Salivary Markers of Metabolic Changes during Space Missions (Check-Saliva) - 07.29.14
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Salivary Markers of Metabolic Changes during Space Missions (Check-Saliva) tests crewmembers' saliva, blood, and urine before, during and after spaceflight to study whether saliva tests can serve as reliable health monitors. Long-term exposure to the microgravity environment results in reduced bone and muscle mass, which is related to changes in certain substances in the bloodstream and urine. Some of these changes can also be detected in saliva samples, so tests using Check-Saliva can validate whether saliva and/or urine can be used as simple, non-invasive tools to monitor crewmembers' bone and muscle status during a space mission.
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OpNom Bone/Muscle Check
Salerno University, , , Italy
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Italian Space Agency (ASI)
Earth Benefits, Space Exploration
ISS Expedition Duration
September 2014 - October 2015
Previous ISS Missions
- The reduction in bone/muscle mass secondary to microgravity exposure is a limiting step in the duration of space missions. The monitoring of the biochemical aspects of this reduction depends at present on the collection of blood and/or urine samples. The definition of other simple tools for monitoring the bone/muscle status could be of help in detection, treatment and control of the microgravity-induced reduction in bone/muscle mass.
The investigation aims to perform the following procedures:
- a. in the days preceding the space mission: measurements of bone/muscle mass together with collection of samples of saliva, blood, and urine;
- b. at different time-points during space mission: collection of samples of saliva and urine;
- c. at the completion of the space mission: measurements of bone/muscle mass together with collection of samples of saliva, blood, and urine.
- Samples of saliva, blood, and urine shall be frozen as rapidly as possible, and later analyzed for measurements of substances which reflect the bone/muscle metabolism.
The investigation will provide information on the reliability of saliva and urine as a simple and non-invasive tool to monitor changes in bone/muscle status during space mission. This information could be the first step in the development of space-designed devices for rapid measurements of markers of bone/muscle status. Theoretically, the use of saliva as marker of the blood composition could be of use in other microgravity-induced disorders, as well as in medicine on Earth.
The research focuses on the use of saliva and urine as a non-invasive tool to monitor some of the metabolic changes secondary to the microgravity-induced reduction in bone/muscle mass.
A number of previous observations show that exposure to microgravity results in a reduction of bone and muscle mass. These effects are a limiting step in the duration of space mission. Similar effects on bone and muscle mass are induced by prolonged bed-rest, that is, by the experimental condition which is used to simulate microgravity on Earth. The reduction in bone and muscle mass is associated with changes in blood levels and, secondarily, in urine levels, of several substances, which are used in research and clinical practice, as markers of bone or muscle metabolism. A recent program of the Italian Space Agency (ASI) included a set of bed-rest experiments which confirmed and extended these previous observations.
Saliva and urine are biological fluids which can be easily and repeatedly collected without risks. Past and recent data from different laboratories consistently indicate that the chemical composition of saliva and urine reflects, in many aspects, the chemical composition of blood. This is true also for some markers of bone or muscle conditions. In fact, saliva, urine, and blood tend to have similar levels of bone mineral components (calcium and phosphate), of bone-related vitamins (vitamin D), and of end-products of muscle protein (urea), etc.
The research includes pre-flight procedures, in-flight procedures, and post-flight procedures.Pre-flight and post-flight measurements of bone/muscle mass serve to verify the presence of the expected mass reduction after the space mission. This set of measurements is done by leg peripheral Quantitative Computed Tomography, an X-ray based method which is currently used in medical practice (pQCT, Stratec, Germany).
Biological samples are collected pre-flight (blood, urine, and saliva), in flight (urine and saliva), and post-flight (blood, urine and saliva). They will be rapidly frozen for later laboratory work-up on specific markers of bone/muscle metabolism.
In-flight urinary samples will be compared to pre-flight urinary samples to verify the presence of expected modifications in those markers due to microgravity exposure during the space mission. In-flight saliva samples and pre-flight saliva samples are compared to assess if some of the modifications in urinary markers are present and detectable in saliva also. Pre-flight and post-flight blood samples will serve as reference for urinary samples and as comparator with previous data.
Blood-based measurements are effective, but saliva-based detection of metabolic changes would be simpler and less invasive for use in spaceflight. If the results support testing saliva for the presence of biological markers, future automated devices could rapidly test saliva instead of blood samples before, during and after space missions.
If saliva can be used as a reliable indicator of bone and muscle health, it may also be used as a simple, automated, non-invasive clinical tool on Earth. Salivary markers could be used to test for certain medical conditions in settings where blood samples are difficult or impossible, including in remote areas, for young children, or for large-scale screening of a general population.
The crewmembers are invited to perform pre-flight, in-flight, and post-flight procedures. Pre-flight procedures include measurements of bone/muscle mass by pQCT together with collection of biological samples (saliva, blood, and urine). In-flight procedures include only the non-invasive collection of biological samples (saliva and urine). Post-flight procedures will mirror Pre-flight procedures (measurements of bone/muscle mass by pQCT together with collection of biological samples).
The measurements of bone/muscle mass, and the collection of biological samples, require standardized conditions: a 20 min rest (still sit) for bone/muscle measurements, and 3-4 hours of fasting after morning breakfast for the collection biological samples. The protocol on Earth mirrors the protocol on ISS.
- Pre-flight procedures are performed by the PI group in the days preceding the space mission and will include: measurements of bone/muscle mass by pQCT together with the collection of samples of saliva, blood, and urine.
- In-flight procedures should be performed by crewmembers at different time-points during space mission and will include: collection of samples of saliva and urine samples; labeling, freezing, and storage of the samples. The participating crewmembers are asked to collect samples of saliva at three, or more, separate time points. The research focuses on saliva and, secondarily, on urine. Urinary samples are used to verify the presence/absence at given time points of the expected changes in urinary markers of bone and muscle metabolism.
- Post-flight procedures are performed by the PI group at completion of the space mission and mirror Pre-flight procedures (measurements of bone/muscle mass by pQCT together with collection of samples of saliva, blood, and urine).
Pre-flight and post-flight biological samples are rapidly frozen for subsequent lab work-up. Crewmembers are asked to label and freeze the samples collected on ISS. All frozen biological samples undergo specific work-up by commercially available kits in the laboratory of the PI.
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