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Biomedical subjects

D Hayes

Publications and source records attributed to D Hayes.

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

Signal-averaging of the acoustic reflex: diagnostic applications of amplitude characteristics.

We employed simultaneous measurement of the crossed and uncrossed acoustic reflex (AR) and a signal-averaging technique to evaluate supra-threshold amplitude characteristics of the AR. By evaluating AR amplitude relationships in a mathematical model based on known afferent, efferent, and central pathway effects, we are able to compare results from a variety of patients and to make meaningful diagnostic interpretations.

Brain Stem↗
PubMed1982

Protein-RNA crosslinking in Escherichia coli 30S ribosomal subunits. Identification of a 16S rRNA fragment crosslinked to protein S12 by the use of the chemical crosslinking reagent 1-ethyl-3-dimethyl-aminopropylcarbodiimide.

1-ethyl-3-dimethyl aminopropylcarbodiimide (EDC) was used to cross-link 30S ribosomal proteins to 16S rRNA within the E. coli 3OS ribosomal subunit. Covalently linked complexes containing 30S proteins and 16S rRNA, isolated by sedimentation of dissociated crosslinked 30S subunits through SDS containing sucrose gradients, were digested with RNase T1, and the resulting oligonucleotide-protein complexes were fractionated on SDS containing polyacrylamide gels. Eluted complexes containing 30S proteins S9 and S12 linked to oligonucleotides were obtained in pure form. Oligonucleotide 5'terminal labelling was successful in the case of S12 containing but not of the S9 containing complex and led to identification of the S12 bound oligonucleotide as CAACUCG which is located at positions 1316-1322 in the 16S rRNA sequence. Protein S12 is crosslinked to the terminal G of this heptanucleotide.

Bacterial Proteins↗
PubMed1982

Auditory brainstem response (ABR) to tone-pips: results in normal and hearing-impaired subjects.

We evaluated predictive accuracy of the auditory brainstem response (ABR) to tone-pip and click signals in normal and hearing-impaired subjects. Prediction of hearing sensitivity based on threshold of the ABR to tone-pips of 500 and 2 000 Hz to clicks was compared to the behavioral results obtained by conventional pure-tone audiometry. Results showed that error in prediction was greatest for the 500 Hz tone-pip and least for the click. In addition, predictive error for the 500 Hz tone-pip varied with the contour of the pure-tone audiogram. In general, greatest predictive error was observed in subjects with steeply sloping audiograms.

Acoustic Stimulation↗
PubMed1980

The effect of degree of hearing loss on diagnostic test strategy: report of a case.

We discuss test results in a single case of eighth nerve disorder. The patient was evaluated twice, once when sensitivity loss was only mild and once when sensitivity loss was severe. Diagnostic contribution of individual test measures depended on degree of sensitivity loss. When the loss was only mild, the acoustic reflex test and auditory brain-stem response (ABR) audiometry were most sensitive to eighth nerve disorder. When sensitivity loss was severe, results of the acoustic reflex test and ABR audiometry became ambiguous. At that time, the more "traditional" audiometric test battery of Bekesy audiometry, suprathreshold adaptation test (STAT), and speech audiometry provided the most useful diagnostic information. Since degree of sensitivity loss at the time of initial evaluation is an uncontrollable variable, diagnostic strategy must include tests appropriate to a wide range of hearing loss.

Acoustic Impedance Tests↗
PubMed1980

Synthesis and properties of N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine, a new reagent for RNA-RNA and RNA-protein cross-linking.

The synthesis of N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine (Gbz-Cyn2-Ac) is described. Like other glyoxal-type reagents it reacts with guanine and arginine. The kinetics and pH dependence of these reactions are studied. (Gbz-Cyn2-Ac) reacts with non-base-paired guanines at about 20 sites in 16-S rRNA. After reduction of disulfide bonds each derivatized guanine residue carries a free -- SH group which can be used to create RNA-RNA bridges or, after introducing an additional photoactivatable derivative, RNA-protein bridges.

Arginine↗
PubMed1980

Effect of degree of hearing loss on diagnostic audiometric tests.

Results of five diagnostic audiometric tests--(1) auditory, brain-stem response (ABR) audiometry, (2) the acoustic reflex (AR) test, (3) speech audiometry, (4) threshold Bekesy audiometry, and (5) supra-threshold adaptation test (STAT)--were examined in sixty cases of confirmed eighth nerve disorder. Test results were classified as either (1) positive for eighth nerve site, (2) negative for eighth nerve site, or (3) ambiguous for site of disorder owing to severity of hearing loss. Findings suggest that degree of hearing loss is an important factor in test interpretation. In general, ability to interpret test results unambiguously decreases as degree of hearing loss increases, especially for sensitive test procedures like ABR and speech audiometry.

Adult↗
PubMed1979

Characterization of preribosomal ribonucleoprotein particles from Tetrahymena pyriformis.

Ribonucleoprotein particles present in extracts of nuclei prepared from Tetrahymena pyriformis labelled for 1, 2.5, 5 and 10 min with [3H]uridine during exponential growth were analysed by sedimentation through linear 10--30% sucrose gradients. After 1 min of labelling, the early ribosomal RNA precursor (36-S) is found to be associated with slowly sedimenting particles which form a broad peak centred at approximately 50 S. Other kinds of particles sedimenting at 80 S, 66 S, 60 S and 44 S are observed when labelling is carried out for longer periods (2.5, 5 and 10 min). The 80-S particle contains 29-S and 18-S RNA species together with traces of 36-S RNA; the 60-S and 44-S particles contain 26-S and 17-S RNAs respectively. Similar results were obtained when [Me-3H]methionine was used for labelling in place of [3H]uridine. Methylation of the RNA present in slowly sedimenting nuclear components (30-70-S) is rapid, reaching a plateau at 5 min while that of the faster sedimenting (70--90-S) components is still increasing after 10 min. Only three types of ribonucleoprotein particles (80-S, 66-S, and 44-S) were observed when the cells were labelled after prolonged starvation. A scheme of ribosome biogenesis based on these results is presented.

Animals↗
PubMed1979

Low-frequency hearing loss in presbycusis. A central interpretation.

Elderly subjects with a central phonemically balanced (PB) and synthetic sentence identification (SSI) pattern show greater low-frequency (LF) sensitivity loss than elderly subjects with a peripheral PB-SSI pattern. This LF hearing loss is not the simple consequence of age, nor does the LF hearing loss account for depressed SSI performance. We conclude that LF sensitivity loss and a central PB-SSI pattern are both components of central aging. We discuss the implications for auditory rehabilitation of elderly subjects.

Aged↗