background and objectives: numerous procedures in biology and medicine require the counting of cells. direct enumer- ation of colony forming units (cfus) is time-consuming and dreary accurate cell counting on plates with high numbers of cfus is error prone. in this study we report a new indirect cell counting method that was developed based on the use of redsafe fluorometric assay. the usefulne...

An assay of serum digoxin and other cardiac glycosides by displacement of 3Houabain from Na-K ATPase is described. It is rapidly set up by any laboratory with a liquid scintillation counter. It can also assay digitalis leaf, digitoxin, and gitalin (Gitaligin), and has uncovered unsuspected administration of them. The assay takes less than 1 hour. No quench correction of counts is required. One ...

We describe here a simple assay that allows the visual detection of a protease. The method takes advantage of the high molar absorptivity of the plasmon band of gold colloids and is based on the color change of their solution when treated with dithiols. We used C- and N-terminal cysteinyl derivatives of a peptide substrate exploiting its selective recognition and cleavage by a specific protease...

ES cells. This phenomenon has been observed in our laboratory in a number of cases. Clones putatively identified as homologous recombinants by Southern analysis can be quickly checked for random insertion of extra copies of the targeting vector by PCR. Given the small difference in size between the two alleles and use of only two primers common to both WT and mutant DNA, the amplification rate ...