The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Duane L. Pierson - One of the best experts on this subject based on the ideXlab platform.

  • latent virus reactivation in astronauts on the international Space station
    NPJ microgravity, 2017
    Co-Authors: Satish K Mehta, Alan H. Feiveson, Mark L Laudenslager, Raymond P Stowe, Brian E Crucian, Clarence Sams, Duane L. Pierson
    Abstract:

    Reactivation of latent herpes viruses was measured in 23 astronauts (18 male and 5 female) before, during, and after long-duration (up to 180 days) Spaceflight onboard the international Space station . Twenty age-matched and sex-matched healthy ground-based subjects were included as a control group. Blood, urine, and saliva samples were collected before, during, and after Spaceflight. Saliva was analyzed for Epstein–Barr virus, varicella-zoster virus, and herpes simplex virus type 1. Urine was analyzed for cytomegalovirus. One astronaut did not shed any targeted virus in samples collected during the three mission phases. Shedding of Epstein–Barr virus, varicella-zoster virus, and cytomegalovirus was detected in 8 of the 23 astronauts. These viruses reactivated independently of each other. Reactivation of Epstein–Barr virus, varicella-zoster virus, and cytomegalovirus increased in frequency, duration, and amplitude (viral copy numbers) when compared to short duration (10 to 16 days) Space Shuttle Missions. No evidence of reactivation of herpes simplex virus type 1, herpes simplex virus type 2, or human herpes virus 6 was found. The mean diurnal trajectory of salivary cortisol changed significantly during flight as compared to before flight (P = 0.010). There was no statistically significant difference in levels of plasma cortisol or dehydoepiandosterone concentrations among time points before, during, and after flight for these international Space station crew members, although observed cortisol levels were lower at the mid and late-flight time points. The data confirm that astronauts undertaking long-duration Spaceflight experience both increased latent viral reactivation and changes in diurnal trajectory of salivary cortisol concentrations.

  • multiple latent viruses reactivate in astronauts during Space Shuttle Missions
    Brain Behavior and Immunity, 2014
    Co-Authors: Satish K Mehta, Mark L Laudenslager, Raymond P Stowe, Brian E Crucian, Clarence Sams, Duane L. Pierson
    Abstract:

    Latent virus reactivation and diurnal salivary cortisol and dehydroepiandrosterone were measured prospectively in 17 astronauts (16 male and 1 female) before, during, and after short-duration (12-16 days) Space Shuttle Missions. Blood, urine, and saliva samples were collected during each of these phases. Antiviral antibodies and viral load (DNA) were measured for Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and cytomegalovirus (CMV). Three astronauts did not shed any virus in any of their samples collected before, during, or after flight. EBV was shed in the saliva in all of the remaining 14 astronauts during all 3 phases of flight. Seven of the 14 EBV-shedding subjects also shed VZV during and after the flight in their saliva samples, and 8 of 14 EBV-shedders also shed CMV in their urine samples before, during, and after flight. In 6 of 14 crewmembers, all 3 target viruses were shed during one or more flight phases. Both EBV and VZV DNA copies were elevated during the flight phase relative to preflight or post-flight levels. EBV DNA in peripheral blood was increased preflight relative to post-flight. Eighteen healthy controls were also included in the study. Approximately 2-5% of controls shed EBV while none shed VZV or CMV. Salivary cortisol measured preflight and during flight were elevated relative to post-flight. In contrast DHEA decreased during the flight phase relative to both preflight and post-flight. As a consequence, the molar ratio of the area under the diurnal curve of cortisol to DHEA with respect to ground (AUCg) increased significantly during flight. This ratio was unrelated to viral shedding. In summary, three herpes viruses can reactivate individually or in combination during Spaceflight.

  • epstein barr virus shedding by astronauts during Space flight
    Brain Behavior and Immunity, 2005
    Co-Authors: Duane L. Pierson, Raymond P Stowe, Terry M Phillips, D J Lugg, Satish K Mehta
    Abstract:

