Sleep Homeostasis and General Anesthesia: Are Fruit Flies Well Rested after Emergence from Propofol?

BACKGROUND: Shared neurophysiologic features between sleep and anesthetic-induced hypnosis indicate a potential overlap in neuronal circuitry underlying both states. Previous studies in rodents indicate that preexisting sleep debt discharges under propofol anesthesia. The authors explored the hypothesis that propofol anesthesia also dispels sleep pressure in the fruit fly. To the authors' knowledge, this constitutes the first time propofol has been tested in the genetically tractable model, Drosophila melanogaster. METHODS: Daily sleep was measured in Drosophila by using a standard locomotor activity assay. Propofol was administered by transferring flies onto food containing various doses of propofol or equivalent concentrations of vehicle. High-performance liquid chromatography was used to measure the tissue concentrations of ingested propofol. To determine whether propofol anesthesia substitutes for natural sleep, the flies were subjected to 10-h sleep deprivation (SD), followed by 6-h propofol exposure, and monitored for subsequent sleep. RESULTS: Oral propofol treatment causes anesthesia in flies as indicated by a dose-dependent reduction in locomotor activity (n = 11 to 41 flies from each group) and increased arousal threshold (n = 79 to 137). Recovery sleep in flies fed propofol after SD was delayed until after flies had emerged from anesthesia (n = 30 to 48). SD was also associated with a significant increase in mortality in propofol-fed flies (n = 44 to 46). CONCLUSIONS: Together, these data indicate that fruit flies are effectively anesthetized by ingestion of propofol and suggest that homologous molecular and neuronal targets of propofol are conserved in Drosophila. However, behavioral measurements indicate that propofol anesthesia does not satisfy the homeostatic need for sleep and may compromise the restorative properties of sleep.

Microtransponder-based multiplex assay for genotyping cystic fibrosis.

BACKGROUND: We developed and evaluated a genotyping assay for detection of 50 cystic fibrosis (CF) mutations. The assay is based on small (500 microm) electronic chips, radio frequency (RF) microtransponders (MTPs). The chips are analyzed on a unique fluorescence and RF readout instrument. METHODS: We divided the CF assay into 4 panels: core, Hispanic, African-American, and Caucasian. We amplified 18 CF transmembrane regulator (CFTR) DNA fragments covering 50 mutations by use of multiplex PCR using 18 CFTR gene-specific primer pairs. PCR was followed by multiplex allele-specific primer extension (ASPE) reactions and hybridization to capture probes synthesized on MTPs. We used 100 ASPE primers and 100 capture probes. We performed fluorescence measurements of hybridized MTP kits and assay analysis using a custom automated bench-top flow instrument. RESULTS: We validated the system by performing the assay on 23 commercial DNA samples in an internal study and 32 DNA samples in an external study. For internal and external studies, correct calls were 98.8% and 95.7%, false-positive calls 1.1% and 3.9%, and false-negative calls 0.12% and 0.36%, respectively. CONCLUSIONS: The MTP-based multiplex assay and analysis platform can be used for CF genotyping.

Microtransponders, the miniature RFID electronic chips, as platforms for cell growth in cytotoxicity assays.

BACKGROUND: An electronic radio frequency (RF) microchip, the microtransponder (MTP), has been developed as a platform for assays in the fields of genomics and proteomics. Upon activation by light, each MTP provides a unique RF identification (ID) signal that matches a chip to the specific biological material attached to it. The MTP is powered by a photocell and has an antenna that transmits the signal. The aim of the present study was to explore utility of MTPs as a platform for cell growth in cytotoxicity assays. METHODS: The MCF-7, MCF-116, A549, or T-24 cells growing on MTPs placed in petri dishes or slide chambers were cultured untreated or exposed to antitumor drugs topotecan, mitoxantrone, or onconase for up to 4 days. Their attachment to- and growth on- MTPs was assessed by fluorescence microscopy and laser scanning cytometry (LSC) and compared with growth on the dish surface in the MTP neighborhood. The MTPs were fixed in ethanol, stained with propidium iodide (PI), and interrogated in flow in the instrument capable to rapidly (up to 103 MTPs/s) identify their ID signal and measure fluorescence. RESULTS: The cells plated on MTPs exhibited similar attachment properties to those plated in culture dishes. When measured by LSC, they had similar mitotic activity, growth rate, and cell cycle distributions as the cells adhering to the culture dish in the neighborhood of MTPs. The fluorescence intensity of MTPs provided information about the cell number per MTP, which made it possible to assess cell growth rate and monitor the cytostatic/cytotoxic effects of the tested drugs. CONCLUSIONS: The MTP-based system holds promise for the multiplexed cell assays in which numerous different cell lines can be screened for their growth rate or sensitivity while exposed to particular agents in the same vessel. Other advantages of the system are the rapidity of the screening and a very large number of ID codes. Because many cell lines/types can be assayed in a single dish, the system also offers cost savings on tissue culture reagents.