Oxford University researchers say they've developed a blood test that could be used to measure stress, potentially as a hand-held device. Pending further research, the diagnostic could help screen people that need treatment for stress, which can lead to heart disease or other health problems. As the Daily Mail reports, the U.K. team pursued a simple approach in which clinicians add a chemical to a drop of blood that makes white blood cells react as they would to a perceived danger, such as when exposed to bacteria. A weak response would indicate the individual is already stressed, the story explains. Story