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February 2010
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Chemists influence stem-cell development with geometry

University of Chicago scientists have successfully used geometrically patterned surfaces to influence the development of stem cells. The new approach is a departure from that of many stem-cell biologists, who focus instead on uncovering the role of proteins in controlling the fate of stem cells.

"The cells are seeing the same soluble proteins. In both cases it's the shape alone that's dictating whether they turn into fat or bone, and that hasn't been appreciated before," said Milan Mrksich, Professor in Chemistry and a Howard Hughes Medical Institute Investigator, who led the study. "That's exciting because stem-cell therapies are of enormous interest right now, and a significant effort is ongoing to identify the laboratory conditions that can take a stem cell and push it into a specific lineage."

The UChicago team found that making cells assume a star shape promotes a tense cytoskeleton, which provides structural support for cells, while a flower shape promotes a looser cytoskeleton. "On a flower shape you get the majority of cells turning to fat, and on a star shape you've got the majority of cells turning into bone," said Kris Kilian, a National Institutes of Health Fellow in Mrksich's research group. The UChicago team published its findings in the March 1 Early Edition of the Proceedings of the National Academy of Sciences.

Mrksich cautioned that the method is far from ready for use in the harvest of stem cells for therapeutic use, but it does signal a potentially promising direction for further study.

Mrksich's research group has a long history of developing methods for patterning surfaces with chemistry to control the positions, sizes and shapes of cells in culture, and applying those patterned cells to drug-discovery assays, and studies of cell migration and cell adhesion.

Contact: Steve Koppes

s-koppes@uchicago.edu

773-702-8366

University of Chicago

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Ultra-powerful Laser Makes Silicon Pump Liquid Uphill with No Added Energy

Researchers at the University of Rochester's Institute of Optics have discovered a way to make liquid flow vertically upward along a silicon surface, overcoming the pull of gravity, without pumps or other mechanical devices.

In a paper in the journal Optics Express, professor Chunlei Guo and his assistant Anatoliy Vorobyev demonstrate that by carving intricate patterns in silicon with extremely short, high-powered laser bursts, they can get liquid to climb to the top of a silicon chip like it was being sucked through a straw.

Unlike a straw, though, there is no outside pressure pushing the liquid up; it rises on its own accord. By creating nanometer-scale structures in silicon, Guo greatly increases the attraction that water molecules feel toward it. The attraction, or hydrophile, of the silicon becomes so great, in fact, that it overcomes the strong bond that water molecules feel for other water molecules.

Thus, instead of sticking to each other, the water molecules climb over one another for a chance to be next to the silicon. (This might seem like getting energy for free, but even though the water rises, thus gaining potential energy, the chemical bonds holding the water to the silicon require a lower energy than the ones holding the water molecules to other water molecules.) The water rushes up the surface at speeds of 3.5 cm per second.

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As universities tighten ethics policies, drug firms turn to private physicians to promote products

By John Fauber of the Journal Sentinel

Posted: March 14, 2010

This article is part of an ongoing series about how money and conflicts of interest affect medicine and patient care.

When looking for a doctor to travel the country and tout its costly prescription fish oil pill, GlaxoSmithKline didn't select a heavyweight university researcher.

Instead, it wrote checks to Tara Dall, a Delafield primary-care doctor who entered private practice in 2001.

For just three months of speaking engagements last year, GlaxoSmithKline paid Dall $45,000, ranking her among the most highly paid of more than 3,600 doctors nationwide who spoke for the company, which released records for only one quarter of the year.

The practice of doing promotional speaking for drug companies has come under fire in recent years.

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Exotic Antimatter Detected at Relativistic Heavy Ion Collider (RHIC)

Scientists report discovery of heaviest known antinucleus and first antinucleus containing an anti-strange quark, laying the first stake in a new frontier of physics

March 4, 2010

UPTON, NY — An international team of scientists studying high-energy collisions of gold ions at the Relativistic Heavy Ion Collider (RHIC), a 2.4-mile-circumference particle accelerator located at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, has published evidence of the most massive antinucleus discovered to date. The new antinucleus, discovered at RHIC’s STAR detector, is a negatively charged state of antimatter containing an antiproton, an antineutron, and an anti-Lambda particle. It is also the first antinucleus containing an anti-strange quark. The results will be published online by Science Express on March 4, 2010.

“This experimental discovery may have unprecedented consequences for our view of the world,” commented theoretical physicist Horst Stoecker, Vice President of the Helmholtz Association of German National Laboratories. “This antimatter pushes open the door to new dimensions in the nuclear chart — an idea that just a few years ago, would have been viewed as impossible.”

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