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Biomedical subjects

T Gay

Publications and source records attributed to T Gay.

At least 37 records · Page 2Linked to original sources
PubMed1987

Non-pulmonary Rhodococcus equi infections in patients with acquired immune deficiency syndrome (AIDS).

Rhodococcus equi, formerly known as Corynebacterium equi, was isolated repeatedly from the blood of two patients with the acquired immune deficiency syndrome (AIDS). Neither of the patients had pneumonia while they were bacteraemic, whereas pneumonia has been present in all previously reported cases of human infection with R equi. One of our patients had diarrhoea and the organism was isolated from a stool culture; the other patient had a large granulomatous soft tissue mass in his pelvis caused by R equi. Both isolates were resistant to penicillin and one produced a beta-lactamase. Both patients were treated with vancomycin but only one recovered.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The spectral properties of temporomandibular joint sounds.

Spectral analyses were performed on sounds recorded from TMJ's that had previously been classified into different intracapsular categories, in an attempt to determine whether the inherent properties of these sounds were unique for each different disorder. A total of 55 joints was studied: 32 were diagnosed as displaced disc with reduction [DDR], 10 were diagnosed as displaced disc without reduction [DDN], and 13 were diagnosed as degenerative joint disease [DJD]. The spectral analysis for each recorded joint sound was performed using a Fast Fourier transform routine, the results of which were plotted as a frequency vs. amplitude envelope. These analyses showed that different intracapsular TMJ disorders were characterized by sounds whose energy distribution patterns, while showing certain across-group differences, usually shared significant common spectral properties. The joint-propagated noises associated with DDR, DDN, and DJD were each characterized by a spectral envelope whose primary band of energy was centered around a peak at approximately 1 kHz, and which dropped off from that point to background levels. These patterns presumably reflect the resonance characteristics of the disordered joint as defined by the mass and stiffness of its articulating surfaces. Based on the findings of this study, it would appear that comparisons of the spectral envelopes of joint-propagated sounds would have only limited application in the differential diagnosis of intracapsular TMJ disorders.

Adolescent↗
PubMed1982

Anticipatory labial coarticulation: experimental, biological, and linguistic variables.

The research reported here represents an attempt to resolve the differences between two views of anticipatory labial coarticulation. One of these views contends that a speaker begins labial movement toward a rounded vowel in direct relation to the amount of time available, while the other view posits an onset of movement that is temporally locked to the rounded vowel. Electromyographic signals were sampled from four muscles associated with labial movement while, simultaneously, movements of the upper lip in the anterior-posterior and vertical dimensions were recorded. Four native speakers of American English and five native speakers of Swedish served as subjects. Results suggested that (1) there are a number of purely biological and experimental variables which can intrude upon research of this type, and (2) there are also language-specific differences in the production of rounded vowels which suggest that Swedish and American English speakers have learned different motor-programming goals. This second observation is discussed in terms of acoustic/perceptual needs of the speakers of a language.

Adult↗
PubMed1982

Clenched jaw jerks in children.

Masseter muscle silent periods were assessed in 24 children divided into three groups according to their stage of dental development (primary, mixed, and permanent). Surface electrode EMG data, timing code, and microphone input were recorded on magnetic tape. A visual record was obtained by playing the tape into an optical oscillograph; measurements were made from the photosensitive paper. The results indicate the latency and silent period durations of clenched jaw jerks were similar among the three groups. For the subjects in this study, the mean latency and silent period durations of the masseter muscle during clenched jaw jerks were 14.9 ms (milli-seconds) and 27.0 ms.

Adolescent↗
PubMed1981

Parameters of open-close-clench cycles in children.

The results of this study indicate that the latency and silent periods of OCC cycles do not vary among groups representing distinct dentitional stages. The mean latency period durations obtained from the OCC cycles of the subjects in this study ranged from 16.6 to 19.5 msec and demonstrated the smallest SD of all parameters measured. The mean silent period durations ranged from 11.6 to 15.4 msec. Since the neurophysiologic responses do not vary, the reflex elicited by tooth contact in OCC cycles is not based on tooth form or quantity. The results further indicate that, with the exception of the latency period of the anterior temporal muscles, the activities of the right and left components of the masticatory muscles examined are significantly correlated to each other during OCC cycles. This suggests a role for the anterior temporal muscle in bringing about adjustments of the masticatory system in the intercuspal position.

Adolescent↗
PubMed1981

Production of bite-block vowels: acoustic equivalence by selective compensation.

