Glucocorticoid: A potential role in microgravity-induced bone loss

NASA Astrophysics Data System (ADS)

Yang, Jiancheng; Yang, Zhouqi; Li, Wenbin; Xue, Yanru; Xu, Huiyun; Li, Jingbao; Shang, Peng

2017-11-01

Exposure of animals and humans to conditions of microgravity, including actual spaceflight and simulated microgravity, results in numerous negative alterations to bone structure and mechanical properties. Although there are abundant researches on bone loss in microgravity, the explicit mechanism is not completely understood. At present, it is widely accepted that the absence of mechanical stimulus plays a predominant role in bone homeostasis disorders in conditions of weightlessness. However, aside from mechanical unloading, nonmechanical factors such as various hormones, cytokines, dietary nutrition, etc. are important as well in microgravity induced bone loss. The stress-induced increase in endogenous glucocorticoid (GC) levels is inevitable in microgravity environments. Moreover, it is well known that GCs have a detrimental effect to bone health at excess concentrations. Therefore, GC plays a potential role in microgravity-induced bone loss. This review summarizeds several studies and their prospective solutions to this hypothesis.

Combination of hindlimb suspension and immobilization by casting exaggerates sarcopenia by stimulating autophagy but does not worsen osteopenia.

PubMed

Speacht, Toni L; Krause, Andrew R; Steiner, Jennifer L; Lang, Charles H; Donahue, Henry J

2018-05-01

Astronauts in space experience a unique environment that causes the concomitant loss of bone and muscle. However, the interaction between these tissues and how osteopenia and sarcopenia affect each other is unclear. We explored this relationship by exaggerating unloading-induced muscle loss using a unilateral casting model in conjunction with hindlimb suspension (HLS). Five-month-old, male C57Bl/6J mice subjected to HLS for 2 weeks displayed a significant decrease in gastrocnemius and quadriceps weight (-9-10%), with a two-fold greater decrease in muscle mass observed in the HLS + casted limb. However, muscle from casted limbs had a higher rate of protein synthesis (+16%), compared to HLS alone, with coordinated increases in S6K1 (+50%) and 4E-BP1 (+110%) phosphorylation. Increased protein content for surrogate markers of autophagy, including LC3-II (+75%), Atg7 (+10%), and Atg5-12 complex (+20%) was only detected in muscle from the casted limb. In proximal tibias, HLS resulted in significant decreases in bone volume fraction (-24% vs -8%), trabecular number (-6% vs +0.3%), trabecular thickness (-10% vs -2%), and trabecular spacing (+8.4% vs +2%) compared to ground controls. There was no further bone loss in casted limbs compared to HLS alone. In tibia midshafts, HLS resulted in decreased total area (-2% vs +1%) and increased bone mineral density (+1% vs -0.3%) compared to ground controls. Cortical bone from casted limbs showed an increase in cortical thickness (+9% vs +2%) and cortical area/total area (+1% vs -0.6%) compared to HLS alone. Our results suggest that casting exacerbates unloading-induced muscle loss via activation of autophagy. Casting did not exacerbate bone loss suggesting that the unloading-induced loss of muscle and bone can be temporally dissociated and the effect of reduced muscle activity plays a relatively minor role compared to reduced load bearing on trabecular bone structure. Copyright © 2018 Elsevier Inc. All rights reserved.

Extending Rest between Unloading Cycles Does Not Enhance Bone's Long-Term Recovery.

PubMed

Manske, Sarah L; Vijayaraghavan, Surabhi; Tuthill, Alyssa; Brutus, Olivier; Yang, Jie; Gupta, Shikha; Judex, Stefan

2015-10-01

Multiple exposures to unloading are overall more deleterious to the skeleton than is single exposure, although the rate of bone loss may diminish during multiple exposures. Here, we determined whether extending the reambulation (RA) period from 3 wk to 9 wk will mitigate bone loss during three distinct 3-wk hindlimb unloading (HLU) periods and enhance long-term recovery in skeletally mature, genetically heterogeneous mice. Female adult mice (4 months old) were subjected to three cycles of 3-wk unloading with 3-wk or 9-wk RA periods in between. Mice were terminated 46 wk after initiation of the study. Outcome measures for the distal femur were determined from multiple in vivo micro-computed tomography scans and finite-element modeling. Tripling RA duration enhanced trabecular bone recovery in between HLU periods but also increased the rate of loss of bone volume fraction (bone volume/tissue volume) and metaphyseal stiffness during subsequent HLU periods. With shorter RA periods, the magnitude of bone loss decreased by the second HLU period, whereas this decrease was delayed with longer RA periods. RA duration did not affect long-term recovery 46 wk after the start of the experimental protocol, as both HLU groups had similar levels of bone volume/tissue volume, cortical area, and stiffness. Individual cage activity levels were unrelated to the magnitude of bone loss during HLU or bone recovery during RA. These data suggest that extending recovery duration between periods of unloading may provide temporary benefits but is an ineffective long-term strategy for combating the devastation of trabecular morphology and mechanics, as temporarily enhanced recovery is largely cancelled out by greater susceptibility to unloading. They also emphasize that cortical bone is more amenable to long-term recovery than is trabecular bone.

The role of 1,25-dihydroxyvitamin D in the inhibition of bone formation induced by skeletal unloading

NASA Technical Reports Server (NTRS)

Halloran, B. P.; Bikle, D. D.; Wronski, T. J.; GLOBUS. R.; Levens, M. J.; Morey-Holton, E.

1983-01-01

Skeletal unloading results in osteopenia. To examine the involvement of vitamin D in this process, the rear limbs of growing rats were unloaded and alterations in bone calcium and bone histology were related to changes in serum calcium (Ca), inorganic phosphorus (P sub i), 25-hydroxyvitamin D (25-OH-D), 24,25-dihydroxyvitamin D (24,25(OH)2D and 1,25-dihydroxyvitamin D (1,25(OH)2D. Acute skeletal unloading induced a transitory inhibition of Ca accumulation in unloaded bones. This was accompanied by a transitory rise in serum Ca, a 21% decrease in longitudinal bone growth (P 0.01), a 32% decrease in bone surface lined with osteoblasts (P .05), no change in bone surface lined with osteoclasts and a decrease in circulating (1,25(OH)2D. No significant changes in the serum concentrations of P sub i, 25-OH-D or 24,25(OH)2D were observed. After 2 weeks of unloading, bone Ca stabilized at approximately 70% of control and serum Ca and 1,25(OH)2D returned to control values. Maintenance of a constant serum 1,25(OH)2D concentration by chronic infusion of 1,25(OH)2D (Alza osmotic minipump) throughout the study period did not prevent the bone changes induced by acute unloading. These results suggest that acute skeletal unloading in the growing rat produces a transitory inhibition of bone formation which in turn produces a transitory hypercalcemia.

Sost, independent of the non-coding enhancer ECR5, is required for bone mechanoadaptation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robling, Alexander G.; Kang, Kyung Shin; Bullock, Whitney A.

Here, sclerostin ( Sost) is a negative regulator of bone formation that acts upon the Wnt signaling pathway. Sost is mechanically regulated at both mRNA and protein level such that loading represses and unloading enhances Sost expression, in osteocytes and in circulation. The non-coding evolutionarily conserved enhancer ECR5 has been previously reported as a transcriptional regulatory element required for modulating Sost expression in osteocytes. Here we explored the mechanisms by which ECR5, or several other putative transcriptional enhancers regulate Sost expression, in response to mechanical stimulation. We found that in vivo ulna loading is equally osteoanabolic in wildtype and Sostmore » –/– mice, although Sost is required for proper distribution of load-induced bone formation to regions of high strain. Using Luciferase reporters carrying the ECR5 non-coding enhancer and heterologous or homologous h SOST promoters, we found that ECR5 is mechanosensitive in vitro and that ECR5-driven Luciferase activity decreases in osteoblasts exposed to oscillatory fluid flow. Yet, ECR5–/– mice showed similar magnitude of load-induced bone formation and similar periosteal distribution of bone formation to high-strain regions compared to wildtype mice. Further, we found that in contrast to Sost–/– mice, which are resistant to disuse-induced bone loss, ECR5–/– mice lose bone upon unloading to a degree similar to wildtype control mice. ECR5 deletion did not abrogate positive effects of unloading on Sost, suggesting that additional transcriptional regulators and regulatory elements contribute to load-induced regulation of Sost.« less

Sost, independent of the non-coding enhancer ECR5, is required for bone mechanoadaptation

DOE PAGES

Robling, Alexander G.; Kang, Kyung Shin; Bullock, Whitney A.; ...

2016-09-04

Here, sclerostin ( Sost) is a negative regulator of bone formation that acts upon the Wnt signaling pathway. Sost is mechanically regulated at both mRNA and protein level such that loading represses and unloading enhances Sost expression, in osteocytes and in circulation. The non-coding evolutionarily conserved enhancer ECR5 has been previously reported as a transcriptional regulatory element required for modulating Sost expression in osteocytes. Here we explored the mechanisms by which ECR5, or several other putative transcriptional enhancers regulate Sost expression, in response to mechanical stimulation. We found that in vivo ulna loading is equally osteoanabolic in wildtype and Sostmore » –/– mice, although Sost is required for proper distribution of load-induced bone formation to regions of high strain. Using Luciferase reporters carrying the ECR5 non-coding enhancer and heterologous or homologous h SOST promoters, we found that ECR5 is mechanosensitive in vitro and that ECR5-driven Luciferase activity decreases in osteoblasts exposed to oscillatory fluid flow. Yet, ECR5–/– mice showed similar magnitude of load-induced bone formation and similar periosteal distribution of bone formation to high-strain regions compared to wildtype mice. Further, we found that in contrast to Sost–/– mice, which are resistant to disuse-induced bone loss, ECR5–/– mice lose bone upon unloading to a degree similar to wildtype control mice. ECR5 deletion did not abrogate positive effects of unloading on Sost, suggesting that additional transcriptional regulators and regulatory elements contribute to load-induced regulation of Sost.« less

Radiation and mechanical unloading effects on mouse vertebral bone: Ground-based models of the spaceflight environment

NASA Astrophysics Data System (ADS)

Alwood, Joshua Stewart

Astronauts on long-duration space missions experience increased ionizing radiation background levels and occasional acute doses of ionizing radiation from solar particle events, in addition to biological challenges introduced by weightlessness. Previous research indicates that cancer radiotherapy damages bone marrow cell populations and reduces mechanical strength of bone. However, the cumulative doses in radiotherapy are an order of magnitude or greater than dose predictions for long-duration space missions. Further detriments to the skeletal system are the disuse and mechanical unloading experienced during weightlessness, which causes osteopenia in weight-bearing cancellous bone (a sponge-like bony network of rods, plates and voids) and cortical bone (dense, compact bone). Studies of radiation exposure utilizing spaceflight-relevant types and doses, and in combination with mechanical unloading, have received little attention. Motivated by the future human exploration of the solar system, the effects of acute and increased background radiation on astronaut skeletal health are important areas of study in order to prevent osteopenic deterioration and, ultimately, skeletal fracture. This dissertation addresses how spaceflight-relevant radiation affects bone microarchitecture and mechanical properties in the cancellous-rich vertebrae and compares results to that of mechanical unloading. In addition, a period of re-ambulation is used to test whether animals recover skeletal tissue after irradiation. Whether radiation exposure displays synergism with mechanical unloading is further investigated. Finite element structural and statistical analyses are used to investigate how changes in architecture affect mechanical stress within the vertebra and to interpret the mechanical testing results. In this dissertation, ground-based models provide evidence that ionizing radiation, both highly energetic gamma-rays and charged iron ions, resulted in a persistent loss of cancellous bone in male mice. Mechanical unloading, by contrast, is shown to cause bone loss in the vertebrae via cancellous and cortical thinning that resulted in decreased whole-bone mechanical properties. The effects of mechanical unloading were altogether reversible in the vertebra after re-ambulation, though some residual alteration of trabecular morphology persisted. The combination of unloading and radiation exposure appeared to worsen the reductions of strength. Under either environmental condition, cancellous bone loss occurred near the vertebral endplates and at the centrum midplane. Finite element analysis suggested that tissue-level stresses increase in the centrum after either unloading or irradiation in agreement with the cellular-solid model of dense, plate-like trabeculae. Force-sharing between cancellous and cortical bone decreased after radiation, with stress concentrating on the cortex. In conclusion, acute exposure to spaceflight-relevant ionizing radiation altered trabecular microarchitecture and stress distribution, without a loss of whole-bone strength at the endpoints investigated, while unloading presented the greater immediate detriment to whole-bone mechanical properties. From a skeletal-health perspective, strategies to mitigate and counteract astronaut exposure to acute doses of radiation and mechanical unloading should be developed in preparation for long-term human spaceflight.

Modeled microgravity and hindlimb unloading sensitize osteoclast precursors to RANKL mediated osteoclastogenesis

PubMed Central

Saxena, Ritu; Pan, George; Dohm, Erik D.; McDonald, Jay M.

2010-01-01

Mechanical forces are essential to maintain skeletal integrity, and microgravity exposure leads to bone loss. The underlying molecular mechanisms leading to the changes in osteoblasts and osteoclast differentiation and function remain be to fully elucidated. Due to the infrequency of spaceflights and payload constraints, establishing in vitro and in vivo systems that mimic microgravity conditions becomes necessary. We have established a simulated microgravity (modeled microgravity, MMG) system to study the changes induced in osteoclast precursors. We observed that MMG, on its own was unable to induce osteoclastogenesis of osteoclast precursors, however, 24h of MMG activates osteoclastogenesis-related signaling molecules ERK, p38, PLCγ2, and NFATc1. RANKL (and/or M-CSF) stimulation for 3-4 days in gravity of cells that had been exposed to MMG for 24h, enhanced the formation of very large TRAP positive multinucleated (>30 nuclei) osteoclasts accompanied by an upregulation of osteoclast marker genes- TRAP and cathepsin K. To validate the in vitro system, we established the hindlimb unloading system using BALB/c mice and observed a decrease in BMD of femurs and a loss of 3D microstructure of both cortical and trabecular bone as determined by microCT. There was a marked stimulation of osteoclastogenesis as determined by the total number of TRAP positive multinucleated osteoclasts formed and also an increase in RANKL stimulated osteoclastogenesis from precursors removed from the tibias of mice after 28 days of hindlimb unloading. Contrary to earlier reported findings, we did not observe any histomorphometrical changes in the bone formation parameters. Thus, the above observations indicate that microgravity sensitizes osteoclast precursors for increased differentiation. The in vitro model system described here is potentially a valid system for testing drugs for preventing microgravity induced bone loss by targeting the molecular events occurring in microgravity-induced enhanced osteoclastogenesis. PMID:20589403

Effects of Plantar Vibration on Bone and Deep Fascia in a Rat Hindlimb Unloading Model of Disuse

PubMed Central

Huang, Yunfei; Fan, Yubo; Salanova, Michele; Yang, Xiao; Sun, Lianwen; Blottner, Dieter

2018-01-01

The deep fascia of the vertebrate body comprises a biomechanically unique connective cell and tissue layer with integrative functions to support global and regional strain, tension, and even muscle force during motion and performance control. However, limited information is available on deep fascia in relation to bone in disuse. We used rat hindlimb unloading as a model of disuse (21 days of hindlimb unloading) to study biomechanical property as well as cell and tissue changes to deep fascia and bone unloading. Rats were randomly divided into three groups (n = 8, each): hindlimb unloading (HU), HU + vibration (HUV), and cage-control (CON). The HUV group received local vibration applied to the plantar of both hind paws. Micro-computed tomography analyzed decreased bone mineral density (BMD) of vertebra, tibia, and femur in HU vs. CON. Biomechanical parameters (elastic modulus, max stress, yield stress) of spinal and crural fascia in HU were always increased vs. CON. Vibration in HUV only counteracted HU-induced tibia bone loss and crural fascia mechanical changes but failed to show comparable changes in the vertebra and spinal fascia on lumbar back. Tissue and cell morphometry (size and cell nuclear density), immunomarker intensity levels of anti-collagen-I and III, probed on fascia cryosections well correlated with biomechanical changes suggesting crural fascia a prime target for plantar vibration mechano-stimulation in the HU rat. We conclude that the regular biomechanical characteristics as well as tissue and cell properties in crural fascia and quality of tibia bone (BMD) were preserved by local plantar vibration in disuse suggesting common mechanisms in fascia and bone adaptation to local mechanovibration stimulation following hind limb unloading in the HUV rat. PMID:29875702

Effects of Plantar Vibration on Bone and Deep Fascia in a Rat Hindlimb Unloading Model of Disuse.

PubMed

Huang, Yunfei; Fan, Yubo; Salanova, Michele; Yang, Xiao; Sun, Lianwen; Blottner, Dieter

2018-01-01

The deep fascia of the vertebrate body comprises a biomechanically unique connective cell and tissue layer with integrative functions to support global and regional strain, tension, and even muscle force during motion and performance control. However, limited information is available on deep fascia in relation to bone in disuse. We used rat hindlimb unloading as a model of disuse (21 days of hindlimb unloading) to study biomechanical property as well as cell and tissue changes to deep fascia and bone unloading. Rats were randomly divided into three groups ( n = 8, each): hindlimb unloading (HU), HU + vibration (HUV), and cage-control (CON). The HUV group received local vibration applied to the plantar of both hind paws. Micro-computed tomography analyzed decreased bone mineral density (BMD) of vertebra, tibia, and femur in HU vs. CON. Biomechanical parameters (elastic modulus, max stress, yield stress) of spinal and crural fascia in HU were always increased vs. CON. Vibration in HUV only counteracted HU-induced tibia bone loss and crural fascia mechanical changes but failed to show comparable changes in the vertebra and spinal fascia on lumbar back. Tissue and cell morphometry (size and cell nuclear density), immunomarker intensity levels of anti-collagen-I and III, probed on fascia cryosections well correlated with biomechanical changes suggesting crural fascia a prime target for plantar vibration mechano-stimulation in the HU rat. We conclude that the regular biomechanical characteristics as well as tissue and cell properties in crural fascia and quality of tibia bone (BMD) were preserved by local plantar vibration in disuse suggesting common mechanisms in fascia and bone adaptation to local mechanovibration stimulation following hind limb unloading in the HUV rat.

Bone Density and High Salt Diets in a Space Flight Model

NASA Technical Reports Server (NTRS)

Arnaud, S. B.; Navidi, M.; Liang, M. T. C.; Wolinsky, I.

1999-01-01

High salt diets accelerate bone loss with aging in patients with postmenopausal osteoporosis except when calcium supplementation is provided. We have observed that the decrease in mineral content of growing femurs in juvenile rats, exposed to a space flight model which unloads the hind limbs , is substantially less in animals fed excess salt. To determine whether excess dietary salt has the same effect on the skeleton of the mature animal whose response to unloading is increased resorption and bone loss rather than impaired growth, we carried out a metabolic study in mature rats with hindlimbs unloaded by tailsuspension.

Spinal Cord Injury-Induced Osteoporosis: Pathogenesis and Emerging Therapies

PubMed Central

Battaglino, Ricardo A.; Lazzari, Antonio A.; Garshick, Eric; Morse, Leslie R.

2012-01-01

Spinal cord injury causes rapid, severe osteoporosis with increased fracture risk. Mechanical unloading after paralysis results in increased osteocyte expression of sclerostin, suppressed bone formation, and indirect stimulation of bone resorption. At this time there are no clinical guidelines to prevent bone loss after SCI and fractures are common. More research is required to define the pathophysiology and epidemiology of SCI-induced osteoporosis. This review summarizes emerging therapeutics including anti-sclerostin antibodies, mechanical loading of the lower extremity with electrical stimulation, and mechanical stimulation via vibration therapy. PMID:22983921

Effect of simulated weightlessness and chronic 1,25-dihydroxyvitamin D administration on bone metabolism

NASA Technical Reports Server (NTRS)

Halloran, B. P.; Bikle, D. D.; Globus, R. K.; Levens, M. J.; Wronski, T. J.; Morey-Holton, E.

1985-01-01

Weightlessness, as experienced during space flight, and simulated weightlessness induce osteopenia. Using the suspended rat model to simulate weightlessness, a reduction in total tibia Ca and bone formation rate at the tibiofibular junction as well as an inhibition of Ca-45 and H-3-proline uptake by bone within 5-7 days of skeletal unloading was observed. Between days 7 and 15 of unloading, uptake of Ca-45 and H-3-proline, and bone formation rate return to normal, although total bone Ca remains abnormally low. To examine the relationship between these characteristic changes in bone metabolism induced by skeletal unloading and vitamin D metabolism, the serum concentrations of 25-hydroxyvitamin D (25-OH-D), 24, 25-dihydroxyvitamin D (24,25(OH)2D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) at various times after skeletal unloading were measured. The effect of chronic infusion of 1,25(OH)2D3 on the bone changes associated with unloading was also determined.

Antagonists to TRPV1, ASICs and P2X have a potential role to prevent the triggering of regional bone metabolic disorder and pain-like behavior in tail-suspended mice.

PubMed

Hanaka, Megumi; Iba, Kousuke; Dohke, Takayuki; Kanaya, Kumiko; Okazaki, Shunichiro; Yamashita, Toshihiko

2018-05-01

Our recent studies demonstrated that regional bone loss in the unloaded hind limbs of tail-suspended mice triggered pain-like behaviors due to the acidic environment in the bone induced by osteoclast activation. The aims of the present study were to examine whether TRPV1, ASIC and P2X (known as nociceptors) are expressed in bone, and whether the antagonists to those receptors affect the expression of osteoblast and osteoclast regulators, and prevent the triggering of not only pain-like behaviors but also high bone turnover conditions in tail-suspension model mice. The hind limb-unloaded mice were subjected to tail suspension with the hind limbs elevated for 14days. The effects of the TRPV1, ASIC3, P2X2/3 antagonists on pain-like behaviors as assessed by the von Frey test, paw flick test and spontaneous pain scale; the expressions of TRPV1, ASICs, and P2X2 in the bone; and the effects of those antagonists on osteoblast and osteoclast regulators were examined. In addition, we evaluated the preventive effect of continuous treatment with a TRPV1 antagonist on the trigger for pain-like behavior and bone loss in tail-suspended mice. Pain-like behaviors were significantly improved by the treatment with TRPV1, ASIC, P2X antagonists; TRPV1, ASICs and P2X were expressed in the bone tissues; and the antagonists to these receptors down-regulated the expression of osteoblast and osteoclast regulators in tail-suspended mice. In addition, continuous treatment with a TRPV1 antagonist during tail-suspension prevented the induction of pain-like behaviors and regional bone loss in the unloaded hind limbs. We, therefore, believe that those receptor antagonists have a potential role in preventing the triggering of skeletal pain with associated regional bone metabolic disorder. Copyright © 2018 Elsevier Inc. All rights reserved.

Adaptation of the Skeletal System during Long-duration Spaceflight

NASA Technical Reports Server (NTRS)

Sibonga, Jean D.; Cavanagh, Peter R.; Lang, Thomas F.; LeBlanc, Adrian D.; Schneider, Victor S.; Shackelford, Linda C.; Smith, Scott M.; Vico, Laurence

2008-01-01

This review will highlight evidence from crew members flown on space missions greater than 90 days to suggest that the adaptations of the skeletal system to mechanical unloading may predispose crew members to an accelerated onset of osteoporosis after return to Earth. By definition, osteoporosis is a skeletal disorder - characterized by low bone mineral density and structural deterioration - that reduces the ability of bones to resist fracture under the loading of normal daily activities. Involutional or agerelated osteoporosis is readily recognized as a syndrome afflicting the elderly population because of the insipid and asymptomatic nature of bone loss that does not typically manifest as fractures until after age approximately 60. It is not the thesis of this review to suggest that spaceflight-induced bone loss is similar to bone loss induced by metabolic bone disease; rather this review draws parallels between the rapid and earlier loss in females that occurs with menopause and the rapid bone loss in middle-aged crew members that occurs with spaceflight unloading and how the cumulative effects of spaceflight and ageing could be detrimental, particularly if skeletal effects are totally or partially irreversible. In brief, this report will provide detailed evidence that long-duration crew members, exposed to the weightlessness of space for the typical long-duration (4-6 months) mission on Mir or the International Space Station -- 1. Display bone resorption that is aggressive, that targets normally weight-bearing skeletal sites, that is uncoupled to bone formation and that results in areal BMD deficits that can range between 6-20% of preflight BMD; 2. Display compartment-specific declines in volumetric BMD in the proximal femur (a skeletal site of clinical interest) that significantly reduces its compressive and bending strength and which may account for the loss in hip bone strength (i.e., force to failure); 3. Recover BMD over a post-flight time period that exceeds spaceflight exposure but for which the restoration of whole bone strength remains an open issue and may involve structural alteration; and 4. Display risk factors for bone loss -- such as the negative calcium balance and down-regulated calcium-regulating hormones in response to bone atrophy -- that can be compounded by the constraints of conducting mission operations (inability to provide essential nutrients and vitamins). The full characterization of the skeletal response to mechanical unloading in space is not complete. In particular, countermeasures used to date have been inadequate and it is not yet known whether more appropriate countermeasures can prevent the changes in bone that have been found in previous flights, knowledge gaps related to the effects of prolonged (greater than or equal to 6 months) space exposure and to partial gravity environments are substantial, and longitudinal measurements on crew members after spaceflight are required to assess the full impact on skeletal recovery.

Fractal dimension analysis of weight-bearing bones of rats during skeletal unloading

NASA Technical Reports Server (NTRS)

Pornprasertsuk, S.; Ludlow, J. B.; Webber, R. L.; Tyndall, D. A.; Sanhueza, A. I.; Yamauchi, M.

2001-01-01

Fractal analysis was used to quantify changes in trabecular bone induced through the use of a rat tail-suspension model to simulate microgravity-induced osteopenia. Fractal dimensions were estimated from digitized radiographs obtained from tail-suspended and ambulatory rats. Fifty 4-month-old male Sprague-Dawley rats were divided into groups of 24 ambulatory (control) and 26 suspended (test) animals. Rats of both groups were killed after periods of 1, 4, and 8 weeks. Femurs and tibiae were removed and radiographed with standard intraoral films and digitized using a flatbed scanner. Square regions of interest were cropped at proximal, middle, and distal areas of each bone. Fractal dimensions were estimated from slopes of regression lines fitted to circularly averaged plots of log power vs. log spatial frequency. The results showed that the computed fractal dimensions were significantly greater for images of trabecular bones from tail-suspended groups than for ambulatory groups (p < 0.01) at 1 week. Periods between 1 and 4 weeks likewise yielded significantly different estimates (p < 0.05), consistent with an increase in bone loss. In the tibiae, the proximal regions of the suspended group produced significantly greater fractal dimensions than other regions (p < 0.05), which suggests they were more susceptible to unloading. The data are consistent with other studies demonstrating osteopenia in microgravity environments and the regional response to skeletal unloading. Thus, fractal analysis could be a useful technique to evaluate the structural changes of bone.

Insulin-like growth factor-1 receptor in mature osteoblasts is required for periosteal bone formation induced by reloading

NASA Astrophysics Data System (ADS)

Kubota, Takuo; Elalieh, Hashem Z.; Saless, Neema; Fong, Chak; Wang, Yongmei; Babey, Muriel; Cheng, Zhiqiang; Bikle, Daniel D.

2013-11-01

Skeletal loading and unloading has a pronounced impact on bone remodeling, a process also regulated by insulin-like growth factor-1 (IGF-1) signaling. Skeletal unloading leads to resistance to the anabolic effect of IGF-1, while reloading after unloading restores responsiveness to IGF-1. However, a direct study of the importance of IGF-1 signaling in the skeletal response to mechanical loading remains to be tested. In this study, we assessed the skeletal response of osteoblast-specific Igf-1 receptor deficient (Igf-1r-/-) mice to unloading and reloading. The mice were hindlimb unloaded for 14 days and then reloaded for 16 days. Igf-1r-/- mice displayed smaller cortical bone and diminished periosteal and endosteal bone formation at baseline. Periosteal and endosteal bone formation decreased with unloading in Igf-1r+/+ mice. However, the recovery of periosteal bone formation with reloading was completely inhibited in Igf-1r-/- mice, although reloading-induced endosteal bone formation was not hampered. These changes in bone formation resulted in the abolishment of the expected increase in total cross-sectional area with reloading in Igf-1r-/- mice compared to the control mice. These results suggest that the Igf-1r in mature osteoblasts has a critical role in periosteal bone formation in the skeletal response to mechanical loading.

Skeletal unloading induces resistance to insulin-like growth factor I

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Harris, J.; Halloran, B. P.; Morey-Holton, E. R.

1994-01-01

In previous studies with a hindlimb elevation model, we demonstrated that skeletal unloading transiently inhibits bone formation. This effect is limited to the unloaded bones (the normally loaded humerus does not cease growing), suggesting that local factors are of prime importance. IGF-I is one such factor; it is produced in bone and stimulates bone formation. To determine the impact of skeletal unloading on IGF-I production and function, we assessed the mRNA levels of IGF-I and its receptor (IGF-IR) in the proximal tibia and distal femur of growing rats during 2 weeks of hindlimb elevation. The mRNA levels for IGF-I and IGF-IR rose during hindlimb elevation, returning toward control values during recovery. This was accompanied by a 77% increase in IGF-I levels in the bone, peaking at day 10 of unloading. Changes in IGF binding protein levels were not observed. Infusion of IGF-I (200 micrograms/day) during 1 week of hindlimb elevation doubled the increase in bone mass of the control animals but failed to reverse the cessation of bone growth in the hindlimb-elevated animals. We conclude that skeletal unloading induces resistance to IGF-I, which may result secondarily in increased local production of IGF-I.

Effect of excess dietary salt on calcium metabolism and bone mineral in a spaceflight rat model

NASA Technical Reports Server (NTRS)

Navidi, Meena; Wolinsky, Ira; Fung, Paul; Arnaud, Sara B.

1995-01-01

High levels of salt promote urinary calcium (UCa) loss and have the potential to cause bone mineral deficits if intestinal Ca absorption does not compensate for these losses. To determine the effect of excess dietary salt on the osteopenia that follows skeletal unloading, we used a spaceflight model that unloads the hindlimbs of 200-g rats by tail suspension (S). Rats were studied for 2 wk on diets containing high salt (4 and 8%) and normal calcium (0.45%) and for 4 wk on diets containing 8% salt (HiNa) and 0.2% Ca (LoCa). Final body weights were 9-11% lower in S than in control rats (C) in both experiments, reflecting lower growth rates in S than in C during pair feeding. UCa represented 12% of dietary Ca on HiNA diets and was twofold higher in S than in C transiently during unloading. Net intestinal Ca absorption was consistently 11-18% lower in S than in C. Serum 1,25-dihydroxyvitamin D was unaffected by either LoCa or HiNa diets in S but was increased by LoCa and HiNa diets in C. Despite depressed intestinal Ca absoption in S and a sluggish response of the Ca endocrine system to HiNa diets, UCa loss did not appear to affect the osteopenia induced by unloading. Although any deficit in bone mineral content from HiNa diets may have been too small to detect or the duration of the study too short to manifest, there were clear differences in Ca metabolism from control levels in the response of the spaceflight model to HiNa diets, indicated by depression of intestinal Ca absorption and its regulatory hormone.

The impact of skeletal unloading on bone formation

NASA Technical Reports Server (NTRS)

Bikle, Daniel D.; Sakata, Takeshi; Halloran, Bernard P.

2003-01-01

Skeletal unloading leads to decreased bone formation and decreased bone mass. Bone resorption is uncoupled from bone formation, contributing to the bone loss. During space flight bone is lost principally from the bones most loaded in the 1 g environment. Determining the mechanism(s) by which loading of bone is sensed and translated into a signal(s) controlling bone formation remains the holy grail in this field. It seems likely that matrix/cell interactions will underlie much of the mechanocoupling. Integrins are a prime mediator of such interactions. The role for systemic hormones such as PTH, GH and 1,25(OH)2D compared to locally produced factors such as IGF-I, PTHrP, BMPs and TGF beta in modulating the cellular response to load remains unclear. Our studies demonstrate that skeletal unloading leads to resistance to the anabolic actions of IGF-I on bone as a result of failure of IGF-I to activate its own signaling pathways. This is associated with a reduction in integrin expression, suggesting crosstalk between these two pathways. As the mechanism(s) by which bone responds to changes in mechanical load with changes in bone formation is further elucidated, applications of this knowledge to other etiologies of osteoporosis are likely to develop. Skeletal unloading provides a perturbation in bone mineral homeostasis that can be used to understand the mechanisms by which bone mineral homeostasis is maintained, and that such understanding will lead to effective treatment for disuse osteoporosis in addition to preventive measures for the bone loss that accompanies space travel.

Moderate tibia axial loading promotes discordant response of bone composition parameters and mechanical properties in a hindlimb unloading rat model.

PubMed

Yang, Peng-Fei; Huang, Ling-Wei; Nie, Xiao-Tong; Yang, Yue; Wang, Zhe; Ren, Li; Xu, Hui-Yun; Shang, Peng

2018-06-01

The purpose of the present study was to characterize the dynamic alterations of bone composition parameters and mechanical properties to disuse and mechanical intervention. A tail suspension hindlimb unloading model and an in vivo axial tibia loading model in rats were used. A moderate mechanical loading that was capable of engendering 800 µε tibia strain was applied to the right tibia of rats in both control and hindlimb unloading group across 28 days of the experimental period. The contralateral tibia served as control. Hindlimb unloading led to bone loss in tibia from day 14. Bone mineral density, mineral content and mechanical properties responded differently with microstructure to disuse in timing course. Mechanical loading of 800 µε tibia strain failed to alter the bone of the control group, but minimized the detrimental effects of unloading by completely prohibiting the decrease of bone mineral content and main mechanical properties after 28 days. Less obvious influence of mechanical loading on bone microstructure was found. The moderate mechanical loading is not able to stimulate the mechanical response of healthy tibia, but indeed lead to discordant recovery of bone composition parameters and mechanical properties.

Decreased Estrogen May Contribute to Osteopenia in Unloaded Bones

NASA Technical Reports Server (NTRS)

Tou, Janet; Arnaud, Sara; Grindeland, Richard; Wade, Charles

2004-01-01

Progressive loss of weight-bearing bone in astronauts is one of the most serious impediments to long-duration spaceflight. Estrogen deficiency in women is an established factor in bone loss. Reduced sex hormone levels have been reported in male astronauts, but no data is available regarding spaceflight effects on female sex hormones. The objective of our study was to determine the role of estrogen in disuse osteopenia. The NASA developed hindlimb suspension (HLS) model was used to simulate the unloading disuse of weight-bearing bones experienced in space. Female Sprague-Dawley rats (age 77d; n = 20/group) were HLS or kept ambulatory (AMB) for 38 d and endocrine and bone indices determined. HLS of rats resulted in lower (p less than 0.01) bone mass (9%0), bone mineral content (BMC 13%) and mechanical strength (28%) compared to AMB animals. Plasma estradiol (E2) was lower (p = 0.03) in HLS (10.1 +/- 1.4 pg/ml) compared to AMB rats (16.7 +/- 2.6 pg/ml). E2 was positively correlated to BMC r(sup 2) = 0.67 and mechanical strength r(sup 2) = 0.61. These results suggest that reduced E2 plays a role in disuse osteopenia induced by HLS. Plasma or pituitary lutenizing hormone (LH) and follicle stimulating hormone (FSH) levels were not different in HLS versus AMB rats. However, pituitary LH was correlated to E2 (r(sup 2) = 0.57), suggesting changes in E2 were exerted at the level of the hypothalamus-pituitary axis. Understanding the role of estrogen in disuse osteopenia is necessary to the development of efficacious therapies for female astronauts, bed rest patients and the increasing number of individuals in our sedentary population suffering bone loss.

Simulated weightlessness and synbiotic diet effects on rat bone mechanical strength

NASA Astrophysics Data System (ADS)

Sarper, Hüseyin; Blanton, Cynthia; DePalma, Jude; Melnykov, Igor V.; Gabaldón, Annette M.

2014-10-01

This paper reports results on exposure to simulated weightlessness that leads to a rapid decrease in bone mineral density known as spaceflight osteopenia by evaluating the effectiveness of dietary supplementation with synbiotics to counteract the effects of skeletal unloading. Forty adult male rats were studied under four different conditions in a 2 × 2 factorial design with main effects of diet (synbiotic and control) and weight condition (unloaded and control). Hindlimb unloading was performed at all times for 14 days followed by 14 days of recovery (reambulation). The synbiotic diet contained probiotic strains Lactobacillus acidophilus and Lactococcus lactis lactis and prebiotic fructooligosaccharide. This paper also reports on the development of a desktop three-point bending device to measure the mechanical strength of bones from rats subjected to simulated weightlessness. The importance of quantifying bone resistance to breakage is critical when examining the effectiveness of interventions against osteopenia resulting from skeletal unloading, such as astronauts experience, disuse or disease. Mechanical strength indices provide information beyond measures of bone density and microarchitecture that enhance the overall assessment of a treatment's potency. In this study we used a newly constructed three-point bending device to measure the mechanical strength of femur and tibia bones from hindlimb-unloaded rats fed an experimental synbiotic diet enriched with probiotics and fermentable fiber. Two calculated outputs for each sample were Young's modulus of elasticity and fracture stress. Bone major elements (calcium, magnesium, and phosphorous) were quantified using ICP-MS analysis. Hindlimb unloading was associated with a significant loss of strength in the femur, and with significant reductions in major bone elements. The synbiotic diet did not protect against these unloading effects. Tibia strength and major elements were not reduced by hindlimb unloading, as was the case for femur, but tibia bone strength was negatively affected by the synbiotic diet. Thus, unexpectedly, the synbiotic diet was associated with null or detrimental effects on bone strength.

High Salt Diets, Bone Strength and Mineral Content of Mature Femur After Skeletal Unloading

NASA Technical Reports Server (NTRS)

Liang, Michael T. C.

1998-01-01

It is known that high salt diets increase urinary calcium (Ca) loss, but it is not known whether this effect weakens bone during space flight. The Bone Hormone Lab has studied the effect of high salt diets on Ca balance and whole body Ca in a space flight model (2,8). Neither the strength nor mineral content of the femurs from these studies has been evaluated. The purpose of this study was to determine the effect of high salt diets (HiNa) and skeletal unloading on femoral bone strength and bone mineral content (BMC) in mature rats.

Increasing the number of unloading/reambulation cycles does not adversely impact body composition and lumbar bone mineral density but reduces tissue sensitivity

NASA Astrophysics Data System (ADS)

Gupta, Shikha; Manske, Sarah L.; Judex, Stefan

2013-11-01

A single exposure to hindlimb unloading leads to changes in body mass, body composition and bone, but the consequences of multiple exposures are not yet understood. Within a 18 week period, adult C57BL/6 male mice were exposed to 1 (1x-HLU), 2 (2x-HLU) or 3 (3x-HLU) cycles of 2 weeks of hindlimb unloading (HLU) followed by 4 weeks of reambulation (RA), or served as ambulatory age-matched controls. In vivo μCT longitudinally tracked changes in abdominal adipose and lean tissues, lumbar vertebral apparent volumetric bone mineral density (vBMD) and upper hindlimb muscle cross-sectional area before and after the final HLU and RA cycle. During the final HLU cycle, significant decreases in total adipose tissue and vertebral vBMD in the three experimental groups occurred such that there were no significant between-group differences at the beginning of the final RA cycle. However, the magnitude of the HLU induced losses diminished in mice undergoing their 2nd or 3rd HLU cycle. Irrespective of the number of HLU/RA cycles, total adipose tissue and vertebral vBMD recovered and were no different from age-matched controls after the final RA period. In contrast, upper hindlimb muscle cross-sectional area was significantly lower than controls in all unloaded groups after the final RA period. These results suggest that tissues in the abdominal region are more resilient to multiple bouts of unloading and more amenable to recovery during reambulation than the peripheral musculoskeletal system.

Vitamin E provides protection for bone in mature hindlimb unloaded male rats

NASA Technical Reports Server (NTRS)

Smith, B. J.; Lucas, E. A.; Turner, R. T.; Evans, G. L.; Lerner, M. R.; Brackett, D. J.; Stoecker, B. J.; Arjmandi, B. H.

2005-01-01

The deleterious effects of skeletal unloading on bone mass and strength may, in part, result from increased production of oxygen-derived free radicals and proinflammatory cytokines. This study was designed to evaluate the ability of vitamin E (alpha-tocopherol), a free-radical scavenger with antiinflammatory properties, to protect against bone loss caused by skeletal unloading in mature male Sprague-Dawley rats. A 2 x 3 factorial design was used with either hindlimb unloading (HU) or normal loading (ambulatory; AMB), and low-dose (LD; 15 IU/kg diet), adequate-dose (AD; 75 IU/kg diet), or high-dose (HD; 500 IU/kg diet) vitamin E (DL-alpha-tocopherol acetate). To optimize the effects of vitamin E on bone, dietary treatments were initiated 9 weeks prior to unloading and continued during the 4-week unloading period, at which time animals were euthanized and blood and tissue samples were collected. Serum vitamin E was dose-dependently increased, confirming the vitamin E status of animals. The HD treatment improved oxidation parameters, as indicated by elevated serum ferric-reducing ability and a trend toward reducing tissue lipid peroxidation. Histomorphometric analysis of the distal femur revealed significant reductions in trabecular thickness (TbTh), double-labeled surface (dLS/BS), and rate of bone formation to bone volume (BFR/BV) due by HU. AMB animals on the HD diet and HU animals on the LD diet had reduced bone surface normalized to tissue volume (BS/TV) and trabecular number (TbN); however, the HD vitamin E protected against these changes in the HU animals. Our findings suggest that vitamin E supplementation provides modest bone protective effects during skeletal unloading.

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

NASA Technical Reports Server (NTRS)

Alwood, J. S.; Limoli, C. L.; Delp, M. D.; Castillo, A. B.; Globus, R. K.

2012-01-01

Weightlessness causes a cephalad fluid shift and reduction in mechanical stimulation, adversely affecting both cortical and trabecular bone tissue in astronauts. In rodent models of weightlessness, the onset of bone loss correlates with reduced skeletal perfusion, reduced and rarified vasculature and lessened vasodilation, which resembles blood-bone symbiotic events that can occur with fracture repair and aging. These are especially serious risks for long term, exploration class missions when astronauts will face the challenge of increased exposure to space radiation and abrupt transitions between different gravity environments upon arrival and return. Previously, we found using the mouse hindlimb unloading model and exposure to heavy ion radiation, both disuse and irradiation cause an acute bone loss that was associated with a reduced capacity to produce bone-forming osteoblasts from the bone marrow. Together, these findings led us to hypothesize that exposure to space radiation exacerbates weightlessness-induced bone loss and impairs recovery upon return, and that treatment with anti-oxidants may mitigate these effects. The specific aims of this recently awarded grant are to: AIM 1 Determine the functional and structural consequences of prolonged weightlessness and space radiation (simulated spaceflight) for bone and skeletal vasculature in the context of bone cell function and oxidative stress. AIM 2 Determine the extent to which an anti-oxidant protects against weightlessness and space radiation-induced bone loss and vascular dysfunction. AIM 3 Determine how space radiation influences later skeletal and vasculature recovery from prolonged weightlessness and the potential of anti-oxidants to preserve adaptive remodeling.

