INTRODUCTION: Aerobic deconditioning may occur during International Space Station (ISS) flights. This paper documents findings from exercise testing conducted before, during, and after ISS expeditions. METHODS: There were 30 male and 7 female astronauts on ISS missions (48 to 219 d, mean 163 d) who performed cycle exercise protocols consisting of 5-min stages eliciting 25%, 50%, and 75% peak oxygen uptake (Vo(2peak)). Tests were conducted 30 to 90 d before missions, on flight day 15 and every 30 flight days thereafter, and on recovery (R) days +5 and +30. During pre- and postflight tests, heart rate (HR) and metabolic gas exchange were measured. During flight, extrapolation of the HR and Vo2 relationship to preflight-measured peak HR provided an estimate of Vo(2peak), referred to as the aerobic capacity index (ACI). RESULTS: HR during each exercise stage was elevated (P < 0.05) and oxygen pulse was reduced (P < 0.05) on R+5 compared to preflight; however, no other metabolic gas analysis values significantly changed. Compared to preflight, the ACI declined (P < 0.001) on R+5, but recovered to levels greater than preflight by R+30 (P = 0.008). During flight, ACI decreased below preflight values, but increased with mission duration (P < 0.001). CONCLUSIONS: Aerobic deconditioning likely occurs initially during flight, but ACI recovers toward preflight levels as flight duration increases, presumably due to performance of exercise countermeasures. Elevated HR and lowered oxygen pulse on R+5 likely results from some combination of relative hypovolemia, lowered cardiac stroke volume, reduced cardiac distensibility, and anemia, but recovery occurs by R+30.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630198
Research Containing: Time Factors
Russian Countermeasure Systems for Adverse Effects of Microgravity on Long-Duration ISS Flights
INTRODUCTION: The system of countermeasures for the adverse effects of microgravity developed in the USSR supported the successful implementation of long-duration spaceflight (LDS) programs on the Salyut and Mir orbital stations and was subsequently adapted for flights on the International Space Station (ISS). From 2000 through 2010, crews completed 26 ISS flight increments ranging in duration from 140 to 216 d, with the participation of 27 Russian cosmonauts. These flights have made it possible to more precisely determine a crew-member’s level of conditioning, better assess the advantages and disadvantages of training processes, and determine prospects for future developments.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630192
Perception of affordances during long-term exposure to weightlessness in the International Space station
On Earth, visual eye height (VEH)–the distance from the observer’s line of gaze to the ground in the visual scene–constitutes an effective cue in perceiving affordance such as the passability through apertures, based on the assumption that one’s feet are on the ground. In the present study, we questioned whether an observer continues to use VEH to estimate the width of apertures during long-term exposure to weightlessness, where contact with the floor is not required. Ten astronauts were tested in preflight, inflight in the International Space Station, and postflight sessions. They were asked to adjust the opening of a virtual doorway displayed on a laptop device until it was perceived to be just wide enough to pass through (i.e., the critical aperture). We manipulated VEH by raising and lowering the level of the floor in the visual scene. We observed an effect of VEH manipulation on the critical aperture. When VEH decreased, the critical aperture decreased too, suggesting that widths relative to the body were perceived to be larger when VEH was smaller. There was no overall significant session effect, but the analysis of between-subjects variability revealed two participant profile groups. The effect of weightlessness was different for these two groups even though the VEH strategy remained operational during spaceflight. This study shows that the VEH strategy appears to be very robust and can be used, if necessary, in inappropriate circumstances such as free-floating, perhaps promoted by the nature of the visual scene.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26224263
Mechanical unloading of bone in microgravity reduces mesenchymal and hematopoietic stem cell-mediated tissue regeneration
Mechanical loading of mammalian tissues is a potent promoter of tissue growth and regeneration, whilst unloading in microgravity can cause reduced tissue regeneration, possibly through effects on stem cell tissue progenitors. To test the specific hypothesis that mechanical unloading alters differentiation of bone marrow mesenchymal and hematopoietic stem cell lineages, we studied cellular and molecular aspects of how bone marrow in the mouse proximal femur responds to unloading in microgravity. Trabecular and cortical endosteal bone surfaces in the femoral head underwent significant bone resorption in microgravity, enlarging the marrow cavity. Cells isolated from the femoral head marrow compartment showed significant down-regulation of gene expression markers for early mesenchymal and hematopoietic differentiation, including FUT1(-6.72), CSF2(-3.30), CD90(-3.33), PTPRC(-2.79), and GDF15(-2.45), but not stem cell markers, such as SOX2. At the cellular level, in situ histological analysis revealed decreased megakaryocyte numbers whilst erythrocytes were increased 2.33 fold. Furthermore, erythrocytes displayed elevated fucosylation and clustering adjacent to sinuses forming the marrow-blood barrier, possibly providing a mechanistic basis for explaining spaceflight anemia. Culture of isolated bone marrow cells immediately after microgravity exposure increased the marrow progenitor’s potential for mesenchymal differentiation into in-vitro mineralized bone nodules, and hematopoietic differentiation into osteoclasts, suggesting an accumulation of undifferentiated progenitors during exposure to microgravity. These results support the idea that mechanical unloading of mammalian tissues in microgravity is a strong inhibitor of tissue growth and regeneration mechanisms, acting at the level of early mesenchymal and hematopoietic stem cell differentiation.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/25011075
