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.
Research Containing: Space Flight
Microgravity and hypergravity effects on fertilization of the salamander Pleurodeles waltl (urodele amphibian)
Effects of microgravity (microG) on fertilization were studied in the urodele amphibian Pleurodeles waltl on board the MIR space station. Genetic and cytomorphologic analyses ruled out parthenogenesis or gynogenesis and proved that fertilization did occur in microG. Actual fertilization was demonstrated by the analysis of the distribution of peptidase-1 genes, a polymorphic sex-linked enzyme, in progenies obtained in microG. Further evidence of fertilization was provided by the presence of spermatozoa in the perivitelline space and in the fertilization layer of the microG eggs and by the presence of a female pronucleus and male pronuclei in the egg cytoplasm. Experiments in microG and in 1.4G, 2G, and 3G hypergravity showed for the first time that, compared to eggs in 1G, several characteristics of the fertilization process including the cortical reaction and the microvillus transformations were altered depending on the gravitational force applied to the eggs. Microvillus elevation, the most evident feature, was reduced on microG-eggs and amplified on eggs submitted to 2G and 3G. No lethal consequences of these alterations on the early development of microG-eggs were observed.
Reinterpretation of mouse thyroid changes under space conditions: the contribution of confinement to damage
During space missions, astronauts work in a state of separation from their daily social environment and in physical confinement. It has been shown that confinement influences mood and brain cortical activity, but no data has been obtained with regard to its effect on the thyroid gland, the structure and function of which change during spaceflights. Here, we report the results of a study on the effects of confinement on mouse thyroid, which was implemented with the Mice Drawer System Facility maintained on the ground, a system used for spaceflight experiments. The results show that confinement changes the microscopic structure of the thyroid gland and that it exhibits symptoms similar to those that result from physiological and/or pathological hyperfunction. What is left unchanged, however, is the sphingomyelinase-thyrotropin receptor relationship, which is important for thyrotropin response with a consequential production of hormones that act on the metabolism of almost all tissues and reduces the production of calcitonin, a hormone involved in bone metabolism. During space missions, the overexpression of pleiotrophin, a widespread cytokine up-regulated after tissue injury that acts on bone remodeling, attenuates changes to the thyroid that are spaceflight-dependent; therefore we studied the thyroids of pleiotrophin-transgenic mice in the Mice Drawer System Facility. In confinement, pleiotrophin overexpression does not protect from the loss of calcitonin. The contribution of confinement to thyroid damage during spaceflights is discussed.
Loss of parafollicular cells during gravitational changes (microgravity, hypergravity) and the secret effect of pleiotrophin
It is generally known that bone loss is one of the most important complications for astronauts who are exposed to long-term microgravity in space. Changes in blood flow, systemic hormones, and locally produced factors were indicated as important elements contributing to the response of osteoblastic cells to loading, but research in this field still has many questions. Here, the possible biological involvement of thyroid C cells is being investigated. The paper is a comparison between a case of a wild type single mouse and a over-expressing pleiotrophin single mouse exposed to hypogravity conditions during the first animal experiment of long stay in International Space Station (91 days) and three similar mice exposed to hypergravity (2Gs) conditions. We provide evidence that both microgravity and hypergravity induce similar loss of C cells with reduction of calcitonin production. Pleiotrophin over-expression result in some protection against negative effects of gravity change. Potential implication of the gravity mechanic forces in the regulation of bone homeostasis via thyroid equilibrium is discussed.
Observing the mouse thyroid sphingomyelin under space conditions: a case study from the MDS mission in comparison with hypergravity conditions
This is a case report of apparent thyroid structural and functional alteration in a single mouse subjected to low Earth orbit spaceflight for 91 days. Histological examination of the thyroid gland revealed an increase in the average follicle size compared to that of three control animals and three animals exposed to hypergravity (2g) conditions. Immunoblotting analysis detected an increase in two thyroid gland enzymes, sphingomyelinase and sphingomyelin-synthase1. In addition, sphingomyelinase, an enzyme confined to the cell nucleus in the control animals, was found in the mouse exposed to hypogravity to be homogeneously distributed throughout the cell bodies. It represents the first animal observation of the influence of weightlessness on sphingomyelin metabolism.
