Biomedical subjects
Publications and source records attributed to G Peruzzi.
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The goal of the study was to characterize the changes in neurovegetative control of the circulation, attending the presumed physiological and psychological stress originated by the isolation and confinement typical of the living condition of space stations, as simulated in a ground based unit, using time and frequency domain analysis. As a secondary goal we sought to verify the implementation of real time data acquisition, for off line spectral analysis of R-R interval, systolic arterial pressure (by Finapres) and respiration (by PVF2 piezoelectric sensors). We addressed the cardiorespiratory and neurovegetative responses to standardized, simple stressors (active standing, dynamic and static handgrip) on the EXEMSI 92 crew, before, during and after the isolation period. On average the appropriate excitatory responses (to stand, dynamic and static handgrip) were elicited also in isolation and confinement. Active standing and small masses muscular exercises are easy to be performed in a confined and isolated environment and provide a valuable tool for investigating the adaptational changes in neural control mechanisms. The possibility there exists of using this time and frequency domain approach to monitor the level of performance and well being of the space crew in (quasi) real time.
Methylazoxymethanol (MAM)-induced microencephalic aged animals with reduced cortical mass and unmodified basal nucleus were used to study the relationship between cells that produce and cells that utilize NGF. Total cortical ChAT activity of MAM 2, 19 and 27 month old animals was reduced compared to their age-matched controls. To verify whether the reduction of enzyme activity can be ascribed to changes in or ablation of projecting neurons, we carried out immunohistochemical analysis of ChAT and low affinity NGF receptor (p75NGFR) in the basal nucleus of control and MAM-treated animals. ChAT and p75NGFR immunostaining of basal forebrain cholinergic neurons showed morphological changes in MAM animals, as revealed by cellular atrophy, reduced dendritic arborization and decreased staining intensity. In the cerebral cortex of microencephalic animals, reduced levels of NGF compared to controls were observed at all examined ages. These results suggest that MAM treatment induces long-lasting ablation of cortical NGF-synthesizing cells leading to reduced trophic support to basal forebrain cholinergic neurons, which might be responsible for the cellular atrophy observed in the basal nucleus.
Treatment of female Sprague-Dawley rats with 15 or 25 mg/kg (IP) of methylazoxymethanol acetate (MAM) at gestational day 15 (15 DG) resulted in a dose-dependent reduction of total brain weight of the adult offspring. When tested for spontaneous activity in a residential maze over a 23 hour period, those animals treated with the highest dose of MAM showed an increase in both locomotion and local activity during night hours without changes in the structure of behavior. Animals treated with 15 mg/kg of MAM showed no difference in activity compared to controls despite a significant reduction in brain weight.
The aim of this review is to provide a critical and concise discussion of present knowledge on the role of atrial natriuretic factor (ANF) in physiological as well as pathological pulmonary conditions. The lung contributes only to a small extent to the production of circulating ANF; on the other hand, the lung represents the major degrading site of the protein. Plasmatic ANF concentration increment during lung disease may therefore be due to a reduction in ANF plasma removal enzyme rather than to increased ANF production. Lung tissue shows more ANF receptor sites than any other organ. The effect of ANF on bronchial and pulmonary artery muscle lining is particularly evident. In fact ANF administration in asthmatic patients leads to bronchodilation comparable to dilation induced by salbutamol. Furthermore, elevated levels of circulating ANF seem to influence fluid redistribution through alveolar-capillary membrane leading to protein mobilization through the alveolar space. On the contrary, in the cardiomyopathic hamster ANF induces relevant guanylate cyclase activation before the animal has developed hemodynamic changes. Guanylate-cyclase activation may protect the lung through counteracting pulmonary edema formation, as shown by fluid reduction in alveolar spaces following pneumotoxic agents administration. This effect seems independent of natriuretic and hypotensive ANF effects.
Several neurophysiological studies have shown that electrical activation of afferent fibers of somatic nerves can evoke inhibitory or excitatory cardiovascular responses. The present investigation was undertaken to examine the effects induced by electrical stimulation of somatic nerves on cardiocirculatory and respiratory functions in anesthetized rabbits. Both low frequency stimulation and high frequency stimulation of afferent fibers of somatic nerves caused two distinct patterns of cardiocirculatory and respiratory reflex responses absolutely similar to those observed in our previous experiments on rabbits with dynamic and static exercise. The present findings do not support the existence in the somatic nerves of afferent fibers with cardiorespiratory effect having physiological functions different from that of producing cardiopulmonary adjustments to muscular activity.
A variant of Cigorraga's method, in order to eliminate communicant veins in lower limbs varix, is exposed. To localize and cut these communicants, two spatulas, one with rounded end and the other with semilunar and cutting end, are employed.
Most of the functional problems astronauts may suffer during and after long-term space missions are mainly associated with the reduction of the gravity force which causes a central fluid shift and a redistribution of the blood flow. Blood volume centralization induces a rapid increase in diuresis with elimination of consistent amounts of water and electrolytes which leads to a reduction of cardiac output, body fluid and to a hypodynamic state of the cardiovascular system. The effects of micro-gravity on skeletal and muscular systems are quite severe causing rapid bone demineralization, especially in the spine and lower extremities, and hypotrophy of the muscular masses. Micro-g also appears to determine cellular and molecular modifications with inhibition of the immune system, hematopoiesis and resistance to infections. Orthostatic intolerance, with feeling sick, instability and sometimes syncope, is characteristically observed after the return to earth due to a remarkable fluid shift in the lower part of the body and an acute reduction in blood flow to the brain. Physical exercise may play an important role among the countermeasures proposed to reduce most of the cardiovascular and musculo-skeletal effects of micro-g. Furthermore, micro-g offers many interesting prospects for the development of new technologies for the synthesis of biologically active substances for pharmacological use. Further severe limiting factors, for more prolonged manned space missions, are the so called "human factors" including psycho-emotional and social behaviour, especially regarding the future of astronauts after their return to earth.