Contributions of Severe Burn and Disuse to Bone Structure and Strength in Rats

PubMed Central

Baer, L.A.; Wu, X.; Tou, J. C.; Johnson, E.; Wolf, S.E.; Wade, C.E.

2012-01-01

Burn and disuse results in metabolic and bone changes associated with substantial and sustained bone loss. Such loss can lead to an increased fracture incidence and osteopenia. We studied the independent effects of burn and disuse on bone morphology, composition and strength, and microstructure of the bone alterations 14 days after injury. Sprague-Dawley rats were randomized into four groups: Sham/Ambulatory (SA), Burn/Ambulatory (BA), Sham/Hindlimb Unloaded (SH) and Burn/Hindlimb Unloaded (BH). Burn groups received a 40% total body surface area full-thickness scald burn. Disuse by hindlimb unloading was initiated immediately following injury. Bone turnover was determined in plasma and urine. Femur biomechanical parameters were measured by three-point bending tests and bone microarchitecture was determined by microcomputed tomography (uCT). On day 14, a significant reduction in body mass was observed as a result of burn, disuse and a combination of both. In terms of bone health, disuse alone and in combination affected femur weight, length and bone mineral content. Bending failure energy, an index of femur strength, was significantly reduced in all groups and maximum bending stress was lower when burn and disuse were combined. Osteocalcin was reduced in BA compared to the other groups, indicating influence of burn. The reductions observed in femur weight, BMC, biomechanical parameters and indices of bone formation are primarily responses to the combination of burn and disuse. These results offer insight into bone degradation following severe injury and disuse. PMID:23142361

Skeletal unloading inhibits the in vitro proliferation and differentiation of rat osteoprogenitor cells

NASA Technical Reports Server (NTRS)

Kostenuik, P. J.; Halloran, B. P.; Morey-Holton, E. R.; Bikle, D. D.

1997-01-01

Loss of weight bearing in the growing rat decreases bone formation, osteoblast numbers, and bone maturation in unloaded bones. These responses suggest an impairment of osteoblast proliferation and differentiation. To test this assumption, we assessed the effects of skeletal unloading using an in vitro model of osteoprogenitor cell differentiation. Rats were hindlimb elevated for 0 (control), 2, or 5 days, after which their tibial bone marrow stromal cells (BMSCs) were harvested and cultured. Five days of hindlimb elevation led to significant decreases in proliferation, alkaline phosphatase (AP) enzyme activity, and mineralization of BMSC cultures. Differentiation of BMSCs was analyzed by quantitative competitive polymerase chain reaction of cDNA after 10, 15, 20, and 28 days of culture. cDNA pools were analyzed for the expression of c-fos (an index of proliferation), AP (an index of early osteoblast differentiation), and osteocalcin (a marker of late differentiation). BMSCs from 5-day unloaded rats expressed 50% less c-fos, 61% more AP, and 35% less osteocalcin mRNA compared with controls. These data demonstrate that cultured osteoprogenitor cells retain a memory of their in vivo loading history and indicate that skeletal unloading inhibits proliferation and differentiation of osteoprogenitor cells in vitro.

Mechanical stimulation promote the osteogenic differentiation of bone marrow stromal cells through epigenetic regulation of Sonic Hedgehog.

PubMed

Wang, Chuandong; Shan, Shengzhou; Wang, Chenglong; Wang, Jing; Li, Jiao; Hu, Guoli; Dai, Kerong; Li, Qingfeng; Zhang, Xiaoling

2017-03-15

Mechanical unloading leads to bone loss and disuse osteoporosis partly due to impaired osteoblastogenesis of bone marrow stromal cells (BMSCs). However, the underlying molecular mechanisms of this phenomenon are not fully understood. In this study, we demonstrated that cyclic mechanical stretch (CMS) promotes osteoblastogenesis of BMSCs both in vivo and in vitro. Besides, we found that Hedgehog (Hh) signaling pathway was activated in this process. Inhibition of which by either knockdown of Sonic hedgehog (Shh) or treating BMSCs with Hh inhibitors attenuated the osteogenic effect of CMS on BMSCs, suggesting that Hh signaling pathway acts as an endogenous mediator of mechanical stimuli on BMSCs. Furthermore, we demonstrated that Shh expression level was regulated by DNA methylation mechanism. Chromatin Immunoprecipitation (ChIP) assay showed that DNA methyltransferase 3b (Dnmt3b) binds to Shh gene promoter, leading to DNA hypermethylation in mechanical unloading BMSCs. However, mechanical stimulation down-regulates the protein level of Dnmt3b, results in DNA demethylation and Shh expression. More importantly, we found that inhibition of Dnmt3b partly rescued bone loss in HU mice by mechanical unloading. Our results demonstrate, for the first time, that mechanical stimulation regulates osteoblastic genes expression via direct regulation of Dnmt3b, and the therapeutic inhibition of Dnmt3b may be an efficient strategy for enhancing bone formation under mechanical unloading. Copyright © 2017 Elsevier Inc. All rights reserved.

Local vibration enhanced the efficacy of passive exercise on mitigating bone loss in hindlimb unloading rats

NASA Astrophysics Data System (ADS)

Huang, Yunfei; Luan, Huiqin; Sun, Lianwen; Bi, Jingfang; Wang, Ying; Fan, Yubo

2017-08-01

Spaceflight induced bone loss is seriously affecting astronauts. Mechanical stimulation from exercise has been shown to restrain bone resorption as well as improve bone formation. Current exercise countermeasures in space cannot prevent it completely. Active exercise may convert to passive exercise in some ways because of the loss of gravity stimulus and inertia of exercise equipment. The aim of this study was to compare the efficacy of passive exercise or/and local vibration on counteracting the deterioration of the musculoskeletal system, including bone, muscle and tendons in tail-suspended rats. We hypothesized that local vibration could enhance the efficacy of passive exercise on countering bone loss. 40 Sprague Dawley rats were randomly distributed into five groups (n = 8, each): tail-suspension (TS), TS+35 Hz vibration (TSV), TS + passive exercise (TSP), TS + passive exercise coupled with 35 Hz vibration (TSPV) and control (CON). Passive exercise or/and local vibration was performed for 21 days. On day 0 and 21, bone mineral density (BMD) was observed by dual energy X-ray absorptiometry (DXA), and trabecular microstructure was evaluated by microcomputer tomography (μCT) analysis in vivo. Mechanical properties of tibia and tendon were determined by a mechanical testing system. Soleus and bone ash weight was tested by an electronic balance. Results showed that the passive exercise could not prevent the decrease of trabecular BMD, microstructure and bone ash weight induced by TS, whereas vibration and passive exercise coupled with local vibration (PV) could. Biomechanical properties of the tibia and tendon in TSPV group significantly increased compared with TS group. In summary, PV in this study was the best method in preventing weightlessness-induced bone loss. Consistent with our hypothesis, local vibration partly enhanced the effect of passive exercise. Furthermore, this study will be useful in improving countermeasure for astronauts, but also for the rehabilitation of disused or aged osteoporosis.

Bone Metabolism after Bariatric Surgery

PubMed Central

Yu, Elaine W.

2014-01-01

Bariatric surgery is a popular and effective treatment for severe obesity, but may have negative effects on the skeleton. This review summarizes changes in bone density and bone metabolism from animal and clinical studies of bariatric surgery, with specific attention to Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG). Skeletal imaging artifacts from obesity and weight loss are also considered. Despite challenges in bone density imaging, the preponderance of evidence suggests that bariatric surgery procedures have negative skeletal effects that persist beyond the first year of surgery, and that these effects vary by surgical type. The long-term clinical implications and current clinical recommendations are presented. Further study is required to determine mechanisms of bone loss after bariatric surgery. Although early studies focused on calcium/vitamin D metabolism and mechanical unloading of the skeleton, it seems likely that surgically-induced changes in the hormonal and metabolic profile may be responsible for the skeletal phenotypes observed after bariatric surgery. PMID:24677277

The response of bone to unloading

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Halloran, B. P.

1999-01-01

Skeletal unloading leads to decreased bone formation and decreased bone mass. Bone resorption is uncoupled from bone formation, contributing to the bone loss. During spaceflight bone is lost principally from the bones most loaded in the 1-g environment, and some redistribution of bone from the lower extremities to the head appears to take place. Although changes in calcitropic hormones have been demonstrated during skeletal unloading (PTH and 1,25(OH)2D decrease), it remains unclear whether such changes account for or are in response to the changes in bone formation and resorption. Bed rest studies with human volunteers and hindlimb elevation studies with rats have provided useful data to help explain the changes in bone formation during spaceflight. These models of skeletal unloading reproduce a number of the conditions associated with microgravity, and the findings from such studies confirm many of the observations made during spaceflight. Determining the mechanism(s) by which loading of bone is sensed and translated into a signal(s) controlling bone formation remains the holy grail in this field. Such investigations couple biophysics to biochemistry to cell and molecular biology. Although studies with cell cultures have revealed biochemical responses to mechanical loads comparable to that seen in intact bone, it seems likely that matrix-cell interactions underlie much of the mechanocoupling. The role for systemic hormones such as PTH, GH, and 1,25(OH)2D compared to locally produced factors such as IGF-I, PTHrP, BMPs, and TGF-beta in modulating the cellular response to load remains unclear. As the mechanism(s) by which bone responds to mechanical load with increased bone formation are further elucidated, applications of this knowledge to other etiologies of osteoporosis are likely to develop. Skeletal unloading provides a perturbation in bone mineral homeostasis that can be used to understand the mechanisms by which bone mineral homeostasis is maintained, with the expectation that such understanding will lead to effective treatment for disuse osteoporosis.

Disuse exaggerates the detrimental effects of alcohol on cortical bone

NASA Technical Reports Server (NTRS)

Hefferan, Theresa E.; Kennedy, Angela M.; Evans, Glenda L.; Turner, Russell T.

2003-01-01

BACKGROUND: Alcohol abuse is associated with an increased risk for osteoporosis. However, comorbidity factors may play an important role in the pathogenesis of alcohol-related bone fractures. Suboptimal mechanical loading of the skeleton, an established risk factor for bone loss, may occur in some alcohol abusers due to reduced physical activity, muscle atrophy, or both. The effect of alcohol consumption and reduced physical activity on bone metabolism has not been well studied. The purpose of this study was to determine whether mechanical disuse alters bone metabolism in a rat model for chronic alcohol abuse. METHODS: Alcohol was administered in the diet (35% caloric intake) of 6-month-old male rats for 4 weeks. Rats were hindlimb-unloaded the final 2 weeks of the experiment to prevent dynamic weight bearing. Afterward, cortical bone histomorphometry was evaluated at the tibia-fibula synostosis. RESULTS: At the periosteal surface of the tibial diaphysis, alcohol and hindlimb unloading independently decreased the mineralizing perimeter, mineral apposition rate, and bone formation rate. In addition, alcohol, but not hindlimb unloading, increased endocortical bone resorption. The respective detrimental effects of alcohol and hindlimb unloading to inhibit bone formation were additive; there was no interaction between the two variables. CONCLUSIONS: Reduced weight bearing accentuates the detrimental effects of alcohol on cortical bone in adult male rats by further inhibiting bone formation. This finding suggests that reduced physical activity may be a comorbidity factor for osteoporosis in alcohol abusers.

A Computational Model for Simulating Spaceflight Induced Bone Remodeling

NASA Technical Reports Server (NTRS)

Pennline, James A.; Mulugeta, Lealem

2014-01-01

An overview of an initial development of a model of bone loss due to skeletal unloading in weight bearing sites is presented. The skeletal site chosen for the initial application of the model is the femoral neck region because hip fractures can be debilitating to the overall performance health of astronauts. The paper begins with the motivation for developing such a model of the time course of change in bone in order to understand the mechanism of bone demineralization experienced by astronauts in microgravity, to quantify the health risk, and to establish countermeasures. Following this, a general description of a mathematical formulation of the process of bone remodeling is discussed. Equations governing the rate of change of mineralized bone volume fraction and active osteoclast and osteoblast are illustrated. Some of the physiology of bone remodeling, the theory of how imbalance in remodeling can cause bone loss, and how the model attempts to capture this is discussed. The results of a preliminary validation analysis that was carried out are presented. The analysis compares a set of simulation results against bone loss data from control subjects who participated in two different bed rest studies. Finally, the paper concludes with outlining the current limitations and caveats of the model, and planned future work to enhance the state of the model.

Computational Analysis of Artificial Gravity as a Possible Countermeasure to Spaceflight Induced Bone Loss

NASA Technical Reports Server (NTRS)

Mulugeta, L.; Werner, C. R.; Pennline, J. A.

2015-01-01

During exploration class missions, such as to asteroids and Mars, astronauts will be exposed to reduced gravity for extended periods. Data has shown that astronauts lose bone mass at a rate of 1% to 2% a month in microgravity, particularly in lower extremities such as the proximal femur. Exercise countermeasures have not completely eliminated bone loss from long duration spaceflight missions, which leaves astronauts susceptible to early onset osteoporosis and greater risk of fracture. Introduction of the Advanced Resistive Exercise Device and other large exercise devices on the International Space Station (ISS), coupled with improved nutrition, has further minimized bone loss. However, unlike the ISS, exploration vehicles will have very limited volume and power available to accommodate such capabilities. Therefore, novel concepts like artificial gravity systems are being explored as a means to provide sufficient load stimulus to the musculoskeletal system to mitigate bone changes that may lead to early onset osteoporosis and increased risk of fracture. Currently, there is minimal data available to drive further research and development efforts to appropriately explore such options. Computational modeling can be leveraged to gain insight on the level of osteoprotection that may be achieved using artificial gravity produced by a spinning spacecraft or centrifuge. With this in mind, NASA's Digital Astronaut Project (DAP) has developed a bone remodeling model that has been validated for predicting volumetric bone mineral density (vBMD) changes of trabecular and cortical bone both for gravitational unloading condition and the equivalent of 1g daily load stimulus. Using this model, it is possible to simulate vBMD changes in trabecular and cortical bone under different gravity conditions. In this presentation, we will discuss our preliminary findings regarding if and how artificial gravity may be used to mitigate spaceflight induced bone loss.

Skeletal unloading causes resistance of osteoprogenitor cells to parathyroid hormone and to insulin-like growth factor-I

NASA Technical Reports Server (NTRS)

Kostenuik, P. J.; Harris, J.; Halloran, B. P.; Turner, R. T.; Morey-Holton, E. R.; Bikle, D. D.

1999-01-01

Skeletal unloading decreases bone formation and osteoblast number in vivo and decreases the number and proliferation of bone marrow osteoprogenitor (BMOp) cells in vitro. We tested the ability of parathyroid hormone (PTH) to stimulate BMOp cells in vivo by treating Sprague Dawley rats (n = 32) with intermittent PTH(1-34) (1 h/day at 8 microg/100 g of body weight), or with vehicle via osmotic minipumps during 7 days of normal weight bearing or hind limb unloading. Marrow cells were flushed from the femur and cultured at the same initial density for up to 21 days. PTH treatment of normally loaded rats caused a 2.5-fold increase in the number of BMOp cells, with similar increases in alkaline phosphatase (ALP) activity and mineralization, compared with cultures from vehicle-treated rats. PTH treatment of hind limb unloaded rats failed to stimulate BMOp cell number, ALP activity, or mineralization. Hind limb unloading had no significant effect on PTH receptor mRNA or protein levels in the tibia. Direct in vitro PTH challenge of BMOp cells isolated from normally loaded bone failed to stimulate their proliferation and inhibited their differentiation, suggesting that the in vivo anabolic effect of intermittent PTH on BMOp cells was mediated indirectly by a PTH-induced factor. We hypothesize that this factor is insulin-like growth factor-I (IGF-I), which stimulated the in vitro proliferation and differentiation of BMOp cells isolated from normally loaded bone, but not from unloaded bone. These results suggest that IGF-I mediates the ability of PTH to stimulate BMOp cell proliferation in normally loaded bone, and that BMOp cells in unloaded bone are resistant to the anabolic effect of intermittent PTH therapy due to their resistance to IGF-I.

The Effect of Skeletal Unloading on Bone Formation: Role of IGF-I

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Kostenuik, P.; Holton, E. M.; Halloran, B. P.

1999-01-01

The best documented change in bone during space flight is the near cessation of bone formation. Space flight leads to a decrease in osteoblast number and activity, likely the result of altered differentiation of osteoblast precursors. The net result of these space flight induced changes is weaker bone. To understand the mechanism for these changes poses a challenge. Space flight studies must overcome enormous technical problems, and are necessarily limited in size and frequency. Therefore, ground based models have been developed to evaluate the effects of skeletal unloading. The hindlimb elevation (tail suspension) model simulates space flight better than other models because it reproduces the fluid shifts seen in space travel, is reversible, and is well tolerated by the animals with minimal evidence of stress as indicated by continued weight gain and normal levels and circadian rhythms of corticosterone. This is the model we have used for our experiments. Skeletal unloading by the hindlimb elevation method simulates a number of features of space flight in that bone formation, mineralization, and maturation are inhibited, osteoblast number is decreased, serum and skeletal osteocalcin levels fall, the ash content of bone decreases, and bone strength diminishes. We and others have shown that when osteoblasts or osteoprogenitor cells from the bones of the unloaded limbs are cultured in vitro they proliferate and differentiate more slowly, suggesting that skeletal unloading causes a persistent change in cell function which can be assessed in vitro. In contrast to the unweighted bones of the hindlimbs, no significant change in bone mass or bone formation is observed in the humeri, mandible, and cervical vertebrae during hindlimb elevation. The lack of effect of hindlimb elevation on bones like the humeri, mandible, and cervical vertebrae which are not unloaded by this procedure suggests that local factors rather than systemic effects dominate the response of bone to skeletal unloading. We have focussed on the role of IGF- 1 as the local factor mediating the effects of skeletal unloading on bone formation. IGF-I is produced by bone cells and chondrocytes; these cells have receptors for IGF-I, and respond to IGF-I with an increase in proliferation and function (e.g. collagen, and glycosaminoglycan production, respectively). IGF-I production by bone is under hormonal control, principally by GH and PTH, and IGF-I is thought to mediate some if not all of the effects of GH and PTH on bone growth. Thus, systemic changes in hormones such as GH and PTH may still have effects which vary from bone to bone depending on the loading history.

Bisphosphonate effects in rat unloaded hindlimb bone loss model: three-dimensional microcomputed tomographic, histomorphometric, and densitometric analyses.

PubMed

Barou, O; Lafage-Proust, M H; Martel, C; Thomas, T; Tirode, F; Laroche, N; Barbier, A; Alexandre, C; Vico, L

1999-10-01

The effects of antiresorptive drugs on bone loss remain unclear. Using three-dimensional microtomography, dual X-ray/densitometry, and histomorphometry, we evaluated tiludronate effects in the bone loss model of immobilization in tail-suspended rats after 7, 13, and 23 days. Seventy-eight 12-week-old Wistar male rats were assigned to 13 groups: 1 baseline group, and for each time point, 1 control group treated with vehicle and three tail-suspended groups treated with either tiludronate (0.5 or 5 mg/kg) or vehicle, administered s. c. every other day, during the last week before sacrifice. In primary spongiosa (ISP), immobilization-induced bone loss plateaued after day 7 and was prevented by tiludronate. In secondary spongiosa (IISP), bone loss appeared at day 13 with a decrease in trabecular thickness and trabecular number (Tb.N) as assessed by three-dimensional microtomography. Osteoclastic parameters did not differ in tail-suspended rats versus control rats, whereas bone formation showed a biphasic pattern: after a marked decrease at day 7, osteoblastic activity and recruitment normalized at days 13 and 23, respectively. At day 23, the 80% decrease in bone mass was fully prevented by high-dose tiludronate with an increase in Tb.N without preventing trabecular thinning. In summary, at day 7, tiludronate prevented bone loss in ISP. After day 13, tiludronate prevented bone loss in ISP and IISP despite a further decrease in bone formation. Thus, the preventive effects of tiludronate in this model may be related to the alteration in bone modeling with an increase in Tb.N in ISP and subsequently in IISP.

Skeletal unloading and dietary copper depletion are detrimental to bone quality of mature rats

NASA Technical Reports Server (NTRS)

Smith, Brenda J.; King, Jarrod B.; Lucas, Edralin A.; Akhter, Mohammed P.; Arjmandi, Bahram H.; Stoecker, Barbara J.

2002-01-01

This study was designed to examine the skeletal response to copper depletion and mechanical unloading in mature animals. In a 2 x 2 experimental design, 5.5-mo-old male Sprague-Dawley rats (n = 36) consumed either the control (AIN-93M) or Cu-depletion ((-)Cu) diet beginning 21 d before suspension and throughout the remainder of the study. Half of the rats in each dietary treatment group were either tail-suspended (TS) or kept ambulatory (AMB) for 28 d. Lower bone mineral densities (BMD) of 5th lumbar vertebra (L5) (P < 0.05) and femur were observed with (-)Cu and TS, but no differences were noted in the BMD of the humerus. Mechanical strength in the femur and vertebra decreased in response to TS, but were unaffected by copper depletion. Urinary deoxypyridinoline, an index of bone resorption, was significantly greater in TS rats, but unaltered by (-)Cu. No changes in serum or bone alkaline phosphatase activity, an indicator of bone formation, were observed. Our findings suggest that TS and (-)Cu decreased BMD in unloaded femur and vertebra but had no effect on normally loaded humerus. Bone loss with TS appeared to be related to accelerated bone resorption. Alterations in bone metabolism and bone mechanical properties in the mature skeleton resulting from (-)Cu warrant further investigation.

Simulated Microgravity Induces SOST/Sclerostin Upregulation in Osteocytes

NASA Technical Reports Server (NTRS)

Spatz, Jordan; Sibonga, Jean; Wu, Honglu; Barry, Kevin; Bouxsein, Mary; Pajevic, Paola Divieti

2010-01-01

Osteocytes are theorized to be the mechanosensors and transducers of mechanical forces in bone, yet the biological mechanism of this action remains elusive. Recent evidence suggests that SOST/Sclerostin is an important regulator of mechano-transduction. To investigate the molecular mechanisms of SOST/Sclerostin regulation under in-vitro and ex-vivo unloading we used the NASA Rotating Wall Vessel(RWV) Bioreactor. For in-vitro experiments, MLOY-4 osteocytic cells were seeded at a concentration of 250,000 cells onto 3D collagen scaffold (BD). Scaffolds (4 per condition) were either rotated in a vertical 50ml NASA/bioreactor vessel at 18 rpm (unloaded), cultured in a horizontal 50 ml NASA bioreactor vessel at 18 rpm (control for the sheared environment of vertical rotating vessel), or cultured in a static T-75 cm dish (static condition ) for 7days. For ex-vivo experiments, calvaria bones were harvested from 12-week old C57/Bl6 mice and sequentially digested with type I/II collagenase to remove periosteal osteoblasts. Calvaria halves (10 per condition) were then exposed to the same set of culture conditions described above. Simulated unloading, as achieved in the NASA RWV, resulted in enlarged, round osteocytes, as assessed by H&E staining, that was reminiscent of prior reports of unloading causing loss of osteocyte morphology and dendritic network connectivity. Semiquantitative realtime qPCR and immunohistochemistry from both in-vitro and ex-vivo RWV experiments demonstrated a four-fold up-regulation of SOST/Sclerostin. Furthermore, mRNA of the transcriptional SOST enhancer Mef2C was upregulated 1.4 fold in ex-vivo calvaria subjected to unloading conditions of the NASA RWV, suggesting that Mef2C might be an important regulator of mechano-sensation. These findings are consistent with results from seven day hindlimb unloading experiments, C57/B6 females, conducted in our laboratory and validate the use of the NASA RWV as a tool to study osteocyte mechanotransduction

Circulating sclerostin is elevated in short-term and reduced in long-term SCI

PubMed Central

Battaglino, Ricardo A.; Sudhakar, Supreetha; Lazzari, Antonio; Garshick, Eric; Zafonte, Ross; Morse, Leslie R.

2012-01-01

Spinal cord injury (SCI) causes profound bone loss due to muscle paralysis resulting in the inability to walk. Sclerostin, a Wnt signaling pathway antagonist produced by osteocytes, is a potent inhibitor of bone formation. Short-term studies in rodent models have demonstrated increased sclerostin in response to mechanical unloading that is reversed with reloading. Although sclerostin inhibition has been proposed as a potential therapy for bone loss, it is not known if sclerostin levels vary with duration of SCI in humans. We analyzed circulating sclerostin in 155 men with varying degrees of SCI who were 1 year or more post-injury. We report that sclerostin levels are greatest in subjects with short-term SCI (≤ 5 years post-injury) and decrease significantly over the first 5 years post-injury. There was no association between sclerostin and injury duration in subjects with long-term SCI (> 5 years post-injury). In subjects with long-term SCI, sclerostin levels were positively associated with lower extremity bone density and bone mineral content. These data suggest that sclerostin levels in SCI are initially increased after SCI in response to mechanical unloading. This response is time-limited and as bone loss progresses, circulating sclerostin is lowest in subjects with severe osteoporosis. These findings support a dual role for sclerostin after SCI: a therapeutic target in acute SCI, and a biomarker of osteoporosis severity in chronic SCI. PMID:22575440

Site- and compartment-specific changes in bone with hindlimb unloading in mature adult rats

NASA Technical Reports Server (NTRS)

Bloomfield, S. A.; Allen, M. R.; Hogan, H. A.; Delp, M. D.

2002-01-01

The purpose of this study was to examine site- and compartment-specific changes in bone induced by hindlimb unloading (HU) in the mature adult male rat (6 months old). Tibiae, femora, and humeri were removed after 14, 21, and 28 days of HU for determination of bone mineral density (BMD) and geometry by peripheral quantitative computed tomography (pQCT), mechanical properties, and bone formation rate (BFR), and compared with baseline (0 day) and aging (28 day) controls. HU resulted in 20%-21% declines in cancellous BMD at the proximal tibia and femoral neck after 28 day HU vs. 0 day controls (CON). Cortical shell BMD at these sites was greater (by 4%-6%) in both 28 day HU and 28 day CON vs. 0 day CON animals, and nearly identical to that gain seen in the weight-bearing humerus. Mechanical properties at the proximal tibia exhibited a nonsignificant decline after HU vs. those of 0 day CON rats. At the femoral neck, a 10% decrement was noted in ultimate load in 28 day HU rats vs. 28 day CON animals. Middiaphyseal tibial bone increased slightly in density and area during HU; no differences in structural and material properties between 28 day HU and 28 day CON rats were noted. BFR at the tibial midshaft was significantly lower (by 90%) after 21 day HU vs. 0 day CON; this decline was maintained throughout 28 day HU. These results suggest there are compartment-specific differences in the mature adult skeletal response to hindlimb unloading, and that the major impact over 28 days of unloading is on cancellous bone sites. Given the sharp decline in BFR for midshaft cortical bone, it appears likely that deficits in BMD, area, or mechanical properties would develop with longer duration unloading.

Suppression of osteoblastic phenotypes and modulation of pro- and anti-apoptotic features in normal human osteoblastic cells under a vector-averaged gravity condition.

PubMed

Nakamura, Hiroshi; Kumei, Yasuhiro; Morita, Sadao; Shimokawa, Hitoyata; Ohya, Keiichi; Shinomiya, Kenichi

2003-06-01

Spaceflight and bed rest induce loss of bone mass. A number of in vivo and in vitro studies have been conducted to clarify the mechanisms, however, the results have been conflicting. The purpose of this study was to investigate the effects of gravity unloading on proliferation, phenotypes, and apoptosis of normal human osteoblastic cells in the presence of 1alpha,25-dihydroxyvitamin D3. We used a vector-averaged gravity condition generated by clinostat rotation to simulate gravity unloading. Clinostat rotation did not affect the cell proliferation. On the first day, the mRNA levels for osteocalcin, ALP, CBFA1, VDR, RANKL, and OPG were reduced by clinostat rotation to 21%, 65%, 62%, 52%, 43%, and 54% of control, respectively. ALP activity was decreased to 75% of control. On the second day, the mRNA levels for osteocalcin and RANKL were reduced to 77% and 61% of control, respectively. The decreased VDR mRNA level might be responsible for the reduction for mRNA levels for osteocalcin, RANKL, and OPG. Clinostat rotation increased the pro-apoptotic index (Bax/Bcl-2 ratio) but did not induce apoptosis due to the simultaneous upregulation of the anti-apoptotic XIAP. Reduction of osteoblast responsiveness to 1alpha,25-dihydroxyvitamin D3 might be involved in osteopenia that is induced by gravity unloading.

IGF-1 signaling mediated cell-specific skeletal mechano-transduction.

PubMed

Tian, Faming; Wang, Yongmei; Bikle, Daniel D

2018-02-01

Mechanical loading preserves bone mass and stimulates bone formation, whereas skeletal unloading leads to bone loss. In addition to osteocytes, which are considered the primary sensor of mechanical load, osteoblasts, and bone specific mesenchymal stem cells also are involved. The skeletal response to mechanical signals is a complex process regulated by multiple signaling pathways including that of insulin-like growth factor-1 (IGF-1). Conditional osteocyte deletion of IGF-1 ablates the osteogenic response to mechanical loading. Similarly, osteocyte IGF-1 receptor (IGF-1R) expression is necessary for reloading-induced periosteal bone formation. Transgenic overexpression of IGF-1 in osteoblasts results in enhanced responsiveness to in vivo mechanical loading in mice, a response which is eliminated by osteoblastic conditional disruption of IGF-1 in vivo. Bone marrow derived stem cells (BMSC) from unloaded bone fail to respond to IGF-1 in vitro. IGF-1R is required for the transduction of a mechanical stimulus to downstream effectors, transduction which is lost when the IGF-1R is deleted. Although the molecular mechanisms are not yet fully elucidated, the IGF signaling pathway and its interactions with potentially interlinked signaling cascades involving integrins, the estrogen receptor, and wnt/β-catenin play an important role in regulating adaptive response of cancer bone cells to mechanical stimuli. In this review, we discuss recent advances investigating how IGF-1 and other interlinked molecules and signaling pathways regulate skeletal mechano-transduction involving different bone cells, providing an overview of the IGF-1 signaling mediated cell-specific response to mechanical stimuli. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:576-583, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Effects of Hypogravity on Osteoblast Differentiation

NASA Technical Reports Server (NTRS)

Globus, Ruth; Doty, Steven

1997-01-01

Weightbearing is essential for normal skeletal function. Without weightbearing, the rate of bone formation by osteoblasts decreases in the growing rat. Defective formation may account for the decrease in the maturation, strength and mass of bone that is caused by spaceflight. These skeletal defects may be mediated by a combination of physiologic changes triggered by spaceflight, including skeletal unloading, fluid shifts, and stress-induced endocrine factors. The fundamental question of whether the defects in osteoblast function due to weightlessness are mediated by localized skeletal unloading or by systemic physiologic adaptations such as fluid shifts has not been answered. Furthermore, bone-forming activity of osteoblasts during unloading may be affected by paracrine signals from vascular, monocytic, and neural cells that also reside in skeletal tissue. Therefore we proposed to examine whether exposure of cultured rat osteoblasts to spaceflight inhibits cellular differentiation and impairs mineralization when isolated from the influence of both systemic factors and other skeletal cells.

Hindlimb unloading in rat decreases preosteoblast proliferation assessed in vivo with BrdU incorporation.

PubMed

Barou, O; Palle, S; Vico, L; Alexandre, C; Lafage-Proust, M H

1998-01-01

Immobilization affects bone formation. However, the mechanisms regulating the decrease in osteoblast recruitment remain unclear. The aim of our study was to determine in vivo osteoblastic proliferation after short-term immobilization among the different bone compartments. Twelve Wistar 5-wk-old rats were assigned to two groups: six tail-suspended animals for 6 days and their six age-related controls. Osmotic minipumps, each containing 40 mg of bromodeoxyuridine (BrdU), were implanted intraperitoneally at day 4 until euthanasia. Histomorphometric measurements found a significantly lower bone volume in primary (ISP, -22%) and secondary spongiosa (IISP, -37%) in unloaded rats compared with their age-related controls. BrdU immunohistochemistry showed that the proliferation capacity of osteogenic precursors in ISP (-29%) and preosteoblasts in IISP (-80%) and in periosteum as well as bone marrow cells (-40%) was lowered by unloading. We demonstrated in vivo for the first time that 6-day tail suspension induced a significant decrease in proliferation of periosteal and trabecular preosteoblasts in ISP and IISP as well as in bone marrow cells.

Activation of GLP-1 Receptor Promotes Bone Marrow Stromal Cell Osteogenic Differentiation through β-Catenin

PubMed Central

Meng, Jingru; Ma, Xue; Wang, Ning; Jia, Min; Bi, Long; Wang, Yunying; Li, Mingkai; Zhang, Huinan; Xue, Xiaoyan; Hou, Zheng; Zhou, Ying; Yu, Zhibin; He, Gonghao; Luo, Xiaoxing

2016-01-01

Summary Glucagon-like peptide 1 (GLP-1) plays an important role in regulating bone remodeling, and GLP-1 receptor agonist shows a positive relationship with osteoblast activity. However, GLP-1 receptor is not found in osteoblast, and the mechanism of GLP-1 receptor agonist on regulating bone remodeling is unclear. Here, we show that the GLP-1 receptor agonist exendin-4 (Ex-4) promoted bone formation and increased bone mass and quality in a rat unloading-induced bone loss model. These functions were accompanied by an increase in osteoblast number and serum bone formation markers, while the adipocyte number was decreased. Furthermore, GLP-1 receptor was detected in bone marrow stromal cells (BMSCs), but not in osteoblast. Activation of GLP-1 receptor by Ex-4 promoted the osteogenic differentiation and inhibited BMSC adipogenic differentiation through regulating PKA/β-catenin and PKA/PI3K/AKT/GSK3β signaling. These findings reveal that GLP-1 receptor regulates BMSC osteogenic differentiation and provide a molecular basis for therapeutic potential of GLP-1 against osteoporosis. PMID:26947974

Estrogen receptor α in osteocytes regulates trabecular bone formation in female mice.

PubMed

Kondoh, Shino; Inoue, Kazuki; Igarashi, Katsuhide; Sugizaki, Hiroe; Shirode-Fukuda, Yuko; Inoue, Erina; Yu, Taiyong; Takeuchi, Jun K; Kanno, Jun; Bonewald, Lynda F; Imai, Yuuki

2014-03-01

Estrogens are well known steroid hormones necessary to maintain bone health. In addition, mechanical loading, in which estrogen signaling may intersect with the Wnt/β-catenin pathway, is essential for bone maintenance. As osteocytes are known as the major mechanosensory cells embedded in mineralized bone matrix, osteocyte ERα deletion mice (ERα(ΔOcy/ΔOcy)) were generated by mating ERα floxed mice with Dmp1-Cre mice to determine the role of ERα in osteocytes. Trabecular bone mineral density of female, but not male ERα(ΔOcy/ΔOcy) mice was significantly decreased. Bone formation parameters in ERα(ΔOcy/ΔOcy) were significantly decreased while osteoclast parameters were unchanged. This suggests that ERα in osteocytes exerts osteoprotective function by positively controlling bone formation. To identify potential targets of ERα, gene array analysis of Dmp1-GFP osteocytes sorted by FACS from ERα(ΔOcy/ΔOcy) and control mice was performed. Gene expression microarray followed by gene ontology analyses revealed that osteocytes from ERα(ΔOcy/ΔOcy) highly expressed genes categorized in 'Secreted' when compared to control osteocytes. Among them, expression of Mdk and Sostdc1, both of which are Wnt inhibitors, was significantly increased without alteration of expression of the mature osteocyte markers such as Sost and β-catenin. Moreover, hindlimb suspension experiments showed that trabecular bone loss due to unloading was greater in ERα(ΔOcy/ΔOcy) mice without cortical bone loss. These data suggest that ERα in osteocytes has osteoprotective functions in trabecular bone formation through regulating expression of Wnt antagonists, but conversely plays a negative role in cortical bone loss due to unloading. Published by Elsevier Inc.

The application of micro-CT in monitoring bone alterations in tail-suspended rats in vivo

NASA Astrophysics Data System (ADS)

Luan, Hui-Qin; Sun, Lian-Wen; Huang, Yun-Fei; Wang, Ying; McClean, Colin J.; Fan, Yu-Bo

2014-06-01

Osteopenia is a pathological process that affects human skeletal health not only on earth but also in long-time spaceflight. Micro-computed tomography (micro-CT) is a nondestructive method for assessing both bone quantity and bone quality. To investigate the characteristics of micro-CT on evaluating the microgravity-induced osteopenia (e.g. early detection time and the sensitive parameters), the bone loss process of tail-suspended rats was monitored by micro-CT in this study. 8-Week-old female Sprague Dawley rats were divided into two groups: tail suspension (TS) and control (CON). Volumetric bone mineral density (vBMD) and microstructure of the femur and tibia were evaluated in vivo by micro-CT at 0, 7, 14, 22 days. Biomechanical properties of the femur and tibia were determined by three-point bending test. The ash weight of bone was also investigated. The results showed that (1) bone loss in the proximal tibia appeared earlier than in the distal femur. (2) On day 7, the percent bone volume (BV/TV) of the tibia 15.44% decreased significantly, and the trabecular separation (Tb.Sp) 30.29% increased significantly in TS group, both of which were detected earlier than other parameters. (3) Biomechanical properties (e.g. femur, -22.4% maximum load and -23.75% Young’s modulus vs. CON) and ash weight of the femur and tibia decreased significantly in the TS group in comparison to CON group. (4) vBMD of the femur and tibia were clearly related to bone ash and dry weight (r = 0.75-0.87, p < 0.05). (5) BV/TV of both femur and tibia were clearly related to maximum load and Young’s modulus (r = 0.66-0.87, p < 0.05). Similarly, trabecular vBMD and BV/TV of the femur and tibia were clearly related to Young’s modulus (r = 0.73-0.89, p < 0.05). These indicated that BV/TV and Tb.Sp were more sensitive than other parameters for evaluating bone loss induced by tail suspension, moreover, trabecular vBMD and other parameters might be used to evaluate bone strength. Therefore, micro-CT is a reliable and sensitive method for predicting unloading-induced bone loss in small animals.

Predicting Bone Mechanical State During Recovery After Long-Duration Skeletal Unloading Using QCT and Finite Element Modeling

NASA Technical Reports Server (NTRS)

Chang, Katarina L.; Pennline, James A.

2013-01-01

During long-duration missions at the International Space Station, astronauts experience weightlessness leading to skeletal unloading. Unloading causes a lack of a mechanical stimulus that triggers bone cellular units to remove mass from the skeleton. A mathematical system of the cellular dynamics predicts theoretical changes to volume fractions and ash fraction in response to temporal variations in skeletal loading. No current model uses image technology to gather information about a skeletal site s initial properties to calculate bone remodeling changes and then to compare predicted bone strengths with the initial strength. The goal of this study is to use quantitative computed tomography (QCT) in conjunction with a computational model of the bone remodeling process to establish initial bone properties to predict changes in bone mechanics during bone loss and recovery with finite element (FE) modeling. Input parameters for the remodeling model include bone volume fraction and ash fraction, which are both computed from the QCT images. A non-destructive approach to measure ash fraction is also derived. Voxel-based finite element models (FEM) created from QCTs provide initial evaluation of bone strength. Bone volume fraction and ash fraction outputs from the computational model predict changes to the elastic modulus of bone via a two-parameter equation. The modulus captures the effect of bone remodeling and functions as the key to evaluate of changes in strength. Application of this time-dependent modulus to FEMs and composite beam theory enables an assessment of bone mechanics during recovery. Prediction of bone strength is not only important for astronauts, but is also pertinent to millions of patients with osteoporosis and low bone density.

Circulating sclerostin is elevated in short-term and reduced in long-term SCI.

PubMed

Battaglino, Ricardo A; Sudhakar, Supreetha; Lazzari, Antonio A; Garshick, Eric; Zafonte, Ross; Morse, Leslie R

2012-09-01

Spinal cord injury (SCI) causes profound bone loss due to muscle paralysis resulting in the inability to walk. Sclerostin, a Wnt signaling pathway antagonist produced by osteocytes, is a potent inhibitor of bone formation. Short-term studies in rodent models have demonstrated increased sclerostin in response to mechanical unloading that is reversed with reloading. Although sclerostin inhibition has been proposed as a potential therapy for bone loss, it is not known if sclerostin levels vary with duration of SCI in humans. We analyzed circulating sclerostin in 155 men with varying degrees of SCI who were 1 year or more post-injury. We report that sclerostin levels are greatest in subjects with short-term SCI (≤5 years post-injury) and decrease significantly over the first 5 years post-injury. There was no association between sclerostin and injury duration in subjects with long-term SCI (>5 years post-injury). In subjects with long-term SCI, sclerostin levels were positively associated with lower extremity bone density and bone mineral content. These data suggest that sclerostin levels are initially increased after SCI in response to mechanical unloading. This response is time-limited and as bone loss progresses, circulating sclerostin is lowest in subjects with severe osteoporosis. These findings support a dual role for sclerostin after SCI: a therapeutic target in acute SCI, and a biomarker of osteoporosis severity in chronic SCI. Copyright © 2012 Elsevier Inc. All rights reserved.

The effects of orbital spaceflight on bone histomorphometry and messenger ribonucleic acid levels for bone matrix proteins and skeletal signaling peptides in ovariectomized growing rats

NASA Technical Reports Server (NTRS)

Cavolina, J. M.; Evans, G. L.; Harris, S. A.; Zhang, M.; Westerlind, K. C.; Turner, R. T.

1997-01-01

A 14-day orbital spaceflight was performed using ovariectomized Fisher 344 rats to determine the combined effects of estrogen deficiency and near weightlessness on tibia radial bone growth and cancellous bone turnover. Twelve ovariectomized rats with established cancellous osteopenia were flown aboard the space shuttle Columbia (STS-62). Thirty ovariectomized rats were housed on earth as ground controls: 12 in animal enclosure modules, 12 in vivarium cages, and 6 killed the day of launch for baseline measurements. An additional 18 ovary-intact rats were housed in vivarium cages as ground controls: 8 rats were killed as baseline controls and the remaining 10 rats were killed 14 days later. Ovariectomy increased periosteal bone formation at the tibia-fibula synostosis; cancellous bone resorption and formation in the secondary spongiosa of the proximal tibial metaphysis; and messenger RNA (mRNA) levels for the prepro-alpha2(1) subunit of type 1 collagen, osteocalcin, transforming growth factor-beta, and insulin-like growth factor I in the contralateral proximal tibial metaphysis and for the collagen subunit in periosteum pooled from tibiae and femora and decreased cancellous bone area. Compared to ovariectomized weight-bearing rats, the flight group experienced decreases in periosteal bone formation, collagen subunit mRNA levels, and cancellous bone area. The flight rats had a small decrease in the cancellous mineral apposition rate, but no change in the calculated bone formation rate. Also, spaceflight had no effect on cancellous osteoblast and osteoclast perimeters or on mRNA levels for bone matrix proteins and signaling peptides. On the other hand, spaceflight resulted in an increase in bone resorption, as ascertained from the diminished retention of a preflight fluorochrome label. This latter finding suggests that osteoclast activity was increased. In a follow-up ground-based experiment, unilateral sciatic neurotomy of ovariectomized rats resulted in cancellous bone loss in the unloaded limb in excess of that induced by gonadal hormone deficiency. This additional bone loss was arrested by estrogen replacement. We conclude from these studies that estrogen alters the expression of signaling peptides believed to mediate skeletal adaptation to changes in mechanical usage and likewise modifies the skeletal response to mechanical unloading.

