"Ultrasensitive" silver stains: their use exemplified in the study of normal human cerebrospinal fluid proteins separated by two-dimensional electrophoresis.

We have developed a series of photochemical silver stains that are more than 100 times as sensitive as the Coomassie Blue stains. These stains facilitate the quantitative estimation of proteins in two-dimensional gel patterns. Recently, we discovered that by using light (photodevelopment) to catalyze the reduction of ionic silver to metallic silver, we could produce an image of proteins on polyacrylamide gels within 10 min after their electrophoretic separation. We used these stains to detect proteins resolved in two-dimensional electrophoretograms of lumbar cerebrospinal fluid from 51 normal human volunteers, finding no qualitative protein changes in the more than 300 CSF polypeptides resolved on each individual's electrophoretogram. We quantified 67 of these proteins per individual with computer-assisted densitometry, only five of which showed significant quantitative age-related alterations. We saw no sex-related differences. This consistency in the protein pattern for cerebrospinal fluid from normal individuals allows it to serve as a baseline for comparisons with disease states.