Drug effect on metabolism is measured by radioactive precursor uptake, thymidine, uridine (or uracil for bacteria), and amino acid, into DNA, RNA and proteins. Carbohydrate or lipid synthesis is similarly measured using suitable precursors. Turnover of nucleic acid or protein or the degradation of specific cell components, is measured by prelabeling (or pulse labeling) followed….

Northern blot analysis involves size separation of the RNA species by electrophoresis followed by identification with labeled gene-specific oligonucleotides or DNA probes. The size and abundance of the desired RNA is determined. The predominant rRNA in a total RNA preparation can also be detected by UV absorbance as a measure of intactness.

The RadioImmunoAssay (RIA) uses radiolabeled molecules to measure very low concentrations of substances. The format is usually a competition between the analyte being tested and a radiolabeled version of the same molecule. The method may use a typical ELISA plate or a precipitation method to separate bound from free analyte.

Use of radioisotopes offer extreme sensitivity for enzyme activity assays and detection of proteins, nucleic acids and other markers. We have licenses for 3H for labeled thymidine uptake into DNA, 32P for various nucleic acid assays, 14C and 35S for amino acid and protein studies, 45Ca for metabolism studies, 51Cr for target killing tests and….

Receptor function and quantitation is accomplished by binding its labeled ligand (growth factor, metabolic trigger, cancer drug, etc.) or other specific agents such as antibodies. Nonspecific binding is also measured and corrected specific binding is calculated. Some receptors are internalized and degraded following binding of their ligand and this can be measured. Activation of tyrosine….

Cell surface markers define cell subsets and state of activation. Most markers are receptors for agonists or regulators of cell function. The typical analytical method is flow cytometry.

The strength of antibody binding to its ligand is assessed by radioimmune assay (RIA), ELISA, or binding in a column support format. Dissociation is performed by increasing denaturating conditions, or by competition with a related ligand. The dissociation constant, Kd, is determined by a Scatchard plot.

A protein is characterized by binding to its receptor or ligand. The protein is bound to a solid support (ELISA plate, beads, column), incubated with labeled ligand, and the amount of bound ligand is determined. Equilibrium dialysis can be performed for precise Kd affinity values when applicable. Alternatively, the receptor may be on a cell….