Sequencing the genes of a cancer cell turns up lots of genetic mutations — but some of them are harmless. The goal is to figure out which mutations are the troublemakers. Kevin Curtis/Science Source hide caption

itoggle caption Kevin Curtis/Science Source

Truvada can dramatically reduce the risk of HIV infection when taken as a preventative medicine — if taken every day. Studies are underway to determine if young people are likely to take the pill consistently. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images
Cargo/ImageZoo/Corbis

Scientists reprogrammed the common bacterium E. coli so it requires a synthetic amino acid to live. BSIP/UIG via Getty Images hide caption

itoggle caption BSIP/UIG via Getty Images

Jackie Fortin's daughter, Cassandra, last summer. Courtesy of Jackie Fortin hide caption

itoggle caption Courtesy of Jackie Fortin

Radiation therapy is effective in treating breast cancer but typically requires dozens of visits over five to seven weeks. A newer protocol takes just three weeks. Antonia Reeve/Science Source hide caption

itoggle caption Antonia Reeve/Science Source

Bob Smithson, 79, can now hold his head upright and breathe on his own, thanks to a medication for myasthenia gravis. M. Scott Brauer for NPR hide caption

itoggle caption M. Scott Brauer for NPR

Life online is all about sharing images. Being able to share medical images would make health care a lot easier, patients say. Science Photo Library/Corbis hide caption

itoggle caption Science Photo Library/Corbis
Maria Fabrizio for NPR