Research Containing: Human

Modification of unilateral otolith responses following spaceflight

by cfynanon 22 August 2016in Biology & Biotechnology No comment

The aim of the study was to resolve the issue of spaceflight-induced, adaptive modification of the otolith system by measuring unilateral otolith responses in a pre- versus post-flight design. The study represents the first comprehensive approach to examining unilateral otolith function following space flight. Ten astronauts participated in unilateral otolith function tests three times preflight and up to four times after Shuttle flights from landing day through the subsequent 10 days. During unilateral centrifugation, utricular function was examined by the perceptual changes reflected by the subjective visual vertical (SVV) and the otolith-mediated ocular counter-roll, designated as utriculo-ocular response (UOR). Unilateral saccular reflexes were recorded by measurement of collic vestibular evoked myogenic potentials (cVEMP). The findings demonstrate a general increase in interlabyrinth asymmetry of otolith responses on landing day relative to preflight baseline, with subsequent reversal in asymmetry within 2-3 days. Recovery to baseline levels was achieved within 10 days. This fluctuation in asymmetry was consistent for the utricle tests (SVV and UOR) while apparently stronger for SVV. A similar asymmetry was observed during cVEMP testing. In addition, the results provide initial evidence of a dominant labyrinth. The findings require reconsideration of the otolith asymmetry hypothesis; in general, on landing day, the response from one labyrinth was equivalent to preflight values, while the other showed considerable discrepancy. The finding that one otolith response can return to one-g level within hours after re-entry while the other takes considerably longer demonstrates the importance of considering the otolith response as a result of both peripheral and associated central neural processing.

Relativistic electrons high doses at International Space Station and Foton M2/M3 satellites

by cfynanon 22 August 2016in Biology & Biotechnology, Earth Science and Remote Sensing, Physical Sciences No comment

The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the per- iod February 20 – April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°–60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 lGy h 1 behind 1.75 g cm 2 shielding at Foton M2, 2314 lGy h 1 behind 0.71 g cm 2 shielding at Foton M3 and 19,195 lGy h 1 (Flux is 8363 cm 2 s 1) behind les than 0.4 g cm 2 shielding at ISS.

International Space Station acoustics – a status report

by cfynanon 9 June 2015in Technology Development & Demonstration No comment

It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analysis and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 20031. Many new modules, and sleep stations have been added to the ISS since that time. In addition, noise mitigation efforts have reduced noise levels in some areas. As a result, the acoustic levels on the ISS have improved.

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Study of radiation conditions onboard the International space station by means of the Liulin-5 dosimeter

by cfynanon 9 June 2015in Physical Sciences No comment

For estimating radiation risk in space flights it is necessary to determine radiation dose obtained by critical organs of a human body. For this purpose the experiments with human body models are carried out onboard spacecraft. These models represent phantoms equipped with passive and active radiation detectors which measure dose distributions at places of location of critical organs. The dosimetric Liulin-5 telescope is manufactured with using three silicon detectors for studying radiation conditions in the spherical tissue-equivalent phantom on the Russian segment of the International space station (ISS). The purpose of the experiment with Liulin-5 instrument is to study dynamics of the dose rate and particle flux in the phantom, as well as variations of radiation conditions on the ISS over long time intervals depending on a phase of the solar activity cycle, orbital parameters, and presence of solar energetic particles. The Liulin-5 dosimeter measures simultaneously the dose rate and fluxes of charged particles at three depths in the radial channel of the phantom, as well as the linear energy transfer. The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.

Phantom—dosimeter for estimating effective dose onboard International Space Station

by cfynanon 9 June 2015in Physical Sciences No comment

The dose values in body's critical organs are necessary for estimating the effective dose. The tissue-equivalent phantom is used for such assessment as a rule. The spherical phantom is best fit for this goal. Therefore, the method developed on the basis of such phantom application becomes a good mean of effective dose estimating onboard the International Space Station. The main problems connected with developing a method of assessing an effective dose in the human's body organs with usage of a spherical phantom are presented in the paper. Proposed method can be used for monitoring the daily effective dose of crewmembers exposure for undisturbed radiation conditions of the flight.

Operational point of neural cardiovascular regulation in humans up to 6 months in space

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Entering weightlessness affects central circulation in humans by enhancing venous return and cardiac output. We tested whether the operational point of neural cardiovascular regulation in space sets accordingly to adopt a level close to that found in the ground-based horizontal position. Heart rate (HR), finger blood and brachial blood pressure (BP), and respiratory frequency were collected in 11 astronauts from nine space missions. Recordings were made in supine and standing positions at least 10 days before launch and during spaceflight (days 5–19, 45–67, 77–116, 146–180). Cross-correlation analyses of HR and systolic BP were used to measure three complementary aspects of cardiac baroreflex modulation: 1) baroreflex sensitivity, 2) number of effective baroreflex estimates, and 3) baroreflex time delay. A fixed breathing protocol was performed to measure respiratory sinus arrhythmia and low-frequency power of systolic BP variability. We found that HR and mean arterial pressure did not differ from preflight supine values for up to 6 mo in space. Respiration frequency tended to decrease during prolonged spaceflight. Concerning neural markers of cardiovascular regulation, we observed in-flight adaptations toward homeostatic conditions similar to those found in the ground-based supine position. Surprisingly, this was not the case for baroreflex time delay distribution, which had somewhat longer latencies in space. Except for this finding, our results confirm that the operational point of neural cardiovascular regulation in space sets to a level close to that of an Earth-based supine position. This adaptation level suggests that circulation is chronically relaxed for at least 6 mo in space.

