Document Detail

Bone metabolism and nutritional status during 30-day head-down-tilt bed rest.
MedLine Citation:
PMID:  22995395     Owner:  NLM     Status:  MEDLINE    
Bed rest studies provide an important tool for modeling physiological changes that occur during spaceflight. Markers of bone metabolism and nutritional status were evaluated in 12 subjects (8 men, 4 women; ages 25-49 yr) who participated in a 30-day -6° head-down-tilt diet-controlled bed rest study. Blood and urine samples were collected twice before, once a week during, and twice after bed rest. Data were analyzed using a mixed-effects linear regression with a priori contrasts comparing all days to the second week of the pre-bed rest acclimation period. During bed rest, all urinary markers of bone resorption increased ~20% (P < 0.001), and serum parathyroid hormone decreased ~25% (P < 0.001). Unlike longer (>60 days) bed rest studies, neither markers of oxidative damage nor iron status indexes changed over the 30 days of bed rest. Urinary oxalate excretion decreased ~20% during bed rest (P < 0.001) and correlated inversely with urinary calcium (R = -0.18, P < 0.02). These data provide a broad overview of the biochemistry associated with short-duration bed rest studies and provide an impetus for using shorter studies to save time and costs wherever possible. For some effects related to bone biochemistry, short-duration bed rest will fulfill the scientific requirements to simulate spaceflight, but other effects (antioxidants/oxidative damage, iron status) do not manifest until subjects are in bed longer, in which case longer studies or other analogs may be needed. Regardless, maximizing research funding and opportunities will be critical to enable the next steps in space exploration.
Jennifer L L Morgan; Sara R Zwart; Martina Heer; Robert Ploutz-Snyder; Karen Ericson; Scott M Smith
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-09-20
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-16     Completed Date:  2013-04-29     Revised Date:  2014-06-27    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1519-29     Citation Subset:  IM    
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MeSH Terms
Antioxidants / metabolism
Bed Rest* / adverse effects
Biological Markers / blood,  urine
Bone Density
Bone Remodeling*
Bone and Bones / metabolism*
Calcium / urine
Head-Down Tilt*
Iron / blood
Linear Models
Middle Aged
Nutritional Status*
Oxalic Acid / urine
Oxidative Stress
Parathyroid Hormone / blood
Space Flight*
Time Factors
Weightlessness Simulation* / adverse effects
Grant Support
Reg. No./Substance:
0/Antioxidants; 0/Biological Markers; 0/PTH protein, human; 0/Parathyroid Hormone; 9E7R5L6H31/Oxalic Acid; E1UOL152H7/Iron; SY7Q814VUP/Calcium
Comment In:
J Urol. 2013 Feb;189(2):574   [PMID:  23312167 ]
Erratum In:
J Appl Physiol (1985). 2014 May 15;116(10):1343

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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