Biomedical subjects

M Pastorino

Publications and source records attributed to M Pastorino.

11 recordsLinked to original sources

PubMed2005

Morpho-functional alterations in testicular and nervous cells submitted to modelled microgravity.

Humans, as well as other life forms, have developed on earth under the terrestrial gravitational field. Questions concerning the effect of the gravity vector changes on the animal physiology have begun to emerge only in the last decades. Physiological alterations were observed during space flights, but space-born investigations at cellular levels are still very limited. Earth-bound simulations of low gravity obtained with the 3-dimensional Random Positioning Machine are extensively utilized to explore the effects of microgravity on cell function. After only a few minutes, weightlessness affected the cytoskeleton of lymphocytes, astrocytes, neurons and testicular cells, disorganizing microtubules, intermediate filaments and microfilaments. Cell division was impaired, mitochondria were disrupted and apoptotic phenomena occurred. Expression of proteins involved in transmembrane ion and water transport were also affected. In the Leydig cells the key enzymes (3beta- and 17beta-hydroxysteroid dehydrogenases) leading to testosterone synthesis were depressed. However, after 20 h of clinorotation the cells were able to synthesize heat shock proteins that initiated protection and recovery. The cytoskeleton was again well organized, normal mitosis occurred and the percentage of apoptotic cells returned to the range of 5%, similar to the control cultures. Ion and water transmembrane proteins and steroid dehydrogenases returned to normal levels. Long-term experiments showed that low gravity induced only transient alterations in the cultured cells, which were able to adapt to the gravity vector changes and to regain normal activity. These data may explain the physiological adaptation occurring in astronauts during and after space flights.

Animals↗

PubMed2004

Microgravity-induced alterations in cultured testicular cells.

Cultured STe cells (2n karyotype) from swine testis were submitted to simulated microgravity using a 3D Random Positioning Machine for 5 min., 15 min., 30 min., 1 h and 23 h. Sample processing included: histological characterization of cell types, immunohistochemical identification of (i) microtubules (a-tubulin), (ii) alkaline phosphates, (iii) 3 beta-hydroxy-steroid-dehydrogenase (3?-HSDH), and histochemical lipid analyses. After 5 min. simulated microgravity a slight microtubule disorganisation occurred, which increased dramatically with increasing microgravity duration. After 23 h microtubule arrays were completely disrupted. 3 beta-HSDH immunostaining was detectable only in one cell type: under control conditions and 5 min. into microgravity immunoreactivity was strong, but completely disappeared thereafter. Immunostaining intensity for alkaline phosphates, a good marker for myoid cells, decreased after 15 min. in microgravity.

3-Hydroxysteroid Dehydrogenases↗

PubMed2000

Masseter muscle activity during vestibular stimulation in man.

Experimental data report that vestibular afferents affect trigeminal system activity. The aim of this work was to evaluate whether static vestibular stimulation affects the excitability of trigeminal motoneurons in man. In order to assess this, voluntary EMG activity of masseter muscles as well as duration and latency of the early and late components of EMG exteroceptive silent period were evaluated while keeping the subject in vertical position and during 20 degrees static tilt. The experiments were performed on ten adult subjects with no orofacial, neurologic and otologic disorders. Each subject sat on a chair, which kept the complex head-jaw-neck-trunk and the limbs securely fixed, in order to minimize any interference due to the activation of somatosensory and proprioceptive afferents from these districts. The subjects were instructed to contract masseter muscles at 25% of their maximum bite force and the isometric force monitoring was used as visual feedback. Exteroceptive silent period (ESP) of masseter EMG was elicited by electrically stimulating the inferior inter-incisal gum. Results showed that static vestibular stimulation induced asymmetrical responses on voluntary masseter muscle activity, which was reduced to 70.3 +/- 16.1% (mean +/- S.D.) of the control value during ipsilateral tilt and increased to 128.8 +/- 13.0% during contralateral tilt. The duration of the early (ESP1) and late (ESP2) silent periods was also affected: during ipsilateral tilt ESP1 and ESP2 duration increased to 130.0 +/- 3.5% and to 122.1 +/- 2.1% of control, respectively; during contralateral tilt it was reduced to 76.8 +/- 1.2% and to 83.0 +/- 1.7% of control, respectively. On the contrary, changes in latencies were not significant. These data evidenced an asymmetrical effect exerted on trigeminal motor activity by static tilt. Since the influence of all receptors which could be activated by static tilt, except that arising from the macular ones, was minimized in this study, it is likely that the observed effects, induced by static tilt on masseter muscle activity, were of macular origin.

