Biomedical subjects

N Quaranta

Publications and source records attributed to N Quaranta.

26 records · Page 2Linked to original sources

PubMed1999

The value of CT scans in improving laryngoscopy in patients with laryngeal cancer.

This retrospective study assessed the value of computed tomography (CT) scan with contrast in improving the staging accuracy of indirect and direct laryngoscopy. We compared the preoperative staging obtained by the two latter procedures with postoperative histopathological findings in 187 patients operated on for laryngeal cancer. Of these cancers, 98 were supraglottic, 82 glottic and 7 subglottic in origin. The staging accuracy of laryngoscopy was 51.3% and CT was 70.1%. When the two procedures were combined, the staging accuracy was 80.2%. The accuracy of the CT increased from glottic to supraglottic to subglottic tumors, although the accuracy of laryngoscopy decreased in the same direction. Laryngoscopy alone tended to understage larger tumors (pT3 and pT4), whereas CT underestimated the smaller ones (pT1 and pT2). Our data suggest that in order to plan the best treatment both laryngoscopy and CT should be used in making the diagnosis.

Adult↗

PubMed1998

Effects of noise on inferior colliculus evoked potentials and cochlear anatomy in young and aged chinchillas.

Like many aging humans, the aging chinchilla tends to lose high-frequency sensitivity at a faster rate than low-frequency sensitivity. This feature, combined with its excellent low-frequency hearing, makes the chinchilla attractive as an animal model for studying the relationship between noise-induced hearing loss (NIHL) and age-related hearing loss (AHL). In the present study, we examined susceptibility to noise in 15 aged (10-15 years old) and 15 young chinchillas. Two levels of noise were used, with the aim of determining whether age-related differences exist in the magnitude and rate of recovery from temporary threshold shifts produced by a moderate-level (95 dB) noise exposure, or in susceptibility to permanent threshold shifts and cochlear damage caused by a high-level (106 dB) noise exposure. Thresholds and response amplitudes at 0.5, 1, 2, 4, 8 and 16 kHz were determined from evoked potentials recorded from the inferior colliculus. Cochlear histology was performed on animals exposed to high-level noise. The results suggest that older animals are equally vulnerable to moderate-level noise, but may be slightly more vulnerable to high-level noise. For moderate-level exposures, there appears to be a simple additive relationship (in dB) between AHL and NIHL. For high-level exposures, the relationship may be more complex.

Acoustic Stimulation↗

PubMed1998

Development of resistance to noise.

Recent investigations have demonstrated that in animal models repeated exposures to mid-intensity noise induce a progressive reduction of the temporary threshold shift (TTS) following the exposures. This phenomenon is named "conditioning" and it is actually able to reduce the permanent threshold shift (PTS) following exposure to high intensity noise; this finding is named "toughening". In the present work the fundamental steps of the research concerning the toughening are reviewed and the biological mechanisms supposed to be underlying this phenomenon discussed. The few preliminary results of the studies on humans are also reported.

Animals↗

PubMed1998

Auditory dysfunction in occupational noise exposed workers.

Occupational noise-induced hearing loss (NIHL) is well known to be an epidemiologically relevant problem. The subjects affected with NIHL show alteration of hearing thresholds as well as a worsening of the cochlear analysis functions and, usually, an impaired speech discrimination in presence of background noise. The study has evaluated the relationships between hearing threshold and equivalent exposure lever per day (Lepd), age and working seniority in a homogeneous sample of occupationally noise exposed workers. Three subgroups were also selected to study the most important cochlear functions as well as nerve and central functions. The first subgroup (Nn) contained normal hearing workers exposed to non-hazardous noise, while the second (Bn) contained workers exposed to high level continuous noise during their work day without clinical evidence of NIHL. The third subgroup (Bd) included subjects affected with the typical 4 kHz notch exposed to the same noise conditions than subgroup Bn. The results show that the hearing impaired subjects have the worst overall cochlear performance; however also the normal hearing workers exposed to hazardous noise have worse performance than subgroup Nn, relatively to high frequency thresholds, frequency resolution, TEOAEs, DPOAEs, stapedial acoustic reflex dynamic parameters. The results suggest that these measures could be used in the monitoring of the NIHL as indicators of subtle alterations of the hearing function.

Acoustic Impedance Tests↗

PubMed1997

Age-related decline of auditory function in the chinchilla (Chinchilla laniger).

