our modeling leads to mutually inconsistent results, indicating that more complex models, such as the inclusion of more realistic aggregate particles, are needed