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Science/Tech See other Science/Tech Articles Title: CU laser device analyzes breath to detect disease By Katy Human The Greek doctor Hippocrates sniffed the breath of his patients for clues about their health — 2,400 years ago. Now, Boulder physicists have developed a more precise way to study the air we exhale, they reported Monday. Their new laser-based technique could someday be used to diagnose cancer before it spreads, catch an ulcer before it deepens or identify early diabetes, said Jun Ye and Mike Thorpe at the University of Colorado at Boulder. By blasting breath samples with laser light, the scientists could cheaply and simultaneously measure dozens of chemicals, they said. "We really hope this is a technique that will have a huge impact in medical science," Ye said. "Health costs are so high, and if we can do a lot of preventive medicine before people get into later stages of disease, it would help." Other medical researchers are searching for accurate ways to analyze breath for similar reasons, said Terence Risby, an adjunct professor at the Johns Hopkins Medical Institutions in Maryland. Risby has worked on breath analysis for years and helped develop devices that can detect liver disease by measuring sulfurous molecules in the breath. Risby said he had some doubts about the immediate use of the new laser method, because it's far easier to measure chemicals in the breath than it is to understand why they are there. Ethane, for example, can show up in the breath of a person who is developing cancer, he said — or the chemical's presence could instead signal an absence of fruit and vegetables in the diet. "If you don't understand what you're doing, you can do more a disservice than anything else," Risby said. For the new work, published online in the peer-reviewed journal Optics Express, Ye, Thorpe and two co-authors relied on an "optical frequency comb," a technique developed in the 1990s by Jan Hall, a CU physicist who shared the 2005 Nobel Prize in physics for his work. The Boulder team asked volunteers to breathe into a device called an optical cavity, and then bounced laser light of many frequencies through the cavity. Molecules in the breath absorbed light of different wavelengths, Ye said, so scientists could figure out what chemicals were present — even in tiny amounts of parts per billion — by studying the laser light that left the cavity. In samples from student volunteers, Ye and his colleagues found the fingerprints of ammonia, carbon monoxide and methane. They were able to identify a smoker by the elevated levels of carbon monoxide in that person's breath, Ye said. Approved devices let doctors monitor asthma, by tracking nitric-oxide levels, and pick up some ulcers, by measuring carbon compounds. Those techniques rely on either the expensive and time-intensive technique of mass spectrometry — a set-up can cost $1 million, Thorpe said — or on devices that measure only one or two constituents of breath. "Our idea is that if you could detect a bunch of these at the same time, you could decrease your false positives, or target the disease better," he said.
Poster Comment: Looks like people are now paying attention to a dog's ability to diagnose disease, such as cancer.
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