At Stanford University, a research group has developed a method, called fluorescence microendoscopy, to take a peek at what’s going on inside the muscles of living, breathing creatures, like mice and humans. The research may allow for greater understanding of how muscle tissue adapts to environmental strain and in response to disease. Furthermore, this technology one day might become a diagnostic modality.

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, Scott 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.

Press release: Stanford researchers take first look at working muscle fiber
Abstract in Nature: Minimally invasive high-speed imaging of sarcomere contractile dynamics in mice and humans doi:10.1038/nature07104

At the National Institute of Standards and Technology scientists are using a technique called “phage display” to track the formation of hydroxyapatite, a calcium phosphate compound that makes up teeth and bones.

Although they have somewhat different mechanical properties, the major structural component of both teeth and bones is a crystalline compound of calcium phosphate called hydroxyapatite. Subtle variations in the way the crystal forms account for the differences. Identifying and monitoring the formation of this particular crystal is of paramount importance to biomedical researchers working on a variety of problems including the remineralization of teeth to repair decay damage, the integration of prosthetic joints and tissue-engineered bone materials for joint and bone replacement, and cell-based therapies to regrow bone tissue.
To date, however, there is no specific, practical method to spot the formation of hydroxyapatite in living systems or tissue samples. Materials scientists can identify the crystal structure with high reliability by the pattern it makes scattering X rays, but it’s a complex procedure, requires fairly pure samples and certainly can’t be used on living systems. There are some widely used chemical assays—the von Kossa assay, for example—but these also are destructive tests, and more importantly they really test simply for the presence of the elements calcium or phosphorus. They can’t distinguish, for example, between deposits of amorphous calcium phosphate—a precursor—and the hydroxyapatite crystal.
To find a more specific, less destructive probe, the NIST team used a relatively new technique called “phage display” that can rapidly create and screen huge numbers of biomolecules for specific interactions. Phages are a primitive and ubiquitous class of viruses that infect bacteria. Some simple phages can be genetically modified to randomly assemble short sequences of amino acids—small proteins called peptides—on their outer shells as binding sites. An engineered population of phages will synthesize billions of random peptides. If these phages are exposed to the target surface—hydroxyapatite crystal in this case—and then washed off, those left behind are the ones that tend to stick. Cloning the survivors and repeating in several cycles with increasingly stringent conditions eventually isolates a handful of candidate peptides that can be further tested to measure their affinity for the target.
As reported in a recent paper, the NIST team used the technique to identify a new peptide that relies both on the chemical composition and the crystal structure of hydroxyapatite to bind to the mineral’s surface. The peptide’s ability to “recognize” the specific structure of hydroxapatite, say the researchers, could be exploited as a nondestructive tag to monitor the progress of bone and tooth mineralization for diagnostic and therapeutic applications.

Press release: Toothpick: New Molecular Tag IDs Bone and Tooth Minerals
Image: Deposits of hydroxyapatite crystal (l.) and the same mineral in a cross section of a human tooth (r.) light up bright green where they’ve been tagged with a new peptide created at NIST to bond specifically to the compound. The peptide has been linked to a fluorescent stain for imaging. NIST

Yale scientists have been working on a new method to screen IVF embryos for viability.
From the BBC:

The ViaTestE device, developed by scientists from Yale, can score the metabolic activity of a sample of the fluid from around the embryo using spectrophotometry, which uses infrared light to measure the make-up of a substance.
For example, it is used to tell if milk is full-fat or semi-skimmed.
In this instance, the technology checks the activity of metabolites – the substances produced by the embryo.
The team tested around 500 samples of embryo fluid, without knowing which had implanted successfully.
The embryos had also been assessed in the clinics using the traditional method.
That gave around a 40% rate of accurately identifying the embryos which developed into viable foetuses.
But “fingerprinting” using the new test increased that rate to between 60% and 70%.
From these and other results, the scientists believe using the test could improve pregnancy rates by between 10-15%.

More at the BBC News…
Image credit: Wellcome images: Colour-enhanced scanning electron micrograph of a human embryo at day 5 sitting on the tip of a pin….