Notes: The authors review the use of in vitro cytotoxicity testing in drug discovery to characterize the toxic potential of new chemical entities (nce) at the earliest stages of profiling. DOI: 10.2174/1875397300903010033 (4000)

Notes: The authors wanted to examine the role of plasma membrane protein Na+/H+ exchanger isoform 1 (NHE1) in apoptosis. API cells, a NHE1-deficient Chinese hamster ovary cell line, was cotransfected with wild-type NHE1 or mutant NHE1 constructs and destabilized yellow fluorescent protein (YFP). Cells were plated at a density of 1 × 10⁴ cells/well in a 96-well plate with or without FBS. To induce apoptosis in the cells, serum was withdrawn for 24 hours. The ratio of dead-to-live cells was measured using the MultiTox-Fluor Multiplex Cytotoxicity Assay. Cell death was also determined by examining the loss of YFP fluorescence under a microscope. (3937)

Notes: The authors of this paper describe an assay that uses protease biomarkers to assess cell viability and cell death simultaneously in a population of cells. The assay detects an ubiquitous protease activity that is associated with live cells and a second protease activity that is associated with cells that have lost membrane integrity. The readouts are either fluorescent or fluorescent and luminescent. The assay can be performed in multiplex with other assays, such as caspase assays, to gain additional information on the cell population, and it is amenable to high-throughput screening. (3927)