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Biomedical subjects

C A Silverman

Publications and source records attributed to C A Silverman.

24 records · Page 2Linked to original sources
PubMed1984

Late-onset auditory deprivation: effects of monaural versus binaural hearing aids.

Performance on tests of pure-tone thresholds, speech-recognition thresholds, and speech-recognition scores for the two ears of each subject were evaluated in two groups of adults with bilateral hearing losses. One group was composed of individuals fitted with binaural hearing aids, and the other group included persons with monaural hearing aids. Performance prior to the use of hearing aids was compared to performance after 4-5 years of hearing aid use in order to determine whether the unaided ear would show effects of auditory deprivation. There were no differences over time for pure-tone thresholds or speech-recognition thresholds for both ears of both groups. Nevertheless, the results revealed that the speech-recognition difference scores of the binaurally fitted subjects remained stable over time whereas they increased for the monaurally fitted subjects. The findings reveal an auditory deprivation effect for the unfitted ears of the subjects with monaural hearing aids.

Audiometry, Pure-Tone↗
PubMed1983

The acoustic reflex threshold in aging ears.

This study investigates the controversy regarding the influence of age on the acoustic reflex threshold for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators between Jerger et al. [Mono. Contemp. Audiol. 1 (1978)] and Jerger [J. Acoust. Soc. Am. 66 (1979)] on the one hand and Silman [J. Acoust. Soc. Am. 66 (1979)] and others on the other. The acoustic reflex thresholds for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators were evaluated under two measurement conditions. Seventy-two normal-hearing ears were drawn from 72 subjects ranging in age from 20-69 years. The results revealed that age was correlated with the acoustic reflex threshold for BBN activator but not for any of the tonal activators; the correlation was stronger under the 1-dB than under the 5-dB measurement condition. Also, the mean acoustic reflex thresholds for broadband noise activator were essentially similar to those reported by Jerger et al. (1978) but differed from those obtained in this study under the 1-dB measurement condition.

Acoustic Stimulation↗
PubMed1974

Butirosin compared with gentamicin in vitro and in vivo.

Butirosin (BTN) (P. W. K. Woo, G. L. Coffey, H. W. Dion, S. A. Fusari, and G. D. Senos, U. S. Patent 3,541,078, 1970) is a new aminoglycoside antibiotic notably active against opportunist bacterial species within Pseudomonas, Klebsiella, Enterobacter, Serratia, and Proteus. Numerous comparative tests were carried out with BTN and gentamicin (GTM) in vitro and in experimental infections in mice. BTN was more active in Mueller-Hinton broth than in agar, but its activity was lessened at acid pH or under anaerobiosis, as has been observed with other aminoglycosides. In standard agar diffusion tests, inhibition zones greater than 12 mm around 30-mug BTN disks generally denoted susceptibility, equivalent to minimal inhibitory concentrations [Formula: see text] 25 mug/ml. Cross-resistance between BTN and GTM occurred in a variable manner, with a number of bacterial strains strongly resistant to GTM being moderately susceptible to BTN. In mice, after a single subcutaneous injection, absorption of both antibiotics was rapid, with peak serum levels occurring in 15 min; this was followed by rapid elimination with estimated serum half-lives of about 20 min for each. After peroral administration of high doses in mice, there was no appreciable absorption of BTN. Several tests were carried out to compare BTN and GTM with respect to minimal inhibitory concentrations in vitro, acute subcutaneous median mouse protective doses, peak serum levels at such doses, and the therapeutic ratios derived from acute median protective and lethal doses. Although GTM usually proved to be more potent antibacterially on a weight basis, observations on BTN indicated a superior effectiveness in terms of therapeutic ratios.

Animals↗
PubMedDate not supplied

Temporal summation in acoustic reflex growth functions.

Acoustic reflex growth functions for pure tone activators of 500, 1000 and 2000 Hz and a broad-band noise (BBN) were obtained with activator durations of 20, 200 and 1000 msec (10 msec rise/decay) in four young, normal subjects. The lowest reflex thresholds were obtained for the 1000 msec activators, followed by 200 msec and then 20 msec. The reflex growth functions revealed lower reflex magnitudes for the shorter duration activators. When normalized to account for temporal summation at reflex threshold, reflex magnitude growth was similar among the three durations at 500 Hz, slower for 20 msec than for 200 and 1000 msec at 1000 Hz, and became progressively slower with decreasing duration from 1000 to 200 to 20 msec at 2000 Hz. When expressed in SPL, the BBN growth functions reasonably resembled those at 2000 Hz. No particular pattern was revealed for the normalized BBN growth functions.

Adult↗