Differentiation of Human Adipose-Derived Stem Cells into “Brite” (Brown-in-White) Adipocytes

It is well established now that adult humans possess active brown adipose tissue (BAT) which represents a potential pharmacological target to combat obesity and associated diseases. Moreover thermogenic brown-like adipocytes (“brite adipocytes”) appear also in mouse white adipose tissue (WAT) upon β3-adrenergic stimulation. We had previously shown that human multipotent adipose-derived stem cells (hMADS) are able to differentiate into cells which exhibit the key properties of human white adipocytes, and then to convert into functional brown adipocytes upon PPARγ activation. In light of a wealth of data indicating that thermogenic adipocytes from BAT and WAT have a distinct cellular origin, we have characterized at the molecular level UCP1 positive hMADS adipocytes from both sexes as brite adipocytes. Conversion of white to brown hMADS adipocytes is dependent on PPARγ activation with rosiglitazone as the most potent agonist and is inhibited by a PPARγ antagonist. In contrast to mouse cellular models, hMADS cells conversion into brown adipocytes is weakly induced by BMP7 treatment and not modulated by activation of the Hedgehog pathway. So far no primary or clonal precursor cells of human brown adipocytes have been obtained that can be used as a tool to develop therapeutic drugs and to gain further insights into the molecular mechanisms of brown adipogenesis in humans. Thus hMADS cells represent a suitable human cell model to delineate the formation and/or the uncoupling capacity of brown/brite adipocytes that could help to dissipate caloric excess intake among individuals

Self assemblies of amphiphilic cyclodextrins

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Lipid Lateral Segregation driven by Diacyl Cyclodextrin Interactions at the Membrane Surface

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Solvent-free chemo-enzymatic synthesis of fatty acyl-β-cyclodextrin

International audienceLipase-catalyzed transesterifications were carried out without solvent and in mild conditions on permethylated β-cyclodextrins derivatives to obtain lipidyl-cyclodextrin, a new class of amphiphilic compounds with expected auto-assembly properties. Good conversion rate, of 6I-(N-hydroxyethylsuccinamido)-6I-deoxy-2I, 3I-di-O-methyl-hexakis (2II–VII,3II–VII,6II–VII-tri-O-methyl) cyclomaltoheptaose were obtained by using lipozyme as catalyst. Critical Aggregation Concentrations of these new derivatives of amphiphilic cyclodextrins (5.10−3 and 5.10−4 M) are in favor of an auto-association behavior. Finally, NMR experiments were carried out to evaluate the self-assembly of the compounds in water. The resulting supramolecular aggregates have potential to be used as nano-carriers for drug

Enzymatic catalysis in presence of cyclodextrins

International audienceCyclodextrins are able to interact in biocatalysis reaction. Their effects as solubilizing agents, inhibitor blocking agents and chiral selectors are well documented and they also interact before the enzyme-catalyzed reaction. Indeed, they have lyo-protectant effect for enzyme in organic medium biocatalysis and they participate in the refolding of inactive enzymes to regain their active form

Dimerization of xanthene dyes in water: Experimental studies and molecular dynamic simulations

1-D and 2-D NMR experiments and molecular dynamics simulations have been performed to study the dimerization process of two laser dyes namely Rodamine 6G and Pyronine 6G in water. Two possible stacked dimer structures have been evidenced, and the agreement between experimental and theoretical results is very good. The role of dispersive and electrostatic forces in the dimerization mechanism is discussed. This analysis allows us to suggest some chemical modifications on xanthene dyes to prevent such dimerization. On this basis, a new synthesized rhodamine is described which does not exhibit any dimerization phenomenon in a large range of concentrations

Functionalized cyclodextrins as biomimetic materials to degrade nerve agents

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Functionalized cyclodextrins as biomimetic materials to degrade nerve agents

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