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A magnetic force of medical research

His face set in stony concentration, Swiss engineer Karoly Molnar moved quickly between his monitors and the frosty, 13-foot creation that he was bringing to life in a basement at the University of Maryland School of Medicine in Baltimore.

As Molnar carefully injected electric current and balanced it with hundreds of gallons of cooling liquid helium, one of the most powerful superconducting magnets ever built for medical research slowly powered up last week.

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This fall, David J. Weber expects the magnet - at the core of the school's new 800 megahertz nuclear magnetic resonance (NMR) spectrometer - will be ready to help him and other scientists decipher the structure of critical human proteins, and aid in the design of new disease-fighting drugs.

Weber is an associate professor of biochemistry and molecular biology at the medical school and is director of the Nuclear Magnetic Resonance Imaging Center, where the new, $2.5 million spectrometer is being installed.

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While there are perhaps two dozen such 800 megahertz NMR spectrometers in the world, and more on the way, Weber said, magnetic shielding and other features on UM's device make it "one of the most sensitive instruments in the world for medical research."

The federal government paid half the costs for the project and the state and the school of medicine covered the rest.

"Our job is to see what proteins look like and how they fit together," Weber said.

The process is done by lowering 11-drop samples of the proteins into the middle of a powerful magnetic field. Scientists then zap the samples with microwave energy at 800 megahertz to excite the proteins' atoms. Measuring their response with a deeply chilled electronic instrument called a cryoprobe,they can identify each of the molecules' chemical constituents, and "get a high-resolution, atomic-level picture of what the protein looks like," Weber said.

The pictures reveal how the proteins move and flex in three-dimensional space and how they latch on to both natural substances and pharmaceuticals. And that can lead to cures.

Working with the school's less-sensitive eight-year-old NMR spectrometer, Weber has been investigating a tumor protein that appears to stimulate the growth of skin cancer.

By imaging the shape of the suspect protein's molecule, he has been able to match it to a drug whose molecule is nicely shaped to gum it up.

"We're crossing our fingers it will work in humans," he said. "I've never been so excited in my life."

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Running around the clock, the powerful new machine Molnar is installing will offer Weber and other scientists higher resolution images of the proteins they're studying and quicker results than are possible now.

But it's an ally that must be handled with care.

The 8-ton magnet at the heart of the new spectrometer is housed in a specially designed room beneath the medical school's new $78 million Health Sciences Facility II on Penn Street.

A sign on a door hints at the power inside: "Extreme Caution! Strong Magnetic Field."

Built by the Swiss firm, Bruker BioSpin AG, the magnet rests inside a 13-foot-tall "dewar" - a giant gray thermos bottle designed to keep it cold.

The magnet's precise structure is a Bruker trade secret, but it is powered by electricity flowing through coils of wire made of a metal alloy that is "superconductive."

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Superconductivity means that once the magnet's wires are electrically energized and cooled by the liquid helium to 4 degrees Kelvin -minus 269 degrees Celsius - Weber can unplug it.

The electric current will continue to flow without resistance, keeping the magnet energized without additional power.

"We feed it helium; that's my major expense," Weber said. It will need less than 33 frigid liters a week, on average, at $3 a liter.

If everything goes well, he said, it won't have to be re-energized for 15 or 20 years.

The power of the machine's magnetic field is rated at 18.1 tesla. That's 12 times the strength of the magnetic resonance imaging (MRI) machines used to diagnose patients' illnesses.


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