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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9

Application of luciferase assay for ATP to antimicrobial drug susceptibility

The susceptibility of bacteria, particularly those derived from body fluids, to antimicrobial agents is determined in terms of an ATP index measured by culturing a bacterium in a growth medium. The amount of ATP is assayed in a sample of the cultured bacterium by measuring the amount of luminescent light emitted when the bacterial ATP is reacted with a luciferase-luciferin mixture. The sample of the cultured bacterium is subjected to an antibiotic agent. The amount of bacterial adenosine triphosphate is assayed after treatment with the antibiotic by measuring the luminescent light resulting from the reaction. The ATP index is determined from the values obtained from the assay procedures.

Chappelle, E. W.↗

Manual control analysis of drug effects on driving performance

The effects of secobarbital, diazepam, alcohol, and marihuana on car-driver transfer functions obtained using a driving simulator were studied. The first three substances, all CNS depressants, reduced gain, crossover frequency, and coherence which resulted in poorer tracking performance. Marihuana also impaired tracking performance but the only effect on the transfer function parameters was to reduce coherence.

Smiley, A.↗

The effects of horizontal body casting on blood volume, drug responsiveness, and +Gz tolerance in the rhesus monkey

To simulate the weightless condition, eight rhesus monkeys, instrumented with solid-state pressure transducers, were horizontally restrained in body casts for 28 days. Blood volume decreased an average of 13% after 14 days of restraint, due mainly to a drop in plasma volume. Aortic pressure and heart rate responses to norepinephrine and phenylephrine decreased after 14 days of restraint. The monkeys did not show a statistically significant decreased tolerance to a 90 deg sudden upright tilt after horizontal restraint. During the fifth week of casting, four animals were subjected to +Gz acceleration tests on a centrifuge. The acceleration tolerance of the casted monkeys was significantly reduced compared to four similarly instrumented control animals. These findings indicate that the cardiovascular deconditioning associated with simulated weightlessness results from an inability to maintain central blood volume during orthostatic stress.

Dickey, D. T.↗

Changes in blood volume and response to vaso-active drugs in horizontally casted primates

Experiments were performed on horizontally casted primates (male rhesus monkeys) in order to note changes in blood volume caused by horizontal restraint, to compare orthostatic tolerance before and after casting using the responses to upright tilting, to begin to uncover the cardiovascular and neural mechanisms involved in deconditioning, and to compare the data with that obtained from bed-rested human subjects and from humans exposed to weightlessness. Bolus injections of norepinephrine of 2.0 microgram/kg, phenylephrine of 4.0 microgram/kg, and nitroprusside of 2.0 microgram/kg were administered; and aortic pressure and heart rate were recorded during the injections. The results indicate that the horizontally casted primate is a valid animal model for studying the effects of simulated zero-G on the human cardiovascular system.

Dickey, D. T.↗

Drug effects on orthostatic intolerance induced by bedrest

Effective and practical preventive procedures for postflight orthostatic intolerance are highly desirable. The current practice of attempts to expand plasma volume by ingestion of salt and fluids before reentry has proven benefits. This study evaluated alternative options using fludrocortisone (F) to expand plasma volume (PV), dextroamphetamine (Dex) to enhance norepinephrine (NE) release, and atropine (A) to reduce the effects of vagal stimulation. Seven subjects with proven post-bedrest orthostatic intolerance returned for a 7-day 6-deg head-down bedrest study. F (0.2 mg) was given at 8:00 AM and 8:00 PM the day before and 8:00 AM the day the subjects got out of bed (2 hours before standing). PV was measured before and 1 hour after the last dose of F. Dex (5 mg) and A (0.8 mg) were then taken orally 1 hour before the stand test. F expanded PV by 16 percent and caused sodium retention. Four of the 7 subjects stood for 1 hour post-bedrest and heart rate, plasma NE and plasma renin responses to standing were greatly enhanced and sustained. Although there was a narrowing of pulse pressure, the ability to overcome orthostatic intolerance with these countermeasures was largely due to vasoconstriction and sustained high heart rate.

