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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Test of the antiorthostatic suspension model on mice - Effects on the inflammatory cell response

The antiorthostatic suspension model was tested for use as a 1G model to study the effects of factors that will be encountered during space travel on inflammation. No differences were found in inflammatory cells induced in antiorthostatically suspended mice. However, the superoxide response (used for oxidative killing of bacteria such as S. aureus) was impaired in antiorthostatically oriented mice compared to control mice. Elevated corticosterone levels were found in antiorthostatically suspended mice, indicating that stress may be a factor in the model. If the stress factor of the model correlates with the physiological stress of space flight, antiorthostatic suspension may be an acceptable model for studying inflammatory responses in mice.

Rosenkrans, Charles F., Jr.↗
DOE OSTI2022

Morphine and high-fat diet differentially alter the gut microbiota composition and metabolic function in lean versus obese mice

There are known associations between opioids, obesity, and the gut microbiome, but the molecular connection/mediation of these relationships is not understood. To better clarify the interplay of physiological, genetic, and microbial factors, this study investigated the microbiome and host inflammatory responses to chronic opioid administration in genetically obese, diet-induced obese, and lean mice. Samples of feces, urine, colon tissue, and plasma were analyzed using targeted LC-MS/MS quantification of metabolites, immunoassays of inflammatory cytokine levels, genome-resolved metagenomics, and metaproteomics. Genetic obesity, diet-induced obesity, and morphine treatment in lean mice each showed increases in distinct inflammatory cytokines. Metagenomic assembly and binning uncovered over 400 novel gut bacterial genomes and species. Morphine administration impacted the microbiome’s composition and function, with the strongest effect observed in lean mice. This microbiome effect was less pronounced than either diet or genetically driven obesity. Based on inferred microbial physiology from the metaproteome datasets, a high-fat diet transitioned constituent microbes away from harvesting diet-derived nutrients and towards nutrients present in the host mucosal layer. Considered together, these results identified novel host-dependent phenotypes, differentiated the effects of genetic obesity versus diet induced obesity on gut microbiome composition and function, and showed that chronic morphine administration altered the gut microbiome.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

The uncertain role of rising atmospheric CO 2 on global plant transpiration

As CO 2 concentration in the atmosphere rises, there is a need for improved physical understanding of its impact on global plant transpiration. This knowledge gap poses a major hurdle in robustly projecting changes in the global hydrologic cycle. For this reason, here we review the different processes by which atmospheric CO 2 concentration affects plant transpiration, the several uncertainties related to the complex physiological and radiative processes involved, and the knowledge gaps which need to be filled in order to improve predictions of plant transpiration. Additionally, although there is a high degree of certainty that rising CO 2 will impact plant transpiration, the exact nature of this impact remains unclear due to complex interactions between CO 2 and climate, and key aspects of plant morphology and physiology. The interplay between these factors has substantial consequences not only for future climate and global vegetation, but also for water availability needed for sustaining the productivity of terrestrial ecosystems. Future changes in global plant transpiration in response to enhanced CO 2 are expected to be driven by water availability, atmospheric evaporative demand, plant physiological processes, emergent plant disturbances related to increasing temperatures, and the modification of plant physiology and coverage. Considering the universal sensitivity of natural and agricultural systems to terrestrial water availability we argue that reliable future projections of transpiration is an issue of the highest priority, which can only be achieved by integrating monitoring and modeling efforts to improve the representation of CO 2 effects on plant transpiration in the next generation of earth system models.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1994

Human cardiovascular response to sympathomimetic agents during head-down bed rest: the effect of dietary sodium

Changes in sympathoadrenal function and cardiovascular deconditioning have long been recognized as a feature of the physiological adaptation to microgravity. The deconditioning process, coupled with altered hydration status, is thought to significantly contribute to orthostatic intolerance upon return to Earth gravity. The cardiovascular response to stimulation by sympathomimetic agents before, during, and after exposure to simulated microgravity was determined in healthy volunteers equilibrated on normal or high sodium diets in order to further the understanding of the deconditioning process.