Rapid culture-independent microbial analysis aboard the International Space Station (ISS)
A new culture-independent system for microbial monitoring, called the Lab-On-a-Chip Application Development Portable Test System (LOCAD-PTS), was operated aboard the International Space Station (ISS). LOCAD-PTS was launched to the ISS aboard Space Shuttle STS-116 on December 9, 2006, and has since been used by ISS crews to monitor endotoxin on cabin surfaces. Quantitative analysis was performed within 15 minutes, and sample return to Earth was not required. Endotoxin (a marker of Gram-negative bacteria) was distributed throughout the ISS, despite previous indications that mostbacteria on ISS surfaces were Gram-positive [corrected].Endotoxin was detected at 24 out of 42 surface areas tested and at every surface site where colony-forming units (cfu) were observed, even at levels of 4-120 bacterial cfu per 100 cm(2), which is below NASA in-flight requirements (<10,000 bacterial cfu per 100 cm(2)). Absent to low levels of endotoxin (<0.24 to 1.0 EU per 100 cm(2); defined in endotoxin units, or EU) were found on 31 surface areas, including on most panels in Node 1 and the US Lab. High to moderate levels (1.01 to 14.7 EU per 100 cm(2)) were found on 11 surface areas, including at exercise, hygiene, sleeping, and dining facilities. Endotoxin was absent from airlock surfaces, except the Extravehicular Hatch Handle (>3.78 EU per 100 cm(2)). Based upon data collected from the ISS so far, new culture-independent requirements (defined in EU) are suggested, which are verifiable in flight with LOCAD-PTS yet high enough to avoid false alarms. The suggested requirements are intended to supplement current ISS requirements (defined in cfu) and would serve a dual purpose of safeguarding crew health (internal spacecraft surfaces <20 EU per 100 cm(2)) and monitoring forward contamination during Constellation missions (surfaces periodically exposed to the external environment, including the airlock and space suits, <0.24 EU per 100 cm(2)).
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/19845447
Rapid culture-independent microbial analysis aboard the international space station (ISS) stage two: quantifying three microbial biomarkers
Abstract A portable, rapid, microbial detection unit, the Lab-On-a-Chip Application Development Portable Test System (LOCAD-PTS), was launched to the International Space Station (ISS) as a technology demonstration unit in December 2006. Results from the first series of experiments designed to detect Gram-negative bacteria on ISS surfaces by quantifying a single microbial biomarker lipopolysaccharide (LPS) were reported in a previous article. Herein, we report additional technology demonstration experiments expanding the on-orbit capabilities of the LOCAD-PTS to detecting three different microbial biomarkers on ISS surfaces. Six different astronauts on more than 20 occasions participated in these experiments, which were designed to test the new beta-glucan (fungal cell wall molecule) and lipoteichoic acid (LTA; Gram-positive bacterial cell wall component) cartridges individually and in tandem with the existing Limulus Amebocyte Lysate (LAL; Gram-negative bacterial LPS detection) cartridges. Additionally, we conducted the sampling side by side with the standard culture-based detection method currently used on the ISS. Therefore, we present data on the distribution of three microbial biomarkers collected from various surfaces in every module present on the ISS at the time of sampling. In accordance with our previous experiments, we determined that spacecraft surfaces known to be frequently in contact with crew members demonstrated higher values of all three microbial molecules. Key Words: Planetary protection-Spaceflight-Microbiology-Biosensor. Astrobiology 12, 830-840.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/22984871
Dose distribution in the depth of the tissue-equivalent ball phantom modeling location of human body critical organs inside the compartments of the International space station
Goal of the investigation is to study and to analyze radiation dose distribution in cosmonaut's body during long-term mission aboard the International space station (ISS). The established patterns of dose distribution under different conditions of the experiment allow simplify evaluation of dose accumulation by spacecrew. Dose from ionizing space radiation was determined with the help of thermoluminescent dosimeters mounted in conditional depths of critical organs in human body modeled in a dosimetric device, i.e.–a ball-like tissue-equivalent phantom designed and manufactured in Russia for international space experiment Matreshka-R. The article reports experimental data disclosing the character and levels of exposure to ionizing radiation inside the Service module crew quarters during ISS missions 8 and 9 (425 days, 2004-2005) and the docking compartment (SO1) during ISS missions 15 and 16 (285 days, 2007-2008).
