Bone loss Archives - Page 2 of 2 - Research on StationResearch on Station

Long-duration space flight and bed rest effects on testosterone and other steroids

by cfynanon 9 June 2015in Biology & Biotechnology No comment

CONTEXT: Limited data suggest that testosterone is decreased during space flight, which could contribute to bone and muscle loss. OBJECTIVE: The main objective was to assess testosterone and hormone status in long- and short-duration space flight and bed rest environments and to determine relationships with other physiological systems, including bone and muscle. DESIGN: Blood and urine samples were collected before, during, and after long-duration space flight. Samples were also collected before and after 12- to 14-d missions and from participants in 30- to 90-d bed rest studies. SETTING: Space flight studies were conducted on the International Space Station and before and after Space Shuttle missions. Bed rest studies were conducted in a clinical research center setting. Data from Skylab missions are also presented. PARTICIPANTS: All of the participants were male, and they included 15 long-duration and nine short-duration mission crew members and 30 bed rest subjects. MAIN OUTCOME MEASURES: Serum total, free, and bioavailable testosterone were measured along with serum and urinary cortisol, serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and SHBG. RESULTS: Total, free, and bioavailable testosterone was not changed during long-duration space flight but were decreased (P < 0.01) on landing day after these flights and after short-duration space flight. There were no changes in other hormones measured. Testosterone concentrations dropped before and soon after bed rest, but bed rest itself had no effect on testosterone. CONCLUSIONS: There was no evidence for decrements in testosterone during long-duration space flight or bed rest.

Characteristics of local human skeleton responses to microgravity and drug treatment for osteoporosis in clinic

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Analysis of the results of long-term investigations of bones in cosmonauts on board Mir orbital station(OS) and International Space Station (ISS) (n = 80) was performed. Theoretically predicted (evolutionary predefined) change in mass of different skeleton bones was found to be correlated (r = 0.904) with the position relative to Earth’s gravity vector. Vector dependence of bone loss results from local specificity of expression of bone metabolism genes, which reflects mechanical prehistory of skeleton structures in the evolution of Homo erectus. Genetic polymorphism is accountable for high individual variability of bone loss, which is attested by the dependence of bone loss rate on polymorphism of certain genetic markers of bone metabolism. The type of the orbital vehicle did not affect the individual-specific stability of the bone loss ratio in different segments of the skeleton. This fact is considered as a phenotype fingerprint of local metabolism in the form of a locus-specific spatial structure of distribution of non-collagen proteins responsible for position regulation of endosteal metabolism. Drug treatment of osteoporosis (n = 107) evidences that recovery rate depends on bone location; the most likely reason is different effectiveness of local osteotropic intervention into areas of bustling resorption.

The current state of bone loss research: Data from spaceflight and microgravity simulators

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Bone loss is a well documented phenomenon occurring in humans both in short- and in long-term spaceflights. This phenomenon can be also reproduced on the ground in human and animals and also modeled in cell-based analogs. Since space flights are infrequent and expensive to study the biomedical effects of microgravity on the human body, much of the known pathology of bone loss comes from experimental studies. The most commonly used in vitro simulators of microgravity are clinostats while in vivo simulators include the bed rest studies in humans and hindlimb unloading experiments in animals. Despite the numerous reports that have documented bone loss in wide ranges in multiple crew members, the pathology remains a key concern and development of effective countermeasures is still a major task. Thus far, the offered modalities have not shown much success in preventing or alleviating bone loss in astronauts and cosmonauts. The objective of this review is to capture the most recent research on bone loss from spaceflights, bed rest and hindlimb unloading, and in vitro studies utilizing cellular models in clinostats. Additionally, this review offers projections on where the research has to focus to ensure the most rapid development of effective countermeasures.

