Red cell antibody screening and identification: a comparison of two column technology methods.

Two commercial column techniques for use in antibody screening and identification procedures were tested in parallel with 1000 random samples sent for ante-natal serological investigation. The DiaMed ID microtyping system uses a sephadex gel contained in microtubes, either neutral or impregnated with anti-human globulin (AHG), for use in two-stage enzyme methods and LISS indirect antiglobulin testing (IAT) respectively. The Ortho Biovue technique consists of a slurry of micro glass spheres which act as the filter to retain haemagglutination reactions within the matrix. Columns containing AHG also possess a macromolecular density barrier to prevent test serum from passing into the column and neutralising the AHG. Both systems offer the advantage of 'no-wash' IAT, which minimises the potential for problems and errors associated with conventional spin-tube techniques. In this comparison of the two column methods, antibody detection rates were found to be similar and the sensitivity of both methods was comparable, although the Biovue technique was prone to exhibit equivocal results, particularly in the IAT.

Ipsilateral, contralateral, and binaural masking effects on the human brain-stem auditory-evoked responses to click stimuli.

Two experiments concerning the effects of continuous broadband noise on wave V of the click-evoked human BAER are reported. Experiment I compared the effects of broadband masking noise presented ipsilaterally, contralaterally, and biaurally on the BAER to 100-dB pSPL monaurally presented clicks. For noise levels up to 75 dB SPL, contralateral masking had no effect on either the latency or the amplitude of wave V. Ipsilateral and binaural noise levels above 35-45 dB SPL increased wave V latency and decreased its amplitude, and the magnitudes of these effects were similar for ipsilateral and binaural noise conditions. Experiment II compared the effects of broadband masking noise on wave V to 100-dB pSPL clicks presented monaurally to each ear, and binaurally, with the noise being presented to the ear(s) of click presentation. In agreement with experiment I, noise levels above 35-45 dB SPL increased wave V latency and decreased wave V amplitude. There were no significant differences for right versus left ear. Wave V latency did not vary significantly for monaural versus binaural presentation, while wave V amplitude was larger for binaural than monaural presentation modes for all noise-level conditions.

Roving-level tone-in-noise detection.

The detectability of tones, or of intensity increments to tones, in bands of random noise was measured for conditions in which the overall level was fixed or was randomly roved from interval to interval of every experimental trial. The purpose of the within-trial rove was to limit the usefulness of a detection strategy based on overall level or level within a single "critical band." At "supracritical" bandwidths, the functions relating masked threshold to noise bandwidth for the roved conditions were similar to those obtained when no rove was employed. At "subcritical" bandwidths, thresholds were higher in some roved conditions, but, for the largest rove, were still lower than would be predicted from arguments based purely on level detection--with one exception. A comparison of observer performance relative to the statistical limits imposed by the roving-level procedure indicated that the traditional critical-band energy-detector model could not account for the results, which are attributed to discrimination based on spectral shape or on waveshape.