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/20120916
Assessment of Nutrient Stability in Foods from the Space Food System After Long-Duration Spaceflight on the ISS
ABSTRACT: Maintaining an intact nutrient supply in the food system flown on spacecraft is a critical issue for mission success and crew health. Ground-based evidence indicates that some vitamins may be altered and fatty acids oxidized (and therefore rendered useless, or even dangerous) by long-term storage and by exposure to radiation, both of which will be issues for long-duration exploration missions in space. In this study, the stability of nutrients was investigated in food samples exposed to spaceflight on the Intl. Space Station (ISS). A total of 6 replicates of 5 different space food items, a multivitamin, and a vitamin D supplement were packaged into 4 identical kits and were launched in 2006 on the space shuttle. After 13, 353, 596, and 880 d of spaceflight aboard the ISS, the kits were returned to Earth. Nine replicates of each food item and vitamin, from the same lots as those sent into space, remained in an environmental chamber on Earth to serve as controls at each time point. Vitamins, hexanal, oxygen radical absorbance capacity, and amino acids were measured in identical-lot food samples at each time point. After 596 d of spaceflight, differences in intact vitamin concentrations due to duration of storage were observed for most foodstuffs, but generally, nutrients from flight samples did not degrade any faster than ground controls. This study provided the 1st set of spaceflight data for investigation of nutrient stability in the food system, and the results will help NASA design food systems for both ISS and space exploration missions.
Related URLs:
http://dx.doi.org/10.1111/j.1750-3841.2009.01265.x
An artificial testis for production of rat haploid cells
PURPOSE: We attempted to apply the microgravity cell culture system for rat testicular germ cell maturation in vitro. METHODS: Primary spermatocytes were isolated from immature male rat by sedimentation velocity. Sertoli cells were isolated from another immature male by enzyme digestions. Sertoli cell aggregates were plated into conventional tissue culture flasks and incubated at 37 degrees C for 48 hours. These pretreated Sertoli-enriched monocultures were used in preparing Sertoli cell-primary spermatocyte cocultures. And then, primary spermatocytes and Sertoli cells were cocultured in a microgravity cell culture device for 28 days. RESULTS: Cell viability rate is more than 50 % after a 28-day long period of incubation. Furthermore, about 23 % haploid germ cells are observed. CONCLUSIONS: These results using primary spermatocyte coculture with Sertoli cell aggregates under microgravity show that it is possible to mature these cells up to the round spermatid and even to elongating/elongated steps. It may be possible to overcome the male sterility due to maturation arrest at the primary spermatocyte stage.
Related URLs:
http://ovidsp.ovid.com/ovidweb.cgi?T=JS&CSC=Y&NEWS=N&PAGE=fulltext&D=emed6&AN=14566684
http://sfxhosted.exlibrisgroup.com/mayo?sid=OVID:embase&id=pmid:14566684&id=doi:10.1055%2Fs-2003-41616&issn=0001-7868&isbn=&volume=34&issue=4&spage=273&pages=273-275&date=2003&title=Aktuelle+Urologie&atitle=An+artificial+testis+for+production+of+rat+haploid+cells&aulast=Yamamoto&pid=%3Cauthor%3EYamamoto+Y.%3C%2Fauthor%3E&%3CAN%3E14566684%3C%2FAN%3E
Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance
About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their ability to stand for 10 min postflight. Preflight, women and presyncopal men had low vascular resistance, with the women having the lowest. Postflight, women experienced higher rates of presyncope (100 vs. 20%; P = 0.001) and greater losses of plasma volume (20 vs. 7%; P < 0.05) than men. Also, presyncopal subjects had lower standing mean arterial pressure (P < or = 0.001) and vascular resistance (P < 0.05), smaller increases in norepinephrine (P < or = 0.058) and greater increases in epinephrine (P < or = 0.058) than nonpresyncopal subjects. Presyncopal subjects had a strong dependence on plasma volume to maintain standing stroke volume. These findings suggest that postflight presyncope is greatest in women, and this can be ascribed to a combination of inherently low-resistance responses, a strong dependence on volume status, and relative hypoadrenergic responses. Conversely, high vascular resistance and postflight hyperadrenergic responses prevent presyncope.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/11796668