Science: Radiation exposure, even at life-threatening levels, can be hard to detect until a patient becomes symptomatic. Several studies have shown that an analysis of the microRNA that circulates in blood can reveal whether a person has been exposed to radiation. Now Dipanjan Chowdhury of Harvard Medical School and his colleagues have used microRNA to determine the level of exposure and predict survival. They exposed mice to a range of radiation levels, from mild to lethal, and compared microRNA analysis from the next day with blood and bone marrow samples taken at four later times. Out of 170 microRNAs identified, the concentrations of 5 of them varied markedly depending on the amount of radiation the mice received. From those concentrations, Chowdhury's group could determine how much radiation was received well before the bone marrow samples showed damage.