The central nervous system (CNS)-independent anti-bone-resorptive activity of muscle contraction and the underlying molecular and cellular signatures.

PubMed

Qin, Weiping; Sun, Li; Cao, Jay; Peng, Yuanzhen; Collier, Lauren; Wu, Yong; Creasey, Graham; Li, Jianhua; Qin, Yiwen; Jarvis, Jonathan; Bauman, William A; Zaidi, Mone; Cardozo, Christopher

2013-05-10

Mechanisms by which muscle regulates bone are poorly understood. Electrically stimulated muscle contraction reversed elevations in bone resorption and increased Wnt signaling in bone-derived cells after spinal cord transection. Muscle contraction reduced resorption of unloaded bone independently of the CNS, through mechanical effects and, potentially, nonmechanical signals (e.g. myokines). The study provides new insights regarding muscle-bone interactions. Muscle and bone work as a functional unit. Cellular and molecular mechanisms underlying effects of muscle activity on bone mass are largely unknown. Spinal cord injury (SCI) causes muscle paralysis and extensive sublesional bone loss and disrupts neural connections between the central nervous system (CNS) and bone. Muscle contraction elicited by electrical stimulation (ES) of nerves partially protects against SCI-related bone loss. Thus, application of ES after SCI provides an opportunity to study the effects of muscle activity on bone and roles of the CNS in this interaction, as well as the underlying mechanisms. Using a rat model of SCI, the effects on bone of ES-induced muscle contraction were characterized. The SCI-mediated increase in serum C-terminal telopeptide of type I collagen (CTX) was completely reversed by ES. In ex vivo bone marrow cell cultures, SCI increased the number of osteoclasts and their expression of mRNA for several osteoclast differentiation markers, whereas ES significantly reduced these changes; SCI decreased osteoblast numbers, but increased expression in these cells of receptor activator of NF-κB ligand (RANKL) mRNA, whereas ES increased expression of osteoprotegerin (OPG) and the OPG/RANKL ratio. A microarray analysis revealed that ES partially reversed SCI-induced alterations in expression of genes involved in signaling through Wnt, FSH, parathyroid hormone (PTH), oxytocin, and calcineurin/nuclear factor of activated T-cells (NFAT) pathways. ES mitigated SCI-mediated increases in mRNA levels for the Wnt inhibitors DKK1, sFRP2, and sclerostin in ex vivo cultured osteoblasts. Our results demonstrate an anti-bone-resorptive activity of muscle contraction by ES that develops rapidly and is independent of the CNS. The pathways involved, particularly Wnt signaling, suggest future strategies to minimize bone loss after immobilization.

The effect of purified compared with nonpurified diet on bone changes induced by hindlimb suspension of female rats

NASA Technical Reports Server (NTRS)

Tou, Janet C L.; Arnaud, Sara B.; Grindeland, Richard; Wade, Charles

2005-01-01

The purpose of this study was to compare the bone changes induced by unloading in rats fed different diets, because space flight studies use a semipurified diet, whereas space flight simulation studies typically use nonpurified diets. Female Sprague-Dawley rats were fed a purified American Institute of Nutrition (AIN) 93G diet or a standard nonpurified diet and kept ambulatory or subjected to unloading by hindlimb suspension (HLS) for 38 days. Bone mineral content (BMC), mechanical strength, and factors related to the diet that affect bone (i.e., urinary calcium excretion, estradiol, and corticosterone) were measured. Average food intakes (grams per day) differed for diets, but caloric intake (kilocalories per day) and the final body masses of treatment groups were similar. The HLS-induced decrease in femoral BMC was not statistically different for rats fed a nonpurified diet (-8.6%) compared with a purified AIN-93G diet (-11.4%). The HLS-induced decrease in femoral mechanical strength was not statistically different for rats fed a nonpurified diet (-24%) compared with a purified AIN-93G diet (-31%). However, bone lengths were decreased (P < 0.05) in rats fed a nonpurified diet compared with a purified diet. Plasma estradiol levels were lower (P < 0.05) in the HLS/AIN-93G group but similar in the HLS and ambulatory rats fed a nonpurified diet. Plasma estradiol was related to femoral BMC (r = 0.85, P < 0.01). Urinary calcium excretion was higher (P < 0.05) in rats fed a nonpurified diet than those fed a purified AIN-93G diet, which is consistent with the higher level of calcium in the nonpurified diet. Urinary corticosterone levels were higher (P < 0.05) in rats fed a nonpurified diet than rats fed the AIN-93G diet. Although the osteopenia induced by unloading was similar in both diet groups, there were differences in longitudinal bone growth, calcium excretion, plasma estradiol levels, and urinary corticosterone levels. Results indicate that the type of standard diet used is an important factor to consider when measuring bone end points.

Role of nutritional zinc in the prevention of osteoporosis.

PubMed

Yamaguchi, Masayoshi

2010-05-01

Zinc is known as an essential nutritional factor in the growth of the human and animals. Bone growth retardation is a common finding in various conditions associated with dietary zinc deficiency. Bone zinc content has been shown to decrease in aging, skeletal unloading, and postmenopausal conditions, suggesting its role in bone disorder. Zinc has been demonstrated to have a stimulatory effect on osteoblastic bone formation and mineralization; the metal directly activates aminoacyl-tRNA synthetase, a rate-limiting enzyme at translational process of protein synthesis, in the cells, and it stimulates cellular protein synthesis. Zinc has been shown to stimulate gene expression of the transcription factors runt-related transcription factor 2 (Runx2) that is related to differentiation into osteoblastic cells. Moreover, zinc has been shown to inhibit osteoclastic bone resorption due to inhibiting osteoclast-like cell formation from bone marrow cells and stimulating apoptotic cell death of mature osteoclasts. Zinc has a suppressive effect on the receptor activator of nuclear factor (NF)-kappaB ligand (RANKL)-induced osteoclastogenesis. Zinc transporter has been shown to express in osteoblastic and osteoclastic cells. Zinc protein is involved in transcription. The intake of dietary zinc causes an increase in bone mass. beta-Alanyl-L: -histidinato zinc (AHZ) is a zinc compound, in which zinc is chelated to beta-alanyl-L: -histidine. The stimulatory effect of AHZ on bone formation is more intensive than that of zinc sulfate. Zinc acexamate has also been shown to have a potent-anabolic effect on bone. The oral administration of AHZ or zinc acexamate has the restorative effect on bone loss under various pathophysiologic conditions including aging, skeletal unloading, aluminum bone toxicity, calcium- and vitamin D-deficiency, adjuvant arthritis, estrogen deficiency, diabetes, and fracture healing. Zinc compounds may be designed as new supplementation factor in the prevention and therapy of osteoporosis.

Sclerostin antibody inhibits skeletal deterioration in mice exposed to partial weight-bearing

NASA Astrophysics Data System (ADS)

Spatz, J. M.; Ellman, R.; Cloutier, A. M.; Louis, L.; van Vliet, M.; Dwyer, D.; Stolina, M.; Ke, H. Z.; Bouxsein, M. L.

2017-02-01

Whereas much is known regarding the musculoskeletal responses to full unloading, little is known about the physiological effects and response to pharmacological agents in partial unloading (e.g. Moon and Mars) environments. To address this, we used a previously developed ground-based model of partial weight-bearing (PWB) that allows chronic exposure to reduced weight-bearing in mice to determine the effects of murine sclerostin antibody (SclAbII) on bone microstructure and strength across different levels of mechanical unloading. We hypothesize that treatment with SclAbII would improve bone mass, microarchitecture and strength in all loading conditions, but that there would be a greater skeletal response in the normally loaded mice than in partially unloaded mice suggesting the importance of combined countermeasures for exploration-class long duration spaceflight missions. Eleven-week-old female mice were assigned to one of four loading groups: normal weight-bearing controls (CON) or weight-bearing at 20% (PWB20), 40% (PWB40) or 70% (PWB70) of normal. Mice in each group received either SclAbII (25 mg/kg) or vehicle (VEH) via twice weekly subcutaneous injection for 3 weeks. In partially-unloaded VEH-treated groups, leg BMD decreased -5 to -10% in a load-dependent manner. SclAbII treatment completely inhibited bone deterioration due to PWB, with bone properties in SclAbII-treated groups being equal to or greater than those of CON, VEH-treated mice. SclAbII treatment increased leg BMD from +14 to +18% in the PWB groups and 30 ± 3% in CON (p < 0.0001 for all). Trabecular bone volume, assessed by μCT at the distal femur, was lower in all partially unloaded VEH-treated groups vs. CON-VEH (p < 0.05), and was 2-3 fold higher in SclAbII-treated groups (p < 0.001). Midshaft femoral strength was also significantly higher in SclAbII vs. VEH-groups in all-loading conditions. These results suggest that greater weight bearing leads to greater benefits of SclAbII on bone mass, particularly in the trabecular compartment. Altogether, these results demonstrate the efficacy of sclerostin antibody therapy in preventing astronaut bone loss during terrestrial solar system exploration.

Sclerostin antibody inhibits skeletal deterioration in mice exposed to partial weight-bearing.

PubMed

Spatz, J M; Ellman, R; Cloutier, A M; Louis, L; van Vliet, M; Dwyer, D; Stolina, M; Ke, H Z; Bouxsein, M L

2017-02-01

Whereas much is known regarding the musculoskeletal responses to full unloading, little is known about the physiological effects and response to pharmacological agents in partial unloading (e.g. Moon and Mars) environments. To address this, we used a previously developed ground-based model of partial weight-bearing (PWB) that allows chronic exposure to reduced weight-bearing in mice to determine the effects of murine sclerostin antibody (SclAbII) on bone microstructure and strength across different levels of mechanical unloading. We hypothesize that treatment with SclAbII would improve bone mass, microarchitecture and strength in all loading conditions, but that there would be a greater skeletal response in the normally loaded mice than in partially unloaded mice suggesting the importance of combined countermeasures for exploration-class long duration spaceflight missions. Eleven-week-old female mice were assigned to one of four loading groups: normal weight-bearing controls (CON) or weight-bearing at 20% (PWB20), 40% (PWB40) or 70% (PWB70) of normal. Mice in each group received either SclAbII (25mg/kg) or vehicle (VEH) via twice weekly subcutaneous injection for 3 weeks. In partially-unloaded VEH-treated groups, leg BMD decreased -5 to -10% in a load-dependent manner. SclAbII treatment completely inhibited bone deterioration due to PWB, with bone properties in SclAbII-treated groups being equal to or greater than those of CON, VEH-treated mice. SclAbII treatment increased leg BMD from +14 to +18% in the PWB groups and 30 ± 3% in CON (p< 0.0001 for all). Trabecular bone volume, assessed by μCT at the distal femur, was lower in all partially unloaded VEH-treated groups vs. CON-VEH (p< 0.05), and was 2-3 fold higher in SclAbII-treated groups (p< 0.001). Midshaft femoral strength was also significantly higher in SclAbII vs. VEH-groups in all-loading conditions. These results suggest that greater weight bearing leads to greater benefits of SclAbII on bone mass, particularly in the trabecular compartment. Altogether, these results demonstrate the efficacy of sclerostin antibody therapy in preventing astronaut bone loss during terrestrial solar system exploration. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Hindlimb unloading of growing rats: a model for predicting skeletal changes during space flight.

PubMed

Morey-Holton, E R; Globus, R K

1998-05-01

A model that uses hindlimb unloading of rats was developed to study the consequences of skeletal unloading and reloading as occurs during and following space flight. Studies using the model were initiated two decades ago and further developed at National Aeronautics and Space Administration (NASA)-Ames Research Center. The model mimics some aspects of exposure to microgravity by removing weightbearing loads from the hindquarters and producing a cephalic fluid shift. Unlike space flight, the forelimbs remain loaded in the model, providing a useful internal control to distinguish between the local and systemic effects of hindlimb unloading. Rats that are hindlimb unloaded by tail traction gain weight at the same rate as pairfed controls, and glucocorticoid levels are not different from controls, suggesting that systemic stress is minimal. Unloaded bones display reductions in cancellous osteoblast number, cancellous mineral apposition rate, trabecular bone volume, cortical periosteal mineralization rate, total bone mass, calcium content, and maturation of bone mineral relative to controls. Subsequent studies reveal that these changes also occur in rats exposed to space flight. In hindlimb unloaded rats, bone formation rates and masses of unloaded bones decline relative to controls, while loaded bones do not change despite a transient reduction in serum 1,25-dihydroxyvitamin D (1,25D) concentrations. Studies using the model to evaluate potential countermeasures show that 1,25D, growth hormone, dietary calcium, alendronate, and muscle stimulation modify, but do not completely correct, the suppression of bone growth caused by unloading, whereas continuous infusion of transforming growth factor-beta2 or insulin-like growth factor-1 appears to protect against some of the bone changes caused by unloading. These results emphasize the importance of local as opposed to systemic factors in the skeletal response to unloading, and reveal the pivotal role that osteoblasts play in the response to gravitational loading. The hindlimb unloading model provides a unique opportunity to evaluate in detail the physiological and cellular mechanisms of the skeletal response to weightbearing loads, and has proven to be an effective model for space flight.

Hindlimb unloading of growing rats: a model for predicting skeletal changes during space flight

NASA Technical Reports Server (NTRS)

Morey-Holton, E. R.; Globus, R. K.

1998-01-01

A model that uses hindlimb unloading of rats was developed to study the consequences of skeletal unloading and reloading as occurs during and following space flight. Studies using the model were initiated two decades ago and further developed at National Aeronautics and Space Administration (NASA)-Ames Research Center. The model mimics some aspects of exposure to microgravity by removing weightbearing loads from the hindquarters and producing a cephalic fluid shift. Unlike space flight, the forelimbs remain loaded in the model, providing a useful internal control to distinguish between the local and systemic effects of hindlimb unloading. Rats that are hindlimb unloaded by tail traction gain weight at the same rate as pairfed controls, and glucocorticoid levels are not different from controls, suggesting that systemic stress is minimal. Unloaded bones display reductions in cancellous osteoblast number, cancellous mineral apposition rate, trabecular bone volume, cortical periosteal mineralization rate, total bone mass, calcium content, and maturation of bone mineral relative to controls. Subsequent studies reveal that these changes also occur in rats exposed to space flight. In hindlimb unloaded rats, bone formation rates and masses of unloaded bones decline relative to controls, while loaded bones do not change despite a transient reduction in serum 1,25-dihydroxyvitamin D (1,25D) concentrations. Studies using the model to evaluate potential countermeasures show that 1,25D, growth hormone, dietary calcium, alendronate, and muscle stimulation modify, but do not completely correct, the suppression of bone growth caused by unloading, whereas continuous infusion of transforming growth factor-beta2 or insulin-like growth factor-1 appears to protect against some of the bone changes caused by unloading. These results emphasize the importance of local as opposed to systemic factors in the skeletal response to unloading, and reveal the pivotal role that osteoblasts play in the response to gravitational loading. The hindlimb unloading model provides a unique opportunity to evaluate in detail the physiological and cellular mechanisms of the skeletal response to weightbearing loads, and has proven to be an effective model for space flight.

Does Simulated Spaceflight Modify Epigenetic Status During Bone Remodeling?

NASA Technical Reports Server (NTRS)

Thomas, Nicholas J.; Stevick, Rebecca J.; Tran, Luan H.; Nalavadi, Mohit O.; Almeida, Eduardo A.C.; Globus, Ruth K.; Alwood, Joshua S.

2015-01-01

Little is known about the effects of spaceflight conditions on epigenetics. The term epigenetics describes changes to the genome that can affect expression of a gene without changes to the sequence of DNA. Epigenetic processes are thought to underlie cellular differentiation, where transcription of specific genes occurs in response to key stimuli, and may be heritable - passing from one cell to its daughter cell. We hypothesize that the mechanical environment during spaceflight, namely microgravity-induced weightlessness or exercise regulate gene expression in the osteoblast-lineage cells both to control bone formation by osteoblasts and bone resorption by osteoclasts, which continually shapes bone structure throughout life. Similarly we intend to evaluate how radiation regulates these same bone cell activity and differentiation related genes. We further hypothesize that the regulation in bone cell gene expression is at least partially controlled through epigenetic mechanisms of methylation or small non-coding RNA (microRNAs). We have acquired preliminary data suggesting that global genome methylation is modified in response to axial compression of the tibia - a model of exercise. We intend to pursue these hypotheses wherein we will evaluate changes in gene expression and, congruently, changes in epigenetic state in bones from mice subjected to the aforementioned conditions: hindlimb unloading to simulate weightlessness, axial compression of the tibia, or radiation exposure in order to gain insight into the role of epigenetics in spaceflight-induced bone loss.

Interleukin-2 therapy reverses some immunosuppressive effects of skeletal unloading

NASA Technical Reports Server (NTRS)

Armstrong, Jason W.; Balch, Signe; Chapes, Stephen K.

1994-01-01

Using antiorthostatic suspension, we characterized hematopoietic changes that may be responsible for the detrimental effect of skeletal unloading on macrophage development. Skeletally unloaded mice had suppressed macrophage development in unloaded and loaded bones, which indicated a systemic effect. Bone marrow cells from unloaded mice secreted less macrophage colony-stimulating factor and interleukin-6 than control mice. Additionally, T-lymphocyte proliferation was reduced after skeletal unloading. We show that polyethylene glycol-interleukin-2 therapy reversed the effects of skeletal unloading on macrophage development and cell proliferation.

The molecular response of bone to growth hormone during skeletal unloading: regional differences

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Harris, J.; Halloran, B. P.; Currier, P. A.; Tanner, S.; Morey-Holton, E.

1995-01-01

Hind limb elevation of the growing rat provides a good model for the skeletal changes that occur during space flight. In this model the bones of the forelimbs (normally loaded) are used as an internal control for the changes that occur in the unloaded bones of the hind limbs. Previous studies have shown that skeletal unloading of the hind limbs results in a transient reduction of bone formation in the tibia and femur, with no change in the humerus. This fall in bone formation is accompanied by a fall in serum osteocalcin (bone Gla protein, BGP) and bone BGP messenger RNA (mRNA) levels, but a rise in bone insulin-like growth factor-I (IGF-I) protein and mRNA levels and resistance to the skeletal growth-promoting actions of IGF-I. To determine whether skeletal unloading also induced resistance to GH, we evaluated the response of the femur and humerus of sham and hypophysectomized rats, control and hind limb elevated, to GH (two doses), measuring mRNA levels of IGF-I, BGP, rat bone alkaline phosphatase (RAP), and alpha 1(1)-procollagen (coll). Hypophysectomy (HPX) decreased the mRNA levels of IGF-I, BGP, and coll in the femur, but was either less effective or had the opposite effect in the humerus. GH at the higher dose (500 micrograms/day) restored these mRNA levels to or above the sham control values in the femur, but generally had little or no effect on the humerus. RAP mRNA levels were increased by HPX, especially in the femur. The lower dose of GH (50 micrograms/day) inhibited this rise in RAP, whereas the higher dose raised the mRNA levels and resulted in the appearance of additional transcripts not seen in controls. As for the other mRNAs, RAP mRNA in the humerus was less affected by HPX or GH than that in the femur. Hind limb elevation led to an increase in IGF-I, coll, and RAP mRNAs and a reduction in BGP mRNA in the femur and either had no effect or potentiated the response of these mRNAs to GH. We conclude that GH stimulates a number of markers of bone formation by raising their mRNA levels, and that skeletal unloading does not block this response, but the response varies substantially from bone to bone.

Skeletal Responses to Long-Duration Simulated Weightlessness in Rats

NASA Technical Reports Server (NTRS)

Adams, Julia; Torres, Samantha; Schreurs, Ann-Sofie; Alwood, Joshua S.; Shirazi-Fard, Yasaman; Tahimic, Candice; Globus, Ruth

2017-01-01

Damaging effects due to spaceflight and long-duration weightlessness are seen in the musculoskeletal system, specifically with regards to bone loss, bone resorption, and changes in overall bone structure. These adverse effects are all seen with indicators of oxidative stress and a variation in the levels of oxidative gene expression. Once gravity is restored, however, the recovery is slow and incomplete. Despite this, few reports have investigated the correlation between oxidative damage and general modifications within the bone. In this project, we will make use of a ground-based model of simulated weightlessness (hindlimb unloading, HU) in order to observe skeletal changes in response to induced microgravity due to changes in oxidative pressures. With this model we will analyze samples at 14-day and 90-day time points following HU for the determination of acute and chronic effects, each with corresponding controls. We hypothesize that simulated microgravity will lead to skeletal adaptations including time-dependent activation of pro-oxidative processes and pro-osteoclastogenic signals related to the progression, plateau, and recovery of the bone. Microcomputed tomography techniques will be utilized to measure skeletal changes in response to HU. With the results of this study, we hope to further the understanding of skeletal affects as a result of long-duration weightlessness and develop countermeasures to combat bone loss in spaceflight and osteoporosis on Earth.

Directed Research in Bone Discipline: Refining Previous Research Observations for Space Medicine

NASA Technical Reports Server (NTRS)

Sibonga, Jean D.

2015-01-01

Dual-energy X-ray absorptiometry bone mass density, as a sole index, is an insufficient surrogate for fracture; Clinical Practice Guidelines using bone mass density (both World Health Organization and FRAX) are not specific for complicated subjects such as young, healthy persons following prolonged exposure to skeletal unloading (i.e. an attribute of spaceflight); Research data suggest that spaceflight induces changes to astronaut bones that could be profound, possibly irreversible and unlike age-related bone loss on Earth.; There is a need to objectively assess factors across human physiology that are also influenced by spaceflight (e.g., muscle) that contribute to fracture risk. Some of these objective assessments may require innovative technologies, analyses and modeling.; Astronauts are also exposed to novel situations that may overload their bones highlighting a need integrate biomechanics of physical activities into risk assessments.; As we accumulate data, which reflects the biomechanical competence of bone under specific mechanically-loaded scenarios (even activities of daily living), BONE expects Bone Fracture Module to be more sensitive and/or have less uncertainty in its assessments of fracture probability.; Fracture probability drives the requirement for countermeasures. Level of evidence will unlikely be obtained; hence, the Bone Research and Clinical Advisory Panel (like a Data Safety Monitoring Board) will provide the recommendations.

Bone mechanobiology, gravity and tissue engineering: effects and insights.

PubMed

Ruggiu, Alessandra; Cancedda, Ranieri

2015-12-01

Bone homeostasis strongly depends on fine tuned mechanosensitive regulation signals from environmental forces into biochemical responses. Similar to the ageing process, during spaceflights an altered mechanotransduction occurs as a result of the effects of bone unloading, eventually leading to loss of functional tissue. Although spaceflights represent the best environment to investigate near-zero gravity effects, there are major limitations for setting up experimental analysis. A more feasible approach to analyse the effects of reduced mechanostimulation on the bone is represented by the 'simulated microgravity' experiments based on: (1) in vitro studies, involving cell cultures studies and the use of bioreactors with tissue engineering approaches; (2) in vivo studies, based on animal models; and (3) direct analysis on human beings, as in the case of the bed rest tests. At present, advanced tissue engineering methods allow investigators to recreate bone microenvironment in vitro for mechanobiology studies. This group and others have generated tissue 'organoids' to mimic in vitro the in vivo bone environment and to study the alteration cells can go through when subjected to unloading. Understanding the molecular mechanisms underlying the bone tissue response to mechanostimuli will help developing new strategies to prevent loss of tissue caused by altered mechanotransduction, as well as identifying new approaches for the treatment of diseases via drug testing. This review focuses on the effects of reduced gravity on bone mechanobiology by providing the up-to-date and state of the art on the available data by drawing a parallel with the suitable tissue engineering systems. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of microgravity on bone and calcium homeostasis

NASA Astrophysics Data System (ADS)

Zérath, E.

Mechanical function is known to be of crucial importance for the maintenance of bone tissue. Gravity on one hand and muscular effort on the other hand are required for normal skeletal structure. It has been shown by numerous experimental studies that loss of total-body calcium, and marked skeletal changes occur in people who have flown in space. However, most of the pertinent investigations have been conducted on animal models, including rats and non-human primates, and a reasonably clear picture of bone response to spaceflight has emerged during the past few years. Osteopenia induced by microgravity was found to be associated with reduction in both cortical and trabecular bone formation, alteration in mineralization patterns, and disorganization of collagen, and non-collagenous protein metabolism. Recently, cell-culture techniques have offered a direct approach of altered gravity effects at the osteoblastic-cell level. But the fundamental mechanisms by which bone and calcium are lost during spaceflight are not yet fully known. Infrequenccy and high financial cost of flights have created the necessity to develop on-Earth models designed to mimic weightlessness effects. Antiorthostatic suspension devices are now commonly used to obtain hindlimb unloading in rats, with skeletal effects similar to those observed after spaceflight. Therefore, actual and ``simulated'' spaceflights, with investigations conducted at whole body and cellular levels, are needed to elucidate pathogeny of bone loss in space, to develop effective countermeasures, and to study recovery processes of bone changes after return to Earth.

Stimulating angiogenesis mitigates the unloading-induced reduction in osteogenesis in early-stage bone repair in rats

PubMed Central

Matsumoto, Takeshi; Sato, Shota

2015-01-01

Accelerating fracture healing during bed rest allows early mobilization and avoids prolonged fracture healing times. We tested the hypothesis that stimulating angiogenesis with deferoxamine (DFO) mitigates the unloading-induced reduction in early-stage bone repair. Rats aged 12 weeks were subjected to cortical drilling on their tibial diaphysis under anesthesia and treated with hindlimb unloading (HU), HU and DFO administration (DFOHU), or weight bearing (WB) for 5 or 10 days (HU5/10, DFOHU5/10, WB5/10; n = 8 per groups) until sacrifice for vascular casting with a zirconium dioxide-based contrast agent. Taking advantage of its absorption discontinuity at the K-absorption edge, vascular and bone images in the drill-hole defects were acquired by synchrotron radiation subtraction CT. Bone repair was reduced in HU rats. The bone volume fraction (B.Vf) was 88% smaller in HU5 and 42% smaller in HU10 than in WB5/10. The bone segment densities (B.Seg) were 97% smaller in HU5 and 141% larger in HU10 than in WB5/10, and bone thickness (B.Th) was 38% smaller in HU10 than in WB10. The vascular volume fraction (V.Vf) was 35% and the mean vessel diameter (V.D) was 13% smaller in HU10 than in WB10. When compared according to categorized vessel sizes, V.Vf in the diameter ranges 20–30, 30–40, and >40 μm were smaller in HU10 than in WB10, and V.Seg in the diameter range >40 μm was smaller in HU10 than in WB10. In contrast, there was no difference in B.Vf between DFOHU5/10 and WB5/10 and in V.Vf between DFOHU10 and WB10, though B.Seg remained 86% smaller in DFOHU5 and 94% larger in DFOHU10 than in WB5/10, and B.Th and V.D were 23% and 14% lower in DFOHU10 than in WB10. Vessel size-specific V.Vf in the diameter ranges 10–20 and 20–30 μm was larger in DFOHU5 than in HU5. In conclusion, the enhanced angiogenic ingrowth mitigates the reduction in bone repair during mechanical unloading. PMID:25780087

The Role of Nutrition in the Changes in Bone and Calcium Metabolism During Space Flight

NASA Technical Reports Server (NTRS)

Morey-Holton, Emily R.; Arnaud, Sara B.

1995-01-01

On Earth, the primary purpose of the skeleton is provide structural support for the body. In space, the support function of the skeleton is reduced since, without gravity, structures have only mass and no weight. The adaptation to space flight is manifested by shifts in mineral distribution, altered bone turnover, and regional mineral deficits in weight-bearing bones. The shifts in mineral distribution appear to be related to the cephalic fluid shift. The redistribution of mineral from one bone to another or to and from areas in the same bone in response to alterations in gravitational loads is more likely to affect skeletal function than quantitative whole body losses and gains. The changes in bone turnover appear dependent upon changes in body weight with weight loss tending to increase bone resorption as well as decrease bone formation. During bedrest, the bone response to unloading varies depending upon the routine activity level of the subjects with more active subjects showing a greater suppression of bone formation in the iliac crest with inactivity. Changes in body composition during space flight are predicted by bedrest studies on Earth which show loss of lean body mass and increase tn body fat in adult males after one month. In ambulatory studies on Earth, exercising adult males of the same age, height, g weight, body mass index, and shoe size show significantly higher whole body mineral and lean body mass. than non-exercising subjects. Nutritional preference appears to change with activity level. Diet histories in exercisers and nonexercisers who maintain identical body weights show no differences in nutrients except for slightly higher carbohydrate intake in the exercisers. The absence of differences in dietary calcium in men with higher total body calcium is noteworthy. In this situation, the increased bone mineral content was facilitated by the calcium endocrine system. This regulatory system can be by-passed by raising dietary calcium. Increased calcium intake can increase the calcium content in normally loaded bone. However, bone with a higher calcium content still decreases proportionally to normal bone during unloading. Nutritional requirements in space should be reevaluated with respect to these adaptive changes to loading and physical activity.

Muscle Atrophy Induced by Mechanical Unloading: Mechanisms and Potential Countermeasures

PubMed Central

Gao, Yunfang; Arfat, Yasir; Wang, Huiping; Goswami, Nandu

2018-01-01

Prolonged periods of skeletal muscle inactivity or mechanical unloading (bed rest, hindlimb unloading, immobilization, spaceflight and reduced step) can result in a significant loss of musculoskeletal mass, size and strength which ultimately lead to muscle atrophy. With advancement in understanding of the molecular and cellular mechanisms involved in disuse skeletal muscle atrophy, several different signaling pathways have been studied to understand their regulatory role in this process. However, substantial gaps exist in our understanding of the regulatory mechanisms involved, as well as their functional significance. This review aims to update the current state of knowledge and the underlying cellular mechanisms related to skeletal muscle loss during a variety of unloading conditions, both in humans and animals. Recent advancements in understanding of cellular and molecular mechanisms, including IGF1-Akt-mTOR, MuRF1/MAFbx, FOXO, and potential triggers of disuse atrophy, such as calcium overload and ROS overproduction, as well as their role in skeletal muscle protein adaptation to disuse is emphasized. We have also elaborated potential therapeutic countermeasures that have shown promising results in preventing and restoring disuse-induced muscle loss. Finally, identified are the key challenges in this field as well as some future prospectives. PMID:29615929

Perspective on the impact of weightlessness on calcium and bone metabolism

NASA Technical Reports Server (NTRS)

Holick, M. F.

1998-01-01

As humans venture into space to colonize the moon and travel to distant planets in the 21st century, they will be confronted with a bone disease that could potentially limit their space exploration activities or put them at risk for fracture when they return to earth. It is now recognized that an unloading of the skeleton, either due to strict bed rest or in zero gravity, leads on average to a 1%-2% reduction in bone mineral density at selected skeletal sites each month. The mechanism by which unloading of the skeleton results in rapid mobilization of calcium stores from the skeleton is not fully understood, but it is thought to be related to down regulation in PTH and 1,25-dihydroxyvitamin D3 production. Bone modeling and mineralization in chick embryos is not affected by microgravity, suggesting that bone cells adapt and ultimately become addicted to gravity in order to maintain a structurally sound skeleton. Strategies need to be developed to decrease microgravity-induced bone resorption by either mimicking gravity's effect on bone metabolism, or enhancing physically or pharmacologically bone formation in order to preserve astronauts' bone health.

Perspective on the impact of weightlessness on calcium and bone metabolism.

PubMed

Holick, M F

1998-05-01

As humans venture into space to colonize the moon and travel to distant planets in the 21st century, they will be confronted with a bone disease that could potentially limit their space exploration activities or put them at risk for fracture when they return to earth. It is now recognized that an unloading of the skeleton, either due to strict bed rest or in zero gravity, leads on average to a 1%-2% reduction in bone mineral density at selected skeletal sites each month. The mechanism by which unloading of the skeleton results in rapid mobilization of calcium stores from the skeleton is not fully understood, but it is thought to be related to down regulation in PTH and 1,25-dihydroxyvitamin D3 production. Bone modeling and mineralization in chick embryos is not affected by microgravity, suggesting that bone cells adapt and ultimately become addicted to gravity in order to maintain a structurally sound skeleton. Strategies need to be developed to decrease microgravity-induced bone resorption by either mimicking gravity's effect on bone metabolism, or enhancing physically or pharmacologically bone formation in order to preserve astronauts' bone health.

The temporal response of bone to unloading

NASA Technical Reports Server (NTRS)

Globus, R. K.; Bikle, D. D.; Morey-Holton, E.

1984-01-01

Rats were suspended by their tails with the forelimbs bearing the weight load to simulate the weightlessness of space flight. Growth in bone mass ceased by 1 week in the hindlimbs and lumbar vertebrae in growing rats, while growth in the forelimbs and cervical vertebrae remained unaffected. The effects of selective skeletal unloading on bone formation during 2 weeks of suspension was investigated using radio iostope incorporation (with Ca-45 and H-3 proline) and histomorphometry (with tetracycline labeling). The results of these studies were confirmed by histomorphometric measurements of bone formation using triple tetracycline labeling. This model of simulated weightlessness results in an initial inhibition of bone formation in the unloaded bones. This temporary cessation of bone formation is followed in the accretion of bone mass, which then resumes at a normal rate by 14 days, despite continued skeletal unloading. This cycle of inhibition and resumption of bone formation has profound implication for understanding bone dynamics durng space flight, immobilization, or bed rest and offers an opportunity to study the hormonal and mechanical factors that regulate bone formation.

A "Bony" Proposition: Pathways Mediating Responses to Simulated Weightlessness and Radiation

NASA Technical Reports Server (NTRS)

Tahimic, Candice; Globus, Ruth

2016-01-01

There is evidence that weightlessness and radiation, two elements of the spaceflight environment, can lead to detrimental changes in human musculoskeletal tissue, including bone loss and muscle atrophy. This bone loss is thought to be brought about by the increased activity of bone-resorbing osteoclasts and functional changes in bone-forming osteoblasts, cells that give rise to mature osteocytes. My current area of research focuses on understanding the mechanistic basis for the responses of bone to the spaceflight environment using earth-based animal and cellular models. The overarching goal is to identify molecular targets to prevent bone loss in space exploration and earth-based scenarios of radiotherapy, accidental radiation exposure and reduced mobility. In this talk, I will highlight two signaling pathways that potentially play a role in the response of bone to spaceflight-like conditions. Firstly, I will discuss the role of insulin-like growth factor 1 (IGF1) signaling as it pertains to the recovery of bone from simulated weightlessness (rodent hindlimb unloading model). Secondly, I will share recent findings from our study that aims to understand the emerging role of autophagy in maintaining the balance between bone formation and resorption (bone homeostasis) as well as normal skeletal structure.

Resistance exercise as a countermeasure to disuse-induced bone loss.

PubMed

Shackelford, L C; LeBlanc, A D; Driscoll, T B; Evans, H J; Rianon, N J; Smith, S M; Spector, E; Feeback, D L; Lai, D

2004-07-01

During spaceflight, skeletal unloading results in loss of bone mineral density (BMD). This occurs primarily in the spine and lower body regions. This loss of skeletal mass could prove hazardous to astronauts on flights of long duration. In this study, intense resistance exercise was used to test whether a training regimen would prevent the loss of BMD that accompanies disuse. Nine subjects (5 men, 4 women) participated in a supine maximal resistance exercise training program during 17 wk of horizontal bed rest. These subjects were compared with 18 control subjects (13 men, 5 women) who followed the same bed rest protocol without exercise. Determination of treatment effect was based on measures of BMD, bone metabolism markers, and calcium balance obtained before, during, and after bed rest. Exercisers and controls had significantly (P < 0.05) different means, represented by the respective following percent changes: lumbar spine BMD, +3% vs. -1%; total hip BMD, +1% vs. -3%; calcaneus BMD, +1% vs. -9%; pelvis BMD, -0.5% vs. -3%; total body BMD, 0% vs. -1%; bone-specific alkaline phosphatase, +64% vs. 0%; alkaline phosphatase, +31% vs. +5%; osteocalcin, +43% vs. +10%; 1,25 dihydroxyvitamin D, +12% vs. -15%; parathyroid hormone intact molecule, +18% vs. -25%; and serum and ionized calcium, -1% vs. +1%. The difference in net calcium balance was also significant (+21 mg/day vs. -199 mg/day, exercise vs. control). The gastrocnemius and soleus muscle volumes decreased significantly in the exercise group, but the loss was significantly less than observed in the control group. The results indicate that resistance exercise had a positive treatment effect and thus might be useful as a countermeasure to prevent the deleterious skeletal changes associated with long-duration spaceflight.

Resistance exercise as a countermeasure to disuse-induced bone loss

NASA Technical Reports Server (NTRS)

Shackelford, L. C.; LeBlanc, A. D.; Driscoll, T. B.; Evans, H. J.; Rianon, N. J.; Smith, S. M.; Spector, E.; Feeback, D. L.; Lai, D.

2004-01-01

During spaceflight, skeletal unloading results in loss of bone mineral density (BMD). This occurs primarily in the spine and lower body regions. This loss of skeletal mass could prove hazardous to astronauts on flights of long duration. In this study, intense resistance exercise was used to test whether a training regimen would prevent the loss of BMD that accompanies disuse. Nine subjects (5 men, 4 women) participated in a supine maximal resistance exercise training program during 17 wk of horizontal bed rest. These subjects were compared with 18 control subjects (13 men, 5 women) who followed the same bed rest protocol without exercise. Determination of treatment effect was based on measures of BMD, bone metabolism markers, and calcium balance obtained before, during, and after bed rest. Exercisers and controls had significantly (P < 0.05) different means, represented by the respective following percent changes: lumbar spine BMD, +3% vs. -1%; total hip BMD, +1% vs. -3%; calcaneus BMD, +1% vs. -9%; pelvis BMD, -0.5% vs. -3%; total body BMD, 0% vs. -1%; bone-specific alkaline phosphatase, +64% vs. 0%; alkaline phosphatase, +31% vs. +5%; osteocalcin, +43% vs. +10%; 1,25 dihydroxyvitamin D, +12% vs. -15%; parathyroid hormone intact molecule, +18% vs. -25%; and serum and ionized calcium, -1% vs. +1%. The difference in net calcium balance was also significant (+21 mg/day vs. -199 mg/day, exercise vs. control). The gastrocnemius and soleus muscle volumes decreased significantly in the exercise group, but the loss was significantly less than observed in the control group. The results indicate that resistance exercise had a positive treatment effect and thus might be useful as a countermeasure to prevent the deleterious skeletal changes associated with long-duration spaceflight.

Responds of Bone Cells to Microgravity: Ground-Based Research

NASA Astrophysics Data System (ADS)

Zhang, Jian; Li, Jingbao; Xu, Huiyun; Yang, Pengfei; Xie, Li; Qian, Airong; Zhao, Yong; Shang, Peng

2015-11-01

Severe loss of bone occurs due to long-duration spaceflight. Mechanical loading stimulates bone formation, while bone degradation happens under mechanical unloading. Bone remodeling is a dynamic process in which bone formation and bone resorption are tightly coupled. Increased bone resorption and decreased bone formation caused by reduced mechanical loading, generally result in disrupted bone remodeling. Bone remodeling is orchestrated by multiple bone cells including osteoblast, osteocyte, osteoclast and mesenchymal stem cell. It is yet not clear that how these bone cells sense altered gravity, translate physical stimulus into biochemical signals, and then regulate themselves structurally and functionally. In this paper, studies elucidating the bioeffects of microgravity on bone cells (osteoblast, osteocyte, osteoclast, mesenchymal stem cell) using various platforms including spaceflight and ground-based simulated microgravity were summarized. Promising gravity-sensitive signaling pathways and protein molecules were proposed.

Low dose PTH improves metaphyseal bone healing more when muscles are paralyzed.

PubMed

Sandberg, Olof; Macias, Brandon R; Aspenberg, Per

2014-06-01

Stimulation of bone formation by PTH is related to mechanosensitivity. The response to PTH treatment in intact bone could therefore be blunted by unloading. We studied the effects of mechanical loading on the response to PTH treatment in bone healing. Most fractures occur in the metaphyses, therefor we used a model for metaphyseal bone injury. One hind leg of 20 male SD rats was unloaded via intramuscular botulinum toxin injections. Two weeks later, the proximal unloaded tibia had lost 78% of its trabecular contents. At this time-point, the rats received bilateral proximal tibiae screw implants. Ten of the 20 rats were given daily injections of 5 μg/kg PTH (1-34). After two weeks of healing, screw fixation was measured by pull-out, and microCT of the distal femur cancellous compartment was performed. Pull-out force provided an estimate for cancellous bone formation after trauma. PTH more than doubled the pull-out force in the unloaded limbs (from 14 to 30 N), but increased it by less than half in the loaded ones (from 30 to 44 N). In relative terms, PTH had a stronger effect on pull-out force in unloaded bone than in loaded bone (p=0.03). The results suggest that PTH treatment for stimulation of bone healing does not require simultaneous mechanical stimulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Stimulating angiogenesis mitigates the unloading-induced reduction in osteogenesis in early-stage bone repair in rats.

