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PubMed1996

Determining blood and plasma volumes using bioelectrical response spectroscopy.

We hypothesized that an electric field (inductance) produced by charged blood components passing through the many branches of arteries and veins could assess total blood volume (TBV) or plasma volume (PV). Individual (N = 29) electrical circuits (inductors, two resistors, and a capacitor) were determined from bioelectrical response spectroscopy (BERS) using a Hewlett Packard 4284A Precision LCR Meter. Inductance, capacitance, and resistance from the circuits of 19 subjects modeled TBV (sum of PV and computed red cell volume) and PV (based on 125I-albumin). Each model (N = 10, cross validation group) had good validity based on 1) mean differences (-2.3 to 1.5%) between the methods that were not significant and less than the propagated errors (+/- 5.2% for TBV and PV), 2) high correlations (r > 0.92) with low SEE (< 7.7%) between dilution and BERS assessments, and 3) Bland-Altman pairwise comparisons that indicated "clinical equivalency" between the methods. Given the limitation of this study (10 validity subjects), we concluded that BERS models accurately assessed TBV and PV. Further evaluations of the models' validities are needed before they are used in clinical or research settings.

Adult↗
PubMed1995

Assessing total body protein, mineral, and bone mineral content from total body water and body density.

We hypothesized that investigators could assess bone mineral content (BMC), total body mineral (M), and protein (P) from body water (W) and density (DB) based on the theory of W. E. Siri (Advances in Biological and Medical Physics, 1956, p. 239-280 and Techniques for Measuring Body Composition, 1961, p. 223-224) for body composition analysis. Siri used one or more of the body components and the densities of the body, fat (F), W, M, and P to estimate one of the remaining fractional masses. We compared M, BMC, P. F, and fat-free mass (FFM) in 31 subjects (15 women and 16 men) computed from measurements of W and DB with [4-compartment (4C) model] and without [3-compartment (3C) model] BMC (from dual X-ray absorptiometry). 4C model P was calculated by difference (P = FFM - W - M). Mean difference (P > 0.05) ranged from 0.1 to 0.8%. Correlations [+/- standard error of estimate (%)] between 4C and 3C model values were significant (r = 0.907 +/- 8.8, 0.907 +/- 8.7, 0.969 +/- 6.6, 0.998 +/- 2.0, and 0.999 +/- 0.7% for M, BMC, P, F, and FFM, respectively). We concluded that investigators can assess M, BMC, and P from W and DB.

Adult↗
PubMed2005

In-flight medical incidents in the NASA-Mir program.

This paper summarizes medical experience during the six NASA-Mir flights from March 14, 1995, to June 4, 1998. There were 7 U.S. astronauts who were part of 6 Mir space crews and worked jointly with 12 Russian cosmonauts. Advances in space medicine have created a safer environment; however, experience shows that crewmembers experience traumatic injuries and illnesses of diverse etiologies during spaceflight. During these joint flights both Russian and U.S. medical kits were available to crewmembers who could access either medical kit as appropriate. The Russian medical team had primary responsibility for monitoring and care of all crewmembers and analyzing medical results. When medical incidents occurred, the appropriate Russian or U.S. medical team determined the plan for diagnosis and treatment. Each team kept the other informed regarding medical situations during the flights and strictly observed the principles of medical confidentiality. A summary of medical incidents by programmatic element is described as experienced by the crewmembers and the ground support medical teams. The most frequent medical cases were small traumatic injuries to the skin and mucous membranes and fluctuations in the cardiovascular system, manifesting primarily in the form of cardiac dysrhythmias. The ability to use both the Russian medical aids and the U.S. medical kit significantly increased the effectiveness and reliability of therapeutic and prophylactic care. The degree of medical care and cooperation established precedents for integrating these systems for the medical support of expeditions on the International Space Station.

Aerospace Medicine↗
PubMed1994

Controlled Ecological Life Support Systems (CELSS) flight experimentation.

The NASA CELSS program has the goal of developing life support systems for humans in space based on the use of higher plants. The program has supported research at universities with a primary focus of increasing the productivity of candidate crop plants. To understand the effects of the space environment on plant productivity, the CELSS Test Facility (CTF) has been been conceived as an instrument that will permit the evaluation of plant productivity on Space Station Freedom. The CTF will maintain specific environmental conditions and collect data on gas exchange rates and biomass accumulation over the growth period of several crop plants grown sequentially from seed to harvest. The science requirements of the CTF will be described, as will current design concepts and specific technology requirements for operation in micro-gravity.

Crops, Agricultural↗
PubMed2003

Initial closed operation of the CELSS Test Facility Engineering Development Unit.

