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Research Containing: Human Research

[Mechanisms of human osteopenia and some peculiarities of bone metabolism in weightlessness conditions]

by on 9 June 2015in Biology & Biotechnology No comment

Systematically results and new analysis data on the investigation of human bone system in space flight, the orbital station Mir and International Space Station, are presented. The bone mineral density, bone mineral content, identified as bone mass and body composition using dual energy X-ray absorptiometry were measured. Theoretically, an expected bone mass loss in trabecular tissue of lower skeletal half may by described as a quickly developing but reversible osteopenia and considered as evidence of functional adaptation of bone tissue to the changing mechanical load. A hypothesis of main mechanisms of osteopenia in microgravity is presented. High individual variability of bone mass losses and stability of individual pattern of correlation between bone mass losses in different skeletal segments were found. It is not possible to identify the relationship between bone mass losses and duration of space missions. Therefore it is not a sufficient ground to calculate the probability of reaching the critical level of bone demineralization by prolonged space flight. The same relates to the probability of prognosis of bone quality changes. There is data about dual energy X-ray absorptiometry that is insufficient for this prognosis. The main direction of investigations is presented which might optimize the interplanetary mission from the point of view of skeletal mechanical functions preservation.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/22645949

Characteristics of local human skeleton responses to microgravity and drug treatment for osteoporosis in clinic

by on 9 June 2015in Biology & Biotechnology No comment

Analysis of the results of long-term investigations of bones in cosmonauts on board Mir orbital station(OS) and International Space Station (ISS) (n = 80) was performed. Theoretically predicted (evolutionary predefined) change in mass of different skeleton bones was found to be correlated (r = 0.904) with the position relative to Earth’s gravity vector. Vector dependence of bone loss results from local specificity of expression of bone metabolism genes, which reflects mechanical prehistory of skeleton structures in the evolution of Homo erectus. Genetic polymorphism is accountable for high individual variability of bone loss, which is attested by the dependence of bone loss rate on polymorphism of certain genetic markers of bone metabolism. The type of the orbital vehicle did not affect the individual-specific stability of the bone loss ratio in different segments of the skeleton. This fact is considered as a phenotype fingerprint of local metabolism in the form of a locus-specific spatial structure of distribution of non-collagen proteins responsible for position regulation of endosteal metabolism. Drug treatment of osteoporosis (n = 107) evidences that recovery rate depends on bone location; the most likely reason is different effectiveness of local osteotropic intervention into areas of bustling resorption.

Related URLs:
http://dx.doi.org/10.1134/S0362119714070184
http://link.springer.com/article/10.1134%2FS0362119714070184

Space sickness on earth

by on 9 June 2015in Biology & Biotechnology No comment

During the first days in space, i.e., after a transition from 1G to 0G, more than 50% of the astro- (and cosmonauts) suffer from the Space Adaptation Syndrome (SAS).The symptoms of SAS, like nausea and dizziness, are especially provoked by head movements. Astronauts have mentioned close similarities between the symptoms of SAS and the symptoms they experienced after a 1 hour centrifuge run on Earth, i.e., after a transition from 3G to 1G (denoted by Sickness Induced by Centrifugation, SIC). During several space missions, we related susceptibility to SAS and to SIC in 11 astronauts and found 4 of them being susceptible to both SIC and SAS, and 7 being not susceptible to SIC nor to SAS. This correspondence in susceptibility suggests that SIC and SAS share the same underlying mechanism. To further study this mechanism, several vestibular parameters have been investigated (e.g. postural stability, vestibularly driven eye movements, subjective vertical). We found some striking changes in individual cases that are possibly due to the centrifuge run. However, the variability between subjects generally is very large, making physiological links to SIC and SAS still hard to find

Related URLs:
http://dx.doi.org/10.1007/BF02919464

Fluid shifts, vasodilatation and ambulatory blood pressure reduction during long duration spaceflight

by on 9 June 2015in Biology & Biotechnology No comment

Acute weightlessness in space induces a fluid shift leading to central volume expansion. Simultaneously, blood pressure is either unchanged or decreased slightly. Whether these effects persist for months in space is unclear. Twenty-four hour ambulatory brachial arterial pressures were automatically recorded at 1–2 h intervals with portable equipment in eight male astronauts: once before launch, once between 85 and 192 days in space on the International Space Station and, finally, once at least 2 months after flight. During the same 24 h, cardiac output (rebreathing method) was measured two to five times (on the ground seated), and venous blood was sampled once (also seated on the ground) for determination of plasma catecholamine concentrations. The 24 h average systolic, diastolic and mean arterial pressures (mean ± se) in space were reduced by 8 ± 2 mmHg (P = 0.01; ANOVA), 9 ± 2 mmHg (P < 0.001) and 10 ± 3 mmHg (P = 0.006), respectively. The nightly blood pressure dip of 8 ± 3 mmHg (P = 0.015) was maintained. Cardiac stroke volume and output increased by 35 ± 10% and 41 ± 9% (P < 0.001); heart rate and catecholamine concentrations were unchanged; and systemic vascular resistance was reduced by 39 ± 4% (P < 0.001). The increase in cardiac stroke volume and output is more than previously observed during short duration flights and might be a precipitator for some of the vision problems encountered by the astronauts. The spaceflight vasodilatation mechanism needs to be explored further.

