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Current Selection Filters |
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| Risk 1: Accelerated Bone Loss and Fracture Risk |
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| Crosscutting Area : Human Health and Countermeasures |
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 Discipline : Bone Loss |
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| Description : Osteoporosis associated with age-related bone loss may occur at an earlier age due to failure to recover bone lost during space flight. |
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Context / Risk Factors :
This risk may be influenced by age, baseline bone mass density (BMD), gender, nutrition, or muscle loss.
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| Justification / Rationale : Crewmembers lose bone during long-duration space flight, especially in weight bearing bones.Calcium and bone metabolism are altered, and failure to recover lost bone (mission- and age related), can lead to increased risk of fractures at a younger age. ISS crewmembers will be affected to varying degrees. Mitigation strategies are under investigation for ISS missions. Bone loss is not considered a significant problem on a 30-day mission to the Moon. Exploration (Mars) crews will be affected to varying degrees. |
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| Reference Missions :
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Risk Rating
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Current Countermeasures
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- Nutrition
- Exercise (resistive and aerobic)
- Crew Screening and preparation
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Projected Countermeasures or Mitigations and Other Deliverables with their CRL/TRL scores
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- Biophysical modalities [CRL 5]
- Crew Screening [CRL 1]
- Exercise and fitness regimens [CRL 6-7]
- Hormone replacement therapy [CRL 1]
- Nutrition [CRL 4]
- Pharmacological (including bisphosphonates) [CRL 7]
- Rehabilitation strategies [CRL 3]
- Spacesuit design [CRL 1]
- Artificial gravity
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Research & Technology Questions
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| 1a |
What is the relative risk of sustaining a traumatic and/or stress fracture for a given decrement in bone mineral density, or alteration in bone geometry, in an astronaut-equivalent population who are physically active? |
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| 1b |
Will a period of rapid bone loss in hypogravity be followed by a slower rate of loss approaching a basal bone mineral density (BMD)? What are the estimated site-specific fracture risks as one approaches basal BMD? |
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| 1c |
Is there an additive or synergistic effect of gonadal hormone deficiency in men or women on bone loss during prolonged exposure to hypogravity? |
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| 1d |
What biophysical modalities, nutritional modifications, and pharmacological agents (alone or in combination) will most effectively minimize the decrease in bone mass due to extended hypogravity exposure? |
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| 1e |
What are the specifics of the optimal exercise regimen with regard to mode, duration, intensity and frequency, to be followed during exposure to hypogravity so as to minimize decreases in bone mass? Is impact loading an essential element and, if so, how can it be produced in hypogravity? |
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| 1f |
What combination of exercise, biophysical modalities, nutritional modifications, and/or pharmacological agent(s) is most effective, efficient (minimal crew time), and safe in preventing bone loss during exposure to hypogravity? |
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| 1g |
What are the important predictors for estimating site-specific bone loss and fracture risk during hypogravity exposure, including, but not limited to ethnicity, gender, genetics, age, baseline bone density and geometry, nutritional status, fitness level and prior microgravity exposure? |
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| 1h |
Does the hypogravity environment change the nutritional requirements for optimal bone health? |
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| 1i |
What diagnostic tools can be utilized during multi-year missions to monitor and quantify changes in bone mass and bone strength? |
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| 1j |
What systemic adaptations to hypogravity are important contributory factors to bone loss, evaluations of which are essential for effective countermeasure development (e.g., fluid shifts, altered blood flow, immune system adaptations)? |
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| 1k |
Are hypogravity-induced changes in bone density, geometry, and architecture reversible upon encountering partial gravity exposure, or on return to full gravity (1-G)? |
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| 1l |
What regimen (exercise, pharmacological, nutritional, or biomechanical including impact loading or artificial gravity exposure) will most effectively hasten restoration of bone mass and/or bone strength (geometry and architecture) to pre-flight values in returning crewmembers? |
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Related Risks
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Important References
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Bikle DD, Sakata T, Halloran BP. The impact of skeletal unloading on bone formation. Gravit Space Biol Bull. 2003 Jun;16(2):45-54. Review.
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Cancedda R, Muraglia A. Osteogenesis in altered gravity. Adv Space Biol Med. 2002;8:159-76. Review.
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Heer M, Kamps N, Biener C, Korr C, Boerger A, Zittenman A, Stehle P, Drummer C. Calcium metabolism in microgravity. Eur J Med Res. 1999 Sep 9;4(9): 357-60. Review.
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Jennings RT, Bagian JP. Musculoskeletal injury review in the U.S. space program. Aviat Space Environ Med. 1996 Aug; 67(8): 762-6.
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Schneider SM, Amonette WE, Blazine K, Bentley J, Lee SM, Loehr JA, Moore AD Jr, Rapley M, Mulder ER, Smith SM. Training with the International Space Station interim resistive exercise device. Med Sci Sports Exerc. 2003 Nov;35(11):1935-45.
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Shapiro JR, Schneider V. Countermeasure development: future research targets. J Gravit Physiol. 2000 Jul;7(2):P1-4.
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Cena H, Sculati M, Roggl C. Nutritional concerns and possible countermeasures to nutritional issues related to space flight. Eur J Nutr. 2003 Apr;42(2):99-110. Review.
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