Biomedical subjects

Aldo Ferraresi

Publications and source records attributed to Aldo Ferraresi.

8 recordsLinked to original sources

PubMed2006

Motor performance changes induced by muscle vibration.

The possibility that mechanical stimulation of selected muscles can act directly on the nervous system inducing persistent changes of motor performances was explored. On the basis of literature, stimulating parameters were chosen to stimulate the central nervous system and to avoid muscle fibre injuries. A sinusoidal mechanical vibration was applied, for three consecutive days, on the quadriceps muscle in seven subjects that performed a muscular contraction (VC). The same stimulation paradigm was applied on seven subjects in relaxed muscle condition (VR) and seven subjects were not treated at all (NV). Two sessions (PRE and POST) of isometric and isotonic tests were performed separated for 21 days, in all studied groups 7 days before and 15 days after stimulation, whilst an isokinetic test was performed on VC only. In the isometric test, the time of force development showed a significant decrease only in VC (POST vs PRE mean 27.8%, P < 0.05). In the isotonic test, the subjects' had to perform a fatiguing leg extension against a load. In this condition, the fatigue resistance increased greatly in VC (mean 40.3%, P < 0.001), increased slightly in VR and there was no difference in NV. In Isokinetic test, at several angular velocities, significantly less time was required to reach the force peak (mean 20.2% P < 0.05). The findings could be ascribed to plastic changes in proprioceptive processing, leading to an improvement in knee joint control. Such action delineates a new tool in sports training and in motor rehabilitation.

Adaptation, Physiological↗

PubMed2006

Protective properties of idebenone in noise-induced hearing loss in the guinea pig.

Idebenone is a synthetic analogue of coenzyme Q10 with antioxidant properties. The present study investigated the antioxidant activity of idebenone in the rescue of acoustic trauma. Noise-induced hearing loss was induced by exposing guinea pigs to a continuous pure tone and idebenone was injected intraperitoneally 1 h before noise exposure and once daily for 3 days. Guinea pigs treated with idebenone showed significantly smaller auditory threshold shifts than unprotected control animals. Missing and apoptotic cells were identified with scanning electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Protected animals presented a lesser extent of both apoptotic activation and hair cell loss in the organ of Corti. Our results suggest an antioxidant function of idebenone in protection from noise-induced hearing loss and provide a rationale for exploring therapeutic strategies in humans.

Acoustic Stimulation↗

PubMed2005

Head-body righting reflex from the supine position and preparatory eye movements.

CONCLUSION: Saccular and utricular maculae can provide information on the supine static position, considering that both have pronounced curved structures with hair cells having a variety of polarization vectors that enable them to sense an inverted position and thus direct the righting reflex. OBJECTIVE: The vestibular system is essential for the structuring of motor behaviour, senses linear and angular acceleration and has a strong influence on posture and balance at rest, during locomotion and in head body righting reflexes. MATERIAL AND METHODS: Using guinea pigs in the supine position with a symmetrical head and trunk position, the ocular position was analysed to ascertain whether any ocular movement that occurred would adopt a spatial deviation indicative of the subsequent head and body righting. The characteristics of the righting reflex (direction, latency, duration and velocity) were analysed in guinea pigs from position signals obtained from search coils implanted in the eye, head and pelvis. The animals were kept in a supine position for a few seconds or even minutes with the eyes in a stable primary position and the head and body symmetrical and immobile. RESULTS: The righting reflex took place either immediately or after a slow deviation of the eyes. In both cases the righting sequence (eyes, head, body) was stereotyped and consistent. The direction of head and body righting was along the longitudinal axis of the animal and was either clockwise or anticlockwise and the direction of righting was related to the direction of the eye deviation. The ocular deviation and the direction of deviation that initiated and determined the direction of the righting reflex could be explained by possible otolithic activation.

Animals↗

PubMed2004

Low-frequency loud acoustic stimulation and goal-directed arm movements.

