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Biomedical subjects

M J Collins

Publications and source records attributed to M J Collins.

At least 73 records · Page 4Linked to original sources

Categorical perception of speech sounds via the tactile mode.

The usefulness of tactile devices as aids to lipreading has been established. However, maximum usefulness in reducing the ambiguity of lipreading cues and/or use of tactile devices as a substitute for audition may be dependent on phonemic recognition via tactile signals alone. In the present study, a categorical perception paradigm was used to evaluate tactile perception of speech sounds in comparison to auditory perception. The results show that speech signals delivered by tactile stimulation can be categorically perceived on a voice-onset time (VOT) continuum. The boundary for the voiced-voiceless distinction falls at longer VOTs for tactile than for auditory perception. It is concluded that the procedure is useful for determining characteristics of tactile perception and for prosthesis evaluation.

Adult↗

Reduction of hemifacial spasm and dysarthria following EMG biofeedback.

In this case study, a geriatric patient who had an 18-year history of hemifacial spasm was given EMG-biofeedback-assisted relaxation training. No formal speech therapy was provided. Our results confirmed two hypotheses: (a) The patient would learn to reduce frontalis EMG and facial spasm with and then without biofeedback, and (b) as a result, speech would be markedly improved. At both the 1-month and 15-month follow-up the patient retained the ability to relax his facial muscles with similar carry-over to speech. Possible neurophysiologic mechanisms of action mediating the feedback training are discussed.

Aged↗

Effects of background noise level on detection of tone glides.

Detection thresholds were obtained for short duration rising tone glides and falling tone glides for normal hearing listeners in quiet and with varied levels of background, broadband noise. For signal durations 50 ms, or greater, pure tones were detectable at lower levels than were rising and falling tone glides; no level effects were observed. For signal durations less than 50 ms an interaction between background noise level, signal duration, and signal class was observed. The previously reported tendency for short duration rising glides to be detected at lower sound pressures than pure tones or falling tone glides appears to be unique to a limited range of noise levels (40-75 dB).

Acoustic Stimulation↗

Papovaviral sialoadenitis in athymic nude rats.

A wasting disease was found in 32 athymic nude rats. The rats had parotid sialoadenitis with intranuclear inclusion bodies in ductal and acinar epithelial cells. Other common lesions included bronchitis, bronchiolitis and secondary bacterial pneumonia. Less commonly, rhinitis and Harderian adenitis were seen. Intranuclear inclusions were also seen in bronchial epithelium of 1 rat, Harderian gland acini of 1 rat and laryngeal glands of 2 rats. Viral particles, averaging 45 nm in diameter, sometimes in crystalline arrays, were found in the nucleus of parotid epithelial cells. By the use of the avidin-biotin-peroxidase complex (ABC) immunoperoxidase technique, antibodies to disrupted SV40 virus (the group specific antigen of the polyomavirus (miopapovavirus) genus of the papovavirus family) reacted with intranuclear inclusions and cytoplasm of parotid epithelium and inclusions in lung and Harderian gland. The viral antigen did not cross react with antibodies to mouse polyoma, mouse K or disrupted bovine papilloma viruses.

Animals↗

Tone-glide discrimination: normal and hearing-impaired listeners.

Speech sounds vary rapidly in frequency, and the status of the auditory system might be expected to influence the processing of time-varying signals. Two experiments were undertaken to determine the effect of sensorineural hearing loss on the discrimination of frequency-varying sinusoids which are analogous to second formant transitions and contiguous steady-state portions of consonant-vowel and vowel-consonant syllables. A transformed up-down procedure was used to estimate the difference limen of the glide (transition) portions of the stimuli. In Experiment 1, it was found that three of the four normal hearers exhibited larger difference limens for stimuli with glides preceding fixed-frequency (steady state) portions than for comparable glide-following conditions. Subjects with sensorineural hearing loss did not show this effect consistently. In Experiment 2, the possibility of temporal masking of the glide segment by the fixed-frequency segment was explored. Large individual differences in temporal masking effects were observed for both normal-hearing and hearing-impaired subjects. Temporal masking could account for some, but not all of the differences in discriminability of glide-preceding and glide-following conditions. It appears that audiometrically similar sensorineural hearing losses can differentially affect temporal masking and discrimination of the tone glides.

