[Receptor binding oscillations]. / Kolebaniia retseptornogo sviazyvaniia.

A kinetic analysis of the delta-opiate receptor agonist, [3H] DADLE, binding to cell (NG108-15) suspensions has led to the discovery of a new periodic biological phenomenon, namely, receptor activity oscillations. The absence of oscillations for the antagonist binding to the receptors suggests that oscillations are generated only as a result of receptor signal transformation. The correlation between the quantitative characteristics of the kinetic curves and the experimental conditions points to the fact that receptor binding oscillations may be due either to the receptor binding to the G-protein or the interaction of the receptor (or G-protein) with microtubules.

A statistical model and computer program to estimate association constants for the binding of fluorescent-labelled monoclonal antibodies to cell surface antigens and to interpret shifts in flow cytometry data resulting from alterations in gene expression.

Flow cytometry is used to obtain estimates for the distribution of fluorescent ligands bound to cell surface receptors throughout a cell sample. The equipment used provides light scattering parameters and also cell staining data in the form of dot plots and histograms of fluorescence intensities and the frequency of occurrence of particular fluorescence intensities. It is then assumed that fluorescence intensity is proportional to the number of labelled ligands bound to surface receptors. In this paper we present an outline of a statistical theory to account for the stretching and translation of such flow cytometry profiles which occur either as a result of alterations in gene expression, or from changing the sub-saturating concentration of fluorescent-labelled monoclonal antibodies or lectins used to stain the cells. We describe how the theory has been incorporated into two programs CSAFIT (cell surface antigen fit) and MAKCSA (make data to test CSAFIT). The program CSAFIT can be used to estimate two parameters, alpha and beta, by constrained non-linear regression analysis of the flow cytometry profiles. If the shift results from changes in the concentration of a staining agent then the estimates alpha and beta calculated by CSAFIT are functions of the ligand concentration, the ligand type and the cell line characteristics. They quantify the stretch and translation events that are encountered in flow cytometry. So when the parameter estimates alpha and beta are then further analysed as functions of ligand concentration, estimates for the average association constant K for the binding-site/ligand interaction can be obtained. This paper describes details of the development of programs CSAFIT and MAKCSA. We also discuss the distribution of parameter estimates calculated by CSAFIT and the overall performance of CSAFIT as assessed by simulation studies using data generated by MAKCSA.

Receptor binding on whole cells can oscillate.

The study of the kinetics of binding of the opiate receptor agonist [3H]DADLE with NG108-15 cell suspensions has revealed a new periodic biological phenomenon, i.e., oscillations of the cellular receptor activity. The absence of oscillations for binding of the receptor antagonist shows that oscillations occur as a result of the transformation of the receptor signal only.

[Theoretical examination of kinetic regularities in interaction of second messenger systems upon activation of cells by an external chemical signal]. / Teoreticheskoe rassmotrenie kinetitcheskikh zakonomernoste'i protsessov vzaimodeistviia sistem vtorichnykh messendzherov pri aktivatsii kletki vneshnim khimicheskim signalom.

A model of cell activation under the action of an external chemical signal is examined. The model is based on the assumption of simultaneous stimulation of, as a minimum, two different systems of second messengers interacting with each other. The kinetics of intracellular response may be principally different in character depending on the relation of model parameters. Ligand specificity manifests itself either in qualitative changes in the behavior of the system under the action of different ligands of the same class or in changes in the efficiency of intracellular response. In terms of these notions an interpretation of experimental data on cytoplasmic Ca2+ concentration oscillations in individual cells is presented. Methods for experimental verification of the model are considered.

Analysis of ligand-receptor binding by the difference method.

A new method has been proposed for analysis of experimental data on ligand-receptor binding at equilibrium. This method makes it possible to detect heterogeneity of a receptor system in cases where the contribution of the high-affinity site to total binding is rather small and the problem of graphic discrimination of a model cannot be solved unambiguously by other methods. The difference method permits us to exclude experiments on measuring nonspecific binding. A computer program for analysis of ligand-receptor binding has been worked out in which the difference method and traditional methods of binding isotherm analysis are realized. Numerical modeling has shown that the best strategy in experimental data processing is the treatment of total binding isotherms by both the difference method and regression analysis, including the nonspecific binding constant as one of the regression parameters.