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Biomedical subjects

Mariateresa Tedesco

Publications and source records attributed to Mariateresa Tedesco.

5 recordsLinked to original sources
PubMed2006

An automated microdrop delivery system for neuronal network patterning on microelectrode arrays.

The aim of this work is to present a new technique for defining interconnected sub-populations of cultured neurons on microelectrode arrays (MEAs). An automated microdrop delivery technique allows to design and realize spatially distributed neuronal ensembles by depositing sub-nanoliter volumes of adhesion molecules in which neurons grow and develop. Electrophysiological tests demonstrate that functionally interconnected clusters are obtained and experimental results (both spontaneous and stimulus evoked activity recordings) attesting the feasibility of the proposed approach are presented. By means of the automated system, different and specific architectures can be easily designed and functionally studied. In the presented system the speed of drop deposition is about 30 drops/min; the mean diameter is 147 microm; typical cell survival time is 4-5 weeks. By changing drop size and spacing, investigations about how the network dynamics is related to the network structure can be systematically carried out.

Age Factors↗
PubMed2006

Dissociated cortical networks show spontaneously correlated activity patterns during in vitro development.

In vitro cultured neuronal networks coupled to microelectrode arrays (MEAs) constitute a valuable experimental model for studying changes in the neuronal dynamics at different stages of development. After a few days in culture, neurons start to connect each other with functionally active synapses, forming a random network and displaying spontaneous electrophysiological activity. The patterns of collective rhythmic activity change in time spontaneously during in vitro development. Such activity-dependent modifications play a key role in the maturation of the network and reflect changes in the synaptic efficacy, fact widely recognized as a cellular basis of learning, memory and developmental plasticity. Getting advantage from the possibilities offered by the MEAs, the aim of our study is to analyze and characterize the natural changes in dynamics of the electrophysiological activity at different ages of the culture, identifying peculiar steps of the spontaneous evolution of the network. The main finding is that between the second and the third week of culture, the network completely changes its electrophysiological patterns, both in terms of spiking and bursting activity and in terms of cross-correlation between pairs of active channels. Then the maturation process can be characterized by two main phases: modulation and shaping in the synaptic functional connectivity of the network (within the first and second week) and general moderate correlated activity, spread over the entire network, with connections properly formed and stabilized (within the fourth and fifth week).

Action Potentials↗
PubMed2006

Nickel differentially affects NMDA receptor channels in developing cultured rat neurons.

Nickel (Ni(2+)) is a transition metal that exerts multiple and complex effects on N-methyl-d-aspartate (NMDA) channels. In both HEK293 cells and Xenopus laevis oocytes expressing recombinant NMDA receptors, Ni(2+) (<100 microM) caused a potentiation of NR2B-containing channels but a voltage-independent inhibition in those containing NR2A. We took advantage of this different response to investigate the developmental switch between NR2B and NR2A subunits in neonatal rat cerebellar granule cells up to 16 days in vitro (DIV) and in rat embryo cortical neurons up to 35 DIV. In both cultures, the effect of Ni(2+) on the NMDA current gradually changed from potentiating to inhibitory with progressing DIV, and the decline of potentiation correlated well with the decrease in sensitivity for the NR2B specific antagonist ifenprodil. Dose-dependent experiments confirmed that Ni(2+) has a different effect in younger cultures with respect to older ones, in agreement with an increase of the percentage of NR2A-containing receptors. The developmental switch occurred within the first 5 DIV in cerebellar granule cells and after 20 DIV in cortical neurons. All these data indicate that Ni(2+) is a suitable marker for the identification of NR2A and NR2B native channel subunits and can be used to trace the development of NMDA receptor composition.

Analysis of Variance↗
PubMed2005

Imaging and elasticity measurements of the sarcolemma of fully differentiated skeletal muscle fibres.

This study aimed to describe the three-dimensional structure and the elastic properties of the sarcolemma of adult, fully differentiated, skeletal muscle fibres combining Atomic Force Microscopy (AFM) and optical microscopy. Single fibres were enzymatically dissociated from Flexor Digitorum Brevis of adult mice and were maintained in culture up to 3 weeks. On the sixth day after dissociation, the upper surface of intact fibres, either alive in solution or fixed and kept in solution or fixed and exposed in air, was analysed with AFM. The most prominent features in AFM images were periodic transversal foldings with an interval that corresponded to the sarcomere length. More detailed analysis of the topography profile showed that the depth in the folding decreased with increasing sarcomere length and that the crests of the foldings corresponded to the Z-lines. Minor periodic structures could be detected in the valleys between the major foldings. AFM images also showed deep depressions on the sarcolemma likely corresponding to openings of T tubules and caveolae. Two-dimensional elasticity maps were obtained using AFM as an indenter and showed that the crests of the transversal foldings correspond to higher stiffness regions. This study provides the first complete three-dimensional topography and mechanical characterization of intact, living skeletal muscle fibres and might form the basis for further investigations aimed to compare healthy and dystrophic muscles.

Animals↗