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Record 10 of 1275
The effects of twelve weeks of bed rest on bone histology, biochemical markers of bone turnover, and calcium homeostasis in eleven normal subjects
Author and Affiliation:
Zerwekh, J. E.(University of Texas Southwestern Medical Center at Dallas, Center for Mineral Metabolism and Clinical Research, 75235-8885, United States)
Ruml, L. A.
Gottschalk, F.
Pak, C. Y.
Blomqvist, C. G. [Principal Investigator]
Abstract: This study was undertaken to examine the effects of 12 weeks of skeletal unloading on parameters of calcium homeostasis, calcitropic hormones, bone histology, and biochemical markers of bone turnover in 11 normal subjects (9 men, 2 women; 34 +/- 11 years of age). Following an ambulatory control evaluation, all subjects underwent 12 weeks of bed rest. An additional metabolic evaluation was performed after 12 days of reambulation. Bone mineral density declined at the spine (-2.9%, p = 0.092) and at the hip (-3.8%, p = 0.002 for the trochanter). Bed rest prompted a rapid, sustained, significant increase in urinary calcium and phosphorus as well as a significant increase in serum calcium. Urinary calcium increased from a pre-bed rest value of 5.3 mmol/day to values as high as 73 mmol/day during bed rest. Immunoreactive parathyroid hormone and serum 1,25-dihydroxyvitamin D declined significantly during bed rest, although the mean values remained within normal limits. Significant changes in bone histology included a suppression of osteoblastic surface for cancellous bone (3.1 +/- 1.3% to 1.9 +/- 1.5%, p = 0.0142) and increased bone resorption for both cancellous and cortical bone. Cortical eroded surface increased from 3.5 +/- 1.1% to 7.3 +/- 4.0% (p = 0.018) as did active osteoclastic surface (0.2 +/- 0.3% to 0.7 +/- 0.7%, p = 0.021). Cancellous eroded surface increased from 2.1 +/- 1.1% to 4.7 +/- 2.2% (p = 0.002), while mean active osteoclastic surface doubled (0.2 +/- 0.2% to 0.4 +/- 0.3%, p = 0.020). Serum biochemical markers of bone formation (osteocalcin, bone-specific alkaline phosphatase, and type I procollagen extension peptide) did not change significantly during bed rest. Urinary biochemical markers of bone resorption (hydroxyproline, deoxypyridinoline, and N-telopeptide of type I collagen) as well as a serum marker of bone resorption (type I collagen carboxytelopeptide) all demonstrated significant increases during bed rest which declined toward normal during reambulation. Thus, under the conditions of this study, the human skeleton appears to respond to unloading by a rapid and sustained increase in bone resorption and a more subtle decrease in bone formation.
Publication Date: Oct 01, 1998
Document ID:
20040142203
(Acquired Nov 09, 2004)
Subject Category: AEROSPACE MEDICINE
Document Type: Journal Article
Publication Information: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (ISSN 0884-0431); Volume 13; 10; 1594-601
Publisher Information: United States
Contract/Grant/Task Num: M01-RR00633; R01-16061
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: BED REST; BIOCHEMISTRY; BONES; CALCIUM; HISTOLOGY; HOMEOSTASIS; MARKERS; ADULTS; BIOMARKERS; BONE MINERAL CONTENT; CALCIFEROL; FEMALES; LOAD CARRYING CAPACITY; MALES; METABOLISM
Other Descriptors: BED REST; BONE REMODELING/PHYSIOLOGY; BONE AND BONES/PHYSIOLOGY; CALCIUM/METABOLISM/PHYSIOLOGY; HOMEOSTASIS; ADULT; BIOLOGICAL MARKERS; BONE DENSITY; FEMALE; HUMAN; INTESTINAL ABSORPTION; MALE; MIDDLE AGED; REFERENCE VALUES; SUPPORT, U.S. GOV'T, NON-P.H.S; SUPPORT, U.S. GOV'T, P.H.S; VITAMIN D/ANALOGS & DERIVATIVES/ANALYSIS; WEIGHT-BEARING/PHYSIOLOGY; NASA DISCIPLINE MUSCULOSKELETAL; NON-NASA CENTER
Availability Source: Other Sources
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