Blow into the tube... get a diagnosis!
Scientists of the National Institute of Standards and Technology of the USA and the University of Colorado, working under the guidance of Dr. Jun Ye, demonstrated the possibility of detecting molecular markers of various diseases by shining the exhaled air with a laser beam.
Exhaled air contains less oxygen and more carbon dioxide than inhaled, and most importantly – trace amounts of thousands of different compounds evaporated from the surface of the alveoli.
By bad breath, it is not difficult to detect problems with teeth or stomach. An imperceptible, but increased content of methylamine in the exhaled air compared to the norm indicates kidney and liver diseases, ammonia can be a sign of kidney failure, a high level of acetone indicates diabetes, and the concentration of nitric oxide can be used to diagnose asthma.
Simultaneous detection of a multitude of exhaled molecules provides the most reliable information about problems in the body. The diagnosis of asthma, for example, will be much more reliable if the levels of carbon dioxide, carbon monoxide, hydrogen peroxide and nitrogen oxide are simultaneously determined.
Existing methods of exhaled air analysis are non-invasive and inexpensive procedures, but their capabilities are very limited due to the low selectivity and sensitivity of equipment that does not allow recording a wide range of compounds and their trace amounts.
The new method, which is based on the use of the so-called "optical frequency comb" (optical frequency comb technique), is a much more effective alternative.
The method developed in the 1990s is based on the fact that a laser beam is a set of photons with a very narrow range. Their energy depends on the frequency of the photons' vibrations, and by carefully changing the wavelength, it is possible to select frequencies that resonate with the vibration frequency of certain molecules. Jun Ye and colleagues proposed for the first time to use an optical frequency comb in spectroscopy to simultaneously detect a wide range of gases.
To test the medical application of the method, the authors offered volunteer students to breathe into an optical resonator - a cavity between two curved mirrors, after which they sent ultrashort (femtosecond) laser pulses into the resonator. After hundreds of thousands of reflections from mirror surfaces, the degree of absorption of light waves of various frequencies varied in accordance with the quantitative and qualitative molecular composition of the air.
At the same time, trace amounts of ammonia, carbon monoxide and methane were detected. Smokers were the easiest to distinguish: in the air they exhaled carbon monoxide contained 5 times more than non-smokers.
The proposed technique has yet to pass clinical trials, but the developers believe that over time it will greatly facilitate the screening of large groups of people for the detection of various diseases.
Article by Michael J. Thorpe et al. "Cavity-enhanced optical frequency comb spectroscopy: application to human breath analysis" published in Optics Express magazine on February 18, 2008.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
21.02.2008