University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

Doxorubicin Loaded Magnetic Polymersomes: Theranostic Nanocarriers for MR Imaging and Magneto-Chemotherapy

Abstract: Hydrophobically modified maghemite (γ-Fe2O3) nanoparticles were encapsulated within the membrane of poly(trimethylene carbonate)-b-poly(l-glutamic acid) (PTMC-b-PGA) block copolymer vesicles using a nanoprecipitation process. This formation method gives simple access to highly magnetic nanoparticles (MNPs) (loaded up to 70 wt %) together with good control over the vesicles size (100−400 nm). The simultaneous loading of maghemite nanoparticles and doxorubicin was also achieved by nanoprecipitation. The deformation of the vesicle membrane under an applied magnetic field has been evidenced by small angle neutron scattering. These superparamagnetic hybrid self-assemblies display enhanced contrast properties that open potential applications for magnetic resonance imaging. They can also be guided in a magnetic field gradient. The feasibility of controlled drug release by radio frequency magnetic hyperthermia was demonstrated in the case of encapsulated doxorubicin molecules, showing the viability of the concept...

The CO-to-H2 Conversion Factor From Infrared Dust Emission Across the Local Group

Abstract: We estimate the conversion factor relating CO emission to H2 mass, alpha_CO, in five Local Group galaxies that span approximately an order of magnitude in metallicity - M31, M 33, the Large Magellanic Cloud (LMC), NGC 6822, and the Small Magellanic Cloud (SMC). We model the dust mass along the line of sight from infrared (IR) emission and then solve for the alpha_CO that best allows a single gas-to-dust ratio (delta_GDR) to describe each system. This approach remains sensitive to CO-dark envelopes of H2 surrounding molecular clouds. In M 31, M 33, and the LMC we find alpha_CO \approx 3-9 M_sun pc^-2 (K km s^-1)^-1, consistent with the Milky Way value within the uncertainties. The two lowest metallicity galaxies in our sample, NGC 6822 and the SMC (12 + log(O/H) \approx 8.2 and 8.0), exhibit a much higher alpha_CO. Our best estimates are \alpha_NGC6822 \approx 30 M_sun/pc^-2 (K km s^-1)^-1 and \alpha_SMC \approx 70 M_sun/pc^-2 (K km s-1)-1. These results are consistent with the conversion factor becoming CO a strong function of metallicity around 12 + log(O/H) \sim 8.4 - 8.2. We favor an interpretation where decreased dust-shielding leads to the dominance of CO-free envelopes around molecular clouds below this metallicity.

MorphoGraphX: A platform for quantifying morphogenesis in 4D

Abstract: Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX ( www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth.

Dopaminergic A10 neurones are involved in cognitive functions

Abstract: Delayed response tasks are widely considered to be particularly sensitive in demonstrating cognitive deficits after lesions of the prefrontal cortex in all species of mammals1. In rodents, these deficits are usually tested in a T-maze and are more pronounced after lesion of the anterior part of the striatum than after prefrontal cortex ablation2. In effect, the striatum is capable of assuming cortical functions either when the prefrontal cortex is poorly developed as in the lower mammals3 or immature as in the early life of primates4. The prefrontal cortex and anterior striatum—the so-called prefrontal system5—are functionally and anatomically related. The prefrontal area specifically involved in delayed alternation6 receives projections from the mediodorsal thalamic nucleus (MD)7 and sends axons to the anterior striatum as well as to the MD3,7. Recently, a detailed anatomical study of the connections of the prefrontal system revealed the existence of important projections from the mesencephalic dopaminergic A10 neurones and the mediodorsal nucleus that converge on the prefrontal cortex8. Axons of the A10 system also project to the anterior part of the striatum9,10. The influence of dopaminergic A10 neurones on frontal lobe functions remains obscure, but some observations concerning the behavioural, pharmacological and biochemical effects of neuroleptics and psychostimulants have supported the idea that these dopaminergic neurones could have a role in the pathogenesis of schizophrenia 11–13. Furthermore, the major symptoms observed in schizophrenic patients such as cognitive and attention disturbances have been attributed to a dysfunction of both prefrontal cortex and striatum14–16. Thus, in addition to their anatomical connections, the dopaminergic A10 neurones may be functionally related to the prefrontal cortex and striatum. These data encouraged us to investigate whether A10 neurones are functionally related to the prefrontal system and in particular if they are involved in cognitive processes measured in a delayed alternation task. We demonstrate here that selective lesions of dopaminergic A10 neurones in the rat produce a severe and specific impairment in retention of delayed alternation. On anatomical and behavioural grounds the dopaminergic A10 system could therefore be considered as a rather better indicator of frontal system function than the mediodorsal thalamic nucleus.