Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

The Quijote Simulations

Abstract: The Quijote simulations are a set of 44,100 full N-body simulations spanning more than 7000 cosmological models in the hyperplane. At a single redshift, the simulations contain more than 8.5 trillion particles over a combined volume of 44,100 each simulation follows the evolution of 2563, 5123, or 10243 particles in a box of 1 h −1 Gpc length. Billions of dark matter halos and cosmic voids have been identified in the simulations, whose runs required more than 35 million core hours. The Quijote simulations have been designed for two main purposes: (1) to quantify the information content on cosmological observables and (2) to provide enough data to train machine-learning algorithms. In this paper, we describe the simulations and show a few of their applications. We also release the petabyte of data generated, comprising hundreds of thousands of simulation snapshots at multiple redshifts; halo and void catalogs; and millions of summary statistics, such as power spectra, bispectra, correlation functions, marked power spectra, and estimated probability density functions.

Photocatalytic Carbon Dioxide Reduction with Rhodium‐based Catalysts in Solution and Heterogenized within Metal–Organic Frameworks

Abstract: The first photosensitization of a rhodium-based catalytic system for CO2 reduction is reported, with formate as the sole carbon-containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H2-storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post-synthetic linker exchange, and characterization of a new metal–organic framework (MOF) Cp*Rh@UiO-67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF-based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of ∼10 % molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H2. There is no precedent for a MOF catalyzing the latter reaction so far.

Transient ciliogenesis involving Bardet-Biedl syndrome proteins is a fundamental characteristic of adipogenic differentiation

Abstract: Bardet-Biedl syndrome (BBS) is an inherited ciliopathy generally associated with severe obesity, but the underlying mechanism remains hypothetical and is generally proposed to be of neuroendocrine origin. In this study, we show that while the proliferating preadipocytes or mature adipocytes are nonciliated in culture, a typical primary cilium is present in differentiating preadipocytes. This transient cilium carries receptors for Wnt and Hedgehog pathways, linking this organelle to previously described regulatory pathways of adipogenesis. We also show that the BBS10 and BBS12 proteins are located within the basal body of this primary cilium and inhibition of their expression impairs ciliogenesis, activates the glycogen synthase kinase 3 pathway, and induces peroxisome proliferator-activated receptor nuclear accumulation, hence favoring adipogenesis. Moreover, adipocytes derived from BBS-patients' dermal fibroblasts in culture exhibit higher propensity for fat accumulation when compared to controls. This strongly suggests that a peripheral primary dysfunction of adipogenesis participates to the pathogenesis of obesity in BBS.

Influence of Angiotensin II Type 1 Receptor Polymorphism on Aortic Stiffness in Never-Treated Hypertensive Patients

Abstract: Several clinical and experimental studies have suggested a significant role of angiotensin II in the development of alterations of small and large arteries. The present study was designed to assess the contribution of polymorphism (corresponding to an A1166-->C transversion) of the angiotensin II type 1 receptor (AT1) gene to aortic stiffness. One hundred thirty-four never-treated hypertensive patients were included in the study. Aortic distensibility was evaluated by measuring carotid-femoral pulse wave velocity. Age, systolic and diastolic pressure, and metabolic parameters were similar in the three genotypes. Pulse wave velocity was 11.4 +/- 2.5 m/s in AT1 AA homozygotes, 12.5 +/- 3.2 m/s in AC heterozygotes, and 14.7 +/- 4.0 m/s in CC homozygotes (P = .003, P < .001 after adjustment for age, blood pressure, and body mass index). Moreover, an interaction was found between AT1 genotype and the ratio of total to high-density lipoprotein cholesterol in terms of the development of aortic stiffness. Thus, a positive correlation was observed between the ratio of total to high-density lipoprotein cholesterol and pulse wave velocity in AC and CC (r = .42, P < .001) but not AA patients. These results suggest that the AT1 gene is involved in the development of aortic stiffness in hypertensive patients and could modulate the effects of lipids on large arteries.

Specific stimulation of in vitro maturation of mesencephalic dopaminergic neurones by striatal membranes.

Abstract: We have previously established that dissociated mesencephalic dopaminergic (DA) neurones from embryonic mouse differentiate in primary cultures and that their development is enhanced when they are grown in the presence of their target cells from the striatum1–3. The capacity of individual DA neurones to take up and synthesize 3H-DA was increased in co-culture. This phenomenon does not depend on the presence of glial cells because it also occurred in serum-free conditions in which glial development was largely impaired4. Therefore, striatal target neurones favour the maturation of afferent DA neurones. Diffusible or membrane-bound factors could be involved in this process. To test one of these possibilities, we have now examined the in vitro development of embryonic mesencephalic DA neurones exposed to striatal membranes isolated from postnatal mice at various ages. 3H-DA uptake was used as an index of maturation of the DA neurones5. We show that striatal membranes from 2- and 3-week-old animals stimulate the development of DA neurones. The finding that this effect was not seen with membranes from 1-week-old or adult animals suggests that a developmentally regulated membrane-bound ‘factor’is probably involved. This factor seems to be specific for the DA neurones.