Biomedical subjects

M Mattia

Publications and source records attributed to M Mattia.

12 recordsLinked to original sources

PubMed2003

[Pharmacotherapy of generalized anxiety disorder: state of the art].

A large percentage of patients in primary care suffer from Generalized Anxiety Disorder (GAD). A task force of the Swiss GAD Society has reviewed the scientific literature and has developed treatment recommendations. Basic treatment, adjunctive treatment and therapy of specific problems like insomnia and comorbidities are differentiated. Newer antidepressants are recommended as basic treatment, especially venlafaxine and paroxetine, which are licensed for that indication.

Adolescent↗

PubMed2001

Optimization of intensity modulated radiation therapy: assessing the complexity of the problem.

Intensity modulated radiation therapy (IMRT) is one of the most innovative techniques in oncological radiotherapy, allowing to conform the dose delivery to the tumoral target, preserving the normal tissue. The high number of parameters involved in the IMRT treatment planning requires an automated approach to the beam modulation. Such optimization process consists in the search of the global minimum of a cost function representing a quality index for the treatment. The complexity of this task, has been analyzed with a statistical approach for three clinical cases of particular interest in IMRT. Our main result is that a cost function based on dose-volume constraints entails lower complexity of the optimization process, in terms of the choice of the parameters defining the cost function and in a smaller sensitivity to the initial conditions for the optimization algorithm.

Radiotherapy Dosage↗

PubMed2001

Implementation of neuromorphic systems: from discrete components to analog VLSI chips (testing and communication issues).

We review a series of implementations of electronic devices aiming at imitating to some extent structure and function of simple neural systems, with particular emphasis on communication issues. We first provide a short overview of general features of such "neuromorphic" devices and the implications of setting up "tests" for them. We then review the developments directly related to our work at the Istituto Superiore di Sanità (ISS): a pilot electronic neural network implementing a simple classifier, autonomously developing internal representations of incoming stimuli; an output network, collecting information from the previous classifier and extracting the relevant part to be forwarded to the observer; an analog, VLSI (very large scale integration) neural chip implementing a recurrent network of spiking neurons and plastic synapses, and the test setup for it; a board designed to interface the standard PCI (peripheral component interconnect) bus of a PC with a special purpose, asynchronous bus for communication among neuromorphic chips; a short and preliminary account of an application-oriented device, taking advantage of the above communication infrastructure.

Computer Communication Networks↗

PubMed2000

Specific expression of soluble adenylyl cyclase in male germ cells.

The cAMP signaling pathway is an important mediator of extracellular signals in organisms from prokaryotes to higher eukaryotes. In mammals two types of adenylyl cyclase synthesize cAMP; a ubiquitous family of transmembrane isoforms regulated by G proteins in response to extracellular signals, and a recently isolated soluble enzyme insensitive to heterotrimeric G protein modulation. Using the very sensitive reverse transcription-polymerase chain reaction (RT-PCR), soluble adenylyl cyclase (sAC) expression is detectable in almost all tissues examined; however, Northern analysis and in situ hybridization indicate that high levels of sAC message are unique to male germ cells. Elevated levels of sAC mRNA are first observed in pachytene spermatocytes and expression increases through spermiogenesis. The accumulation of high levels of message in round spermatids suggests sAC protein plays an important role in the generation of cAMP in spermatozoa, implying possible roles in sperm maturation through the epididymis, capacitation, hypermotility, and/or the acrosome reaction.

Adenylyl Cyclases↗

PubMed2000

Efficient event-driven simulation of large networks of spiking neurons and dynamical synapses.

A simulation procedure is described for making feasible large-scale simulations of recurrent neural networks of spiking neurons and plastic synapses. The procedure is applicable if the dynamic variables of both neurons and synapses evolve deterministically between any two successive spikes. Spikes introduce jumps in these variables, and since spike trains are typically noisy, spikes introduce stochasticity into both dynamics. Since all events in the simulation are guided by the arrival of spikes, at neurons or synapses, we name this procedure event-driven. The procedure is described in detail, and its logic and performance are compared with conventional (synchronous) simulations. The main impact of the new approach is a drastic reduction of the computational load incurred upon introduction of dynamic synaptic efficacies, which vary organically as a function of the activities of the pre- and postsynaptic neurons. In fact, the computational load per neuron in the presence of the synaptic dynamics grows linearly with the number of neurons and is only about 6% more than the load with fixed synapses. Even the latter is handled quite efficiently by the algorithm. We illustrate the operation of the algorithm in a specific case with integrate-and-fire neurons and specific spike-driven synaptic dynamics. Both dynamical elements have been found to be naturally implementable in VLSI. This network is simulated to show the effects on the synaptic structure of the presentation of stimuli, as well as the stability of the generated matrix to the neural activity it induces.

Action Potentials↗

PubMed1999

Collective behavior of networks with linear (VLSI) integrate-and-fire neurons.

We analyze in detail the statistical properties of the spike emission process of a canonical integrate-and-fire neuron, with a linear integrator and a lower bound for the depolarization, as often used in VLSI implementations (Mead, 1989). The spike statistics of such neurons appear to be qualitatively similar to conventional (exponential) integrate-and-fire neurons, which exhibit a wide variety of characteristics observed in cortical recordings. We also show that, contrary to current opinion, the dynamics of a network composed of such neurons has two stable fixed points, even in the purely excitatory network, corresponding to two different states of reverberating activity. The analytical results are compared with numerical simulations and are found to be in good agreement.