PubMed

Matsumoto, Takeshi; Sato, Shota

2015-03-01

Accelerating fracture healing during bed rest allows early mobilization and avoids prolonged fracture healing times. We tested the hypothesis that stimulating angiogenesis with deferoxamine (DFO) mitigates the unloading-induced reduction in early-stage bone repair. Rats aged 12 weeks were subjected to cortical drilling on their tibial diaphysis under anesthesia and treated with hindlimb unloading (HU), HU and DFO administration (DFOHU), or weight bearing (WB) for 5 or 10 days (HU5/10, DFOHU5/10, WB5/10; n = 8 per groups) until sacrifice for vascular casting with a zirconium dioxide-based contrast agent. Taking advantage of its absorption discontinuity at the K-absorption edge, vascular and bone images in the drill-hole defects were acquired by synchrotron radiation subtraction CT. Bone repair was reduced in HU rats. The bone volume fraction (B.Vf) was 88% smaller in HU5 and 42% smaller in HU10 than in WB5/10. The bone segment densities (B.Seg) were 97% smaller in HU5 and 141% larger in HU10 than in WB5/10, and bone thickness (B.Th) was 38% smaller in HU10 than in WB10. The vascular volume fraction (V.Vf) was 35% and the mean vessel diameter (V.D) was 13% smaller in HU10 than in WB10. When compared according to categorized vessel sizes, V.Vf in the diameter ranges 20-30, 30-40, and >40 μm were smaller in HU10 than in WB10, and V.Seg in the diameter range >40 μm was smaller in HU10 than in WB10. In contrast, there was no difference in B.Vf between DFOHU5/10 and WB5/10 and in V.Vf between DFOHU10 and WB10, though B.Seg remained 86% smaller in DFOHU5 and 94% larger in DFOHU10 than in WB5/10, and B.Th and V.D were 23% and 14% lower in DFOHU10 than in WB10. Vessel size-specific V.Vf in the diameter ranges 10-20 and 20-30 μm was larger in DFOHU5 than in HU5. In conclusion, the enhanced angiogenic ingrowth mitigates the reduction in bone repair during mechanical unloading. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Gene Expression and Structural Skeletal Responses to Long-Duration Simulated Microgravity in Rats

NASA Technical Reports Server (NTRS)

Shirazi-Fard, Yasaman; Rael, Victoria E.; Torres, Samantha; Steczina, Sonette; Bryant, Sheenah; Tahimic, Candice; Globus, Ruth K.

2017-01-01

In this study, we aim to examine skeletal responses to simulated long-duration spaceflight (90 days) and weight-bearing recovery on bone loss using the ground-based hindlimb unloading (HU) model in adolescent (3-month old) male rats. We hypothesized that simulated microgravity leads to the temporal regulation of oxidative defense genes and pro-bone resorption factors, where there is a progression and eventual plateau; furthermore, early transient changes in these pathways precede skeletal adaptations.

Effects of local vibration on bone loss in -tail-suspended rats.

PubMed

Sun, L W; Luan, H Q; Huang, Y F; Wang, Y; Fan, Y B

2014-06-01

We investigated the effects of vibration (35 Hz, 45 Hz and 55 Hz) as countermeasure locally applied to unloading hind limbs on bone, muscle and Achilles tendon. 40 female Sprague Dawley rats were divided into 5 groups (n=8, each): tail-suspension (TS), TS plus 35 Hz/0.3 g vibration (TSV35), TS plus 45 Hz/0.3 g vibration (TSV45), TS plus 55 Hz/0.3 g vibration (TSV55) and control (CON). After 21 days, bone mineral density (BMD) and the microstructure of the femur and tibia were evaluated by μCT in vivo. The biomechanical properties of the femur and Achilles tendon were determined by a materials testing system. Ash weight of bone, isotonic contraction and wet weight of soleus were also investigated. 35 Hz and 45 Hz localized vibration were able to significantly ameliorate the decrease in trabecular BMD (expressed as the percentage change from TS, TSV35: 48.11%, TSV45: 31.09%), microstructure and ash weight of the femur and tibia induced by TS. Meanwhile, 35 Hz vibration significantly improved the biomechanical properties of the femur (57.24% bending rigidity and 41.66% Young's modulus vs. TS) and Achilles tendon (45.46% maximum load and 66.67% Young's modulus vs. TS). Additionally, Young's modulus of the femur was highly correlated with microstructural parameters. Localized vibration was useful for counteracting microgravity-induced musculoskeletal loss. In general, the efficacy of 35 Hz was better than 45 Hz or 55 Hz in tail-suspended rats. © Georg Thieme Verlag KG Stuttgart · New York.

Regulation of Bone Formation During Disuse by miRNA

NASA Technical Reports Server (NTRS)

Thomas, Nicholas; Choi, Catherine Y.; Alwood, Joshua S.

2016-01-01

Astronauts lose bone structure during long-duration spaceflight. These changes are due, in part, to insufficient bone formation by the osteoblast cells. Little is known about the role that small (approximately 22 nucleotide), non-coding micro-RNAs (miRNAs) play in the osteoblast response to microgravity. We hypothesize that osteoblast-lineage cells alter their miRNA status during microgravity exposure, contributing to impaired bone formation during weightlessness. To simulate weightlessness, female mice (C57BL/6, Charles River, 10 weeks of age, n = 6) were hindlimb unloaded for 12 days. Age-matched and normally ambulating mice served as controls (n=6). To assess the expression of miRNAs in skeletal tissue, the right and left tibia of the mice were collected ex vivo and cleaned of soft-tissue and marrow. Total RNA was collected from tibial bone and relative abundance was measured for miRNAs of interest using quantitative real time PCR array looking at 372 unique and well-characterized mature miRNAs using the delta-delta Ct method. Transcripts of interest were normalized to an average of 6 reference RNAs. Preliminary results show that hindlimb unloading decreased the expression of 14 miRNAs to less than 1.4-2.9X control levels and increased the expression of 5 miRNAs relative to the control mice greater than 1-2-1.5X (p less than 0.05, respectively). Using the miRSystem we assessed overlapping target genes predicted to be regulated by multiple members of the 19 differentially expressed miRNAs as well as in silico predicted targets of our individual miRNAs. Our miRSystem results indicated that a number of our differentially expressed miRNAs were regulators of genes related to the Wnt-Beta Catenin pathway-a known regulator of bone health-and, interestingly, the estrogen-mediated cell-cycle regulation pathway, which may indicate that simulated weightlessness induced systemic hormonal changes that contributed to bone loss. We plan to follow up these findings by measuring gene expression of miRNA-regulated genes within these two pathways with the aim of furthering our understanding of the function of miRNAs in the skeletal response to spaceflight.

Changes in bone structure and metabolism during simulated weightlessness: Endocrine and dietary factors

NASA Technical Reports Server (NTRS)

Halloran, B. P.; Wronski, T. J.

1985-01-01

The role of vitamin D, PTH and corticosterone in the skeletal alterations induced by simulated weightlessness was examined. The first objective was to determine if changes in the serum concentrations of Ca, P sub i, osteocalcin, 25-OH-D, 24,25(OH)2D or 1,25(OH)2D also occur following acute skeletal unloading. Animals were either suspended or pair fed for 2, 5, 7, 10, 12 and 15 days and the serum concentrations of Ca, P sub i, osteocalcin and the vitamin D metabolites measured. Bone histology was examined at day 5 after suspension. Acute skeletal unloading produced a transient hypercalcemia, a significant fall in serum osteocalcin and serum 1,25(OH)2D, a slight rise in serum 24,25(OH)2D, but did not affect the serum concentrations of P sub i or 25-OH-D. At the nadir in serum 1,25(OH)2D serum osteocalcin was reduced by 22%, osteoblast surface by 32% and longitudinal bone growth by 21%.

Simulating Bone Loss in Microgravity Using Mathematical Formulations of Bone Remodeling

NASA Technical Reports Server (NTRS)

Pennline, James A.

2009-01-01

Most mathematical models of bone remodeling are used to simulate a specific bone disease, by disrupting the steady state or balance in the normal remodeling process, and to simulate a therapeutic strategy. In this work, the ability of a mathematical model of bone remodeling to simulate bone loss as a function of time under the conditions of microgravity is investigated. The model is formed by combining a previously developed set of biochemical, cellular dynamics, and mechanical stimulus equations in the literature with two newly proposed equations; one governing the rate of change of the area of cortical bone tissue in a cross section of a cylindrical section of bone and one governing the rate of change of calcium in the bone fluid. The mechanical stimulus comes from a simple model of stress due to a compressive force on a cylindrical section of bone which can be reduced to zero to mimic the effects of skeletal unloading in microgravity. The complete set of equations formed is a system of first order ordinary differential equations. The results of selected simulations are displayed and discussed. Limitations and deficiencies of the model are also discussed as well as suggestions for further research.

A mechanism of bone tissue loss in monkeys (BION - 11).

NASA Astrophysics Data System (ADS)

Rodionova, N. V.; Oganov, V. S.

The elucidation of mechanisms of bone tissue loss under the spaceflight conditions remains an actual problem until now It was established that primary reactions to a mechanical stress evolve at the cellular level therefore the main attention of the researchers was aimed at studying bone tissue cells and their interactions With the use of electron microscopy we studied osteoblasts osteocytes osteoclasts and stromal cells in bioptats of the iliac bone crest from monkeys flown on board the satellite guillemotleft BION - 11 guillemotright during 2 weeks The flight samples were compared with the vivarium and simulation controls The functional state of cells was evaluated by the degree of development of organelles for specific biosyntheses rough endoplasmic reticulum Golgy complex nucleus state interrelation with a mineralized matrix The analysis of the obtained results and data of other authors Klein -- Nulend et al 2003 etc permits to suppose that the following sequence of cell interactions underlies the bone tissue loss during mechanical stress microgravity reaction of mechano-sensitive osteocytes to a mechanical stimulus consisting in enhancement of osteolytic processes in cells which results in a partial bone tissue loss along the local unloading Simultaneously the modulating signals are transmitted through a system of canals and processes towards active osteoblasts surface osteocytes and bone marrow stromal cells as well As a reply to a mechanical stimulus there occurs a reduction slowing down of proliferation

Effects of spaceflight and simulated weightlessness on longitudinal bone growth

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Zhang, M.; Evans, G. L.; Westerlind, K. C.; Cavolina, J. M.; Morey-Holton, E.; Turner, R. T.

2000-01-01

Indirect measurements have suggested that spaceflight impairs bone elongation in rats. To test this possibility, our laboratory measured, by the fluorochrome labeling technique, bone elongation that occurred during a spaceflight experiment. The longitudinal growth rate (LGR) in the tibia of rats in spaceflight experiments (Physiological Space Experiments 1, 3, and 4 and Physiological-Anatomical Rodent Experiment 3) and in two models of skeletal unloading (hind-limb elevation and unilateral sciatic neurotomy) were calculated. The effects of an 11 day spaceflight on gene expression of cartilage matrix proteins in rat growth plates were also determined by northern analysis and are reported for the first time in this study. Measurements of longitudinal growth indicate that skeletal unloading generally did not affect LGR, regardless of age, strain, gender, duration of unloading, or method of unloading. There was, however, one exception with 34% suppression in LGR detected in slow-growing, ovariectomized rats skeletally unloaded for 8 days by hind-limb elevation. This detection of reduced LGR by hind-limb elevation is consistent with changes in steady-state mRNA levels for type II collagen (-33%) and for aggrecan (-53%) that were detected in rats unloaded by an 11 day spaceflight. The changes detected in gene expression raise concern that spaceflight may result in changes in the composition of extracellular matrix, which could have a negative impact on conversion of growth-plate cartilage into normal cancellous bone by endochondral ossification.

VEGF Receptor 2 (VEGFR2) Activation Is Essential for Osteocyte Survival Induced by Mechanotransduction.

PubMed

de Castro, Luis F; Maycas, Marta; Bravo, Beatriz; Esbrit, Pedro; Gortazar, Arancha

2015-02-01

Mechanical loading plays a key role in bone formation and maintenance. While unloading induces osteocyte apoptosis and bone loss in vivo, mechanical stimuli prevents osteocyte death through a mechanism involving β-catenin accumulation and ERK nuclear translocation. Vascular endothelial growth factor (VEGF) has a crucial role in bone formation, but its interaction with osteocytes is not completely understood. Of interest, VEGF receptor 2 (VEGFR2) has recently been shown to mediate the mechanical response of endothelial cells. The present study aimed to evaluate the putative role of the VEGF system in osteocyte mechanosensing. We show that either short (10 min) mechanical stimulus by pulsatile fluid flow (FF) (10 dyn/cm(2), 8 Hz) or exogenous VEGF165 (6 ng/ml) similarly stimulated cell viability, ERK phosphorylation, and β-catenin membrane translocation. A VEGFR2 antagonist (SU5416) or transfection with specific VEGFR2 siRNAs (siVEGFR2) decreased these events. FF for 10 min increased VEGFR2 phosphorylation at both Tyr-1059 and Tyr-1175; an effect that was mimicked by VEGF165 but was unaffected by a VEGF neutralizing antibody. Subsequently (at 6 h), this mechanical stimulus induced VEGF gene overexpression, which was prevented by siVEGFR2 transfection. Depletion of the structural protein caveolin-1 by using siRNA technology impaired FF-induced VEGFR2 phosphorylation. In conclusion, these in vitro findings point to caveolin-1-dependent VEGFR2 activation as an important mechanism whereby mechanical stimuli promote osteocyte viability. © 2014 Wiley Periodicals, Inc.

Mechanical unloading reduces microtubule actin crosslinking factor 1 expression to inhibit β-catenin signaling and osteoblast proliferation.

PubMed

Yin, Chong; Zhang, Yan; Hu, Lifang; Tian, Ye; Chen, Zhihao; Li, Dijie; Zhao, Fan; Su, Peihong; Ma, Xiaoli; Zhang, Ge; Miao, Zhiping; Wang, Liping; Qian, Airong; Xian, Cory J

2018-07-01

Mechanical unloading was considered a major threat to bone homeostasis, and has been shown to decrease osteoblast proliferation although the underlying mechanism is unclear. Microtubule actin crosslinking factor 1 (MACF1) is a cytoskeletal protein that regulates cellular processes and Wnt/β-catenin pathway, an essential signaling pathway for osteoblasts. However, the relationship between MACF1 expression and mechanical unloading, and the function and the associated mechanisms of MACF1 in regulating osteoblast proliferation are unclear. This study investigated effects of mechanical unloading on MACF1 expression levels in cultured MC3T3-E1 osteoblastic cells and in femurs of mice with hind limb unloading; and it also examined the role and potential action mechanisms of MACF1 in osteoblast proliferation in MACF1-knockdown, overexpressed or control MC3T3-E1 cells treated with or without the mechanical unloading condition. Results showed that the mechanical unloading condition inhibited osteoblast proliferation and MACF1 expression in MC3T3-E1 osteoblastic cells and mouse femurs. MACF1 knockdown decreased osteoblast proliferation, while MACF1 overexpression increased it. The inhibitory effect of mechanical unloading on osteoblast proliferation also changed with MACF1 expression levels. Furthermore, MACF1 was found to enhance β-catenin expression and activity, and mechanical unloading decreased β-catenin expression through MACF1. Moreover, β-catenin was found an important regulator of osteoblast proliferation, as its preservation by treatment with its agonist lithium attenuated the inhibitory effects of MACF1-knockdown or mechanical unloading on osteoblast proliferation. Taken together, mechanical unloading decreases MACF1 expression, and MACF1 up-regulates osteoblast proliferation through enhancing β-catenin signaling. This study has thus provided a mechanism for mechanical unloading-induced inhibited osteoblast proliferation. © 2017 Wiley Periodicals, Inc.

Mimicking the effects of spaceflight on bone: Combined effects of disuse and chronic low-dose rate radiation exposure on bone mass in mice

NASA Astrophysics Data System (ADS)

Yu, Kanglun; Doherty, Alison H.; Genik, Paula C.; Gookin, Sara E.; Roteliuk, Danielle M.; Wojda, Samantha J.; Jiang, Zhi-Sheng; McGee-Lawrence, Meghan E.; Weil, Michael M.; Donahue, Seth W.

2017-11-01

During spaceflight, crewmembers are subjected to biomechanical and biological challenges including microgravity and radiation. In the skeleton, spaceflight leads to bone loss, increasing the risk of fracture. Studies utilizing hindlimb suspension (HLS) as a ground-based model of spaceflight often neglect the concomitant effects of radiation exposure, and even when radiation is accounted for, it is often delivered at a high-dose rate over a very short period of time, which does not faithfully mimic spaceflight conditions. This study was designed to investigate the skeletal effects of low-dose rate gamma irradiation (8.5 cGy gamma radiation per day for 20 days, amounting to a total dose of 1.7 Gy) when administered simultaneously to disuse from HLS. The goal was to determine whether continuous, low-dose rate radiation administered during disuse would exacerbate bone loss in a murine HLS model. Four groups of 16 week old female C57BL/6 mice were studied: weight bearing + no radiation (WB+NR), HLS + NR, WB + radiation exposure (WB+RAD), and HLS+RAD. Surprisingly, although HLS led to cortical and trabecular bone loss, concurrent radiation exposure did not exacerbate these effects. Our results raise the possibility that mechanical unloading has larger effects on the bone loss that occurs during spaceflight than low-dose rate radiation.

Hindlimb unloading has a greater effect on cortical compared with cancellous bone in mature female rats

NASA Technical Reports Server (NTRS)

Allen, Matthew R.; Bloomfield, Susan A.

2003-01-01

This study was designed to determine the effects of 28 days of hindlimb unloading (HU) on the mature female rat skeleton. In vivo proximal tibia bone mineral density and geometry of HU and cage control (CC) rats were measured with peripheral quantitative computed tomography (pQCT) on days 0 and 28. Postmortem pQCT, histomorphometry, and mechanical testing were performed on tibiae and femora. After 28 days, HU animals had significantly higher daily food consumption (+39%) and lower serum estradiol levels (-49%, P = 0.079) compared with CC. Proximal tibia bone mineral content and cortical bone area significantly declined over 28 days in HU animals (-4.0 and 4.8%, respectively), whereas total and cancellous bone mineral densities were unchanged. HU animals had lower cortical bone formation rates and mineralizing surface at tibial midshaft, whereas differences in similar properties were not detected in cancellous bone of the distal femur. These results suggest that cortical bone, rather than cancellous bone, is more prominently affected by unloading in skeletally mature retired breeder female rats.

Impact of skeletal unloading on bone formation: Role of systemic and local factors

NASA Astrophysics Data System (ADS)

Bikle, Daniel D.; Halloran, Bernard P.; Morey-Holton, Emily

We have developed a model of skeletal unloading using growing rats whose hindlimbs are unweighted by tail suspension. The bones in the hindlimbs undergo a transient cessation of bone growth; when reloaded bone formation is accelerated until bone mass is restored. These changes do not occur in the normally loaded bones of the forelimbs. Associated with the fall in bone formation is a fall in 1,25(OH) 2D 3 production and osteocalcin levels. In contrast, no changes in parathyroid hormone, calcium, or corticosterone levels are seen. To examine the role of locally produced growth factors, we have measured the mRNA and protein levels of insulin like growth factor-1 (IGF-1) in bone during tail suspension. Surprisingly, both the mRNA and protein levels of IGF-1 increase during tail suspension as bone formation is reduced. Furthermore, the bones in the hindlimbs of the suspended animals develop a resistance to the growth promoting effects of both growth hormone and IGF-1 when given parenterally. Thus, the cessation of bone growth with skeletal unloading is apparently associated with a resistance to rather than failure to produce local growth factors. The cause of this resistance remains under active investigation.

Polar bears (Ursus maritimus), the most evolutionary advanced hibernators, avoid significant bone loss during hibernation.

PubMed

Lennox, Alanda R; Goodship, Allen E

2008-02-01

Some hibernating animals are known to reduce muscle and bone loss associated with mechanical unloading during prolonged immobilisation,compared to humans. However, here we show that wild pregnant polar bears (Ursus maritimus) are the first known animals to avoid significant bone loss altogether, despite six months of continuous hibernation. Using serum biochemical markers of bone turnover, we showed that concentrations for bone resorption are not significantly increased as a consequence of hibernation in wild polar bears. This is in sharp contrast to previous studies on other hibernating species, where for example, black bears (Ursus americanus), show a 3-4 fold increase in serum bone resorption concentrations posthibernation,and must compensate for this loss through rapid bone recovery on remobilisation, to avoid the risk of fracture. In further contrast to black bears, serum concentrations of bone formation markers were highly significantly increased in pregnant female polar bears compared to non-pregnant,thus non-hibernating females both prior to and after hibernation. However, bone formation concentrations in new mothers were significantly reduced compared to pre-hibernation concentrations. The de-coupling of bone turnover in favour of bone formation prior to hibernation, suggests that wild polar bears may posses a unique physiological mechanism for building bone in protective preparation against expected osteopenia associated with disuse,starvation, and hormonal drives to mobilise calcium for reproduction, during hibernation. Understanding this physiological mechanism could have profound implications for a natural solution for the prevention of osteoporosis in animals subjected to captivity with inadequate space for exercise,humans subjected to prolonged bed rest while recovering from illness, or astronauts exposed to antigravity during spaceflight.© 2008 Elsevier Inc. All rights reserved.

PULSED FOCUSED ULTRASOUND TREATMENT OF MUSCLE MITIGATES PARALYSIS-INDUCED BONE LOSS IN THE ADJACENT BONE: A STUDY IN A MOUSE MODEL

PubMed Central

Poliachik, Sandra L.; Khokhlova, Tatiana D.; Wang, Yak-Nam; Simon, Julianna C.; Bailey, Michael R.

2015-01-01

Bone loss can result from bed rest, space flight, spinal cord injury or age-related hormonal changes. Current bone loss mitigation techniques include pharmaceutical interventions, exercise, pulsed ultrasound targeted to bone and whole body vibration. In this study, we attempted to mitigate paralysis-induced bone loss by applying focused ultrasound to the midbelly of a paralyzed muscle. We employed a mouse model of disuse that uses onabotulinumtoxinA-induced paralysis, which causes rapid bone loss in 5 d. A focused 2 MHz transducer applied pulsed exposures with pulse repetition frequency mimicking that of motor neuron firing during walking (80 Hz), standing (20 Hz), or the standard pulsed ultrasound frequency used in fracture healing (1 kHz). Exposures were applied daily to calf muscle for 4 consecutive d. Trabecular bone changes were characterized using micro-computed tomography. Our results indicated that application of certain focused pulsed ultrasound parameters was able to mitigate some of the paralysis-induced bone loss. PMID:24857416

Dihydroartemisinin attenuates lipopolysaccharide-induced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway

PubMed Central

Dou, C; Ding, N; Xing, J; Zhao, C; Kang, F; Hou, T; Quan, H; Chen, Y; Dai, Q; Luo, F; Xu, J; Dong, S

2016-01-01

Dihydroartemisinin (DHA) is a widely used antimalarial drug isolated from the plant Artemisia annua. Recent studies suggested that DHA has antitumor effects utilizing its reactive oxygen species (ROS) yielding mechanism. Here, we reported that DHA is inhibitory on lipopolysaccharide (LPS)-induced osteoclast (OC) differentiation, fusion and bone-resorption activity in vitro. Intracellular ROS detection revealed that DHA could remarkably increase ROS accumulation during LPS-induced osteoclastogenesis. Moreover, cell apoptosis was also increased by DHA treatment. We found that DHA-activated caspase-3 increased Bax/Bcl-2 ratio during LPS-induced osteoclastogenesis. Meanwhile, the translocation of apoptotic inducing factor (AIF) and the release of cytochrome c from the mitochondria into the cytosol were observed, indicating that ROS-mediated mitochondrial dysfunction is crucial in DHA-induced apoptosis during LPS-induced osteoclastogenesis. In vivo study showed that DHA treatment decreased OC number, prevents bone loss, rescues bone microarchitecture and restores bone strength in LPS-induced bone-loss mouse model. Together, our findings indicate that DHA is protective against LPS-induced bone loss through apoptosis induction of osteoclasts via ROS accumulation and the mitochondria-dependent apoptosis pathway. Therefore, DHA may be considered as a new therapeutic candidate for treating inflammatory bone loss. PMID:27031959

Mimicking the effects of spaceflight on bone: Combined effects of disuse and chronic low-dose rate radiation exposure on bone mass in mice.

PubMed

Yu, Kanglun; Doherty, Alison H; Genik, Paula C; Gookin, Sara E; Roteliuk, Danielle M; Wojda, Samantha J; Jiang, Zhi-Sheng; McGee-Lawrence, Meghan E; Weil, Michael M; Donahue, Seth W

2017-11-01

During spaceflight, crewmembers are subjected to biomechanical and biological challenges including microgravity and radiation. In the skeleton, spaceflight leads to bone loss, increasing the risk of fracture. Studies utilizing hindlimb suspension (HLS) as a ground-based model of spaceflight often neglect the concomitant effects of radiation exposure, and even when radiation is accounted for, it is often delivered at a high-dose rate over a very short period of time, which does not faithfully mimic spaceflight conditions. This study was designed to investigate the skeletal effects of low-dose rate gamma irradiation (8.5 cGy gamma radiation per day for 20 days, amounting to a total dose of 1.7 Gy) when administered simultaneously to disuse from HLS. The goal was to determine whether continuous, low-dose rate radiation administered during disuse would exacerbate bone loss in a murine HLS model. Four groups of 16 week old female C57BL/6 mice were studied: weight bearing + no radiation (WB+NR), HLS + NR, WB + radiation exposure (WB+RAD), and HLS+RAD. Surprisingly, although HLS led to cortical and trabecular bone loss, concurrent radiation exposure did not exacerbate these effects. Our results raise the possibility that mechanical unloading has larger effects on the bone loss that occurs during spaceflight than low-dose rate radiation. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Contribution of dietary and loading changes to the effects of suspension on mouse femora

NASA Technical Reports Server (NTRS)

Simske, S. J.; Broz, J. J.; Fleet, M. L.; Schmeister, T. A.; Gayles, E. C.; Luttges, M. W.; Spooner, B. S. (Principal Investigator)

1994-01-01

The present study assessed the contributions of feeding changes and unloading to the overall measured effects of 2-wk hindlimb (Tail) suspension on the mouse femora. Feeding changes were addressed by considering the effects of matched feeding among suspended and control mice. The effects of hind limb unloading were considered by comparing suspended mice to mice equipped identically (though not suspended) and matched-fed. The feeding and unloading aspects of suspension appear to cause distinctly differing effects on the stereotypic modeling of the femora. Matched-feeding was accompanied by increased resorption surface in comparison to suspended mice, while unloading led to reduced bone formation at the mid-diaphysis of the femora. Reduced mineral content was observed in the bones of suspended mice when compared to the other mice groups, but without increased resorption surface. Thus, the unloading aspects of the antiorthostatic suspension protocol apparently causes reduced formation and mineralization in the femur.

Skeletal Phenotype of Transgenic Mice Expressing the Beta1 Integrin Cytoplasmic Tail In Osteoblasts

NASA Technical Reports Server (NTRS)

Globus, R. K.; vanderMeulen, M. C. H.; Damsky, D.; Kim, J.-B.; Amblard, D.; Amblard, D.; Nishimura, Y.; Almeida, E.; Iwaniec, U. T.; Wronski, T. J.;

Deoxypyridinoline in the Urine of Rats with Unloaded Hindlimbs

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Navidi, M.; Wren, J.; Holton, Emily M. (Technical Monitor)

1997-01-01

The urinary excretion of deoxypyridinoline (U-Dpd), a nonreducible collagen crosslink in bone released by osteoclastic activity, is thought to be an accurate marker of bone resorption. The role of increased resorption in the osteopenia of a space flight model which unloads the hindlimbs by suspending the tail is controversial. To assess skeletal resorption in the model we measured U-Dpd (Pyrilinks-D, Metro Biosystems, Inc.) in serial 24 hour urine specimens collected from 250 a (Y) and 450 a (M) male rats with unloaded hindlimbs for four weeks. Both groups of rats were fed AIN76 diets with calcium restricted to 0.2% in Y and to 0.1 % in M. Blood was obtained after 28 days for parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25-D) and alkaline phosphatase (Alkptase). Basal U-Dpd was higher and more variable in Y than M (475+/-200 vs 67+/-9, nM/mM creatinine, p<.001). Repeated measures ANOVA in Y revealed decreases in U-Dpd, 36% in control (C) and 24% in unloaded (S) rats (p<.005). There was a nadir in YS on the 14th day not observed in YC (p<.05). U-Dpd in MC showed no change, but increased in MS by the 14th day and remained elevated. At the end of the experiment, body weights in both Y and M were less in S than C (337+/-16 vs 306+/-12g and 485+/-10 vs 461+/-6g, p=.002). Bill was inversely related to U-Dpd only in M (r=0.699, p=.024). PTH, similar in C and S in Y (52+/-15 vs 42+/-7pg/ml, NS) and M (68+/-13 vs 61+/-12, NS), was unrelated to U-Dpd. 1,25-D tended toward higher values in YC than YS (197+/-103 vs 119+/-30, NS) and correlated with U-Dpd (0.773, p=.015). Alkptase, 1.3 times higher in Y than M, was similar in C and S at the end of unloading. These findings indicate that bone resorption, as reflected by U-Dpd, is suppressed in young and stimulated in mature rats exposed to a space flight model. U-Dpd reflects reduced growth from the diet change in young control and experimental rats and loss of Bill in mature animals exposed to the space flight model, 2 situations with opposite effects on bone resorption.

Mechanically induced alterations in cultured skeletal muscle growth

NASA Technical Reports Server (NTRS)

Vandenburgh, H. H.; Hatfaludy, S.; Karlisch, P.; Shansky, J.

1991-01-01

Model systems are available for mechanically stimulating cultured skeletal muscle cells by passive tensile forces which simulate those found in vivo. When applied to embryonic muscle cells in vitro these forces induce tissue organogenesis, metabolic adaptations, and muscle cell growth. The mechanical stimulation of muscle cell growth correlates with stretch-induced increases in the efflux of prostaglandins PGE2 and PGF2(alpha) in a time and frequency dependent manner. These prostaglandins act as mechanical 'second messengers' regulating skeletal muscle protein turnover rates. Since they also effect bone remodelling in response to tissue loading and unloading, secreted prostaglandins may serve as paracrine growth factors, coordinating the growth rates of muscle and bone in response to external mechanical forces. Cell culture model systems will supplement other models in understanding mechanical transduction processes at the molecular level.

Is Animal Age a Factor In the Response of Bone to Spaceflight?

NASA Technical Reports Server (NTRS)

Morey-Holton, E. R.; Garetto, L. P.; Doty, S. B.; Halloran, B. P.; Turner, R. T.; Dalton, Bonnie (Technical Monitor)

2002-01-01

The rodent bone response to spaceflight may be influenced by a multitude of actors including flight duration, strain, and housing. Review of bone formation rates during spaceflight suggests that age may also play a role in the response. Weanling rats show fewer bone changes than older rats. To determine if the long bones of weanling rats were insensitive to weight-bearing, a hindlimb unloading experiment was conducted simultaneously with a 9d shuttle flight in 34d old group-housed male rats. All animals were injected with bone markers 7d and 1d before flight and euthanized at landing, 24hr, and 72hr following recovery. If no differences in body weight, bone length, or bone formation at the tibiofibular junction were noted at the different time points, data were combined for each group. No significant differences in body weight were found at any time period among the groups. The humerus, tibia, and femur elongated significantly during the flight period with no difference in lengths between groups at the end of the flight period. The group-housed flight rats showed no change in cortical bone formation rate compared to preflight values, flight controls, or vivarium controls. However, the hindlimb unloading group showed a significant 30% decrease in bone formation rate compared to all other groups. Individually-housed 38d old animals flown for 14d showed approx. 10% suppression of cortical growth. We speculate that the mechanical threshold required for cross-sectional bone growth is reached in group-house weanling rats during spaceflight, perhaps, through physical interactions, and that the weanling animals are sensitive to loading. However, the threshold is not fully reached in either singly-housed flight or hindlimb unloaded weanling rats. Older singly-housed flight animals appear to show equal or greater bone changes compared to hindlimb unloaded rats. We conclude that age, flight duration, strain, and housing have important roles in rodent skeletal responses to spaceflight.

Polymethoxy flavonoids, nobiletin and tangeretin, prevent lipopolysaccharide-induced inflammatory bone loss in an experimental model for periodontitis.

PubMed

Tominari, Tsukasa; Hirata, Michiko; Matsumoto, Chiho; Inada, Masaki; Miyaura, Chisato

2012-01-01

Nobiletin, a polymethoxy flavonoid (PMF), inhibits systemic bone resorption and maintains bone mass in estrogen-deficient ovariectomized mice. This study examined the anti-inflammatory effects of PMFs, nobiletin, and tangeretin on lipopolysaccharide (LPS)-induced bone resorption. Nobiletin and tangeretin suppressed LPS-induced osteoclast formation and bone resorption and suppressed the receptor activator of NFκB ligand-induced osteoclastogenesis in RAW264.7 macrophages. Nobiletin clearly restored the alveolar bone mass in a mouse experimental model for periodontitis by inhibiting LPS-induced bone resorption. PMFs may therefore provide a new therapeutic approach for periodontal bone loss.

The Hematopoietic Stem Cell Therapy for Exploration of Deep Space

NASA Astrophysics Data System (ADS)

Ohi, Seigo; Roach, Allana-Nicole; Ramsahai, Shweta; Kim, Bak C.; Fitzgerald, Wendy; Riley, Danny A.; Gonda, Steven R.

2004-02-01

Astronauts experience severe/invasive disorders caused by space environments. These include hematological and cardiac abnormalities, bone and muscle losses, immunodeficiency, neurological disorders and cancer. Exploiting the extraordinary plasticity of hematopoietic stem cells (HSCs), which differentiate not only to all types of blood cells, but also to various tissues, including muscle, bone, skin, liver, and neuronal cells, we advanced a hypothesis that some of the space-caused disorders might be amenable to hematopoietic stem cell therapy (HSCT) so as to maintain astronauts' homeostasis. If this were achievable, the HSCT could promote human exploration of deep space. Using mouse models of human anemia (β-thalassemia) and spaceflight (hindlimb suspension unloading system), we have obtained feasibility results of HSCT for space anemia, muscle loss, and immunodeficiency. For example, the β-thalassemic mice were successfully transplanted with isologous HSCs, resulting in chimerism of hemoglobin species and alleviation of the hemoglobinopathy. In the case of HSCT for muscle loss, β-galactosidase-marked HSCs, which were prepared from β-galactosidase-transgenic mice, were detected by the X-gal wholemount staining procedure in the hindlimbs of unloaded mice following transplantation. Histochemical and physical analyses indicated structural contribution of HSCs to the muscle. To investigate HSCT for immunodeficiency, β-galactosidase-transformed Escherichia coli was used as the reporter bacteria, and infected to control and the hindlimb suspended mice. Results of the X-gal stained tissues indicated that the HSCT could help eliminate the E. coli infection. In an effort to facilitate the HSCT in space, growth of HSCs has been optimized in the NASA Rotating Wall Vessel (RWV) culture systems, including Hydrodynamic Focusing Bioreactor (HFB).

Network Analysis Implicates Alpha-Synuclein (Snca) in the Regulation of Ovariectomy-Induced Bone Loss

PubMed Central

Calabrese, Gina; Mesner, Larry D.; Foley, Patricia L.; Rosen, Clifford J.; Farber, Charles R.

2016-01-01

The postmenopausal period in women is associated with decreased circulating estrogen levels, which accelerate bone loss and increase the risk of fracture. Here, we gained novel insight into the molecular mechanisms mediating bone loss in ovariectomized (OVX) mice, a model of human menopause, using co-expression network analysis. Specifically, we generated a co-expression network consisting of 53 gene modules using expression profiles from intact and OVX mice from a panel of inbred strains. The expression of four modules was altered by OVX, including module 23 whose expression was decreased by OVX across all strains. Module 23 was enriched for genes involved in the response to oxidative stress, a process known to be involved in OVX-induced bone loss. Additionally, module 23 homologs were co-expressed in human bone marrow. Alpha synuclein (Snca) was one of the most highly connected “hub” genes in module 23. We characterized mice deficient in Snca and observed a 40% reduction in OVX-induced bone loss. Furthermore, protection was associated with the altered expression of specific network modules, including module 23. In summary, the results of this study suggest that Snca regulates bone network homeostasis and ovariectomy-induced bone loss. PMID:27378017

Effect of the Intermittent Hypoxia on the Bone Tissue State After Microgravitation Modeling

NASA Astrophysics Data System (ADS)

Berezovskiy, V. A.; Litovka, I. G.; Chaka, H. G.; Magomedov, S.; Mehed, N. V.

The authors studied the influence of low PO2 under normal atmospheric pressure on the Ca and P metabolism, bone remodeling markers, and biomechanical properties of the femura bone in rats with their hind limbs unloaded. A hypoxic gas mixture (HGM) was given in intermittent regime A and B for 8 hours/day during 28 days. It was shown that regime A slows down the development of osteopenia and may be used in complex with other rehabilitation procedures for preventing the unloading osteopenia.

Associated among endocrine, inflammatory, and bone markers, body composition and weight loss induced bone loss

USDA-ARS?s Scientific Manuscript database

Weight loss reduces co-¬morbidities of obesity but decreases bone mass. Our aims were to determine whether adequate dairy intake could prevent weight loss related bone loss and to evaluate the contribution of energy-related hormones and inflammatory markers to bone metabolism. Overweight and obese w...

In Vivo Hypobaric Hypoxia Performed During the Remodeling Process Accelerates Bone Healing in Mice

PubMed Central

Durand, Marjorie; Collombet, Jean-Marc; Frasca, Sophie; Begot, Laurent; Lataillade, Jean-Jacques; Le Bousse-Kerdilès, Marie-Caroline

2014-01-01

We investigated the effects of respiratory hypobaric hypoxia on femoral bone-defect repair in mice because hypoxia is believed to influence both mesenchymal stromal cell (MSC) and hematopoietic stem cell mobilization, a process involved in the bone-healing mechanism. To mimic conditions of non-weight-bearing limb immobilization in patients suffering from bone trauma, our hypoxic mouse model was further subjected to hind-limb unloading. A hole was drilled in the right femur of adult male C57/BL6J mice. Four days after surgery, mice were subjected to hind-limb unloading for 1 week. Seven days after surgery, mice were either housed for 4 days in a hypobaric room (FiO2 at 10%) or kept under normoxic conditions. Unsuspended control mice were housed in either hypobaric or normoxic conditions. Animals were sacrificed on postsurgery day 11 to allow for collection of both contralateral and lesioned femurs, blood, and spleen. As assessed by microtomography, delayed hypoxia enhanced bone-healing efficiency by increasing the closing of the cortical defect and the newly synthesized bone volume in the cavity by +55% and +35%, respectively. Proteome analysis and histomorphometric data suggested that bone-repair improvement likely results from the acceleration of the natural bone-healing process rather than from extended mobilization of MSC-derived osteoprogenitors. Hind-limb unloading had hardly any effect beyond delayed hypoxia-enhanced bone-healing efficiency. PMID:24944208

Exploring the effect of East Antarctic ice mass loss on GIA-induced horizontal bedrock motions

NASA Astrophysics Data System (ADS)

Konfal, S. A.; Whitehouse, P. L.; Hermans, T.; van der Wal, W.; Wilson, T. J.; Bevis, M. G.; Kendrick, E. C.; Dalziel, I.; Smalley, R., Jr.

2017-12-01

Ice history inputs used in Antarctic models of GIA include major centers of ice mass loss in West Antarctica. In the Transantarctic Mountains (TAM) region spanning the boundary between East and West Antarctica, horizontal crustal motions derived from GPS observations from the Antarctic Network (ANET) component of the Polar Earth Observing Network (POLENET) are towards these West Antarctic ice mass centers, opposite to the pattern of radial crustal motion expected in an unloading scenario. We investigate alternative ice history and earth structure inputs to GIA models in an attempt to reproduce observed crustal motions in the region. The W12 ice history model is altered to create scenarios including ice unloading in the Wilkes Subglacial Basin based on available glaciological records. These altered ice history models, along with the unmodified W12 ice history model, are coupled with 60 radially varying (1D) earth model combinations, including approximations of optimal earth profiles identified in published GIA models. The resulting model-predicted motions utilizing both the modified and unmodified ice history models fit ANET GPS-derived crustal motions in the northern TAM region for a suite of earth model combinations. Further south, where the influence of simulated Wilkes unloading is weakest and West Antarctic unloading is strongest, observed and predicted motions do not agree. The influence of simulated Wilkes ice unloading coupled with laterally heterogeneous earth models is also investigated. The resulting model-predicted motions do not differ significantly between the original W12 and W12 with simulated Wilkes unloading ice histories.

Effect of Eukarion-134 on Akt-mTOR signalling in the rat soleus during 7 days of mechanical unloading.

PubMed

Kuczmarski, J Matthew; Hord, Jeff M; Lee, Yang; Guzzoni, Vinicius; Rodriguez, Dinah; Lawler, Matthew S; Garcia-Villatoro, Erika L; Holly, Dylan; Ryan, Patrick; Falcon, Kristian; Garcia, Marcela; Janini Gomes, Mariana; Fluckey, James D; Lawler, John M

2018-04-01

What is the central question of this study? Translocation of nNOSμ initiates catabolic signalling via FoxO3a and skeletal muscle atrophy during mechanical unloading. Recent evidence suggests that unloading-induced muscle atrophy and FoxO3a activation are redox sensitive. Will a mimetic of superoxide dismutase and catalase (i.e. Eukarion-134) also mitigate suppression of the Akt-mTOR pathway? What is the main finding and its importance? Eukarion-134 rescued Akt-mTOR signalling and sarcolemmal nNOSμ, which were linked to protection against the unloading phenotype, muscle fibre atrophy and partial fibre-type shift from slow to fast twitch. The loss of nNOSμ from the sarcolemma appears crucial to Akt phosphorylation and is redox sensitive, although the mechanisms remain unresolved. Mechanical unloading stimulates rapid changes in skeletal muscle morphology, characterized by atrophy of muscle fibre cross-sectional area and a partial fibre-type shift from slow to fast twitch. Recent studies revealed that oxidative stress contributes to activation of forkhead box O3a (FoxO3a), proteolytic signalling and unloading-induced muscle atrophy via translocation of the μ-splice variant of neuronal nitric oxide synthase (nNOSμ) and activation of FoxO3a. There is limited understanding of the role of reactive oxygen species in the Akt-mammalian target of rapamycin (mTOR) pathway signalling during unloading. We hypothesized that Eukarion-134 (EUK-134), a mimetic of the antioxidant enzymes superoxide dismutase and catalase, would protect Akt-mTOR signalling in the unloaded rat soleus. Male Fischer 344 rats were separated into the following three study groups: ambulatory control (n = 11); 7 days of hindlimb unloading + saline injections (HU, n = 11); or 7 days of HU + EUK-134; (HU + EUK-134, n = 9). EUK-134 mitigated unloading-induced dephosphorylation of Akt, as well as FoxO3a, in the soleus. Phosphorylation of mTOR in the EUK-treated HU rats was not different from that in control animals. However, EUK-134 did not significantly rescue p70S6K phosphorylation. EUK-134 attenuated translocation of nNOSμ from the membrane to the cytosol, reduced nitration of tyrosine residues and suppressed upregulation of caveolin-3 and dysferlin. EUK-134 ameliorated HU-induced remodelling, atrophy of muscle fibres and the 12% increase in type II myosin heavy chain-positive fibres. Attenuation of the unloaded muscle phenotype was associated with decreased reactive oxygen species, as assessed by ethidium-positive nuclei. We conclude that oxidative stress affects Akt-mTOR signalling in unloaded skeletal muscle. Direct linkage of abrogation of nNOSμ translocation with Akt-mTOR signalling during unloading is the subject of future investigation. © 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.

Risedronate Prevents Early Radiation-Induced Osteoporosis in Mice at Multiple Skeletal Locations

PubMed Central

Willey, Jeffrey S.; Livingston, Eric W.; Robbins, Michael E.; Bourland, J. Daniel; Tirado-Lee, Leidamarie; Smith-Sielicki, Hope; Bateman, Ted A.

