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Telltale Whiff of Illness

BOSTON--Breathalyzers already help police keep drunk drivers off the road. Now they may become a rapid and noninvasive way to diagnose diseases. A pair of scientists reported at the American Chemical Society meeting here today that they've developed a machine that in just minutes can detect trace compounds in the breath and diagnose diseases such as diabetes, kidney failure, ulcers, and possibly even cancer. Commercial versions of the instruments may be available within a few years.

To construct their breath analyzer, chemist David Smith of Keele University in Staffordshire, United Kingdom, and Patrik Spanel, a physicist with the Czech Republic's Academy of Sciences in Prague, brought a piece of space-spying technology down to Earth. Two decades ago, Smith and his Keele colleagues developed an instrument known as a selected ion flow tube (SIFT) to analyze the trace gases known to be present in interstellar gas clouds. The machine reacts ions with test samples and feeds these products into a mass spectrometer. The unique chemical signals for each trace compound are then compiled into a database.

For their current work, Smith and Spanel created a database for breath of healthy and sick humans. They carefully selected ions that react with volatile trace gases, but don't react with abundant compounds in breath such as oxygen and nitrogen. The technique is so sensitive that the researchers can distinguish dozens of compounds at concentrations of just parts per billion. While the original SIFT machines are bulky tabletop instruments, Smith says that in the last few months he and Spanel have developed a smaller, portable version and tested it with hospital patients.

When Smith and Spanel tested their instrument on patients with various disorders, the results were striking. Twenty patients with kidney failure, for example, showed levels of ammonia and acetone more than 10 times that of healthy controls, and the researchers could watch those levels fall back to normal as the patients received dialysis treatment. Smith also reported being able to track chemical markers of stress, diabetes, and ulcers, and they say preliminary data suggest they may even be able to use the technique to detect bladder and prostate cancer.

"These are very exciting results," says Michael Henchman, a chemist at Brandeis University in Waltham, Massachusetts. "David's technique could be as important to medicine as MRI [magnetic resonance imaging]."