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Biomedical subjects

M Maurizi

Publications and source records attributed to M Maurizi.

At least 91 records · Page 5Linked to original sources
PubMed1983

Effects of stimulus repetition rate on the auditory brain stem responses (ABR).

Brain stem auditory evoked potentials were recorded from 26 normal subjects who listened to 100 ms clicks at 10, 20, 50, and 100 repetitions per second at varying intensities. A 0.5+/-0.3 ms shift of the V wave latency was observed between 10 clicks per second and 100 clicks per second; a lesser difference was found when the repetition rate was shifted between 10 to 50, 20 to 50, or 20 to 100 clicks per second. No significant differences were observed when the repetition rate moved from 10 to 20 or between 50 and 100 clicks per second. Whatever latency shifts were observed appeared to be independent of the stimulus intensity. Waveform morphology seemed to be the same between 10 and 20 clicks per second, with only minor changes observed at the 50 clicks per second rate. At 100 clicks per second a decrease or a complete disappearance of some components or both was seen. These changes are accounted for by peripheral phenomena for the most part, and a number of clinical applications are suggested based on these observations.

Acoustic Stimulation↗
PubMed1982

Arteriovenous fistula of the mandible: a review of the literature and report of a case.

The authors, after a careful review of the literature during the last 15 years concerning arteriovenous malformation (AVM) of the jaws, report a case of congenital arteriovenous fistula of the mandible characterized by several episodes of spontaneous hemorrhage requiring emergency hemimandibulectomy. Radiologic, arteriographic and pathologic aspects of this lesion are discussed. Even though nomenclature concerning AVM of the jaws is confusing the authors draw attention to the embryologic features which are responsible for these lesions. They also point out the main diagnostic and therapeutic aspects emphasizing the small effect that ligation of the external carotid artery has on bleeding and the importance of choosing case by case the best treatment considering the great variety of clinical and pathologic aspects that characterize these lesions.

Arteriovenous Fistula↗
PubMed1982

Auditory brainstem responses (ABR) in the aged.

86 male subjects, aged between 60 and 86 years (M = 69.5), underwent pure-tone audiometry, impedance tests and brainstem response audiometry (BRA). Subjects have been classified into four age-related groups: 1) 34 subjects, aged between 60 and 65; 2) 22, aged between 66 and 70; 3) 22 aged between 71 and 75; 4) 8, aged between 76 and 86. They have also been classified into four groups on the basis of their mean auditory threshold at 0.5, 1, 2, 4 and 8 kHz: 1) 14 subjects with mean auditory threshold less than or equal to 30 dB HL; 2) 16, between 31 and 40; 3) 24, between 41 and 50; 4) 32, with mean auditory threshold greater than or equal to 51 dB HL. 19 normally hearing adults, aged between 28 and 42, were chosen as controls. Statistically significant correlations have been found between age and mean auditory threshold (P less than or equal to 0.001), between wave latency V and age (P less than or equal to 0.001), between wave latency V and the mean pure-tone auditory threshold at 0.5, 1, 2, 4 and 8 kHz (P less than or equal to 0.001) and between the V-I interval and age (P less than or equal to 0.001). The discrepancy between the mean auditory threshold and the ABR waveform, the overall amplitude's reduction of ABR waves and the progressive lengthening of V-I interval values, seem to indicate that age-related changes involve not only the end organ but also the brainstem auditory structures.

Age Factors↗
PubMed1981

Reference values and characteristics of brain stem audiometry in neonates and children.

ABR (Auditory Brainstem Response) delivering the acoustic stimulus both through a headphone (PHN) and in free field (FF), have been recorded in 59 "normal" children divided into four age-related groups: (1) 22 children born at a gestational age ranging between the 36th and the 41st week; (2) 12 with ages ranging from 1 to 6 months; (3) 15 with ages ranging from 6 to 12 months; (4) 10 with ages ranging from 12 to 36 months. Peak latency values obtained with FF technique have been corrected by calculating the delay due to the distance between the loudspeaker and the tested ears (2.04 ms). When using this correction, no statistically significant differences were found between latency values of peaks JI and JV recorded using the two technique. While JI latency values of various groups do not differ significantly, groups 2--and especially group 1--JV latency values are statistically different from those of the 3rd and 4th group. This observation was confirmed by JV--JI interval values. JV wave in neonates (group 1), using PHN technique, is detectable at 60 dB p.e. SPL (82%) while in all other groups at 60 dB this wave is clearly detectable in all children (100%). Using FF technique, JV wave is still visible at 60 dB in 78% of the neonates (group 1) and in almost all children of the other groups. Considering ABR waveform, using PHN technique, in the first two groups only three waves are visible and the first one disappears at about 80 dB, while the typical 4--5 waves of normal adult tracings are detectable since 8--12 months of age. FF tracings instead show three peaks in all groups, the first (JI) being less evident when compared with the one obtained using PHN technique. JV amplitude values observed in FF are higher than those obtained delivering the stimulus through the headphone.

