Biomedical subjects

M R Linschoten

Publications and source records attributed to M R Linschoten.

4 recordsLinked to original sources

PubMed2001

Fast and accurate measurement of taste and smell thresholds using a maximum-likelihood adaptive staircase procedure.

This paper evaluates the use of a maximum-likelihood adaptive staircase psychophysical procedure (ML-PEST), originally developed in vision and audition, for measuring detection thresholds in gustation and olfaction. The basis for the psychophysical measurement of thresholds with the ML-PEST procedure is developed. Then, two experiments and four simulations are reported. In the first experiment, ML-PEST was compared with the Wetherill and Levitt up-down staircase method and with the Cain ascending method of limits in the measurement of butyl alcohol thresholds. The four Monte Carlo simulations compared the three psychophysical procedures. In the second experiment, the test-retest reliability of MLPEST for measuring NaCl and butyl alcohol thresholds was assessed. The results indicate that the ML-PEST method gives reliable and precise threshold measurements. Its ability to detect malingerers shows considerable promise. It is recommended for use in clinical testing.

Adolescent↗

PubMed1994

Ipsi- and bilateral interactions in taste.

In two experiments, the integration over spatial extent in taste was investigated for threshold sensitivity to NaCl and for suprathreshold intensity perception of saltiness. The area of stimulation was doubled by adding either an ipsilateral or a bilateral stimulus. The two stimuli could be of equal or unequal intensity. The data showed that at threshold level a probability summation model applied to all bilateral and most of the ipsilateral stimulus combinations. Probability summation failed to predict detection probability when two stimuli with different intensities were presented at the same tongue side. For suprathreshold stimuli, the magnitude of the saltiness sensation as estimated by a line-length method depended on the level of stimulation. The possible peripheral interaction mechanisms and central factors contributing to the taste response were discussed.

Adult↗

PubMed1986

Mapping the turkey erythrocyte beta receptor: a distance geometry approach.

Extensions and refinements of the receptor mapping method as originally developed by Crippen are presented. In a set of newly developed algorithms measures are taken to reduce the number of required energy parameters to a statistically acceptable degree. The most important measure is the incorporation of lipophilicity as a hydrophobic bonding parameter to describe the binding of parts of the ligands to lipophilic areas on the receptor. In order to test the applicability of our set of programs, we mapped the turkey erythrocyte beta receptor using a data set of Bilezikian. It was found that the experimentally determined free energies of binding can be reasonably described using a nine-point geometrical representation of the receptor site and only six energy parameters. The deduced model predicts that the phenyl rings of phenylethanolamines and phenoxypropanolamines occupy different parts of the receptor site.

Animals↗

PubMed1985

Quantitative evaluation of the beta 2-adrenoceptor affinity of phenoxypropanolamines and phenylethanolamines.

The influence of the aromatic moiety of beta-adrenoceptor ligands on the affinity for the beta 2-adrenoceptor has been studied. Three classes of ligands have been examined, viz. N-isopropyl- and N-tert-butylphenylethanolamines and N-isopropylphenoxypropanolamines. Computer-assisted analysis of the inhibition by any of these ligands of the specific (-)-[3H]dihydroalprenolol binding to the beta 2-adrenoceptors of a bovine skeletal muscle preparation in the presence of GppNHp (10(-4) M) yielded the affinities of these ligands at pH 7.5. The obtained values were adjusted for the amounts of cations present at this pH value. A significant correlation was found between the calculated lipophilicities and the experimentally determined affinities in the three classes. Furthermore, steric factors seem to play an important role, as these correlations were improved by the introduction of steric parameters for the aromatic substituents in the regression analyses. From the established equations it is concluded that the phenoxypropanolamine derivatives bind to the beta 2-adrenoceptor in a way different from that of the ligands in both ethanolamine classes.

Animals↗