Is decision-making impairment an endophenotype of anorexia nervosa?

BACKGROUND: Patients with anorexia nervosa (AN) show impaired decision-making ability, but it is still unclear if this is a trait marker (i.e., being associated with AN at any stage of the disease) or a state parameter of the disease (i.e., being present only in acutely ill patients), and if it has endophenotypic characteristics. The aim of this study was to determine the endophenotypic, and state- or trait-associated nature of decision-making impairment in AN. METHODS: Ninety-one patients with acute AN (A-AN), 90 unaffected relatives (UR), 23 patients remitted from AN (R-AN), and 204 healthy controls (HC) carried out the Iowa gambling task (IGT). Prospective valence learning (PVL) model was employed to distinguish the cognitive dimensions underlying the decision-making process, that is, learning, consistency, feedback sensitivity, and loss aversion. IGT performance and decision-making dimensions were compared among groups to assess whether they had endophenotypic (i.e., being present in A-AN, UR, and R-AN, but not in HC) and/or trait-associated features (i.e., present in A-AN and R-AN but not in HC). RESULTS: Patients with A-AN had lower performance at the IGT (p < 0.01), while UR, R-AN, and HC had comparable results. PVL-feedback sensitivity was lower in patients with R-AN and A-AN than in HC (p < 0.01). CONCLUSIONS: Alteration of decision-making ability did not show endophenotypic features. Impaired decision-making seems a state-associated characteristic of AN, resulting from the interplay between trait-associated low feedback sensitivity and state-associated features of the disease.

Insight on Chirality Encoding from Small Thiolated Molecule to Plasmonic Au@Ag and Au@Au Nanoparticles.

Chiral plasmonic nanomaterials exhibiting intense optical activity are promising for numerous applications. In order to prepare those nanostructures, one strategy is to grow metallic nanoparticles in the presence of chiral molecules. However, in such approach the origin of the observed chirality remains uncertain. In this work, we expand the range of available chiral plasmonic nanostructures and we propose another vision of the origin of chirality in such colloidal systems. For that purpose, we investigated the synthesis of two core-shell Au@Ag and Au@Au systems built from gold nanobipyramid cores, in the presence of cysteine. The obtained nanoparticles possess uniform shape and size and show plasmonic circular dichroism in the visible range, and were characterized by electron microscopy, circular dichroism, and UV-vis-NIR spectroscopy. Opto-chiral responses were found to be highly dependent on the morphology and the plasmon resonance. It revealed (i) the importance of the anisotropy for Au@Au nanoparticles and (ii) the role of the multipolar modes for Au@Ag nanoparticles on the way to achieve intense plasmonic circular dichroism. The role of cysteine as shaping agent and as chiral encoder was particularly evaluated. Our experimental results, supported by theoretical simulations, contrast the hypothesis that chiral molecules entrapped in the nanoparticles determine the chiral properties, highlighting the key role of the outmost part of the nanoparticles shell on the plasmonic circular dichroism. Along with these results, the impact of enantiomeric ratio of cysteine on the final shape suggested that the presence of a chiral shape or chiral patterns should be considered.

Simulating Plasmon Resonances of Gold Nanoparticles with Bipyramidal Shapes by Boundary Element Methods.

Computational modeling and accurate simulations of localized surface plasmon resonance (LSPR) absorption properties are reported for gold nanobipyramids (GNBs), a class of metal nanoparticle that features highly tunable, geometry-dependent optical properties. GNB bicone models with spherical tips performed best in reproducing experimental LSPR spectra while the comparison with other geometrical models provided a fundamental understanding of base shapes and tip effects on the optical properties of GNBs. Our results demonstrated the importance of averaging all geometrical parameters determined from transmission electron microscopy images to build representative models of GNBs. By assessing the performances of LSPR absorption spectra simulations based on a quasi-static approximation, we provided an applicability range of this approach as a function of the nanoparticle size, paving the way to the theoretical study of the coupling between molecular electron densities and metal nanoparticles in GNB-based nanohybrid systems, with potential applications in the design of nanomaterials for bioimaging, optics and photocatalysis.

On the Simulation of Two-dimensional Electronic Spectroscopy of Indole-containing Peptides.

A benchmark study of low-cost multiconfigurational CASSCF/CASPT2 schemes for computing the electronic structure of indole is presented. This facilitates the simulation of near-ultraviolet (UV) pump visible (VIS) probe (i.e. two-color) two-dimensional electronic spectra (2DES) of homo- and hetero-aggregates as well as for processing of multiple snapshots from molecular dynamics simulations. Fingerprint excited-state absorption signatures of indole are identified in a broad spectral window between 10 and 25 k cm-1 . The 18-24 k cm-1 spectral window which has no absorption of the monomer and noninteracting aggregates is ideally suited to embed charge-transfer signatures in stacked aggregates. The small peptide Trp-cage, containing a tryptophan and a tyrosine amino acids, having indole and phenol as side chains, respectively, serves to prove the concept. Clear charge-transfer signatures are found in the proposed spectral window for an interchromophore distance of 5 Å making near-UV pump VIS probe 2DES a suitable technique for resolving closely packed aggregates. We demonstrate that 2DES utilizing ultra-short pulses has the potential to resolve the nature of the spectroscopically resolved electronic states and that the line shapes of the excited-state absorption signals can be correlated to the polarity of the relevant states.