Related URLs:
http://dx.doi.org/10.1002/jcb.24454

Long-term changes in the density and structure of the human hip and spine after long-duration spaceflight

by cfynanon 9 June 2015in Biology & Biotechnology No comment

To determine the long-term effects of long-duration spaceflight, we measured bone mineral density and bone geometry of International Space Station (ISS) crewmembers using quantitative computed tomography (QCT) before launch, immediately upon their return, one year after return, and 2–4.5 years after return from the ISS. Eight crew members (7 male, 1 female, mean age 45±4 years at start of mission) who spent an average of 181 days (range 161–196 days) aboard the ISS took part in the study. Integral bone mineral density (iBMD), trabecular BMD (tBMD), bone mineral content (BMC), and vertebral cross-sectional area (CSA) were measured in the lumbar spine, and iBMD, tBMD, cortical BMD (cBMD), BMC, CSA, volume, and femoral neck section modulus were measured in the hip. Spine iBMD was 95% of the average preflight value upon return from the ISS and reached its preflight value over the next 2–4.5 years. Spine tBMD was 97% of the average preflight value upon return from the ISS and tended to decrease throughout the course of the study. Vertebral CSA remained essentially unchanged throughout the study. Hip iBMD was 91% of the preflight value upon return from the ISS and was 95% of the preflight value after 2–4.5 years of recovery. Hip tBMD was 88% of the preflight value upon return and recovered to only 93% of the preflight value after 1 year. At the 2- to 4.5-year time point, average tBMD was 88% of the preflight value. During the recovery period the total volume and cortical bone volume in the hip reached values of 114% and 110% of their preflight values, respectively. The combination of age-related bone loss, long-duration spaceflight, and re-adaptation to the 1-g terrestrial environment presumably produced these changes. These long-term data suggest that skeletal changes that occur during long-duration spaceflight persist even after multiple years of recovery. These changes have important implications for the skeletal health of crew members, especially those who make repeat trips to space.

IMPACT OF OSTEOCLAST PRECURSORS SUBJECTED TO RANDOM POSITIONING MACHINE ON OSTEOBLASTS

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Osteoblast-osteoclast interaction plays an important role in the bone remodeling. During long duration space flight, astronauts undergo serious bone loss mainly due to the disruption of equivalence between bone formation and bone resorption. Osteoclast precursors often operate under the control of osteoblasts. However, here we show that the osteoclast precursors could in turn influence osteoblasts. RAW264.7 cells, the murine osteoclast precursors, were treated in the simulated weightlessness produced by a Random Positioning Machine (RPM). After 72 h, conditioned mediums (CM) by the RAW264.7 cells from RPM (RCM) or static control (CCM) were collected and were used to culture osteoblastic-like MC3T3-E1 cells. The results showed that the RCM culture inhibited cell viability and slightly altered cell cycle, but the morphology of the MC3T3-E1 cells was not changed by RCM compared to that of CCM. Furthermore, the intracellular ALP level, NO release and expression of osteoblastic marker genes were all down-regulated by RCM culture. These results suggest that osteoclast precursors subjected to RPM exert negative regulation on osteoblasts.

Related URLs:
<Go to ISI>://WOS:000310159000027

Summary – Bone in microgravity environments: "Houston, we have a problem"

by cfynanon 9 June 2015in Biology & Biotechnology No comment

With the recent change in leadership at NASA, a sea change in research priorities at the agency has occurred. Monies once dedicated to life science research have been dramatically reduced in order to provide resources for development of a new Crew Exploration Vehicle, designed to replace the aging shuttle vehicles. Bone loss during space flight, once considered a "show-stopper" when long duration exploration missions were more central to NASA planning,no longer commands center stage. The prevailing sentiment appears to be that changes in bone with short-term missions to the International Space Station (ISS) or to the lunar surface will be too small to impact on mission outcomes and will be successfully mitigated with current exercise countermeasures, perhaps in combination with bisphosphonate therapy. Strategies to minimize bone loss with long-term spaceflight (e.g.,2-3 years’ duration) may not be necessary 10 years from now some speculate, given projections of improved pharmacological treatments or even the integration of artificial gravity on board exploration vehicles. It behooves bone biologists to carefully define the specific challenges to bone integrity incurred during (or following) the shorter 3- to 6-month Lunar or ISS missions planned for the next 10 years. Data presented during this session illustrate well that, with reference to microgravity effects on bone integrity, there is too much of "we don’t know what we don’t know"

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Research Containing: Bone loss

Long-duration space flight and bed rest effects on testosterone and other steroids

Characteristics of local human skeleton responses to microgravity and drug treatment for osteoporosis in clinic

The current state of bone loss research: Data from spaceflight and microgravity simulators

Long-term changes in the density and structure of the human hip and spine after long-duration spaceflight

IMPACT OF OSTEOCLAST PRECURSORS SUBJECTED TO RANDOM POSITIONING MACHINE ON OSTEOBLASTS

Summary – Bone in microgravity environments: "Houston, we have a problem"