NASA Discipline Number 18-10↗
NASA NTRS2007

Radiative and Physiological Effects of Increased CO2. How does this interaction affect Climate in the Mediterranean Region?

the radiative and physiological effects of doubled atmospheric carbon dioxide concentration (CO2) on climate are described using climate simulations. When CO2 was increased for vegetation only assuming no radiative effect, the response was a decrease in stomatal conductance followed by a temperature increase. This temperature increase was stronger when the vegetation physiological down-regulation was allowed in the model. The radiative forcing alone did not affect the global mean photosynthesis, however, some stimulation was observed in cold places. The interactions between the physiological and the radiative effects of doubled CO2 are not linearly additive and when acting together they tend to reduce the warming in the Mediterranean region.

Bounoua, Lahouari↗
NASA NTRSDate not supplied

Preliminary Design of an 'Autonomous Medical Response Agent' Interface Prototype for Long Duration Spaceflight

Major challenges for astronauts in future long-duration exploration missions (LDEMs) will be that crewmembers are not expected to be medical professionals, may be under high workload and stress, are facing physiological challenges caused by spaceflight, and will have limited, delayed voice communications with medical support from Earth. An autonomous medical response agent (AMRA) is envisioned to help astronauts address medical complaints, develop a differential diagnosis, and guide self-treatment until a healthy state is restored. AMRA develops a process of personalized diagnosis and treatment through a Bayesian predictive control system that recommends therapeutic control actions including diagnostic tests and treatments to crewmembers (Menon, 2020). The Human Computer Interaction (HCI) lab from NASA Ames Research Center’s Human Systems Integration Division (Code TH) has collaborated with Nahlia Inc in human-centered design augmentation research for AMRA. The project, titled Design of ‘Autonomous Medical Response Agent Interface Prototype for Long Duration Spaceflight, has been funded by the Translational Research Institute for Space Health (TRISH) and introduces an interactive user-interface prototype that guides astronauts through self-diagnosis, treatment, and rehabilitation while communicating with remote specialists in ground support (most notably a patient’s flight surgeon). Our project develops the interaction design for the crewmember using AMRA through user research, iterative design, and usability testing to evaluate the user interface and workflow designed. The interface design deliverable for this project, titled AMRA Aggregate Information Display (AMRA AID) is an integrated information display system for comprehensive autonomous medical guidance, diagnosis, and treatment of in-flight medical conditions experienced by crewmembers. AMRA AID demonstrates how we might ensure crew autonomy, increase the crew’s medical capabilities, and decrease cognitive burden within a front-end user interface. AMRA AID refrains from relying on input from ground or mission control for self-treatment of medical issues—though ground awareness and communication with ground is maintained as a means of ensuring trust between mission control and crew. AMRA AID demonstrates how the crew’s on-board medical system might integrate with information from vehicle monitoring and crew schedule, without assuming causal relationships. AMRA AID’s comprehensive view enables efficient information access for both crew and ground support, reducing cognitive burden in the event of an unplanned or emergency medical incident and enabling informed analytical decisions to be made based on both crew and vehicle health. Human-centered design augmentation advanced within the prototype included: enhanced workflow and treatment guidance for two medical scenarios for a non-specialist user base with various levels of medical training, interaction design which considered speech (conversational user interface) elements and on-screen interactions to be developed in future iterations of the project, communication design and functional requirements relevant to self-care versus caring for another astronaut, as well as user testing of the prototype with an international space medical community. This project arrives at critical findings regarding usability needs, communication requirements, and integrated information requirements for a future technology interface functioning to increase confidence between ground support and LDEM crewmembers.

