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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Study report on interfacing major physiological subsystem models: An approach for developing a whole-body algorithm

Using a whole body algorithm simulation model, a wide variety and large number of stresses as well as different stress levels were simulated including environmental disturbances, metabolic changes, and special experimental situations. Simulation of short term stresses resulted in simultaneous and integrated responses from the cardiovascular, respiratory, and thermoregulatory subsystems and the accuracy of a large number of responding variables was verified. The capability of simulating significantly longer responses was demonstrated by validating a four week bed rest study. In this case, the long term subsystem model was found to reproduce many experimentally observed changes in circulatory dynamics, body fluid-electrolyte regulation, and renal function. The value of systems analysis and the selected design approach for developing a whole body algorithm was demonstrated.

Fitzjerrell, D. G.↗
NASA NTRS1980

Simulated weightlessness - Effects on bioenergetic balance

As a prelude to a flight experiment, an attempt was made to separate energy requirements associated with gravity from all other metabolic needs. The biological effects of weightlessness were simulated by suspending animals in a harness so that antigravity muscles were not supporting the body. Twelve pairs of rats were allowed to adapt to wearing a harness for 5 d. Experimental animals were then suspended in harness for 7 d followed by recovery for 7 d. Control animals were harnessed but never suspended. Oxygen consumption, carbon dioxide production and rate of (C-14)O2 expiration from radio-labeled glucose were monitored on selected days. Food intake and body mass were recorded daily. Metabolic rate decreased in experimental animals during 7 d of suspension and returned to normal during recovery. Although some of the metabolic changes may have related to variation in food intake, simulated weightlessness appears to directly affect bioenergetic balance.

Jordan, J. P.↗
NASA NTRS1981

The effects of space flight on some rat liver enzymes regulating carbohydrate and lipid metabolism

The effects of space flight conditions on the activities of certain enzymes regulating carbohydrate and lipid metabolism in rat liver are investigated in an attempt to account for the losses in body weight observed during space flight despite preflight caloric consumption. Liver samples were analyzed for the activities of 32 cytosolic and microsomal enzymes as well as hepatic glycogen and individual fatty acid levels for ground control rats and rats flown on board the Cosmos 936 biosatellite under normal space flight conditions and in centrifuges which were sacrificed upon recovery or 25 days after recovery. Significant decreases in the activities of glycogen phosphorylase, alpha-glycerol phosphate acyl transferase, diglyceride acyl transferase, aconitase and 6-phosphogluconate dehydrogenase and an increase in palmitoyl CoA desaturase are found in the flight stationary relative to the flight contrifuged rats upon recovery, with all enzymes showing alterations returning to normal values 25 days postflight. The flight stationary group is also observed to be characterized by more than twice the amount of liver glycogen of the flight centrifuged group as well as a significant increase in the ratio of palmitic to palmitoleic acid. Results thus indicate metabolic changes which may be involved in the mechanism of weight loss during weightlessness, and demonstrate the equivalence of centrifugation during space flight to terrestrial gravity.

Abraham, S.↗
NASA NTRS1984

Metabolic alterations caused by suspension hypokinesia in leg muscles of rats

Metabolic changes on hypokinetic rats were measured. Two groups of animals were studied: (1) weight bearing control which were tail casted but allowed to walk on all four limbs, and (2) hypokinetic with no load bearing of the hindlimbs. The control and hypokinetic rats gained weight at a steady and similar rate over 6 days. Hypokinesia for 6 days led to significantly lower relative weights of the soleus, gastrocnemius and plantaris muscles. Hypokinesia did not effect the relative mass of the anterior tibialis or extensor digitorum longus (EDL) muscles.

Tischler, M. E.↗
NASA NTRS1991

Exercise thermoregulation - Possible effects of spaceflight

Changes in thermoregulation during spaceflight could result in an inability to tolerate ambient conditions or exercise tasks that were readily tolerated preflight. Weightlessness may alter heat production by changing metabolic rate, circadian rhythms of heat production, or work efficiency. It may impair heat loss by reducing convective and evaporative heat exchange. In addition, crewmembers may become less fit, less heat acclimated, hypohydrated, or have altered thermal sensitivity. Three scenarios are described: exercise conditioning in the mid deck, EVA, and emergency egress. Each scenario is discussed in terms of potential thermal challenges and possible consequences on crew performance.

