Second-order nonlinear optical properties induced by thermal poling in photonic oxide glasses and transparent glass-ceramics

In recent years there has been a resurgence of interest in oxide glasses due to advances in lasers for information transport. Oxide glasses combine low cost of fabrication and good compatibility with silica glass fibers, which offer the opportunity for developing structures with nonlinear optical properties in integrated optical devices. The creation of an axial symmetry under thermal poling is currently necessary to induce Second-Order NonLinear (SONL) optical properties in glasses. A description of theoretical models which have been proposed for charge migration during thermal poling is presented. A review of SONL efficiencies which have been obtained for different glass compositions by this method is reported. Correlations between SONL properties and structural modifications under poling are also presented. Finally, we focus on the challenging fabrication of transparent glass-ceramic composites, especially when they are obtained by the precipitation of ferroelectric nanoparticle phases in the glassy matrix which adds the advantageous SONL properties of ferroelectric crystals

A short history of the 5-HT2C receptor: from the choroid plexus to depression, obesity and addiction treatment

This paper is a personal account on the discovery and characterization of the 5-HT2C receptor (first known as the 5- HT1C receptor) over 30 years ago and how it translated into a number of unsuspected features for a G protein-coupled receptor (GPCR) and a diversity of clinical applications. The 5-HT2C receptor is one of the most intriguing members of the GPCR superfamily. Initially referred to as 5-HT1CR, the 5-HT2CR was discovered while studying the pharmacological features and the distribution of [3H]mesulergine-labelled sites, primarily in the brain using radioligand binding and slice autoradiography. Mesulergine (SDZ CU-085), was, at the time, best defined as a ligand with serotonergic and dopaminergic properties. Autoradiographic studies showed remarkably strong [3H]mesulergine-labelling to the rat choroid plexus. [3H]mesulergine-labelled sites had pharmacological properties different from, at the time, known or purported 5-HT receptors. In spite of similarities with 5-HT2 binding, the new binding site was called 5-HT1C because of its very high affinity for 5-HT itself. Within the following 10 years, the 5-HT1CR (later named 5- HT2C) was extensively characterised pharmacologically, anatomically and functionally: it was one of the first 5-HT receptors to be sequenced and cloned. The 5-HT2CR is a GPCR, with a very complex gene structure. It constitutes a rarity in theGPCR family: many 5-HT2CR variants exist, especially in humans, due to RNA editing, in addition to a few 5-HT2CR splice variants. Intense research led to therapeutically active 5-HT2C receptor ligands, both antagonists (or inverse agonists) and agonists: keeping in mind that a number of antidepressants and antipsychotics are 5- HT2CR antagonists/inverse agonists. Agomelatine, a 5-HT2CR antagonist is registered for the treatment of major depression. The agonist Lorcaserin is registered for the treatment of aspects of obesity and has further potential in addiction, especially nicotine/ smoking. There is good evidence that the 5-HT2CR is involved in spinal cord injury-induced spasms of the lower limbs, which can be treated with 5-HT2CR antagonists/inverse agonists such as cyproheptadine or SB206553. The 5-HT2CR may play a role in schizophrenia and epilepsy. Vabicaserin, a 5-HT2CR agonist has been in development for the treatment of schizophrenia and obesity, but was stopped. As is common, there is potential for further indications for 5-HT2CR ligands, as suggested by a number of preclinical and/or genome-wide association studies (GWAS) on depression, suicide, sexual dysfunction, addictions and obesity. The 5-HT2CR is clearly affected by a number of established antidepressants/antipsychotics and may be one of the culprits in antipsychotic-induced weight gain

High gain / Broadband oxide glasses for next generation Raman amplifiers

L'intérêt pour l'amplification optique par effet Raman suscite un vif regain d'intérêt en raison de la nécessité d'accroître rapidement la bande passante dans le domaine des télécommunications, tant pour les liaisons longue distance que pour les réseaux locaux. Les verres inorganiques représentent des matériaux de choix de part leur réponse spectrale relativement large et la possibilité d'obtention aisée de fibres optiques. Le travail de thèse décrit les résultats obtenus sur différents verres oxydes qui ont été synthétisés et caractérisés en vue d'une utilisation comme milieu à gain Raman. Des mesures de diffusion raman spontanée, de gain Raman, d'indice de réfraction et d'absorption par une technique de déflection thermique ont été menées. Les réponses optiques ont été corrélées à la composition chimique et la structure du réseau vitreux. Une dépendance en fonction de la longueur d'onde de la réponse Raman a été mise en évidence ainsi qu'un phénomène de résonance lorsque la mesure est conduite près du front d'absorption. Deux familles de matériaux vitreux ont été explorées : des matrices vitreuses phosphates pour l'obtention de larges spectres de gain Raman et des matrices tellurites pour atteindre de forts coefficients d'amplification Raman. Les résultats obtenus lors de la thèse montrent que les matrices phosphates donnent effectivement accès à des largeurs de bande spectrale de gain Raman jusqu'à 40 tHz, ce qsui représente une augmentation d'un facteur 5 par rapport à SiO2. Les verres tellurites s'avèrent bien être de bons candidats pour des applications à fort gain Raman discret en atteignant des coefficients de gain Raman s'élevant à 50 fois ceux obtenus avec SiO2 à 1064 nm.BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocUnited StatesFranceUSF

Agonist/antagonist interactions with cloned human 5-HT(1A) receptors: Variations in intrinsic activity studied in transfected HeLa cells

The characteristics of 5-HT(1A)-recognition sites and receptor-mediated release of intracellular calcium were established in two transfected HeLa cell lines (HA 6 and HA 7) expressing different levels of human 5-HT(1A) receptors (about 3000 and 500 fmol/mg protein, Fargin et al. 1989; 1991; Raymond et al. 1989). The pharmacological profiles of the binding (determined with [3H]8-OH-DPAT) and the calcium response (measured using Fura-2) were clearly of the 5-HT(1A) type. Compounds such as 5-HT, 5-CT and 8-OH-DPAT acted as full agonists on the calcium response in both HeLa cell lines. In addition, methiothepin, pindolol, NAN 190 and SDZ 21 6-525 (Seiler et al. 1991) acted as silent and potent antagonists. Marked differences were observed in the responses mediated in the two cell lines. EC50values of agonists (particularly 5-HT, 5-CT, flesinoxan and 8-OH-DPAT) were higher in HA 7 cells (up to 80-fold) than in other 5-HT(1A) receptor models (e. g. inhibition of adenylate cyclase in calf hippocampus). Further, a variety of compounds (ipsapirone, buspirone, spiroxatrine, MDL73005) acted as agonists in HA 6 cells, whereas they behaved as silent antagonists in HA 7 cells (which express fewer receptors). By contrast, K(B) values for antagonists were comparable in HA 6 and HA 7 cells. The present data show that EC50values and intrinsic activity for a given drug are subject to large variations depending on the number of receptors expressed in the target tissue. The results obtained in HA 6 cells are comparable with respect to both potency and efficacy to those observed in calf or mouse hippocampus (inhibition of forskolin stimulated adenylate cyclase), whereas the results obtained in HA 7 cells are similar to those reported in mouse cortex (which was suggested to represent an atypical subtype of the 5-HT(1A) receptor). Since the agonist activity of a given compound at the same receptor can vary markedly, the present data show that intrinsic activity is not only ligand-dependent but also varies with the receptor-effector system studied. In addition, there seems to be no simple way to make predictions about intrinsic activity, since that feature is model-dependent