Biomedical subjects

D Wildman

Publications and source records attributed to D Wildman.

4 recordsLinked to original sources

PubMed1998

A novel experimental apparatus to study the impact of white noise and 1/f noise on animal populations.

This paper reports on the design and construction of a novel apparatus that allows a set of aquatic microcosms to experience complex temporal environmental fluctuations. Replicate microcosms were maintained in 18 water baths with independent environmental controls. We give results from a preliminary experiment designed to look at the effects of varying temperatures with different variance spectra (i.e. white noise or 1/f noise) on single species population dynamics. Matching time series (with identical elements, differently ordered) of environmental temperatures with different Fourier spectra were created for use as input to the apparatus using a novel spectral mimicry method. The apparatus functioned well during the course of the experiment making this an extremely useful research tool. This apparatus now provides ecologists with a means of studying how environmental variability and directional trends in this variability, are filtered and translated by real populations and micro-ecosystems.

Animals↗

PubMed1995

Coupling of bitter receptor to phosphodiesterase through transducin in taste receptor cells.

The rod and cone transducins are specific G proteins originally thought to be present only in photoreceptor cells of the vertebrate retina. Transducins convert light stimulation of photoreceptor opsins into activation of cyclic GMP phosphodiesterase (reviewed in refs. 5-7). A transducin-like G protein, gustducin, has been identified and cloned from rat taste cells. We report here that rod transducin is also present in vertebrate taste cells, where it specifically activates a phosphodiesterase isolated from taste tissue. Furthermore, the bitter compound denatonium in the presence of taste-cell membranes activates transducin but not Gi. A peptide that competitively inhibits rhodopsin activation of transducin also blocks taste-cell membrane activation of transducin, arguing for the involvement of a seven-transmembrane-helix G-protein-coupled receptor. These results suggest that rod transducin transduces bitter taste by coupling taste receptor(s) to taste-cell phosphodiesterase. Phosphodieterase-mediated degradation of cyclic nucleotides may lead to taste-cell depolarization through the recently identified cyclic-nucleotide-suppressible conductance.

Animals↗

PubMedDate not supplied

Assessing disease prevalence from inaccurate test results: teaching an old dog new tricks.

Estimates of disease prevalence are needed for the interpretation of test results as well as for public health decisions. Assessing prevalence may be difficult if a definitive test is unavailable, impractical, or expensive. A formula derived from Bayes' theorem can calculate the prevalence of disease in a population by incorporating test results with a knowledge of the sensitivity and specificity of a test. This paper reviews this formula and provides examples evaluating the prevalence of HIV disease, the usefulness of ventilation-perfusion scans in diagnosing pulmonary embolism, and settings where screening tests should not be applied. These examples demonstrate that precise yet inexpensive estimates of disease prevalence are possible by enhancing the usefulness of an inaccurate test.

Bayes Theorem↗

PubMedDate not supplied

Group screening for cognition disorders in elderly persons.

Prevalence rates of cognitive impairment in persons aged 75 to 85 years are in the range of 10 to 19 percent, and 20 to 47 percent after the age of 85 years. Screening for dementia in persons aged 75 years and older would therefore identify a significant number of impaired persons. When screening for dementia, group testing would be more cost-effective than individual testing. We modified the Folstein Mini-Mental State examination (MMSE) for screening in a group setting. Community volunteers were tested at a geriatric health fair and at a special exercise class for the elderly. Subjects were subsequently tested individually using the standard Folstein MMSE. Analysis using Pearson correlation and a paired t-test indicates a high degree of concurrent validity between the two methods of administering the MMSE. This pilot study suggests that when screening elderly persons for dementia, a group-administered instrument can be a useful method to obtain a preliminary sample of cognitively impaired individuals.

Aged↗