Maga Barzallo Sockemtickem, 16, received a bone-marrow transplant at Seattle Children's Hospital in 2011 for leukemia and returned in July 2012 for follow-up treatment. On July 25, an artist at the hospital set up a cat photo installation in her room. Courtesy of Seattle Children's Hospital hide caption

itoggle caption Courtesy of Seattle Children's Hospital

Scientists say energy-saving compact fluorescent (left) or light-emitting diode (right) light bulbs can have unsavory health effects. PRNewsFoto/OSRAM SYLVANIA hide caption

itoggle caption PRNewsFoto/OSRAM SYLVANIA

The white arrows in these two tumor samples point to a subset of tumor cells that are in a resting state. Nature hide caption

itoggle caption Nature

Timothy Ray Brown, shown in May 2011 with his dog Jack in San Francisco, is the only man ever known to have been fully cured from AIDS. Brown is known as the "Berlin patient" because he had a bone marrow transplant in a German hospital five years ago. Eric Risberg/AP hide caption

itoggle caption Eric Risberg/AP

Starting a bone marrow registry in Nigeria "became an obsession" for Seun Adebiyi. "I thought that even if I couldn't find a match, I wanted to make it easier for other black patients to find a match." Seun Adebiyi hide caption

itoggle caption Seun Adebiyi

Child life specialist Kelly Schraf helps to put at ease Yoselyn Gaitan, 8, who had surgery on her cleft palate, at Children's National Medical Center in Washington, D.C. Jenny Gold for NPR hide caption

itoggle caption Jenny Gold for NPR

Which one of these sunscreens would be considered safe and correctly labeled by the Food and Drug Administration? Not a single one. Safe sunscreens are SPF15 or higher, and the new rules require those with broad-spectrum protection to include the term next to and in the same style as the sun protection factor. Benjamin Morris/NPR hide caption

itoggle caption Benjamin Morris/NPR

An American Cancer Society Relay for Life event at the University of Texas-Dallas in 2006. The events are meant to "celebrate the lives of people who have battled cancer, remember loved ones lost, and fight back against the disease," according to the organization. Josh Berglund/via Wikimedia Commons hide caption

itoggle caption Josh Berglund/via Wikimedia Commons

A woman pours two tablets into her hand from a pill bottle. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Isabel Doran, 4, gets a CT scan at Children's National Medical Center with her mom, Veronica Doran. The X-ray radiation in CT scans raises the risks for cancer, including leukemia, a new study shows. Dayna Smith/The Washington Post/Getty Images hide caption

itoggle caption Dayna Smith/The Washington Post/Getty Images

Before the colonoscopy begins, it pays to ask your doctor some pointed questions. Sebastian Schroeder/iStockphoto.com hide caption

itoggle caption Sebastian Schroeder/iStockphoto.com