Structure-function relationships of the polypyrimidine tract binding protein

Abstract.: The polypyrimidine tract binding protein (PTB) is a 58-kDa RNA binding protein involved in multiple aspects of mRNA metabolism including splicing regulation, polyadenylation, 3′end formation, internal ribosomal entry site-mediated translation, RNA localization and stability. PTB contains four RNA recognition motifs (RRMs) separated by three linkers. In this review we summarize structural information on PTB in solution that has been gathered during the past 7 years using NMR spectroscopy and small-angle X-ray scattering. The structures of all RRMs of PTB in their free state and in complex with short pyrimidine tracts, as well as a structural model of PTB RRM2 in complex with a peptide, revealed unusual structural features that provided new insights into the mechanisms of action of PTB in the different processes of RNA metabolism and in particular splicing regulatio

Virtual reality as a new approach to assess cognitive decline in the elderly

Brain aging is a natural process that leads to a change in cognitive functions. Mild Cognitive Impairment (MCI) is a condition in which a person has cognitive functions that are below normal for his age. However, these deficits are not pronounced enough to confirm for the diagnosis of dementia. It is therefore important to develop new ways to assess cognitive functions in the elderly. This would indeed lead to a better identification of the cognitive losses that are related to normal or pathological aging. The objective of this study was to investigate the relevance of virtual reality as a new evaluation approach in psychology. To do this, 10 elderly people with Mild Cognitive Impairment, and 20 elderly people without cognitive problems, were compared using tests of prospective memory that were presented in a traditional way and in virtual reality. The diagnosis of MCI was made using the Montreal Cognitive Assessment (MoCA). Significant differences between the two groups were noted in virtual reality. Nevertheless, no difference was observed between the two groups with the traditional task. A significant positive correlation between the virtual reality task and the MoCA, but not between the traditional task and the MoCA, was observed. An evaluative approach based on virtual reality seems more sensitive to cognitive impairment associated with aging than an approach based on traditional neuropsychological tests.

Internal Dust Correction Factors for Star Formation Rates Derived for Dusty \HII Regions and Starburst Galaxies

Star formation rates in galaxies are frequently estimated using the Balmer line fluxes. However, these can be systematically underestimated because dust competes for the absorption of Lyman continuum photons in the ionized gas. Here we present theoretical correction factors in a simple analytic form. T These factors scale as the product of the ionization parameter, ${\cal U}$, and the nebular O/H abundance ratio, both of which can now be derived from the observation of bright nebular line ratios. The correction factors are only somewhat dependent upon the photoelectron production by grains, but are very sensitive to the presence of complex PAH-like carbonaceous molecules in the ionized gas, providing that these can survive in such an environment.Comment: 13 pages, 1 figures, Accepted for publication in ApJ. (Feb 1, 2003

European ornithomimosaurs (Dinosauria, Theropoda) : an undetected record

Early Cretaceous ornithomimosaurian theropod dinosaurs have been reported from various localities in Asia, whereas they remain poorly represented and extremely rare in North America, Africa and Europe. So far, the only known European ornithomimosaur is Pelecanimimus from the Barremian of Spain. The recent discovery in southwestern France of a lignitic bone bed in Angeac, which has yielded several hundred ornithomimosaur bones, sheds new light on the ornithomimosaurian fossil record. Based on this new material, we re-evaluate here the systematic position of various isolated theropod bones from the Wealden of England, including historical taxa of uncertain affinities. Based on a unique combination of derived characters, Thecocoelurus and Valdoraptor are linked to the Angeac taxon but are considered to be nomina dubia. Valdoraptor from the Valanginian of West Sussex appears to be the oldest known ornithomimosaur together with the contemporaneous Nqwebasaurus from South Africa. Ornithomimosaurs were a common component of the Early Cretaceous European dinosaur fauna. Their presence in Spain, France and England further strengthens the palaeobiogeographic affinities of the European fossil biota with that of Asia during this period

An Analytical Approach to Neuronal Connectivity

This paper describes how realistic neuromorphic networks can have their connectivity properties fully characterized in analytical fashion. By assuming that all neurons have the same shape and are regularly distributed along the two-dimensional orthogonal lattice with parameter $\Delta$, it is possible to obtain the accurate number of connections and cycles of any length from the autoconvolution function as well as from the respective spectral density derived from the adjacency matrix. It is shown that neuronal shape plays an important role in defining the spatial spread of network connections. In addition, most such networks are characterized by the interesting phenomenon where the connections are progressively shifted along the spatial domain where the network is embedded. It is also shown that the number of cycles follows a power law with their respective length. Morphological measurements for characterization of the spatial distribution of connections, including the adjacency matrix spectral density and the lacunarity of the connections, are suggested. The potential of the proposed approach is illustrated with respect to digital images of real neuronal cells.Comment: 4 pages, 6 figure

Pyrene-functionalized Foldamer: Structural Impact and Recognition Properties supported by Donor-Acceptor Interactions

An electroactive and luminescent foldamer based on an oligopyridine biscarboxamide skeleton was synthesized and characterised. Its conformation in the solid state proved to be strongly affected by the peripheral pyrene units. The latter also endow the target derivative with recognition abilities toward electron-withdrawing molecules, which allow tuning of the spectroscopic properties of the foldamer

A New 2D Interaction-based Method for the Behavioral Analysis of Instrumental Activities of Daily Living

In neuropsychology, many computerized solutions have been proposed in order to assess patients’ functioning in activities of daily living, via realistic interactive simulation. In this context, most developed systems are based on simple devices, real time 2D interaction, and monoscopic 3D computer graphics environment. Behavioral analysis has drawn the interest of many domains, such as neuropsychology, ergonomics, web design, or virtual reality. However, advances on this topic remains fragmented in their respective areas. Thus, in computerized solutions applied to neuropsychology, the behavioral analysis does not take into account the data from interaction. The potential interest of computerized solutions is hence underexploited. In this paper, we propose a transdisciplinary solution, based on a finer analysis of 2D interaction data, such as stop duration. This method could reveal interesting aspects of users’ behaviors

Mid-Infrared Emission Features in the ISM: Feature-to-Feature Flux Ratios

Using a limited, but representative sample of sources in the ISM of our Galaxy with published spectra from the Infrared Space Observatory, we analyze flux ratios between the major mid-IR emission features (EFs) centered around 6.2, 7.7, 8.6 and 11.3 microns, respectively. In a flux ratio-to-flux ratio plot of EF(6.2)/EF(7.7) as a function of EF(11.3)/EF(7.7), the sample sources form roughly a $\Lambda$-shaped locus which appear to trace, on an overall basis, the hardness of a local heating radiation field. But some driving parameters other than the radiation field may also be required for a full interpretation of this trend. On the other hand, the flux ratio of EF(8.6)/EF(7.7) shows little variation over the sample sources, except for two HII regions which have much higher values for this ratio due to an ``EF(8.6\um) anomaly,'' a phenomenon clearly associated with environments of an intense far-UV radiation field. If further confirmed on a larger database, these trends should provide crucial information on how the EF carriers collectively respond to a changing environment.Comment: 16 pages, 1 figure, 1 table; accepted for publication in ApJ Letter