Hematologic studies were performed on 21 ground control rats and 21 rats flown during the Spacelab Life Sciences-2 14-day mission. Group A (n = 5) was used to collect blood in flight and 9 days postflight, group B (n = 5) was injected with recombinant human erythropoietin (rhEpo), group C (n = 5) received saline as a control, and group D (n = 6) was killed in flight and tissues were collected. Results indicated no significant changes in peripheral blood erythroid elements between flight and ground control rats. The nonadherent bone marrow on flight day 13 showed a lower number of recombinant rat interleukin-3 (rrIL-3)-responsive and rrIL-3 + rhEpo-responsive blast-forming unit erythroid (BFU-e) colonies in flight rats compared with ground control rats. On landing day, a slight increase in the number of rhEpo + rrIL-3-responsive BFU-e colonies of flight animals compared with ground control rats was evident. Nine days postflight, bone marrow from flight rats stimulated with rhEpo alone or with rhEpo + rrIL-3 showed an increase in the number of colony-forming unit erythroid colonies and a decrease in BFU-e colonies compared with ground control rats. This is the first time that animals were injected with rhEpo and subsequently blood and tissues were collected during the spaceflight to study the regulation of erythropoiesis in microgravity.
Heart rate variability during centrifugation in astronauts prior to and after long duration spaceflight: Preliminary data
Spaceflight is known to induce vestibular and cardiovascular deconditioning. The current ESA SPIN project conducts research on vestibular and cardiovascular deconditioning after long duration spaceflight. Hereto, vestibular function and cardiovascular parameters are evaluated during centrifugation and during a tilt test in astronauts prior to and after spaceflight. The experiments are conducted using the ‘Visual and Vestibular Investigation System’. During rotation, cardiovascular and breathing parameters are recorded by means of the ‘Lifeshirt® system’ (Vivonoetics). The current analysis focuses on the cardio-respiratory response during 2 consecutive centrifugation runs, a counter clockwise (CCW) and a clockwise (CW). The RR-interval recorded postflight during the second CW rotation decreased significantly compared to the preflight data. No significant effects were observed on the parameters (amplitude, marker of vagal activity, and phase) of the respiratory sinus arrhythmia (RSA). However, the time of respiration and the amplitude of the RSA were correlated. Our preliminary results suggest a postflight recovery problem of the sympathetic nervous system after activation and show that the respiration has a large influence on the RSA amplitude.
TL dose measurements on board the Russian segment of the ISS by the “Pille” system during Expedition-8, -9 and -10
The “Pille-MKS” thermoluminescent (TL) dosimeter system developed by the KFKI Atomic Energy Research Institute (KFKI AEKI) and BL-Electronics, consisting of 10 CaSO 4 :Dy bulb dosimeters and a compact reader, has been continuously operating on board the International Space Station (ISS) since October 2003. The dosimeter system is utilized for routine and extravehicular activity (EVA) individual dosimetry of astronauts/cosmonauts as part of the service system as well as for on board experiments, and is operated by the Institute for Biomedical Problems (IBMP). The system is unique in that it regularly provides accurate dose data right on board the space station, a feature that became increasingly important during the suspension of the Space Shuttle flights. Seven dosimeters are located at different places of the Russian segment of the ISS and are read out once a month. Two of these dosimeters are dedicated to EVAs and one is kept in the reader and will be read out automatically every 90 min. During coronal mass ejections impacting Earth some of the dosimeters serve for individual monitoring of the astronauts with readouts once or twice every day. In this paper we report the results of dosimetric measurements made on board the ISS during Expedition-8, -9 and -10 using the “Pille” portable thermoluminescent detector (TLD) system and we compare them with our previous measurements on different space stations.
An understanding of the various source of non-methane volatile organic compounds is one facet to ensuing the habitability of crewed spacecraft. Although the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in it and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of the trace contaminants can be associated to a single source, the majority have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic process of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, it has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes that, in many ways are comparable to human metabolism. As such, it can be expectant that microbial growth can lead to the release of cortile organic compounds (VOCs) into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented here as well as the possible types of VOCs that can result from such organisms. This will be correlated to the observation provided by ground-based analysis of ISS atmosphere samples.
The Constrained Vapor Bubble (CVB) Experiment in the Microgravity Environment of the International Space Station
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.