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Biomedical subjects

J W Hall

Publications and source records attributed to J W Hall.

17 recordsLinked to original sources
PubMed1992

Cryobiological preservation of Drosophila embryos.

The inability to cryobiologically preserve the fruit fly Drosophila melanogaster has required that fly stocks be maintained by frequent transfer of adults. This method is costly in terms of time and can lead to loss of stocks. Traditional slow freezing methods do not succeed because the embryos are highly sensitive to chilling. With the procedures described here, 68 percent of precisely staged 15-hour Oregon R (wild-type) embryos hatch after vitrification at -205 degrees C, and 40 percent of the resulting larvae develop into normal adult flies. These embryos are among the most complex organisms successfully preserved by cryobiology.

Animals↗
PubMed1992

Masking release for gap detection.

In random noise, masking is influenced almost entirely by noise components in a narrow band around the signal frequency. However, when the noise is not random, but has a modulation pattern which is coherent across frequency, noise components relatively remote from the signal frequency can actually produce a release from masking. This masking release has been called comodulation masking release (CMR). The present research investigated whether a similar release from masking occurs in the analysis of a suprathreshold signal. Specifically, the ability to detect the presence of a temporal gap was investigated in conditions which do and do not result in CMR for detection threshold. Similar conditions were investigated for the masking level difference (a binaural masking release phenomenon). The results indicated that suprathreshold masking release for gap detection occurred for both the masking-level difference (MLD) and for CMR. However, masking release for gap detection was generally smaller than that obtained for detection threshold. The largest gap detection masking release effects obtained corresponded to relatively low levels of stimulation, where gap detection was relatively poor.

Acoustic Stimulation↗
PubMed1992

Comparison of Etymotic insert and TDH supra-aural earphones in auditory brainstem response measurement.

There are few systematic comparisons of Etymotic ER-3A insert earphones versus supra-aural earphones in auditory brainstem response (ABR) measurement. We compared ER-3A insert earphones and two types of supra-aural earphones (TDH-39P and TDH-49P) in a group of normal hearing adults. Acoustic analyses revealed spectral and temporal differences among earphones. Behavioral and ABR thresholds to click stimuli were slightly elevated with the ER-3A compared to the TDH earphones. The ER-3A earphones produced a latency delay, relative to the TDH earphones, that varied from about 0.8 to 1.0 msec, and increased at lower stimulus intensity levels. In addition, ABR wave I amplitude was significantly reduced with the ER-3A earphone. Based on these data, we recommend collection of normative data with the ER-3A earphones prior to their use in ABR measurement.

Acoustic Stimulation↗
PubMed1979

Effects of age and sex on static compliance.

The effects of age and sex on static compliance values were analyzed in 336 patients. Static compliance of the normal middle ear varies as a function of age and sex. In men and women, static compliance values are maximum between 31 and 40 years of age, and then decrease relatively systematically with increasing age. Under 30 years of age, static compliance values are slightly greater in female subjects. From 30 to 60 years of age, men show substantially greater static compliance measurements. Above 60 years of age, static compliance is comparable for both sexes. Comparison of normal vs otosclerotic ears showed that the age effect considerably reduces the clinical usefulness of the static compliance measure. The overall findings of this study support the concept of decreased compliance of the middle ear system with increasing age.

Acoustic Impedance Tests↗
PubMed1979

Impedance audiometry in a young population. The effect of age, sex, and tympanogram abnormalities.

Static compliance, and acoustic reflex thresholds, were studied retrospectively in 883 subjects, aged one to 20 years. Age was a factor in both measurements. In 523 subjects with normal middle ear fuction, static compliance increased as a function of age. Acoustic reflex thresholds for pure tone signals improved with age, while acoustic reflex thresholds for broad band noise (BBN) tended to decrease. Minor tympanogram abnormalities exerted a distinct influence on static compliance and acoustic reflex thresholds. Static compliance was increased, and highly variable, in 93 subjects with A-deep tympanograms. In 212 subjects with either A-deep tympanograms, or slight negative pressure (i.e. -50 to -100 mm H2O), acoustic reflex thresholds were elevated for both pure tone, and BBN signals. In 132 sensorineural impaired subjects, the sensitivity loss differentially affected acoustic reflex thresholds for pure tone vs BBN signals. In view of the potential influence of age, and, especially, minor middle ear abnormalities, on static compliance and acoustic reflex measures, these factors should be seriously considered when interpreting impedance audiometry findings in children.

Acoustic Impedance Tests↗
PubMed1978

Predicting hearing level from the acoustic reflex. A comparison of three methods.

Three prediction methods based on the acoustic reflex noise-tone difference (NTD) were used to predict hearing level in 370 subjects. The methods were two versions of the sensitivity prediction by acoustic reflex (SPAR) and a formula for estimating hearing threshold level. With each method, hearing loss was correctly predicted in more than one half of the subjects, while serious predictive error occurred in less than 10%. Age was found to be an important factor in hearing level prediction. Predictive accuracy for each method decreased systematically as a function of age. Predictive accuracy for the two SPAR methods decreased dramatically in subjects with minor middle ear and/or tympanogram abnormalities. Nevertheless, the value of the acoustic reflex NTD in predicting hearing level was confirmed.