Adult↗

PubMed2000

Analytical SAR computation in a multilayer elliptic cylinder: the near-field line-current radiation case.

In this paper, a previously proposed analytical procedure for the computation of the specific absorption rate (SAR) inside a biological elliptic cylinder model is extended to the case in which the body is illuminated under near-field conditions. The elliptic model is made up of layers of different biological tissues and the source is constituted by a line-current distribution. The recursive procedure in which the field is expressed in terms of Mathieu function is modified to express the incident electromagnetic wave produced by the line current. The new procedure makes it possible to check and validate numerical solutions obtained by accurate numerical techniques for SAR prediction, under more realistic illumination condition.

Absorption↗

PubMed1999

Dose-intensive first-line chemotherapy with epirubicin and continuous infusion ifosfamide in adult patients with advanced soft tissue sarcomas: a phase II study.

This phase II study was designed to verify the activity and safety of an intensive epirubicin/ifosfamide schedule in untreated soft tissue sarcoma (STS) patients by using both the agents at the identified maximal tolerated doses. 39 adult patients were treated with epirubicin at 55 mg/m2, on days 1 and 2 (total dose per cycle 110 mg/m2) combined with ifosfamide at 2.5 g/m2 days 1-4 (total dose per cycle 10 g/m2), with equidose mesna uroprotection and G-CSF support. Treatment was given on an ambulatory basis, at 3-week intervals. The overall objective response (OR) rate was 59% (95% confidence interval, CI, 43-72%), with 5 complete responses (13%) at 18 partial responses (46%); 12 partial responders were rendered disease-free following surgery. The median survival time was 19 months, being 23 and 13 months, respectively, for responding and non-responding patients. The median time to response was 40 days (range 21-60). Treatment-related toxicity was overall acceptable. The OR of 59% was the highest ever reported in our consecutive studies in advanced STS, confirming that improved therapeutic efficacy can be obtained with intensified regimens in such a disease; both the response duration and survival were also longer. The observed activity proved to be interesting with regard to the high response rate in the lung (86%), as well as the proportion of patients rendered disease-free by early surgery after the achievement of a partial response (55%). Both these findings may be important in the multimodality approach to patients with lesions potentially resectable for cure.

Adult↗

PubMed1999

EM field prediction inside lossy multilayer elliptic cylinders for biological-body modeling and numerical-procedure testing.

In this paper, a biological model made up of a multilayer elliptic cylinder is considered. This canonical scattering problem is solved by a recursive procedure, which has been generalized to the case of lossy materials by using the analytical properties of Mathieu functions. Although it is a simplified model, this stratified configuration may simulate better than circular cylinders the local behavior of biological subsystems. In addition, it represents an effective tool for producing analytical data for testing direct-scattering numerical codes in biomedical applications and for the evaluation of reconstruction procedures in medical imaging.

Animals↗

PubMed1999

Analytic SAR computation in a multilayer elliptic cylinder for bioelectromagnetic applications.