Acoustic and articulatory data are reported for steady state vowels produced both normally and with a bite block. The formant patterns of the bite-block vowels were found to approximate those of the naturally spoken vowels. Measurements derived from lateral view still x-ray films showed that the bite blocks induce drastic articulatory reorganization. Using a mandibular frame of reference, we found that speakers compensated for a large bite block by using supershapes of the tongue and the lips (for [u] and [o]). Comparing the two productions using a maxillary frame of reference, we noted that compensation was maximum at the points of maximum constriction and incomplete or partial at points where the vocal-tract area was large. A computer simulation of our speakers' compensatory strategy revealed that they behaved optimally according to acoustic theory. These findings suggest that a vowel target is coded neurophysiologically in terms of acoustically significant area-function, specifically, by information related to cavity configuration at points of maximum constriction.

Adult↗
PubMed1981

Mechanism in the control of speech rate.

Mechanisms of speech rate control are discussed from the point of view that unidimensional models are inadequate to explain the extensive physiological and acoustical effects observed during changes in speech rate. Evidence is presented to demonstrate that changes in speech rate can result in changes in segmental duration, articulatory displacement, articulatory velocity, and intrasyllabic coarticulation, and that these changes represent nonlinear transformations produced by a reorganization of speech motor strategies.

Electromyography↗
PubMed1979

Temporal aspect os articulatory movement for /s/-stop clusters.

Cinefluorographic tracking of pellets on the tongue body, tongue tip, jaw, and lips of three subjects indicates that there are certain basic strategies used for initial /sp/, /st/ and /sk/ clusters. The data reveal an economy of effort in tongue movement, and support the concept of the tongue as a multiple articulator. In addition, the shorter fricative duration of /s/ before /p/ is seen to be a result of early lip closure relative to the occlusions for /st/ and /sk/, which are delayed due to tongue involvement with the /s/.

Humans↗
PubMed1978

On the production of low tongue tip /s/: a case report.

X-ray motion pictures and electromyography were combined to record tongue movement and tongue muscle activity of a normal speaker during /s/ production. The /s/ was in /i/, /alpha/, and /u/ vowel environments and in two and three consonant clusters. Lead pellets attached to the tongue tip and dorsum were tracked by frame-by-frame analysis of the X-ray film. Recordings from the tongue muscles were graphed and compared with the movement data. Results demonstrate that this subject produces /s/ with the tongue tip down behind the lower incisors and the blade elevated toward the alveolar ridge. EMG data from the tongue shows that the tongue tip depression is not passive but is an active part of the motor strategy used by this subject to elevate the tongue body. These findings suggest that speech pathologists might well include the tip-down strategy of /s/ production in the therapeutic process as an alternative to the tip-up /s/.

Action Potentials↗
PubMed1978

Effect of speaking rate on vowel formant movements.

The purpose of this experiment was to study the effects of changes in speaking rate on both the attainment of acoustic vowel targets and the relative time and speed of movements toward these presumed targets. Four speakers produced a number of different CVC and CVCVC utterances at slow and fast speaking rates. Spectrographic measurements showed that the midpoint format frequencies of the different vowels did not vary as a function of rate. However, for fast speech the onset frequencies of second formant transitions were closer to their target frequencies while CV transition rates remained essentially unchanged, indicating that movement toward the vowel simply began earlier for fast speech. Changes in both speaking rate and lexical stress had different effects. For stressed vowels, an increase in speaking rate was accompanied primarily by a decrease in duration. However, destressed vowels, even if they were of the same duration as quickly produced stressed vowels, were reduced in overall amplitude, fundamental frequency, and to some extent, vowel color. These results suggest that speaking rate and lexical stress are controlled by two different mechanisms.

Acoustics↗
PubMed1975

Post-jejunoileal-bypass hepatic disease. Its similarity to alcoholic hepatic disease.

The authors studied serial hepatic biopsies of five patients who developed hepatic failure following jejunoileal bypass for extreme obesity, with autopsies of two. The hepatic histologic changes included centrilobular or focal alcoholic hyalin, intrasinusoidal collagenosis, fatty hydropic degeneration, and neutrophilic infiltrate. At least two of the patients were abstinent from alcohol, both prior to and after the surgical procedures. The others, after the bypass procedures, had reduced alcohol consumption from previous levels. All patients developed hepatic failure and histologically progressive hepatic disease with alcoholic hyalin and other changes indistinguishable from alcoholic hepatic disease in 21/2 to 5 months, in spite of hyperalimentation and re-establishment of intestinal continuity in four. Nausea, vomiting, abdominal pain and ascites were prominent complaints. Four of the five patients died in hepatic failure. The authors conclude that these cases of progressive hepatic disease with histologic changes simulating those found in livers of alcoholic patients offer evidence that heavy alcohol consumption may affect the liver in an indirect fashion.

Adult↗