Adult↗

An ultrastructural study of pale eumycetoma grains.

The electron microscopic appearances of grains from seven patients with pale grain eumycetoma infections have been studied. The infecting fungi were Pseudallescheria boydii (2), Fusarium sp. (1), Acremonium kiliense (1), a non-sporing mould (2) and Trichophyton violaceum (1). P. boydii grown in vitro and grains from a Madurella mycetomatis infection were used for comparison. The most important ultrastructural features of the pale eumycetoma grains were the gross thickening of the fungal cell walls maximal at the periphery of the grain, the predominance of grossly disorganised hyphae and the appearance of cytoplasmic membrane systems. In some areas adjacent cell walls appeared to fuse. These changes may account for some of the well recognised difficulties in isolating organisms from eumycetoma grains and treating the infections with antifungal drugs.

Ascomycota↗

Experimental dermatophytosis: the clinical and histopathologic features of a mouse model using Trichophyton quinckeanum (mouse favus).

We have established a reproducible mouse model of dermatophytosis using Trichophyton quinckeanum. There was considerable variation in the pathogenic potential among 10 different strains of T. mentagrophytes or T. quinckeanum; susceptibility to the infection varied with the inbred strain of mouse used, with BALB/c or BALB/K mice proving to be the most susceptible. The primary infection was characterized by the development of a scutulum or crust consisting of large quantities of dermatophyte mycelium, dense infiltration with neutrophils, but minimal epidermal proliferation. By contrast, a secondary infection initiated 30 days after the primary infection showed different features with early and almost total elimination of fungal elements, a predominantly mononuclear cell response, and epidermal proliferation. If the secondary infection was given at the peak of the primary illness (day 7), there was a mononuclear cell response with epidermal proliferation but fungal mycelium was prominent and not quickly eliminated. The value of this model in investigating the kinetics of the immune response to experimental dermatophytosis is discussed.

Animals↗

Audibility of short-duration tone-glides as a function of rate of frequency change.

Thresholds for rising and falling tone-glides were determined against a background of 50-6000 Hz noise at a level of 60 dB re 20 microPa. Glides were centered around 2000 Hz and changed frequencies linearly at rates of 24, 48, 96 and 192 Hz/ms; tone-glide durations were 5, 10, 20 and 40 ms. Results demonstrate a rate-dependent asymmetry in the detectability of rising and falling tone-glides, with rising tone-glides detected at lower signal intensities for the higher rates of frequency change (i.e., 96 and 192 Hz/ms).

Auditory Threshold↗

Peritoneal macrophage alterations caused by naturally occurring mouse hepatitis virus.

During routine harvest of murine resident peritoneal cells for macrophage function assays the authors recently noted that mice showed a 3-4-fold spontaneous increase in number of peritoneal cells within 1 week of being placed in one of their animal rooms. While the mice appeared clinically normal, the collected macrophages had highly convoluted membranes, showed enhanced spontaneous tumor cell killing, and showed increased erythrophagocytosis. Histopathologic findings included mild peritonitis and occasional foci of individual hepatocyte necrosis. The results of routine murine serologic studies and bacterial cultures of the peritoneal cavity were negative. Immunosuppressed mice placed in this room showed severe hepatic necrosis within 4 days, and ultrastructural particles characteristic of corona virus could be demonstrated in the necrotic foci. Mouse hepatitis virus (MHV) was isolated from these livers. Untreated mice showed positive MHV titers, as detected by the enzyme-linked immunoabsorbent assay (ELISA) after 21 days in the room. This episode demonstrates that MHV have profound effects on macrophage parameters while causing few clinical signs or histopathologic alterations. Secondly, the complement fixation assay for MHV as included in routine viral screens appears relatively insensitive for detecting outbreaks of MHV.

Animals↗

Veterans Administration cooperative study on aphasia: a comparison of individual and group treatment.