Vernikos, J.↗

Administration of the non-steroidal anti-inflammatory drug ibuprofen increases macrophage concentrations but reduces necrosis during modified muscle use

OBJECTIVE: To test the hypothesis that ibuprofen administration during modified muscle use reduces muscle necrosis and invasion by select myeloid cell populations. METHODS: Rats were subjected to hindlimb unloading for 10 days, after which they experienced muscle reloading by normal weight-bearing to induce muscle inflammation and necrosis. Some animals received ibuprofen by intraperitoneal injection 8 h prior to the onset of muscle reloading, and then again at 8 and 16 h following the onset of reloading. Other animals received buffer injection at 8 h prior to reloading and then ibuprofen at 8 and 16 h following the onset of reloading. Control animals received buffer only at each time point. Quantitative immunohistochemical analysis was used to assess the presence of necrotic muscle fibers, total inflammatory infiltrate, neutrophils, ED1+ macrophages and ED2+ macrophages at 24 h following the onset of reloading. RESULT: Administration of ibuprofen beginning 8 h prior to reloading caused significant reduction in the concentration of necrotic fibers, but increased the concentration of inflammatory cells in muscle. The increase in inflammatory cells was attributable to a 2.6-fold increase in the concentration of ED2+ macrophages. Animals treated with ibuprofen 8 h following the onset of reloading showed no decrease in muscle necrosis or increase in ED2+ macrophage concentrations. CONCLUSION: Administration of ibuprofen prior to increased muscle loading reduces muscle damage, but increases the concentration of macrophages that express the ED2 antigen. The increase in ED2+ macrophage concentration and decrease in necrosis may be mechanistically related because ED2+ macrophages have been associated with muscle regeneration and repair.

Non-NASA Center↗

Three-Dimensional Cell Culture Models for Infectious Disease and Drug Development

Three-dimensional (3-D) cell cultures hold enormous potential to advance our understanding of infectious disease and to effectively translate basic cellular research into clinical applications. Using novel NASA bioreactor technology, the rotating wall vessel (RWV), we have engineered physiologically relevant 3-D human tissue culture models for infectious disease studies. The design of the RWV is based on the understanding that organs and tissues function in a 3-D environment, and that this 3-D architecture is critical for the differentiated form and function of tissues in vivo. The RWV provides large numbers of cells which are amenable to a wide variety of experimental manipulations and provides an easy, reproducible, and cost-effective approach to enhance differentiated features of cell culture models.

Nickerson, Cheryl A.↗

Effectiveness of Needles Vial Adaptors and Blunt Cannulas for Drug Administration in a Microgravity Environment

The need for a new system of injectable medications aboard the International Space Station (ISS) was identified. It is desired that this system fly medications in their original manufacturer's packaging, allowing the system to comply with United States Pharmacopeia (USP) guidelines while minimizing the resupply frequency due to medication expiration. Pre-filled syringes are desired, however, the evolving nature of the healthcare marketplace requires flexibility in the redesign. If medications must be supplied in a vial, a system is required that allows for the safe withdrawal of medication from the vial into a syringe for administration in microgravity. During two reduced gravity flights, the effectiveness of two versions of a blunt cannula and needleless vial adaptors was evaluated to facilitate the withdrawal of liquid medication from a vial into a syringe for injection. Other parameters assessed included the ability to withdraw the required amount of medication and whether this is dependent on vial size, liquid, or the total volume of fluid within the vial. Injectable medications proposed for flight on ISS were used for this evaluation. Due to differing sizes of vials and the fluid properties of the medications, the needleless vial adaptors proved to be too cumbersome to recommend for use on the ISS. The blunt cannula, specifically the plastic version, proved to be more effective at removing medication from the various sizes of vials and are the recommended hardware for ISS. Fluid isolation within the vials and syringes is an important step in preparing medication for injection regardless of the hardware used. Although isolation is a challenge in the relatively short parabolas during flight, it is not an obstacle for sustained microgravity. This presentation will provide an overview of the products tested as well as the challenges identified during the microgravity flights.

Hailey, Melinda↗