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Biomedical subjects

M J McCutcheon

Publications and source records attributed to M J McCutcheon.

12 recordsLinked to original sources
PubMed1992

Esophageal speaker articulation of /s,z/: a dynamic palatometric assessment.

Esophageal talker linguapalatal contact patterns and durations during /s/ and /z/ productions were examined using dynamic palatometry instrumentation. It was found that sibilant groove narrowing is a physiologic compensation for a reduced air supply in esophageal speech. The place of esophageal /s, z/ articulation was on the anterior portion of the alveolar ridge as seen in normal speakers. Average medial groove width for esophageal /s/ was narrower than the 5-7-mm groove characteristic of normal speakers. Groove widths averaged 3 mm for /s/ and 4 mm for /z/. Systematic changes in groove widths across speech sounds, syllable position, and vowel context were also observed. Use of a narrower lingual groove was interpreted as a significant articulatory maneuver to meter out a limited intraoral air supply and effect more normal fricative durations.

Articulation Disorders↗
PubMed1992

Temporomandibular joint sounds and condyle/disk relations on magnetic resonance images.

This study compared the condyle/disk relationships on magnetic resonance images (MRIs) in a group of subjects with completely silent temporomandibular joints (TMJ) when tested clinically with those in subjects with readily discernible TMJ sounds. The sounds were recorded with an accelerometer as the transducer. Selected degrees of jaw separation were electronically determined and recorded with interocclusal wafers for use with the imaging process. Of the "silent joints" 89% were found to have sounds when tested with the accelerometer. These "subclinical" sounds tended to be of shorter duration and occurred at a greater degree of vertical opening than the clinically discernable sounds. The MRIs of the group with clinically discernable sounds tended to show a change in the relationship between the head of the condyle and the intermediate zone of the disk, at the degree of jaw separation of the sound occurrence, whereas no condyle/disk change occurred in the group with "clinically silent joints." It is likely that all joints create sound during function. The different characteristics of the subclinical sounds versus the clinical sounds may indicate differing sound origins.

Adult↗
PubMed1991

Immunofluorescence-digital image processing system for the quantitation of secreted immunoglobulin by single cells.

To quantitate the amount of secreted immunoglobulin (Ig) by a single cell, the immunofluorescence digital image processing (IDIP) system was adapted to the modified enzyme-linked immunospot (ELI-SPOT) assay. In this assay, an immunofluorescence (tetramethylrhodamine isothiocyanate) conjugated antibody was used for the detection of spots instead of the usual method of enzyme coupling. We have named this the immunofluorescence-linked immunospot (ILISPOT) assay. In addition to the quantitation of secreted Ig by single cells, this method allowed us to objectively determine the exact number of Ig producing spot forming cells (SFC). 96 well culture plates were pre-coated with goat anti-mouse Ig. The mouse IgM producing hybridoma (E-3-4) was incubated in the plates for 4 h at 37 degrees C. Cells were removed prior to the addition of biotinylated goat anti-mouse mu antibody. After overnight incubation, immunofluorescence conjugated avidin was added for the visualization of spots by the IDIP system. The IDIP system consists of a fluorescent microscope equipped with a video camera and computer. The gray scale of secreted IgM was initially established as a standard by the known amount of purified IgM. By using digital image processing, the number of spots and the gray scale of individual spots were computed. The shape and pattern of gray scale data were used to distinguish between the real spots and pseudo spots. This IDIP system could detect as little as 0.19 pg of secreted IgM (1.2 x 10(5) molecules) and an average of approximately 1.33 pg (8.3 x 10(5) molecules) produced by a single cell. Adaptation of the digital image processing system to the ILISPOT assay allowed the measurement of both the amount of Ig produced at the single cell level and also the exact numbers of SFC present in a totally objective fashion.

Animals↗
PubMed1988

Electrical impedance in assessing human body composition: the BIA method.

Fundamental aspects of the body impedance analysis (BIA) method were investigated to determine limitations. This method measures body impedance with a low-level (800 microA) 50-KHz current conducted through the tissues. A linear regression equation was proposed to relate impedance measurements to total body fat. The hydrostatic densitometric method (underwater weighing) was used to validate the proposed mathematical expression. A correlation coefficient of 0.98 between these two methods was obtained. The overall results from this study indicate the usefulness of the BIA method in determining percent body fat in humans provided body fluids are not perturbed several hours before the measurements.

Adipose Tissue↗
PubMed1987

The development of skill in producing word-final English stops.

