The Experts below are selected from a list of 14031 Experts worldwide ranked by ideXlab platform
Duane L. Pierson - One of the best experts on this subject based on the ideXlab platform.
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176 immune cell phenotypes and nk cell function in Astronauts and controls 5 months before a 6 month mission to the international space station
Brain Behavior and Immunity, 2014Co-Authors: Guillaume Spielmann, Duane L. Pierson, Austin B Bigley, Brian E Crucian, S Mehta, Hawley Kunz, Nadia H Agha, Emily C Lavoy, Richard J SimpsonAbstract:Human space exploration provides great technological, medical and academic advances to humanity, but also poses many threats to the health of the crew. Astronauts are subjected to a myriad of both physical and psychological stressors that may negatively affect the immune system and increase the risk of an adverse health event in flight. In this ongoing study, we compared immune cell phenotypes and NK-cell activity (NKCA) between Astronauts and controls 5-months before a 6-month mission to the International Space Station (ISS). Blood samples were taken from 6 Astronauts and 6 non-Astronaut controls and assayed for immune cell phenotypes and NKCA by flow cytometry. Astronauts had lower proportions and numbers of naive KLRG1−/CD28+ (p 0.05). We conclude that Astronauts display only small baseline differences in T-cell phenotype and NKCA compared to controls when assessed 5-months prior to launch. This study will continue to monitor immune function changes in these Astronauts and ground-based controls during and after a 6-month mission to the ISS.
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stress induced subclinical reactivation of varicella zoster virus in Astronauts
Journal of Medical Virology, 2004Co-Authors: Satish K Mehta, Randall J Cohrs, Bagher Forghani, Gary O Zerbe, Donald H Gilden, Duane L. PiersonAbstract:Varicella zoster virus (VZV) becomes latent in human ganglia after primary infection. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients, and patients with cancer and AIDS, correlating with a specific decline in cell-mediated immunity to the virus. VZV can also reactivate after surgical stress. The unexpected occurrence of thoracic zoster 2 days before space flight in a 47-year-old healthy Astronaut from a pool of 81 physically fit Astronauts prompted our search for VZV reactivation during times of stress to determine whether VZV can also reactivate after non-surgical stress. We examined total DNA extracted from 312 saliva samples of eight Astronauts before, during, and after space flight for VZV DNA by polymerase chain reaction: 112 samples were obtained 234-265 days before flight, 84 samples on days 2 through 13 of space flight, and 116 samples on days 1 through 15 after flight. Before space flight, only one of the 112 saliva samples from a single Astronaut was positive for VZV DNA. In contrast, during and after space flight, 61 of 200 (30%) saliva samples were positive in all eight Astronauts. No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These results indicate that VZV can reactivate subclinically in healthy individuals after non-surgical stress.
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stress induced subclinical reactivation of varicella zoster virus in Astronauts
Journal of Medical Virology, 2004Co-Authors: Satish K Mehta, Randall J Cohrs, Bagher Forghani, Gary O Zerbe, Donald H Gilden, Duane L. PiersonAbstract:After primary infection, varicella-zoster virus (VZV) becomes latent in ganglia. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients, and patients with cancer and AIDS, correlating with a specific decline in cell-mediated immunity to VZV. VZV can also reactivate after surgical stress. To determine whether VZV can also reactivate after acute non-surgical stress, we examined total DNA extracted from 312 saliva samples of eight Astronauts before, during and after space flight for VZV DNA by PCR: 112 samples were obtained 234 to 265 days before flight, 84 samples on days 2 through 13 of space flight, and 116 samples on days 1 through 15 after flight. Before space flight only one of the 112 saliva samples from a single Astronaut was positive for VZV DNA. In contrast, during and after space flight, 61 of 200 (30%) saliva samples were positive in all 8 Astronauts. No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These data indicate that VZV can reactivate subclinically in healthy individuals after acute stress.
Peter Paul De Deyn - One of the best experts on this subject based on the ideXlab platform.
