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PubMedDate not supplied

Effect of a pretest listening exposure on the ascending-descending gap at most comfortable loudness levels.

The effect of approach mode (ascending versus descending, A-D) on comfortable loudness was determined for a 1000 Hz pure tone using Békésy audiometry. Two groups (experimental and control) of 10 normal-hearing young adult subjects measured their most comfortable loudness (MCL) levels pre- and post-treatment. The experimental group received a treatment of a listening exposure to a 70 dB intensity range before the test. The results demonstrated a statistically significant change of the A-D gap in the experimental group while the A-D gap for the control group remained essentially unchanged. It is proposed that MCL is underestimated in the ascending approach and overestimated on the descending testing, which results in the A-D gap. In addition, the results demonstrate the importance of the procedures used in research and clinic of the MCL.

Acoustic Stimulation↗
PubMed2005

Common variations in the pretest environment influence genotypic comparisons in models of anxiety.

The behavioral characterization of rodent strains in different studies and laboratories can provide unreplicable results even when genotypes are kept constant and environmental control is maximized. In the present study, the influence of common laboratory environmental variables and their interaction with genotype on the results of behavioral tests of anxiety/emotionality were investigated. To this end, the inbred rat strains Lewis (LEW) and spontaneously hypertensive rats (SHR), which are known to differ for numerous emotionality-related behaviors, were tested in the open field (OF), elevated plus maze (EPM) and black/white box (BWB), while three environmental factors were systematically controlled and analyzed: (1) the experimenter handling the animal (familiar or unfamiliar); (2) the position of the home cage (top or bottom shelf of the rack) and (3) the behavioral state of the animal immediately before the test (arousal or rest). Experimenter familiarity did not alter the behavior of rats in the OF. Cage position, on the other hand, influenced the behavior in the OF and BWB, with rats housed in top cages appearing less anxious than those housed in the bottom. In the BWB (but not in the OF), these effects were genotype dependent. Finally, the behavioral state of the animals prior to testing altered the results of the EPM in a strain-dependent manner, with some anxiety-related genotypic differences being found only among rats that were aroused in their home cages. This study showed that common variations in the laboratory environment interact with genotype in behavioral tests of anxiety/emotionality. Recognizing and understanding such variations can help in the design of more effective experiments.

Analysis of Variance↗
PubMed1988

Aerial Dispersal and Epiphytic Survival of Pseudomonas syringae during a Pretest for the Release of Genetically Engineered Strains into the Environment.

Prospective experimental field evaluation of genetically engineered microorganisms, such as microbial pest control agents, raises issues of how to properly ascertain their fate and survival in the environment. Field trials with recombinant organisms must reflect requirements for sampling and monitoring. Field trials were conducted at Tulelake, Calif., to monitor the numbers of viable cells of a nonrecombinant strain of Pseudomonas syringae that entered the atmosphere and landed on plants and soil during and after an aerosol spray application. An exponential decrease in numbers of viable cells deposited at increasing distances from three sprayed plots was observed. The relative rate of survival of cells sprayed directly on plants was more than 10 times higher than that of cells dispersed through the air to similar adjacent plants. Results are being used to gain experience with the characteristics of a release site that influence containment or dispersal and to develop appropriate sampling methodologies for evaluating survival and dispersal characteristics of genetically engineered bacteria released into the environment. The ability to make predictions about microbial dispersal and survival will reduce the uncertainties associated with environmental releases of recombinant organisms.

Journal Article↗
PubMed1984

Short term variability in FEV1: relation to pretest activity, level of FEV1, and smoking habits.

The natural variability in forced expiratory volume in one second (FEV1) over 20 minutes was determined in 54 fit hospital employees and 13 patients with restrictive lung disorders. Initial FEV1 ranged from 1.1 to 6.3 1 BTPS. Variability when expressed as absolute change was similar at all levels of FEV1, so that, when expressed as percentage change, variability decreased with increasing FEV1. Smoking habits did not appear to affect variability but activity before the test did. On the basis of these results an absolute change in FEV1 of 190 ml would be necessary for 95% confidence that the change in FEV1 occurred other than by chance in any one individual. This suggests that the absolute change in FEV1 might be a more reliable criterion than percentage change when distinguishing between natural variability and a response to inhalation of bronchodilators.

Adolescent↗