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February 2008
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April 2008

Researchers engineer new polymers to change their stiffness and strength when exposed to liquids

CLEVELAND -- An interdisciplinary team of researchers from the departments of macromolecular science and engineering and biomedical engineering at the Case School of Engineering and the Louis Stokes Cleveland Department of Veterans Affairs Medical Center has published ground-breaking work on a new type of polymer that displays chemoresponsive mechanic adaptability -- meaning the polymer can change from hard to soft plastic and vice versa in seconds when exposed to liquid -- in the March 7, 2008, issue of Science, one of the world's most prestigious scholarly journals covering all aspects of science.

Jeffrey R. Capadona, associate investigator at the VA's Advanced Platform Technology (APT) Center, graduate student Kadhiravan Shanmuganathan, and Case Western Reserve University professors and APT investigators Dustin Tyler (biomedical engineering), Stuart Rowan (macromolecular science) and Christoph Weder (macromolecular science) have unveiled a radically new approach for developing polymer nanocomposites which alter their mechanical properties when exposed to certain chemical stimuli.

"We can engineer these new polymers to change their mechanical properties -- in particular stiffness and strength -- in a programmed fashion when exposed to a specific chemical," says Weder, one of the senior authors of the paper.

"The materials on which we reported in Science were designed to change from a hard plastic -- think of a CD case -- to a soft rubber when brought in contact with water," adds Rowan, who has been Weder's partner on the project for almost six years.

"Our new materials were tailored to respond specifically to water and to exhibit minimal swelling, so they don't soak up water like a sponge," saud Shanmuganathan.

In their new approach, the team used a biomimetic approach -- or mimicking biology -- copying nature's design found in the skin of sea cucumbers.

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Engineered protein shows potential as a strep vaccine

A University of California, San Diego-led research team has demonstrated that immunization with a stabilized version of a protein found on Streptococcus bacteria can provide protection against Strep infections, which afflict more than 600 million people each year and kill 400,000.

In the March 7 issue of the journal Science, the researchers describe, for the first time, the detailed structure of the streptococcal M protein, which is critical to the virulence of Group A Streptococcus (GAS). GAS causes a wide variety of human diseases including strep throat, rheumatic fever, and the life-threatening “flesh-eating” syndrome called necrotizing fasciitis. Studies were performed using M1 protein, which represents the version of M protein present on the most common disease-associated GAS strains.

The team also produced a variant of M1 protein that stimulates the immune system in mice, without the serious side effects caused by natural M1 protein. They say that their results should help scientists develop M1 protein-based vaccines against GAS.

“Using X-ray crystallography, we determined that M1 protein has an irregular, unstable structure,” explained Partho Ghosh, a professor of chemistry and biochemistry in UCSD’s Division of Physical Sciences. “We created a modified version of M1 with a more stable structure, and found that it is just as effective at eliciting an immune reaction, but safer than the original version of M1, which has serious drawbacks to its use in a vaccine.”

“Certain antibodies that are produced by the immune system against M1 protein have been shown to cross-react with normal human tissues including heart muscle, potentially triggering the serious autoimmune disease known as rheumatic fever,” added Victor Nizet, professor of pediatrics and pharmacy at the UCSD School of Medicine and the Skaggs School of Pharmacy and Pharmaceutical Sciences. “M1 protein can also act as a toxin, producing clotting abnormalities and lung injury when injected into mice. Therefore our results with modified M1 provide very novel insight about the role of M proteins in invasive GAS disease and rheumatic heart disease.”

Because M protein is vital for the survival of GAS in the host, various research groups have been trying to determine its structure for decades. According to Ghosh, M1 is “long and skinny,” which makes it a particularly difficult protein to crystallize. Case McNamara, who solved the protein structure while he was a graduate student working with Ghosh and is the first author on the paper, spent three years optimizing the conditions to crystallize the protein and collect the required data.

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UW tries worm eggs to help MS patients

Doctors to study immune systems

By JOHN FAUBER
jfauber@journalsentinel.com
Posted: March 6, 2008

For several years, scientists have suspected that our hyper-hygienic world of vaccinations, antibacterial soap and bottled water actually might be making some people sick by bewildering their immune systems and causing them to turn on their bodies.

Now, doctors at the University of Wisconsin-Madison are about to carry that theory to the ickiest extreme.

They soon will begin serving up liquid concoctions of microscopic worm eggs to people with multiple sclerosis in the hope that the parasites will tone down the immune systems of the patients and relieve their symptoms.

The experiment is based in part on observations first made more than 40 years ago that high levels of sanitation in a child's environment are associated with an increased risk of developing MS.

MS is believed to be a so-called autoimmune disease in which the body's immune system launches an attack against its own tissue, specifically the substance myelin, which insulates nerve cells.

Some researchers say the trick to halting the attack might lie in the tiny helminth whipworm, an organism that long has infected humans, usually without harm, especially in undeveloped countries.

UW doctors plan to give helminth eggs to five MS patients over the course of several months. If the experiment proves safe and shows promise, more patients will be enrolled.

More than 2,000 of the football-shaped eggs, which are produced by the German company OvaMed, can fit onto a space that's smaller than the head of a pin.

Once inside the body, the eggs will hatch and the worms grow to about the size of an eyelash. It is hoped that the presence of the worms will redirect the immune systems of the patients and slow down the damage to the myelin coating on their nerve cells.

Full story.

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