OBJECTIVE: To analyse the effects of low-frequency loud acoustic stimulation on goal-directed movements involving the arm. Low-frequency sound stimulation impairs eye stability, evokes a subjective tilt of the visual surround in subjects presenting Tullio's phenomenon and induces, in normal subjects, short-latency evoked potentials in the neck and limb muscles. MATERIAL AND METHODS: Healthy subjects performed goal-directed movements in the horizontal plane with the right (dominant) arm to a fixed 3 degree-wide target positioned at an angle of 30 degrees, with the instruction to perform fast and accurate movements to the target and to hold the final position. This fast-pointing task was performed in association with sound-induced vestibular-otolithic stimulation (110 dB SPL, 500 Hz) in the absence of visual guidance (i.e. pointing at a memorized target in the absence of target or pointer cues). Pointing errors were analysed by computing the constant errors made by the subjects (mean error). Pointing errors were also correlated with movement kinematics (movement duration, peak velocity, time to peak velocity) and with the reaction time of movement. RESULTS: The low-frequency loud acoustic stimulation modified the final position of the arm-pointing task at the memorized target in the absence of vision. CONCLUSION: Goal-directed movements are achieved by means of sensory interactions between visual, somatosensory and vestibular information and the vestibular-otolithic signals contribute to the accuracy of voluntary arm movements.

Acoustic Stimulation↗

PubMed2004

alpha-Tocopherol protective effects on gentamicin ototoxicity: an experimental study.

Gentamicin, acting as an iron chelator, activates membrane lipid peroxidation (MPL) and induces free radical formation, as observed in vitro and in vivo. Antioxidants, such as alpha-tocopherol, are able to suppress MLP, thus attenuating tissue damage. The present study was designed to investigate the possible protective effects of alpha-tocopherol on gentamicin ototoxicity. The study was carried out on albino guinea pigs (250-350 g). The animals were divided into four groups: group A (n = 4), injected with corn oil daily at a dose of 100 mg/kg body weight intramuscularly (IM); group B (n = 10), treated with corn oil at a dose of 100 mg/kg body weight and gentamicin base at a dose of 100 mg/kg body weight (IM); group C (n = 10). treated with gentamicin alone at a dose of 100 mg/kg body weight (IM); and group D (n = 10), treated with gentamicin at the same dose plus alpha-tocopherol acetate at dose of 100 mg/kg body weight (IM). Electrocochleographic recordings were made from an implanted round-window electrode. All animals were treated for 14 days. The compound action potentials (CAPs) were measured at 2-16 kHz at days 0, 10, 14 and 18 after treatment. Changes in cochlear function were characterized as CAP threshold shifts. Morphological changes were analysed by scanning electron microscopy. Gentamicin induced progressive high-frequency hearing loss of 50-60 dB SPL. alpha-Tocopherol co-therapy slowed the progression of hearing loss. The significant loss of outer hair cells (OHCs) in the cochlear basal turn in gentamicin-treated animals was not observed in the cochleas of animals protected with alpha-tocopherol. This study supports the hypothesis that alpha-tocopherol interferes with gentamicin-induced free radical formation, and suggests that this drug may be useful in protecting OHC function from aminoglycoside ototoxicity, thus reducing hearing loss.

Action Potentials↗

PubMed2003

Cisplatin ototoxicity in the guinea pig: vestibular and cochlear damage.

The aim of the present study was to investigate both vestibular and cochlear cisplatin toxicity. Twelve albino guinea pigs were divided into an experimental (n=8) and a control saline group (n=4) and were treated with cisplatin at a daily dose of 2.5 mg/kg for 6 consecutive days. Vestibular dysfunction was evaluated by computing the gain of the vestibular ocular reflex (VOR) evoked by stimulation in the horizontal (HVOR) and vertical (VVOR) planes. Changes in cochlear function were characterised as compound action potential threshold shifts. After the functional testing, tympanic bullae were removed and processed for morphological examination of the sensorineural epithelium. The onset of vestibular functional impairment was observed on the third day, although the VOR gain decrease was not significant. The impairment of the vestibular function progressed until the sixth day becoming statistically significant particularly at VVOR mid frequencies of stimulation. At these frequencies both macula and crista ampullaris functions are involved. Concomitantly a progressive auditory threshold shift was observed at all stimulus frequencies. The decline of the auditory function was statistically significant from the third day of treatment and it was more evident at high frequencies. Morphological observations showed a massive loss of outer hair cells and a degeneration of the organ of Corti in the basal/middle turns and only a slight loss of hair cells of the cristae ampullares and maculae. In conclusion, functional and morphological data provide evidence that the toxic effect of cisplatin is more pronounced in the organ of Corti than in the vestibular epithelium.

