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Biomedical subjects

M Frasca

Publications and source records attributed to M Frasca.

13 recordsLinked to original sources
PubMed2005

A programmable electronic circuit for modelling CO2 laser dynamics.

We introduce a programmable electronic circuit implementing the rich dynamics of CO2 laser models. The design and the implementation of the circuit are accomplished by using a programmable analog device, which permits an experimental characterization of the laser dynamics. The experimental results shown in the paper demonstrate that the circuit exhibits homoclinic chaos typical of CO2 laser with feedback modulation of cavity losses. Moreover, experimental results showing that noise regularizes the dynamical time scales of the system are reported.

Journal Article↗
PubMed2004

A nonlinear circuit architecture for magnetoencephalographic signal analysis.

OBJECTIVES: The objective of this paper was to face the complex spatio-temporal dynamics shown by Magnetoencephalography (MEG) data by applying a nonlinear distributed approach for the Blind Sources Separation. The effort was to characterize and differ-entiate the phases of a yogic respiratory exercise used in the treatment of obsessive compulsive disorders. METHODS: The patient performed a precise respiratory protocol, at one breath per minute for 31 minutes, with 10 minutes resting phase before and after. The two steps of classical Independent Component Approach have been performed by using a Cellular Neural Network with two sets of templates. The choice of the couple of suitable templates has been carried out using genetic algorithm optimization techniques. RESULTS: Performing BSS with a nonlinear distributed approach, the outputs of the CNN have been compared to the ICA ones. In all the protocol phases, the main components founded with CNN have similar trends compared with that ones obtained with ICA. Moreover, using this distributed approach, a spatial location has been associated to each component. CONCLUSIONS: To underline the spatio-temporal and the nonlinearly of the neural process a distributed nonlinear architecture has been proposed. This strategy has been designed in order to overcome the hypothesis of linear combination among the sources signals, that is characteristic of the ICA approach, taking advantage of the spatial information.

Algorithms↗
PubMed2004

[Alveolar ridge augmentation by means of onlay grafts harvested from mandibular symphysis].

AIM: Prosthestic-implant rehabilitation in subjects partially, or totally, endentulous is the method of choice for the considerable advantages involved from an aesthetic as well as functional point of view, besides preventing the physiological reabsorption that is established in the edentulous area. However, it is necessary to have an adequate quantity, as well as quality, of bone in order to support the fixture and the masticating load, conditions that up to now could often prove inferior for various reasons. Such a randomized research programme was proposed, in order to increase the bone volume by means of grafted onlays in the mandibular/chin area, with implant positioning 6 months after the operation, as a valid solution to the prosthestic problems found in the bone deficiency area. METHODS: Twenty patients with partial edentulism in the incisor-canine area were chosen. They showed no signs of periodontal diseases, bruxism or parafunctions. They underwent an autogenesis bone graft with the bone being taken from the mandibular/chin area, with positioning of the implant 6 months after the first operation, thus obtaining an increased bone height of 5 to 7 mm. RESULTS: Check ups were carried out in the 1(st) week after surgery, once a month for the first 3 months and then every 6 months and showed a minimal degree of bone reabsorption and an excellent osteo-integrative process. CONCLUSION: The use of onlay autogenous bone, compared to the other methods for increasing bone volume, is a valid solution for prosthetic-implant rehabilitation in edentulous areas.

Adult↗
PubMed2004

[Antibacterial effect of Nd:YAG laser in periodontal pockets decontamination: a in vivo study].

AIM: Tha aim of this paper is to assess the effects in vivo of the Nd: Yag laser on gingival microflora in patients periodontally at risk. METHODS: An investigation has been carried out on 5 patients suffering from serious periodontal disease, with a sub-gingival check-up a week after the treatment. The selected patients presented either a relapse after the raising of a traditional flap, or showed acute phenomena and were, therefore, treated with a laser with the propedeutic intention of surgery; or they refused traditional surgical therapy or presented systematic pathologies that could not be included in the appropriate protocol. Pockets were chosen that had a probe depth of between 5-8 mm, an optic fibre probe was pushed as far as possible into the probe depth, for about 1 minute per site, 5 times, at 30 second intervals. The samples, taken in order to calculate bacteria colonies, were carried out before using the laser, immediately after and, again, 1 week later. RESULTS: All the sites showed a slight reduction in the quantity of colonies forming immediately after the Nd:Yag laser application, while a week later, only if clinical inflammation appeared to be resolved, the bacteria forming colonies seemed to be reduced. CONCLUSION: From this study it can be concluded that the use of the Nd:Yad laser represents, in mild and average periodontitis, a therapeutic aid to scaling and root planing and, in the same way, in serious periodontitis for traditional surgical therapy.

Humans↗
PubMed1997

[The onset of syndrome X in old age].

