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The Laboratory
in the News

New way to fight cancer revealed
Researchers from the Laboratory and the University of California at Davis Cancer Center have unveiled a reliable technique to characterize the binding interaction of multivalent molecules designed for targeted drug delivery in cancer treatment. The team used atomic force microscopy to measure the binding forces between several single-chain antibody fragments and Mucin1 peptide. Large quantities of Mucin1 are commonly found in a variety of human epithelial cells, and one of its forms is a characteristic marker for prostate, breast, colon, lung, gastric, and pancreatic cancers. Binding between antibodies that recognize the marker and Mucin1 is critical to targeted drug delivery for cancer patients.
Not only does the technique aid doctors in treating cancer, but it also may benefit the Laboratory’s efforts in evaluating antibodies and designing better binding molecules for biosensors that have a critical role in national security. The team’s research appeared in the November 15, 2005, edition of the Proceedings of the National Academy of Sciences.
Contact: Todd A. Sulchek (925) 422-2796 (sulchek1@llnl.gov).

Model shows stars form by gravitational collapse
Researchers from the Laboratory, the University of California at Berkeley, and Princeton University have concluded that the generally accepted competitive accretion model of star formation cannot explain what astronomers observe of star-forming regions studied to date. Their findings appeared in the November 17, 2005, edition of Nature. Through a series of theoretical calculations and supercomputer simulations, the team determined that new stars form by gravitational collapse rather than the widely held belief that they come from the buildup of unbound gas.
The model used by the team simulates the complicated dynamics of gas inside a swirling, turbulent cloud of molecular hydrogen as it accretes onto a star. This study is the first to determine the effects of turbulence on the rate at which a star accretes matter as it moves through a gas cloud. In the competitive accretion model, clumps in hydrogen gas clouds form into cores. These cores are the seeds that grow to become stars. The researchers’ model, often termed the gravitational collapse and fragmentation theory, also presumes that clouds develop clumps in which protostellar cores form. However, the cores are large and, although they may fragment into smaller pieces to form binary or multiple star systems, contain nearly all the mass they ever will. The work was supported by the National Aeronautics and Space Administration, the National Science Foundation, and the Department of Energy.
Contact: Richard Klein (925) 422-3548 (rklein@llnl.gov).

Protein folding may lend clue to risk factor genes
Ted Laurence of the Laboratory’s Physical and Biosciences Institute, along with collaborators from the University of California at Los Angeles, measured varying distances within single protein molecules to understand the process of protein folding. The recent study sheds some light on what causes a protein to go from a folded to unfolded state. Protein folding gone awry may be a key factor in determining why certain people are prone to Alzheimer’s and other neurodegenerative diseases. In addition, understanding how and why a protein folds can help scientists design proteins to perform specific tasks.
Using a technique called fluorescence resonance energy transfer, the team measured distances between two specific points on a protein. Special fluorescent chemical groups—a donor and an acceptor—are attached to those points. If the donor and acceptor are within 8 to 10 nanometers apart, the energy transfer occurs. “The structure of the energy landscape is what encourages the protein to fold or not to fold,” says Laurence. “We want to see what a protein is doing in an unfolded state and why it folds. Then we can understand why the folding sometimes goes wrong.” The team’s research appears in the November 29, 2005, edition of the Proceedings of the National Academy of Sciences.
Contact: Ted Laurence (925) 422-1788 (laurence2@llnl.gov).

Scientists get precise measure of a basic theory
Laboratory researchers have made a new measurement that is 10 times more precise than recent measurements to test quantum electrodynamics (QED)—an extension of quantum mechanics. The scientists entered a new realm in the search for QED deviations by measuring light generated in the extreme electric fields surrounding the nucleus of uranium. Deviations would have far-reaching consequences for understanding the universe because it would indicate that QED is not a fundamental theory of nature.
The team tested the theory using Livermore’s SuperEBIT, an electron-beam ion trap, to strip uranium of all but three electrons, forming a uranium plasma. Using high-resolution spectrometers in the experiments, the researchers were the first to look directly at the light emitted by the uranium plasma. The high precision of the SuperEBIT measurements allowed the team to extract an experimental value for the new QED effects, in which the polarized vacuum and the self-energy interacted with each other and themselves. Previous measurements only tested the noninteracting manifestations of QED. The team’s results appeared in the December 2, 2005, edition of Physical Review Letters.
Contact: Peter Beiersdorfer (925) 423-3985 (beiersdorfer@llnl.gov).

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UCRL-52000-06-3 | March 1, 2006