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Research Containing: Spaceflight

Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station

by on 9 June 2015in Biology & Biotechnology No comment

Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41–50 yr, body-mass index of 22–28 kg/m2) during long-term missions (flight lengths of 162–196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight (P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight (P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances.

Related URLs:
http://jap.physiology.org/jap/103/1/156.full.pdf

Prospects of medical monitoring of long-duration space flights by means of non-contact recording of physiological functions during sleep time

by on 9 June 2015in Biology & Biotechnology No comment

The methods used to investigate the body functional state in sleep under the conditions of a long-duration space flight are of great scientific and practical interest. The Sonocard experiment is based on the method of seismocardiography. The goal of this experiment is to validate and improve the procedure of non-contact recording the in-sleep physiological data for monitoring the crew state. The very first results have demonstrated that, as on Earth, sleep is crucial for recovery of the functional reserves expended during the daytime under the conditions of microgravity. Using the new technology, the recovery processes, as well as individual adaptation to a long-term space flight, can be studied. This method makes it possible to evaluate the sleep quality, mechanisms of recreation, and body functionality. These data may enrich substantially the information used by medical operators of space missions in the control centers.

Related URLs:
http://dx.doi.org/10.1134/S036211971107005X

Assessment of individual adaptation to microgravity during long term space flight based on stepwise discriminant analysis of heart rate variability parameters

by on 9 June 2015in Biology & Biotechnology No comment

Optimization of the cardiovascular system under conditions of long term space flight is provided by individual changes of autonomic cardiovascular control. Heart rate variability (HRV) analysis is an easy to use method under these extreme conditions. We tested the hypothesis that individual HRV analysis provides important information for crew health monitoring. HRV data from 14 Russian cosmonauts measured during long term space flights are presented (two times before and after flight, monthly in flight). HRV characteristics in the time and in the frequency domain were calculated. Predefined discriminant function equations obtained in reference groups (L1=−0.112⁎HR−1.006⁎SI−0.047⁎pNN50−0.086⁎HF; L2=0.140⁎HR−0.165⁎SI−1.293⁎pNN50+0.623⁎HF) were used to define four functional states. (1) Physiological normal, (2) prenosological, (3) premorbid and (4) pathological. Geometric mean values for the ISS cosmonauts based on L1 and L2 remained within normal ranges. A shift from the physiological normal state to the prenosological functional state during space flight was detected. The functional state assessed by HRV improved during space flight if compared to pre-flight and early post-flight functional states. Analysis of individual cosmonauts showed distinct patterns depending on the pre-flight functional state. Using the developed classification a transition process from the state of physiological normal into a prenosological state or premorbid state during different stages of space flight can be detected for individual Russian cosmonauts. Our approach to an estimation of HR regulatory pattern can be useful for prognostic purposes.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0094576511002189

Autonomic function testing on board the ISS—update on “Pneumocard”

by on 9 June 2015in Biology & Biotechnology No comment

The devices “Puls” and “Pneumocard” were developed to further investigate autonomic cardiovascular and respiratory function on board the ISS. Investigations on board the “Mir” station showed transient changes in neurohumoral regulation indicating individual adaptation of regulatory systems. Therefore, an experiment “Pulse” has been performed starting with the fifth expedition on the ISS. The aim of the experiment is to investigate adaptation of the autonomic nervous system by measuring cardiorespiratory parameters during standardized tests at zero-gravity. Our results suggest that the adaptation to zero-gravity in terms of the autonomic cardiorespiratory control was adequate in all cosmonauts ( n = 5 ) . However, the characteristics of the responses during flight depend on the individual regulatory type. The individual evaluation of the regulatory systems especially during the initial stages of flight, during episodes of space sickness and after landing may shed light on critical changes of functional reserves and allow to reduce inflight and postflight disturbances.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0094576506004164

Post-Spaceflight Recovery of Biomechanical Properties of Murine Intervertebral Discs

by on 9 June 2015in Biology & Biotechnology No comment

Prolonged exposure to microgravity during spaceflight is thought to adversely affect the human spine because of reports that disc herniation risk is increased post-spaceflight. The increased herniation risk is highest during the first post-spaceflight year, and gradually subsides thereafter. Consequently, we hypothesized that the biomechanical properties of the intervertebral disc (IVD) deteriorate during spaceflight but then recover after acclimation to normal gravity. To test this hypothesis, we compared the compressive creep properties of caudal IVDs of murine subjects that had returned from a 13-day Shuttle mission (STS-133) to those of ground-based control mice. Spaceflight (n=6) and control (n=10) groups consisted of 13-week-old, BALB/c mice (11 weeks at launch). Mice were sacrificed +1 day, +5 days, or +7 days after the landing of STS-133. Disc height was measured in situ, and compressive creep rate was fit to a fluid transport model to determine disc biomechanical properties. Compared to controls, spaceflight mice had 12.6% lower disc height and 23.1% lower straindependence on swelling pressure. Biomechanical properties did not recover significantly over the 7-day post-flight period. Biomechanical properties of the murine caudal IVD were diminished by spaceflight, consistent with observations that prolonged exposure to microgravity increases disc herniation risk. These properties did not recover after short-term reacclimation to 1g loading.