Fortney, Suzanne M.↗
NASA NTRS1994

Drink composition and cycle-ergometer endurance in men: Carbohydrate, Na(+), osmolality

Cycle-ergometer endurance performance was determined in 5 untrained men (22-39 yr, 62.4-100.5 kg, 29-55 mL x min(exp -1) x kg(exp -1) peak oxygen uptake) after consuming Nothing (N) or two fluid formulations (10 mL x kg(exp -1), 555-998 mL). Performance 1 (P1), a multi-ionic-glucose rehydration drink, contains 55 mEq/L Na(exp +), 416 mg/dL citrate, 2,049 mg/dL glucose, and 365 mOsm/kgH2O. HyperAde (HA), a sodium chloride-citrate hyperhydration drink, contains 164 mEq/L Na(exp +), 854 mg/dL citrate, less than 0.5 mg/dL glucose, and 253 mOsm/kgH2O. Endurance at a load of 87-91 percent of peak VO2 was 30.50 +/- SE 3.44 min with HA; 24.55 +/- 1.09 min with P1 (p greater than 0.10 from HA); and 24.68 +/- 1.50 min with N (p less than 0.05 from HA). The attenuated endurance performance with P1 and N could not be attributed to differences in exercise metabolism, change or absolute level of rectal and mean skin temperature, or change in perceived exertion. The greater increase in resting plasma volume with HA, compared with P1 or N, probably contributed to the greater endurance with HA.

Greenleaf, J. E.↗
NASA NTRS2003

Spaceflight hardware for conducting plant growth experiments in space: the early years 1960-2000

The best strategy for supporting long-duration space missions is believed to be bioregenerative life support systems (BLSS). An integral part of a BLSS is a chamber supporting the growth of higher plants that would provide food, water, and atmosphere regeneration for the human crew. Such a chamber will have to be a complete plant growth system, capable of providing lighting, water, and nutrients to plants in microgravity. Other capabilities include temperature, humidity, and atmospheric gas composition controls. Many spaceflight experiments to date have utilized incomplete growth systems (typically having a hydration system but lacking lighting) to study tropic and metabolic changes in germinating seedlings and young plants. American, European, and Russian scientists have also developed a number of small complete plant growth systems for use in spaceflight research. Currently we are entering a new era of experimentation and hardware development as a result of long-term spaceflight opportunities available on the International Space Station. This is already impacting development of plant growth hardware. To take full advantage of these new opportunities and construct innovative systems, we must understand the results of past spaceflight experiments and the basic capabilities of the diverse plant growth systems that were used to conduct these experiments. The objective of this paper is to describe the most influential pieces of plant growth hardware that have been used for the purpose of conducting scientific experiments during the first 40 years of research. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Non-NASA Center↗
NASA NTRS1999

Effects of spaceflight conditions on fertilization and embryogenesis in the sea urchin Lytechinus pictus

Calcium loss and muscle atrophy are two of the main metabolic changes experienced by astronauts and crew members during exposure to microgravity in space. Calcium and cytoskeletal events were investigated within sea urchin embryos which were cultured in space under both microgravity and 1 g conditions. Embryos were fixed at time-points ranging from 3 h to 8 days after fertilization. Investigative emphasis was placed upon: (1) sperm-induced calcium-dependent exocytosis and cortical granule secretion, (2) membrane fusion of cortical granule and plasma membranes; (3) microfilament polymerization and microvilli elongation; and (5) embryonic development into morula, blastula, gastrula, and pluteus stages. For embryos cultured under microgravity conditions, the processes of cortical granule discharge, fusion of cortical granule membranes with the plasma membrane, elongation of microvilli and elevation of the fertilization coat were reduced in comparison with embryos cultured at 1 g in space and under normal conditions on Earth. Also, 4% of all cells undergoing division in microgravity showed abnormalities in the centrosome-centriole complex. These abnormalities were not observed within the 1 g flight and ground control specimens, indicating that significant alterations in sea urchin development processes occur under microgravity conditions. Copyright 1999 Academic Press.