Bone marrow fat accumulation after 60 days of bed rest persisted 1 year after activities were resumed along with hemopoietic stimulation: the Women International Space Simulation for Exploration study

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Immobility in bed and decreased mobility cause adaptations to most human body systems. The effect of immobility on fat accumulation in hemopoietic bone marrow has never been measured prospectively. The reversibility of marrow fat accumulation and the effects on hemopoiesis are not known. In the present study, 24 healthy women (age: 25–40 yr) underwent −6° head-down bed rest for 60 days. We used MRI to noninvasively measure the lumbar vertebral fat fraction at various time points. We also measured hemoglobin, erythropoietin, reticulocytes, leukocytes, platelet count, peripheral fat mass, leptin, cortisol, and C-reactive protein during bed rest and for 1 yr after bed rest ended. Compared with baseline, the mean (± SE) fat fraction was increased after 60 days of bed rest (+2.5 ± 1.1%, P < 0.05); the increase persisted 1 yr after the resumption of regular activities (+2.3 ± 0.8%, P < 0.05). Mean hemoglobin levels were significantly decreased 6 days after bed rest ended (−1.36 ± 0.20 g/dl, P < 0.05) but had recovered at 1 yr, with significantly lower mean circulating erythropoietin levels (−3.8 ± 1.2 mU/ml, P < 0.05). Mean numbers of neutrophils and lymphocytes remained significantly elevated at 1 yr (+617 ± 218 neutrophils/μl and +498 ± 112 lymphocytes/μl, both P < 0.05). These results constitute direct evidence that bed rest irreversibly accelerated fat accumulation in hemopoietic bone marrow. The 2.5% increase in fat fraction after 60 days of bed rest was 25-fold larger than expected from historical ambulatory controls. Sixty days of bed rest accelerated by 4 yr the normal bone marrow involution. Bed rest and marrow adiposity were associated with hemopoietic stimulation. One year after subjects returned to normal activities, hemoglobin levels were maintained, with 43% lower circulating erythropoietin levels, and leukocytes remained significantly elevated across lineages. Lack of mobility alters hemopoiesis, possibly through marrow fat accumulation, with potentially wide-ranging clinical consequences.

Evaluation of a novel basic life support method in simulated microgravity

by cfynanon 9 June 2015in Biology & Biotechnology No comment

BACKGROUND: If a cardiac arrest occurs in microgravity, current emergency protocols aim to treat patients via a medical restraint system within 2-4 min. It is vital that crewmembers have the ability to perform single-person cardiopulmonary resuscitation (CPR) during this period, allowing time for advanced life support to be deployed. The efficacy of the Evetts-Russomano (ER) method has been tested in 22 s of microgravity in a parabolic flight and has shown that external chest compressions (ECC) and mouth-to-mouth ventilation are possible. METHODS: There were 21 male subjects who performed both the ER method in simulated microgravity via full body suspension and at +1 Gz. The CPR mannequin was modified to provide accurate readings for ECC depth and a metronome to set the rate at 100 bpm. Heart rate, rate of perceived exertion, and angle of arm flexion were measured with an ECG, elbow electrogoniometers, and Borg scale, respectively. RESULTS: The mean (+/- SD) depth of ECC in simulated microgravity was lower in each of the 3 min compared to +1 G2. The ECC depth (45.7 +/- 2.7 mm, 42.3 +/- 5.5 mm, and 41.4 +/- 5.9 mm) and rate (104.5 +/- 5.2, 105.2 +/- 4.5, and 102.4 +/- 6.6 compressions/min), however, remained within CPR guidelines during simulated microgravity over the 3-min period. Heart rate, perceived exertion, and elbow flexion of both arms increased using the ER method. CONCLUSION: The ER method can provide adequate depth and rate of ECC in simulated microgravity for 3 min to allow time to deploy a medical restraint system. There is, however, a physiological cost associated with it and a need to use the flexion of the arms to compensate for the lack of weight.

Identification of proteins involved in inhibition of spheroid formation under microgravity

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Many types of cells transit in vitro from a two- to a three-dimensional growth, when they are exposed to microgravity. The underlying mechanisms are not yet understood. Hence, we investigated the impact of microgravity on protein content and growth behavior. For this purpose the human thyroid cancer cells FTC-133 were seeded either in recently developed cell containers that can endure enhanced physical forces and perform media changes and cell harvesting automatically or in T-25 culture flasks. All cells were cultured for 5 days at 1g. Afterwards, a part of the cell containers were flown to the International Space Station, while another part was kept on the ground. T-25 flasks were mounted on and next to a Random Positioning Machine. The cells were cultured for 12 days under the various conditions, before they were fixed with RNAlater. All fixed cultures showed monolayers, but three-dimensional aggregates were not detected. In a subsequent protein analysis, 180 proteins were identified by mass spectrometry. These proteins did not indicate significant differences between cells exposed to microgravity and their 1g controls. However, they suggest that an enhanced production of proteins related to the extracellular matrix could detain the cells from spheroid formation, while profilin-1 is phosphorylated This article is protected by copyright. All rights reserved

Epstein-Barr virus shedding by astronauts during space flight

by cfynanon 9 June 2015in Biology & Biotechnology No comment

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.

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Research Containing: Human

Modification of unilateral otolith responses following spaceflight

Relativistic electrons high doses at International Space Station and Foton M2/M3 satellites

International Space Station acoustics – a status report

Study of radiation conditions onboard the International space station by means of the Liulin-5 dosimeter

Phantom—dosimeter for estimating effective dose onboard International Space Station

Operational point of neural cardiovascular regulation in humans up to 6 months in space

Bone marrow fat accumulation after 60 days of bed rest persisted 1 year after activities were resumed along with hemopoietic stimulation: the Women International Space Simulation for Exploration study

Evaluation of a novel basic life support method in simulated microgravity

Identification of proteins involved in inhibition of spheroid formation under microgravity

Epstein-Barr virus shedding by astronauts during space flight