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Friday, April 5, 2013
Exhaled breath carries a molecular 'breathprint' unique to each individual
Apr. 3, 2013 ? Stable, specific 'breathprints' unique to an individual exist and may have applications as diagnostic tools in personalized medicine. Bodily fluids contain lots of information about the health status of a person. Medical doctors routinely have blood and urine analysed in order to obtain hints for infectious and metabolic diseases, to diagnose cancer and organ failure, and to check the dose of medication, based on compounds present in these body fluids.
Researchers at ETH Zurich and at the University Hospital Zurich now propose to extend such analyses to breath, and in particular to take advantage of modern high-resolution analytical methods that can provide real-time information on the chemical composition of exhaled breath.
Unbiased Chemical Analysis of Breath
The scientists developed an instrument-based version of a principle that has been known for a long time in traditional Chinese medicine: TCM doctors draw conclusions about the health state of a patient based on the smell of the exhaled breath. It is also known that trained dogs and rats can distinguish the smell of the breath of people suffering from certain variants of cancer. In these cases the entire smell of the patient's exhaled breath is gauged, which can give rise to bias. The scientists, led by Renato Zenobi, professor at the Laboratory for Organic Chemistry, aim at eliminating this bias and identifying the chemical compounds in breath. Like this, doctors should be able to use specific compounds, which are present in breath at minute concentrations, for medical diagnosis.
Using mass spectrometry, these goals can be reached, as shown in a recent study where the ETH researchers analysed the exhaled breath of eleven volunteers. They found that the chemical "fingerprint" of exhaled breath, largely based on volatile and semi-volatile metabolites, shows an individual core pattern. Each volunteer was found to have his/her own characteristic "breathprint."
Stable Pattern
Using regular measurements extending over 11 days, the researchers could furthermore show that this metabolic "breathprint" stays constant. "We did find some small variations during the day, but overall the individual pattern stays sufficiently constant to be useful for medical purposes," says Pablo Martinez-Lozano Sinues, senior scientist in Zenobi's research group. If the measurements would show too large variations, they would not be useful for medical diagnosis.
To carry out these measurements, Zenobi and his colleagues modified commercial mass spectrometers, for example by adding a breath sampling inlet line that delivers exhaled breath from a mouth piece directly into the ion source of the instrument. Mass spectra showing peaks of roughly 100 compounds in breath can be easily and rapidly obtained in this fashion. The researchers were able to identify acetone, a product of the sugar metabolism. Most of the other signals present in the "breathprints" have not been assigned yet, which is something the scientists have on their to-do-list.
Chemical fingerprints of diseases
The next step the ETH chemists plan to take is not only to elucidate the personal breathprints of individuals, but to recognize characteristic patterns of diseases with the same technology. For this endeavour, they are collaborating with medical doctors at the Division of Pulmonology of the University Hospital Zurich. "If we find a consistent pattern in patients with a given lung disease, we can develop a diagnostic tool," explains Sinues. They believe that their chances are highest to find characteristic biomarkers in the exhaled breath of patients with lung diseases, which is why they focus on these disorders. In the future, they hope to extend their methodology to other groups of diseases.
Although the potential usefulness of analysing breath for medical diagnosis has been known, it is rarely done in academic medicine. "This might be due to the fact that existing methods for breath analysis are either rather slow, or are limited to a small number of compounds that they can detect," says Sinues.
Compared to analysis of blood or urine, a significant advantage of the approach the ETH researchers have taken is that the breath fingerprint is available within seconds after delivering the breath sample. Analysing urine or blood in a specialized laboratory usually takes a lot longer. Another advantage is that exhaling into the ion source of a mass spectrometer is completely non-invasive, i.e., there is no need to poke the patient with a needle (when a blood sample is taken). "Our goal is to develop breath analysis to the point where it becomes competitive with the established analysis of blood and urine," says Malcolm Kohler, professor at the University Hospital Zurich, and one of the co-authors of the study. Regular survey of breath could, for example, be used to obtain an early warning for healthy persons with a known risk for a certain disease. It is also imaginable to monitor the progress or the side effects of an on-going medical therapy.
For this method to be accepted in the clinic, the instrumentation has to be improved. The highly sensitive and accurate mass spectrometers that are currently used for these analyses are large and expensive. Zenobi: "Small, portable mass spectrometers already exist; if their performance can be improved, they will eventually find their way into clinics and doctor's offices."
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The above story is reprinted from materials provided by ETH Zurich, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Martinez-Lozano Sinues P, Kohler M, Zenobi R. Human Breath Analysis May Support the Existence of Individual Metabolic Phenotypes. PLoS ONE, 2013; 8(4): e59909 DOI: 10.1371/journal.pone.0059909
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/5MoT-aJz4wQ/130403200254.htm
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Remains of the Day: Google Now Update Adds Real-Time Package Tracking Card
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Thursday, April 4, 2013
Shark tooth weapons reveal missing shark species in Central Pacific islands
Apr. 3, 2013 ? The Gilbert Island reefs in the Central Pacific were once home to two species of sharks not previously reported in historic records or contemporary studies. The species were discovered in a new analysis of weapons made from shark teeth and used by 19th century islanders, reported in a study published April 3 in the open access journal PLOS ONE by Joshua Drew from Columbia University and colleagues from the Field Museum of Natural History.
Sharks were culturally important to the Gilbertese Islanders; historic records indicate a complex ritual system surrounding shark fishing and making fishing gear and weapons from shark teeth. For the current study, the researchers analyzed a collection of 120 of these weapons from the Field Museum of Natural History, including some that resemble clubs, daggers, lances, spears and swords. They identified eight species of sharks based on the teeth used in these weapons, two of which have never been reported from these waters, in either historical surveys or contemporary analysis. Both these species are currently common in other areas, so while it is possible that these species may still be living undiscovered in the GIlberts, it is more likely that the local populations have been driven to extinction.
"When we looked we found this shadow biodiversity, hints and whispers of what these reefs used to be like. It's our hope that by understanding how reefs used to look we'll be able to come up with conservation strategies to return them to their former vivid splendor," says Drew.
According to the study, sharks in these waters play important ecological and cultural roles, and understanding the historical ecological conditions of these reefs is an important first step in evaluating conservation efforts.
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The above story is reprinted from materials provided by Public Library of Science.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Drew J, Philipp C, Westneat MW. Shark Tooth Weapons from the 19th Century Reflect Shifting Baselines in Central Pacific Predator Assemblies. PLOS ONE, 2013; 8 (4): e59855 DOI: 10.1371/journal.pone.0059855
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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/PyCTwVNyGaM/130403200256.htm
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