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Biomedical subjects

C Shipley

Publications and source records attributed to C Shipley.

9 recordsLinked to original sources
PubMed1997

Clinical trial of moxidectin oral gel in horses.

A clinical trial carried out over 98 days was done to evaluate treatment of horses with moxidectin gel for efficacy as measured by (1) reduction in the production of parasite ova post treatment, (2) a comparison of the posttreatment parasite egg count suppression of moxidectin to ivermectin, and (3) assessment of the field safety, animal acceptance of the moxidectin formulation, and the utility of the moxidectin delivery device. One hundred and fifty Standardbred horses with naturally acquired parasite infections were used in the study. Moxidectin had more prolonged and greater suppressive influence than did ivermectin on reappearance and magnitude of strongyle egg counts post treatment. Differences were not observed between the capability of ivermectin or moxidectin to reduce and suppress low Parascaris equorum egg counts. Adverse reactions to treatments were not observed, and the utility of the moxidectin delivery syringe and animal acceptance of moxidectin treatment were satisfactory.

Administration, Oral↗
PubMed1991

The effects of articulation on the acoustical structure of feline vocalizations.

Feline isolation calls were analyzed, and a model was developed to relate the acoustical features of these calls to the physical processes used in their production. Fifty isolation calls were recorded from each of five cats for a total sample of 250 vocalizations. By combinations of Fourier transform, autocorrelation, and linear prediction methods, the fundamental frequency (glottal-pulse period) F0, the energy of F0, the frequency having maximum energy Fmax (not always F0), and the energy at this frequency were computed. Mean F0 ranged from 400-600 Hz for individual cats. For some cats F0 was consistent within calls, but for other cats sudden shifts in F0 occurred within calls. Here, Fmax was almost a harmonic of F0 and generally ranged from 1-2 kHz. For individual cats, the energy ratio E = (energy of Fmax/energy of F0) varied from 1 to 60 and the grand average E over the time course of the call varied from about 12 to 38. The mean rms call intensity was an inverted-U function of time. Measured jaw opening was strongly correlated with acoustical features of call. A Bessel-horn model with time-varying flare gave a good account of acoustical parameters such as Fmax. The presence of formantlike resonances in cat vocalizations and the important role of jaw movements (vocal gestures) in the production of these calls suggest that cats may provide a useful model for some aspects of human vocal behavior.

Animals↗
PubMed1988

Thalamic branched and unbranched axons to feline polysensory cortex.

Thalamic afferents to polysensory neocortex of the suprasylvian, anterior lateral, and pericruciate gyri were demonstrated by retrograde axonal transport of wheat germ agglutinin lectin-bound horseradish peroxidase (HRP) and nuclear yellow (NY). Marker injections were placed in areas identified as responsive to auditory stimuli through the use of click-evoked potentials. Both HRP and NY labeled neurons were found in close proximity or in overlapping regions of the rostral intralaminar nuclei and the adjacent ventral lateral nucleus of the thalamus. While thalamic neurons projecting to different polysensory neocortical areas were often in overlapping fields, double labeling was rare. These results indicate that similar auditory responses seen in different cortical polysensory areas are mediated by mainly separate but topographically related populations of thalamocortical neurons. Similarities in auditory response patterns seen across widely separated areas of polysensory neocortex may be due to common inputs relayed through overlapping or adjacent areas of the thalamus.

Animals↗
PubMed1988

Voiced calls evoked by hypothalamic stimulation in the cat.

Voiced vocalizations evoked by hypothalamic stimulation were studied in a series of six awake adult cats. Electrical stimulation was found to evoke vocalizations at numerous sites within the hypothalamus, ranging from A + 8 to A + 16. Regions showing the largest number of responsive sites were the preoptic region, the ventromedial area, the perifornical region, the lateral and the dorso-medial hypothalamus. The form of the evoked calls was generally similar to the spontaneous calls of the same animal. Call latency, duration, and intensity were not significantly affected by changes in stimulus intensity or duration but all three of these call parameters were significantly affected by changes in stimulus frequency. In general, call latency was longest at sites in the rostral hypothalamus and shortest at sites in the caudal hypothalamus. This study is the first to investigate systematically voiced call producing areas in the hypothalamus of awake cats and to document similarities between these calls and spontaneously produced voiced calls.

Animals↗
PubMed1988

The role of auditory feedback in the vocalizations of cats.

