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Research Containing: Astronauts

Evaluating Bone Loss in ISS Astronauts

by on 22 August 2016in Biology & Biotechnology No comment

INTRODUCTION: The measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) is the Medical Assessment Test used at the NASA Johnson Space Center to evaluate whether prolonged exposure to spaceflight increases the risk for premature osteoporosis in International Space Station (ISS) astronauts. The DXA scans of crewmembers’ BMD during the first decade of the ISS existence showed precipitous declines in BMD for the hip and spine after the typical 6-mo missions. However, a concern exists that skeletal integrity cannot be sufficiently assessed solely by DXA measurement of BMD. Consequently, use of relatively new research technologies is being proposed to NASA for risk surveillance and to enhance long-term management of skeletal health in long-duration astronauts. Sibonga JD, Spector ER, Johnston SL, Tarver WJ. Evaluating bone loss in ISS astronauts.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630194

Comprehensive analysis of the skin fungal microbiota of astronauts during a half-year stay at the International Space Station

by on 22 August 2016in Biology & Biotechnology No comment

The International Space Station (ISS) is a huge manned construct located approximately 400 km above the earth and is inhabited by astronauts performing space experiments. Because the station is within a closed microgravity environment, the astronauts are subject to consistent stress. This study analyzed the temporal changes in the skin fungal microbiota of 10 astronauts using pyrosequencing and quantitative PCR assay before, during, and after their stay in the ISS. Lipophilic skin fungi, Malassezia predominated most samples regardless of the collection period, body site (cheek or chest), or subject. During their stay in the ISS, the level of Malassezia colonization changed by 7.6- +/- 7.5-fold (mean +/- standard deviation) and 9.5- +/- 24.2-fold in cheek and chest samples, respectively. At the species level, M. restricta, M. globosa, and M. sympodialis were more abundant. In the chest samples, the ratio of M. restricta to all Malassezia species increased, whereas it did not change considerably in cheek samples. Fungal diversity was reduced, and the ratio of Malassezia to all fungal colonization increased during the astronauts’ stay at the ISS. The ascomycetous yeast Cyberlindnera jadinii was detected in abundance in the in-flight sample of 5 of the 10 astronauts. The microorganism may have incidentally adhered to the skin during the preflight period and persisted on the skin thereafter. This observation suggests the ability of a specific or uncommon microorganism to proliferate in a closed environment. Our study is the first to reveal temporal changes in the skin fungal microbiota of ISS astronauts. These findings will provide information useful for maintaining the health of astronauts staying in the space environment for long periods and for preventing infection due to the human skin microbiota.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26773135

Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut – Initial Verification on the International Space Station

by on 22 August 2016in Biology & Biotechnology No comment

BACKGROUND: Musculoskeletal atrophy is one of the major problems of extended periods of exposure to weightlessness such as on the International Space Station (ISS). We developed the Hybrid Training System (HTS) to maintain an astronaut’s musculoskeletal system using an electrically stimulated antagonist to resist the volitional contraction of the agonist instead of gravity. The present study assessed the system’s orbital operation capability and utility, as well as its preventative effect on an astronaut’s musculoskeletal atrophy. METHODS: HTS was attached to the non-dominant arm of an astronaut staying on the ISS, and his dominant arm without HTS was established as the control (CTR). 10 sets of 10 reciprocal elbow curls were one training session, and 12 total sessions of training (3 times per week for 4 weeks) were performed. Pre and post flight ground based evaluations were performed by Biodex (muscle performance), MRI (muscle volume), and DXA (BMD, lean [muscle] mass, fat mass). Pre and post training inflight evaluations were performed by a hand held dynamometer (muscle force) and a measuring tape (upper arm circumference). RESULTS: The experiment was completed on schedule, and HTS functioned well without problems. Isokinetic elbow extension torque (Nm) changed -19.4% in HTS, and -21.7% in CTR. Isokinetic elbow flexion torque changed -23.7% in HTS, and there was no change in CTR. Total Work (Joule) of elbow extension changed -8.3% in HTS, and +0.3% in CTR. For elbow flexion it changed -23.3% in HTS and -32.6% in CTR. Average Power (Watts) of elbow extension changed +22.1% in HTS and -8.0% in CTR. For elbow flexion it changed -6.5% in HTS and -4.8% in CTR. Triceps muscle volume according to MRI changed +11.7% and that of biceps was +2.1% using HTS, however -0.1% and -0.4% respectively for CTR. BMD changed +4.6% in the HTS arm and -1.2% for CTR. Lean (muscle) mass of the arm changed only +10.6% in HTS. Fat mass changed -12.6% in HTS and -6.4% in CTR. CONCLUSIONS: These results showed the orbital operation capability and utility, and the preventive effect of HTS for an astronaut’s musculoskeletal atrophy. The initial flight data together with the ground data obtained so far will be utilized in the future planning of human space exploration.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26296204