This study examined production of word-final English /p/ and /b/ by subjects whose native language does not possess voiced stops in word-final position. Native Chinese adults resembled native English adults, native English children, and native Chinese children in producing /p/ with greater peak oral air pressure than /b/. However, unlike subjects in the other groups, the Chinese adults' /b/ was sometimes misidentified as /p/. This may have occurred, at least in part, because the Chinese adults produced a much smaller difference between /p/ and /b/ in labial closure duration and voicing than the other subjects. The English adults sustained voicing in /b/ significantly longer than subjects in the other three groups. To help determine the basis for this ability, the shape of oral air pressure waveforms was examined systematically. The percentage of "delayed" and "bimodal" waveforms, in which pressure stopped increasing, or decreased, prior to the release of labial constriction, was calculated for each group. Only the English adults showed more such waveforms for /b/ than /p/. Voicing continued 18 ms longer in /b/ tokens with delayed and bimodal waveforms than in tokens in which oral pressure increased continuously. The duration of closure voicing was correlated with the rate at which pressure increased in the English adults' /b/ waveforms. Previous aerodynamic modeling has shown that delayed and bimodal waveforms may result from an active enlargement of the supraglottal cavity. This, together with the pattern of between-group differences observed here, suggests that the English adults learned to enlarge the supraglottal cavity to sustain voicing in /b/. It appears that neither the children nor the Chinese adults had as yet acquired this skill.

Adult↗
PubMed1979

Fluorescence intensity resolution in flow systems.

The factor which can limit fluorescence intensity resolution in a flow cytometer of the type in which cells pass perpendicularly through a focussed laser beam depends on signal intensity. For the brightest sources (e.g. fluorescent DNA stains), the coefficient of variation (CV) is limited in our system to around 3% by stream hydrodynamics, unstable illumination intensity, nonstoichiometric staining, etc. The weakest detectable sources (e.g. fluorescent cell-surface labels) are limited in coefficient of variation by shot noise in the photomultiplier due to constant background light levels. Finally, over a fairly wide brightness range between these extremes, resolution is determined primarily by photoelectron statistical variation on the signal itself (i.e. "photon statistics"). Thus photon collection and detection efficiency (solid angle, barrier filter passband, detector quantum efficiency) become of primary importance.

Cells↗
PubMed1977

Measurement of cytoplasmic fluorescence depolarization of single cells in a flow system.

We have built a flow system in which we can analyze and sort individual viable cells on the basis of their cytoplasmic microviscosity. The average cytoplasmic microviscosity (or cytoplasmic structuredness) of a cell can be quantitated by exciting fluorescein molecules in the cytoplasm of the cell with a polarized light source and measuring the extent of depolarization of the fluorescent signal. Changes in the state of a cell (e.g., the reception of a signal inducing the cell to differentiate) often appear to be associated with changes in cytoplasmic microviscosity, these changes being detectable within hours of the inducing signal. An example of one such change is presented.

Bone Marrow↗
PubMed1975

Dynamic palatometry.

A computer-based instrumental system is described for continuous palatometry. Thin pseudopalatal plates (approximately 0.2 mm) with embedded electrodes are used to detect linguapalatal contact during speech articulation. Geometric configurations of such contacts are then derived and displayed to reveal articulatory characteristics.

Computers↗
PubMedDate not supplied

MR imaging of the vocal tract during vowel production.

Modeling of vocal tract behavior during speech production requires accurate measurements of the entire vocal tract. To accomplish this, magnetic resonance (MR) imaging was performed on a 0.5-T system with a custom-made, double-loop, wrap-around coil. A midsagittal section of the region from the glottis to the lips was imaged during sustained production of five American English vowels. A gradient-spoiled gradient-echo sequence was used to achieve a 4-second imaging time. Images showed clear profiles of the entire vocal tract and exhibited essential articulatory features of vowel production. It was possible to measure midsagittal widths at various points along the vocal tract with 1-mm resolution. The measurements were used to construct a tube model for prediction of the acoustic output of the vocal tract. It is concluded that risk-free MR imaging promises to be an important means of acquiring data for vocal tract modeling, with applications to speech pathology, linguistics, and artificial speech.

Humans↗
PubMedDate not supplied

The design of a microcomputer-controlled voice onset time analyzer.

In spoken syllables such as "ta," the interval between the release of the tongue constriction for the stop consonant /t/ and the onset of the vowel is called voice onset time, or VOT. Voice onset time is an important determinant of whether the initial consonant will be heard as a /t/(values of 60-90 ms) or as a /d/ (values of 0-30 ms). VOT information, immediately following a spoken syllable, can provide a speaker with feedback for modifying speech production. Such information can help the hearing-impaired learn to speak. It may also help people who learn English as a second language, since they often produce /b,d,g/ and /p,t,k/ with inappropriate VOT values. A prototype portable device measures VOT for initial voiced and voiceless stop consonants (e.g., "da" and "ta"). A dual-microphone method is used for acoustic measurement. A microphone in front of the mouth picks up the radiated acoustic signal; another over the larynx transduces vocal vibrations that mark the beginning of a vowel. Analog circuits process the transducer signals and provide gain and filtering. Filters were designed on the basis of the acoustic properties of stop consonants. The output from each analog circuit is fed to a comparator that compares the signal level with a fixed threshold voltage reference. A digital timer starts when the amplitude of the oral signal voltage exceeds a threshold and stops when the laryngeal signal voltage exceeds a threshold. VOT values obtained by the device were compared with those made from digital waveforms of words spoken by five talkers.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