TRISH↗
NASA NTRS2002

Aging attenuates the vestibulosympathetic reflex in humans

BACKGROUND: The vestibular system contributes to sympathetic activation by engagement of the otolith organs. However, there is a significant loss of vestibular function with aging. Therefore, the purpose of the present study was to determine if young and older individuals differ in their cardiovascular and sympathetic responses to otolithic stimulation (ie, head-down rotation, HDR). We hypothesized that responses to otolithic stimulation would be attenuated in older adults because of morphological and physiological alterations that occur in the vestibular system with aging. METHODS AND RESULTS: Arterial blood pressure, heart rate, muscle sympathetic nerve activity (MSNA), and head rotation were measured during HDR in 11 young (26 +/- 1 years) and 11 older (64 +/- 1 years) subjects in the prone posture. Five older subjects performed head rotation (chin to chest) in the lateral decubitus position, which simulates HDR but does not alter afferent inputs from the vestibular system. MSNA responses to HDR were significantly attenuated in older as compared with young subjects (P<0.01). MSNA increased in the older subjects by only 12 +/- 5% as compared with 85 +/- 16% in the young. Furthermore, HDR elicited significant reductions in mean arterial blood pressure in older (Delta-6 +/- 1 mm Hg; P<0.01) but not young subjects (Delta1 +/- 1 mm Hg). In contrast to HDR, head rotation performed in the lateral decubitus position did not elicit hypotension. MSNA responses to baroreceptor unloading and the cold pressor test were not different between the age groups. CONCLUSIONS: These data indicate that aging attenuates the vestibulosympathetic reflex in humans and may contribute to the increased prevalence of orthostatic hypotension with age.

NASA Discipline Neuroscience↗
NASA NTRS1975

Physiological and biochemical characteristics of adrenergic receptors and pathways in brown adipocytes

Mechanisms involved in the thermogenic response of brown adipose tissue (BAT) to sympathetic nervous stimulation (e.g., by cold exposure) and to norepinephrine (NE) release are investigated. Three effects appear to play a role in the increased oxygen consumption (and heat production) of the adipocytes: increased membrane permeability, activation of the beta-adrenergic pathway, and enhancement of Na(+)/K(+) membrane pump activity. Increased passive influx of Na(+) and efflux of K(+) due to greater permeability raise the energy demands of the Na/K pump; the pump is also stimulated by increased cyclic AMP synthesis resulting from activation by NE of membrane-bound adenyl cyclase. Studies with inhibitors such as propanolol, phentolamine, and ouabain support this hypothesis.

Horwitz, B. A.↗
NASA NTRSDate not supplied

The Integrated Impact of Diet on Human Immune Response, the Gut Microbiota, and Nutritional Status During Adaptation to Spaceflight

Long-duration spaceflight impacts human physiology, including well documented immune system dysregulation. Diet, the microbiome, and immune system function are interlinked, but diet is the only one of these factors that we have the ability to easily, and significantly, alter on Earth or during flight. As we better understand dietary impacts on physiology, we may then improve the spaceflight diet to improve crew health and potentially reduce spaceflight-associated physiological decrements. Increasing the consumption of fruits and vegetables and bioactive compounds (e.g., omega-3 fatty acids, lycopene, flavonoids) and therefore enhancing overall nutritional intake from the nominal shelf-stable, fully-processed, space food system is expected to serve as a countermeasure to detrimental impacts to human physiology, including dysregulation in immunological profiles, the taxonomic profile of the gut microbiota, and nutritional status during spaceflight. In this study, first we sought to determine the effect of the nominal shelf-stable spaceflight diet compared to an "enhanced" shelf-stable spaceflight diet on human biochemistry, immunology, and the microbiome in a ground-based, simulated space mission. The ground analog portion of this study was conducted in the NASA Human Exploration Research Analog (HERA) Campaign 4 missions, which consisted of four 45-day missions with closed chamber confinement and realistic mission simulation to study effects on crew health and performance. As reported previously, analyses indicate beneficial associations between diet and markers of nutritional status, stress, the microbiome, and cognitive performance. Intake and beneficial associations varied by subject. This data will be used as a ground-based control for spaceflight, where the spaceflight environment (e.g., radiation, microgravity) will have additional impacts and the potential to evaluate effects of the diet will be greater. The second phase of this study is to occur on the International Space Station, where it is currently being implemented. The test plan is similar to that used in the HERA missions. The enhanced diet is intended to provide 25% of the crews’ diet with foods rich in omega-3 fatty acids, lycopene, and flavonoids, along with more fruits and vegetables in general (the other 75% of the diet will be obtained from standard and crew preference items available on the ISS). Biological samples (blood, urine, stool, and saliva) are being collected from participants at selected time points before, during, and after the mission. Data collection also includes dietary intake recording and body mass measurement. Currently, 6 of 9 planned astronauts have completed data collection. Analysis of immune markers, latent herpes virus reactivation, the taxonomic and metatranscriptomic profile of the gut microbiome, and nutritional status biomarkers and biochemical metabolites will occur in batch to minimize sample handling variations. Mixed models statistical analyses will be used, incorporating random effects to account for repeated measures within individuals to assess the impact of diet on physiological outcomes. We expect this study to provide evidence of beneficial impact of this enhanced diet on crew health and adaptation to spaceflight. These data will aid in evidence-based mass-risk trades for food system design and development of targeted dietary interventions for future exploration-class space missions.