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intracranial pressure induced optic nerve sheath response as a predictive biomarker for optic disc edema in Astronauts
Biomarkers in Medicine, 2017Co-Authors: Peter Wostyn, Peter Paul De DeynAbstract:A significant proportion of the Astronauts who spend extended periods in microgravity develop ophthalmic abnormalities. Understanding this syndrome, called visual impairment and intracranial pressure (VIIP), has become a high priority for National Aeronautics and Space Administration, especially in view of future long-duration missions (e.g., Mars missions). Moreover, to ensure selection of Astronaut candidates who will be able to complete long-duration missions with low risk of the VIIP syndrome, it is imperative to identify biomarkers for VIIP risk prediction. Here, we hypothesize that the optic nerve sheath response to alterations in intracranial pressure may be a potential predictive biomarker for optic disc edema in Astronauts. If confirmed, this biomarker could be used for preflight identification of Astronauts at risk for developing VIIP-associated optic disc edema.
Lailu Li - One of the best experts on this subject based on the ideXlab platform.
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Running Experimental Research of a Wire Driven Astronaut Rehabilitative Training Robot
IEEE Access, 2018Co-Authors: Lixun Zhang, Lailu LiAbstract:Keeping Astronauts physically healthy in the harsh space environment is a key to the successful execution of a space mission. Long-term space missions in the weightless environment, however, can result in space adaptation syndrome, which seriously affects Astronauts' health. To alleviate the adverse effects, this paper proposes a wire driven Astronaut rehabilitative training robot that simulates the characteristics of the gravity environment and load force on the Astronauts. The robot can realize multiple physical exercises including running, bench press, and deep squat. A dynamic model of the wire driven unit (WDU) was provided. On this basis, a hybrid force controller was designed to improve the precision and real-time performance of WDU. Furthermore, a dual-closed-loop control strategy was proposed to improve the loading precision of the robot. Running experimental results demonstrate that the robot can load force safely and reliably during the physical training, and the control strategies are effective.
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Force Control Strategy and Bench Press Experimental Research of a Cable Driven Astronaut Rehabilitative Training Robot
IEEE Access, 2017Co-Authors: Lixun Zhang, Lailu Li, Keyi Wang, Xize Jiang, Haoran JuAbstract:This paper presents a cable driven Astronaut rehabilitative training (ART) robot, which can provide Astronauts with multiple physical exercises including bench press, running, and deep squat to alleviate and resist the adverse effects induced by space adaptation syndrome. First, the modular reconfiguration of the ART driven by a cable is proposed to simulate the load characteristics of the gravity environment. Second, in order to improve the accuracy of the ART, the force control strategy is presented. The controller consists of two parts: high-level controller, which to calculate the desired cable tension and low-level controller, which to make each cable achieve the desired tension. Finally, to validate the effect of the ART, three (adult male) weight lifters were recruited to perform several bench press exercises with the barbell and ART. The analysis of the surface electromyography (sEMG) of triceps brachii and pectoralis major during real bench press and bench press simulated by the ART was conducted. The performance of the ART and the data of sEMG demonstrate the controller is effective and the ART can effectively assist Astronauts to carry out bench press exercises in space.
Satish K Mehta - One of the best experts on this subject based on the ideXlab platform.
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investigation of spaceflight induced changes to Astronaut microbiomes
Frontiers in Microbiology, 2021Co-Authors: Michael Morrison, Satish K Mehta, James B Thissen, Fathi Karouia, Camilla Urbaniak, Kasthuri Venkateswaran, David J Smith, Crystal JaingAbstract:The International Space Station (ISS) is a uniquely enclosed environment that has been continuously occupied for the last two decades. Throughout its operation, protecting the health of the Astronauts on-board has been a high priority. The human microbiome plays a significant role in maintaining human health, and disruptions in the microbiome have been linked to various diseases. To evaluate the effects of spaceflight on the human microbiome, body swabs and saliva samples were collected from four ISS Astronauts on consecutive expeditions. Astronaut samples were analyzed using shotgun metagenomic sequencing and microarrays to characterize the microbial biodiversity before, during, and after the Astronauts' time onboard the ISS. Samples were evaluated at an individual and population level to identify changes in microbial diversity and abundance. No significant changes in the number or relative abundance of taxa were observed between collection time points when samples from all four Astronauts were analyzed together. When the Astronauts' saliva samples were analyzed individually, the saliva samples of some Astronauts showed significant changes in the relative abundance of taxa during and after spaceflight. The relative abundance of Prevotella in saliva samples increased during two Astronauts' time onboard the ISS while the relative abundance of other commensal taxa such as Neisseria, Rothia, and Haemophilus decreased. The abundance of some antimicrobial resistance genes within the saliva samples also showed significant changes. Most notably, elfamycin resistance gene significantly increased in all four Astronauts post-flight and a CfxA6 beta-lactam marker significantly increased during spaceflight but returned to normal levels post-flight. The combination of both shotgun metagenomic sequencing and microarrays showed the benefit of both technologies in monitoring microbes on board the ISS. There were some changes in each Astronaut's microbiome during spaceflight, but these changes were not universal for all four Astronauts. Two antimicrobial resistance gene markers did show a significant change in abundance in the saliva samples of all four Astronauts across their collection times. These results provide insight for future ISS microbial monitoring studies and targets for antimicrobial resistance screenings.
