1,721,152 research outputs found
An allosteric model for the functional plasticity of olfactory chemoreceptors
No full textA simple allosteric model mey describe the relatively (a)specific behaviour of olphactory chemoreceptors (OCs) and their functional plasticity with a minimum number of parameters. Allosteric, heterotropic effectors are suggested as a possible cause of variable responses documented, in particular, in frog OCs
MULTI-AGENT SIMULATORS: FLEXIBLE TOOLS TO REPRODUCE COLLECTIVE BEHAVIORS I. the use of force-fields
No full textThis is the first part of a report on the use of a multi-agent simulator able to show the influence of various
types of environmental factors, in the form of force fields, on the collective behavior of a numerous population
of agents. The applications include a toy-model of the Big Bang theory, the structural changes induced on a
cell population and a longitudinal study of medical students’ training. As for qualitative simulations of complex,
collective behaviors, the multi-agent approach appears fully justified by its flexible and straightforward
implementation. However, a great enhancement of its heuristic power is foreseeable, due to the relatively easy
account even of sophisticated environmental effects and cooperative interactions
Expression Analysis In Vitro
No full textExpression analysis in vitro is a rapidly growing and constantly evolving field, based upon the use of a template of RNA, for a translation reaction, or of DNA, in a coupled transcription–translation system
The imagery effect on memorizing verbal information: an experimental approach
No full textImagery is a conscious, quasi-perceptive personal experience elicited by sensorial perceptions but not necessarily linked to them. Experimental tests of the imagery effect are possible since verbal stimuli can modulate the intensity of mental representation , and accurate statistical protocols can be designed to assess their importance in recognizing and memorizing words. This allows to use objective indicators of the multiple and complex phenomena accompanying/influencing any cognitive process
What can we learn by connecting neurons in a nanodevice?
No full textA brief overview of examples selected from the literature and concerning structural and functional properties
of neurons explored by systematic use of nanodevices is provided, in the aim to show that: i) the native
clustering ability of isolated neurons can be controlled and induced to form clusters of interconnected functional
units on appropriately engineered nanodevices; ii) the initiation of Synchronized Bursting Events (SBE)
by local chemical stimulation can be evidentiated in cultured neurons using Micro Electrode Arrays (MEA);
iii) the interactions among different cell types (cocultures) can be studied in compartimentalized microfluidic
platforms where different microenvironments are separated and let communicate through microchannels.
Over and above their intrinsic value, such exemplary cases inspired our own research projects on cocultures
of electrically excitable cells. Our main target are the mechanisms of axon-localized neuronal damage, as
arising in some rare neurodegenerative pathologies as well as in Amiothrophic Lateral Sclerosis (ALS). In this
frame, clarifying the sequence of events initiating the formation of structural interactions between neurons and
miocytes is mandatory, and even mimicking the Neuromuscolar junctions appears feasible
Simfit: A microcomputer software-toolkit for modelistic studies in biochemistry
No full textA software package suitable for personal computers and designed to handle simulation and fitting problems related to the study of biomolecules under pre-steady and steady state conditions is presented, and its overall architecture as well as the implemented algorithms illustrated. The peculiar features of the package are: (i) integrated capability of simulating dynamic models and fitting to them experimental data; (ii) handling of stiff problems; (iii) free use of algebraic as well as differential equations; (iv) objective comparison of models of different complexity. The above features are discussed through a number of examples taken from the direct experience of the authors in enzyme kinetics and ligand binding
PRIMARY STRUCTURES OF PROTEINS AS SPACE-DEPENDENT SIGNALS
No full textThis minireview is devoted to a scarcely populated but potentially quite interesting eld of computational biochemistry: the use of signal analysis methods to describe
protein sequences as mono-dimensional series. The protein sequences are described by means
of a vector of numerical variables that summarize their autocorrelation structures. Thus, the
simplest level of protein sequences description shifts from the pairwise alignment of structures
to a self-consistent numerical description of the single sequence. The main steps of the method can be summarized as follows: a)
use of hydrophobic code for primary structures; b) treatment of the hydrophobicity
distribution along the sequence like a time series, with the corresponding use of nonlinear signal
analysis techniques to underpin position-dependent properties of the hydrophobicity proles; c) adoption of a local approach for both inter-sequence (within homologous series
of proteins) comparisons and intra-sequence (among short patches along the same sequence)
analyses as a starting point for periodicity detection
Temperature acclimation modulates the oxygen binding properties of the Atlantic cod (Gadus morhua L.) genotypes - HbI*1/1, HbI*1/2, and HbI*2/2.
No full textThe influence of long-term acclimation temperatures in Atlantic cod (Gadus morhua) was studied by growth experiments carried out over a total of 272 individuals. The attention focused on the structural and functional modulation of the five electrophoretically distinguishable genotypes of cod hemoglobin (HbI*1/1, HbI*1/2, HbI*2/2, HbI*1/2b, and HbI*2/2b) and on the correlation with body length/weight. The main results can be summarized as follows. (1) Acclimation to lower (4 and 8 °C) and higher (12 and 15 °C) temperatures favors the expression of, respectively, more anodic and more cathodic hemoglobin components. (2) The optimal O2 transporting features are observed at 12 °C, as well as a saturation-dependent temperature dependence of O2 binding, which furthermore is strongly dependent upon the acclimation background. (3) The optimal growth condition for the three main genotypes (HbI*1/1, HbI*1/2, and HbI*2/2) is associated with T=12 °C. The overall results are consistent with the idea that environmental temperatures constitute a primary factor in the aggregation of individuals physiologically more than genetically homogeneous. This is fully confirmed by careful statistical analysis carried out over a subset of individuals for which the full set of structural (isoelectric focusing), functional (O2 binding), and growth data was available
MIGRAINE AND EPILEPSY: LOOKING FOR A COMMON PATHOPHYSIOLOGICAL MODEL
No full textThis contribution reports about the results gathered from in-silico experiments testing the feasibility of a research
program based upon a common pathophysiological mechanism for migraine and epilepsy. In a rst set of experiments,
the Electroencephalographic (EEG) signals from couples of corresponding electrodes in the two cerebral emispheres,
as well as from couples of continguous electrodes in the left and right emisphere, were systematically correlated. In
both cases, the existence of ordered distributions of activity patterns in the EEG signals from migranious and epileptic
subjects was qualitatively assessed. In a subsequent and crucial set of experiments, we were able to obtain some
spatially ordered and oscillating synchronization patterns of virtual neurons distributed over a bidimensional region,
by means of a multi-agent simulation environment (Netlogo). On the basis of such results, a further development
of our research program including the enrichment of the data set and the consideration of other powerful simulation
approaches, e.g. Articial Neural Network (ANN) or Genetic Algorithms (GA), seems in the good track of realizing
a realistic simulation of the Cortical Spreading Depression Waves, potentially useful even for clinical purposes
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