As part of the NASA Advanced Life Support Flight Program, a Controlled Ecological Life Support System (CELSS) Test Facility Engineering Development Unit has been constructed and is undergoing initial operational testing at NASA Ames Research Center. The Engineering Development Unit (EDU) is a tightly closed, stringently controlled, ground-based testbed which provides a broad range of environmental conditions under which a variety of CELSS higher plant crops can be grown. Although the EDU was developed primarily to provide near-term engineering data and a realistic determination of the subsystem and system requirements necessary for the fabrication of a comparable flight unit, the EDU has also provided a means to evaluate plant crop productivity and physiology under controlled conditions. This paper describes the initial closed operational testing of the EDU, with emphasis on the hardware performance capabilities. Measured performance data during a 28-day closed operation period are compared with the specified functional requirements, and an example of inferring crop growth parameters from the test data is presented. Plans for future science and technology testing are also discussed.

Air Conditioning↗
PubMed2001

The NASA astrobiology program.

The new discipline of astrobiology addresses fundamental questions about life in the universe: "Where did we come from?" "Are we alone in the universe?" "What is our future beyond the Earth?" Developing capabilities in biotechnology, informatics, and space exploration provide new tools to address these old questions. The U.S. National Aeronautics and Space Administration (NASA) has encouraged this new discipline by organizing workshops and technical meetings, establishing a NASA Astrobiology Institute, providing research funds to individual investigators, ensuring that astrobiology goals are incorporated in NASA flight missions, and initiating a program of public outreach and education. Much of the initial effort by NASA and the research community was focused on determining the technical content of astrobiology. This paper discusses the initial answer to the question "What is astrobiology?" as described in the NASA Astrobiology Roadmap.

Academies and Institutes↗
PubMed1998

Overview of the Environmental Control and Life Support System (ECLSS) testing at MSFC.

Previously, almost all water used by the crew during space flight has been transported from earth or generated inflight as a by-product of fuel cells. Additionally, this water has been stored and used for relatively short periods. To achieve the United States' commitment to a permanent manned presence in space, more innovative techniques are demanded. Over 20,000 pounds of water and large quantities of air would have to be transported to the International Space Station (ISS) every 90 days with a corresponding amount of waste returned to earth, for an eight-person crew. This approach results in prohibitive logistics costs, and necessitates near complete recovery and recycling of water. The potential hazards associated with long-term reuse of reclaimed water and revitalized air resulted in the recognition that additional characterization of closed-loop systems and products is essential. Integrated physical/chemical systems have been designed, assembled, and operated to provide air and potable water meeting ISS quality specifications. The purpose of the Environmental Control and Life Support System (ECLSS) test program at NASA's Marshall Space Flight Center (MSFC) is to conduct testing related to the performance of the ISS and its Environmental Control components. The ECLSS Test Program encompasses the Water Recovery Test (WRT), the Integrated Air Revitalization Test (IART), and Life Testing, which permits ECLSS design evaluation. These subsystems revitalize air and reclaim waste waters representative of those to be generated on-orbit. This article provides an overview of MSFC's ECLSS testing. Specific tests include: the Stage 10 Water Recovery Test; the Contaminant Injection Test; the Four-Bed Molecular Sieve Performance Enhancement Test; and Life Testing.

Air Conditioning↗
PubMed2005

Porous media matric potential and water content measurements during parabolic flight.

Control of water and air in the root zone of plants remains a challenge in the microgravity environment of space. Due to limited flight opportunities, research aimed at resolving microgravity porous media fluid dynamics must often be conducted on Earth. The NASA KC-135 reduced gravity flight program offers an opportunity for Earth-based researchers to study physical processes in a variable gravity environment. The objectives of this study were to obtain measurements of water content and matric potential during the parabolic profile flown by the KC-135 aircraft. The flight profile provided 20-25 s of microgravity at the top of the parabola, while pulling 1.8 g at the bottom. The soil moisture sensors (Temperature and Moisture Acquisition System: Orbital Technologies, Madison, WI) used a heat-pulse method to indirectly estimate water content from heat dissipation. Tensiometers were constructed using a stainless steel porous cup with a pressure transducer and were used to measure the matric potential of the medium. The two types of sensors were placed at different depths in a substrate compartment filled with 1-2 mm Turface (calcined clay). The ability of the heat-pulse sensors to monitor overall changes in water content in the substrate compartment decreased with water content. Differences in measured water content data recorded at 0, 1, and 1.8 g were not significant. Tensiometer readings tracked pressure differences due to the hydrostatic force changes with variable gravity. The readings may have been affected by changes in cabin air pressure that occurred during each parabola. Tensiometer porous membrane conductivity (function of pore size) and fluid volume both influence response time. Porous media sample height and water content influence time-to-equilibrium, where shorter samples and higher water content achieve faster equilibrium. Further testing is needed to develop these sensors for space flight applications.

