Drug Detection through Biosensors.

Abstract

Space Motion Sickness (SMS) afflicts astronauts during space shuttle missions. The symptoms of SMS include headache, vomiting, nausea, extreme sensitivity to motion, as well as some other minor maladies. SMS occurs often and may be so severe that it negatively impacts the operation of extravehicular activities (such as space walks, and routine duties outside the shuttle cabin). To treat the symptoms of SMS, NASA implemented the use of Promethazine (PMZ) intramuscularly (IM). The choice of the IM route was due to gastric motility and drug loss during liver metabolism if taken orally. IM PMZ taken on the ground causes side effects such as sedation and nausea, which were of concern to NASA. As a result, NASA undertook a study of 14 Space Shuttle missions prior to 1989. Of the 21 subjects studied who took IM PMZ for SMS, only one felt any sedation but did not experience any effects on his operating skills. Overall, this study showed sedation in only 4.8% of those taking PMZ in space, in comparison to a 70% on earth. This result leads to the question of differences in pharmocokinetics and bioavailability of drugs in space and on earth. Persechini et al, has shown that, through the use of a GFP FRET (Green Fluorescent Protein Frequency Resonance Emission Transfer), intracellular calcium can be detected by a change of fluorescent intensity. This recombinant molecule is composed of two variants (red-shifted fluorescent protein (RGPF) and blue-shifted fluorescent protein (BGFP) and a calmodulin linker (a linker sequence that binds free calcium). When the RGFP and BGFP are close together they share a resonance, but when calcium binds to the linker, the 2 variants are pulled apart, taking away the FRET and changing the fluorescent activity. The focus of my research is to create a GFP FRET device to monitor IM PMZ metabolism in a non-invasive fashion. PMZ is a phenothiazine derivative, which binds to both D1 and D2 dopamine receptor. I will replace the calmodulin linker with an extracellular component of both dopamine receptors, resulting in two types of GFP FRET: a D1 GFP FRET and a D2 GFP FRET.