There is evidence that angina-like chest pain associated with normal coronary angiography (syndrome X) may appear in adult patients. We have reviewed the clinical documentation of all the patient aged 65 or more admitted to our hospital because of recent onset typical or atypical angina, who underwent an exercise tolerance test and coronary angiography. Exclusion criteria were ischaemic or valvular heart disease and significant arterial hypertension. The selection lead to a series of 11 patients (6 females, 5 males) aged 65-72 years (mean 69). The bicycle ergometric test was positive in 7 and negative or not diagnostic in 2 patients each. Thallium-201 scintigraphy (performed in 6 patients) revealed reversible perfusion defects in 4 and was equivocal in 2 patients. At coronary angiography 6 patients showed non obstructive lesions (range: 20-40%) and only 5 had normal findings: 2 of these patients showed gastro-intestinal disease which could be considered as possible trigger of chest pain. Thus only 3 patients fulfilled the criteria for a diagnosis of syndrome X. These were 2 females and 1 male and were followed-up for a minimum of 2 years. All were in good condition, with normal left ventricular function free of major cardiac events, although occasional chest pain was still present. We conclude that syndrome X may appear also in the elderly with the same clinical features already described in younger patients. The overall prognosis is good and symptoms are partially insensitive to standard therapy. The low incidence in the older age may be explained, in our series, also by the restricted criteria adapted to select the study population.

Age of Onset↗
PubMed1995

AIDS related information, attitudes and behaviours among Italian male young people.

In order to evaluate the AIDS related sources of information, knowledge, attitudes and behaviours among male young people it was filled in a multi-choice anonymous questionnaire by 2018 subjects, called for the first medical examination to Italian Navy and by 1348 recruits. The data from the latter group were used to make comparisons with our previous survey carried out in 1988. The most important sources of information on AIDS were mass media and school, on sexuality friends and family. AIDS awareness was greater among the high educated subjects and positively influenced by mass media and school as sources of information. In agreement with these data, knowledge was better about AIDS than about sexuality. Risk perception was positively influenced by the AIDS-related knowledge for called youth and a greater intolerance towards infected people was observed among the less educated and the less AIDS-aware subjects. On average 46% of the called up young men and 74% of recruits declared to be sexually active: among these, the mean age at the first sexual intercourse was 16, over 60% declared to have had multiple partners, over 30% unknown partners and over 30% didn't use condoms; 20% of called up and 38% of recruits indicated 2 or 3 risk behaviours. Factors determining sex-related risks were different according to the behaviour and the considered group. These results suggest that it is important for young people to be well informed about sex and AIDS before the beginning of sexual activity, if possible during compulsory school.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Infections in heart transplantations].

Infections are one of the most important problems in heart transplants recipients: they are responsible for half total mortality within one year after surgery and one third of mortality during the following period. Underlying medical illness of the host, lack of specific immunity, prior colonization are conditions that may contribute to infections after surgery: immunosuppression to contrast rejection or due to Cytomegalovirus (CMV) infection are other factors favoring infections. Lung infections are most frequent. During the first month after surgery microorganisms responsible are the same found in cardiosurgery patients, staphylococci and gram negative, and occasionally herpes simplex virus (ESV) reactivated infections occur. From the second to the sixth month most of the CMV and Toxoplasma infections occur, with some Pneumocystis and mycotic events. Both are so frequent that in a seronegative host a specific prophylaxis against CMV and Toxoplasma is regularly recommended. The very late period more than six month after surgery is characterized by common infections seen in any population, that may present in altered or more severe fashion due to immune suppression. Another late event is cryptococcal meningitis.

Disease Susceptibility↗
PubMed1993

[The onset of dilated cardiomyopathy in a female HIV-seropositive patient with a history of past peripartal myocarditis].

A case of a young woman with HIV-associated cardiomyopathy is reported. The patient had a history of peri-partum myocarditis, and underwent a blood transfusion during delivery. The very early cardiac manifestation of AIDS-related pattern in this case is underlined, since HIV cardiomyopathy usually develops in the late stage of the disease. Finally, the role of the virus in the etiology and pathogenesis of the myocarditis is discussed.

Adult↗
PubMed1981

Depression of myocardial function during acute pancreatitis.

The left ventricular function of 24 patients with acute pancreatitis was studied noninvasively using systolic time intervals. Seven of the 24 patients were reevaluated 4-40 days following the onset of acute symptoms. During the acute phase the PEP/LVET ratio was significantly prolonged to 0.470 +/- 0.031 and later declined to 0.376 +/- 0.017 (P less than 0.01). The convalescent value is similar to the low grade abnormality found in noncardiac alcoholics without pancreatitis (0.381 vs 0.312 in age-matched normals). Since serum electrolytes were normal, serum cardiac isoenzymes were not elevated and there was no evidence of volume depletion in the initial stages, the transient cardiac depression produced by acute pancreatitis may be mediated by the postulated myocardial depressant factor from the pancreas.

Acute Disease↗