Biosensing Techniques↗
PubMed2000

Laboratory outreach: student assessment of flow cytometer fluidics in zero gravity.

Due to the the clinical utility of the flow cytometer, the National Aeronautics and Space Administration (NASA) is interested in the design of a space flight-compatible cytometer for use on long-duration space missions. Because fluid behavior is altered dramatically during space flight, it was deemed necessary to validate the principles of hydrodynamic focusing and laminar flow (cytometer fluidics) in a true microgravity environment. An experiment to validate these properties was conducted by 12 students from Sweetwater High School (Sweetwater, TX) participating in the NASA Reduced Gravity Student Flight Opportunity, Class of 2000. This program allows high school students to gain scientific experience by conducting an experiment on the NASA KC-135 zero gravity laboratory aircraft. The KC-135 creates actual zero-gravity conditions in 30-second intervals by flying a highly inclined parabolic flight path. The experiment was designed by their mentor in the program, the Johnson Space Center's flow cytometrist Brian Crucian, PhD, MT(ASCP). The students performed the experiment, with the mentor, onboard the NASA zero-gravity research aircraft in April 2000.

Aircraft↗
PubMed1997

Using Spacelab as a precursor of science operations for the Space Station.

For more than 15 years, Spacelab, has provided a laboratory in space for an international array of experiments, facilities, and experimenters. In addition to continuing this important work, Spacelab is now serving as a crucial stepping-stone to the improved science, improved operations, and rapid access to space that will characterize International Space Station. In the Space Station era, science operations will depend primarily on distributed/remote operations that will allow investigators to direct science activities from their universities, facilities, or home bases. Spacelab missions are a crucial part of preparing for these activities, having been used to test, prove, and refine remote operations over several missions. The knowledge gained from preparing these Missions is also playing a crucial role in reducing the time required to put an experiment into orbit, from revolutionizing the processes involved to testing the hardware needed for these more advanced operations. This paper discusses the role of the Spacelab program and the NASA Marshall Space Flight Center- (MSFC-) managed missions in developing and refining remote operations, new hardware and facilities for use on Space Station, and procedures that dramatically reduce preparation time for flight.

Equipment Design↗
PubMed1995

Effect of spaceflight on oxidative and antioxidant enzyme activity in rat diaphragm and intercostal muscles.

There are limited data regarding changes in oxidative and antioxidant enzymes induced by simulated or actual weightlessness, and any additional information would provide insight into potential mechanisms involving other changes observed in muscles from animals previously flown in space. Thus, the NASA Biospecimen Sharing Program was an opportunity to collect valuable information. Oxidative and antioxidant enzyme levels, as well as lipid perioxidation, were measured in respiratory muscles from rats flown on board Space Shuttle mission STS-54. The results indicated that there was an increasing trend in citrate synthase activity in the flight diaphragm when compared to ground based controls, and there were no significant changes observed in the intercostal muscles for any of the parameters. However, lipid peroxidation was significantly (p<0.05) decreased in the flight diaphragm. These results indicate that 6 day exposure to microgravity may have a different effect on oxidative and antioxidant activity in rat respiratory muscles when compared to data from previous 14 day hindlimb suspension studies.

Animals↗
PubMed1998

Applications of telemedicine in the United States space program.

Since the beginning of human space flight, NASA has been placing humans in extreme and remote environments. There are many challenges in maintaining humans in outer space, including the provision of life-support systems, radiation shielding, and countermeasures for minimizing the effect of microgravity. Because astronauts are selected for their health, among other factors, disease and illness are minimized. However, it is still of great importance to have appropriate medical care systems in place to address illness and injury should they occur. With the exception of the Apollo program, exploration of space has been limited to missions that are within several hundred miles of the surface of the Earth. At the drawn of the 21st century and the new millennium, human exploration will be focused on operation of the International Space Station (ISS) and preparation for human missions to Mars. These missions will present inherent risks to human health, and, therefore, appropriate plans must be established to address these challenges and risks. Crews of long-duration missions must become more independent from ground controllers. New systems, protocols, and procedures are currently being perfected. Application of emerging technologies in information systems and telecommunications will be critical to inflight medical care. Application of these technologies through telemedicine will provide crew members access to information, noninvasive procedures for assessing health status, and guidance through the integration of sensors, holography, decision-support systems, and virtual environments. These technologies will also serve as a basis to enhance training and medical education. The design of medical care for space flight should lead to a redesign of the practice of medicine on Earth.

Computer Communication Networks↗
PubMed1999

The response of bone to unloading.

