Application of the miniature ultracentrifuge in receptor-binding assays.

A new binding assay for membrane receptor systems has been developed employing an air-driven ultracentrifuge (Beckman Airfuge). The main advantages of this method for measurement of radioligand binding in aqueous medium are (i) the rapidity (30 s) in separating the bound from the unbound fraction, (ii) the small volume (100 μl) of assay medium which permits a relatively small excess of ligand over receptor to be employed, and (iii) the simplicity of manipulations which allows a high degree of replication. The variation in a triplicate set of assays is usually less than 0.5%. By virtue of maintaining equilibrium throughout the assay the present method is especially useful for ligands exhibiting rapid reversibility in binding. Binding of [³H]ouabain to several membrane (Na⁺, K⁺)-ATPases and binding of [³H]etorphine to the oplate receptor from brain membranes are discussed here. Also the inhibition of [³H]ouabain binding by Tris is discussed.     

Ventilation or dignified death for patients with high tetraplegia.

The case histories of the 37 patients of the Mersey Regional Spinal Injuries Centre who were artificially ventilated between 1968 and 1984 were reviewed. The patients and caring relatives were interviewed separately to determine their views. Of 21 patients who were still alive, 18 said that they would wish to be temporarily ventilated again if the need arose, two were undecided, and one said that she would wish to be allowed to die. Sixteen caring relatives said that they were glad that the decision to ventilate had been taken. Those who were not glad were all young mothers. The outcome from any combination of factors that existed before injury could not be predicted except that most patients over age 59 fared badly. Patients with spinal cord damage should be artificially ventilated if required, provided that this can be carried out well and that total emotional, educational, and physical support can be provided and maintained. Whether or not scarce resources should be deployed in this manner requires discussion.