Related URLs:
http://dx.doi.org/10.1113/jphysiol.2014.284869

T-cell immunity and cytokine production in cosmonauts after long-duration space flights

by on 9 June 2015in Biology & Biotechnology No comment

Long-duration spaceflight effects on T-cell immunity and cytokine production were studied in 12 Russian cosmonauts flown onto the International Space Station. Specific assays were performed before launch and after landing and included analysis of peripheral leukocyte distribution, analysis of T-cell phenotype, expression of activation markers, apoptosis, proliferation of T cells in response to a mitogen, concentrations of cytokines in supernatants of cell cultures. Statistically significant increase was observed in leukocytes’, lymphocytes’, monocytes’ and granulocytes’ total number, increase in percentage and absolutely number of CD3+CD4+-cells, CD4+CD45RA+-cells and CD4+CD45RA+/CD4+CD45RО+ ratio, CD4+CD25+Bright regulatory cells (p<0,05) in peripheral blood after landing. T-lymphocytes’ capacity to present CD69 and CD25 on its own surfaces was increased for the majority of crewmembers. Analysis of T-cell response to PHA-stimulation in vitro revealed there were some trends toward reduced proliferation of stimulated T-lymphocytes. There was an apparent post flight decrease in secreted IFN-g for the majority of crewmembers and in most instances there was elevation in secreted IL-10. It revealed depression of IFN-g/IL-10 ratio after flight. Correlation analysis according to Spearman’s rank correlation test established significant positive correlations (p<0.05) between cytokine production and T-cell activation (CD25+, CD38+) and negative correlation (p<0.05) between cytokine production and number of bulk memory CD4+T-cells (CD45RO+). Thus, these results suggest that T-cell dysfunction can be conditioned by cytokine dysbalance and could lead to development of disease after long-duration space flights.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0094576510003243

Biochemical Markers of Bone Tissue Metabolism in Cosmonauts after a Prolonged Spaceflight

by on 9 June 2015in Biology & Biotechnology No comment

Parameters of calcium homeostasis and its hormonal regulation, including biochemical markers of bone metabolism, were measured in the blood serum of Russian cosmonauts after prolonged flights on the International Space Station during the period from 2000 to 2003. The duration of the spaceflights was 129–196 days. Flight factors had an impact on calcium and bone tissue metabolism after a flight. Increased levels of osteogenesis and resorption markers were detected in the blood of the cosmonauts in the early rehabilitation period after a spaceflight. The prevalence of resorption over the formation of new bone tissue was observed in the early rehabilitation period, when the hormonal system maintaining calcium homeostasis was activated.

Related URLs:
http://dx.doi.org/10.1007/s10747-005-0115-z

Locomotor function after long-duration space flight: effects and motor learning during recovery

by on 9 June 2015in Biology & Biotechnology No comment

Astronauts returning from space flight and performing Earth-bound activities must rapidly transition from the microgravity-adapted sensorimotor state to that of Earth's gravity. The goal of the current study was to assess locomotor dysfunction and recovery of function after long-duration space flight using a test of functional mobility. Eighteen International Space Station crewmembers experiencing an average flight duration of 185 days performed the functional mobility test (FMT) pre-flight and post-flight. To perform the FMT, subjects walked at a self selected pace through an obstacle course consisting of several pylons and obstacles set up on a base of 10-cm-thick, medium-density foam for a total of six trials per test session. The primary outcome measure was the time to complete the course (TCC, in seconds). To assess the long-term recovery trend of locomotor function after return from space flight, a multilevel exponential recovery model was fitted to the log-transformed TCC data. All crewmembers exhibited altered locomotor function after space flight, with a median 48% increase in the TCC. From the fitted model we calculated that a typical subject would recover to 95% of his/her pre-flight level at approximately 15 days post-flight. In addition, to assess the early motor learning responses after returning from space flight, we modeled performance over the six trials during the first post-flight session by a similar multilevel exponential relation. We found a significant positive correlation between measures of long-term recovery and early motor learning (P < 0.001) obtained from the respective models. We concluded that two types of recovery processes influence an astronaut's ability to re-adapt to Earth's gravity environment. Early motor learning helps astronauts make rapid modifications in their motor control strategies during the first hours after landing. Further, this early motor learning appears to reinforce the adaptive realignment, facilitating re-adaptation to Earth's 1-g environment on return from space flight.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/20135100