    Patterns of Epstein-Barr virus (EBV) reactivation in 32 astronauts and 18 healthy age-matched control subjects were characterized by quantifying EBV shedding. Saliva samples were collected from astronauts before, during, and after 10 Space Shuttle Missions of 5-14 days duration. At one time point or another, EBV was detected in saliva from each of the astronauts. Of 1398 saliva specimens from 32 astronauts, polymerase chain reaction analysis showed that 314 (23%) were positive for EBV DNA. Examination by flight phase showed that 29% of the saliva specimens collected from 28 astronauts before flight were positive for EBV DNA, as were 16% of those collected from 25 astronauts during flight and 16% of those collected after flight from 23 astronauts. The mean number of EBV copies from samples taken during the flights was 417 per mL, significantly greater (p<.05) than the number of viral copies from the preflight (40) and postflight (44) phases. In contrast, the control subjects shed EBV DNA with a frequency of 3.7% and mean number of EBV copies of 40 per mL of saliva. Ten days before flight and on landing day, titers of antibody to EBV viral capsid antigen were significantly (p<.05) greater than baseline levels. On landing day, urinary levels of cortisol and catecholamines were greater than their preflight values. In a limited study (n=5), plasma levels of substance P and other neuropeptides were also greater on landing day. Increases in the number of viral copies and in the amount of EBV-specific antibody were consistent with EBV reactivation before, during, and after Space flight.

  • Changes in monocyte functions of astronauts.
    Brain behavior and immunity, 2005
    Co-Authors: Indreshpal Kaur, Elizabeth R. Simons, Victoria A. Castro, C. Mark Ott, Duane L. Pierson
    Abstract:

    Abstract As part of the systematic evaluation of the innate immune system for long duration Missions, this study focused on the antimicrobial functions of monocytes in astronauts participating in Spaceflight. The study included four Space Shuttle Missions and 25 astronauts. Nine non-astronauts served as controls. Blood specimens were collected 10 days before launch, within 3 h after landing, and again 3 days after landing. The number of monocytes did not differ significantly over the interval sampled in both the astronaut or control groups. However, following 5–11 days of Spaceflight, the astronauts’ monocytes exhibited reductions in ability to engulf Escherichia coli , elicit an oxidative burst, and degranulate. The phagocytic index was significantly reduced following Spaceflight when compared to control values. This reduction in phagocytosis was accompanied by changes in the expression of two surface markers involved in phagocytosis, CD32 and CD64. Levels of cortisol, epinephrine, and norepinephrine after Spaceflight did not increase over preflight values.

  • Changes in neutrophil functions in astronauts.
    Brain behavior and immunity, 2004
    Co-Authors: Indreshpal Kaur, Elizabeth R. Simons, Victoria A. Castro, C. Mark Ott, Duane L. Pierson
    Abstract:

    Exploration class human Spaceflight Missions will require astronauts with robust immune systems. Innate immunity will be an essential element for the healthcare maintenance of astronauts during these lengthy expeditions. This study investigated neutrophil phagocytosis, oxidative burst, and degranulation of 25 astronauts after four Space Shuttle Missions and in nine healthy control subjects. Space flight duration ranged from 5 to 11 days. Blood specimens were obtained 10 days before launch, immediately after landing, and 3 days after landing. The number of neutrophils increased by 85% at landing compared to preflight levels. The mean values for phagocytosis of Escherichia coli and oxidative burst capacity in neutrophils from astronauts on the 5-day mission were not significantly different from those observed in neutrophils from the control subjects. Before and after 9- to 11-day Missions, however, phagocytosis and oxidative burst capacities were significantly lower than control mean values. No consistent changes in degranulation or expression of surface markers were observed before or after any of the Space Missions. This study indicates that neutrophil phagocytic and oxidative functions are affected by factors associated with Space flight and this relationship may depend on mission duration.

L L Lowes - One of the best experts on this subject based on the ideXlab platform.

  • the atmospheric trace molecule spectroscopy atmos experiment deployment on the atlas Space Shuttle Missions
    Geophysical Research Letters, 1996
    Co-Authors: M R Gunson, M M Abbas, M C Abrams, M Allen, L R Brown, T L Brown, A Y Chang, A Goldman, F W Irion, L L Lowes
    Abstract:

    The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events provided measurements of more than 30 atmospheric trace gases at latitudes 3–49°N and 65–72°S, including observations both inside and outside the Antarctic polar vortex. The instrument configuration, data retrieval methodology, and mission background are described to place in context analyses of ATMOS data presented in this issue.

A Mcpherson - One of the best experts on this subject based on the ideXlab platform.

  • Comparative analysis of thaumatin crystals grown on earth and in microgravity.
    Acta crystallographica. Section D Biological crystallography, 1997
    Co-Authors: J D Ng, B Lorber, R Giege, S Koszelak, A Greenwood, A Mcpherson
    Abstract:

    The protein thaumatin was studied as a model macro-molecule for crystallization in microgravity-environment experiments conducted on two US Space Shuttle Missions (USML-2 and LMS). In this investigation, we have evaluated and compared the quality of Space- and earth-grown thaumatin crystals using X-ray diffraction analyses, and characterized them according to crystal size, diffraction resolution limit and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid-liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown in a microgravity environment were generally larger in volume and the total number of crystals was less, relative to crystals grown on earth. They diffracted to significantly higher resolution and with improved diffraction properties, as judged by relative plots of I/sigma versus resolution. The mosaicity of Space-grown crystals was significantly less than that of crystals grown on earth. Increased concentrations of protein in the crystallization chambers in microgravity led to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.

