Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0149958 (complex partial seizures)
 2,563 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Guinea pigs were exposed in groups to pure tones of varying frequences (1000, 3000, 5000 cps) and intensities in the range of 85--130 dB SPL. Other guinea pigs were exposed to octave band noise (180--5600 cps). By means of morphology we examined the immediate and late degenerative changes of the cochleae. The changes in sensory and supporting cells were simular after a short time overstimulation (130 db SPL--15 min) compared to a 5-days-stimulation at the 85 dB SPL level. After an OBN-Stimulation with 105 dB SPL--61 hours, lesions of sensory cells were found spread over several coils of the cochleae, with a predominance of the basal and 2nd coil. After pure tone stimulation the destruction of the organ of Corti was not tonotopically related according to the frequencies which were used in the experiments. The circumscribed destroyed areas in the organ of Corti were found mainly in the tonotopical range of the receptors of 2000--5000 cps--this means the end of the basal coil and the 2nd coil. The probable mere influence of direct mechanical stress is discussed.
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PMID:[The acoustic trauma in animal experiment. II. Morphological reaction in the guinea pig cochlea after traumatisation by pure tones and octave band noise (a SEM- and TEM-study) (author's transl)]. 72 86

62 guinea-pigs were treated twice exposed to white noise, 105 dB SPL, 20 to 20 000 cps for 40 minutes with a break of 24 hours in between. The cochlear microphonics (CM), the compound action potentials of the acoustic nerve (NAP) and the slow evoked potentials (SEP) were recorded. There were different degrees of damage to be seen in the acoustic biopotentials. The CM showed little damages only whereas the compound action potentials of the hearing nerve showed significant impairments in excitation and in adaptation. In the SEP excitation was decreased. From this, we may conclude that the CM must not be the only criterion for judging damages in the acoustic system after acoustic trauma. Furthermore we see that the central acoustic pathway is capable to compensate peripheric hearing damages within a short time. An additional exposure to noise does not necessarily add or cumulate the degrees of damage.
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PMID:[A study of damaged acoustic biopotentials in guinea pigs following exposure to white noise]. 80 17

Backward, simultaneous, and forward masking were investigated in 7 normal-hearing adults using a 1-kc/s sinusoid masker of 250 msec duration and 60 db SPL. 10-msec sinusoidal signals (probes) were varied in frequency (.4, .8, .9, .95, 1.05, 1.1, 1.2, 1.6 kc/s) and temporal location, delta t, prior to (-250, -150, -40, -20, -10, -2 msec re: masker onset), during (2, 10, 20, 40, 125, 250 msec re: masker onset), or following (2, 10, 20, 40, 125, 250 msec re: masker offset). The double random staircase psychophysical method (Cornsweet, 1962) was used in all conditions. Monotic thresholds were obtained for the backward and forward masking conditions. Dichotic and monotic thresholds were collected for the simultaneous condition. Results showed: (a) Backward masking. The greatest masking (up to 25 db) occurred between 0.0 and -40 msec when the signal probe was within +/- .2 cps of the masker. There was a linear decrease in masking as a function of delta t; masking effects extended to 250 msec. (b) Forward masking. The data revealed no masking beyond 125 msec delta t, an asymmetry in the masking pattern, relatively large threshold shifts (up to 33 db) when delta t was less than 40 msec and the signal was approximately +/- .2 kc/s within the masker. (c) Simultaneous masking. Overshoot occurred at onset and offset for both dichotic and monotic conditions; onset overshoot was larger in both conditions. The data revealed more forward masking than backward masking at equivalent absolute delta t values. Data were discussed in terms of cochlear vibration patterns and hypothesized central mechanisms.
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PMID:Backward, simultaneous, and forward masking as a function of signal delay and frequency. 718