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C R Mitchell

Publications and source records attributed to C R Mitchell.

25 records · Page 2Linked to original sources
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Inner ear pathology in the Palmerston North autoimmune strain mouse.

The Palmerston North autoimmune strain mouse is a model for spontaneous systemic lupus erythematosus. Inner ear structure and function were examined during the onset and progression of systemic autoimmune disease to identify potentially correlated auditory system pathology. The onset of systemic disease occurred at 4 to 5 months of age and was characterized by elevated serum immune complexes, cryoglobulins, and antinuclear antibodies. Coincident with the onset of autoimmune disease was degeneration of the apical turn stria vascularis and outer hair cells. These cochlear changes progressed basalward. At 10 months of age, auditory brainstem response thresholds were elevated and the stria vascularis area was measurably smaller throughout the cochlea. Immunohistochemical staining showed immunoglobulin G deposits within the organ of Corti, the vas spirale of the basilar membrane, the scala tympani, and marrow cavities of the bony otic capsule. These results suggest that cochlear pathology may be immune mediated in this mouse, which would make the strain suitable for the study of the mechanisms relating inner ear abnormalities and autoimmune disease.

Age Factors↗
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The use of a 56-stimulus train for the rapid acquisition of auditory brainstem responses.

To further develop a multiple stimulus method for the rapid acquisition of auditory brainstem responses (ABRs), a 56-stimulus train was tested in mice. Stimuli in the train were tone bursts spaced at 0.5-octave intervals from 4 to 32 kHz. ABR thresholds, latency-intensity and amplitude-intensity functions were obtained using stimuli presented singly (one at a time) and using the 56-stimulus train. Responses from stimuli presented singly and those obtained using the 56-stimulus train were compared. There were no significant differences in thresholds (0.01 level) and very small differences in response latencies and amplitudes. These findings demonstrate the feasibility of multiple stimulus trains for the rapid acquisition of ABRs.

Animals↗
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Reliability of auditory brainstem responses from sequenced high-frequency (> or = 8 kHz) tonebursts.

An auditory brainstem response method is described for evoking responses to 4 high-frequency (8, 10, 12 and 14 kHz) tonebursts in the same amount of time normally required to obtain responses to single tonebursts. Reliability of responses to high-frequency toneburst stimuli presented in the conventional manner (one at a time) has been previously documented. In the present study, high-frequency tonebursts were presented to 20 normal-hearing subjects singly and in a 4-stimulus sequence. The reliability of resulting responses did not differ significantly between single- and multiple-stimulus test conditions. It is concluded that this sequenced-stimulus concept could be developed for use in serial monitoring of individuals receiving ototoxic agents as well as being broadly applicable to clinical situations in which patients cannot or will not respond voluntarily.

Acoustic Stimulation↗