IMAGING

For a muscle to lift a heavy object, tiny components of muscle fiber, called sarcomeres, work together to generate force. The elegant way sarcomeres are arranged and oriented affects the way muscles move - so problems in sarcomere coordination can lead to diseases, such as muscular dystrophy. It's been challenging to visualize sarcomeres at work in living humans - until now. Researchers led by Mark J. Schnitzer and Scott Delp of Stanford University developed a technique in which they insert a needle-shaped microscope with a diameter of less than half a millimeter into the muscle. They then flash a laser of a particular color at the muscle fibers, and based upon the orientation of sarcomeres, the muscle flashes a light of a different color back into the scope. These light reflection patterns allow researchers for the first time to visualize the way many individual sarcomeres work together in living humans. "We hope that someday this might be a tool for the management of neuromuscular diseases, as well as for guiding motor rehabilitation such as in cases of stroke or spinal cord injury," Schnitzer said. BOTTOM LINE: For the first time, a tiny microscope allows scientists to see inside human muscle fibers, a tool that may one day help to diagnose and manage muscle diseases. CAUTIONS: The technique is somewhat limited by a small field of view - meaning it can only survey a part of the muscle at a time. WHAT'S NEXT: "We're planning on using this technique to look at how sarcomeres behave in human neuromuscular disorders," Schnitzer said. WHERE TO FIND IT: Nature, July 7.

SUSHRUT JANGI