Stanford Bio-X researchers use needle-thin probe to get first look at working mu

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Stanford Bio-X researchers use needle-thin probe to get first look at

working muscle fiber

Microendoscope goes easy on patients, provides an alternative to

painful muscle biopsy

http://www.eurekalert.org/pub_releases/2008-07/su-sbr071008.php

Using an unusual microscope with a tip the size of a needle, Stanford

researchers are now able to look at tiny fibers of working muscles in

live humans, with minimum discomfort to the patient—a development

patients are sure to welcome.

This microendoscopy technique for viewing sarcomeres—microscopic

lengths of muscle fiber about 3 millionths of a meter long—has

advantages over the uncomfortable alternative, a muscle biopsy in

which a portion of the muscle is removed for examination.

Sarcomeres are the basic contracting engines of muscle. They

generally pull in a coordinated fashion, allowing us to walk down the

sidewalk or throw a sinking curveball from the pitcher's mound. But

out-of-sync sarcomeres are implicated in muscular dystrophy and other

diseases of diminished muscular control. It is thought that disease

may change the length of sarcomeres and cause havoc with muscle

control because the force exerted by muscle is critically dependent

on length.

To observe sarcomeres in action, researchers from Stanford's Bio-X

program have devised a needle-thin probe, which is inserted through

the skin into muscle. When a flash of finely tuned laser light is

sent through the probe, the sarcomeres respond with light of their

own to form a snapshot of muscle in action.

The researchers see the images in real time on a display screen. A

change in the depth of focus of the rapidly scanning device can

provide a three-dimensional movie.

" This is a method that does not require any operative procedures, "

said Mark Schnitzer, an assistant professor of biology and of applied

physics. For the first time, " it allows us to view individual

sarcomeres in live humans. "

The breakthrough was reported online in the journal Nature on July 6.

The technology could prove useful in understanding how muscles are

altered by spinal cord injuries or strokes as well as muscular

diseases, according to another of the researchers, Delp, a

professor of bioengineering and of mechanical engineering and, by

courtesy, of orthopedic surgery.

Other areas of interest include biomechanics, orthopedic

reconstructions, prosthetic devices and tendon transfers, in which

tension adjustments are a crucial element for patients relearning how

to walk or grasp. " If you measure the length of the sarcomeres during

surgery, then you can adjust them to work at their optimal length,

giving maximum muscle strength, " Delp said.