STS-77 Shuttle Project↗
NASA NTRS1998

Fluid shear-induced mechanical signaling in MC3T3-E1 osteoblasts requires cytoskeleton-integrin interactions

Mechanical stimulation of bone induces new bone formation in vivo and increases the metabolic activity and gene expression of osteoblasts in culture. We investigated the role of the actin cytoskeleton and actin-membrane interactions in the transmission of mechanical signals leading to altered gene expression in cultured MC3T3-E1 osteoblasts. Application of fluid shear to osteoblasts caused reorganization of actin filaments into contractile stress fibers and involved recruitment of beta1-integrins and alpha-actinin to focal adhesions. Fluid shear also increased expression of two proteins linked to mechanotransduction in vivo, cyclooxygenase-2 (COX-2) and the early response gene product c-fos. Inhibition of actin stress fiber development by treatment of cells with cytochalasin D, by expression of a dominant negative form of the small GTPase Rho, or by microinjection into cells of a proteolytic fragment of alpha-actinin that inhibits alpha-actinin-mediated anchoring of actin filaments to integrins at the plasma membrane each blocked fluid-shear-induced gene expression in osteoblasts. We conclude that fluid shear-induced mechanical signaling in osteoblasts leads to increased expression of COX-2 and c-Fos through a mechanism that involves reorganization of the actin cytoskeleton. Thus Rho-mediated stress fiber formation and the alpha-actinin-dependent anchorage of stress fibers to integrins in focal adhesions may promote fluid shear-induced metabolic changes in bone cells.

Non-NASA Center↗
NASA NTRS1998

Spaceflight alters microtubules and increases apoptosis in human lymphocytes (Jurkat)

Alteration in cytoskeletal organization appears to underlie mechanisms of gravity sensitivity in space-flown cells. Human T lymphoblastoid cells (Jurkat) were flown on the Space Shuttle to test the hypothesis that growth responsiveness is associated with microtubule anomalies and mediated by apoptosis. Cell growth was stimulated in microgravity by increasing serum concentration. After 4 and 48 h, cells filtered from medium were fixed with formalin. Post-flight, confocal microscopy revealed diffuse, shortened microtubules extending from poorly defined microtubule organizing centers (MTOCs). In comparable ground controls, discrete microtubule filaments radiated from organized MTOCs and branched toward the cell membrane. At 4 h, 30% of flown, compared to 17% of ground, cells showed DNA condensation characteristic of apoptosis. Time-dependent increase of the apoptosis-associated Fas/ APO-1 protein in static flown, but not the in-flight 1 g centrifuged or ground controls, confirmed microgravity-associated apoptosis. By 48 h, ground cultures had increased by 40%. Flown populations did not increase, though some cells were cycling and actively metabolizing glucose. We conclude that cytoskeletal alteration, growth retardation, and metabolic changes in space-flown lymphocytes are concomitant with increased apoptosis and time-dependent elevation of Fas/APO-1 protein. We suggest that reduced growth response in lymphocytes during spaceflight is linked to apoptosis.

STS-76 Shuttle Project↗
NASA NTRS2009

Dietary Intake Can Predict and Protect Against Changes in Bone Metabolism during Spaceflight and Recovery (Pro K)

Bone loss is not only a well-documented effect of spaceflight on astronauts, but also a condition that affects millions of men and women on Earth each year. Many countermeasures aimed at preventing bone loss during spaceflight have been proposed, and many have been evaluated to some degree. To date, those showing potential have focused on either exercise or pharmacological interventions, but none have targeted dietary intake alone as a factor to predict or minimize bone loss during spaceflight. The "Dietary Intake Can Predict and Protect against Changes in Bone Metabolism during Spaceflight and Recovery" investigation ("Pro K") is one of the first inflight evaluations of a dietary countermeasure to lessen bone loss of astronauts. This protocol will test the hypothesis that the ratio of acid precursors to base precursors (specifically animal protein to potassium) in the diet can predict directional changes in bone mineral during spaceflight and recovery. The ratio of animal protein to potassium in the diet will be controlled for multiple short (4-day) periods before and during flight. Based on multiple sets of bed rest data, we hypothesize that a higher ratio of the intake of animal protein to the intake of potassium will yield higher concentrations of markers of bone resorption and urinary calcium excretion during flight and during recovery from bone mineral loss after long-duration spaceflight.