Grace L. Douglas↗
NASA NTRS1994

Hemodynamic Responses to Head and Neck Cooling

Personal thermoregulatory systems which provide head and neck cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objective of this study was to measure the scalp temperature and circulatory responses during use of one commercially available thermal control system. The Life Support Systems, Inc. Mark VII portable cooling system and a liquid cooling helmet were used in this study. Two EEG electrodes and one skin temperature transducer were placed on the anterior midline of the scalp to measure the scalp blood and temperature. Blood flow was measured using a bipolar impedance rheograph. Ten subjects, seated in an upright position at normal room temperature, were tested at high, medium, moderate, moderate-low and low coolant temperatures. Scalp blood flow was recorded continuously using a computer data acquisition system with a sampling frequency of 200 Hz. Scalp temperature and cooling helmet Inlet temperature was logged periodically during the test period. This study quantifies the effect of head cooling upon scalp temperature and blood flow. These data may also be used to select operational specifications of the head cooling system for biomedical applications such as the treatment of migraine headaches, scalp cooling during chemotherapy, and cooling of multiple sclerosis patients.

Ku, Yu-Tsuan E.↗
DOE OSTI2023

Elucidating regulatory processes of intense physical activity by multi-omics analysis

Abstract Background Physiological and biochemical processes across tissues of the body are regulated in response to the high demands of intense physical activity in several occupations, such as firefighting, law enforcement, military, and sports. A better understanding of such processes can ultimately help improve human performance and prevent illnesses in the work environment. Methods To study regulatory processes in intense physical activity simulating real-life conditions, we performed a multi-omics analysis of three biofluids (blood plasma, urine, and saliva) collected from 11 wildland firefighters before and after a 45 min, intense exercise regimen. Omics profiles post- versus pre-exercise were compared by Student’s t -test followed by pathway analysis and comparison between the different omics modalities. Results Our multi-omics analysis identified and quantified 3835 proteins, 730 lipids and 182 metabolites combining the 3 different types of samples. The blood plasma analysis revealed signatures of tissue damage and acute repair response accompanied by enhanced carbon metabolism to meet energy demands. The urine analysis showed a strong, concomitant regulation of 6 out of 8 identified proteins from the renin-angiotensin system supporting increased excretion of catabolites, reabsorption of nutrients and maintenance of fluid balance. In saliva, we observed a decrease in 3 pro-inflammatory cytokines and an increase in 8 antimicrobial peptides. A systematic literature review identified 6 papers that support an altered susceptibility to respiratory infection. Conclusion This study shows simultaneous regulatory signatures in biofluids indicative of homeostatic maintenance during intense physical activity with possible effects on increased infection susceptibility, suggesting that caution against respiratory diseases could benefit workers on highly physical demanding jobs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

U.S. Department of Energy Free-Air CO 2 Enrichment Experiments: FACE Results, Lessons, and Legacy