2009-01-01

Introduction Irradiation of normal, non-malignant bone during cancer therapy can lead to atrophy and increased risk of fracture at several skeletal sites, particularly the hip. This bone loss has been largely attributed to damaged osteoblasts. Little attention has been given to increased bone resorption as a contributor to radiation-induced osteoporosis. Our aims were to identify if radiation increases bone resorption resulting in acute bone loss, and if bone loss could be prevented by administering risedronate. Methods Twenty-week old female C57BL/6 mice were either: not irradiated and treated with placebo (NR+PL); whole-body irradiated with 2 Gy X-rays and treated with placebo (IR+PL); or irradiated and treated with risedronate (IR+RIS; 30μg/kg every other day). Calcein injections were administered 7 and 2 days before sacrifice. Bones were collected 1, 2, and 3 weeks after exposure. MicroCT analysis was performed at 3 sites: proximal tibial metaphysis; distal femoral metaphysis; and the body of the 5th lumbar vertebra (L5). Osteoclasts were identified from TRAP-stained histological sections. Dynamic histomorphometry of cortical and trabecular bone was performed. Circulating TRAP5b and osteocalcin concentrations were quantified. Results In animals receiving IR+PL, significant (P < 0.05) reduction in trabecular volume fraction relative to non-irradiated controls was observed at all three skeletal sites and time points. Likewise, radiation-induced loss of connectivity and trabecular number relative to NR+PL were observed at all skeletal sites throughout the study. Bone loss primarily occurred during the first week post-exposure. Trabecular and endocortical bone formation was not reduced until Week 2. Loss of bone volume was absent in animals receiving IR+RIS. Histology indicated greater osteoclast numbers at Week 1 within IR+PL mice. Serum TRAP5b concentration was increased in IR+PL mice only at Week 1 compared to NR+PL (P = 0.05). Risedronate treatment prevented the radiation-induced increase in osteoclast number, surface, and TRAP5b. Conclusion This study demonstrated a rapid loss of trabecular bone at several skeletal sites after whole-body irradiation. Changes were accompanied by an increase in osteoclast number and serum markers of bone loss. Risedronate entirely prevented bone loss, providing further evidence that an increase in bone resorption likely caused this radiation-induced bone loss. PMID:19747571

Repression of osteoblast maturation by ERRα accounts for bone loss induced by estrogen deficiency.

PubMed

Gallet, Marlène; Saïdi, Soraya; Haÿ, Eric; Photsavang, Johann; Marty, Caroline; Sailland, Juliette; Carnesecchi, Julie; Tribollet, Violaine; Barenton, Bruno; Forcet, Christelle; Birling, Marie-Christine; Sorg, Tania; Chassande, Olivier; Cohen-Solal, Martine; Vanacker, Jean-Marc

2013-01-01

ERRα is an orphan member of the nuclear receptor family, the complete inactivation of which confers resistance to bone loss induced by ageing and estrogen withdrawal to female mice in correlation with increased bone formation in vivo. Furthermore ERRα negatively regulates the commitment of mesenchymal cells to the osteoblast lineage ex vivo as well as later steps of osteoblast maturation. We searched to determine whether the activities of ERRα on osteoblast maturation are responsible for one or both types of in vivo induced bone loss. To this end we have generated conditional knock out mice in which the receptor is normally present during early osteoblast differentiation but inactivated upon osteoblast maturation. Bone ageing in these animals was similar to that observed for control animals. In contrast conditional ERRαKO mice were completely resistant to bone loss induced by ovariectomy. We conclude that the late (maturation), but not early (commitment), negative effects of ERRα on the osteoblast lineage contribute to the reduced bone mineral density observed upon estrogen deficiency.

S-Ketoprofen Inhibits Tenotomy-Induced Bone Loss and Dynamics in Weanling Rats

NASA Technical Reports Server (NTRS)

Zeng, Q. Q.; Jee, W. S. S.; Ke, H. Z.; Wechter, W. J.

1993-01-01

The objects of this study were to determine whether S-ketoprofen, a non-steroidal anti-inflammatory drug (NSAID), can prevent immobilization (tenotomy)-induced bone loss in weanling rats. Forty five 4 week-old Sprague-Dawley female rats were either sham-operated or subjected to knee tenotomy and treated simultaneously with 0, 0.02, 0.1, 0.5 or 2.5 mg of S-ketoprofen/kg per day for 21 days. We then studied double-fluorescent labeled proximal tibial longitudinal sections and tibial shaft cross sections using static and dynamic histomorphometry. Less cancellous bone mass in proximal tibial metaphyses was found in tenotomized controls than in basal (36%) and sham-operated (54%) controls. This was due to the inhibition of age-related bone gain and induced bone loss due to increased bone resorption and decreased bone formation. S-ketoprofen prevented both the inhibition of age-related bone gain and the stimulation of bone loss at the 2.5 mg/kg per day dose level, while it only prevented bone loss at the 0.5 mg/kg dose levels. In cancellous bone, dynamic histomorphometry showed that S-ketoprofen prevented the tenotomy induced decrease in bone formation and increase in bone resorption. In the tibial shaft, tenotomy inhibited the enlargement of total tissue area by depressing periosteal bone formation, and thus inhibited age-related cortical bone gain. S-ketoprofen treatment did not prevent this change at all dose levels, but reduced marrow cavity area to increase cortical bone area at the 0.1, 0.5 and 2.5 mg/kg per dose levels compared to tenotomy controls. However, the cortical bone area in the 0.1 and 0.5 mg dose-treated treated tenotomy rats was still lower than in the age-related controls. S-ketoprofen also prevented the increase in endocortical eroded perimeter induced by tenotomy. In summary, tenotomy inhibited age-related bone gain and stimulated bone loss in cancellous bone sites, and only inhibited age-related bone gain in cortical bone sites. S-ketoprofen treatment at the highest dose levels prevented the changes in cancellous bone, and reduced marrow area to increase cortical bone in the tibial shafts.

Spaceflight and the skeleton: lessons for the earthbound

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Halloran, B. P.; Morey-Holton, E.

1997-01-01

Loss of bone during extended space flight has long been a concern that could limit the ability of humans to explore the universe. Surprisingly the available data do not support the concept that weightlessness leads inexorably to a depleted skeleton unable to withstand the stress of a return to a 1g environment. Nevertheless, some bone loss does occur especially in those bones most stressed by gravity prior to flight, providing confirmation of the proposal formulated over a century ago by Julius Wolff that mechanical stress determines the form and function of bone. Although the phenomenon of bone loss with skeletal unloading, whether by space flight or immobilization or just taking a load off your feet (literally) is well established, the mechanisms by which bone senses load and adjusts to it are not so clear. What actually is the stimulus and what are the sensors? What are the target cells? How do the sensors communicate the message into the cells, and by what pathways do the cells respond? What is the role of endocrine factors versus paracrine or autocrine factors in mediating or modulating the response? None of these questions has been answered with certainty, but as will become apparent in this review, we have some clues directing us to the answers. Although the focus of this review concerns space flight, it seems highly likely that the mechanisms mediating the transmission of mechanical load to changes in bone formation and resorption apply equally well to all forms of disuse osteoporosis, and are likely to be the same mechanisms affected by other etiologies of osteoporosis.

Space flight and the skeleton: lessons for the earthbound

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Halloran, B. P.; Morey-Holton, E.

1997-01-01

Loss of bone during extended space flight has long been a concern that could limit the ability of humans to explore the universe. Surprisingly, the available data do not support the concept that weightlessness leads inexorably to a depleted skeleton unable to withstand the stress of a return to a 1-g environment. Nevertheless, some bone loss does occur, especially in those bones most stressed by gravity prior to flight, which provides confirmation of the proposal formulated over a century ago by Julius Wolff that mechanical stress determines the form and function of bone. Although the phenomenon of bone loss with skeletal unloading, whether by space flight or immobilization or just taking a load off your feet (literally) is well established, the mechanisms by which bone senses load and adjusts to it are not so clear. What actually is the stimulus, and what are the sensors? What are the target cells? How do the sensors communicate the message into the cells, and by what pathways do the cells respond? What is the role of endocrine, factors vs. paracrine or autocrine factors in mediating or modulating the response? None of these questions has been answered with certainty, but, as will become apparent in this review, we have some clues directing us to the answers. Although the focus of this review concerns space flight, it seems highly likely that the mechanisms mediating the transmission of mechanical load to changes in bone formation and resorption apply equally well to all forms of disuse osteoporosis and are likely to be the same mechanisms affected by other etiologies of osteoporosis.

Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice

PubMed Central

Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

2015-01-01

Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia. PMID:26664256

Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice.

PubMed

Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

2015-01-01

Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia.

Bisphosphonates as a Countermeasure to Space Flight Induced Bone Loss

NASA Technical Reports Server (NTRS)

LeBlanc, Adrian; Matsumoto, Toshio; Jones, Jeffrey A.; Shapiro, Jay; Lang, Thomas F.; Smith, Scott M.; Shackelford, Linda C.; Sibonga, Jean; Evans, Harlan; Spector, Elisabeth;

Anti-osteoporotic activity of harpagide by regulation of bone formation in osteoblast cell culture and ovariectomy-induced bone loss mouse models.

PubMed

Chung, Hwa-Jin; Kyung Kim, Won; Joo Park, Hyen; Cho, Lan; Kim, Me-Riong; Kim, Min Jeong; Shin, Joon-Shik; Ho Lee, Jin; Ha, In-Hyuk; Kook Lee, Sang

2016-02-17

Harpagide, an iridoid glucoside, is a constituent of the root of Harpagophytum procumbens var. sublobatum (Engl.) Stapf, Devil's claw which has been used in patients with osteoarthritis (OA). In the present study, we investigated the anti-osteoporotic potential of harpagide and its underlying mechanism of action in in vitro cell culture and in vivo bone loss animal models. Harpagide was obtained from the alkalic hydrolysis of harpagoside, a major constituent of H. procumbens var. sublobatum Analysis of biomarkers for bone formation in osteoblastic MC3T3-E1 cells and bone resorption in osteoclast cells derived from mouse bone marrow cells was performed to evaluate the mechanism of action. The protective activity of harpagide against bone loss was also evaluated in ovariectomized (OVX) mouse model. Harpagide improved bone properties by stimulating the process of differentiation and maturation of osteoblast cells and suppressing the process of RANKL-induced differentiation of osteoclast cells. In OVX-induced bone loss mouse model, oral administration of harpagide significantly improved recovery of bone mineral density, trabecular bone volume, and trabecular number in the femur. Harpagide also prevented increase of trabecular separation and structure model index induced by OVX. Harpagide effectively inhibited the serum levels of biochemical markers of bone loss, including alkaline phosphatase, osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase. Taken together, the present study demonstrates that harpagide has a potential for prevention of bone loss in OVX mice by regulating the stimulation of osteoblast differentiation and the suppression of osteoclast formation. Therefore, these findings suggest that harpagide might serve as a bioactive compound derived from H. procumbens var. sublobatum for improvement of age-dependent bone destruction disease. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Use of micro-computed tomography to evaluate the effects of exercise on preventing the degeneration of articular cartilage in tail-suspended rats

NASA Astrophysics Data System (ADS)

Luan, Hui-Qin; Sun, Lian-Wen; Huang, Yun-Fei; Wu, Xin-tong; Niu, Haijun; Liu, Hong; Fan, Yu-Bo

2015-07-01

Space flight has been shown to induce bone loss and muscle atrophy, which could initiate the degeneration of articular cartilage. Countermeasures to prevent bone loss and muscle atrophy have been explored, but few spaceflight or ground-based studies have focused on the effects on cartilage degeneration. In this study, we investigated the effects of exercise on articular cartilage deterioration in tail-suspended rats. Thirty-two female Sprague-Dawley rats were randomly divided into four groups (n = 8 in each): tail suspension (TS), tail suspension plus passive motion (TSP), tail suspension plus active exercise (TSA), and control (CON) groups. In the TS, TSP, and TSA groups, the rat hindlimbs were unloaded for 21 days by tail suspension. Next, the cartilage thickness and volume, and the attenuation coefficient of the distal femur were evaluated by micro-computed tomography (μCT). Histological analysis was used to assess the surface integrity of the cartilage, cartilage thickness, and chondrocytes. The results showed that: (1) the cartilage thickness on the distal femur was significantly lower in the TS and TSP groups compared with the CON and TSA groups; (2) the cartilage volume in the TS group was significantly lower compared with the CON, TSA, and TSP groups; and (3) histomorphology showed that the chondrocytes formed clusters where the degree of matrix staining was lower in the TS and TSP groups. There were no significant differences between any of these parameters in the CON and TSA groups. The cartilage thickness measurements obtained by μCT and histomorphology correlated well. In general, tail suspension could induce articular cartilage degeneration, but active exercise was effective in preventing this degeneration in tail-suspended rats.

Femoral Head Bone Loss Following Short and Long-Duration Spaceflight

NASA Technical Reports Server (NTRS)

Blaber, E. A.; Cheng-Campbell, M.; Almeida, E. A. C.

2016-01-01

Exposure to mechanical unloading during spaceflight is known to have significant effects on the musculoskeletal system. Our ongoing studies with the mouse bone model have identified the failure of normal stem cell-based tissue regeneration, in addition to tissue degeneration, as a significant concern for long-duration spaceflight, especially in the mesenchymal and hematopoietic tissue lineages. The 30-day BionM1 and the 37-day Rodent Research 1 (RR1) missions enabled the possibility of studying these effects in long-duration microgravity experiments. We hypothesized that the inhibition of stem cell-based tissue regeneration in short-duration spaceflight would continue during long-duration spaceflight and furthermore would result in significant tissue alterations. MicroCT analysis of BionM1 femurs revealed 31% decrease in bone volume ratio, a 14% decrease in trabecular thickness, and a 20% decrease in trabecular number in the femoral head of space-flown mice. Furthermore, high-resolution MicroCT and immunohistochemical analysis of spaceflight tissues revealed a severe disruption of the epiphyseal boundary, resulting in endochondral ossification of the femoral head and perforation of articular cartilage by bone. This suggests that spaceflight in microgravity may cause rapid induction of an aging-like phenotype with signs of osteoarthritic disease in the hip joint. However, mice from RR1 exhibited significant bone loss in the femoral head but did not exhibit the severe aging and disease-like phenotype observed during BionM1.This may be due to increased physical activity in the RH hardware. Immunohistochemical analysis of the epiphyseal plate and investigation of cellular proliferation and differentiation pathways within the marrow compartment and whole bone tissue is currently being conducted to determine alterations in stem cell-based tissue regeneration between these experiments. Our results show that the observed inhibition of stem cell-based tissue regeneration persists during long-duration spaceflight. Furthermore, spaceflight femurs from BionM1 indicate onset of an accelerated aging-like phenotype with signs of osteoarthritic disease shown by disruption of the epiphyseal boundary and endochondral ossification. These effects are likely caused by a failure of stem cells to regenerate degraded tissues and may have significant implications for bone and cartilage health following extensive periods of mechanical unloading during long-duration spaceflight.

Femoral Head Bone Loss Following Short and Long-Duration Spaceflight

NASA Technical Reports Server (NTRS)

Blaber, Elizabeth A.; Cheng-Campbell, Margareth A.; Almeida, Eduardo A. C.

2016-01-01

Exposure to mechanical unloading during spaceflight is known to have significant effects on the musculoskeletal system. Our ongoing studies with the mouse bone model have identified the failure of normal stem cell-based tissue regeneration, in addition to tissue degeneration, as a significant concern for long-duration spaceflight, especially in the mesenchymal and hematopoietic tissue lineages. The 30-day BionM1 and the 37-day Rodent Research 1 (RR1) missions enabled the possibility of studying these effects in long-duration microgravity experiments. We hypothesized that the inhibition of stem cell-based tissue regeneration in short-duration spaceflight would continue during long-duration spaceflight and furthermore would result in significant tissue alterations. MicroCT analysis of BionM1 femurs revealed 31 decrease in bone volume ratio, a 14 decrease in trabecular thickness, and a 20 decrease in trabecular number in the femoral head of space-flown mice. Furthermore, high-resolution MicroCT and immunohistochemical analysis of spaceflight tissues revealed a severe disruption of the epiphyseal boundary, resulting in endochondral ossification of the femoral head and perforation of articular cartilage by bone. This suggests that spaceflight in microgravity may cause rapid induction of an aging-like phenotype with signs of osteoarthritic disease in the hip joint. However, mice from RR1 exhibited significant bone loss in the femoral head but did not exhibit the severe aging and disease-like phenotype observed during BionM1. This may be due to increased physical activity in the RH hardware. Immunohistochemical analysis of the epiphyseal plate and investigation of cellular proliferation and differentiation pathways within the marrow compartment and whole bone tissue is currently being conducted to determine alterations in stem cell-based tissue regeneration between these experiments. Our results show that the observed inhibition of stem cell-based tissue regeneration persists during long-duration spaceflight. Furthermore, spaceflight femurs from BionM1 indicate onset of an accelerated aging-like phenotype with signs of osteoarthritic disease shown by disruption of the epiphyseal boundary and endochondral ossification. These effects are likely caused by a failure of stem cells to regenerate degraded tissues and may have significant implications for bone and cartilage health following extensive periods of mechanical unloading during long-duration spaceflight.

High Salt Intake Promotes Urinary Loss of Vitamin D Metabolites by Dahl Salt-Sensitive Rats in a Space Flight Model

NASA Technical Reports Server (NTRS)

Thierry-Palmer, M.; Cephas, S.; Sayavongsa, P.; Clark, T.; Arnaud, S. B.

2004-01-01

Vitamin D metabolism in the Dahl salt-sensitive (S) rat, a model of salt-induced hypertension, differs from that in the Dahl salt-resistant (R) rat. We have demonstrated that female S rats are more vulnerable than female R rats to decreases in plasma 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-(OH)2D) concentrations during hind limb unloading (a space flight model). We report here on the response of the vitamin D endocrine system of S and R rats to hind limb unloading during high salt intake. Dahl female rats (9.7-week-old) were tail-suspended (hind limb unloaded) for 28 days, while fed a diet containing twice the salt in standard rat chow (2 % sodium chloride). Control rats were fed the same diet, but were not hind limb unloaded. Vitamin D metabolites were analyzed by HPLC and radioimmunoassay kits from Diasorin.

Epigallocatechin gallate (EGCG) suppresses lipopolysaccharide-induced inflammatory bone resorption, and protects against alveolar bone loss in mice.

PubMed

Tominari, Tsukasa; Matsumoto, Chiho; Watanabe, Kenta; Hirata, Michiko; Grundler, Florian M W; Miyaura, Chisato; Inada, Masaki

2015-01-01

Epigallocatechin gallate (EGCG), a major polyphenol in green tea, possesses antioxidant properties and regulates various cell functions. Here, we examined the function of EGCG in inflammatory bone resorption. In calvarial organ cultures, lipopolysaccharide (LPS)-induced bone resorption was clearly suppressed by EGCG. In osteoblasts, EGCG suppressed the LPS-induced expression of COX-2 and mPGES-1 mRNAs, as well as prostaglandin E2 production, and also suppressed RANKL expression, which is essential for osteoclast differentiation. LPS-induced bone resorption of mandibular alveolar bones was attenuated by EGCG in vitro, and the loss of mouse alveolar bone mass was inhibited by the catechin in vivo.

Curcumin counteracts loss of force and atrophy of hindlimb unloaded rat soleus by hampering neuronal nitric oxide synthase untethering from sarcolemma

PubMed Central

Vitadello, Maurizio; Germinario, Elena; Ravara, Barbara; Libera, Luciano Dalla; Danieli-Betto, Daniela; Gorza, Luisa

2014-01-01

Antioxidant administration aimed to antagonize the development and progression of disuse muscle atrophy provided controversial results. Here we investigated the effects of curcumin, a vegetal polyphenol with pleiotropic biological activity, because of its ability to upregulate glucose-regulated protein 94 kDa (Grp94) expression in myogenic cells. Grp94 is a sarco-endoplasmic reticulum chaperone, the levels of which decrease significantly in unloaded muscle. Rats were injected intraperitoneally with curcumin and soleus muscle was analysed after 7 days of hindlimb unloading or standard caging. Curcumin administration increased Grp94 protein levels about twofold in muscles of ambulatory rats (P < 0.05) and antagonized its decrease in unloaded ones. Treatment countered loss of soleus mass and myofibre cross-sectional area by approximately 30% (P ≤ 0.02) and maintained a force–frequency relationship closer to ambulatory levels. Indexes of muscle protein and lipid oxidation, such as protein carbonylation, revealed by Oxyblot, and malondialdehyde, measured with HPLC, were significantly blunted in unloaded treated rats compared to untreated ones (P = 0.01). Mechanistic involvement of Grp94 was suggested by the disruption of curcumin-induced attenuation of myofibre atrophy after transfection with antisense grp94 cDNA and by the drug-positive effect on the maintenance of the subsarcolemmal localization of active neuronal nitric oxide synthase molecules, which were displaced to the sarcoplasm by unloading. The absence of additive effects after combined administration of a neuronal nitric oxide synthase inhibitor further supported curcumin interference with this pro-atrophic pathway. In conclusion, curcumin represents an effective and safe tool to upregulate Grp94 muscle levels and to maintain muscle function during unweighting. PMID:24710058

Voxel-based modeling and quantification of the proximal femur using inter-subject registration of quantitative CT images.

PubMed

Li, Wenjun; Kezele, Irina; Collins, D Louis; Zijdenbos, Alex; Keyak, Joyce; Kornak, John; Koyama, Alain; Saeed, Isra; Leblanc, Adrian; Harris, Tamara; Lu, Ying; Lang, Thomas

2007-11-01

We have developed a general framework which employs quantitative computed tomography (QCT) imaging and inter-subject image registration to model the three-dimensional structure of the hip, with the goal of quantifying changes in the spatial distribution of bone as it is affected by aging, drug treatment or mechanical unloading. We have adapted rigid and non-rigid inter-subject registration techniques to transform groups of hip QCT scans into a common reference space and to construct composite proximal femoral models. We have applied this technique to a longitudinal study of 16 astronauts who on average, incurred high losses of hip bone density during spaceflights of 4-6 months on the International Space Station (ISS). We compared the pre-flight and post-flight composite hip models, and observed the gradients of the bone loss distribution. We performed paired t-tests, on a voxel by voxel basis, corrected for multiple comparisons using false discovery rate (FDR), and observed regions inside the proximal femur that showed the most significant bone loss. To validate our registration algorithm, we selected the 16 pre-flight scans and manually marked 4 landmarks for each scan. After registration, the average distance between the mapped landmarks and the corresponding landmarks in the target scan was 2.56 mm. The average error due to manual landmark identification was 1.70 mm.

Sheep model for osteoporosis: The effects of peripheral hormone therapy on centrally induced systemic bone loss in an osteoporotic sheep model.

PubMed

Oheim, Ralf; Simon, Maciej J K; Steiner, Malte; Vettorazzi, Eik; Barvencik, Florian; Ignatius, Anita; Amling, Michael; Clarke, Iain J; Pogoda, Pia; Beil, F Timo

2017-04-01

Hypothalamic-pituitary disconnection (HPD) leads to low bone turnover followed by bone loss and reduced biomechanical properties in sheep. To investigate the role of peripheral hormones in this centrally induced systemic bone loss model, we planned a hormone replacement experiment. Therefore, estrogen (OHE), thyroxin (OHT) or a combination of both (OHTE) was substituted in ovariectomized HPD sheep, as both hormones are decreased in HPD sheep and are known to have a significant but yet not fully understood impact on bone metabolism. Bone turnover and structural parameters were analyzed in comparison to different control groups - untreated sheep (C), ovariectomized (O) and ovariectomized+HPD sheep (OH). We performed histomorphometric and HR-pQCT analyses nine months after the HPD procedure, as well as biomechanical testing of all ewes studied. In HPD sheep (OH) the low bone turnover led to a significant bone loss. Treatment with thyroxin alone (OHT) mainly increased bone resorption, leading to a further reduction in bone volume. In contrast, the treatment with estrogen alone (OHE) and the combined treatment with estrogen and thyroxin (OHTE) prevented HPD-induced bone loss completely. In conclusion, peripheral hormone substitution was able to prevent HPD-induced low-turnover osteoporosis in sheep. But only the treatment with estrogen alone or in combination with thyroxin was able to completely preserve bone mass and structure. These findings demonstrate the importance of peripheral hormones for a balanced bone remodeling and a physiological bone turnover. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genistein supplementation increases bone turnover but does not prevent alcohol-induced bone loss in male mice

USDA-ARS?s Scientific Manuscript database

Chronic alcohol consumption results in bone loss through increased bone resorption and decreased bone formation. These effects can be reversed by estradiol (E2) supplementation. Soy diets are suggested to have protective effects on bone loss in men and women, as a result of the presence of soy prote...

Gravity and Skeletal Growth

NASA Technical Reports Server (NTRS)

Morey-Holton, Emily; Turner, Russell T.

1999-01-01

Two simultaneous experiments were performed using 5-week-old male Sprague Dawley rats; in one study, the rats were flown in low earth orbit; in the other study, the hindlimbs of the growing rats were elevated to prevent weight bearing. Following 9 d of unloading, weight bearing was restored for 4, 28, and 76 hrs. Afterwards, additional hindlimb unloading experiments were performed to evaluate the skeletal response to 0, 2, 4, 6, 8, 10, 12, 16, and 24 hrs of restored weight bearing following 7 d of unloading. Cancellous and cortical bone histomorphometry were evaluated in the left tibia at the proximal metaphysis and in the left femur at mid-diaphysis, respectively. Steady-state mRNA levels for bone matrix proteins and skeletal signaling peptides were determined in total cellular RNA extracted from trabeculae from the right proximal tibiametaphysis and periosteum from the right femur. Spaceflight and hindlimb unloading each resulted in cancellous osteopenia, as well as a tendency towards decreased periosteal bone formation. Both models for skeletal unloading resulted in site specific reductions in mRNA levels for transforming growth factor-beta (sub 1) (TGF-beta) osteocalcin (OC), and prepro-alpha (I) subunit of type 1 collagen (collagen) and little or no changes in mRNA levels for glyceraldehyde-3-phosphate dehydrogenase (GAP) and insulin-like growth factor I (IGF-I). Restoration of normal weight bearing resulted in transient increases in mRNA levels for the bone matrix proteins and TGF-beta in the proximal metaphysis and periosteum and no changes in either GAP or IGF-I mRNA levels. The timecourse for the response differed between the two skeletal compartments; the tibial metaphysis responded much more quickly to reloading. These results suggest that the skeletal adaptation to acute physiological changes in mechanical usage are mediated, in part, by changes in mRNA levels for bone matrix proteins and TGF-beta.

Platinum nanoparticles reduce ovariectomy-induced bone loss by decreasing osteoclastogenesis

PubMed Central

Kim, Woon-Ki; Kim, Jin-Chun; Park, Hyun-Jung; Sul, Ok-Joo; Lee, Mi-Hyun; Kim, Ji-Soon

2012-01-01

Platinum nanoparticles (PtNP) exhibit remarkable antioxidant activity. There is growing evidence concerning a positive relationship between oxidative stress and bone loss, suggesting that PtNP could protect against bone loss by modulating oxidative stress. Intragastric administration of PtNP reduced ovariectomy (OVX)-induced bone loss with a decreased level of activity and number of osteoclast (OC) in vivo. PtNP inhibited OC formation by impairing the receptor activator of nuclear factor-κB ligand (RANKL) signaling. This impairment was due to a decreased activation of nuclear factor-κB and a reduced level of nuclear factor in activated T-cells, cytoplasmic 1 (NFAT2). PtNP lowered RANKL-induced long lasting reactive oxygen species as well as intracellular concentrations of Ca2+ oscillation. Our data clearly highlight the potential of PtNP for the amelioration of bone loss after estrogen deficiency by attenuated OC formation. PMID:22525805

Repression of Osteoblast Maturation by ERRα Accounts for Bone Loss Induced by Estrogen Deficiency

PubMed Central

Gallet, Marlène; Saïdi, Soraya; Haÿ, Eric; Photsavang, Johann; Marty, Caroline; Sailland, Juliette; Carnesecchi, Julie; Tribollet, Violaine; Barenton, Bruno; Forcet, Christelle; Birling, Marie-Christine; Sorg, Tania; Chassande, Olivier; Cohen-Solal, Martine; Vanacker, Jean-Marc

2013-01-01

ERRα is an orphan member of the nuclear receptor family, the complete inactivation of which confers resistance to bone loss induced by ageing and estrogen withdrawal to female mice in correlation with increased bone formation in vivo. Furthermore ERRα negatively regulates the commitment of mesenchymal cells to the osteoblast lineage ex vivo as well as later steps of osteoblast maturation. We searched to determine whether the activities of ERRα on osteoblast maturation are responsible for one or both types of in vivo induced bone loss. To this end we have generated conditional knock out mice in which the receptor is normally present during early osteoblast differentiation but inactivated upon osteoblast maturation. Bone ageing in these animals was similar to that observed for control animals. In contrast conditional ERRαKO mice were completely resistant to bone loss induced by ovariectomy. We conclude that the late (maturation), but not early (commitment), negative effects of ERRα on the osteoblast lineage contribute to the reduced bone mineral density observed upon estrogen deficiency. PMID:23359549

Effects of Imbalanced Muscle Loading on Hip Joint Development and Maturation

PubMed Central

Ford, Caleb A.; Nowlan, Niamh C.; Thomopoulos, Stavros; Killian, Megan L.

2017-01-01

The mechanical loading environment influences the development and maturation of joints. In this study, the influence of imbalanced muscular loading on joint development was studied using localized chemical denervation of hip stabilizing muscle groups in neonatal mice. It was hypothesized that imbalanced muscle loading, targeting either gluteal muscles or quadriceps muscles, would lead to bilateral hip joint asymmetry, as measured by acetabular coverage, femoral head volume and bone morphometry, and femoral-acetabular shape. The contralateral hip joints as well as age-matched, uninjected mice were used as controls. Altered bone development was analyzed using micro-computed tomography, histology, and image registration techniques at postnatal days (P) 28, 56, and 120. This study found that unilateral muscle unloading led to reduced acetabular coverage of the femoral head, lower total volume, lower bone volume ratio, and lower mineral density, at all three time points. Histologically, the femoral head was smaller in unloaded hips, with thinner triradiate cartilage at P28 and thinner cortical bone at P120 compared to contralateral hips. Morphological shape changes were evident in unloaded hips at P56. Unloaded hips had lower trabecular thickness and increased trabecular spacing of the femoral head compared to contralateral hips. The present study suggests that decreased muscle loading of the hip leads to altered bone and joint shape and growth during postnatal maturation. Statement of Clinical Significance: Adaptations from altered muscle loading during postnatal growth investigated in this study have implications on developmental hip disorders that result from asymmetric loading, such as patients with limb-length inequality or dysplasia. PMID:27391299

Prostaglandin E2 Prevents Bone Loss and Adds Extra Bone to Immobilized Distal Femoral Metaphysis in Female Rats

NASA Technical Reports Server (NTRS)

Akamine, T.; Jee, W. S. S.; Ke, H. Z.; Li, X. J.; Lin, B. Y.

1992-01-01

The object of this study was to determine whether prostaglandin E2 (PGE2) can prevent disuse (underloading)-induced cancellous bone loss. Thirteen-month-old retired female Sprague-Dawley breeders served as controls or were subjected to right hindlimb immobilization by bandaging and simultaneously treated subcutaneously daily with 0, 1, 3, or 6 mg PGE2/kg/d for two and six weeks. Histomorphometric analyses were performed on the cancellous bone using double-fluorescent labeled, 20 micron thick, undecalcified distal femoral metaphysis sections. We found that PGE2 administration not only prevented disuse-induced bone loss, but also added extra bone to disuse cancellous bone in a dose-response manner. PGE2 prevented the disuse-induced osteopenia by stimulating more bone formation than and shortening the period of bone remodeling. It activated woven bone formation, stimulated lamellar bone formation, and increased the eroded bone surface above that caused by disuse alone. While underloading increased the remodeling period (sigma), PGE2 treatment of underloaded bone shortened the time for osteoclastic bone resorption and bone remodeling, and thus reduced the remodeling space. The study shows that PGE2 is a powerful anabolic agent that prevents disuse-induced osteopenia and adds extra bone to these same bones.

FES-Rowing versus Zoledronic Acid to Improve BoneHealth in SCI

DTIC Science & Technology

2016-12-01

SUPPLEMENTARY NOTES 14. ABSTRACT There is no established treatment to prevent bone loss or to induce new bone formation following SCI, although the... no established treatment to prevent bone loss or to induce new bone formation following SCI. The goal of this clinical trial -- FES-Rowing versus...Army position, policy or decision unless so designated by other documentation. REPORT DOCUMENTATION PAGE Form Approved OMB No . 0704-0188 Public

Transplantation of Hepatocyte Growth Factor-Modified Dental Pulp Stem Cells Prevents Bone Loss in the Early Phase of Ovariectomy-Induced Osteoporosis.

PubMed

Kong, Fanxuan; Shi, Xuefeng; Xiao, Fengjun; Yang, Yuefeng; Zhang, Xiaoyan; Wang, Li-Sheng; Wu, Chu-Tse; Wang, Hua

2018-02-01

Investigations based on mesenchymal stem cells (MSCs) for osteoporosis have attracted attention recently. MSCs can be derived from various tissues, such as bone marrow, adipose, umbilical cord, placenta, and dental pulp. Among these, dental pulp-derived MSCs (DPSCs) and hepatocyte growth factor (HGF)-modified DPSCs (DPSCs-HGF) highly express osteogenic-related genes and have stronger osteogenic differentiation capacities. DPSCs have more benefits in treating osteoporosis. The purpose of this study was to investigate the roles of HGF gene-modified DPSCs in bone regeneration using a mouse model of ovariectomy (OVX)-induced bone loss. The HGF and luciferase genes were transferred into human DPSCs using recombinant adenovirus. These transduced cells were assayed for distribution or bone regeneration assay by transplantation into an OVX-induced osteoporosis model. By using bioluminogenic imaging, it was determined that some DPSCs could survive for >1 month in vivo. The DPSCs were mainly distributed to the lung in the early stage and to the liver in the late stage of OVX osteoporosis after administration, but they were scarcely distributed to the bone. The homing efficiency of DPSCs is higher when administrated in the early stage of a mouse OVX model. Micro-computed tomography indicated that DPSCs-Null or DPSCs-HGF transplantation significantly reduces OVX-induced bone loss in the trabecular bone of the distal femur metaphysis, and DPSCs-HGF show a stronger capacity to reduce bone loss. The data suggest that systemic infusion of DPSCs-HGF is a potential therapeutic approach for OVX-induced bone loss, which might be mediated by paracrine mechanisms.

The Effect of Spaceflight on Bone Cell Cultures

NASA Technical Reports Server (NTRS)

Landis, William J.

1999-01-01

Understanding the response of bone to mechanical loading (unloading) is extremely important in defining the means of adaptation of the body to a variety of environmental conditions such as during heightened physical activity or in extended explorations of space or the sea floor. The mechanisms of the adaptive response of bone are not well defined, but undoubtedly they involve changes occurring at the cellular level of bone structure. This proposal has intended to examine the hypothesis that the loading (unloading) response of bone is mediated by specific cells through modifications of their activity cytoskeletal elements, and/or elaboration of their extracellular matrices. For this purpose, this laboratory has utilized the results of a number of previous studies defining molecular biological, biochemical, morphological, and ultrastructural events of the reproducible mineralization of a primary bone cell (osteoblast) culture system under normal loading (1G gravity level). These data and the culture system then were examined following the use of the cultures in two NASA shuttle flights, STS-59 and STS-63. The cells collected from each of the flights were compared to respective synchronous ground (1G) control cells examined as the flight samples were simultaneously analyzed and to other control cells maintained at 1G until the time of shuttle launch, at which point they were terminated and studied (defined as basal cells). Each of the cell cultures was assayed in terms of metabolic markers- gene expression; synthesis and secretion of collagen and non-collagenous proteins, including certain cytoskeletal components; assembly of collagen into macrostructural arrays- formation of mineral; and interaction of collagen and mineral crystals during calcification of the cultures. The work has utilized a combination of biochemical techniques (radiolabeling, electrophoresis, fluorography, Western and Northern Blotting, and light microscopic immunofluorescence) and structural methods (conventional and high voltage electron microscopy, inununocytochemistry, stereomicroscopy, and 3D image reconstruction). The studies have provided new knowledge of aspects of bone cell development and structural regulation, extracellular matrix assembly, and mineralization during spaceflight and under normal gravity. The information has contributed to insights into the means in general by which cells respond and adapt to different conditions of gravity (loading). The data may as well have suggested an underlying basis for the observed loss of bone by vertebrates, including man, in microgravity; and these scientific results may have implications for understanding bone loss following fracture healing and extended periods of inactivity such as during long-term bedrest.

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

NASA Technical Reports Server (NTRS)

Globus, R. K.; Alwood, J.; Tahimic, C.; Schreurs, A.-S.; Shirazi-Fard, Y.; Terada, M.; Zaragoza, J.; Truong, T.; Bruns, K.; Castillo, A.;

Skeletal responses to spaceflight

NASA Technical Reports Server (NTRS)

Morey-Holton, Emily; Arnaud, Sara B.

1991-01-01

The role of gravity in the determination of bone structure is elucidated by observations in adult humans and juvenile animals during spaceflight. The primary response of bone tissue to microgravity is at the interface of the mineral and matrix in the process of biomineralization. This response is manifested by demineralization or retarded growth in some regions of the skeleton and hypermineralization in others. The most pronounced effects are seen in the heelbone and skull, the most distally located bones relative to the heart. Ground based flight simulation models that focus on changes in bone structure at the molecular, organ, and whole body levels are described and compared to flight results. On Earth, the morphologic and compositional changes in the unloaded bones are very similar to changes during flight; however, the ground based changes appear to be more transient. In addition, a redistribution of bone mineral in gravity-dependent bones occurs both in space and during head down positioning on Earth. Longitudinal data provided considerable information on the influence of endocrine and muscular changes on bone structure after unloading.

The influence of antiorthostatic unloading and long gamma-irradiation on rat bone marrow (MSCs)

NASA Astrophysics Data System (ADS)

Roe, Maria; Bobyleva, Polina; Shtemberg, Andrey; Buravkova, Ludmila

With the prospect of long interplanetary spaceflight becoming a real possibility there are some important questions that need to be answered regarding the combined effects of microgravity and long gamma-irradiation.The aim of this study was to evaluate the effects of synchronous antiorthostatic unloading and fractional gamma-irradiation on the functional characteristics of rat bone marrow multipotent stromal cells (MSCs).This experiment was carried out following all rules laid out by the Commission on Bioethics at the SSC RF - IBMP RAS. In this experiment the Wistar rats were kept in an unloaded position for a duration of 30 days. They were also subjected to 6 doses of gamma-radiation on the “GOBO-60” with a source of (137) Cs. The dose rate set to 1 meter 50 sGr / H (Total dose of 3 Gr).The study revealed a significant reduction in the number of colonies (CFU-F) in all cultures from the experimental groups when compared to the control groups. The most significant reduction was observed in the group, which had been subject to combined unloading, and radiation. This result was confirmed by examination of cell cultures during 10 days of growth.We found that the CD45 expression was increased in the groups exposed to radiation. At the same time a reduction in the expression of CD90 was observed during combination of radiation and unloading we found.The experimental groups also differed from the control group showing smaller lipid inclusions and decreased expression of alkaline phosphates in the MSCs. This experiment concluded that the bone marrow MSCs after a combination of unloading and multiple radiation sessions, showed a decrease in proliferation and differentiation potential which could reduce the adaption and reparative capacity of the organism.

Low rate loading-induced convection enhances net transport into the intervertebral disc in vivo.

PubMed

Gullbrand, Sarah E; Peterson, Joshua; Mastropolo, Rosemarie; Roberts, Timothy T; Lawrence, James P; Glennon, Joseph C; DiRisio, Darryl J; Ledet, Eric H

2015-05-01

The intervertebral disc primarily relies on trans-endplate diffusion for the uptake of nutrients and the clearance of byproducts. In degenerative discs, diffusion is often diminished by endplate sclerosis and reduced proteoglycan content. Mechanical loading-induced convection has the potential to augment diffusion and enhance net transport into the disc. The ability of convection to augment disc transport is controversial and has not been demonstrated in vivo. To determine if loading-induced convection can enhance small molecule transport into the intervertebral disc in vivo. Net transport was quantified via postcontrast enhanced magnetic resonance imaging (MRI) into the discs of the New Zealand white rabbit lumbar spine subjected to in vivo cyclic low rate loading. Animals were administered the MRI contrast agent gadodiamide intravenously and subjected to in vivo low rate loading (0.5 Hz, 200 N) via a custom external loading apparatus for either 2.5, 5, 10, 15, or 20 minutes. Animals were then euthanized and the lumbar spines imaged using postcontrast enhanced MRI. The T1 constants in the nucleus, annulus, and cartilage endplates were quantified as a measure of gadodiamide transport into the loaded discs compared with the adjacent unloaded discs. Microcomputed tomography was used to quantify subchondral bone density. Low rate loading caused the rapid uptake and clearance of gadodiamide in the nucleus compared with unloaded discs, which exhibited a slower rate of uptake. Relative to unloaded discs, low rate loading caused a maximum increase in transport into the nucleus of 16.8% after 5 minutes of loading. Low rate loading increased the concentration of gadodiamide in the cartilage endplates at each time point compared with unloaded levels. Results from this study indicate that forced convection accelerated small molecule uptake and clearance in the disc induced by low rate mechanical loading. Low rate loading may, therefore, be therapeutic to the disc as it may enhance the nutrient uptake and waste product clearance. Copyright © 2015 Elsevier Inc. All rights reserved.

Astronaut Bones: Stable Calcium Isotopes in Urine as a Biomarker of Bone Mineral Balance

NASA Astrophysics Data System (ADS)

Skulan, J.; Gordon, G. W.; Romaniello, S. J.; Anbar, A. D.; Smith, S. M.; Zwart, S.