W Wang - One of the best experts on this subject based on the ideXlab platform.

  • prevalence of sleep deficiency and use of hypnotic drugs in astronauts before during and after Spaceflight an observational study
    Lancet Neurology, 2014
    Co-Authors: Joseph M. Ronda, Laura K Barger, Erin E Flynnevans, Alan Kubey, Lorcan Walsh, W Wang
    Abstract:

    Summary Background Sleep deprivation and fatigue are common subjective complaints among astronauts. Previous studies of sleep and hypnotic drug use in Space have been limited to post-flight subjective survey data or in-flight objective data collection from a small number of crew members. We aimed to characterise representative sleep patterns of astronauts on both short-duration and long-duration Spaceflight Missions. Methods For this observational study, we recruited crew members assigned to Space Transportation System Shuttle flights with in-flight experiments between July 12, 2001, and July 21, 2011, or assigned to International Space Station (ISS) expeditions between Sept 18, 2006, and March 16, 2011. We assessed sleep–wake timing objectively via wrist actigraphy, and subjective sleep characteristics and hypnotic drug use via daily logs, in-flight and during Earth-based data-collection intervals: for 2 weeks scheduled about 3 months before launch, 11 days before launch until launch day, and for 7 days upon return to Earth. Findings We collected data from 64 astronauts on 80 Space Shuttle Missions (26 flights, 1063 in-flight days) and 21 astronauts on 13 ISS Missions (3248 in-flight days), with ground-based data from all astronauts (4014 days). Crew members attempted and obtained significantly less sleep per night as estimated by actigraphy during Space Shuttle Missions (7·35 h [SD 0·47] attempted, 5·96 h [0·56] obtained), in the 11 days before Spaceflight (7·35 h [0·51], 6·04 h [0·72]), and about 3 months before Spaceflight (7·40 h [0·59], 6·29 h [0·67]) compared with the first week post-mission (8·01 h [0·78], 6·74 h [0·91]; p Interpretation Sleep deficiency in astronauts was prevalent not only during Space Shuttle and ISS Missions, but also throughout a 3 month preflight training interval. Despite chronic sleep curtailment, use of sleep-promoting drugs was pervasive during Spaceflight. Because chronic sleep loss leads to performance decrements, our findings emphasise the need for development of effective countermeasures to promote sleep. Funding The National Aeronautics and Space Administration.

Jeffrey R. Davis - One of the best experts on this subject based on the ideXlab platform.

  • Strategies for the preflight circadian shifting of Space Shuttle crews.
    The Journal of Clinical Pharmacology, 1994
    Co-Authors: Patricia A. Santy, Dean M. Faulk, Jeffrey R. Davis
    Abstract:

    In june, 1990, a workshop was put together at NASA/johnson Space Center to address difficulties the astronauts were having in adjusting their wake and sleep schedule, both immediately before and during Space Shuttle Missions. The workshop members, prominent investigators in human circadian research, developed a number of strategies by which astronauts could tackle the problem of circadian adaptation within the demanding timetable of a Space Shuttle mission. The strategies included both abrupt and gradual methods, and some approaches used artificial «very bright lights» to reset the physiologic circadian pacemaker. The strategies have since been operationally implemented on Space Shuttle flights, with good success

  • Strategies for the Preflight Circadian Shifting of Space Shuttle Crews
    Journal of clinical pharmacology, 1994
    Co-Authors: Patricia A. Santy, Dean M. Faulk, Jeffrey R. Davis
    Abstract:

    In June, 1990, a workshop was put together at NASA/Johnson Space Center to address difficulties the astronauts were having in adjusting their wake and sleep schedule, both immediately before and during Space Shuttle Missions. The workshop members, prominent investigators in human circadian research, developed a number of strategies by which astronauts could tackle the problem of circadian adaptation within the demanding timetable of a Space Shuttle mission. The strategies included both abrupt and gradual methods, and some approaches used artificial "very bright lights" to reset the physiologic circadian pacemaker. The strategies have since been operationally implemented on Space Shuttle flights, with good success. This is a report of the problems addressed by the workshop and its recommendations.