Biomedical subjects
D Greeley
Publications and source records attributed to D Greeley.
Biochemical analysis of the transducin-phosphodiesterase interaction.
In vertebrate rod cells, the activated alpha-subunit of rod transducin interacts with the gamma (regulatory) subunits of phosphodiesterase to disinhibit the catalytic subunits. A 22-amino acid long region of rod transducin involved in phosphodiesterase activation has recently been identified. We have used peptides from this region of rod transducin and from several other G protein alpha-subunits to study the nature and specificity of the G protein alpha-effector interaction. Although peptides derived from rod transducin, cone transducin and gustducin are similar, only the rod peptide is capable of activating rod phosphodiesterase. Using substituted peptides we have identified five residues on one exposed face of rod transducin as important to phosphodiesterase activation. These results disagree with previous models which propose that loop regions of rod transducin interact with phosphodiesterase gamma.
Estimation of the mean caliper diameter of cell nuclei. I. Serial section reconstriction method and endothelial nuclei from human lung.
In morphometric studies of lung tissue, accurate determination of the total number of any specific type of cell, such as the endothelial cell, requires knowledge of the shape of the cell nucleus. This knowledge of shape is necessary to calculate the mean caliper diameter, which, in turn, is an indispensible element of the equation for the number of nuclei (therefore cells) per unit volume (NV). Nine human hung endothelial cell nuclei were therfore reconstructed in dental wax from serial sections and were found to be pleomorphic triaxial ellipsoids. Five of these approached an oblate shape. The axes of these nine nuclear models were directly measured and a computer program using numerical integration was written to determine the mean caliper diameters of these ellipsoids. The estimated mean semi-axes of the nine nuclei were (+/-SD) 5.98+/-1.61, 3.61+/-0.70, 1.36+/-0.34; and the estimated overall mean caliper diameter for the total population of human lung endothelial nuclei was 7.97+/-1.27 micrometers.
Laboratory findings in pulmonary embolism.
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