2016-12-01

Bone loss is a common health concern, in conditions ranging from osteoporosis to cancer. Bone loss due to unloading is also an important health issue for astronauts. We demonstrate stable calcium isotopes, a tool developed in geochemistry, are capable of detecting real-time quantitative changes in net bone mineral balance (BMB) using serum and urine [1]. We validated this technique by comparing with DEXA and biomarker data in subjects during bed rest, a ground-based analog of space flight effects [2-4]. We now apply this tool to assess changes in astronauts' BMB before, during and after 4-6 month space missions. There is stable isotope fractionation asymmetry between bone formation and resorption. During bone formation there is a mass-dependent preference for "lighter" calcium isotopes to be removed from serum and incorporated into bone mineral. During bone resorption, there is no measurable isotopic discrimination between serum and bone. Hence, when bone formation rates exceed that of resorption, serum and urine become isotopically "heavy" due to the sequestration of "light" calcium in bone. Conversely, when bone resorption exceeds bone formation, serum and urine become isotopically "light" due to the release of the sequestered light calcium from bone. We measured Ca isotopes in urine of thirty International Space Station astronauts. Average Ca isotope values in astronauts' urine shift isotopically lighter during microgravity, consistent with negative net BMB. Within a month of return to Earth, astronauts returned to within error of their δ44Ca value prior to departure. Urine samples from astronauts testing bone loss countermeasures showed bisphosphonates provide a viable pharmacological countermeasure. Some, but not all, individuals appear able to resist bone loss through diet and intensive resistive exercise alone. This is a promising new technique for monitoring BMB in astronauts, and hopefully someday on the way to/from Mars, this also has important clinical applications for human health and terrestrial medicine [5]. REFERENCES [1] Morgan, J.L. et al (2011) Anal Chem 83, 6956-6962. [2] Skulan, J.L. et al. (2007) Clin Chem 53, 1155-1158. [3] Morgan, J.L. et al (2012) PNAS 109, 9989-9994. [4] Channon, M.B. et al (2015) Bone 77, 69-74. [5] Gordon, G.W. et al (2014) Leukemia 28, 2112-2115.

Novel Radiomitigator for Radiation-Induced Bone Loss

NASA Technical Reports Server (NTRS)

Schreurs, A-S; Shirazi-fard, Y.; Terada, M.; Alwood, J. S.; Steczina, S.; Medina, C.; Tahimic, C. G. T.; Globus, R. K.

2016-01-01

Radiation-induced bone loss can occur with radiotherapy patients, accidental radiation exposure and during long-term spaceflight. Bone loss due to radiation is due to an early increase in oxidative stress, inflammation and bone resorption, resulting in an imbalance in bone remodeling. Furthermore, exposure to high-Linear Energy Transfer (LET) radiation will impair the bone forming progenitors and reduce bone formation. Radiation can be classified as high-LET or low-LET based on the amount of energy released. Dried Plum (DP) diet prevents bone loss in mice exposed to total body irradiation with both low-LET and high-LET radiation. DP prevents the early radiation-induced bone resorption, but furthermore, we show that DP protects the bone forming osteoblast progenitors from high-LET radiation. These results provide insight that DP re-balances the bone remodeling by preventing resorption and protecting the bone formation capacity. This data is important considering that most of the current osteoporosis treatments only block the bone resorption but do not protect bone formation. In addition, DP seems to act on both the oxidative stress and inflammation pathways. Finally, we have preliminary data showing the potential of DP to be radio-protective at a systemic effect and could possible protect other tissues at risk of total body-irradiation such as skin, brain and heart.

Suppression of NADPH oxidases prevents chronic ethanol-induced bone loss

USDA-ARS?s Scientific Manuscript database

Since the molecular mechanisms through which chronic excessive alcohol consumption induces osteopenia and osteoporosis are largely unknown, potential treatments for prevention of alcohol-induced bone loss remain unclear. We have previously demonstrated that, chronic ethanol (EtOH) treatment leads to...

Partial Reductions in Mechanical Loading Yield Proportional Changes in Bone Density, Bone Architecture, and Muscle Mass

PubMed Central

Ellman, Rachel; Spatz, Jordan; Cloutier, Alison; Palme, Rupert; Christiansen, Blaine A; Bouxsein, Mary L

2014-01-01

Although the musculoskeletal system is known to be sensitive to changes in its mechanical environment, the relationship between functional adaptation and below-normal mechanical stimuli is not well defined. We investigated bone and muscle adaptation to a range of reduced loading using the partial weight suspension (PWS) system, in which a two-point harness is used to offload a tunable amount of body weight while maintaining quadrupedal locomotion. Skeletally mature female C57Bl/6 mice were exposed to partial weight bearing at 20%, 40%, 70%, or 100% of body weight for 21 days. A hindlimb unloaded (HLU) group was included for comparison in addition to age-matched controls in normal housing. Gait kinematics was measured across the full range of weight bearing, and some minor alterations in gait from PWS were identified. With PWS, bone and muscle changes were generally proportional to the degree of unloading. Specifically, total body and hindlimb bone mineral density, calf muscle mass, trabecular bone volume of the distal femur, and cortical area of the femur midshaft were all linearly related to the degree of unloading. Even a load reduction to 70% of normal weight bearing was associated with significant bone deterioration and muscle atrophy. Weight bearing at 20% did not lead to better bone outcomes than HLU despite less muscle atrophy and presumably greater mechanical stimulus, requiring further investigation. These data confirm that the PWS model is highly effective in applying controllable, reduced, long-term loading that produces predictable, discrete adaptive changes in muscle and bone of the hindlimb. PMID:23165526

Inhibitory effects of Persicariae Rhizoma aqueous extracts on experimental periodontitis and alveolar bone loss in Sprague-Dawley rats

PubMed Central

Kang, Su Jin; Lee, Eun Kyung; Han, Chang Hyun; Lee, Bong Hyo; Lee, Young Joon; Ku, Sae Kwang

2016-01-01

Persicariae Rhizoma (PR) is the dried stem parts of Persicaria tinctoria H. Gross (Polygonaceae), and has been traditionally used as anti-inflammatory and detoxifying agent. In the present study, the effects of PR aqueous extracts on ligation-induced experimental periodontitis (EPD) and associated alveolar bone loss in rats were examined. Following the induction of EPD in rats, PR extracts were orally administered once a day for 10 days, and the changes and gains in body weight, alveolar bone loss and total aerobic bacterial counts of buccal gingiva were observed with histopathological analysis. In addition, anti-inflammatory effects were evaluated by monitoring myeloperoxidase (MPO) activities, and interleukin (IL)-1β and tumor necrosis factor (TNF)-α contents, and anti-oxidant effects were investigated by measuring inducible nitric oxide synthase (iNOS) activities and malondialdehyde (MDA) levels. Bacterial proliferation, periodontitis and associated alveolar bone loss induced by ligature placement were significantly and dose-dependently inhibited by the treatment with PR extracts. The inhibitory effects of 200 mg/kg PR were similar to those of 5 mg/kg indomethacin on ligation-induced periodontitis and associated alveolar bone losses in this study. The results suggest that PR effectively inhibits ligature placement-induced periodontitis and alveolar bone loss in rats via antibacterial, antioxidative and anti-inflammatory activities. PMID:27588077

Effects of Cinnamoyloxy-mammeisin from Geopropolis on Osteoclast Differentiation and Porphyromonas gingivalis-Induced Periodontitis.

PubMed

da Cunha, Marcos Guilherme; Ramos-Junior, Erivan Schnaider; Franchin, Marcelo; Taira, Thaise Mayumi; Beutler, John A; Franco, Gilson Cesar Nobre; Ikegaki, Masaharu; de Alencar, Severino Matias; Fukada, Sandra Yasuyo; Rosalen, Pedro Luiz

2017-06-23

Bone-loss-related diseases such as rheumatoid arthritis, osteomyelitis, osteoporosis, and periodontitis are associated with high rates of morbidity worldwide. These disorders are characterized by an imbalance between the formation and activity of osteoblasts and osteoclasts, leading to bone loss. In this context, we evaluated the effect of cinnamoyloxy-mammeisin (CNM), an anti-inflammatory coumarin found in Melipona scutellaris geopropolis, on key targets related to bone remodeling. In the present study we investigated the in vitro effects of CNM on osteoclast differentiation and M-CSF+RANKL-induced osteoclastogenic marker expression. Additionally, the interference of CNM treatment on osteoclast activity was evaluated by zymography and resorption area. Finally, we assessed the capacity of the compound to mitigate alveolar bone loss in vivo in experimental murine periodontitis induced by Porphyromonas gingivalis. We observed that treatment with CNM impaired osteoclast differentiation, as evidenced by a reduced number of tartrate-resistant acid-phosphatase-positive multinucleated cells (TRAP+) as well as the expression of osteoclastogenic markers upon M-CSF+RANKL-induced stimulation. Similarly, we observed reduced gelatinolytic and resorption capacity in M-CSF+RANKL-induced cells in vitro. Lastly, CNM attenuated alveolar bone loss in an experimental murine periodontitis model. These findings indicate that CNM may be considered a promising treatment for bone loss diseases.

Decursin from Angelica gigas suppresses RANKL-induced osteoclast formation and bone loss.

PubMed

Wang, Xin; Zheng, Ting; Kang, Ju-Hee; Li, Hua; Cho, Hyewon; Jeon, Raok; Ryu, Jae-Ha; Yim, Mijung

2016-03-05

Osteoclasts are the only cells capable of breaking down bone matrix, and excessive activation of osteoclasts is responsible for bone-destructive diseases. In this study, we investigated the effects of decursin from extract of Angelica gigas root on receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclast formation using mouse bone marrow-derived macrophages (BMMs). Decursin inhibited RANKL-induced osteoclast formation without cytotoxicity. In particular, decursin maintains the characteristics of macrophages by blocking osteoclast differentiation by RANKL. Furthermore, the RANKL-stimulated bone resorption was diminished by decursin. Mechanistically, decursin blocked the RANKL-triggered ERK mitogen-activated protein kinases (MAPK) phosphorylation, which results in suppression of c-Fos and the nuclear factor of activated T cells (NFATc1) expression. In accordance with the in vitro study, decursin reduced lipopolysaccharide (LPS)- or ovariectomy (OVX)-induced bone loss in vivo. Therefore, decursin exerted an inhibitory effect on osteoclast formation and bone loss in vitro and in vivo. Decursin could be useful for the treatment of bone diseases associated with excessive bone resorption. Copyright © 2016 Elsevier B.V. All rights reserved.

A cannabinoid 2 receptor agonist attenuates bone cancer-induced pain and bone loss

PubMed Central

Lozano, Alysia; Wright, Courtney; Vardanyan, Anna; King, Tamara; Largent-Milnes, Tally M.; Nelson, Mark; Jimenez-Andrade, Juan Miguel; Mantyh, Patrick W; Vanderah, Todd W.

2010-01-01

Aims Cannabinoid CB2 agonists have been shown to alleviate behavioral signs of inflammatory and neuropathic pain in animal models. AM1241, a CB2 agonist, does not demonstrate central nervous system side-effects seen with CB1 agonists such as hypothermia and catalepsy. Metastatic bone cancer causes severe pain in patients and is treated with analgesics such as opiates. Recent reports suggest that sustained opiates can produce paradoxical hyperalgesic actions and enhance bone destruction in a murine model of bone cancer. In contrast, CB2 selective agonists have been shown to reduce bone loss associated with a model of osteoporosis. Here we tested whether a CB2 agonist administered over a 7 day period inhibits bone cancer-induced pain as well as attenuates cancer-induced bone degradation. Main Methods A murine bone cancer model was used in which osteolytic sarcoma cells were injected into the intramedullary space of the distal end of the femur. Behavioral and radiographic image analysis was performed at days 7, 10 and 14 after injection of tumor cells into the femur. Key Findings Osteolytic sarcoma within the femur produced spontaneous and touch evoked behavioral signs of pain within the tumor-bearing limb. The systemic administration of AM1241 acutely or for 7 days significantly attenuated spontaneous and evoked pain in the inoculated limb. Sustained AM1241 significantly reduced bone loss and decreased the incidence of cancer-induced bone fractures. Significance These findings suggest a novel therapy for cancer-induced bone pain, bone loss and bone fracture while lacking many unwanted side effects seen with current treatments for bone cancer pain. PMID:20176037

Passive stretch reduces calpain activity through nitric oxide pathway in unloaded soleus muscles.

PubMed

Xu, Peng-Tao; Li, Quan; Sheng, Juan-Juan; Chang, Hui; Song, Zhen; Yu, Zhi-Bin

2012-08-01

Unloading in spaceflight or long-term bed rest induces to pronounced atrophy of anti-gravity skeletal muscles. Passive stretch partially resists unloading-induced atrophy of skeletal muscle, but the mechanism remains elusive. The aims of this study were to investigate the hypotheses that stretch tension might increase protein level of neuronal nitric oxide synthase (nNOS) in unloaded skeletal muscle, and then nNOS-derived NO alleviated atrophy of skeletal muscle by inhibiting calpain activity. The tail-suspended rats were used to unload rat hindlimbs for 2 weeks, at the same time, left soleus muscle was stretched by applying a plaster cast to fix the ankle at 35° dorsiflexion. Stretch partially resisted atrophy and inhibited the decreased protein level and activity of nNOS in unloaded soleus muscles. Unloading increased frequency of calcium sparks and elevated intracellular resting and caffeine-induced Ca(2+) concentration ([Ca(2+)]i) in unloaded soleus muscle fibers. Stretch reduced frequency of calcium sparks and restored intracellular resting and caffeine-induced Ca(2+) concentration to control levels in unloaded soleus muscle fibers. The increased protein level and activity of calpain as well as the higher degradation of desmin induced by unloading were inhibited by stretch in soleus muscles. In conclusion, these results suggest that stretch can preserve the stability of sarcoplasmic reticulum Ca(2+) release channels which prevents the elevated [Ca(2+)]i by means of keeping nNOS activity, and then the enhanced protein level and activity of calpain return to control levels in unloaded soleus muscles. Therefore, stretch can resist in part atrophy of unloaded soleus muscles.

Animal Models of Bone Loss in Inflammatory Arthritis: from Cytokines in the Bench to Novel Treatments for Bone Loss in the Bedside-a Comprehensive Review.

PubMed

Alves, C Henrique; Farrell, Eric; Vis, Marijn; Colin, Edgar M; Lubberts, Erik

2016-08-01

Throughout life, bone is continuously remodelled. Bone is formed by osteoblasts, from mesenchymal origin, while osteoclasts induce bone resorption. This process is tightly regulated. During inflammation, several growth factors and cytokines are increased inducing osteoclast differentiation and activation, and chronic inflammation is a condition that initiates systemic bone loss. Rheumatoid arthritis (RA) is a chronic inflammatory auto-immune disease that is characterised by active synovitis and is associated with early peri-articular bone loss. Peri-articular bone loss precedes focal bone erosions, which may progress to bone destruction and disability. The incidence of generalised osteoporosis is associated with the severity of arthritis in RA and increased osteoporotic vertebral and hip fracture risk. In this review, we will give an overview of different animal models of inflammatory arthritis related to RA with focus on bone erosion and involvement of pro-inflammatory cytokines. In addition, a humanised endochondral ossification model will be discussed, which can be used in a translational approach to answer osteoimmunological questions.

Temporal changes in sarcomere lesions of rat adductor longus muscles during hindlimb reloading

NASA Technical Reports Server (NTRS)

Krippendorf, B. B.; Riley, D. A.

1994-01-01

Focal sarcomere disruptions were previously observed in adductor longus muscles of rats flown approximately two weeks aboard the Cosmos 1887 and 2044 biosatellite flights. These lesions, characterized by breakage and loss of myofilaments and Z-line streaming, resembled damage induced by unaccustomed exercise that includes eccentric contractions in which muscles lengthen as they develop tension. We hypothesized that sarcomere lesions in atrophied muscles of space flow rats were not produced in microgravity by muscle unloading but resulted from muscle reloading upon re-exposure to terrestrial gravity. To test this hypothesis, we examined temporal changes in sarcomere integrity of adductor longus muscles from rats subjected to 12.5 days of hindlimb suspension unloading and subsequent reloading by return to vivarium cages for 0, 6, 12, or 48 hours of normal weightbearing. Our ultrastructural observations suggested that muscle unloading (0 h reloading) induced myofibril misalignment associated with myofiber atrophy. Muscle reloading for 6 hours induced focal sarcomere lesions in which cross striations were abnormally widened. Such lesions were electron lucent due to extensive myofilament loss. Lesions in reloaded muscles showed rapid restructuring. By 12 hours of reloading, lesions were moderately stained foci and by 48 hours darkly stained foci in which the pattern of cross striations was indistinct at the light and electron microscopic levels. These lesions were spanned by Z-line-like electron dense filamentous material. Our findings suggest a new role for Z-line streaming in lesion restructuring: rather than an antecedent to damage, this type of Z-line streaming may be indicative of rapid, early sarcomere repair.

Bisphosphonates as a Countermeasure to Space Flight Induced Bone Loss

NASA Technical Reports Server (NTRS)

LeBlanc, A.; Matsumoto, T.; Jones, J.; Shapiro, J.; Lang, T.; Shackelford, L.; Smith, S.; Evans, H.; Spector, E.; Ploutz-Snyder, R.;

Estrogen prevents bone loss through transforming growth factor β signaling in T cells

PubMed Central

Gao, Yuhao; Qian, Wei-Ping; Dark, Kimberly; Toraldo, Gianluca; Lin, Angela S. P.; Guldberg, Robert E.; Flavell, Richard A.; Weitzmann, M. Neale; Pacifici, Roberto

2004-01-01

Estrogen (E) deficiency leads to an expansion of the pool of tumor necrosis factor (TNF)-producing T cells through an IFN-γ-dependent pathway that results in increased levels of the osteoclastogenic cytokine TNF in the bone marrow. Disregulated IFN-γ production is instrumental for the bone loss induced by ovariectomy (ovx), but the responsible mechanism is unknown. We now show that mice with T cell-specific blockade of type β transforming growth factor (TGFβ) signaling are completely insensitive to the bone-sparing effect of E. This phenotype results from a failure of E to repress IFN-γ production, which, in turn, leads to increased T cell activation and T cell TNF production. Furthermore, ovx blunts TGFβ levels in the bone marrow, and overexpression of TGFβ in vivo prevents ovx-induced bone loss. These findings demonstrate that E prevents bone loss through a TGFβ-dependent mechanism, and that TGFβ signaling in T cells preserves bone homeostasis by blunting T cell activation. Thus, stimulation of TGFβ production in the bone marrow is a critical “upstream” mechanism by which E prevents bone loss, and enhancement of TGFβ levels in vivo may constitute a previously undescribed therapeutic approach for preventing bone loss. PMID:15531637

Altered cellular kinetics in growth plate according to alterations in weight bearing.

PubMed

Park, Hoon; Kong, Sun Young; Kim, Hyun Woo; Yang, Ick Hwan

2012-05-01

To examine the effects of change in weight bearing on the growth plate metabolism, a simulated animal model of weightlessness was introduced and the chondrocytes' cellular kinetics was evaluated. Unloading condition on the hind-limb of Sprague-Dawley rats was created by fixing a tail and lifting the hind-limb. Six rats aged 6 weeks old were assigned to each group of unloading, reloading, and control groups of unloading or reloading. Unloading was maintained for three weeks, and then reloading was applied for another one week thereafter. Histomorphometry for the assessment of vertical length of the growth plate, 5-bromo-2'-deoxyuridin immunohistochemistry for cellular kinetics, and biotin nick end labeling transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay for chondrocytes apoptosis in the growth plate were performed. The vertical length of the growth plate and the proliferative potential of chondrocytes were decreased in the unloading group compared to those of control groups. Inter-group differences were more significant in the proliferative and hypertrophic zones. Reloading increased the length of growth plate and proliferative potential of chondrocytes. However, apoptotic changes in the growth plate were not affected by the alterations of weight bearing. Alterations in the weight bearing induced changes in the chondrocytic proliferative potential of the growth plate, however, had no effects on the apoptosis. This may explain why non-weight bearing in various clinical situations hampers normal longitudinal bone growth. Further studies on the factors for reversibility of chondrocytic proliferation upon variable mechanical stresses are needed.

Synergistic Effect of Green Tea Polyphenols and Vitamin D on Chronic Inflammation-Induced Bone Loss in Female Rats

USDA-ARS?s Scientific Manuscript database

Our recent study demonstrated a bone-protective role of green tea polyphenols (GTPs), extracted from green tea, in chronic inflammation-induced bone loss of female rats through reduction of inflammation and oxidative stress. This study further examines effects of GTPs in conjunction with vitamin D (...

Yeast-incorporated gallium attenuates glucocorticoid-induced bone loss in rats by inhibition of bone resorption.

PubMed

Ren, Zhaozhou; Yang, Liqing; Xue, Feng; Meng, Qingjie; Wang, Kejia; Wu, Xian; Ji, Chao; Jiang, Teng; Liu, Da; Zhou, Long; Zhang, Jing; Fu, Qin

2013-06-01

Glucocorticoids (GC) are potent anti-inflammatory agents and widely used for the treatment of many immune-mediated and inflammatory diseases, whereas GC-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis and significantly increases the patients' morbidity and mortality. GIOP is characterized as diminished osteogenesis and accelerated bone resorption. Yeast-incorporated gallium (YG) as an organic compound not only reduces elements-associated toxicity, but also maintains its therapeutic effect on improving bone loss or promoting fracture healing in ovariectomized female rats. The aim of this study was to examine whether YG could prevent GC-induced bone loss. Five-month-old male Sprague-Dawley rats were randomly divided into three groups (n = 6): two groups were administered dexamethasone (0.1 mg/kg/day) or vehicle (PBS) subcutaneously for 5 weeks; one other group was received dexamethasone subcutaneously and YG (120 μg/kg/day) orally. Trabecular bone microarchitectural parameters, bone mineral density (BMD), bone strength, body weight, and serum biochemical markers of bone resorption and formation were examined. Compared to the GC alone group, treatment with YG not only prevented microarchitectural deterioration of trabecular bone volume relative to tissue volume, trabecular number, and trabecular separation, but also significantly improved BMD, mechanical strength, and body weight in GC-treated rats. Moreover, YG decreased tartrate-resistant acid phosphatase 5b level but failed to change alkaline phosphatase level in GC-treated rats. This is the first study to show that YG prominently attenuates bone loss and microarchitectural deterioration and inhibits the increased bone resorption in GIOP. It implies that YG might be an alternative therapy for prevention of GC-induced bone loss in humans.

NADPH oxidase 4 limits bone mass by promoting osteoclastogenesis

PubMed Central

Goettsch, Claudia; Babelova, Andrea; Trummer, Olivia; Erben, Reinhold G.; Rauner, Martina; Rammelt, Stefan; Weissmann, Norbert; Weinberger, Valeska; Benkhoff, Sebastian; Kampschulte, Marian; Obermayer-Pietsch, Barbara; Hofbauer, Lorenz C.; Brandes, Ralf P.; Schröder, Katrin

2013-01-01

ROS are implicated in bone diseases. NADPH oxidase 4 (NOX4), a constitutively active enzymatic source of ROS, may contribute to the development of such disorders. Therefore, we studied the role of NOX4 in bone homeostasis. Nox4–/– mice displayed higher bone density and reduced numbers and markers of osteoclasts. Ex vivo, differentiation of monocytes into osteoclasts with RANKL and M-CSF induced Nox4 expression. Loss of NOX4 activity attenuated osteoclastogenesis, which was accompanied by impaired activation of RANKL-induced NFATc1 and c-JUN. In an in vivo model of murine ovariectomy–induced osteoporosis, pharmacological inhibition or acute genetic knockdown of Nox4 mitigated loss of trabecular bone. Human bone obtained from patients with increased osteoclast activity exhibited increased NOX4 expression. Moreover, a SNP of NOX4 was associated with elevated circulating markers of bone turnover and reduced bone density in women. Thus, NOX4 is involved in bone loss and represents a potential therapeutic target for the treatment of osteoporosis. PMID:24216508

Inhibitory effects of melatonin on titanium particle-induced inflammatory bone resorption and osteoclastogenesis via suppression of NF-κB signaling.

PubMed

Ping, Zichuan; Wang, Zhirong; Shi, Jiawei; Wang, Liangliang; Guo, Xiaobin; Zhou, Wei; Hu, Xuanyang; Wu, Xiexing; Liu, Yu; Zhang, Wen; Yang, Huilin; Xu, Yaozeng; Gu, Ye; Geng, Dechun

2017-10-15

Wear debris-induced peri-implant osteolysis challenges the longevity of implants. The host response to wear debris causes chronic inflammation, promotes bone resorption, and impairs bone formation. We previously demonstrated that melatonin enhances bone formation and attenuates wear debris-induced bone loss in vivo. However, whether melatonin inhibits chronic inflammation and bone resorption at sites of wear debris-induced osteolysis remains unclear. In this study, we examined the potential inhibitory effects of melatonin on titanium particle-induced inflammatory osteolysis in a murine calvarial model and on RANKL-induced osteoclastic formation in bone marrow-derived macrophages. We found that the exogenous administration of melatonin significantly inhibited wear debris-induced bone resorption and the expression of inflammatory cytokines in vivo. Additionally, melatonin inhibited RANKL-induced osteoclast differentiation, F-actin ring formation, and osteoclastic resorption in a concentration-dependent manner in vitro. We also showed that melatonin blocked the phosphorylation of IκB-α and p65, but not IKKα, and significantly inhibited the expression of NFATc1 and c-Fos. However, melatonin had no effect on MAPK or PI3K/AKT signaling pathways. These results provide novel mechanistic insight into the anti-inflammatory and anti-bone resorptive effects of melatonin on wear debris-induced bone loss and provide an evidence-based rationale for the protective effects of melatonin as a treatment for peri-implant osteolysis. Wear debris-induced chronic inflammation, osteoclastic activation and osteoblastic inhibition have been identified as critical factors of peri-implant bone loss. We previously demonstrated that melatonin, a bioactive indolamine secreted mainly by the pineal gland, activates Wnt/β-catenin signaling pathway and enhances bone regeneration at osteolytic site in vivo. In the current study, we further demonstrated that melatonin significantly suppresses wear debris-induced bone resorption and inflammatory cytokine expression in vivo. In addition, melatonin inhibits receptor activator of nuclear factor kappa-B ligand induced osteoclast formation and osteoclastic bone resorption in vitro. Meanwhile, we found that melatonin mediates its anti-inflammation and anti-bone resorption effects by abrogating nuclear factor kappa-B activation. These results further support the protective effects of melatonin on wear debris-induced peri-implant bone loss, and strongly suggest that melatonin could be considered as a potential candidate for the prevention and treatment of wear debris-induced osteolysis and subsequent aseptic loosening. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zoledronate prevents lactation induced bone loss and results in additional post-lactation bone mass in mice.

PubMed

Wendelboe, Mette Høegh; Thomsen, Jesper Skovhus; Henriksen, Kim; Vegger, Jens Bay; Brüel, Annemarie

2016-06-01

In rodents, lactation is associated with a considerable and very rapid bone loss, which almost completely recovers after weaning. The aim of the present study was to investigate whether the bisphosphonate Zoledronate (Zln) can inhibit lactation induced bone loss, and if Zln interferes with recovery of bone mass after lactation has ceased. Seventy-six 10-weeks-old NMRI mice were divided into the following groups: Baseline, Pregnant, Lactation, Lactation+Zln, Recovery, Recovery+Zln, and Virgin Control (age-matched). The lactation period was 12days, then the pups were removed, and thereafter recovery took place for 28days. Zln, 100μg/kg, was given s.c. on the day of delivery, and again 4 and 8days later. Mechanical testing, μCT, and dynamic histomorphometry were performed. At L4, lactation resulted in a substantial loss of bone strength (-55% vs. Pregnant, p<0.01), BV/TV (-40% vs. Pregnant, p<0.01), and trabecular thickness (Tb.Th) (-29% vs. Pregnant, p<0.001). Treatment with Zln completely prevented lactation induced loss of bone strength, BV/TV, and Tb.Th at L4. Full recovery of micro-architectural and mechanical properties was found 28days after weaning in vehicle-treated mice. Interestingly, the recovery group treated with Zln during the lactation period had higher BV/TV (+45%, p<0.01) and Tb.Th (+16%, p<0.05) compared with virgin controls. Similar results were found at the proximal tibia and femur. This indicates that Zln did not interfere with the bone formation taking place after weaning. On this background, we conclude that post-lactation bone formation is not dependent on a preceding lactation induced bone loss. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of imbalanced muscle loading on hip joint development and maturation.

PubMed

Ford, Caleb A; Nowlan, Niamh C; Thomopoulos, Stavros; Killian, Megan L

2017-05-01

The mechanical loading environment influences the development and maturation of joints. In this study, the influence of imbalanced muscular loading on joint development was studied using localized chemical denervation of hip stabilizing muscle groups in neonatal mice. It was hypothesized that imbalanced muscle loading, targeting either gluteal muscles or quadriceps muscles, would lead to bilateral hip joint asymmetry, as measured by acetabular coverage, femoral head volume and bone morphometry, and femoral-acetabular shape. The contralateral hip joints as well as age-matched, uninjected mice were used as controls. Altered bone development was analyzed using micro-computed tomography, histology, and image registration techniques at postnatal days (P) 28, 56, and 120. This study found that unilateral muscle unloading led to reduced acetabular coverage of the femoral head, lower total volume, lower bone volume ratio, and lower mineral density, at all three time points. Histologically, the femoral head was smaller in unloaded hips, with thinner triradiate cartilage at P28 and thinner cortical bone at P120 compared to contralateral hips. Morphological shape changes were evident in unloaded hips at P56. Unloaded hips had lower trabecular thickness and increased trabecular spacing of the femoral head compared to contralateral hips. The present study suggests that decreased muscle loading of the hip leads to altered bone and joint shape and growth during postnatal maturation. Statement of Clinical Significance: Adaptations from altered muscle loading during postnatal growth investigated in this study have implications on developmental hip disorders that result from asymmetric loading, such as patients with limb-length inequality or dysplasia. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1128-1136, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Bisphosphonates as a Countermeasure to Space Flight Induced Bone Loss

NASA Technical Reports Server (NTRS)

LeBlanc, Adrian; Matsumoto, Toshio; Jones, Jeff; Shapiro, Jay; Lang, Tom; Smith, Scott M.; Shackelford, Linda C.; Sibonga, Jean; Evans, Harlan; Spector, Elisabeth;

Short-term, daily exposure to cold temperature may be an efficient way to prevent muscle atrophy and bone loss in a microgravity environment

NASA Astrophysics Data System (ADS)

Deng, Claudia; Wang, Ping; Zhang, Xiangming; Wang, Ya

2015-04-01

Microgravity induces less pressure on muscle/bone, which is a major reason for muscle atrophy as well as bone loss. Currently, physical exercise is the only countermeasure used consistently in the U.S. human space program to counteract the microgravity-induced skeletal muscle atrophy and bone loss. However, the routinely almost daily time commitment is significant and represents a potential risk to the accomplishment of other mission operational tasks. Therefore, development of more efficient exercise programs (with less time) to prevent astronauts from muscle atrophy and bone loss are needed. Consider the two types of muscle contraction: exercising forces muscle contraction and prevents microgravity-induced muscle atrophy/bone loss, which is a voluntary response through the motor nervous system; and cold temperature exposure-induced muscle contraction is an involuntary response through the vegetative nervous system, we formed a new hypothesis. The main purpose of this pilot study was to test our hypothesis that exercise at 4 °C is more efficient than at room temperature to prevent microgravity-induced muscle atrophy/bone loss and, consequently reduces physical exercise time. Twenty mice were divided into two groups with or without daily short-term (10 min × 2, at 12 h interval) cold temperature (4 °C) exposure for 30 days. The whole bodyweight, muscle strength and bone density were measured after terminating the experiments. The results from the one-month pilot study support our hypothesis and suggest that it would be reasonable to use more mice, in a microgravity environment and observe for a longer period to obtain a conclusion. We believe that the results from such a study will help to develop efficient exercise, which will finally benefit astronauts' heath and NASA's missions.

Short-term, daily exposure to cold temperature may be an efficient way to prevent muscle atrophy and bone loss in a microgravity environment

PubMed Central

Deng, Claudia; Wang, Ping; Zhang, Xiangming; Wang, Ya

2015-01-01

Microgravity induces less pressure on muscle/bone, which is a major reason for muscle atrophy as well as bone loss. Currently, physical exercise is the only countermeasure used consistently in the U.S. human space program to counteract the microgravity-induced skeletal muscle atrophy and bone loss. However, the routinely almost daily time commitment is significant and represents a potential risk to the accomplishment of other mission operational tasks. Therefore, development of more efficient exercise programs (with less time) to prevent astronauts from muscle atrophy and bone loss are needed. Consider the two types of muscle contraction: exercising forces muscle contraction and prevents microgravity-induced muscle atrophy/bone loss, which is a voluntary response through the motor nervous system; and cold temperature exposure-induced muscle contraction is an involuntary response through the vegetative nervous system, we formed a new hypothesis. The main purpose of this pilot study was to test our hypothesis that exercise at 4°C is more efficient than at room temperature to prevent microgravity-induced muscle atrophy/bone loss and, consequently reduces physical exercise time. Twenty mice were divided into two groups with or without daily short-term (10 min × 2, at 12 h interval) cold temperature (4°C) exposure for 30 days. The whole bodyweight, muscle strength and bone density were measured after terminating the experiments. The results from the one-month pilot study support our hypothesis and suggest that it would be reasonable to use more mice, in a microgravity environment and observe for a longer period to obtain a conclusion. We believe that the results from such a study will help to develop efficient exercise, which will finally benefit astronauts’ heath and NASA’s mission. PMID:25821722

Mechanical Unloading of Mouse Bone in Microgravity Significantly Alters Cell Cycle Gene Set Expression

NASA Astrophysics Data System (ADS)

Blaber, Elizabeth; Dvorochkin, Natalya; Almeida, Eduardo; Kaplan, Warren; Burns, Brnedan

2012-07-01

Spaceflight factors, including microgravity and space radiation, have many detrimental short-term effects on human physiology, including muscle and bone degradation, and immune system dysfunction. The long-term progression of these physiological effects is still poorly understood, and a serious concern for long duration spaceflight missions. We hypothesized that some of the degenerative effects of spaceflight may be caused in part by an inability of stem cells to proliferate and differentiate normally resulting in an impairment of tissue regenerative processes. Furthermore, we hypothesized that long-term bone tissue degeneration in space may be mediated by activation of the p53 signaling network resulting in cell cycle arrest and/or apoptosis in osteoprogenitors. In our analyses we found that spaceflight caused significant bone loss in the weight-bearing bones of mice with a 6.3% reduction in bone volume and 11.9% decrease in bone thickness associated with increased osteoclastic activity. Along with this rapid bone loss we also observed alterations in the cell cycle characterized by an increase in the Cdkn1a/p21 cell cycle arrest molecule independent of Trp53. Overexpression of Cdkn1a/p21 was localized to osteoblasts lining the periosteal surface of the femur and chondrocytes in the head of the femur, suggesting an inhibition of proliferation in two key regenerative cell types of the femur in response to spaceflight. Additionally we found overexpression of several matrix degradation molecules including MMP-1a, 3 and 10, of which MMP-10 was localized to osteocytes within the shaft of the femur. This, in conjunction with 40 nm resolution synchrotron nano-Computed Tomography (nano-CT) observations of an increase in osteocyte lacunae cross-sectional area, perimeter and a decrease in circularity indicates a potential role for osteocytic osteolysis in the observed bone degeneration in spaceflight. To further investigate the genetic response of bone to mechanical unloading in spaceflight, we conducted genome wide microarray analysis of total RNA isolated from the mouse pelvis. Specifically, 16 week old mice were subjected to 15 days spaceflight onboard NASA's STS-131 space shuttle mission. The pelvis of the mice was dissected, the bone marrow was flushed and the bones were briefly stored in RNAlater. The pelvii were then homogenized, and RNA was isolated using TRIzol. RNA concentration and quality was measured using a Nanodrop spectrometer, and 0.8% agarose gel electrophoresis. Samples of cDNA were analyzed using an Affymetrix GeneChip\\S Gene 1.0 ST (Sense Target) Array System for Mouse and GenePattern Software. We normalized the ST gene arrays using Robust Multichip Average (RMA) normalization, which summarizes perfectly matched spots on the array through the median polish algorithm, rather than normalizing according to mismatched spots. We also used Limma for statistical analysis, using the BioConductor Limma Library by Gordon Smyth, and differential expression analysis to identify genes with significant changes in expression between the two experimental conditions. Finally we used GSEApreRanked for Gene Set Enrichment Analysis (GSEA), with Kolmogorov-Smirnov style statistics to identify groups of genes that are regulated together using the t-statistics derived from Limma. Preliminary results show that 6,603 genes expressed in pelvic bone had statistically significant alterations in spaceflight compared to ground controls. These prominently included cell cycle arrest molecules p21, and p18, cell survival molecule Crbp1, and cell cycle molecules cyclin D1, and Cdk1. Additionally, GSEA results indicated alterations in molecular targets of cyclin D1 and Cdk4, senescence pathways resulting from abnormal laminin maturation, cell-cell contacts via E-cadherin, and several pathways relating to protein translation and metabolism. In total 111 gene sets out of 2,488, about 4%, showed statistically significant set alterations. These alterations indicate significant impairment of normal cellular function in the mechanically unloaded environment of space and could provide important genetic insight into the observed uncoupling of bone formation and resorption in space.

Massive Bone Loss Due to Orchidectomy and Localized Disuse: Preventive Effects of a Biosphonsphonate

NASA Astrophysics Data System (ADS)

Libouban, H.; Moreau, M. F.; Chappard, D.

2008-06-01

Orchidectomy (ORX) and hindlimb paralysis induced by botulinum neurotoxin (BTX) were combined to see if their effects were cumulative and if bone loss could be prevented by an antiresorptive agent (risedronate) or testosterone. Four groups of mature rats were studied for 1 month: SHAM operated; ORX and right hindlimb immobilization (BTX); ORX+BTX+risedronate or testosterone. Bone loss and microarchitecture deterioration were maximized on the immobilized bone. Risedronate but not testosterone prevented trabecular bone loss but was less effective on cortical bone loss. ORX and BTX had additive effects on bone loss which can be prevented by risedronate but not testosterone.

Prostaglandin E2 Prevents Ovariectomy-Induced Cancellous Bone Loss in Rats

NASA Technical Reports Server (NTRS)

Ke, Hua Zhu; Li, Mei; Jee, Webster S. S.

1992-01-01

The object of this study was to determine whether prostaglandin E2, (PGE2) can prevent ovariectomy induced cancellous bone loss. Thirty-five 3-month-old female Sprague-Dawley rats were divided into two groups. The rats in the first group were ovariectomized (OVX) while the others received sham operation (sham-OVX). The OVX group was further divided into three treatment groups. The daily doses for the three groups were 0,1 and 6 mg PGE2/kg for 90 days. Bone histomorphometric analyses were performed on double-fluorescent-labeled undecalcified proximal tibial metaphysis (PTM). We confirmed that OVX induces massive cancellous bone loss (-80%) and a higher bone turnover (+143%). The new findings from the present study demonstrate that bone loss due to ovarian hormone deficiency can be prevented by a low-dose (1 mg) daily administration of PGE2. Furthermore, a higher-dose (6 mg) daily administration of PGE2 not only prevents bone loss but also adds extra bone to the proximal tibial metaphyses. PGE, at the 1-mg dose level significantly increased trabecular bone area, trabecular width, trabecular node density, density of node to node, ratio of node to free end, and thus significantly decreased trabecular separation from OVX controls. At this dose level, these same parameters did not differ significantly from sham-OVX controls. However, at the 6-mg dose level PGE2, there were significant increases in trabecular bone area, trabecular width, trabecular node density, density of node to node, and ratio of node to free end, while there was significant decrease in trabecular separation from both OVX and sham-operated controls. The changes in indices of trabecular bone microanatomical structure indicated that PGE2 prevented bone loss as well as the disconnection of existing trabeculae. In summary, PGE2, administration to OVX rats decreased bone turnover and increased bone formation parameters resulting in a positive bone balance that prevented bone loss (in both lower and higher doses) and added extra bone to metaphyses of OVX rats (in higher dose). These findings support the strategy of the use of bone stimulation agents in the prevention of estrogen depletion bone loss (postmenopausal osteoporosis).

Synergistic Phytochemicals Fail to Protect Against Ovariectomy Induced Bone Loss in Rats.

PubMed

Ambati, Suresh; Miller, Colette N; Bass, Erica F; Hohos, Natalie M; Hartzell, Diane L; Kelso, Emily W; Trunnell, Emily R; Yang, Jeong-Yeh; Della-Fera, Mary Anne; Baile, Clifton A; Rayalam, Srujana

2018-05-24

Menopause induces a loss of bone as a result of estrogen deficiency. Despite pharmaceutical options for the treatment of osteopenia and osteoporosis, many aging women use dietary supplements with estrogenic activity to prevent bone loss and other menopausal-related symptoms. Such supplements are yet to be tested for efficacy against a Food and Drug Administration (FDA) approved medication for menopausal bone loss such as zoledronic acid (ZA). The postmenopausal rat model was used to investigate the efficacy of various synergistic phytochemical blends mixed into the diet for 16 weeks. Retired-breeder, Fischer 344 rats were randomly assigned to sham or ovariectomy surgery and 4 treatment groups: ZA; genistein supplementation; and a low dose and high dose blend of genistein, resveratrol, and quercetin. Ovariectomy resulted in a loss of both trabecular and cortical bone which was prevented with ZA. The phytochemical blends tested were unable to reverse these losses. Despite the lack of effectiveness in preventing bone loss, a significant dose-response trend was observed in the phytochemical-rich diets in bone adipocyte number compared to ovariectomized control rats. Data from this study indicate that estrogenic phytochemicals are not as efficacious as ZA in preventing menopausal-related bone loss but may have beneficial effects on bone marrow adiposity in rats.

Calcium and bone metabolism during space flight

NASA Technical Reports Server (NTRS)

Smith, Scott M.; Heer, Martina

2002-01-01

Weightlessness induces bone loss. Understanding the nature of this loss and developing means to counteract it are significant challenges to potential human exploration missions. This article reviews the existing information from studies of bone and calcium metabolism conducted during space flight. It also highlights areas where nutrition may play a specific role in this bone loss, and where countermeasures may be developed to mitigate that loss.

Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

DOE PAGES

Jamison, Ryan Dale; Shen, Yu -Lin

2015-08-13

Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayermore » material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.« less

iNOS-Derived Nitric Oxide Stimulates Osteoclast Activity and Alveolar Bone Loss in Ligature-Induced Periodontitis in Rats

PubMed Central

Herrera, Bruno S.; Martins-Porto, Rodrigo; Maia-Dantas, Aline; Campi, Paula; Spolidorio, Luis C.; Costa, Soraia K.P.; Van Dyke, Thomas E.; Gyurko, Robert; Muscara, Marcelo N.