The aim of this study was to examine the functional consequences of aging in the chinchilla, a rodent with a relatively long life span and a range of hearing similar to that of humans. Subjects were 21 chinchillas aged 10-15 years, and 23 young controls. Thresholds were determined from auditory evoked potentials (EVPs), and outer hair cell (OHC) functioning was assessed by measuring 2f1-f2 distortion product otoacoustic emissions (DPOAEs). Six cochleas from 11-12-year-old animals were examined for hair cell loss and gross strial pathology. The results show that the chinchilla exhibits a small but significant decline of auditory sensitivity and OHC functioning between 3 and 15 years of age, with high-frequency losses exceeding and growing more rapidly than low-frequency losses. Compared to rodents with shorter life spans, the chinchilla has a rate of loss that is more similar to that of humans, which could make it a valuable model for understanding the etiology of human presbycusis.

Acoustic Stimulation↗

PubMed1997

Suprathreshold measures of auditory function in the aging chinchilla.

The purpose of this study was to examine the relationship between aging and suprathreshold auditory function in the chinchilla, a rodent with a relatively long life span and a range of hearing similar to that of humans. Subjects were six 11-12-year-old chinchillas and six young controls. Tests of auditory function utilized evoked potential (EVP) recordings from electrodes implanted in the inferior colliculus and measurements of 2f1-f2 distortion product otoacoustic emissions (DPOAEs). Tests of frequency resolution (EVP tuning curves for a 2 kHz probe tone), temporal resolution (EVP forward masking functions using a 2 kHz probe tone), cochlear non-linearity (remote masking), and a DPOAE 'tone challenge', in which DPOAEs at six frequencies were monitored before and after each of five 1-min exposures to a 2 kHz tone at 80 dB SPL, were performed. The results indicate that aged chinchillas can exhibit deficits in suprathreshold tests of auditory function even when the test stimulus is in a region of relatively normal-hearing sensitivity. The results support the notion that aging, independent of hearing loss, can influence suprathreshold auditory function.

Aging↗

PubMedDate not supplied

Effect of ageing on otoacoustic emissions and efferent suppression in humans.

Transiently evoked otoacoustic emissions (TEOAEs) without and with contralateral acoustical stimulation, were recorded on 52 subjects ranging from 20 to 78 years. Subject selection was based on the hearing levels from 0.5 to 4 kHz being better than 25 dB HL, normal tympanograms and stapedial reflexes, presence of TEOAEs in at least one ear and no history of otological disease, noise exposure, ototoxic drugs, metabolic disease associated with hearing loss or a family history of hearing loss. The ear with better audiological thresholds was selected as the test ear. If there was no difference between the ears, the ear with stronger TEOAEs was selected. Subjects were divided into five age groups: 20-34 years (n=12, mean age 23.7), 35-44 (n=11, mean age 39.7), 45-54 (n=8, mean age 48.1), 55-64 (n=10, mean age 60), 65-78 (n=11, mean age 71). TEOAEs were never absent in the first two groups, but they were absent in two ears in the 45-54 group, and in one ear of the 55-64 and 65-78 groups. Mean TEOAE amplitude decreased with age, but the differences between the five groups were not significant. Contralateral white noise suppressed emission amplitude, but the amount of suppression was not significantly different between the five groups. A linear regression analysis showed a significant correlation between age and hearing levels, and a negative correlation between age and TEOAE amplitude. In addition, a significant negative correlation between hearing threshold and TEOAE amplitude was evident. No effect of age on the amplitude of the efferent suppression was found.

Adult↗

PubMedDate not supplied

Age-related histopathological changes of the stria vascularis: an experimental model.

The stria vascularis (SV) of 3-, 8- and 18-month-old C57 mice was examined with a fluorescence microscope in order to evaluate the capillary density and vessel diameter. The capillary density was significantly reduced in 18-month-old mice compared to 3-month-old (P<0.001) and to 8-month-old (P<0.001) mice. The difference between 3- and 18-month-old mice was significant for the basal, middle and apical cochlear turns, while the difference between 8- and 18-month-old mice was significant only for the middle and basal turns. Vessel diameter within the whole SV was significantly reduced in all turns in 18-month-old mice (P<0.01) versus 3-month-old animals, while vessel diameter was reduced only in the basal turn in 8-month-old versus 3-month-old mice. The results suggest that previously described histopathological changes in the organ of Corti of C57 mice may be related to modifications of strial capillaries.

Age Factors↗