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stress induced subclinical reactivation of varicella zoster virus in Astronauts
Journal of Medical Virology, 2004Co-Authors: Satish K Mehta, Randall J Cohrs, Bagher Forghani, Gary O Zerbe, Donald H Gilden, Duane L. PiersonAbstract:Varicella zoster virus (VZV) becomes latent in human ganglia after primary infection. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients, and patients with cancer and AIDS, correlating with a specific decline in cell-mediated immunity to the virus. VZV can also reactivate after surgical stress. The unexpected occurrence of thoracic zoster 2 days before space flight in a 47-year-old healthy Astronaut from a pool of 81 physically fit Astronauts prompted our search for VZV reactivation during times of stress to determine whether VZV can also reactivate after non-surgical stress. We examined total DNA extracted from 312 saliva samples of eight Astronauts before, during, and after space flight for VZV DNA by polymerase chain reaction: 112 samples were obtained 234-265 days before flight, 84 samples on days 2 through 13 of space flight, and 116 samples on days 1 through 15 after flight. Before space flight, only one of the 112 saliva samples from a single Astronaut was positive for VZV DNA. In contrast, during and after space flight, 61 of 200 (30%) saliva samples were positive in all eight Astronauts. No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These results indicate that VZV can reactivate subclinically in healthy individuals after non-surgical stress.
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stress induced subclinical reactivation of varicella zoster virus in Astronauts
Journal of Medical Virology, 2004Co-Authors: Satish K Mehta, Randall J Cohrs, Bagher Forghani, Gary O Zerbe, Donald H Gilden, Duane L. PiersonAbstract:After primary infection, varicella-zoster virus (VZV) becomes latent in ganglia. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients, and patients with cancer and AIDS, correlating with a specific decline in cell-mediated immunity to VZV. VZV can also reactivate after surgical stress. To determine whether VZV can also reactivate after acute non-surgical stress, we examined total DNA extracted from 312 saliva samples of eight Astronauts before, during and after space flight for VZV DNA by PCR: 112 samples were obtained 234 to 265 days before flight, 84 samples on days 2 through 13 of space flight, and 116 samples on days 1 through 15 after flight. Before space flight only one of the 112 saliva samples from a single Astronaut was positive for VZV DNA. In contrast, during and after space flight, 61 of 200 (30%) saliva samples were positive in all 8 Astronauts. No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These data indicate that VZV can reactivate subclinically in healthy individuals after acute stress.
Christian Otto - One of the best experts on this subject based on the ideXlab platform.