2012-01-01

Background Inflammatory stimuli activate inducible nitric oxide synthase (iNOS) in a variety of cell types, including osteoclasts (OC) and osteoblasts, resulting in sustained NO production. In this study, we evaluate the alveolar bone loss in rats with periodontitis under long-term iNOS inhibition, and the differentiation and activity of OC from iNOS-knockout (KO) mice in vitro. Methods Oral aminoguanidine (an iNOS inhibitor) or water treatment was started 2 weeks before induction of periodontitis. Rats were sacrificed 3, 7, or 14 days after ligature placement, and alveolar bone loss was evaluated. In vitro OC culture experiments were also performed to study the differentiation of freshly isolated bone marrow cells from both iNOS KO and wild-type C57BL/6 mice. OC were counted 6 days later after tartrate-resistant acid phosphatase staining (a marker of osteoclast identity), and bone resorption activity was assessed by counting the number of resorption pits on dentin disks. Results Rats with ligature showed progressive and significant alveolar bone loss compared to sham animals, and aminoguanidine treatment significantly inhibited ligature-induced bone loss at 7 and 14 days after the induction. In comparison to bone marrow cells from wild-type mice, cells from iNOS KO mice showed decreased OC growth and the resulting OC covered a smaller culture dish area and generated fewer resorption pit counts. Conclusion Our results demonstrate that iNOS inhibition prevents alveolar bone loss in a rat model of ligature-induced periodontitis, thus confirming that iNOS-derived NO plays a crucial role in the pathogenesis of periodontitis, probably by stimulating OC differentiation and activity. PMID:21417589

Hematopoietic Stem Cell Therapy as a Counter-Measure for Human Exploration of Deep Space

NASA Technical Reports Server (NTRS)

Ohi, S.; Roach, A.-N.; Ramsahai, S.; Kim, B. C.; Fitzgerald, W.; Riley, D. A.; Gonda, S. R.

2004-01-01

Human exploration of deep space depends, in part, on our ability to counter severe/invasive disorders that astronauts experience in space environments. The known symptoms include hematological/cardiac abnormalities,bone and muscle losses, immunodeficiency, neurological disorders, and cancer. Exploiting the extraordinary plasticity of hematopoietic stem cells (HSCs), which differentiate not only to all types of blood cells, but also to various tissues, we have advanced a hypothesis that ome of the space-caused disorders maybe amenable to hematopoietis stem cell therapy(HSCT) so as to maintain promote human exploration of deep space. Using mouse models of human anemia beta-thaiassemia) as well as spaceflight (hindlimb unloading system), we have obtained feasibility results of HSCT for space anemia, muscle loss, and immunodeficiency. For example, in the case of HSCT for muscle loss, the beta-galactosidese marked HSCs were detected in the hindlimbs of unloaded mouse following transplantation by -X-gal wholemaunt staining procedure. Histochemicaland physical analyses indicated structural contribution of HSCs to the muscle. HSCT for immunodeficiency was investigated ising beta-galactosidese gene-tagged Escherichia coli as the infectious agent. Results of the X-gal staining procedure indicated the rapeutic role of the HSCT. To facilitate the HSCT in space, growth of HSCs were optimized in the NASA Rotating Wall Vessel (RWV) culture systems, including Hydrodynamic Focusing Bioreactor (HFB).

Time Course of Peri-Implant Bone Regeneration around Loaded and Unloaded Implants in a Rat Model

PubMed Central

Jariwala, Shailly H.; Wee, Hwabok; Roush, Evan P.; Whitcomb, Tiffany L.; Murter, Christopher; Kozlansky, Gery; Lakhtakia, Akhlesh; Kunselman, Allen R.; Donahue, Henry J.; Armstrong, April D.; Lewis, Gregory S.

2018-01-01

The time-course of cancellous bone regeneration surrounding mechanically loaded implants affects implant fixation, and is relevant to determining optimal rehabilitation protocols following orthopaedic surgeries. We investigated the influence of controlled mechanical loading of titanium-coated polyether-ether ketone (PEEK) implants on osseointegration using time-lapsed, non-invasive, in vivo micro-computed tomography (micro-CT) scans. Implants were inserted into proximal tibial metaphyses of both limbs of eight female Sprague-Dawley rats. External cyclic loading (60 μm or 100 μm displacement, 1 Hz, 60 seconds) was applied every other day for 14 days to one implant in each rat, while implants in contralateral limbs served as the unloaded controls. Hind limbs were imaged with high-resolution micro-CT (12.5 μm voxel size) at 2, 5, 9, and 12 days post-surgery. Trabecular changes over time were detected by 3D image registration allowing for measurements of bone-formation rate (BFR) and bone-resorption rate (BRR). At day 9, mean %BV/TV for loaded and unloaded limbs were 35.5 ± 10.0 % and 37.2 ± 10.0 %, respectively, and demonstrated significant increases in bone volume compared to day 2. BRR increased significantly after day 9. No significant differences between bone volumes, BFR, and BRR were detected due to implant loading. Although not reaching significance (p = 0.16), an average 119 % increase in pull-out strength was measured in the loaded implants. PMID:27381807

Transplantation of osteoporotic bone marrow stromal cells rejuvenated by the overexpression of SATB2 prevents alveolar bone loss in ovariectomized rats.

PubMed

Xu, Rongyao; Fu, Zongyun; Liu, Xue; Xiao, Tao; Zhang, Ping; Du, Yifei; Yuan, Hua; Cheng, Jie; Jiang, Hongbing

2016-11-01

Estrogen-deficient osteoporosis is an aging-related disease with high morbidity that not only significantly increases a woman's risk of fragility fracture but is also associated with tooth and bone loss in the supporting alveolar bone of the jaw. Emerging evidence suggests that the aging of bone marrow stromal cells (BMSCs) contributes to the development of osteoporosis. In this study, we aimed to investigate the role of the special AT-rich sequence-binding protein 2 (SATB2), a stemness and senescence regulator of craniofacial BMSCs, in rat ovariectomy-induced alveolar osteoporosis. We also sought to determine whether transplantation of SATB2-modified BMSCs could ameliorate estrogen deficient alveolar bone loss. Our data revealed that BMSCs from ovariectomy-induced alveolar bone exhibited typical senescence phenotypes such as diminished stemness and osteogenic capacity, increased expression of senescence or osteoclastic markers and enhanced adipogenic potential. These phenotypic changes are a result of SATB2-mediated senescence dysregulation as evidenced by nuclear γH2AX foci formation. Moreover, overexpression of SATB2 significantly alleviated the senescence of osteoporotic BMSCs in vitro. Importantly, transplantation of SATB2-modified BMSCs significantly attenuated ovariectomy-induced alveolar bone loss in vivo. Together, our results revealed that SATB2 is a critical regulator of alveolar BMSC senescence, and its overexpression decreases these senescent changes both in vitro and in vivo. SATB2-modified BMSC delivery could be a viable and promising therapeutic strategy for alveolar bone loss induced by estrogen-deficient osteoporosis. Copyright © 2016 Elsevier Inc. All rights reserved.

Bone Blood Flow During Simulated Microgravity: Physiological and Molecular Mechanisms

NASA Technical Reports Server (NTRS)

Bloomfield, Susan A.

1999-01-01

Blood flow to bone has been shown to affect bone mass and presumably bone strength. Preliminary data indicate that blood flow to the rat femur decreases after 14 days of simulated microgravity, using hindlimb suspension (HLS). If adult rats subjected to HLS are given dobutamine, a synthetic catecholamine which can cause peripheral vasodilation and increased blood flow, the loss of cortical bone area usually observed is prevented. Further, mechanisms exist at the molecular level to link changes in bone blood flow to changes in bone cell activity, particularly for vasoactive agents like nitric oxide (NO). The decreases in fluid shear stress created by fluid flow associated with the shifts of plasma volume during microgravity may result in alterations in expression of vasoactive agents such as NO, producing important functional effects on bone cells. The primary aim of this project is to characterize changes in 1) bone blood flow, 2) indices of bone mass, geometry, and strength, and 3) changes in gene expression for modulators of nitric oxide activity (e.g., nitric oxide synthase) and other candidate genes involved in signal transduction of mechanical loading after 3, 7, 14, 21, and 28 days of HLS in the adult rat. Using a rat of at least 5 months of age avoids inadvertently studying effects of simulated microgravity on growing, rather than adult, bone. Utilizing the results of these studies, we will then define how altered blood flow contributes to changes in bone with simulated microgravity by administering a vasodilatory agent (which increases blood flow to tissues) during hindlimb suspension. In all studies, responses in the unloaded hindlimb bones (tibial shaft, femoral neck) will be compared with those in the weightbearing humeral shaft and the non-weightbearing calvarium (skull) from the same animal. Bone volumetric mineral density and geometry will be quantified by peripheral quantitative CT; structural and material properties of the long bones will be determined by 3-point bending (tibia, humerus) or compression (femoral neck) testing to failure. A unique aspect of these studies will be defining the time course of changes in gene expression in bone cell populations with unloading, accomplished with Northern blots, in situ hybridization, and immunohistochemistry. These studies have high relevance for concurrent protocols being proposed by investigators on NSBRI Cardiovascular and Muscle teams, with blood flow data available on a number of tissues other than bone. Further, dobutamine and other Beta-agonists have been tested as countermeasures for altered muscle and cardiovascular function. Results of the intervention tested in our studies have potential relevance for a number of systemic changes seen with prolonged spaceflight.

Probiotics Protect Mice from Ovariectomy-Induced Cortical Bone Loss

PubMed Central

Ohlsson, Claes; Engdahl, Cecilia; Fåk, Frida; Andersson, Annica; Windahl, Sara H.; Farman, Helen H.; Movérare-Skrtic, Sofia; Islander, Ulrika; Sjögren, Klara

2014-01-01

The gut microbiota (GM) modulates the hosts metabolism and immune system. Probiotic bacteria are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host and can alter the composition of the GM. Germ-free mice have increased bone mass associated with reduced bone resorption indicating that the GM also regulates bone mass. Ovariectomy (ovx) results in bone loss associated with altered immune status. The purpose of this study was to determine if probiotic treatment protects mice from ovx-induced bone loss. Mice were treated with either a single Lactobacillus (L) strain, L. paracasei DSM13434 (L. para) or a mixture of three strains, L. paracasei DSM13434, L. plantarum DSM 15312 and DSM 15313 (L. mix) given in the drinking water during 6 weeks, starting two weeks before ovx. Both the L. para and the L. mix treatment protected mice from ovx-induced cortical bone loss and bone resorption. Cortical bone mineral content was higher in both L. para and L. mix treated ovx mice compared to vehicle (veh) treated ovx mice. Serum levels of the resorption marker C-terminal telopeptides and the urinary fractional excretion of calcium were increased by ovx in the veh treated but not in the L. para or the L. mix treated mice. Probiotic treatment reduced the expression of the two inflammatory cytokines, TNFα and IL-1β, and increased the expression of OPG, a potent inhibitor of osteoclastogenesis, in cortical bone of ovx mice. In addition, ovx decreased the frequency of regulatory T cells in bone marrow of veh treated but not probiotic treated mice. In conclusion, treatment with L. para or the L. mix prevents ovx-induced cortical bone loss. Our findings indicate that these probiotic treatments alter the immune status in bone resulting in attenuated bone resorption in ovx mice. PMID:24637895

Probiotics protect mice from ovariectomy-induced cortical bone loss.

PubMed

Ohlsson, Claes; Engdahl, Cecilia; Fåk, Frida; Andersson, Annica; Windahl, Sara H; Farman, Helen H; Movérare-Skrtic, Sofia; Islander, Ulrika; Sjögren, Klara

2014-01-01

The gut microbiota (GM) modulates the hosts metabolism and immune system. Probiotic bacteria are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host and can alter the composition of the GM. Germ-free mice have increased bone mass associated with reduced bone resorption indicating that the GM also regulates bone mass. Ovariectomy (ovx) results in bone loss associated with altered immune status. The purpose of this study was to determine if probiotic treatment protects mice from ovx-induced bone loss. Mice were treated with either a single Lactobacillus (L) strain, L. paracasei DSM13434 (L. para) or a mixture of three strains, L. paracasei DSM13434, L. plantarum DSM 15312 and DSM 15313 (L. mix) given in the drinking water during 6 weeks, starting two weeks before ovx. Both the L. para and the L. mix treatment protected mice from ovx-induced cortical bone loss and bone resorption. Cortical bone mineral content was higher in both L. para and L. mix treated ovx mice compared to vehicle (veh) treated ovx mice. Serum levels of the resorption marker C-terminal telopeptides and the urinary fractional excretion of calcium were increased by ovx in the veh treated but not in the L. para or the L. mix treated mice. Probiotic treatment reduced the expression of the two inflammatory cytokines, TNFα and IL-1β, and increased the expression of OPG, a potent inhibitor of osteoclastogenesis, in cortical bone of ovx mice. In addition, ovx decreased the frequency of regulatory T cells in bone marrow of veh treated but not probiotic treated mice. In conclusion, treatment with L. para or the L. mix prevents ovx-induced cortical bone loss. Our findings indicate that these probiotic treatments alter the immune status in bone resulting in attenuated bone resorption in ovx mice.

Change in Mouse Bone Turnover in Response to Microgravity on RR-1

NASA Technical Reports Server (NTRS)

Cheng-Campbell, Margareth A.; Blaber, Elizabeth A.; Almeida, Eduardo A. C.

2016-01-01

Mechanical unloading during spaceflight is known to adversely affect mammalian physiology. Our previous studies using the Animal Enclosure Module on short duration Shuttle missions enabled us to identify a deficit in stem cell based-tissue regeneration as being a significant concern for long-duration spaceflight. Specifically, we found that mechanical unloading in microgravity resulted in inhibition of differentiation of mesenchymal and hematopoietic stem cells in the bone marrow compartment. Also, we observed overexpression of a cell cycle arrest molecule, CDKN1ap21, in osteoprecursor cells on the bone surface, chondroprogenitors in the articular cartilage, and in myofibers attached to bone tissue. Specifically in bone tissue during both short (15-day) and long (30-day) microgravity experiments, we observed significant loss of bone tissue and structure in both the pelvis and the femur. After 15-days of microgravity on STS-131, pelvic ischium displayed a 6.23 decrease in bone fraction (p0.005) and 11.91 decrease in bone thickness (p0.002). Furthermore, during long-duration spaceflight we observed onset of an accelerated aging-like phenotype and osteoarthritic disease state indicating that stem cells within the bone tissue fail to repair and regenerate tissues in a normal manner, leading to drastic tissue alterations in response to microgravity. The Rodent Research Hardware System provides the capability to investigate these effects during long-duration experiments on the International Space Station. During the Rodent Research-1 mission 10 16-week-old female C57Bl6J mice were exposed to 37-days of microgravity. All flight animals were euthanized and frozen on orbit for future dissection. Ground (n10) and vivarium controls (n10) were housed and processed to match the flight animal timeline. During this study we collected pelvis, femur, and tibia from all animal groups to test the hypothesis that stem cell-based tissue regeneration is significantly altered after 37-days of spaceflight. To do this, we will analyze differences in bone morphometric parameters using MicroCT. The pelvis, femur, and tibia are key in supporting and distributing weight under normal conditions. Therefore, we expect to see altered remodeling in flight animals in response to microgravity with respect to ground controls. In combination with histomorphometry, these results will help elucidate the complex mechanisms underlying bone tissue maintenance and stem cell regeneration.

Changes in Mouse Bone Turnover in Response to Microgravity

NASA Technical Reports Server (NTRS)

Cheng-Campbell, M.; Blaber, E.; Almeida, E.

2016-01-01

Mechanical unloading during spaceflight is known to adversely affect mammalian physiology. Our previous studies using the Animal Enclosure Module on short duration Shuttle missions enabled us to identify a deficit in stem cell based-tissue regeneration as being a significant concern for long-duration spaceflight. Specifically, we found that mechanical unloading in microgravity resulted in inhibition of differentiation of mesenchymal and hematopoietic stem cells in the bone marrow compartment. Also, we observed overexpression of a cell cycle arrest molecule, CDKN1a/p21, in osteoprecursor cells on the bone surface, chondroprogenitors in the articular cartilage, and in myofibers attached to bone tissue. Specifically in bone tissue during both short (15-day) and long (30-day) microgravity experiments, we observed significant loss of bone tissue and structure in both the pelvis and the femur. After 15-days of microgravity on STS-131, pelvic ischium displayed a 6.23% decrease in bone fraction (p=0.005) and 11.91% decrease in bone thickness (p=0.002). Furthermore, during long-duration spaceflight we observed onset of an accelerated aging-like phenotype and osteoarthritic disease state indicating that stem cells within the bone tissue fail to repair and regenerate tissues in a normal manner, leading to drastic tissue alterations in response to microgravity. The Rodent Research Hardware System provides the capability to investigate these effects during long-duration experiments on the International Space Station. During the Rodent Research-1 mission 10 16-week-old female C57Bl/6J mice were exposed to 37-days of microgravity. All flight animals were euthanized and frozen on orbit for future dissection. Ground (n=10) and vivarium controls (n=10) were housed and processed to match the flight animal timeline. During this study we collected pelvis, femur, and tibia from all animal groups to test the hypothesis that stem cell-based tissue regeneration is significantly altered after 37-days of spaceflight. To do this, we will analyze differences in bone morphometric parameters using MicroCT. The pelvis, femur, and tibia are key in supporting and distributing weight under normal conditions. Therefore, we expect to see altered remodeling in flight animals in response to microgravity with respect to ground controls. In combination with histomorphometry, these results will help elucidate the complex mechanisms underlying bone tissue maintenance and stem cell regeneration.

Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss

NASA Technical Reports Server (NTRS)

Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

2012-01-01

Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

Involvement of Cot/Tp12 in bone loss during periodontitis.

PubMed

Ohnishi, T; Okamoto, A; Kakimoto, K; Bandow, K; Chiba, N; Matsuguchi, T

2010-02-01

Periodontitis causes resorption of alveolar bone, in which RANKL induces osteoclastogenesis. The binding of lipopolysaccharide to Toll-like receptors causes phosphorylation of Cot/Tp12 to activate the MAPK cascade. Previous in vitro studies showed that Cot/Tp12 was essential for the induction of RANKL expression by lipopolysaccharide. In this study, we examined whether Cot/Tp12 deficiency reduced the progression of alveolar bone loss and osteoclastogenesis during experimental periodontitis. We found that the extent of alveolar bone loss and osteoclastogenesis induced by ligature-induced periodontitis was decreased in Cot/Tp12-deficient mice. In addition, reduction of RANKL expression was observed in periodontal tissues of Cot/Tp12-deficient mice with experimental periodontitis. Furthermore, we found that Cot/Tp12 was involved in the induction of TNF-alpha mRNA expression in gingiva of mice with experimental periodontitis. Our observations suggested that Cot/Tp12 is essential for the progression of alveolar bone loss and osteoclastogenesis in periodontal tissue during experimental periodontitis mediated through increased RANKL expression.

BMI-1 Mediates Estrogen-Deficiency-Induced Bone Loss by Inhibiting Reactive Oxygen Species Accumulation and T Cell Activation.

PubMed

Li, Jinbo; Wang, Qian; Yang, Renlei; Zhang, Jiaqi; Li, Xing; Zhou, Xichao; Miao, Dengshun

2017-05-01

Previous studies have shown that estrogen regulates bone homeostasis through regulatory effects on oxidative stress. However, it is unclear how estrogen deficiency triggers reactive oxygen species (ROS) accumulation. Recent studies provide evidence that the B lymphoma Mo-MLV insertion region 1 (BMI-1) plays a critical role in protection against oxidative stress and that this gene is directly regulated by estrogen via estrogen receptor (ER) at the transcriptional level. In this study, ovariectomized mice were given drinking water with/without antioxidant N-acetyl-cysteine (NAC, 1 mg/mL) supplementation, and compared with each other and with sham mice. Results showed that ovariectomy resulted in bone loss with increased osteoclast surface, increased ROS levels, T cell activation, and increased TNF and RANKL levels in serum and in CD4 T cells; NAC supplementation largely prevented these alterations. BMI-1 expression levels were dramatically downregulated in CD4 T cells from ovariectomized mice. We supplemented drinking water to BMI-1-deficient mice with/without NAC and compared them with each other and with wild-type (WT) mice. We found that BMI-1 deficiency mimicked alterations observed in ovariectomy whereas NAC supplementation reversed all alterations induced by BMI-1 deficiency. Because T cells are critical in mediating ovariectomy-induced bone loss, we further assessed whether BMI-1 overexpression in lymphocytes can protect against estrogen deficiency-induced osteoclastogenesis and bone loss by inhibiting oxidative stress, T cell activation, and RANKL production. When WT and Eμ-BMI-1 transgenic mice with BMI-1 specifically overexpressed in lymphocytes were ovariectomized and compared with each other and with WT sham mice, we found that BMI-1 overexpression in lymphocytes clearly reversed all alterations induced by ovariectomy. Results from this study indicate that estrogen deficiency downregulates BMI-1 and subsequently increases ROS, T cell activation, and RANKL production in T cells, thus enhancing osteoclastogenesis and accelerating bone loss. This study clarifies a novel mechanism regulating estrogen deficiency-induced bone loss. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

Simulating certain aspects of hypogravity - Effects on bone maturation in the nonweight bearing skeleton

NASA Technical Reports Server (NTRS)

Simmons, D. J.; Grazman, B.; Russell, J. E.; Walker, W. V.; Bikle, D. D.; Morey, E. R.

1983-01-01

For a determination of how the nonweight-bearing skeletons, i.e., lower jaws, of 41-day and 1-year old rats would respond to 10 or 14 days of partial skeletal unloading by elevating the hindquarters (PULEH), an experimental system to simulate the fluid shifts and unloading of portions of the skeleton which occur during spaceflight was developed. In comparison with the bone matrix mineralization recorded in the mandibles of rats flown in the Soviet 18.5 day Cosmos-1129 mission, the PULEH studies failed to produce spaceflight-like maturation defects.

Exercise training in obese older adults prevents increase in bone turnover and attenuates decrease in hip BMD induced by weight loss despite decline in bone-active hormones*

PubMed Central

Shah, Krupa; Armamento-Villareal, Reina; Parimi, Nehu; Chode, Suresh; Sinacore, David R.; Hilton, Tiffany N.; Napoli, Nicola; Qualls, Clifford; Villareal, Dennis T.

2011-01-01

Weight-loss therapy to improve health in obese older adults is controversial because it causes further bone loss. Therefore, it is recommended that weight-loss therapy should include an intervention to minimize bone loss such as exercise training (ET). The purpose of this study was to determine the independent and combined effects of weight loss and ET on bone metabolism in relation to bone mineral density (BMD) in obese older adults. One-hundred-seven older (age >65 yrs) obese (BMI ≥30 kg/m2) adults were randomly assigned to a control group, diet group, exercise group, and diet-exercise group for 1 year. Body weight decreased in the diet (−9.6%) and diet-exercise (−9.4%) groups, not in the exercise (−1%) and control (−0.2%) groups (between-group P<.001). However, despite comparable weight loss, bone loss at the total hip was relatively less in the diet-exercise group (−1.1%) than in the diet group (−2.6%), whereas BMD increased in the exercise group (1.5%) (between-group P<.001) Serum C-terminal telopeptide (CTX) and osteocalcin concentrations increased in the diet group (31% and 24%) while they decreased in the exercise group (−13% and −15%) (between-group P<.001). In contrast, similar to the control group, serum CTX and osteocalcin concentrations did not change in the diet-exercise group. Serum procollagen propeptide concentrations decreased in the exercise group (−15%) compared with the diet group (9%) (P=.04). Serum leptin and estradiol concentrations decreased in the diet (−25% and −15%) and diet-exercise (−38% and −13%) groups, not in the exercise and control groups (between-group P=.001). Multivariate analyses revealed that changes in lean body mass (β=.33), serum osteocalcin (β= −.24), and 1-RM strength (β=.23) were independent predictors of changes in hip BMD (all P<.05). In conclusion, the addition of ET to weight-loss therapy among obese older adults prevents weight-loss-induced increase in bone turnover and attenuates weight-loss-induced reduction in hip BMD despite weight-loss-induced decrease in bone-active hormones. PMID:21786319

Intracellular Ca2+ transients in mouse soleus muscle after hindlimb unloading and reloading

NASA Technical Reports Server (NTRS)

Ingalls, C. P.; Warren, G. L.; Armstrong, R. B.; Hamilton, S. L. (Principal Investigator)

1999-01-01

The objective of this study was to determine whether altered intracellular Ca(2+) handling contributes to the specific force loss in the soleus muscle after unloading and/or subsequent reloading of mouse hindlimbs. Three groups of female ICR mice were studied: 1) unloaded mice (n = 11) that were hindlimb suspended for 14 days, 2) reloaded mice (n = 10) that were returned to their cages for 1 day after 14 days of hindlimb suspension, and 3) control mice (n = 10) that had normal cage activity. Maximum isometric tetanic force (P(o)) was determined in the soleus muscle from the left hindlimb, and resting free cytosolic Ca(2+) concentration ([Ca(2+)](i)), tetanic [Ca(2+)](i), and 4-chloro-m-cresol-induced [Ca(2+)](i) were measured in the contralateral soleus muscle by confocal laser scanning microscopy. Unloading and reloading increased resting [Ca(2+)](i) above control by 36% and 24%, respectively. Although unloading reduced P(o) and specific force by 58% and 24%, respectively, compared with control mice, there was no difference in tetanic [Ca(2+)](i). P(o), specific force, and tetanic [Ca(2+)](i) were reduced by 58%, 23%, and 23%, respectively, in the reloaded animals compared with control mice; however, tetanic [Ca(2+)](i) was not different between unloaded and reloaded mice. These data indicate that although hindlimb suspension results in disturbed intracellular Ca(2+) homeostasis, changes in tetanic [Ca(2+)](i) do not contribute to force deficits. Compared with unloading, 24 h of physiological reloading in the mouse do not result in further changes in maximal strength or tetanic [Ca(2+)](i).

Role of Oxidative Damage in Radiation-Induced Bone Loss

NASA Technical Reports Server (NTRS)

Schreurs, Ann-Sofie; Alwood, Joshua S.; Limoli, Charles L.; Globus, Ruth K.

2014-01-01

During prolonged spaceflight, astronauts are exposed to both microgravity and space radiation, and are at risk for increased skeletal fragility due to bone loss. Evidence from rodent experiments demonstrates that both microgravity and ionizing radiation can cause bone loss due to increased bone-resorbing osteoclasts and decreased bone-forming osteoblasts, although the underlying molecular mechanisms for these changes are not fully understood. We hypothesized that excess reactive oxidative species (ROS), produced by conditions that simulate spaceflight, alter the tight balance between osteoclast and osteoblast activities, leading to accelerated skeletal remodeling and culminating in bone loss. To test this, we used the MCAT mouse model; these transgenic mice over-express the human catalase gene targeted to mitochondria, the major organelle contributing free radicals. Catalase is an anti-oxidant that converts reactive species, hydrogen peroxide into water and oxygen. This animal model was selected as it displays extended lifespan, reduced cardiovascular disease and reduced central nervous system radio-sensitivity, consistent with elevated anti-oxidant activity conferred by the transgene. We reasoned that mice overexpressing catalase in mitochondria of osteoblast and osteoclast lineage cells would be protected from the bone loss caused by simulated spaceflight. Over-expression of human catalase localized to mitochondria caused various skeletal phenotypic changes compared to WT mice; this includes greater bone length, decreased cortical bone area and moment of inertia, and indications of altered microarchitecture. These findings indicate mitochondrial ROS are important for normal bone-remodeling and skeletal integrity. Catalase over-expression did not fully protect skeletal tissue from structural decrements caused by simulated spaceflight; however there was significant protection in terms of cellular oxidative damage (MDA levels) to the skeletal tissue. Furthermore, we used an array of countermeasures (Antioxidant diets and injections) to prevent the radiation-induced bone loss, although these did not prevent bone loss, analysis is ongoing to determine if these countermeasure protected radiation-induced damage to other tissues.

The estrogen-related receptors (ERRs): potential targets against bone loss.

PubMed

Zhang, Ling; Wong, Jiemin; Vanacker, Jean-Marc

2016-10-01

Bone loss and the resulting skeletal fragility is induced by several pathological or natural conditions, the most prominent of which being aging as well as the decreased levels of circulating estrogens in post-menopause females. To date, most treatments against bone loss aim at preventing excess bone resorption. We here summarize data indicating that the estrogen-related receptors (ERRs) α and γ prevent bone formation. Inhibiting these receptors may thus constitute an anabolic approach by increasing bone formation.

Characterization of bone-implant fixation using modal analysis: Application to a press-fit implant model

PubMed Central

Swider, P.; Guérin, G.; Baas, Joergen; Søballe, Kjeld; Bechtold, Joan E.

2013-01-01

Orthopaedic implant fixation is strongly dependant upon the effective mechanical properties of newly formed tissue. In this study, we evaluated the potential of modal analysis to derive viscoelastic properties of periprosthetic tissue. We hypothesized that Young's modulus and loss factor could be obtained by a combined theoretical, computational and experimental modal analysis approach. This procedure was applied to ex vivo specimens from a cylindrical experimental implant placed in cancellous bone in an unloaded press-fit configuration, obtained after a four week observation period. Four sections each from seven textured titanium implants were investigated. The first resonant frequency and loss factor were measured. Average experimentally determined loss factor was 2% (SD 0.4%) and average first resonant frequency was 2.1 KHz (SD: 50). A 2D axisymmetric finite element (FE) model identified effective Young's modulus of tissue using experimental resonant frequencies as input. Average value was 42 MPa (SD: 2.4) and no significant difference between specimens was observed. In this pilot study, the non-destructive method allowed accurate measure of dynamic loss factor and resonant frequency and derivation of effective Young's modulus. Prior to implementing this dynamic protocol for broader mechanical evaluation of experimental implant fixation, further work is needed to determine if this affects results from subsequent destructive shear push-out tests. PMID:19464687

Absence of ERRα in Female Mice Confers Resistance to Bone Loss Induced by Age or Estrogen-Deficiency

PubMed Central

Rabier, Bénédicte; Monfoulet, Laurent; Dine, Julien; Macari, Claire; Espallergues, Julie; Horard, Béatrice; Giguère, Vincent; Cohen-Solal, Martine; Chassande, Olivier; Vanacker, Jean-Marc

2009-01-01

Background ERRα is an orphan member of the nuclear hormone receptor superfamily, which acts as a transcription factor and is involved in various metabolic processes. ERRα is also highly expressed in ossification zones during mouse development as well as in human bones and cell lines. Previous data have shown that this receptor up-modulates the expression of osteopontin, which acts as an inhibitor of bone mineralization and whose absence results in resistance to ovariectomy-induced bone loss. Altogether this suggests that ERRα may negatively regulate bone mass and could impact on bone fragility that occurs in the absence of estrogens. Methods/Principal Findings In this report, we have determined the in vivo effect of ERRα on bone, using knock-out mice. Relative to wild type animals, female ERRαKO bones do not age and are resistant to bone loss induced by estrogen-withdrawal. Strikingly male ERRαKO mice are indistinguishable from their wild type counterparts, both at the unchallenged or gonadectomized state. Using primary cell cultures originating from ERRαKO bone marrow, we also show that ERRα acts as an inhibitor of osteoblast differentiation. Conclusion/Significance Down-regulating ERRα could thus be beneficial against osteoporosis. PMID:19936213

Effects of O-methylated (-)-epigallocatechin gallate (EGCG) on LPS-induced osteoclastogenesis, bone resorption, and alveolar bone loss in mice.

PubMed

Tominari, Tsukasa; Ichimaru, Ryota; Yoshinouchi, Shosei; Matsumoto, Chiho; Watanabe, Kenta; Hirata, Michiko; Grundler, Florian M W; Inada, Masaki; Miyaura, Chisato

2017-12-01

(-)-Epigallocatechin-3- O -gallate (EGCG), present in green tea, exhibits antioxidant and antiallergy effects. EGCG3″Me, a 3- O -methylated derivative of EGCG, has been reported to show similar biological functions; the inhibitory activity of EGCG3″Me in a mouse allergy model was more potent than that of EGCG, probably due to the efficiency of absorption from the intestine. However, the functional potency of these EGCGs is controversial in each disease model. We previously observed that EGCG suppressed inflammatory bone resorption and prevented alveolar bone loss in a mouse model of periodontosis. In this study, we examined the role of EGCG3″Me in bone resorption using a mouse model of periodontitis. Lipopolysaccharide (LPS)-induced osteoclast formation was suppressed by adding EGCG3″Me to cocultures of osteoblasts and bone marrow cells, and LPS-induced bone resorption was also inhibited by EGCG3″Me in calvarial organ cultures. EGCG3″Me acted on osteoblasts and suppressed prostaglandin E (PGE) production, which is critical for inflammatory bone resorption, by inhibiting the expression of COX-2 and mPGES-1, key enzymes for PGE synthesis. In osteoclast precursor macrophages, EGCG3″Me suppressed RANKL-dependent differentiation into mature osteoclasts. In a mouse model of periodontitis, LPS-induced bone resorption was suppressed by EGCG3″Me in organ culture of mouse alveolar bone, and the alveolar bone loss was further attenuated by the treatment of EGCG3″Me in the lower gingiva in vivo . EGCG3″Me may be a potential natural compound for the protection of inflammatory bone loss in periodontitis.

The Measurement Of Total Joint Loosening By X-Ray Photogrammetry

NASA Astrophysics Data System (ADS)

Lippert, Frederick G.; Veress, Sandor A.; Tiwari, Rama S.; Harrington, Richard M.

1980-07-01

Failure of total joint replacement due to loosening of the composents either between the implant and cement or between the cement and bone is emerging as a late complication with an incidence as high as 20 percent. Loosening may not only cause pain but progressive loss of support for the prosthesis with eventual structural failure. Early diagnosis is important so that revision may be carried when deterioration or pain occurs. No method is currently available which clearly establishes loosening at an early stage except surgical exploration. We have devised a method based on our in vivo photogrammetry studies of patellar tracking patterns using metallic markers placed in bone near both components of the total joint. Stereo x-rays taken with the joint loaded and unloaded are measured for relative motion between the implant and the metallic markers. Laboratory studies using prosthetic hip components mounted in plastic bone have revealed the ability of this method to detect pistoning movements as small as 80 microns. These findings were confirmed by physical measurements.

Blueberry consumption prevents loss of collagen in bone matrix and inhibits senescence pathways in osteoblastic cells

USDA-ARS?s Scientific Manuscript database

Ovariectomy (OVX)-induced bone loss has been linked to increased bone turnover and higher bone matrix collagen degradation as the result of osteoclast activation. However, the role of degraded collagen matrix in the fate of resident bone-forming cells is unclear. In this report, we show that OVX-i...

Suspension osteopenia in mice: Whole body electromagnetic field effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simske, S.J.; Luttges, M.W.

1995-08-01

Whole-body fields were tested for their efficacy in preventing the osteopenia caused by tail suspension in mice. The fields had fundamental frequencies corresponding to the upper range of predicted endogenous impact-generated frequencies (0.25--2.0 kHz) in the long bones. Three distinct whole-body EMFs were applied for 2 weeks on growing mice. Structural, geometric, and material properties of the femora, tibiae, and humeri of suspended mice were altered compared to controls. Comparison of suspended mice and mice subjected to caloric restriction indicates that the changes in caloric intake do not explain either the suspension or the field-induced effects. In agreement with pastmore » studies, rather, unloading appears to cause the suspension effects and to be addressed by the EMFs. The EMF effects on bone properties were apparently frequency dependent, with the lower two fundamental frequencies (260 and 910 Hz) altering, albeit slightly, the suspension-induced bone effects. The fields are not apparently optimized for frequency, etc., with respect to therapeutic potential; however, suspension provides a model system for further study of the in vivo effects of EMFs.« less

Suspension osteopenia in mice: whole body electromagnetic field effects.

PubMed

Simske, S J; Luttges, M W

1995-01-01

Whole-body fields were tested for their efficacy in preventing the osteopenia caused by tail suspension in mice. The fields had fundamental frequencies corresponding to the upper range of predicted endogenous impact-generated frequencies (0.25-2.0 kHz) in the long bones. Three distinct whole-body EMFs were applied for 2 weeks on growing mice. Structural, geometric, and material properties of the femora, tibiae, and humeri of suspended mice were altered compared to controls. Comparison of suspended mice and mice subjected to caloric restriction indicates that the changes in caloric intake do not explain either the suspension or the field-induced effects. In agreement with past studies, rather, unloading appears to cause the suspension effects and to be addressed by the EMFs. The EMF effects on bone properties were apparently frequency dependent, with the lower two fundamental frequencies (260 and 910 Hz) altering, albeit slightly, the suspension-induced bone effects. The fields are not apparently optimized for frequency, etc., with respect to therapeutic potential; however, suspension provides a model system for further study of the in vivo effects of EMFs.

Osteocyte-derived RANKL is a critical mediator of the increased bone resorption caused by dietary calcium deficiency

PubMed Central

Xiong, Jinhu; Piemontese, Marilina; Thostenson, Jeff D.; Weinstein, Robert S.; Manolagas, Stavros C.; O’Brien, Charles A.

2014-01-01

Parathyroid hormone (PTH) excess stimulates bone resorption. This effect is associated with increased expression of the osteoclastogenic cytokine receptor activator of nuclear factor кB ligand (RANKL) in bone. However, several different cell types, including bone marrow stromal cells, osteocytes, and T lymphocytes, express both RANKL and the PTH receptor and it is unclear whether RANKL expression by any of these cell types is required for PTH-induced bone loss. Here we have used mice lacking the RANKL gene in osteocytes to determine whether RANKL produced by this cell type is required for the bone loss caused by secondary hyperparathyroidism induced by dietary calcium deficiency in adult mice. Thirty days of dietary calcium deficiency caused bone loss in control mice, but this effect was blunted in mice lacking RANKL in osteocytes. The increase in RANKL expression in bone and the increase in osteoclast number caused by dietary calcium deficiency were also blunted in mice lacking RANKL in osteocytes. These results demonstrate that RANKL produced by osteocytes contributes to the increased bone resorption and the bone loss caused by secondary hyperparathyroidism, strengthening the evidence that osteocytes are an important target cell for hormonal control of bone remodeling. PMID:24933342

Mitochondria related peptide MOTS-c suppresses ovariectomy-induced bone loss via AMPK activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ming, Wei, E-mail: weiming@xiyi.edu.cn; Department of Pharmacology, Xi’an Medical University, Xi’an 710021; Lu, Gan, E-mail: leonming99@163.com

Therapeutic targeting bone loss has been the focus of the study in osteoporosis. The present study is intended to evaluate whether MOTS-c, a novel mitochondria related 16 aa peptide, can protect mice from ovariectomy-induced osteoporosis. After ovary removal, the mice were injected with MOTS-c at a dose of 5 mg/kg once a day for 12 weeks. Our results showed that MOTS-c treatment significantly alleviated bone loss, as determined by micro-CT examination. Mechanistically, we found that the receptor activator of nuclear factor-κB ligand (RANKL) induced osteoclast differentiation was remarkably inhibited by MOTS-c. Moreover, MOTS-c increased phosphorylated AMPK levels, and compound C, anmore » AMPK inhibitor, could partially abrogate the effects of the MOTS-c on osteoclastogenesis. Thus, our findings provide evidence that MOTS-c may exert as an inhibitor of osteoporosis via AMPK dependent inhibition of osteoclastogenesis. -- Highlights: •MOTS-c decreases OVX-induced bone loss in vivo. •MOTS-c inhibits RANKL-induced osteoclast formation. •MOTS-c inhibits RANKL-induced osteoclast-specific gene expression. •MOTS-c represses osteoclast differentiation via the activation of AMPK.« less

Effect of Korean Red Ginseng on radiation-induced bone loss in C3H/HeN mice

PubMed Central

Lee, Jin-Hee; Lee, Hae-June; Yang, Miyoung; Moon, Changjong; Kim, Jong-Choon; Bae, Chun-Sik; Jo, Sung-Kee; Jang, Jong-Sik; Kim, Sung-Ho

2013-01-01

This study investigated the effects of Korean Red Ginseng (KRG) on radiation-induced bone loss in C3H/HeN mice. C3H/HeN mice were divided into sham and irradiation (3 Gy, gamma-ray) groups. The irradiated mice were treated for 12 wk with vehicle, KRG (per os, p.o.) or KRG (intraperitoneal). Serum alkaline phosphatase (ALP), tartrate-resistant acid phosphatase, estradiol level, and biomechanical properties were measured. Tibiae were analyzed using micro-computed tomography. Treatment of KRG (p.o., 250 mg/kg of body weight/d) significantly preserved trabecular bone volume, trabecular number, structure model index, and bone mineral density of proximal tibia metaphysic, but did not alter the uterus weight of the mice. Serum ALP level was slightly reduced by KRG treatment. However, grip strength, mechanical property, and cortical bone architecture did not differ among the experimental groups. The results indicate that KRG can prevent radiation-induced bone loss in mice. PMID:24233384

A TNF receptor loop peptide mimic blocks RANK ligand–induced signaling, bone resorption, and bone loss

PubMed Central

Aoki, Kazuhiro; Saito, Hiroaki; Itzstein, Cecile; Ishiguro, Masaji; Shibata, Tatsuya; Blanque, Roland; Mian, Anower Hussain; Takahashi, Mariko; Suzuki, Yoshifumi; Yoshimatsu, Masako; Yamaguchi, Akira; Deprez, Pierre; Mollat, Patrick; Murali, Ramachandran; Ohya, Keiichi; Horne, William C.; Baron, Roland

2006-01-01

Activating receptor activator of NF-κB (RANK) and TNF receptor (TNFR) promote osteoclast differentiation. A critical ligand contact site on the TNFR is partly conserved in RANK. Surface plasmon resonance studies showed that a peptide (WP9QY) that mimics this TNFR contact site and inhibits TNF-α–induced activity bound to RANK ligand (RANKL). Changing a single residue predicted to play an important role in the interaction reduced the binding significantly. WP9QY, but not the altered control peptide, inhibited the RANKL-induced activation of RANK-dependent signaling in RAW 264.7 cells but had no effect on M-CSF–induced activation of some of the same signaling events. WP9QY but not the control peptide also prevented RANKL-induced bone resorption and osteoclastogenesis, even when TNFRs were absent or blocked. In vivo, where both RANKL and TNF-α promote osteoclastogenesis, osteoclast activity, and bone loss, WP9QY prevented the increased osteoclastogenesis and bone loss induced in mice by ovariectomy or low dietary calcium, in the latter case in both wild-type and TNFR double-knockout mice. These results suggest that a peptide that mimics a TNFR ligand contact site blocks bone resorption by interfering with recruitment and activation of osteoclasts by both RANKL and TNF. PMID:16680194

Partial gravity unloading inhibits bone healing responses in a large animal model.

PubMed

Gadomski, Benjamin C; McGilvray, Kirk C; Easley, Jeremiah T; Palmer, Ross H; Santoni, Brandon G; Puttlitz, Christian M

2014-09-22

The reduction in mechanical loading associated with space travel results in dramatic decreases in the bone mineral density (BMD) and mechanical strength of skeletal tissue resulting in increased fracture risk during spaceflight missions. Previous rodent studies have highlighted distinct bone healing differences in animals in gravitational environments versus those during spaceflight. While these data have demonstrated that microgravity has deleterious effects on fracture healing, the direct translation of these results to human skeletal repair remains problematic due to substantial differences between rodent and human bone. Thus, the objective of this study was to investigate the effects of partial gravitational unloading on long-bone fracture healing in a previously-developed large animal Haversian bone model. In vivo measurements demonstrated significantly higher orthopedic plate strains (i.e. load burden) in the Partial Unloading (PU) Group as compared to the Full Loading (FL) Group following the 28-day healing period due to inhibited healing in the reduced loading environment. DEXA BMD in the metatarsus of the PU Group decreased 17.6% (p<0.01) at the time of the ostectomy surgery. Four-point bending stiffness of the PU Group was 4.4 times lower than that of the FL Group (p<0.01), while µCT and histomorphometry demonstrated reduced periosteal callus area (p<0.05), mineralizing surface (p<0.05), mineral apposition rate (p<0.001), bone formation rate (p<0.001), and periosteal/endosteal osteoblast numbers (p<0.001/p<0.01, respectively) as well as increased periosteal osteoclast number (p<0.05). These data provide strong evidence that the mechanical environment dramatically affects the fracture healing cascade, and likely has a negative impact on Haversian system healing during spaceflight. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fluorosis increases the risk of postmenopausal osteoporosis by stimulating interferon γ.