The vocalizations of deaf cats were compared with those of littermate hearing controls at 30 days, 50 days, 1 year and 3 years of age. At all ages, deaf cats called more loudly than hearing animals. At 30 days, 50 days, and 3 years, deaf cats called about twice as loudly as hearing animals while at 1 year the calls of the deaf animals were approximately 6 times louder than those of the hearing littermates. Analysis of variance revealed significant differences in call loudness between deaf and hearing animals at 30 days, 1, and 3 years. Deaf and hearing animals did not differ in rate of calling or in the duration of individual vocalizations at 30 days, 50 days, and 1 year. At 3 years, the calls of the deaf animal were shorter than those of the hearing control. The calls of deaf animals were less variable than those of hearing animals at 30 days, 50 days, and 3 years. There was a tendency for the fundamental frequency of the calls of deaf animals to be higher than that of hearing animals at 30 days, 50 days, and 1 year. These results document the importance of auditory feedback in the regulation of feline vocalization.

Age Factors↗
PubMed1984

Binaural interaction effects on the auditory brainstem response of the cat and kitten.

The auditory brainstem response (ABR) is a series of volume conducted potentials that can be recorded from the scalp within 10 ms following auditory stimulation. Differences between ABRs evoked with binaural stimulation and those constructed by summing equivalent numbers of monaural stimulation to each ear indicate the presence of binaural interaction for some ABR potentials but not for others. In the present study, ABR binaural interactions were studied in both cats and kittens. Binaural interactions were not seen for waves 1-3 but were present at the latencies of waves 4, 5 and, in most cases, 6. The sound intensities used were selected to insure that acoustic cross-over, i.e. sound presented monaurally to one ear stimulating the other, did not influence binaural interaction effects. Experiments with cats that had been monaurally deafened confirmed that the effects observed were not due to acoustic cross-over. Systematic manipulation of stimulus rate and intensity produced marked changes in the level of binaural interaction. Increases in stimulation rate from 10 to 100 clicks/s reduced binaural interaction for wave 4 and reversed the direction of binaural interaction for wave 5. Wave 6 was not generally present at rates above 10 clicks/s. Reduction of stimulus intensity reduced binaural interaction for wave 4. Binaural interaction effects were at adult levels in kittens of 20 days for waves 4 and 5. Wave 6 was not present until 30 days of age. These data suggest a possible model of the physiological processes producing binaural interaction which is based on occlusion as seen in other areas of the nervous system. In such a model, convergent input becomes more important in driving the generators of some ABR potentials when the system is stressed (as, for example, by increased stimulus rate), than it is when the system is not stressed.

Age Factors↗
PubMed1980

Brain stem auditory evoked response development in the kitten.

The development of brain stem auditory evoked responses (BAERs), recorded from a surface electrode as short-latency, volume-conducted potentials, was studied in a series of kittens over a postnatal period ranging from birth to 60 days. Repeated, longitudinal observations on particular kittens were supplemented with observations on additional kittens during the first and second postnatal week to determine age of onset of the BAERs. The position of the animal and sound source within the recording chamber were held constant across recording sessions, as was click intensity except during recordings in which intensity effects were specifically studied. Click rates of 1, 10, 50 and 100/sec were routinely presented. Reference electrodes at the tongue, pinna and neck showed volume-conducted responses to the click stimuli and resulted in considerable distortion of the activity recorded by the vertex electrode; the forepaw, in contrast, showed no activity and a vertex-forepaw electrode configuration provided good resolution of the BAERs across development. A number of new observations were made. BAERs were first observed at 4 days of age, approximately the same age at which depth evoked potentials are first recorded in brain stem auditory nuclei. Initially the BAERs were diffuse, high threshold and fatigued rapidly, characteristics shared with depth evoked potentials in the early postnatal period. Over the first two weeks, the potentials showed marked decrease in threshold, increased resistance to fast click rates, and better definition of wave forms. All BAER components showed exponential decreases in latency. Because all of the brain stem evoked potentials could be recorded concurrently and longitudinally in the same subject a number of developmental comparisons were possible among the BAER components. Wave 1, related to the acoustic nerve in the adult cat, showed a developmental time course and adult latency similar to that reported for N1. Wave 2, related to the cochlear nucleus in the adult, showed a marked bimodality over the first month; wave 2a was a large amplitude clearly separated wave which gradually fused as an inconspicuous leading shoulder on wave 2b. Wave 2b developed with a time course and adult latency similar to that reported for the ventral cochlear nucleus. Wave 3, related to the region of the superior olivary complex in the adult, showed a clear but transient bimodality during the third week of development. Wave 5, related to the inferior colliculus in the adult, appeared later than waves 1-4 and showed a significantly slower rate of development than waves 1-4. These data indicate that differential developmental changes occur within the brain stem auditory pathway and that the BAERs provide a dynamic probe of concurrent maturational interactions.

Acoustic Stimulation↗