The specific absorption rate (SAR) is usually considered as the basic quantity to derive the reference levels for the exposure of workers and general population. In this paper, we propose an analytical procedure for the SAR computation inside a biological elliptic cylinder model made up of layers of different biological tissues. The procedure makes it possible to obtain accurate SAR values in simplified models of biological subsystems, and it is also helpful to test numerical techniques to be used for more realistic models and to generate synthetic input data for diagnostic methodologies. For the assumed model, the calculation of the analytical solution has been obtained by generalizing a known procedure that deals only with lossless materials, and the model makes possible the calculation of the SAR for realistic human tissues. Various calculations prove the reliability of the technique.

Biophysical Phenomena↗

PubMed1997

Pudendal nerve somatosensory evoked potentials in probable multiple sclerosis.

Bladder dysfunctions are often observed in patients with multiple sclerosis (MS). In order to evaluate their sensitivity in detecting abnormalities in bladder central control pathways, pudendal nerve somatosensory evoked potentials (pSEPs) were recorded in 16 patients with clinically probable MS: six were affected by retention or urge incontinence, and ten were asymptomatic. Conventional visual, auditory and somatosensory evoked potentials were also recorded, and all of the patients underwent a urodynamic examination. Prolonged latency or the absence of pSEP cortical responses was found in eight of the ten asymptomatic patients, and in all of the symptomatic cases (87.5%). The urodynamic evaluation revealed abnormalities in 12 patients (75%). Our findings seem to indicate an early and frequent involvement of bladder control pathways in MS patients, as well as a high rate of subclinical disorders.

Adolescent↗

PubMed1997

Epidemiology of myasthenia gravis in northwestern Sardinia.

A previous epidemiological study on myasthenia gravis (MG) in Sardinia indicated a prevalence rate of 4.5 per 100,000 population and an incidence of 0.25 per 100,000 population in the period 1958-1986. This study, however, investigated the entire Sardinian population (about 1,500,000) and the reported rates are likely to be underestimated. Because the use of a very large population has been found to cause major bias in case finding, the present study was designed to overcome this bias by determining the prevalence and incidence of MG in a well-defined area of Northwestern Sardinia, with a population of about 270,000 (1991 census). Potential MG cases were ascertained using all possible medical sources. The diagnosis of MG was based on the clinical, neurophysiological and conventional pharmacological findings (Tensilon test, response to anticholinesterases). On prevalence day (December 31, 1994) 29 MG patients were living in the study area (17 women and 12 men). Since the total population on prevalence day was 268,926 (137,284 women and 131,642 men), the calculated prevalence was 11.1 per 100,000 population (12.4 women and 9.9 men). The present study shows that the risk of MG in Sardinia is higher than previously suggested. The risk, however, is not significantly different from that found in other comparable Italian and European areas. It contrasts with what has been found for other autoimmune diseases such as multiple sclerosis and insulin-dependent diabetes mellitus in Sardinians, both showing frequencies up to 3-5 times higher than in the rest of Italy.

Adolescent↗

PubMed1994

An electromagnetic imaging approach using a multi-illumination technique.

An approach to microwave imaging using a multi-illumination technique is proposed. The numerical solution is reached by a multi-illumination-angle multiview approach based on the moment method. The aim is to extend the application range of the Born approximation by utilizing a-priori information about a scatterer. The basic idea of the approach is outlined, and preliminary results are reported.

Bias↗

PubMed1991

Numerical algorithm for dielectric-permittivity microwave imaging of inhomogeneous biological bodies.

A two-dimensional microwave system is developed to explore the possibility of imaging the distribution of dielectric permittivity in an inhomogeneous biological body. A multiview approach is presented, which can notably improve the system's performance; it makes use of an illumination source that rotates jointly with the observation domain in which the scattered electric field is to be measured. The equation for inverse electromagnetic scattering is transformed into matrix form through the application of the moment method. A pseudoinversion algorithm is used to determine the distribution of the dielectric properties of the scattering body. A look-up table is devised to quickly form the final image. The results of some numerical simulations are reported to point out the capabilities and limitations of the method.

Algorithms↗