Action Potentials↗

PubMed2003

Eye instability in the rabbit induced by vestibular stimulation in the vertical plane.

OBJECTIVE: Sinusoidal vestibular stimulation in the horizontal plane induces periodic eye instability in the intact rabbit and the hypothesis of an intrinsically unstable velocity storage mechanism has been conceived. The present research examined the stability of the vestibulo-ocular reflex (VOR) in the vertical plane, considering that the time constant values of vertical and horizontal VORs differ and that separate regions of the vestibulo-cerebellum affect the horizontal and vertical slow VOR components differently. MATERIAL AND METHODS: Normal pigmented rabbits were sinusoidally oscillated in the dark about their vertical and longitudinal axes to evoke horizontal and vertical eye responses. RESULTS: Frequency and peak-to-peak amplitude stimulation parameters ranged from 0.1 to 0.8 Hz and from 5 degrees to 20 degrees, respectively. During horizontal VOR, periodic alternating drift (PAD) was superimposed on the ocular response, and both peak velocity and period were directly correlated with stimulation amplitude. Vestibular stimulation in the vertical plane induced PAD: the period of vertical PAD was shorter and the amplitude smaller than the corresponding horizontal PAD values. A further difference in vertical PAD occurred in the lack of modulation of period and peak velocity by the stimulus amplitude. CONCLUSION: These results support the hypothesis of different instabilities of the velocity storage mechanism in the vertical and horizontal planes, possibly due to separate sensory-motor systems sub-serving the vertical and horizontal VORs.

Adaptation, Ocular↗

PubMed2003

Protective effects of alpha-tocopherol against gentamicin-induced Oto-vestibulo toxicity: an experimental study.

OBJECTIVE: Free radicals are involved in gentamicin ototoxicity and vestibular dysfunction and it has been demonstrated that free radical scavengers, such as alpha-tocopherol, are able to inactive free radicals, attenuating tissue damage This study was designed to investigate the possible protective effects of alpha-tocopherol against gentamicin-induced oto-vestibulo toxicity. MATERIAL AND METHODS: Adult albino guinea pigs were divided into four groups and were treated for 2 weeks as follows: Group A, controls; Group B, gentamicin plus corn oil; Group C, gentamicin only; and Group D, gentamicin plus alpha-tocopherol. To evaluate vestibular function, the animals underwent sinusoidal oscillations in the dark about their vertical and longitudinal axes to evoke horizontal and vertical vestibulo-ocular reflexes (VORs), respectively. Electrocochleographic recordings were performed using an implanted round window electrode. The compound action potentials (CAPs) at 2, 4, 8 and 16 kHz were measured every 5 days Morphological changes were analysed by means of scanning electron microscopy. RESULTS: Gentamicin induced a consistent reduction in VOR responses and a progressive high-frequency hearing loss of 50-60 dB sound pressure level. Alpha-Tocopherol co-therapy slowed the progression of hearing loss and significantly attenuated the final threshold shifts The impairment of vestibular function was reduced, as evidenced by an increased VOR gain. The massive loss of outer hair cells in the cochlear basal turn and of cristae ampullaris stereocilia in gentamicin-treated animals was not observed in the cochlea of animals protected with alpha-tocopherol. CONCLUSION: This study supports the hypothesis that alpha-tocopherol interferes with gentamicin-induced free radical formation, and suggests that this drug may be useful in preventing aminoglycoside oto-vestibulo toxicity.

Animals↗