Vestibular-somatosensory convergence in head movement control during locomotion after long-duration space flight

by on 9 June 2015in Biology & Biotechnology No comment

Space flight causes astronauts to be exposed to adaptation in both the vestibular and body load-sensing somatosensory systems. The goal of these studies was to examine the contributions of vestibular and body load-sensing somatosensory influences on vestibular mediated head movement control during locomotion after long-duration space flight. Subjects walked on a motor driven treadmill while performing a gaze stabilization task. Data were collected from three independent subject groups that included bilateral labyrinthine deficient (LD) patients, normal subjects before and after 30 minutes of 40% bodyweight unloaded treadmill walking, and astronauts before and after long-duration space flight. Motion data from the head and trunk segments were used to calculate the amplitude of angular head pitch and trunk vertical translation movement while subjects performed a gaze stabilization task, to estimate the contributions of vestibular reflexive mechanisms in head pitch movements. Exposure to unloaded locomotion caused a significant increase in head pitch movements in normal subjects, whereas the head pitch movements of LD patients were significantly decreased. This is the first evidence of adaptation of vestibular mediated head movement responses to unloaded treadmill walking. Astronaut subjects showed a heterogeneous response of both increases and decreases in the amplitude of head pitch movement. We infer that body load-sensing somatosensory input centrally modulates vestibular input and can adaptively modify vestibularly mediated head-movement control during locomotion. Thus, space flight may cause central adaptation of the converging vestibular and body load-sensing somatosensory systems leading to alterations in head movement control.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23000615

Do Psychological Decrements Occur During the 2nd Half of Space Missions?

by on 9 June 2015in Biology & Biotechnology No comment

PURPOSE. Anecdotal reports from space and studies from space analogue settings on Earth suggest that people living and working for long periods of time in isolated and confined environments (ICEs) experience mood and performance decrements after the halfway point of the mission. According to this view, the halfway point is seen as an important milestone, in that people are happy to arrive at this point in time, but then realize that they have another half to go until they can return home. This may result in drops in morale and mood and the emergence of interpersonal problems, especially in the weeks after the halfway point (the “3rd quarter phenomenon”). METHODS. A review of the literature found some ICE studies that supported the emergence of 2nd half decrements as a typical phenomenon and other studies that did not. To test for such time effects in space, we studied 13 astronauts and 17 cosmonauts who participated in the Shuttle/Mir and International Space Station (ISS) programs to see if there were mood and group behavior decrements in the 2nd half of the missions, which typically lasted 4 to 7 months on-orbit. Subjects completed weekly questionnaires composed of mood and interpersonal environment measures that allowed us to track crewmember psychosocial status over time. RESULTS. We failed to find evidence of substantial changes in mood or interpersonal behavior over time, either in the second half or during any quarter of the missions. Patterns varied between individuals: some seemed to show decrements in the 2nd half, but this was not true for the majority. CONCLUSIONS. On-orbit space crews do not typically exhibit decrements in psychosocial functioning in the 2nd half of their missions. The perception that this may be a general phenomenon may be due to memorable anecdotal reports from individuals. One possible reason for the lack of such decrements on-orbit may be related to the activities of support personnel in Mission Control in helping crewmembers cope with long-duration missions, unlike the case of people wintering in the Antarctic who may receive less support from the outside. Because such Earth-initiated support will be less feasible on a long distance planetary mission, it may be that expeditionary crewmembers traveling to Mars and beyond may exhibit 2nd half problems, so it is important to continue monitoring them for emotional and interpersonal problems throughout the mission.

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Heavy ions light flashes and brain functions: recent observations at accelerators and in spaceflight

by on 9 June 2015in Biology & Biotechnology No comment

Interactions between ionizing radiation in space and brain functions, and the related risk assessments, are among the major concerns when programming long permanence in space, especially when outside the protective shield of the Earth's magnetosphere. The light flashes (LF) observed by astronauts in space, mostly when dark adapted, are an example of these interactions; investigations in space and on the ground showed that these effects can originate with the action of ionizing radiation in the eye. Recent findings from ALTEA, an interdisciplinary and multiapproach program devoted to the study of different aspects of the radiation–brain functions interaction, are presented in this paper. These include: (i) study of radiation passing through the astronauts' eyes in the International Space Station (≈20 ions min −1 , excluding H and fast and very slow He), measured in conjunction with reporting of the perception of LF; (ii) preliminary electrophysiological evidence of these events in astronauts and in patients during heavy ion therapy; and (iii) in vitro results showing the radiation driven activation of rhodopsin at the start of the phototransduction cascade in the process of vision. These results are in agreement with our previous work on mice. A brief but complete summary of the earlier works is also reported to permit a discussion of the results.

Related URLs:
http://stacks.iop.org/1367-2630/10/i=7/a=075010