Five Veterans Administration Medical Centers participated in an investigation designed to compare individual with group treatment for aphasic patients who had suffered a left hemisphere cerebral vascular accident. Patients who met selection criteria were assigned randomly to either traditional, individual, stimulus-response type treatment of specific language deficits or group therapy designed to improve communication through group interaction and discussion with no direct treatment of specific language deficits. All patients received eight hours of therapy each week beginning at four weeks postonset and continuing until 48 weeks postonset or until they dropped out of the study. A battery of language measures and a clinical neurologic evaluation were administered at intake and every 11 weeks a patient was in the study. Results show both individually and group-treated patients made significant improvement in language abilities. Individual treatment resulted in significantly better overall performance on the Porch Index of Communicative Ability; however, no significant differences were observed between groups on the other language measures. If the traditional belief is correct that significant spontaneous recovery is complete by three to six months postonset, significant improvement in both groups beyond 26 weeks postonset indicates both individual and group treatment are efficacious methods for managing aphasic patients.

Adult↗

Auditory signal processing in a hearing-impaired subject with residual ultra-audiometric hearing.

A number of hearing-impaired individuals with near-normal thresholds for frequencies above 8,000 Hz who are characterized by good speech articulation have recently been identified. It is unclear whether this unusually good articulation is linked to the ability of such persons to process speech signals containing energy that falls within the range of their residual, high-frequency hearing (for example, certain consonants). This paper reports a detailed study of the signal-processing capabilities of one patient with a long-standing, severe to profound hearing loss in the standard audiometric range, and normal left-ear thresholds in the region of 13,000 Hz. Measures obtained include difference limens for frequency and intensity, gap detection, rate matching, temporal integration, and tone-on-tone masking profiles (psychoacoustical tuning curves). In addition, measures of speech production and perception were made when the patient was using an experimental hearing aid designed to transpose speech range frequencies into the region of her residual high-frequency hearing. Results indicate the patient can efficiently process signals which fall within the band of her best hearing, and suggest her ultra-audiometric hearing may be useful in speech communication.

Adult↗

Chronic antigen-antibody-complex glomerulonephritis in mice.

Daily injection of human serum albumin into mice genetically selected to produce low-affinity antibody to protein antigens resulted in a more severe antigen-antibody-complex-induced glomerulonephritis than in mice producing high-affinity antibody. The low-affinity mice had higher levels of circulating antigen-antibody complexes, greater impairment of renal function and reduced reticuloendothelial clearance of 125I-PVP compared to high-affinity mice. Electron microscopy of glomeruli revealed the presence of subepithelial electron-dense deposits in low-affinity mice and predominantly subendothelial-mesangial deposits in high-affinity mice which corresponded to the predominantly capillary staining in low-affinity mice and mesangial staining in high-affinity mice by immunofluorescence. Auto-radiography of electron-microscopy sections demonstrated the presence of antigen in the electron-dense deposits, indicating that these deposits indeed contained antigen-antigen complexes.

Animals↗

Evaluation of a protocol for fitting a wearable master hearing aid.

An experimental protocol for the prescriptive fitting of a wearable master hearing aid was evaluated. The protocol consisted of four stages: (i) acquisition of baseline audiometric data, (ii) fixed test battery using speech-in-noise as the test material, (iii) adaptive adjustments, and (iv) evaluative comparative data. The results showed that systematic improvements in hearing-aid performance were obtained as a result of using the experimental protocol and that the largest improvements were obtained during the fixed-test-battery stage. The protocol in its present form is not clinically practical for most situations.

Audiometry↗

A morphological study of incubated slices of rat cerebellum in relation to postnatal age.

The morphology of incubated slices of cerebellum from rats of various ages between birth and 70-90 days was studied using light and electron microscopy. The slices were prepared using a mechanical chopper and were incubated in Krebs solution for 1 1/2-2 h. Up to 8 days of age, cellular and subcellular damage in the slices was only rarely encountered. At 14 days, the number of pyknotic cells had increased, particularly at the cut edges of the slices, but otherwise the morphology resembled that of the cerebellum fixed in situ. By 21 days, pyknosis and swelling was more extensive, the most vulnerable neurones appearing to be the Purkinje cells and the inhibitory interneurones in the molecular layer, the internal granule cell layer being relatively spared. In slices from the adult, damage had further increased to include more than 90% of the granule cells. This non-uniform preservation of the cells in the slices with respect to age is likely to have a considerable influence on results from developmental studies carried out using mechanically-chopped brain slices. When prepared by hand, using a thin blade and glass guide, slices from the adult cerebellum showed good morphological preservation.

Animals↗