High-Throughput Analysis of Calcium Signalling Kinetics in Astrocytes Stimulated with Different Neurotransmitters

Astrocytes express a wide range of receptors for neurotransmitters and hormones that are coupled to increases in intracellular Ca2+ concentration, enabling them to detect activity in both neuronal and vascular networks. There is increasing evidence that astrocytes are able to discriminate between different Ca2+-linked stimuli, as the efficiency of some Ca2+ dependent processes – notably release of gliotransmitters – depends on the stimulus that initiates the Ca2+ signal. The spatiotemporal complexity of Ca2+ signals is substantial, and we here tested the hypothesis that variation in the kinetics of Ca2+ responses could offer a means of selectively engaging downstream targets, if agonists exhibited a “signature shape” in evoked Ca2+ response. To test this, astrocytes were exposed to three different receptor agonists (ATP, glutamate and histamine) and the resultant Ca2+ signals were analysed for systematic differences in kinetics that depended on the initiating stimulus. We found substantial heterogeneity between cells in the time course of Ca2+ responses, but the variation did not correlate with the type or concentration of the stimulus. Using a simple metric to quantify the extent of difference between populations, it was found that the variation between agonists was insufficient to allow signal discrimination. We conclude that the time course of global intracellular Ca2+ signals does not offer the cells a means for distinguishing between different neurotransmitters

Global Analysis of Dynamical Decision-Making Models through Local Computation around the Hidden Saddle

Bistable dynamical switches are frequently encountered in mathematical modeling of biological systems because binary decisions are at the core of many cellular processes. Bistable switches present two stable steady-states, each of them corresponding to a distinct decision. In response to a transient signal, the system can flip back and forth between these two stable steady-states, switching between both decisions. Understanding which parameters and states affect this switch between stable states may shed light on the mechanisms underlying the decision-making process. Yet, answering such a question involves analyzing the global dynamical (i.e., transient) behavior of a nonlinear, possibly high dimensional model. In this paper, we show how a local analysis at a particular equilibrium point of bistable systems is highly relevant to understand the global properties of the switching system. The local analysis is performed at the saddle point, an often disregarded equilibrium point of bistable models but which is shown to be a key ruler of the decision-making process. Results are illustrated on three previously published models of biological switches: two models of apoptosis, the programmed cell death and one model of long-term potentiation, a phenomenon underlying synaptic plasticity

Assessing lexical production in deaf signing children with the Boston Naming Test

A picture naming task, the Boston Naming Test, originally developed for spoken language, has been adapted to Italian Sign language in order to assess the vocabulary of Italian deaf signing children. Thirty deaf and thirty hearing children and adolescents (aged 6-14 years) participated in the study. In the deaf signing group, half of the children attended a bilingual school. Results show no significant differences between deaf and hearing participants in the number of correct responses provided, but do show interesting differences in the lexical accuracy observed for individual items and in error types reported for sign and speech. In the deaf group children attending a bilingual school performed significantly better than those who did not attend a bilingual programme

A developmental study on children's capacity to ascribe goals and intentions to others

The capacity to ascribe goals and intentions to others is a fundamental step in child cognitive development. The aim of the present study was to assess the age at which these capabilities are acquired in typically developing children. Two experiments were carried out. In the first experiment, 4 groups of children (age range = 3 years 2 months-7 years 11 months) were shown pictures representing hand-object interactions and asked what the individual was doing (what task) and why (why task). In the why task, observed handgrip could be either congruent with the most typical action performed with that object (e.g., to drink in the case of a mug) or corresponding to the act of putting away the object. In the second experiment, children saw pictures showing a handgrip either within a context suggesting the most typical use of the object or its being put away. Results showed that by 3-4 years, children are able to state the goal relatedness of an observed motor act (what understanding), whereas the ability to report the intention underlying it (why understanding) is a later and gradual acquisition, reaching a high performance by 6-7 years. These results, besides their intrinsic value, provide an important baseline for comparisons with studies on developmental disorders, also highlighting the relevance of distinguishing what and why understanding. © 2013 American Psychological Association

Microcystin-like toxins in different freshwater species of <i>Oscillatoria</i>

In January and September of 1989 and March 1990 blooms of Oscillatoria rubescens, Oscillatoria tenuis and Oscillatoria mougetii were found in Lake Simbirizzi and Lake Flumendosa in Sardinia, and in Lake San Puoto in the Lazio region of Italy. By using different extraction methods and HPLC analysis, two microcystin-like toxins (RR-like and YR-like), similar to some of the toxic compounds produced by the Cyanophycea Microcystis aeruginosa, were detected in these blooms

Multi-matrix assay of the first melatonergic antidepressant agomelatine by combined liquid chromatography-fluorimetric detection and microextraction by packed sorbent

A rapid and reliable analytical method has been developed to quantify the melatonergic antidepressant agomelatine in three matrices, and namely saliva, plasma and dried blood spots. The method is based on the use of liquid chromatography with fluorimetric detection exploiting the native fluorescence of agomelatine. For saliva and plasma samples an original microextraction by packed sorbent procedure was implemented obtaining satisfactory extraction yield of the analyte (always higher than 89%) and a good clean-up of the matrices. On the contrary, agomelatine was extracted from dried blood spots by suitable solvent microwave-assisted extraction and injected into chromatographic system. Satisfactory results in terms of sensitivity, linearity, precision, selectivity and accuracy were obtained. Thus, the developed method seems to be suitable for therapeutic drug monitoring of depressed patients under agomelatine therapy

Virulence factors in <i>Vibrio alginolyticus</i> strains isolated from aquatic environments

In a microbiological monitoring carried out in various aquatic environment of Sardinia Island (Italy) Vibrio alginolyticus with different virulence phenotypes appeared widely spread. Hemolysis, hemoagglutination and protease production might be together particularly in strains isolated from polluted environments. Adherence capacities to two epithelial cells (Hep-2 and Caco-2) available in laboratory were widely spread in the examined bacterial strains. The adhesion degree was influenced by the utilized cellular clone. The lack of a correspondence between adhesion capacity and more traditional virulence tests do not permit its replacement at screening level