Smith, Scott M.↗
NASA NTRS1974

Microbial metabolism and dynamic changes in the electrical conductivity of soil solutions - A method for detecting extraterrestrial life

Experiments are reported which show that measuring metabolic activity in soil solutions by means of dynamic changes in electrical conductivity, water-soluble Ca, or water-soluble Mg is a feasible life detection method. The addition of 0.5% glucose solutions to 12 different air-dried soils always resulted in increases in all three of these parameters. The kinetics and magnitude of these changes for at least two and usually all three of the parameters over a 14-day period were clearly distinguishable from the changes in heat-sterilized controls or unsterilized controls without added glucose. In general, maximal values were achieved more rapidly under aerobic than under anaerobic incubation.

Silverman, M. P.↗
DOE OSTI2022

Overexpression of phospholipid: diacylglycerol acyltransferase in Brassica napus results in changes in lipid metabolism and oil accumulation

The regulation of lipid metabolism in oil seeds is still not fully understood and increasing our knowledge in this regard is of great economic, as well as intellectual, importance. Oilseed rape (Brassica napus) is a major global oil crop where increases in triacylglycerol (TAG) accumulation have been achieved by overexpression of relevant biosynthetic enzymes. In this study, we expressed Arabidopsis phospholipid: diacylglycerol acyltransferase (PDAT1), one of the two major TAG-forming plant enzymes in B. napus DH12075 to evaluate its effect on lipid metabolism in developing seeds and to estimate its flux control coefficient. Despite several-fold increase in PDAT activity, seeds of three independently generated PDAT transgenic events showed a small but consistent decrease in seed oil content and had altered fatty acid composition of phosphoglycerides and TAG, towards less unsaturation. Mass spectrometry imaging of seed sections confirmed the shift in lipid compositions and indicated that PDAT overexpression altered the distinct heterogeneous distributions of phosphatidylcholine (PC) molecular species. Similar, but less pronounced, changes in TAG molecular species distributions were observed. Our data indicate that PDAT exerts a small, negative, flux control on TAG biosynthesis and could have under-appreciated effects in fine-tuning of B. napus seed lipid composition in a tissue-specific manner. This has important implications for efforts to increase oil accumulation in similar crops.

Biochemistry & Molecular Biology↗
DOE OSTI2020

Large-scale proteomic analysis of Alzheimer’s disease brain and cerebrospinal fluid reveals early changes in energy metabolism associated with microglia and astrocyte activation

Our understanding of Alzheimer’s disease (AD) pathophysiology remains incomplete. Here, for this work, we used quantitative mass spectrometry and coexpression network analysis to conduct the largest proteomic study thus far on AD. A protein network module linked to sugar metabolism emerged as one of the modules most significantly associated with AD pathology and cognitive impairment. This module was enriched in AD genetic risk factors and in microglia and astrocyte protein markers associated with an anti-inflammatory state, suggesting that the biological functions it represents serve a protective role in AD. Proteins from this module were elevated in cerebrospinal fluid in early stages of the disease. In this study of >2,000 brains and nearly 400 cerebrospinal fluid samples by quantitative proteomics, we identify proteins and biological processes in AD brains that may serve as therapeutic targets and fluid biomarkers for the disease.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1975

Stress-induced changes in corticosteroid metabolism

Because plasma and urine corticosteroid concentrations are influenced by several factors in addition to adrenal cortex secretion, the effect of stress on all of these factors was determined in order to interpret the plasma and urine concentrations. Progress on the investigation is reported.

Tacker, M. M.↗
NASA NTRS1985

Possible mechanism for changes in glycogen metabolism in unloaded soleus muscle

Carbohydrate metabolism has been shown to be affected in a number of ways by different models of hypokinesia. In vivo glycogen levels in the soleus muscle are known to be increased by short-term denervation and harness suspension. In addition, exposure to 7 days of hypogravity also caused a dramatic increase in glycogen concentration in this muscle. The biochemical alterations caused by unloading that may bring about these increases in glycogen storage in the soleus were sought.

Henriksen, E. J.↗
NASA NTRS1985

Possible mechanism for changes in glycogen metabolism in unloaded soleus muscle

Carbohydrate metabolism has been shown to be affected in a number of ways by different models of hypokinesia. In vivo glycogen levels in the soleus muscle are known to be increased by short-term denervation and harness suspension. In addition, exposure to 7 days of hypogravity also caused a dramatic increase in glycogen concentration in this muscle. The biochemical alterations caused by unloading that may bring about these increases in glycogen storage in the soleus were sought.

Henriksen, E. J.↗