Orthostatic Intolerance After ISS and Space Shuttle Missions

by on 22 August 2016in Biology & Biotechnology No comment

INTRODUCTION: Cardiovascular deconditioning apparently progresses with flight duration, resulting in a greater incidence of orthostatic intolerance following long-duration missions. Therefore, we anticipated that the proportion of astronauts who could not complete an orthostatic tilt test (OTT) would be higher on landing day and the number of days to recover greater after International Space Station (ISS) than after Space Shuttle missions. METHODS: There were 20 ISS and 65 Shuttle astronauts who participated in 10-min 80 degrees head-up tilt tests 10 d before launch, on landing day (R+0), and 3 d after landing (R+3). Fisher’s Exact Test was used to compare the ability of ISS and Shuttle astronauts to complete the OTT. Cox regression was used to identify cardiovascular parameters associated with OTT completion and mixed model analysis was used to compare the change and recovery rates between groups. RESULTS: The proportion of astronauts who completed the OTT on R+0 (2 of 6) was less in ISS than in Shuttle astronauts (52 of 65). On R+3, 13 of 15 and 19 of 19 of the ISS and Shuttle astronauts, respectively, completed the OTT. An index comprised of stroke volume and diastolic blood pressure provided a good prediction of OTT completion and was altered by spaceflight similarly for both astronaut groups, but recovery was slower in ISS than in Shuttle astronauts. CONCLUSIONS: The proportion of ISS astronauts who could not complete the OTT on R+0 was greater and the recovery rate slower after ISS compared to Shuttle missions. Thus, mission planners and crew surgeons should anticipate the need to tailor scheduled activities and level of medical support to accommodate protracted recovery after long-duration microgravity exposures.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630196

Physical Training for Long-Duration Spaceflight

by on 22 August 2016in Biology & Biotechnology No comment

INTRODUCTION: Physical training has been conducted on the International Space Station (ISS) for the past 10 yr as a countermeasure to physiological deconditioning during spaceflight. Each member space agency has developed its own approach to creating and implementing physical training protocols for their astronauts. We have divided physical training into three distinct phases (preflight, in-flight, and postflight) and provided a description of each phase with its constraints and limitations. We also discuss how each member agency (NASA, ESA, CSA, and JAXA) prescribed physical training for their crewmembers during the first 10 yr of ISS operations. It is important to understand the operational environment, the agency responsible for the physical training program, and the constraints and limitations associated with spaceflight to accurately design and implement exercise training or interpret the exercise data collected on ISS. As exploration missions move forward, resolving agency differences in physical training programs will become important to maximizing the effectiveness of exercise as a countermeasure and minimizing any mission impacts.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630191

Optic disc edema in an astronaut after repeat long-duration space flight

by on 22 August 2016in Biology & Biotechnology No comment

BACKGROUND: A number of ophthalmic findings including optic disc edema, globe flattening, and choroidal folds have been observed in several astronauts after long-duration space flights. The authors report the first astronaut with previously documented postflight ophthalmic abnormalities who developed new pathological changes after a repeat long-duration mission. METHODS: A case study of an astronaut with 2 long-duration (6 months) exposures to microgravity. Before and after his first long-duration space flight, he underwent complete eye examination, including fundus photography. Before and after his second flight, 9 years later, he underwent fundus photography, optical coherence tomography, ocular ultrasonography, and brain magnetic resonance imaging, as well as in-flight fundus photography and ultrasound. RESULTS: After his first long-duration mission, the astronaut was documented to have eye findings limited to unilateral choroidal folds and a single cotton wool spot. During a subsequent 6-month mission, he developed more widespread choroidal folds and new onset of optic disc edema in the same eye. CONCLUSION: Microgravity-induced anatomical changes that occurred during the first mission may have set the stage for recurrent or additional changes when the astronaut was subjected to physiological stress of repeat space flight.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23851997

The First 10 Years of Aerobic Exercise Responses to Long-Duration ISS Flights

by on 22 August 2016in Biology & Biotechnology No comment

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

Russian Countermeasure Systems for Adverse Effects of Microgravity on Long-Duration ISS Flights

by on 22 August 2016in Uncategorized No comment

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

The First Decade of ISS Exercise: Lessons Learned on Expeditions 1-25

by on 22 August 2016in Biology & Biotechnology No comment

INTRODUCTION: Long-duration spaceflight results in musculoskeletal, cardiorespiratory, and sensorimotor deconditioning. Historically, exercise has been used as a countermeasure to mitigate these deleterious effects that occur as a consequence of microgravity exposures. The International Space Station (ISS) exercise community describes their approaches, biomedical surveillance, and lessons learned in the development of exercise countermeasure modalities and prescriptions for maintaining health and performance among station crews. This report is focused on the first 10 yr of ISS defined as Expeditions 1-25 and includes only crewmembers with missions > 30 d on ISS for all 5 partner agencies (United States, Russia, Europe, Japan, and Canada). All 72 cosmonauts and astronauts participated in the ISS exercise countermeasures program. This Supplement presents a series of papers that provide an overview of the first decade of ISS exercise from a multidisciplinary, multinational perspective to evaluate the initial countermeasure program and record its operational limitations and challenges. In addition, we provide results from standardized medical evaluations before, during, and after each mission. Information presented in this context is intended to describe baseline conditions of the ISS exercise program. This paper offers an introduction to the subsequent series of manuscripts.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630187

Microgravity promotes osteoclast activity in medaka fish reared at the international space station

by on 22 August 2016in Biology & Biotechnology No comment

The bone mineral density (BMD) of astronauts decreases specifically in the weight-bearing sites during spaceflight. It seems that osteoclasts would be affected by a change in gravity; however, the molecular mechanism involved remains unclear. Here, we show that the mineral density of the pharyngeal bone and teeth region of TRAP-GFP/Osterix-DsRed double transgenic medaka fish was decreased and that osteoclasts were activated when the fish were reared for 56 days at the international space station. In addition, electron microscopy observation revealed a low degree of roundness of mitochondria in osteoclasts. In the whole transcriptome analysis, fkbp5 and ddit4 genes were strongly up-regulated in the flight group. The fish were filmed for abnormal behavior; and, interestingly, the medaka tended to become motionless in the late stage of exposure. These results reveal impaired physiological function with a change in mechanical force under microgravity, which impairment was accompanied by osteoclast activation.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26387549