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T Pozzo

Publications and source records attributed to T Pozzo.

42 records · Page 3Linked to original sources
PubMedDate not supplied

Effect of weightlessness on posture and movement control during a whole body reaching task.

Here are reported preliminary results of the "Synergy" experiment performed aboard the Russian orbital station "MIR" in July 1993 (Altair Mission). The experiment was carried out before, during, and after the space flight of two astronauts (S1 and S2). The duration of the flight was 21 days for S1 and 6 month for S2. The subjects were tested during preflight, inflight and postflight. The astronaut subjects were fixed on the ground by the feet. They were asked to pick up a box in front of them on the ground. Two velocities of movement and two distances of the target to be reached were tested. The movement of several small markers placed on the body was recorded on video tape. Results show that the shape of head and hand trajectories in the sagittal plane remains roughly the same during the flight in spite of the modification of mechanical constraints. Trajectory invariance does not result in joint angular displacement invariance. These data indicate that the planning of the movement takes place in terms of head and hand trajectories rather than joint rotations as it was previously suggested for simple arm reaching movement.

Adaptation, Physiological↗
PubMedDate not supplied

Arm end-point trajectories under normal and micro-gravity environments.

The purpose of the present experiment was to study the way in which the CNS represents gravitational force during vertical arm pointing movements. Movements in upward and downward directions were executed by two cosmonauts in normal-gravity and weightlessness. Analyses focused upon finger kinematics in the sagittal plane. In normal-gravity, downward direction movements showed smaller curvatures and greater relative times to peak velocity (AT/MT) when compared with upward direction movements. Data from the weightlessness experiments showed that whilst downward movements decreased their curvature during space flight, curvatures of upward movements changed slightly. Furthermore, AT/MT was modified during the first days in micro-gravity for both directions, recovering, however, to pre-flight values after 18 days in space. Results from the present study, provide evidence that gravitational force is centrally treated constituting an important component of the motor plan for vertical arm movements.

Aerospace Medicine↗
PubMedDate not supplied

Does the centre of mass remain stable during complex human postural equilibrium tasks in weightlessness?

In normal gravity conditions the execution of voluntary movement involves the displacement of body segments as well as the maintenance of a stable reference value for equilibrium control. It has been suggested that centre of mass (CM) projection within the supporting base (BS) is the stabilised reference for voluntary action, and is conserved in weightlessness. The purpose of this study was to determine if the CM is stabilised during whole body reaching movements executed in weightlessness. The reaching task was conducted by two cosmonauts aboard the Russian orbital station MIR, during the Franco-Russian mission ALTAIR, 1993. Movements of reflective markers were recorded using a videocamera, successive images being reconstructed by computer every 40ms. The position of the CM, ankle joint torques and shank and thigh angles were computed for each subject pre- in- and post-flight using a 7-link mathematical model. Results showed that both cosmonauts adopted a backward leaning posture prior to reaching movements. Inflight, the CM was displaced throughout values in the horizontal axis three times those of pre-flight measures. In addition, ankle dorsi flexor torques inflight increased to values double those of pre- and post-flight tests. This study concluded that CM displacements do not remain stable during complex postural equilibrium tasks executed in weightlessness. Furthermore, in the absence of gravity, subjects changed their strategy for producing ankle torque during spaceflight from a forward to a backward leaning posture.

Aerospace Medicine↗
PubMedDate not supplied

[Chronic cholesteatomatous otitis media: the histopathological and clinical aspects].

In recent years the immunologic aspects of the normal and pathological ear have been studied by several authors, with particular attention given to the histopathologic aspects of the epidermis of the tympanic membranes of the outer ear canal and of the middle ear mucosa in normal physiologic as well as in inflammatory conditions. Such studies may help in giving a more precise definition to the pathogenesis and clinical behavior of middle ear cholesteatoma. In this paper we report the results of an immunohistopathologic study carried out using the immunohistochemical technique of monoclonal antibodies on cholesteatoma matrix samples taken during radical mastoidectomy or tympanoplasty. In particular, the presence of T-lymphocytes and Langerhans cells was evaluated using selective monoclonal antibodies and a relationship between the data collected and the clinical expression of the disease in each case was sought. In this study it was not possible to establish a close relationship between clinical behavior and immunohistopathological findings, which appeared rather similar in all the cases. The presence of Langerhans' cells may confirm the hypothesized role they play in phlogistic reactions and bone reabsorption due to the presence of the cholesteatoma in the middle ear. Yet, in order to evaluate their true role correctly, more detailed studies should be carried out on the spatial distribution of T-lymphocytes and Langerhans' cells in the cholesteatoma matrix as well as on their ultrastructural characteristics.

Adult↗