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.

Astrophysical implications of the binary black hole merger gw150914

Abstract: The discovery of the gravitational-wave source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black-hole systems that inspiral and merge within the age of the Universe. Such black-hole mergers have been predicted in two main types of formation models, involving isolated binaries in galactic fields or dynamical interactions in young and old dense stellar environments. The measured masses robustly demonstrate that relatively "heavy" black holes (≳25M⊙) can form in nature. This discovery implies relatively weak massive-star winds and thus the formation of GW150914 in an environment with metallicity lower than ∼1/2 of the solar value. The rate of binary black-hole mergers inferred from the observation of GW150914 is consistent with the higher end of rate predictions (≳1Gpc−3yr−1) from both types of formation models. The low measured redshift (z∼0.1) of GW150914 and the low inferred metallicity of the stellar progenitor imply either binary black-hole formation in a low-mass galaxy in the local Universe and a prompt merger, or formation at high redshift with a time delay between formation and merger of several Gyr. This discovery motivates further studies of binary-black-hole formation astrophysics. It also has implications for future detections and studies by Advanced LIGO and Advanced Virgo, and gravitational-wave detectors in space.

Dendritic release of dopamine in the substantia nigra

Abstract: Dopamine can be released in the substantia nigra for the dendrites of nigrostriatal dopaminergic neurones, to be involved there in the self-regulation of the dopaminergic cells, to control the release of neurotransmitters from nigral afferent fibres and to influence the activity of nigral non-dopaminergic cells.

Astroglial metabolic networks sustain hippocampal synaptic transmission.

Abstract: Astrocytes provide metabolic substrates to neurons in an activity-dependent manner. However, the molecular mechanisms involved in this function, as well as its role in synaptic transmission, remain unclear. Here, we show that the gap-junction subunit proteins connexin 43 and 30 allow intercellular trafficking of glucose and its metabolites through astroglial networks. This trafficking is regulated by glutamatergic synaptic activity mediated by AMPA receptors. In the absence of extracellular glucose, the delivery of glucose or lactate to astrocytes sustains glutamatergic synaptic transmission and epileptiform activity only when they are connected by gap junctions. These results indicate that astroglial gap junctions provide an activity-dependent intercellular pathway for the delivery of energetic metabolites from blood vessels to distal neurons.

Angiotensin II type 1 receptor gene polymorphisms in human essential hypertension.

Abstract: We conducted the present study to determine whether the angiotensin II type I receptor (AT1) gene might be implicated in human essential hypertension by using case-control and linkage studies. The entire coding and 3' untranslated regions of the AT1 receptor gene (2.2 kb) were amplified by polymerase chain reaction and submitted to single-strand conformation polymorphism in 60 hypertensive subjects with a familial susceptibility. We identified five polymorphisms (T573-->C, A1062-->G, A1166-->C, G1517-->T, and A1878-->G). However, no mutations that alter the encoded amino acid sequence were detected. A case-control study performed on white hypertensive (n = 206; blood pressure, 168 +/- 16/103 +/- 9 mm Hg) and normotensive (n = 298; blood pressure, 122 +/- 10/75 +/- 9 mm Hg) subjects using three of five polymorphisms showed a significant increase in allelic frequency of C1166 in hypertensive subjects (0.36 versus 0.28 for normotensive subjects, chi 2 = 6.8, P C, A1878-->G) were similar in both groups. We performed a linkage study using the affected sib pair method and a highly polymorphic marker of the AT1 receptor gene. There was no evidence for linkage in 267 sib pairs analyzed from 138 pedigrees. These findings would be compatible with a common variant of the AT1 receptor imparting a small effect on blood pressure; further studies will be needed to address this possibility.