Leonardo Nicola Siri

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Reduction in overall heart rate variability (HRV) associated with aging is determined by a decreased amplitude of heart rate oscillations at all frequency levels, including high frequency (HF) oscillations attributed to respiratory sinus arrhythmia, low frequency (LF) oscillations attributed to Meyer waves and very low frequency (VLF) oscillations of an(More)
The diurnal variations and photic regulation of cyclic AMP and melatonin content in golden hamster retina were studied. Both parameters showed significant diurnal variations with maximal values at night. Light exposure during the night inhibited retinal cyclic AMP and melatonin levels, whereas exposure to darkness during the day significantly increased(More)
Heart rate variability (HRV) is a complex signal that results from the contribution of different sources of oscillation related to the autonomic nervous system activity. Although linear analysis of HRV has been applied to sleep studies, the nonlinear dynamics of HRV underlying frequency components during sleep is less known. We conducted a study to evaluate(More)
1. Current and voltage clamp experiments were carried out on frog skeletal muscle fibres. For voltage clamp, the three micro-electrode technique near the fibre end was used. 2. Calcium spikes and currents were recorded in TEA sulphate saline. The addition of 400 mM-glycerol did not appreciably modify them. 3. Muscle fibers were detubulated with the glycerol(More)
Patients with anorexia nervosa or bulimia nervosa often have signs of autonomic dysfunction potentially deleterious to the heart. The aim of this study was to ascertain the nonlinear properties of heart rate variability in patients with eating disorders. A group of 33 women with eating disorders (14 anorexia, 19 bulimia) and 19 healthy controls were(More)
Slow Ca-action potentials (CaAP) were studied in normal human skeletal muscle fibers obtained during surgery (fibers with both ends cut). Control studies also were carried out with intact as well as cut rat skeletal muscle fibers. Experiments were performed in hypertonic Cl-free saline with 10 or 84 mM Ca and K-channel blockers; muscles were preincubated in(More)
Electrodermal responses in the facial region of freely moving rats were recorded bilaterally. After a nociceptive stimulus (ammonia vapor exposure), the response (a transient negative potential followed by a longer-lasting positive potential) attained a similar amplitude on both sides. Surgical sympathetic denervation of facial skin by ipsilateral superior(More)
The effect of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on the release process was studied in presence of different extracellular Ca2+ concentrations, in the mouse phrenic-diaphragm preparation. Hemidiaphragms were incubated for 2 h at room temperature in the presence or absence of TPA. TPA increased the basal frequency of miniature end(More)
Two types of fibres were characterized in the cruralis muscle of the toad using electrophysiological techniques: the slow and the fast fibres. Five to ten slow fibres were easily identified on the inner face of this muscle. The cruralis slow fibres developed the ability to produce action potentials 40 days after the sciatic nerve was transected at the hip(More)
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