Enhancement of mutagenicity of 1-nitropyrene by water as a diluent.

The mutagenicity of 1-nitropyrene was strongly enhanced in the Salmonella mutagenicity test with the preincubation modification when it was dissolved in dimethylsulfoxide and diluted with water. The enhancement of mutagenicity was not found in the plate incorporation method and seemed to be common to chemicals which have low solubilities in water. The indications were that the effectiveness of preincubation modification was due to the increased absorption of test chemicals by the Salmonella cells, and that the absorption depends primarily on the solubility of test chemicals in the assay mixture.

Survival of spiral ganglion cells in profound sensorineural hearing loss: implications for cochlear implantation.

Ninety-three temporal bones from 66 patients who were profoundly deaf during life were reconstructed by analysis of serial light microscopic sections. The correlations of total and segmental spiral ganglion cell counts with age, duration of hearing loss and profound deafness, and cause of hearing loss were evaluated. Bivariate analysis demonstrated that total spiral ganglion cell count tended to be lower in older than in younger deaf individuals and lower with longer duration of hearing loss and total deafness. However, multiple regression analysis demonstrated that the cause of hearing loss was the single most significant determinant of total spiral ganglion cell count. Patients with deafness due to aminoglycoside toxicity or sudden idiopathic deafness had the highest residual spiral ganglion cell count and patients with deafness due to presumptive postnatal viral labyrinthitis, bacterial labyrinthitis, and congenital or genetic causes had the lowest numbers of residual spiral ganglion cells.

Dimensions of the extended facial recess.

The variability of the dimensions of the facial recess and extended facial recess with age, sex, and degree of pneumatization was measured in 87 temporal bones serially sectioned in the horizontal plane. Although some statistically significant differences in dimensions were identified, the absolute differences were small compared to the range of measurements. The mean dimensions were very similar in all groups studied. The clinical relevance of the data to mastoid surgery and cochlear implantation is discussed.

Classification of non-nystagmic spontaneous pathological eye movements.

We attempted to classify the well-known spontaneous pathological eye movement (SPEM), to provide a unified nomenclature, to describe its pathophysiology, and to determine its significance in determining a differential diagnosis. Nomenclature was according to the first reporter. These phenomena are easy to confuse with artifact when recording ENGs. A careful analysis which considers history and general neurological findings can identify many of these as true clinical findings which may be as important as nystagmus in the establishing of a clinical diagnosis. Each SPEM, once confirmed, plays a decisive role in the localization of lesions within the central nervous system.