Anatomical Connectivity Influences both Intra- and Inter-Brain Synchronizations

Recent development in diffusion spectrum brain imaging combined to functional simulation has the potential to further our understanding of how structure and dynamics are intertwined in the human brain. At the intra-individual scale, neurocomputational models have already started to uncover how the human connectome constrains the coordination of brain activity across distributed brain regions. In parallel, at the inter-individual scale, nascent social neuroscience provides a new dynamical vista of the coupling between two embodied cognitive agents. Using EEG hyperscanning to record simultaneously the brain activities of subjects during their ongoing interaction, we have previously demonstrated that behavioral synchrony correlates with the emergence of inter-brain synchronization. However, the functional meaning of such synchronization remains to be specified. Here, we use a biophysical model to quantify to what extent inter-brain synchronizations are related to the anatomical and functional similarity of the two brains in interaction. Pairs of interacting brains were numerically simulated and compared to real data. Results show a potential dynamical property of the human connectome to facilitate inter-individual synchronizations and thus may partly account for our propensity to generate dynamical couplings with others

Le manioc : une alternative à l'importation d'amidon au Cameroun. Recommandations d'actions pour le GAO du Nyong

Le Ministère de l'Agriculture du Cameroun, qui souhaite renforcer le développement de la filière racines et tubercules au Cameroun, a permis au GAO (Groupement des Associations - Organisations des femmes cultivatrices du Nyong) de réaliser le diagnostic d'un projet concernant l'installation d'une unité d'extraction d'amidon (capacité de traitement : 20 tonnes de racines par jour). Le projet formulé par le GAO devrait permettre, par la commercialisation de l'amidon, l'augmentation des revenus de plus de 15 000 familles dans les localités de Nguélémendouka et Angossas (province de l'Est) et de Kobdombo (province du Centre). Les visites de terrain ont permis de mieux apprécier la grande diversité des produits à base de manioc consommés au Cameroun (miondo, couscous, gari, fufu, bâton, bouilli). De plus, il est confirmé que pour chaque produit, certaines variétés sont privilégiées par les transformateurs. L'IRAD a collecté plus de 150 variétés dans les différents écosystèmes du pays et dispose des informations concernant leur utilisation. A ce jour, il n'existe aucune évaluation relative à la production d'amidon de manioc au Cameroun. Seuls, quelques petits producteurs d'amidon ont une connaissance des variétés les plus appropriées. 150 à 200 tonnes d'amidon importé sont utilisées mensuellement par les industries camerounaises. Les conditions d'accès à ce marché industriel pour l'amidon de manioc sont abordées. L'analyse des quelques données collectées sur place permet d'envisager de substituer une partie de l'amidon importé par une production locale. Les choix variétaux, les coûts de production et de transformation des racines, doivent être maîtrisés afin de respecter les conditions imposées par les industriels importateurs (prix, quantités, qualité, régularité). La diversité naturelle du manioc, adaptée aux conditions édapho - climatiques du bassin du Nyong, constitue, à elle seule, une ressource inestimable pour l'intensification de la culture du manioc. Le GAO a rassemblé les variétés locales et doit entreprendre une étude sur la productivité en amidon. Actuellement, le GAO n'est pas en situation d'approvisionner l'unité envisagée à court terme. Des solutions alternatives (diversification des produits du manioc) sont proposées pour fournir des revenus aux producteurs dans la période intermédiaire (défrichement, choix des variétés, multiplication du matériel végétal). La construction locale des matériels devant équiper les installations est privilégiée. Une attention toute particulière est portée à la formation des producteurs et transformateurs à leurs nouveaux métiers. Les aménagements proposés prennent en compte les besoins des populations concernées (distribution de l'eau, fourniture d'énergie électrique). Les résultats obtenus par le GAO montrent la vitalité d'une association dont les efforts méritent d'être renforcés par l'assistance technique de professionnels et appuyés par des apports financiers conséquents, véritables investissements pour le développement du bassin du Nyong. (Résumé d'auteur

Metabolic Activity and mRNA Levels of Human Cardiac CYP450s Involved in Drug Metabolism

