Biomedical subjects
Publications and source records attributed to D E Crowley.
Cochlear potentials measured in several species of lizard show a close correlation between maximum electrical output and number of hair cells, whereas there is no uniform relation to sensitivity. These results are interpreted as indicating structural differentiation and frequency discrimination in spatial terms in the more advanced lizard ears.
A questionnaire on the clinical use of electrocochleography (ECochG) was distributed to clinics throughout the world which use this method. The 26 replies comprised 3696 cases with a median age of 22.5 years. The majority (57.1%) were tested with a transtympanic promontory electrode. The risk of any undesirable effect from this electrode placement was negligible (less than 0.1%), but a greater probability (less than 1.0%) of serious complication from general anesthetics was revealed. On the benefit side, ECochG added significant information to the diagnoses of 87.8% of the children and 34.2% of the adults, and in 48.2% of the children and 2.0% of the adults this information was a primary factor in the hearing evaluation and decision on management. The cases for which ECochG was most helpful were predominantly children and neonates with complex neurological or psychiatric problems which interfered with reliable testing by other methods. Comparisons of ECochG with other methods were reported in 63.2% of the cases. The respondents judged 97.4% of those comparisons to reflect favorably on the validity of ECochG.
A conference was held to consider conceptual issues, methodological problems and preliminary findings related to auditory research with aging animals. Current concepts from various areas of experimental gerontology were discussed in relation to research on the aging auditory system and to the problem of human presbycusis.
A constant anthropogenic release of cadmium to the environment has resulted in a continuous buildup of Cd in soils. Uptake and accumulation of Cd in plant tissue and in grains may lead to food chain transfer to humans. Application of synthetic chelates was suggested to increase metal mobilization and facilitate phytoextraction as a means for the remediation of metal-polluted soils. However, most of the chelate-extracted metal may be leached rather than mobilized to plant roots. In contrast to the synthetic chelates added to soils, plant-produced chelators called phytosiderophores (PS) are excreted directly to the rhizosphere. Previous studies have shown that PS facilitate uptake of Zn and Fe by graminaceous plants. In this study, a two-step PS mediation of Cd uptake was hypothesized: (i) extraction and chelation in the soil solution, and (ii) delivery of the chelated Cd to the uptake system of the plant. We examined Cd extraction by PS, the synthetic chelate HEDTA [N-(2-hydroxyethyl)-ethylenediaminetriacetic acid], and a fungal siderophore rhizoferrin from solid-phase Cd phosphate at pH 7.3 with and without Fe competition in the presence of Ca and Mg as additional competing metals. While rhizoferrin did not extract Cd, PS and HEDTA did extract Cd even in the presence of Fe. Yet, uptake of Cd by wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants was not significantly influenced by Fe stress, but instead was controlled primarily by Cd2+ activity in solution. These results suggest that even though Cd may be mobilized by PS, there is no significant uptake of the Cd-PS complex by the plant roots.