Radioimmunoassay (RIA) is a very sensitive in vitro assay technique used to measure concentrations of antigens (for example, hormone levels in blood) by use of antibodies. As such, it can be seen as the inverse of a radiobinding assay, which quantifies an antibody by use of corresponding antigens. Although the RIA technique is extremely sensitive and extremely specific, requiring specialized equipment, it remains among the least expensive methods to perform such measurements.
Everything American Express is offering during the US Open this year is designed to enhance what tennis fans love about this tournament, said Deborah Curtis, vice president of entertainment and sports marketing at American Express.
It's hard to get over a big divorce. Just ask American Express (NYSE:AXP), which is the exclusive credit card brand accepted at Costco Wholesale (NASDAQ:COST) stores in addition to being the popular retailer's sole co-branded partner for its TrueEarnings credit card.But not for much longer.ess than a month after the split with AmEx was announced, the retailer drafted Visa (NYSE:V) to be its exclusive credit card brand, and Citigroup (NYSE:C) as the co-brander of its proprietary card. The new deals will come into force at the beginning of next April, just after the AmEx arrangement expires.