Saliva is an easily accessible body fluid containing important biological markers of physiological regulation in the body. The ability to use saliva to monitor the health and disease state of an individual is a highly desirable goal for health promotion and healthcare research. Saliva can reflect tissue levels of some natural substances and a large variety of molecules introduced for therapeutic use, emotional status, hormonal status, immunological status, neurological effects, and nutritional and metabolic status. A major drawback of using saliva as a diagnostic fluid has been that analytes (substances undergoing analysis) are generally present in lower amounts in saliva than in blood.
As a research tool, saliva has many advantages over blood. Saliva is easy to collect, store, and ship, and it can be obtained at low cost and in sufficient quantities for analysis. For patients, the noninvasive collecting techniques dramatically reduce anxiety and discomfort, and simplify the gathering of repeated samples for longitudinal monitoring over time. Saliva does not clot, lessening the manipulations required. Saliva-based diagnostics are therefore more accessible, accurate, and less expensive than current methodologies.
A novel collection device for human saliva samples was developed. The primary goal was to assess salivary cortisol and dehydroeiandrosterone (DHEA) during spaceflight. However, the collection device can be used at any remote location, including space, and does not require any special conditions for storage. The Saliva Procurement and Integrated Testing (SPIT) booklets contain multiple filter paper pages that allow for the collection of multiple saliva samples over a specified time. Saliva samples are collected on the filter paper and are dried at room temperature. The samples are stable for as long as six months for measurement of both cortisol and DHEA, two important stress and immune regulatory hormones. These booklets are currently being used to collect saliva samples from International Space Station crewmembers before, during, and after spaceflight. The innovation can be used for rapid collection of saliva in remote locations, and analysis is performed upon return to a laboratory.
Five saliva specimens are collected using the SPIT booklet. Steroid hormones are then measured using commercially available, high-sensitivity kits. Subjects moisten a filter paper immediately after waking, 30 minutes later, before lunch, 10 hours after waking, and before going to bed at night. They collect these samples on a typical collection day. On the booklet cover, the time of collection is recorded. Samples associated with poor wetting or missing a sample are addressed by a mixed models analysis. After drying, the booklets are placed in a plastic bag and returned via the mail. The 10-hour interval is required for a fixed-minute time frame to determine the area under the CORT and DHEA curves, and for computing molar ratios of CORT/DHEA while remaining within the detection limits of the assay.
This work was done by Duane Pierson of Johnson Space Center, Satish Mehta of EASI/Johnson Space Center/NASA, and Mark Laudenslager of the University of Colorado Health Sciences Center. For more information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-25155-1