Acoustic Stimulation↗
PubMed1980

Pulmonary function studies in adenoid hypertrophy.

Tests of pulmonary function were performed on children with severe adenoid hypertrophy, before and one month after adenoidectomy. Five types of subjects were selected: (1) normal; (2) cases with isolated increase of residual volume (RV); (3) supernormal type with increased RV; (4) obstructive type of ventilatory defect, and (5) restrictive type of ventilatory defect. Following adenoidectomy there is an objective evidence of improved pulmonary function. The data suggest that 65.7% of clinically normal children with adenoid hypertrophy show pulmonary function abnormalities.

Adenoidectomy↗
PubMedDate not supplied

Study on normal and otosclerotic bone cell cultures: an advance in understanding the pathogenesis of otosclerosis.

The authors first reviewed the main theories concerning the pathogenesis of otosclerosis and studied the morphologic and functional characteristics of cell cultures derived from normal and otosclerotic bones. Light transmission and scanning electron microscopy did not permit definite identification of the cultured cells as predominantly osteoblasts, nor did these techniques show significant differences between cultured cells derived from normal and pathologic bone. Functional tests of the cell cultures proved more interesting. First, the bony nature of the cultured cells was demonstrated by studying the intracellular 45Ca++ uptake after stimulation with calcitonin and dybutryl-cAMP. Second, cell cultures derived from otosclerotic bone behaved differently from those derived from normal bone. Their peak uptake of calcium appeared later, and post-stimulatory values were higher, suggesting that cells derived from otosclerotic bone store a greater quantity of 45Ca++. Furthermore, after stimulation with calcitonin and propranolol, we observed an inhibition of the calcium uptake and decreased intracellular cAMP levels in normal bone cell cultures. In contrast, the cell cultures derived from otosclerotic bone exhibited an initial inhibition of calcium absorption followed by massive calcium penetration. The response of adenylate cyclase to the action of Mg++, Ca++, and F- ions was evaluated in cultures derived from normal bone, otosclerotic bone, and normal skin fibroblasts. The resulting data show that activation due to Mg++ is much lower in cultured cells derived from otosclerotic bone than in those from either normal bone or skin fibroblasts. No significant differences were found after Ca++ inhibition in any of the cell cultures. Moreover, in cell cultures derived from normal bone, F- ions induced a strong activation that was lower than the levels observed in cultures of otosclerotic bone or in normal fibroblasts. We hypothesize that an alteration at the calcitonin receptor site is responsible for the difference in calcium uptake and cAMP levels observed in the cells derived from otosclerotic bone as compared to those cultured from normal cells.

Adenylyl Cyclases↗
PubMedDate not supplied

Clinical-morphological correlation of nasal obstruction with skull base development and otitis media. An experimental study.

Morphological changes of the middle ear were investigated by means of microotoscopy and scanning electron microscopy in 40 developing Albino rats. In 20 one nostril (group B) and in 20 both nostrils (group C) had been experimentally obstructed. 20 rats were used as controls (group A). Microotoscopy and scanning electron microscopy on the middle ear mucosa were performed when the animals were 2 months old, i.e. at 90% of their development. At microotoscopy the tympanic membranes, homolateral to the obstructed nostril, proved to be abnormal in 81% of group B rats and in almost all rats belonging to group C. Scanning electron microscopy, performed after the bullae had been removed, showed the following epithelial surface changes of the middle ear homolaterally to the obstructed nostril: (a) a significant increase of nonciliated elements with a secretory behavior as compared to controls, even of the floor where normally a large number of ciliated cells is present; (b) several ciliated cells were destroyed and their cilia were irregular and untidy; (c) thick mucous secretions covered the floor of the tympanic bulla; and (d) squamous metaplasia of the hypotympanic epithelium. Extrarotation of the eustachian tubes and developmental abnormalities of the skull base in growing rats, caused by nasal obstruction, seem to be able to induce pathological events of the middle ear.

Animals↗
PubMedDate not supplied

Morphological distribution of middle-ear epithelium in the Wistar rat: a functional hypothesis.

The authors studied the overall microscopical anatomy of the middle ear and of the eustachian tube in 20 tympanic bullae of 10 Wistar rats. Large hexagonal epithelial flat cells covered the roof of the bulla, the two upper thirds of both lateral walls, the upper half of the eustachian tube, and the upper third of the tympanic orifice; ciliated and secretory cells lined the inferior thirds of both walls of the bulla while a ciliated epithelium with strong cilia, all directed towards the tubal orifice, located on the floor of the tympanic cavity together with groups of non-ciliated cells was detectable near the tubal and antral areas and on the floor of the eustachian tube. Non-ciliated cells covered by microvilli were found near the pharyngeal orifice. These observations seem to demonstrate the following: (1) the ciliated elements present a well-defined topographic distribution; (2) a preferential pathway for mucociliary clearance made up of strong ciliated cells located on the floor of the bulla is clearly detectable, and (3) the roof of the bulla seems to be mainly involved in the ventilatory function.

Animals↗