Tissue-specific expression of CYP450s can regulate the intracellular concentration of drugs and explain inter-subject variability in drug action. The overall objective of our study was to determine in a large cohort of samples, mRNA levels and CYP450 activity expressed in the human heart.CYP450 mRNA levels were determined by RTPCR in left ventricular samples (n = 68) of explanted hearts from patients with end-stage heart failure. Samples were obtained from ischemic and non-ischemic hearts. In some instances (n = 7), samples were available from both the left and right ventricles. A technique for the preparation of microsomes from human heart tissue was developed and CYP450-dependent activity was determined using verapamil enantiomers as probe-drug substrates.Our results show that CYP2J2 mRNA was the most abundant isoform in all human heart left ventricular samples tested. Other CYP450 mRNAs of importance were CYP4A11, CYP2E1, CYP1A1 and CYP2C8 mRNAs while CYP2B6 and CYP2C9 mRNAs were present at low levels in only some of the hearts analyzed. CYP450 mRNAs did not differ between ischemic and non-ischemic hearts and appeared to be present at similar levels in the left and right ventricles. Incubation of verapamil with heart microsomes led to the formation of nine CYP450-dependent metabolites: a major finding was the observation that stereoselectivity was reversed compared to human liver microsomes, in which the R-enantiomer is metabolized to a greater extent.This study determined cardiac mRNA levels of various CYP450 isozymes involved in drug metabolism and demonstrated the prevalent expression of CYP2J2 mRNA. It revealed that cardiomyocytes can efficiently metabolize drugs and that cardiac CYP450s are highly relevant with regard to clearance of drugs in the heart. Our results support the claim that drug metabolism in the vicinity of a drug effector site can modulate drug effects

Observation of correlations up to the micrometer scale in sliding charge-density waves

High-resolution coherent x-ray diffraction experiment has been performed on the charge density wave (CDW) system K$_{0.3}$MoO$_3$. The $2k_F$ satellite reflection associated with the CDW has been measured with respect to external dc currents. In the sliding regime, the $2k_F$ satellite reflection displays secondary satellites along the chain axis which corresponds to correlations up to the micrometer scale. This super long range order is 1500 times larger than the CDW period itself. This new type of electronic correlation seems inherent to the collective dynamics of electrons in charge density wave systems. Several scenarios are discussed.Comment: 4 pages, 3 figures Typos added, references remove

Inter-Brain Synchronization during Social Interaction

During social interaction, both participants are continuously active, each modifying their own actions in response to the continuously changing actions of the partner. This continuous mutual adaptation results in interactional synchrony to which both members contribute. Freely exchanging the role of imitator and model is a well-framed example of interactional synchrony resulting from a mutual behavioral negotiation. How the participants' brain activity underlies this process is currently a question that hyperscanning recordings allow us to explore. In particular, it remains largely unknown to what extent oscillatory synchronization could emerge between two brains during social interaction. To explore this issue, 18 participants paired as 9 dyads were recorded with dual-video and dual-EEG setups while they were engaged in spontaneous imitation of hand movements. We measured interactional synchrony and the turn-taking between model and imitator. We discovered by the use of nonlinear techniques that states of interactional synchrony correlate with the emergence of an interbrain synchronizing network in the alpha-mu band between the right centroparietal regions. These regions have been suggested to play a pivotal role in social interaction. Here, they acted symmetrically as key functional hubs in the interindividual brainweb. Additionally, neural synchronization became asymmetrical in the higher frequency bands possibly reflecting a top-down modulation of the roles of model and imitator in the ongoing interaction

Cephalotaxus Alkaloids

International audienceCephalotaxus alkaloids represent a family of plant secondary metabolites known for60 years. Significant activity against leukemia in mice was demonstrated for extractsof Cephalotaxus. Cephalotaxine (CET) (1), the major alkaloid of this series was isolatedfrom Cephalotaxus drupacea species by Paudler in 1963. The subsequent discovery ofpromising antitumor activity among new Cephalotaxus derivatives reported by Chinese,Japanese, and American teams triggered extensive structure elucidation and biologicalstudies in this family. The structural feature of this cephalotaxane family relies mainly onits tetracyclic alkaloid backbone, which comprises an azaspiranic 1-azaspiro[4.4]nonaneunit (rings C and D) and a benzazepine ring system (rings A and B), which is linked by itsC3 alcohol function to a chiral oxygenated side chain by a carboxylic function alpha to atetrasubstituted carbon center. The botanical distribution of these alkaloids is limited tothe Cephalotaxus genus (Cephalotaxaceae). The scope of biological activities ofthe Cephalotaxus alkaloids is mainly centered on the antileukemic activity of homoharringtonine (HHT) (2), which in particular demonstrated marked benefits in thetreatment of orphan myeloid leukemia and was approved as soon as 2009 by EuropeanMedicine Agency and by US Food and Drug Administration in 2012. Its exact mechanismof action was partly elucidated and it was early recognized that HHT (2) inhibitedprotein synthesis at the level of the ribosome machinery. Interestingly, after a latencyperiod of two decades, the topic of Cephalotaxus alkaloids reemerged as a prolificsource of new natural structures. To date, more than 70 compounds have beenidentified and characterized. Synthetic studies also regained attention during thepast two decades, and numerous methodologies were developed to access the firstsemisynthetic HHT (2) of high purity suitable for clinical studies, and then high gradeenantiomerically pure CET (1), HHT (2), and analogs