In the 1970s, growing concern about potential long-range consequences of carbon dioxide (CO 2 ) emissions from the combustion of fossil fuels prompted the U.S. Department of Energy (DOE) to begin developing a CO 2 research program. The goal was to obtain the scientific information needed to reduce uncertainty and develop a knowledgebase for decision-making. At its start in 1980, this program had three components: the global carbon cycle, climate effects, and vegetation effects. The vegetation effects component recognized that increased atmospheric CO 2 could be a potential benefit to vegetation and crops because CO 2 is an essential resource for plant growth. In addition to increasing crop yield, program developers and researchers recognized that this fertilizer effect could also result in greater storage of fossil fuel CO 2 by forests. Initial experiments were small in scale and scope and focused on the photosynthesis, physiology, and water use of crop plants, but the focus shifted toward responses of plants in natural systems, as needed for connections to the global carbon cycle. Program research investigated CO 2 interactions with other environmental variables, emphasizing field research whenever possible and recognizing that exposure to elevated CO 2 concentrations under realistic field conditions should lead to better predictions of plant response. Whole-ecosystem field experiments were instituted in low-stature ecosystems, but experiments to address forest responses necessarily relied on tree seedlings or saplings in open-top chambers (OTCs) and not within intact forest ecosystems. The need for larger-scale, longer-duration experiments in each of the world’s six major biomes (tundra, boreal forest, temperate forest, tropical forest, grassland, and desert) became clear, and for these experiments, free-air CO 2 exposure facilities were necessary. This report summarizes the objectives and main results of DOE-sponsored experiments employing such facilities, along with the outcomes from research on ecosystem responses using field chambers (see Fig. ES.1, p. x). Additionally, this report highlights the many successes of DOE CO 2 enrichment studies and considers the lessons learned that can be used to guide future initiatives.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1984

On the measurement of pilot perceptual workload - A comparison of assessment techniques addressing sensitivity and intrusion issues

A flight simulator-based study was conducted to examine fourteen distinct mental workload estimation measures, including opinion, secondary task, physiological, and primary task measures. Both the relative sensitivity of the measures to changes in mental workload and the differential intrusion of the changes on primary task performance were assessed. The flight task was varied in difficulty by manipulation of the presentation rate and complexity of a hazard-perception task that required each of 48 licensed pilots to rely heavily on their perceptual abilities. Three rating scales (Modified Cooper-Harper, Multi-descriptor, and Workload-Compensation-Interference/Technical Effectiveness), two secondary task measures (time estimation and tapping regularity), one physiological measure (respiration frequency), and one primary task measure (danger-condition response time) were reliable indicants of workload changes. Recommendations for applying the workload measures are presented.

Casali, J. G.↗
NASA NTRS1990

Intrapericardial denervation - Radial artery blood flow and heart rate responses to LBNP

The effects of intrapericardial denervation on the radial artery blood flow velocity (RABFV) and heart rate (HR) responses to LBNP in rhesus monkeys were investigated by measuring the RABFV transcutaneously by a continuous-wave Doppler ultrasonic flowmeter in order to derive an index of forearm blood flow response to low (0 to -20 mm Hg) and high (0 to -60 mm Hg) ramp exposures during supine LBNP. Four of the eight subjects were subjected to efferent and afferent cardiac denervation. It was found that, during low levels of LBNP, monkeys with cardiac denervation exhibited no cardiopulmonary baroreceptor-mediated change in the RABFV or HR, unlike the intact animals, which showed steady decreases in RABFV during both high- and low-pressure protocols. It is suggested that forearm blood flow and HR responses to low-level LBNP, along with pharmacological challenge, are viable physiological tests for verifying the completeness of atrial and cardiopulmonary baroreceptor denervation.

Mckeever, Kenneth H.↗
NASA NTRS1993

Physics, chemistry and pulmonary sequelae of thermodegradation events in long-mission space flight

An event in which electronic insulation consisting of polytetrafluoroethylene undergoes thermodegradation on the Space Station Freedom is considered experimentally and theoretically from the initial chemistry and convective transport through pulmonary deposition in humans. The low-gravity enviroment impacts various stages of event simulation. Vapor-phase and particulate thermodegradation products were considered as potential spacecraft contaminants. A potential pathway for the production of ultrafine particles was identified. Different approaches to the simulation and prediction of contaminant transport were studied and used to predict the distribution of generic vapor-phase products in a Space Station model. A lung transport model was used to assess the pulmonary distribution of inhaled particles, and, finally, the impact of adaptation to low gravity on the human response to this inhalation risk was explored on the basis of known physiological modifications of the immune, endocrine, musculoskeletal and pulmonary systems that accompany space flight.