Skeletal unloading leads to decreased bone formation and decreased bone mass. Bone resorption is uncoupled from bone formation, contributing to the bone loss. During spaceflight bone is lost principally from the bones most loaded in the 1-g environment, and some redistribution of bone from the lower extremities to the head appears to take place. Although changes in calcitropic hormones have been demonstrated during skeletal unloading (PTH and 1,25(OH)2D decrease), it remains unclear whether such changes account for or are in response to the changes in bone formation and resorption. Bed rest studies with human volunteers and hindlimb elevation studies with rats have provided useful data to help explain the changes in bone formation during spaceflight. These models of skeletal unloading reproduce a number of the conditions associated with microgravity, and the findings from such studies confirm many of the observations made during spaceflight. Determining the mechanism(s) by which loading of bone is sensed and translated into a signal(s) controlling bone formation remains the holy grail in this field. Such investigations couple biophysics to biochemistry to cell and molecular biology. Although studies with cell cultures have revealed biochemical responses to mechanical loads comparable to that seen in intact bone, it seems likely that matrix-cell interactions underlie much of the mechanocoupling. The role for systemic hormones such as PTH, GH, and 1,25(OH)2D compared to locally produced factors such as IGF-I, PTHrP, BMPs, and TGF-beta in modulating the cellular response to load remains unclear. As the mechanism(s) by which bone responds to mechanical load with increased bone formation are further elucidated, applications of this knowledge to other etiologies of osteoporosis are likely to develop. Skeletal unloading provides a perturbation in bone mineral homeostasis that can be used to understand the mechanisms by which bone mineral homeostasis is maintained, with the expectation that such understanding will lead to effective treatment for disuse osteoporosis.

Animals↗
PubMed2001

Effect of NASA light-emitting diode irradiation on wound healing.

OBJECTIVE: The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing. BACKGROUND DATA: Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans. MATERIALS AND METHODS: In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation. RESULTS: LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis. CONCLUSION: We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program.

Animals↗
PubMed2003

Effect of NASA light-emitting diode irradiation on molecular changes for wound healing in diabetic mice.

OBJECTIVE: The purpose of this study was to assess the changes in gene expression of near-infrared light therapy in a model of impaired wound healing. BACKGROUND DATA: Light-Emitting Diodes (LED), originally developed for NASA plant growth experiments in space, show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper we present the effects of LED treatment on wounds in a genetically diabetic mouse model. MATERIALS AND METHODS: Polyvinyl acetal (PVA) sponges were subcutaneously implanted in the dorsum of BKS.Cg-m +/+ Lepr(db) mice. LED treatments were given once daily, and at the sacrifice day, the sponges, incision line and skin over the sponges were harvested and used for RNA extraction. The RNA was subsequently analyzed by cDNA array. RESULTS: Our studies have revealed certain tissue regenerating genes that were significantly upregulated upon LED treatment when compared to the untreated sample. Integrins, laminin, gap junction proteins, and kinesin superfamily motor proteins are some of the genes involved during regeneration process. These are some of the genes that were identified upon gene array experiments with RNA isolated from sponges from the wound site in mouse with LED treatment. CONCLUSION: We believe that the use of NASA light-emitting diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the Defense Advanced Research Projects Agency (DARPA) and NASA Marshall Space Flight Center-SBIR Program.

Animals↗
PubMed1998

Flight crew fatigue I: objectives and methods.

In 1980, NASA-Ames Research Center, Moffett Field, CA, initiated a program to assess flight crew fatigue, determine its potential operational consequences, and provide practical countermeasure suggestions. To assess the extent of the problem, crewmembers were monitored before, during, and after commercial short-haul (fixed-wing and helicopter aircraft), overnight cargo, and long-haul operations. A total of 197 volunteers were studied on 94 trip patterns with 1299 flight segments and 2046 h of flying time. The present paper outlines the program and describes the common methodology used in these studies, which are then presented in detail in the four subsequent papers. The sixth paper offers a synthesis of this work, reviewing the major causes of flight crew fatigue and making specific suggestions about ways to manage it in different operations.

Aviation↗
PubMed1999

Nutrition and muscle loss in humans during spaceflight.

The protein loss in humans during spaceflight is partly due to a normal adaptive response to a decreased work load on the muscles involved in weight bearing. The process is mediated by changes in prostaglandin release, secondary to the decrease in tension on the affected muscles. On missions, where there is a high level of physical demands on the astronauts, there tends to be an energy deficit, which adds to the muscle protein loss and depletes the body fat reserves. While the adaptive response is a normal part of homeostasis, the additional protein loss from an energy deficit can, in the long run, have a negative effect on health and capability of humans to live and work in space and afterward return to Earth.

Animals↗