Acoustic Impedance Tests↗
PubMed1978

Central auditory function in stutterers.

Central auditory function was assessed in 10 stutterers and 10 nonstutterers. Performance of the two groups was compared for seven audiometric procedures including acoustic reflex threshold, acoustic reflex amplitude function, performance intensity function for monosyllabic phonetically balanced (PB) words, performance intensity function for Synthetic Sentence Identification, Synthetic Sentence Identification with Ipsilateral Competing Message, Synthetic Sentence Identification with Contralateral Competing Message, and the Staggered Spondaic Word test. Relative to the control group, the performance of the stuttering group was depressed on three procedures--the acoustic reflex amplitude function, Synthetic Identification with Ipsilateral Competing Message, and Staggered Spondaic Word test. As a group, the stutterers presented evidence of a central auditory deficiency. The pattern of test results suggests a disorder at the brainstem level. The subtlety of the deficiency is emphasized.

Acoustic Impedance Tests↗
PubMed1978

Adaptation of residue pitch.

Residue pitch was examined by means of adaptation. The monaural perceptibility of a residue pitch was measured before and after exposure to ipsilateral or contralateral adapatation stimuli of variable spectral composition. Several aspects of adaptation were investigated: pitch channel specificity, number of stimulus components necessary to adapt a residue channel, importance of temporal and spectral factors for adaptation, and the relation between pure-tone and residue pitch. It was found that there are residue-pitch channels specifically sensitive to the spectral region and ear of presentation of the stimulus. At least two harmonics were necessary to adapt a residue channel, and pitch channels were found to be insensitive to temporal factors. Residue and pure-tone pitch seemed to be extracted by different mechanisms, having independent channels. The data presented augment the understanding of pitch perception and suggest refinements for pitch-perception models.

Cues↗
PubMed1977

Cinoxacin: new antimicrobial agent for urinary tract infections.

One hundred forty-six patients with recurrent urinary tract infections were treated with 500 mg. of cinoxacin twice daily for seven to fourteen days. Satisfactory clinical response occurred in 94 per cent. Of the 100 patients with significant pretherapy bacteriuria (greater than or equal to 10(4) organisms/ml. of urine), 65 had complicated infections. Approximately the same per cent of patients with (90 per cent) as without (94 per cent) complicating conditions had a satisfactory clinical response to treatment. The pathogen was eliminated in a higher percentage of patients without underlying disease (90 versus 80 per cent), and infections recurred less frequently in this group (3 versus 14 per cent). Emergence of resistance by initially susceptible organisms during the course of therapy occurred in 4 of 76 patients (5 per cent). A satisfactory clinical response occurred in all 46 patients with an initial colony count of less than 10(4) organisms/ml. urine. Only 1 patient in this group was a bacteriologic failure. Adverse effects of a relatively wild nature were seen in 4 of 146 patients (2.7 per cent). Successful eradication of 12 of 23 urinary infections in patients whose pathogens were resistant to the 30-microgram. cinoxacin disk suggests that the 100-microgram. disk may be more realistic for determining bacterial susceptibility by the disk diffusion method in view of the very high urinary concentration of the drug.

Adult↗
PubMed1977

Elements of timbre perception.

An evaluative review of the timbre perception literature is made. Attention is given to physical, psychological, and physiological factors involved in the perception of controlled musical and speech stimuli. Timbre perception is considered to be a complex process involving the synthesis of three main elements: the overtone structure of the stimulus, a temporal integration of acoustical events, and the context of the stimulation.

Acoustic Stimulation↗
PubMed1976

Acoustic reflex characteristics in spastic dysphonia.

Acoustic reflex characteristics were studied in six persons with spastic dysphonia. Two methods of analysis were used: (1) a double-blind qualitative judgment of acoustic reflex recordings, and (2) a quantitative analysis of specific temporal characteristics of the acoustic reflexes. Judgments of reflex recordings did not reliably differentiate spastic dysphonia subjects from controls. An analysis of five latency measures revealed a difference between groups only in one measure, reflex contraction time.

Acoustic Stimulation↗
PubMed1975

The joint toxic action of perchloroethylene with benzene or toluene in rats.

The joint toxic action of mixtures of perchloroethylene with benzene or toluene was tested at five dose levels for each of six binary combinations with 20 rats per dose. LD50 data with 95% fiducial limits are reported for each mixture and tests for additive joint toxicity were made. The results indicate that the mixtures of perchloroethylene and benzene gave values for the LD50 which were slightly less than additive while perchloroethylene and toluene mixtures had LD50 values which could not be predicted by an additive model.

Animals↗
PubMed1975

A procedure for the detection of pollution by fish movements.

An "alarm" system using fish movements has recently been developed to provide rapid information about accidental spills of pollutants. The data are the realization of a non-stationary stochastic process which takes on discrete values. By the use of the Camp-Paulson approximation, the process is transformed to a strictly stationary one for which calculations are tractable. A procedure is then presented to detect the presence of pollutants. Tests with real data indicate that it detects them sooner than the method used previously.

Animals↗