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Functional Changes in the Snail Statocyst System Elicited by Microgravity

by on 9 June 2015in Biology & Biotechnology No comment

BACKGROUND: The mollusk statocyst is a mechanosensing organ detecting the animal's orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations. METHODOLOGY/PRINCIPAL FINDINGS: In terrestrial gastropod snail we studied the impact of 16- (Foton M-2) and 12-day (Foton M-3) exposure to microgravity in unmanned orbital missions on: (i) the whole animal behavior (Helix lucorum L.), (ii) the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L.), and (iii) the differential expression of the Helix pedal peptide (HPep) and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.). Experiments were performed 13–42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed. CONCLUSIONS/SIGNIFICANCE: Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism's ability to adapt to gravity changes. This simple animal model offers the possibility to describe general subcellular mechanisms of nervous system's response to conditions on Earth and in space.

Related URLs:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3066201/

Effects of spaceflight on innate immune function and antioxidant gene expression

by on 9 June 2015in Biology & Biotechnology No comment

Spaceflight conditions have a significant impact on a number of physiological functions due to psychological stress, radiation, and reduced gravity. To explore the effect of the flight environment on immunity, C57BL/6NTac mice were flown on a 13-day space shuttle mission (STS-118). In response to flight, animals had a reduction in liver, spleen, and thymus masses compared with ground (GRD) controls (P < 0.005). Splenic lymphocyte, monocyte/macrophage, and granulocyte counts were significantly reduced in the flight (FLT) mice (P < 0.05). Although spontaneous blastogenesis of splenocytes in FLT mice was increased, response to lipopolysaccharide (LPS), a B-cell mitogen derived from Escherichia coli, was decreased compared with GRD mice (P < 0.05). Secretion of IL-6 and IL-10, but not TNF-α, by LPS-stimulated splenocytes was increased in FLT mice (P < 0.05). Finally, many of the genes responsible for scavenging reactive oxygen species were upregulated after flight. These data indicate that exposure to the spaceflight environment can increase anti-inflammatory mechanisms and change the ex vivo response to LPS, a bacterial product associated with septic shock and a prominent Th1 response.

Related URLs:
http://jap.physiology.org/jap/106/6/1935.full.pdf
http://jap.physiology.org/content/jap/106/6/1935.full.pdf

Prevalence of sleep deficiency and use of hypnotic drugs in astronauts before, during, and after spaceflight: an observational study

by on 9 June 2015in Biology & Biotechnology No comment

BackgroundSleep 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.

Related URLs:
http://dx.doi.org/10.1016/S1474-4422(14)70122-X

MOLECULAR THERAPIES FOR DISUSE OSTEOPOROSIS

by on 9 June 2015in Biology & Biotechnology No comment

Microgravity causes changes in physiological systems that are both detrimental to human health and valuable for biomedical research. Some of the most pronounced and long-term changes occur in skeletal tissue, which experiences a profound and rapid wasting. Finding a countermeasure to the bone atrophy associated with weightlessness is necessary before long-duration human space exploration can be possible. However, these physiological changes can also be exploited as a biomedical model for osteoporosis, offering an extreme environment in which therapeutics can be tested and mechanisms examined. Utilizing space as a biomedical test-bed has been done on several flights: STS-41, 52, 57, 60, 62, 63, 77 and 108, the aims and results of which will be briefly summarized. The rational for spaceflight serving as a biomedical test-bed is that microgravity exposure (and resulting changes in the spacecraft environment) causes an accelerated model for biomedical disorders experienced, often as a result of the normal aging process, here on Earth. The most common target system for these flights was skeletal, with the goal of mimicking osteoporosis, but immune dysfunction, wound healing and muscle atrophy were also studied. Most recently (STS-108, December 2001), the biotechnology company Amgen examined the ability of osteoprotegerin (OPG) to mitigate the osteoporosis caused by microgravity. OPG is a protein that is critical to the differentiation and activation of bone resorbing osteoclasts. Amgen is developing OPG as a treatment for osteoporosis and the bone loss associated with metastatic bone cancer. Over the 12-day flight, the mice experienced a decline in bone strength (15-20% relative to ground controls) that was greater than that of ground-based disuse models. The mechanical testing data was complimented by serum, mRNA and histological analyses that indicated a decline in bone formation and an increase in bone resorption in addition to an inhibition of mineralization. OPG mitigated the decline in mechanical strength by preventing the increase in resorption and maintaining mineralization.

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The Constrained Vapor Bubble (CVB) Experiment in the Microgravity Environment of the International Space Station

by on 9 June 2015in Biology & Biotechnology No comment

The Constrained Vapor Bubble (CVB) experiment was run in the microgravity environment of the International Space Station as part of the Increment 23-24 which ended in September 2010. Here we present preliminary results which indicate significant differences in the operation of the CVB heat pipe in the micro-gravity environment as compared to the Earth's gravity. The temperature profile data along the heat pipe indicate that the heat pipe behavior is affected favorably by increased capillary flow and adversely by the absence of convective heat transfer as a heat loss mechanism. Image data of the liquid profile in the grooves of the heat pipe indicate that the curvature gradient is considerably different from that on Earth. An initial discussion of the data collected is presented.

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