Using 97 male albino guinea pigs and applying electrophysiological methods, the effects of a 6 kHz tone were investigated at a moderate sound pressure level to the inner ear during a 24-h exposure time. Following exposure to the 6 kHz tone at 90 dB, cochleas showed decreased maximum output voltage of cochlear microphonics (CM) and action potential (AP). In the endolymph, K+ ion and Na+ ion concentrations remained unchanged during 40 min anoxia and 90 dB tone exposure. At 80 dB sound exposure decreases in maximum output voltage of CM and AP and decreases in the absolute value of EP could not be detected. Endolymph K(+)-ion Na(+)-ion concentrations were also unchanged. These findings indicate that diffusion potentials are induced at the same time as decreases of maximum output voltage in CM induced by exposure to sound at 90 dB.
A regional epidemic of aseptic meningitis caused by echovirus 30 (E30) occurred in Hokkaido, Japan, during the period of August-December 2017. To investigate their phylogenetic relationship to other human enteroviruses, we determined the complete genomic nucleotide sequences of isolates from this outbreak. Phylogenetic analysis of the viral capsid protein 1 gene showed that the strains were most closely related to E30 strains detected in Germany, France, and Russia in 2013. In contrast, the region encoding the viral protease and the RNA-dependent RNA polymerase had a close phylogenetic relationship to non-E30 enteroviruses detected in the United Kingdom and Switzerland in 2015-2017, suggesting that a recombination event had occurred.
In an attempt to describe the characteristics of febrile convulsions (FC) 133 children with a history of FC were checked neurologically at health centers in northern Japan. Using categorical data from principal component analysis, family history of FC, recurrence and body temperature prior to convulsion, EEG disorders, exogenous factors, age at onset as the principal components were extracted. A quantitative and qualitative analysis of EEG showed that children with FC had more paroxysmal and basic abnormalities, that the rate of appearance of theta wave was more common and of alpha wave was less common, and that mean values of frequency ranges of theta and alpha wave ranges together were significantly lower in the background activity than those of control group children.
The electrophysiological study of cochlear microphonics (CM), whole nerve action potential (AP) and endocochlear potential (EP) were examined. (1) With the extension of the exposure time of 500 Hz tone, a decrease of CM maximum output voltage in test frequency from 2 to 6 kHz was observed. (2) N1 potential of AP decreased very significantly by 500 Hz tone exposure. (3) A very pronounced decrease of the absolute value of the negative potential of the EP in 500 Hz exposure was seen.
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