Afferent Pathways↗

PubMed1993

Some effects of tonal fatiguing on spontaneous and distortion-product otoacoustic emissions.

Auditory fatiguing can be considered a suitable test to assess some cochlear mechanisms and diseases otherwise not easily detectable. Since spontaneous otoacoustic emissions (SOAEs) originate from active sources within the cochlea they show sensitive and early vulnerability to noise, displaying informative time-courses after overstimulation in the short (0-6 s) and in the long term (1-10 min) depending on the frequency of the fatiguing stimulus. Distortion product otoacoustic emissions too, in subjects with SOAEs, show interesting modifications after pure-tone exposure, detectable either on distortion product audiograms or in the growth functions. The modifications take place within a period of 5-7 minutes and strongly depend on the frequency of the fatiguing stimulus and on the closeness between SOAE and distortion product place. The data suggest that not only the interaction place between f1 and f2 has to be considered from a biomechanical and clinical point of view, but also the specific distortion product place on the cochlear partition.

Acoustic Stimulation↗

PubMed1989

[Acute accidental poisoning by mercury vapors in the home environment].

The authors report 2 cases of acute mercury intoxication due to accidental breakage of barometer on to a lit gas ring. Within 24-48 hours the subjects developed neurological, gastrointestinal and dermatological symptoms. A 24-hour urine sample contained 600 and 400 micrograms of mercury per liter respectively (reference value 0.1-6.9 micrograms/L); blood concentration of mercury was 130 and 100 micrograms per liter (reference value 1.7-9.9 micrograms/L). The patients were treated with penicillamine and daily excretion of mercury was monitored. The residual sources of pollution in the kitchen were identified and bonificated.

Accidents, Home↗

PubMed1986

Spontaneous otoacoustic emissions from normal human ears. Preliminary report.

The present paper resumes the results obtained from measurement of spontaneous otoacoustic emissions (SOAEs), in terms of rate of occurrence, frequency spectrum and intra- and intersubjective variability in 104 normal ears (52 subjects). SOAEs have been detected in 27 ears (26.0%) and in 16 subjects (30.8%); bilateral SOAEs have been observed in 11 subjects (68.8%). Frequencies of the strongest emissions ranged from 1 to 2 kHz (96.3%); amplitudes varied from 3 to 20 dB SPL above the background noise. Spectra were always very sharp and stable in frequency, less in amplitude. Present results agree well with the data available in literature.

Acoustic Stimulation↗

PubMedDate not supplied

[Work psychopathology and migration].

The author analyses the correlation between work psychopathology, migration and the role of the occupational physician. Migration was studied and analysed by many clinical psychiatrists, occupational psychiatrists and sociologists, who tried to investigate the possible consequences produced by this event on the psychological equilibrium, on social life and on working activities. It is unquestionable, according to the actual knowledge, that a strict correlation exists between work and psyche, or among the uneasiness of the work, cultural belonging and a psychopathology of the work. Work psycophatology appears to be the measurement of the repercussion of a dangerous work on human mental health and, consequently, could have a role in better adapting the man to his work. Therefore, in every work situation, the risk of a somatic or psycological, or even toxicological, pathology, must not be underevaluated. In a perspective of transcultural evaluation of the "migrant" worker who has to be introduced in a work environment, the knowledge of the "unspecific" health risks of the migrant, and of the cultural differences specifying the cultural value of work, becomes fundamental. Among the symptoms that require particular attention in the evaluation of a worker, the concept of fatigue is certainly fundamental and crucial. Consequently, it is necessary to safeguard the health of "the whole worker", not only acting on the physical and chemical occupational hazards, but also considering the relational and cultural risk factors.

Emigration and Immigration↗

PubMedDate not supplied

[Judgment on work capacity of a health worker with schizophrenia].

We show the case of a worker affected with schizophrenia who was declared by the psychiatrist fit to work. The "Medico Competente" on the contrary, on the basis of his studies and in particular on his deep knowledge of the features of the office and the place where that worker works, decides that he is not fit to do that job. This judgement is confirmed by the "ASL-Collegio Medico". The case we described emphasizes in a very strong way what is written in the item 17, paragraph 1, letter a of the D.Lgs 626/94, which extends the judgement of the fitness to work given by the "Medico Competente" even to the psychic sphere of the worker.

Adult↗

PubMedDate not supplied

[The psychosocial problems in a population of emigrant Italian workers].

The psycho-social problems of a group of 365 Italian emigrants to Switzerland, admitted to psychiatric hospitals, were studied. It was found that non professional subjects (housewives, unemployed, retired) and manual workers (builders, waiters, factory workers) were more likely to suffer from psycho-social disorders. Only 11.1% of those studied had received a secondary education, therefore it could be assumed that subjects having a low technical and cultural level were less prepared, psychologically, for their new situation and were thus more susceptible to psycho-social disorders. The most frequent diagnoses were found to be: affective disorders, alcohol addiction, opiate addiction and schizophrenia. The study revealed that emigrants ran a greater risk of first time admittance to psychiatric wards whereas the local population had a greater number of relapses. In conclusion it is stressed that assistance with an aim to improve work, social and relationship conditions and to integrate the emigrants into their host society can reduce some forms of psycho-social disorders.

Adult↗