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optical coherence tomography analysis of the optic nerve head and surrounding structures in long duration international space station Astronauts
JAMA Ophthalmology, 2018Co-Authors: Nimesh B Patel, Charles Robert Gibson, Anastas Pass, Sara Mason, Christian OttoAbstract:Importance After long-duration spaceflight, morphological changes in the optic nerve head (ONH) and surrounding tissues have been reported. Objective To develop methods to quantify ONH and surrounding tissue changes using preflight and postflight optical coherence tomographic scans of the ONH region. Design, Setting, and Participants Two separate analyses were done on retrospective data, with the first comparing a preflight group with a control group, followed by preflight to postflight analysis. All Astronaut data were collected on the same instrument and maintained by the National Aeronautics and Space Administration (NASA) Lifetime Surveillance of Astronaut Health. Control data were all collected at the University of Houston. Participants were 15 Astronauts who had previously been on an approximately 6-month long-duration mission and had associated preflight and postflight ONH scans. The control group consisted of 43 individuals with no history of ocular pathology or microgravity exposure. Development of algorithms and data analysis were performed between 2012 and 2015. Main Outcomes and Measures The optical coherence tomography data were analyzed using custom MATLAB programs (MathWorks) in which the Bruch membrane opening (BMO) was manually delineated and used as a reference for all morphological measures. The retinal pigment epithelium (RPE) position 2 mm from the center of the BMO was used to calculate the BMO height. Global and quadrant total retinal thickness and retinal nerve fiber layer (RNFL) thickness were calculated for elliptical annular regions referenced to the BMO. The standard circumpapillary circular scan was used to quantify RNFL and choroidal thickness. Results Among 15 Astronauts (mean [SD] age at preflight evaluation, 48.7 [4.0] years) in this retrospective study, the BMO was recessed in preflight Astronauts compared with healthy controls and deepened after long-duration microgravity exposure (median change, −9.9 μm; 95% CI of difference, −16.3 to 3.7 μm; P = .03). After long-duration missions, there was an increase in total retinal thickness to 1000 μm and RNFL to 500 μm from the BMO. Circumpapillary RNFL thickness increased by a median of 2.9 μm (95% CI of difference, 1.1-4.4 μm; P P = .66). Conclusions and Relevance After long-duration microgravity exposure, there are disc edema–like changes in the morphology of the ONH and surrounding tissue. The methods developed to analyze the ONH and surrounding tissue can be useful for assessing longitudinal changes and countermeasures in Astronauts, as well as potentially for terrestrial disc edema causes.
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Astronaut preflight cardiovascular variables associated with vascular compliance are highly correlated with post flight eye outcome measures in the visual impairment intracranial pressure viip syndrome following long duration spaceflight
2015Co-Authors: Christian Otto, Robert PloutzsnyderAbstract:The detection of the first VIIP case occurred in 2005, and adequate eye outcome measures were available for 31 (67.4%) of the 46 long duration US crewmembers who had flown on the ISS since its first crewed mission in 2000. Therefore, this analysis is limited to a subgroup (22 males and 9 females). A "cardiovascular profile" for each Astronaut was compiled by examining twelve individual parameters; eleven of these were preflight variables: systolic blood pressure, pulse pressure, body mass index, percentage body fat, LDL, HDL, triglycerides, use of antilipid medication, fasting serum glucose, and maximal oxygen uptake in ml/kg. Each of these variables was averaged across three preflight annual physical exams. Astronaut age prior to the long duration mission, and inflight salt intake was also included in the analysis. The group of cardiovascular variables for each crew member was compared with seven VIIP eye outcome variables collected during the immediate postflight period: anterior-posterior axial length of the globe measured by ultrasound and optical biometry; optic nerve sheath diameter, optic nerve diameter, and optic nerve to sheath ratio each measured by ultrasound and magnetic resonance imaging (MRI), intraocular pressure (IOP), change in manifest refraction, mean retinal nerve fiber layer (RNFL) on optical coherence tomography (OCT), and RNFL of the inferior and superior retinal quadrants. Since most of the VIIP eye outcome measures were added sequentially beginning in 2005, as knowledge of the syndrome improved, data were unavailable for 22.0% of the outcome measurements. To address the missing data, we employed multivariate multiple imputation techniques with predictive mean matching methods to accumulate 200 separate imputed datasets for analysis. We were able to impute data for the 22.0% of missing VIIP eye outcomes. We then applied Rubin's rules for collapsing the statistical results across our 200 multiply imputed data sets to assess the canonical correlation between the eye outcomes and the twelve Astronaut cardiovascular variables available for all 31 subjects. Results: A highly significant canonical correlation was observed among the canonical solutions (p F = 0.00001). Overall, female Astronauts demonstrated a significantly healthier cardiovascular status. Individually, the female Astronauts had significantly healthier profiles on seven of twelve cardiovascular variables than the men (p values ranging from <0.0001 to <0.05). Male Astronauts did not demonstrate significantly healthier values on any of the twelve cardiovascular variables measured