Todd, Paul↗
NASA NTRS1989

Effects of restricted feeding schedules on circadian organization in squirrel monkeys

Free running circadian rhythms of motor activity, food-motivated lever-pressing, and either drinking (N = 7) or body temperature (N = 3) were recorded from 10 squirrel monkeys maintained in constant illumination with unlimited access to food. Food availability was then restricted to a single unsignaled 3-hour interval each day. The feeding schedule failed to entrain the activity rhythms of 8 monkeys, which continued to free-run. Drinking was almost completely synchronized by the schedule, while body temperature showed a feeding-induced rise superimposed on a free-running rhythm. Nonreinforced lever-pressing showed both a free-running component and a 24-hour component that anticipated the time of feeding. At the termination of the schedule, all recorded variables showed free-running rhythms, but in 3 animals the initial phase of the postschedule rhythms was advanced by several hours, suggesting relative coordination. Of the remaining 2 animals, one exhibited stable entrainment of all 3 recorded rhythms, while the other appeared to entrain temporarily to the feeding schedule. These results indicate that restricted feeding schedules are only a weak zeitgeber for the circadian pacemaker generating free-running rhythms in the squirrel monkey. Such schedules, however, may entrain a separate circadian system responsible for the timing of food-anticipatory changes in behavior and physiology.

Non-NASA Center↗
NASA NTRS2005

Elastic model for crimped collagen fibrils

A physiologic constitutive expression is presented in algorithmic format for the nonlinear elastic response of wavy collagen fibrils found in soft connective tissues. The model is based on the observation that crimped fibrils in a fascicle have a three-dimensional structure at the micron scale that we approximate as a helical spring. The symmetry of this wave form allows the force/displacement relationship derived from Castigliano's theorem to be solved in closed form: all integrals become analytic. Model predictions are in good agreement with experimental observations for mitral-valve chordae tendinece.

Evaluation Studies↗
NASA NTRS2009

Right Ventricular Tissue Doppler in Space Flight

Tissue Doppler (TD) registers movement of a given sample of cardiac tissue throughout the cardiac cycle. TD spectra of the right ventricle (RV) were obtained from a long-duration ISS crewmember as a portion of an ongoing experiment ("Braslet" test objective). To our knowledge, this is the first report of RV TD conducted in space flight, and the data represent reproducibility and fidelity of this application in space and serve as the first "space normal" data set. Methods RV TD was performed by astronaut scientists remotely guided by an ultrasound expert from Mission Control Center, Houston, TX. In four of the subjects, RV TD was acquired from the free wall near the tricuspid annulus in two separate sessions 4 to 7 days apart. A fifth subject had only one session. All digital DICOM frames were exported for off-line analysis. Systolic (S ), early diastolic (E ) and late diastolic (A ) velocities were measured. RV Tei-index was calculated using diastolic and systolic time intervals as a combined measure of myocardial performance. Results and Discussion The mean values from the first 4 subjects (8 sessions) were used as the on-orbit reference data, and subject 5 was considered as a hypothetical patient for comparison (see Table). The greatest difference was in the early diastolic A (31 %) yet the standard deviation (a) for A amongst the reference subjects was 2.25 (mean = 16.02). Of interest is the Tei index, a simple and feasible indicator of overall ventricular function; it was similar amongst all the subjects. The late diastolic A seems to compensate for the variance in E . Normal Tei index for the RV is < 0.3, yet our data show all but one subject consistently above this level, notwithstanding their nominal responses to daily exercise in microgravity. These data remind us that the physiology of RV preload in altered gravity environments is still not completely understood.

Hamilton, Douglas R.↗