[Precocious maturation of auditory evoked potentials in prematures: influence of gestational age and sex].

In humans, the onset of the auditory function occurs at the beginning of the third trimester of pregnancy. Brainstem auditory evoked potentials (BAEPs) can be recorded in preterm neonates as early as 25-26 weeks of gestational age. The latency of BAEP waves show a significant decrease according to increasing age to achieve adult values at the end of the first month after birth for wave I and near 3 to 5 years old for waves III and V.

[Study of the ototoxicity of amikacin and netilmicin using provoked acoustic oto-emissions and high-frequency audiometry].

To compare the ototoxicity of amikacin and netilmicin, tone audiometry, high-frequency audiometry, early auditory evoked potentials, and evoked otoacoustic emission testing were used to evaluate 30 patients (15 under amikacin and 15 under netilmicin). Ototoxicity was not significantly different in the two groups.

Auditory brainstem response (ABR) latency: relative importance of age, sex and sensorineural hearing-loss using a mathematical model of the audiogram.

Influences of age, sex and audiogram on ABR latencies have been studied. Using a mathematical model of audiogram, the analysis of data finds a relative importance of age, sex and audiogram similar to previous studies. Audiogram slope was correlated only with the latencies of waves I and V, and multiple regression analyses indicate the slope effect is relatively weak compared to that of the other parameters.

Differential maturation of brainstem auditory evoked potentials in preterm infants according to birthweight.

Brainstem auditory evoked potentials (BAEPs) were recorded from 39 preterm infants, divided into 3 groups: small-for-gestational-age, with a birthweight less than or equal to 1500 g (SGA); appropriate-for-gestational-age, with a birthweight less than or equal to 1500 g (AGA1); and appropriate-for-gestational-age, with a birthweight higher than 1500 g (AGA2). A significant shortening of the I-V interval due to an increase in wave I latency was found in the SGA group. The lower-weight AGA group (AGA1) was never significantly different from the SGA group.

Electro-optical studies on synthetic polyelectrolytes. IV. Electric polarizability and conformation of poly-N-methyl-2-vinylpyridinium bromide in aqueous solution.

Measurements of the relaxation time on aqueous solutions of the title polyelectrolyte as a function of the concentration and of the molecular weight show that its conformation at very high dilution can be better accounted for by a weakly bending rod or wormlike chain model, with persistence length ranging from 200 to 400 A. The analysis of the field strength dependence of the electric birefringence yields electric polarizability values which increase sharply with the dilution and are not significantly dependent upon the molecular weight. This has been tentatively interpreted on the basis of the theories derived by Oosawa and by Mandel and Van der Touw.