PubMed

Lv, Yun-Gang; Kang, Li; Wu, Guangyao

2016-10-14

Estrogen deficiency in postmenopausal women frequently activates osteoclasts (OC), accelerates bone resorption, and leads to osteoporosis (OP). Previous studies have demonstrated that interferon γ (IFNγ) could increase bone resorption and may be involved in postmenopausal OP. Fluorosis also increased the risk of fractures and dental fluorosis, and fluoride may enhance osteoclast formation and induce osteoclastic bone destruction in postmenopausal women, but the underlying mechanisms are as yet unknown. Here, we show that serum fluoride and IFNγ levels are negatively correlated with bone mineral density (BMD) in postmenopausal women residing in a fluorotic area. Estrogen suppresses IFNγ, which is elevated by fluoride, playing a pivotal role in triggering bone loss in estrogen-deficient conditions. In vitro, IFNγ is inhibited by estrogen treatment and increased by fluoride in Raw264.7 cell, an osteoclast progenitor cell line. In ovariectomized (Ovx) mice, estrogen loss and IFNγ promote OC activation and subsequent bone loss in vivo. However, IFNγ deficiency prevents bone loss in Ovx mice even in fluoride conditions. Interestingly, fluoride fails to increase IFNγ expression in estrogen receptor α (ERα)-deficient conditions, but not in ERβ-deficient conditions. These findings demonstrate that fluorosis increases the bone loss in postmenopausal OP through an IFNγ-dependent mechanism. IFNγ signaling activates OC and aggravates estrogen deficiency inducing OP. Thus, stimulation of IFNγ production is a pivotal ''upstream'' mechanism by which fluoride promotes bone loss. Suppression of IFNγ levels may constitute a therapeutic approach for preventing bone loss. Copyright © 2016 Elsevier Inc. All rights reserved.

Cancer treatment-induced bone loss in premenopausal women: a need for therapeutic intervention?

PubMed

Hadji, P; Gnant, M; Body, J J; Bundred, N J; Brufsky, A; Coleman, R E; Guise, T A; Lipton, A; Aapro, M S

2012-10-01

Current clinical treatment guidelines recommend cytotoxic chemotherapy, endocrine therapy, or both (with targeted therapy if indicated) for premenopausal women with early-stage breast cancer, depending on the biologic characteristics of the primary tumor. Some of these therapies can induce premature menopause or are specifically designed to suppress ovarian function and reduce circulating estrogen levels. In addition to bone loss associated with low estrogen levels, cytotoxic chemotherapy may have a direct negative effect on bone metabolism. As a result, cancer treatment-induced bone loss poses a significant threat to bone health in premenopausal women with breast cancer. Clinical trials of antiresorptive therapies, such as bisphosphonates, have demonstrated the ability to slow or prevent bone loss in this setting. Current fracture risk assessment tools are based on data from healthy postmenopausal women and do not adequately address the risks associated with breast cancer therapy, especially in younger premenopausal women. We therefore recommend that all premenopausal women with breast cancer be informed about the potential risk of bone loss prior to beginning anticancer therapy. Women who experience amenorrhea should have bone mineral density assessed by dual-energy X-ray absorptiometry and receive regular follow-up to monitor bone health. Regular exercise and daily calcium and vitamin D supplementation are recommended. Women with a Z-score <-2.0 or Z-score ≤-1.0 and/or a 5-10% annual decrease in bone mineral density should be considered for bisphosphonate therapy in addition to calcium and vitamin D supplements. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of Polymethoxyflavonoids on Bone Loss Induced by Estrogen Deficiency and by LPS-Dependent Inflammation in Mice.

PubMed

Matsumoto, Shigeru; Tominari, Tsukasa; Matsumoto, Chiho; Yoshinouchi, Shosei; Ichimaru, Ryota; Watanabe, Kenta; Hirata, Michiko; Grundler, Florian M W; Miyaura, Chisato; Inada, Masaki

2018-01-20

Polymethoxyflavonoids (PMFs) are a family of the natural compounds that mainly compise nobiletin, tangeretin, heptamethoxyflavone (HMF), and tetramethoxyflavone (TMF) in citrus fruits. PMFs have shown various biological functions, including anti-oxidative effects. We previously showed that nobiletin, tangeretin, and HMF all inhibited interleukin (IL)-1-mediated osteoclast differentiation via the inhibition of prostaglandin E2 synthesis. In this study, we created an original mixture of PMFs (nobiletin, tangeretin, HMF, and TMF) and examined whether or not PMFs exhibit co-operative inhibitory effects on osteoclastogenesis and bone resorption. In a coculture of bone marrow cells and osteoblasts, PMFs dose-dependently inhibited IL-1-induced osteoclast differentiation and bone resorption. The optimum concentration of PMFs was lower than that of nobiletin alone in the suppression of osteoclast differentiation, suggesting that the potency of PMFs was stronger than that of nobiletin in vitro. The oral administration of PMFs recovered the femoral bone loss induced by estrogen deficiency in ovariectomized mice. We further tested the effects of PMFs on lipopolysaccharide-induced bone resorption in mouse alveolar bone. In an ex vivo experimental model for periodontitis, PMFs significantly suppressed the bone-resorbing activity in organ cultures of mouse alveolar bone. These results indicate that a mixture of purified nobiletin, tangeretin, HMF, and TMF exhibits a co-operative inhibitory effect for the protection against bone loss in a mouse model of bone disease, suggesting that PMFs may be potential candidates for the prevention of bone resorption diseases, such as osteoporosis and periodontitis.

Osteoporosis affects both post-yield microdamage accumulation and plasticity degradation in vertebra of ovariectomized rats

NASA Astrophysics Data System (ADS)

Li, Siwei; Niu, Guodong; Dong, Neil X.; Wang, Xiaodu; Liu, Zhongjun; Song, Chunli; Leng, Huijie

2017-04-01

Estrogen withdrawal in postmenopausal women increases bone loss and bone fragility in the vertebra. Bone loss with osteoporosis not only reduces bone mineral density (BMD), but actually alters bone quality, which can be comprehensively represented by bone post-yield behaviors. This study aimed to provide some information as to how osteoporosis induced by estrogen depletion could influence the evolution of post-yield microdamage accumulation and plastic deformation in vertebral bodies. This study also tried to reveal the part of the mechanisms of how estrogen deficiency-induced osteoporosis would increase the bone fracture risk. A rat bilateral ovariectomy (OVX) model was used to induce osteoporosis. Progressive cyclic compression loading was developed for vertebra testing to elucidate the post-yield behaviors. BMD, bone volume fraction, stiffness degradation, and plastic deformation evolution were compared among rats raised for 5 weeks (ovx5w and sham5w groups) and 35 weeks (ovx35w and sham35w groups) after sham surgery and OVX. The results showed that a higher bone loss in vertebral bodies corresponded to lower stiffness and higher plastic deformation. Thus, osteoporosis could increase the vertebral fracture risk probably through microdamage accumulation and plastic deforming degradation.

Missense Mutations in LRP5 Associated with High Bone Mass Protect the Mouse Skeleton from Disuse- and Ovariectomy-Induced Osteopenia.

PubMed

Niziolek, Paul J; Bullock, Whitney; Warman, Matthew L; Robling, Alexander G

2015-01-01

The low density lipoprotein receptor-related protein-5 (LRP5), a co-receptor in the Wnt signaling pathway, modulates bone mass in humans and in mice. Lrp5 knock-out mice have severely impaired responsiveness to mechanical stimulation whereas Lrp5 gain-of-function knock-in and transgenic mice have enhanced responsiveness to mechanical stimulation. Those observations highlight the importance of Lrp5 protein in bone cell mechanotransduction. It is unclear if and how high bone mass-causing (HBM) point mutations in Lrp5 alter the bone-wasting effects of mechanical disuse. To address this issue we explored the skeletal effects of mechanical disuse using two models, tail suspension and Botulinum toxin-induced muscle paralysis, in two different Lrp5 HBM knock-in mouse models. A separate experiment employing estrogen withdrawal-induced bone loss by ovariectomy was also conducted as a control. Both disuse stimuli induced significant bone loss in WT mice, but Lrp5 A214V and G171V were partially or fully protected from the bone loss that normally results from disuse. Trabecular bone parameters among HBM mice were significantly affected by disuse in both models, but these data are consistent with DEXA data showing a failure to continue growing in HBM mice, rather than a loss of pre-existing bone. Ovariectomy in Lrp5 HBM mice resulted in similar protection from catabolism as was observed for the disuse experiments. In conclusion, the Lrp5 HBM alleles offer significant protection from the resorptive effects of disuse and from estrogen withdrawal, and consequently, present a potential mechanism to mimic with pharmaceutical intervention to protect against various bone-wasting stimuli.

Protective Effects of Vildagliptin against Pioglitazone-Induced Bone Loss in Type 2 Diabetic Rats

PubMed Central

Kwak, Kyung Min; Kim, Ju-Young; Yu, Seung Hee; Lee, Sihoon; Kim, Yeun Sun; Park, Ie Byung; Kim, Kwang-Won; Lee, Kiyoung

2016-01-01

Long-term use of thiazolidinediones (TZDs) is associated with bone loss and an increased risk of fracture in patients with type 2 diabetes (T2DM). Incretin-based drugs (glucagon-like peptide-1 (GLP-1) agonists and dipeptidylpeptidase-4 (DPP-4) inhibitors) have several benefits in many systems in addition to glycemic control. In a previous study, we reported that exendin-4 might increase bone mineral density (BMD) by decreasing the expression of SOST/sclerostin in osteocytes in a T2DM animal model. In this study, we investigated the effects of a DPP-4 inhibitor on TZD-induced bone loss in a T2DM animal model. We randomly divided 12-week-old male Zucker Diabetic Fatty (ZDF) rats into four groups; control, vildagliptin, pioglitazone, and vildagliptin and pioglitazone combination. Animals in each group received the respective treatments for 5 weeks. We performed an intraperitoneal glucose tolerance test (IPGTT) before and after treatment. BMD and the trabecular micro-architecture were measured by DEXA and micro CT, respectively, at the end of the treatment. The circulating levels of active GLP-1, bone turnover markers, and sclerostin were assayed. Vildagliptin treatment significantly increased BMD and trabecular bone volume. The combination therapy restored BMD, trabecular bone volume, and trabecular bone thickness that were decreased by pioglitazone. The levels of the bone formation marker, osteocalcin, decreased and that of the bone resorption marker, tartrate-resistant acid phosphatase (TRAP) 5b increased in the pioglitazone group. These biomarkers were ameliorated and the pioglitazone-induced increase in sclerostin level was lowered to control values by the addition of vildagliptin. In conclusion, our results indicate that orally administered vildagliptin demonstrated a protective effect on pioglitazone-induced bone loss in a type 2 diabetic rat model. PMID:27997588

Protective Effects of Vildagliptin against Pioglitazone-Induced Bone Loss in Type 2 Diabetic Rats.

PubMed

Eom, Young Sil; Gwon, A-Ryeong; Kwak, Kyung Min; Kim, Ju-Young; Yu, Seung Hee; Lee, Sihoon; Kim, Yeun Sun; Park, Ie Byung; Kim, Kwang-Won; Lee, Kiyoung; Kim, Byung-Joon

2016-01-01

Long-term use of thiazolidinediones (TZDs) is associated with bone loss and an increased risk of fracture in patients with type 2 diabetes (T2DM). Incretin-based drugs (glucagon-like peptide-1 (GLP-1) agonists and dipeptidylpeptidase-4 (DPP-4) inhibitors) have several benefits in many systems in addition to glycemic control. In a previous study, we reported that exendin-4 might increase bone mineral density (BMD) by decreasing the expression of SOST/sclerostin in osteocytes in a T2DM animal model. In this study, we investigated the effects of a DPP-4 inhibitor on TZD-induced bone loss in a T2DM animal model. We randomly divided 12-week-old male Zucker Diabetic Fatty (ZDF) rats into four groups; control, vildagliptin, pioglitazone, and vildagliptin and pioglitazone combination. Animals in each group received the respective treatments for 5 weeks. We performed an intraperitoneal glucose tolerance test (IPGTT) before and after treatment. BMD and the trabecular micro-architecture were measured by DEXA and micro CT, respectively, at the end of the treatment. The circulating levels of active GLP-1, bone turnover markers, and sclerostin were assayed. Vildagliptin treatment significantly increased BMD and trabecular bone volume. The combination therapy restored BMD, trabecular bone volume, and trabecular bone thickness that were decreased by pioglitazone. The levels of the bone formation marker, osteocalcin, decreased and that of the bone resorption marker, tartrate-resistant acid phosphatase (TRAP) 5b increased in the pioglitazone group. These biomarkers were ameliorated and the pioglitazone-induced increase in sclerostin level was lowered to control values by the addition of vildagliptin. In conclusion, our results indicate that orally administered vildagliptin demonstrated a protective effect on pioglitazone-induced bone loss in a type 2 diabetic rat model.

Green tea polyphenols mitigate bone loss of female rats in a chronic inflammation-induced bone loss model

USDA-ARS?s Scientific Manuscript database

The purpose of this study was to explore bioavailability, efficacy, and molecular mechanisms of green tea polyphenols (GTP) related to preventing bone loss in rats with chronic inflammation. A 2 (placebo vs. lipopolysaccharide, LPS) × 2 (no GTP vs. 0.5% GTP in drinking water) factorial design using ...

Effect of methylprednisolone on bone mineral density in rats with ovariectomy-induced bone loss and suppressed endogenous adrenaline levels by metyrosine

PubMed Central

Yilmaz, Mehmet; Isaoglu, Unal; Uslu, Turan; Yildirim, Kadir; Seven, Bedri; Akcay, Fatih; Hacimuftuoglu, Ahmet

2013-01-01

Objectives: In this study, effect of methylprednisolone on bone mineral density (BMD) was investigated in rats with overiectomy induced bone lose and suppressed endogenous adrenalin levels, and compared to alendronate. Materials and Methods: Severity of bone loss in the examined material (femur bones) was evaluated by BMD measurement. Results: The group with the highest BMD value was metyrosinemetyrosine + methylprednisolone combination (0.151 g/cm2), while that with the lowest BMD was methylprednisolone (0.123 g/cm2). Alendronate was effective only when used alone in ovariectomized rats (0.144 g/cm2), but not when used in combination with methylprednisolone (0.124 g/cm2). In the ovariectomized rat group which received only metyrosine, BMD value was statistically indifferent from ovariectomized control group. Conclusions: Methylprednisolone protected bone loss in rats with suppressed adrenaline levels because of metyrosinemetyrosine. PMID:24014908

Potential Effects of Phytoestrogen Genistein in Modulating Acute Methotrexate Chemotherapy-Induced Osteoclastogenesis and Bone Damage in Rats

PubMed Central

King, Tristan J.; Shandala, Tetyana; Lee, Alice M.; Foster, Bruce K.; Chen, Ke-Ming; Howe, Peter R.; Xian, Cory J.

2015-01-01

Chemotherapy-induced bone damage is a frequent side effect which causes diminished bone mineral density and fracture in childhood cancer sufferers and survivors. The intensified use of anti-metabolite methotrexate (MTX) and other cytotoxic drugs has led to the need for a mechanistic understanding of chemotherapy-induced bone loss and for the development of protective treatments. Using a young rat MTX-induced bone loss model, we investigated potential bone protective effects of phytoestrogen genistein. Oral gavages of genistein (20 mg/kg) were administered daily, for seven days before, five days during, and three days after five once-daily injections (sc) of MTX (0.75 mg/kg). MTX treatment reduced body weight gain and tibial metaphyseal trabecular bone volume (p < 0.001), increased osteoclast density on the trabecular bone surface (p < 0.05), and increased the bone marrow adipocyte number in lower metaphyseal bone (p < 0.001). Genistein supplementation preserved body weight gain (p < 0.05) and inhibited ex vivo osteoclast formation of bone marrow cells from MTX-treated rats (p < 0.001). However, MTX-induced changes in bone volume, trabecular architecture, metaphyseal mRNA expression of pro-osteoclastogenic cytokines, and marrow adiposity were not significantly affected by the co-administration of genistein. This study suggests that genistein may suppress MTX-induced osteoclastogenesis; however, further studies are required to examine its potential in protecting against MTX chemotherapy-induced bone damage. PMID:26258775

The relationship between exercise-induced muscle fatigue, arterial blood flow and muscle perfusion after 56 days local muscle unloading.

PubMed

Weber, Tobias; Ducos, Michel; Mulder, Edwin; Beijer, Åsa; Herrera, Frankyn; Zange, Jochen; Degens, Hans; Bloch, Wilhelm; Rittweger, Jörn

2014-05-01

In the light of the dynamic nature of habitual plantar flexor activity, we utilized an incremental isokinetic exercise test (IIET) to assess the work-related power deficit (WoRPD) as a measure for exercise-induced muscle fatigue before and after prolonged calf muscle unloading and in relation to arterial blood flow and muscle perfusion. Eleven male subjects (31 ± 6 years) wore the HEPHAISTOS unloading orthosis unilaterally for 56 days. It allows habitual ambulation while greatly reducing plantar flexor activity and torque production. Endpoint measurements encompassed arterial blood flow, measured in the femoral artery using Doppler ultrasound, oxygenation of the soleus muscle assessed by near-infrared spectroscopy, lactate concentrations determined in capillary blood and muscle activity using soleus muscle surface electromyography. Furthermore, soleus muscle biopsies were taken to investigate morphological muscle changes. After the intervention, maximal isokinetic torque was reduced by 23·4 ± 8·2% (P<0·001) and soleus fibre size was reduced by 8·5 ± 13% (P = 0·016). However, WoRPD remained unaffected as indicated by an unchanged loss of relative plantar flexor power between pre- and postexperiments (P = 0·88). Blood flow, tissue oxygenation, lactate concentrations and EMG median frequency kinematics during the exercise test were comparable before and after the intervention, whereas the increase of RMS in response to IIET was less following the intervention (P = 0·03). In conclusion, following submaximal isokinetic muscle work exercise-induced muscle fatigue is unaffected after prolonged local muscle unloading. The observation that arterial blood flow was maintained may underlie the unchanged fatigability. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Estrogen-Related Receptors and the control of bone cell fate.

PubMed

Carnesecchi, Julie; Vanacker, Jean-Marc

2016-09-05

Bone loss is naturally occurring in aging males and females and exacerbated in the latter after menopause, altogether leading to cumulative skeleton fragility and increased fracture risk. Two types of therapeutic strategies can be envisioned to counteract age- or menopause-associated bone loss, aiming at either reducing bone resorption exerted by osteoclasts or, alternatively, promoting bone formation by osteoblasts. We here summarize data suggesting that inhibition of the Estrogen-Related Receptors α and/or γ could promote bone formation and compensate for bone loss induced by ageing or estrogen-deficiency. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Dried Plum Protects From Radiation-Induced Bone Loss by Attenuating Pro-Osteoclastic and Oxidative Stress Responses

NASA Technical Reports Server (NTRS)

Globus, Ruth

2015-01-01

Future space explorations beyond the earths magnetosphere will increase human exposure to space radiation and associated risks to skeletal health. We hypothesize that oxidative stress resulting from radiation exposure plays a major role in progressive bone loss and dysfunction in associated tissue. In animal studies, increased free radical formation is associated with pathological changes in bone structure, enhanced bone resorption, reduced bone formation and decreased bone mineral density, which can lead to skeletal fragility. Our long-term goals are to define the mechanisms and risk of bone loss in the spaceflight environment and to facilitate the development of effective countermeasures. We had previously reported that exposure to low or high-LET radiation correlates with an acute increase in the expression of pro-osteoclastic and oxidative stress genes in bone during the early response to radiation followed by pathological changes in skeletal structure. We then conducted systematic screening for potential countermeasures against bone loss where we tested the ability of various antioxidants to mitigate the radiation-induced increase in expression of these markers. For the screen, 16-week old C57Bl6J mice were treated with a dietary antioxidant cocktail, injectable DHLA or a dried plum-enriched diet (DP). Mice were then exposed to 2Gy 137Cs radiation and one day later, marrow cells were collected and the relevant genes analyzed for expression levels. Among the candidate countermeasures tested, DP was most effective in reducing the expression of genes associated with bone loss. Furthermore, analysis of skeletal structure by microcomputed tomography (microCT) revealed that DP also prevents the radiation-induced deterioration in skeletal microarchitecture as indicated by parameters such as percent bone volume (BVTV), trabecular spacing and trabecular number. We also found that DP has similar protective effects on skeletal structure in a follow-up study using 1 Gy of sequential proton and iron, radiation species relevant to spaceflight. When cultured ex vivo under osteogenic conditions, bone marrow-derived cells from DP-fed animals exhibited increased colony numbers compared to control diet-fed animals. These findings suggest that DP exerts pro-osteogenic effects apart from its previously demonstrated anti-resorptive action, which may be one of the mechanisms underlying its radioprotective effect on bone. In conclusion, a diet enriched in certain types of antioxidants may be useful as an intervention for radiation-induced bone loss.

Arthritogenic alphaviral infection perturbs osteoblast function and triggers pathologic bone loss

PubMed Central

Chen, Weiqiang; Foo, Suan-Sin; Rulli, Nestor E.; Taylor, Adam; Sheng, Kuo-Ching; Herrero, Lara J.; Herring, Belinda L.; Lidbury, Brett A.; Li, Rachel W.; Walsh, Nicole C.; Sims, Natalie A.; Smith, Paul N.; Mahalingam, Suresh

2014-01-01

Arthritogenic alphaviruses including Ross River virus (RRV), Sindbis virus, and chikungunya virus cause worldwide outbreaks of musculoskeletal disease. The ability of alphaviruses to induce bone pathologies remains poorly defined. Here we show that primary human osteoblasts (hOBs) can be productively infected by RRV. RRV-infected hOBs produced high levels of inflammatory cytokine including IL-6. The RANKL/OPG ratio was disrupted in the synovial fluid of RRV patients, and this was accompanied by an increase in serum Tartrate-resistant acid phosphatase 5b (TRAP5b) levels. Infection of bone cells with RRV was validated using an established RRV murine model. In wild-type mice, infectious virus was detected in the femur, tibia, patella, and foot, together with reduced bone volume in the tibial epiphysis and vertebrae detected by microcomputed tomographic (µCT) analysis. The RANKL/OPG ratio was also disrupted in mice infected with RRV; both this effect and the bone loss were blocked by treatment with an IL-6 neutralizing antibody. Collectively, these findings provide previously unidentified evidence that alphavirus infection induces bone loss and that OBs are capable of producing proinflammatory mediators during alphavirus-induced arthralgia. The perturbed RANKL/OPG ratio in RRV-infected OBs may therefore contribute to bone loss in alphavirus infection. PMID:24733914

Formononetin, an isoflavone, activates AMP-activated protein kinase/β-catenin signalling to inhibit adipogenesis and rescues C57BL/6 mice from high-fat diet-induced obesity and bone loss.

PubMed

Gautam, Jyoti; Khedgikar, Vikram; Kushwaha, Priyanka; Choudhary, Dharmendra; Nagar, Geet Kumar; Dev, Kapil; Dixit, Preety; Singh, Divya; Maurya, Rakesh; Trivedi, Ritu

2017-03-01

Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT's rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.

Spinal Health during Unloading and Reloading Associated with Spaceflight

PubMed Central

Green, David A.; Scott, Jonathan P. R.

2018-01-01

Spinal elongation and back pain are recognized effects of exposure to microgravity, however, spinal health has received relatively little attention. This changed with the report of an increased risk of post-flight intervertebral disc (IVD) herniation and subsequent identification of spinal pathophysiology in some astronauts post-flight. Ground-based analogs, particularly bed rest, suggest that a loss of spinal curvature and IVD swelling may be factors contributing to unloading-induced spinal elongation. In flight, trunk muscle atrophy, in particular multifidus, may precipitate lumbar curvature loss and reduced spinal stability, but in-flight (ultrasound) and pre- and post-flight (MRI) imaging have yet to detect significant IVD changes. Current International Space Station missions involve short periods of moderate-to-high spinal (axial) loading during running and resistance exercise, superimposed upon a background of prolonged unloading (microgravity). Axial loading acting on a dysfunctional spine, weakened by anatomical changes and local muscle atrophy, might increase the risk of damage/injury. Alternatively, regular loading may be beneficial. Spinal pathology has been identified in-flight, but there are few contemporary reports of in-flight back injury and no recent studies of post-flight back injury incidence. Accurate routine in-flight stature measurements, in- and post-flight imaging, and tracking of pain and injury (herniation) for at least 2 years post-flight is thus warranted. These should be complemented by ground-based studies, in particular hyper buoyancy floatation (HBF) a novel analog of spinal unloading, in order to elucidate the mechanisms and risk of spinal injury, and to evaluate countermeasures for exploration where injury could be mission critical. PMID:29403389

Spinal Health during Unloading and Reloading Associated with Spaceflight.

PubMed

Green, David A; Scott, Jonathan P R

2017-01-01

Spinal elongation and back pain are recognized effects of exposure to microgravity, however, spinal health has received relatively little attention. This changed with the report of an increased risk of post-flight intervertebral disc (IVD) herniation and subsequent identification of spinal pathophysiology in some astronauts post-flight. Ground-based analogs, particularly bed rest, suggest that a loss of spinal curvature and IVD swelling may be factors contributing to unloading-induced spinal elongation. In flight, trunk muscle atrophy, in particular multifidus , may precipitate lumbar curvature loss and reduced spinal stability, but in-flight (ultrasound) and pre- and post-flight (MRI) imaging have yet to detect significant IVD changes. Current International Space Station missions involve short periods of moderate-to-high spinal (axial) loading during running and resistance exercise, superimposed upon a background of prolonged unloading (microgravity). Axial loading acting on a dysfunctional spine, weakened by anatomical changes and local muscle atrophy, might increase the risk of damage/injury. Alternatively, regular loading may be beneficial. Spinal pathology has been identified in-flight, but there are few contemporary reports of in-flight back injury and no recent studies of post-flight back injury incidence. Accurate routine in-flight stature measurements, in- and post-flight imaging, and tracking of pain and injury (herniation) for at least 2 years post-flight is thus warranted. These should be complemented by ground-based studies, in particular hyper buoyancy floatation (HBF) a novel analog of spinal unloading, in order to elucidate the mechanisms and risk of spinal injury, and to evaluate countermeasures for exploration where injury could be mission critical.

Orthopaedic wear particle-induced bone loss and exogenous macrophage infiltration is mitigated by local infusion of NF-κB decoy oligodeoxynucleotide.

PubMed

Lin, Tzuhua; Pajarinen, Jukka; Nabeshima, Akira; Córdova, Luis A; Loi, Florence; Gibon, Emmanuel; Lu, Laura; Nathan, Karthik; Jämsen, Eemeli; Yao, Zhenyu; Goodman, Stuart B

2017-11-01

Excessive production of wear particles from total joint replacements induces chronic inflammation, macrophage infiltration, and consequent bone loss (periprosthetic osteolysis). This inflammation and bone remodeling are critically regulated by the transcription factor NF-κB. We previously demonstrated that inhibition of NF-κB signaling by using the decoy oligodeoxynucleotide (ODN) mitigates polyethylene wear particle-induced bone loss using in vitro and in vivo models. However, the mechanisms of NF-κB decoy ODN action, and in particular its impact on systemic macrophage recruitment, remain unknown. In the current study, this systemic macrophage infiltration was examined in our established murine femoral continuous particle infusion model. RAW264.7 murine macrophages expressing a luciferase reporter gene were injected into the systemic circulation. Quantification of bioluminescence showed that NF-κB decoy ODN reduced the homing of these reporter macrophages into the distal femurs exposed to continuous particle delivery. Particle-induced reduction in bone mineral density at the distal diaphysis of the femur was also mitigated by infusion of decoy ODN. Histological staining showed that the decoy ODN infusion decreased osteoclast and macrophage numbers, but had no significant effects on osteoblasts. Local infusion of NF-κB decoy ODN reduced systemic macrophage infiltration and mitigated particle-induced bone loss, thus providing a potential strategy to treat periprosthetic osteolysis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3169-3175, 2017. © 2017 Wiley Periodicals, Inc.

Effect of Local Vibration and Passive Exercise on the Hormones and Neurotransmitters of Hypothalamic-Pituitary-Adrenal Axis in Hindlimb Unloading Rats

NASA Astrophysics Data System (ADS)

Luan, Huiqin; Huang, Yunfei; Li, Jian; Sun, Lianwen; Fan, Yubo

2018-04-01

Astronauts are severely affected by spaceflight-induced bone loss. Mechanical stimulation through exercise inhibits bone resorption and improves bone formation. Exercise and vibration can prevent the degeneration of the musculoskeletal system in tail-suspended rats, and long-term exercise stress will affect endocrine and immune systems that are prone to fatigue. However, the mechanisms through which exercise and vibration affect the endocrine system remain unknown. This study mainly aimed to investigate the changes in the contents of endocrine axis-related hormones and the effects of local vibration and passive exercise on hypothalamic-pituitary-adrenal (HPA) axis-related hormones in tail-suspended rats. A total of 32 Sprague-Dawley rats were randomly distributed into four groups (n = 8 per group): tail suspension (TS), TS + 35Hz vibration, TS + passive exercise, and control. The rats were placed on a passive exercise and local vibration regimen for 21 days. On day 22 of the experiment, the contents of corticotrophin-releasing hormone, adrenocorticotropic hormone, cortisol, and 5-hydroxytryptamine in the rats were quantified with kits in accordance with the manufacturer's instructions. Histomorphometry was applied to evaluate histological changes in the hypothalamus. Results showed that 35Hz local vibration cannot cause rats to remain in a stressed state and that it might not inhibit the function of the HPA axis. Therefore, we speculate that this local vibration intensity can protect the function of the HPA axis and helps tail-suspended rats to transition from stressed to adaptive state.

Alpha-1 antitrypsin gene therapy prevented bone loss in ovariectomy induced osteoporosis mouse model

USDA-ARS?s Scientific Manuscript database

Osteoporosis is a major healthcare burden affecting mostly postmenopausal women characterized by compromised bone strength and increased risk of fragility fracture. Although pathogenesis of this disease is complex, elevated proinflammatory cytokine production is clearly involved in bone loss at meno...

Skeletal Micro-RNA Responses to Simulated Weightlessness

NASA Technical Reports Server (NTRS)

Thomas, Nicholas J.; Choi, Catherine Y.; Alwood, Joshua S.

2016-01-01

Astronauts lose bone structure during long-duration spaceflight. These changes are due, in part, to insufficient bone formation by the osteoblast cells. Little is known about the role that small (approximately 22 nucleotides), non-coding micro-RNAs (miRNAs) play in the osteoblast response to microgravity. We hypothesize that osteoblast-lineage cells alter their miRNA status during microgravity exposure, contributing to impaired bone formation during weightlessness. To simulate weightlessness, female mice (C57BL/6, Charles River, 10 weeks of age, n = 7) were hindlimb unloaded up to 12 days. Age-matched and normally ambulating mice served as controls (n=7). To assess the expression of miRNAs in skeletal tissue, the tibia was collected ex vivo and cleaned of soft-tissue and marrow. Total RNA was collected from tibial bone and relative abundance was measured for miRNAs of interest using quantitative real time PCR array looking at 372 unique and well-characterized mature miRNAs using the delta-delta Ct method. Transcripts of interest were normalized to an average of 6 reference RNAs. Preliminary results show that hindlimb unloading decreased the expression of 14 miRNAs to less than 0.5 times that of the control levels and increased the expression of 5 miRNAs relative to the control mice between 1.2-1.5-fold (p less than 0.05, respectively). Using the miRSystem we assessed overlapping target genes predicted to be regulated by multiple members of the 19 differentially expressed miRNAs as well as in silico predicted targets of our individual miRNAs. Our miRsystem results indicated that a number of our differentially expressed miRNAs were regulators of genes related to the Wnt-Beta Catenin pathway-a known regulator of bone health-and, interestingly, the estrogen-mediated cell-cycle regulation pathway, which may indicate that simulated weightlessness modulated systemic hormonal levels or hormonal transduction that additionally contributed to bone loss. We plan to follow up these findings by measuring gene expression of miRNA-regulated genes within these two pathways with the aim of furthering our understanding of the function of miRNAs in the skeletal response to spaceflight.

Protective effect of salidroside against bone loss via hypoxia-inducible factor-1α pathway-induced angiogenesis

PubMed Central

Li, Ling; Qu, Ye; Jin, Xin; Guo, Xiao Qin; Wang, Yue; Qi, Lin; Yang, Jing; Zhang, Peng; Li, Ling Zhi

2016-01-01

Hypoxia-inducible factor (HIF)-1α plays a critical role in coupling angiogenesis with osteogenesis during bone development and regeneration. Salidroside (SAL) has shown anti-hypoxic effects in vitro and in vivo. However, the possible roles of SAL in the prevention of hypoxia-induced osteoporosis have remained unknown. Two osteoblast cell lines, MG-63 and ROB, were employed to evaluate the effects of SAL on cell viability, apoptosis, differentiation and mineralization in vitro. Rats subjected to ovariectomy-induced bone loss were treated with SAL in vivo. Our results showed that pre-treatment with SAL markedly attenuated the hypoxia-induced reductions in cell viability, apoptosis, differentiation and mineralization. SAL down-regulated HIF-1α expression and inhibited its translocation; however, SAL increased its transcriptional activity and, consequently, up-regulated vascular endothelial growth factor (VEGF). In vivo studies further demonstrated that SAL caused decreases in the mineral, alkaline phosphatase (ALP), and BGP concentrations in the blood of ovariectomized (OVX) rats. Moreover, SAL improved the trabecular bone microarchitecture and increased bone mineral density in the distal femur. Additionally, SAL administration partially ameliorated this hypoxia via the HIF-1α-VEGF signalling pathway. Our results indicate that SAL prevents bone loss by enhancing angiogenesis and osteogenesis and that these effects are associated with the activation of HIF-1α signalling. PMID:27558909

Transgenic Mouse Model for Reducing Oxidative Damage in Bone

NASA Technical Reports Server (NTRS)

Schreurs, Ann-Sofie; Torres, S.; Truong, T.; Moyer, E. L.; Kumar, A.; Tahimic, Candice C. G.; Alwood, J. S.; Limoli, C. L.; Globus, R. K.

2016-01-01

Bone loss can occur due to many challenges such age, radiation, microgravity, and Reactive Oxygen Species (ROS) play a critical role in bone resorption by osteoclasts (Bartell et al. 2014). We hypothesize that suppression of excess ROS in skeletal cells, both osteoblasts and osteoclasts, regulates skeletal growth and remodeling. To test our hypothesis, we used transgenic mCAT mice which overexpress the human anti-oxidant catalase gene targeted to the mitochondria, the main site for endogenous ROS production. mCAT mice have a longer life-span than wildtype controls and have been used to study various age-related disorders. To stimulate remodeling, 16 week old mCAT mice or wildtype mice were exposed to treatment (hindlimb-unloading and total body-irradiation) or sham treatment conditions (control). Tissues were harvested 2 weeks later for skeletal analysis (microcomputed tomography), biochemical analysis (gene expression and oxidative damage measurements), and ex vivo bone marrow derived cell culture (osteoblastogenesis and osteoclastogenesis). mCAT mice expressed the transgene and displayed elevated catalase activity in skeletal tissue and marrow-derived osteoblasts and osteoclasts grown ex vivo. In addition, when challenged with treatment, bone tissues from wildtype mice showed elevated levels of malondialdehyde (MDA), indicating oxidative damage) whereas mCAT mice did not. Correlation analysis revealed that increased catalase activity significantly correlated with decreased MDA levels and that increased oxidative damage correlated with decreased percent bone volume (BVTV). In addition, ex-vivo cultured osteoblast colony growth correlated with catalase activity in the osteoblasts. Thus, we showed that these transgenic mice can be used as a model to study the relationship between markers of oxidative damage and skeletal properties. mCAT mice displayed reduced BVTV and trabecular number relative to wildtype mice, as well as increased structural model index in the cancellous tibia. Treatment caused bone loss in wildtype mice, as expected. Treatment also caused deficits in microarchitecture of mCAT mice, although less severe than wildtype mice in some parameters (percent bone volume, structural model index and cortical area). In conclusion, our results indicate that endogenous ROS signaling in both osteoblast and osteoclast lineage cells contributes to skeletal growth and remodeling, and quenching oxidative damage could play a role in bone loss prevention.

Antiosteoclastic activity of milk thistle extract after ovariectomy to suppress estrogen deficiency-induced osteoporosis.

PubMed

Kim, Jung-Lye; Kim, Yun-Ho; Kang, Min-Kyung; Gong, Ju-Hyun; Han, Seoung-Jun; Kang, Young-Hee

2013-01-01

Bone integrity abnormality and imbalance between bone formation by osteoblasts and bone resorption by osteoclasts are known to result in metabolic bone diseases such as osteoporosis. Silymarin-rich milk thistle extract (MTE) and its component silibinin enhanced alkaline phosphatase activity of osteoblasts but reduced tartrate-resistant acid phosphatase (TRAP) activity of osteoclasts. The osteoprotective effects of MTE were comparable to those of estrogenic isoflavone. Low-dose combination of MTE and isoflavone had a pharmacological synergy that may be useful for osteogenic activity. This study attempted to reveal the suppressive effects of MTE on bone loss. C57BL/6 female mice were ovariectomized (OVX) as a model for postmenopausal osteopenia and orally administered 10 mg/kg MTE or silibinin for 8 weeks. The sham-operated mice served as estrogen controls. The treatment of ovariectomized mice with nontoxic MTE and silibinin improved femoral bone mineral density and serum receptor activator of nuclear factor- κB ligand/osteoprotegerin ratio, an index of osteoclastogenic stimulus. In addition, the administration of MTE or silibinin inhibited femoral bone loss induced by ovariectomy and suppressed femoral TRAP activity and cathepsin K induction responsible for osteoclastogenesis and bone resorption. Collectively, oral dosage of MTE containing silibinin in the preclinical setting is effective in preventing estrogen deficiency-induced bone loss.

Antiosteoclastic Activity of Milk Thistle Extract after Ovariectomy to Suppress Estrogen Deficiency-Induced Osteoporosis

PubMed Central

Kim, Jung-Lye; Kim, Yun-Ho; Kang, Min-Kyung; Gong, Ju-Hyun; Han, Seoung-Jun; Kang, Young-Hee

2013-01-01

Bone integrity abnormality and imbalance between bone formation by osteoblasts and bone resorption by osteoclasts are known to result in metabolic bone diseases such as osteoporosis. Silymarin-rich milk thistle extract (MTE) and its component silibinin enhanced alkaline phosphatase activity of osteoblasts but reduced tartrate-resistant acid phosphatase (TRAP) activity of osteoclasts. The osteoprotective effects of MTE were comparable to those of estrogenic isoflavone. Low-dose combination of MTE and isoflavone had a pharmacological synergy that may be useful for osteogenic activity. This study attempted to reveal the suppressive effects of MTE on bone loss. C57BL/6 female mice were ovariectomized (OVX) as a model for postmenopausal osteopenia and orally administered 10 mg/kg MTE or silibinin for 8 weeks. The sham-operated mice served as estrogen controls. The treatment of ovariectomized mice with nontoxic MTE and silibinin improved femoral bone mineral density and serum receptor activator of nuclear factor-κB ligand/osteoprotegerin ratio, an index of osteoclastogenic stimulus. In addition, the administration of MTE or silibinin inhibited femoral bone loss induced by ovariectomy and suppressed femoral TRAP activity and cathepsin K induction responsible for osteoclastogenesis and bone resorption. Collectively, oral dosage of MTE containing silibinin in the preclinical setting is effective in preventing estrogen deficiency-induced bone loss. PMID:23781510

Kit W-sh Mutation Prevents Cancellous Bone Loss during Calcium Deprivation.

PubMed

Lotinun, Sutada; Suwanwela, Jaijam; Poolthong, Suchit; Baron, Roland

2018-01-01

Calcium is essential for normal bone growth and development. Inadequate calcium intake increases the risk of osteoporosis and fractures. Kit ligand/c-Kit signaling plays an important role in regulating bone homeostasis. Mice with c-Kit mutations are osteopenic. The present study aimed to investigate whether impairment of or reduction in c-Kit signaling affects bone turnover during calcium deprivation. Three-week-old male WBB6F1/J-Kit W /Kit W-v /J (W/W v ) mice with c-Kit point mutation, Kit W-sh /HNihrJaeBsmJ (W sh /W sh ) mice with an inversion mutation in the regulatory elements upstream of the c-Kit promoter region, and their wild-type controls (WT) were fed either a normal (0.6% calcium) or a low calcium diet (0.02% calcium) for 3 weeks. μCT analysis indicated that both mutants fed normal calcium diet had significantly decreased cortical thickness and cancellous bone volume compared to WT. The low calcium diet resulted in a comparable reduction in cortical bone volume and cortical thickness in the W/W v and W sh /W sh mice, and their corresponding controls. As expected, the low calcium diet induced cancellous bone loss in the W/W v mice. In contrast, W sh /W sh cancellous bone did not respond to this diet. This c-Kit mutation prevented cancellous bone loss by antagonizing the low calcium diet-induced increase in osteoblast and osteoclast numbers in the W sh /W sh mice. Gene expression profiling showed that calcium deficiency increased Osx, Ocn, Alp, type I collagen, c-Fms, M-CSF, and RANKL/OPG mRNA expression in controls; however, the W sh mutation suppressed these effects. Our findings indicate that although calcium restriction increased bone turnover, leading to osteopenia, the decreased c-Kit expression levels in the W sh /W sh mice prevented the low calcium diet-induced increase in cancellous bone turnover and bone loss but not the cortical bone loss.

Vitamin K catabolite inhibition of ovariectomy-induced bone loss: structure-activity relationship considerations.

PubMed

Soper, Robin J; Oguz, Cenk; Emery, Roger; Pitsillides, Andrew A; Hodges, Stephen J

2014-08-01

The potential benefit of vitamin K as a therapeutic in osteoporosis is controversial and the vitamin K regimen being used clinically (45 mg/day) employs doses that are many times higher than required to ensure maximal gamma-carboxylation of the vitamin K-dependent bone proteins. We therefore tested the hypothesis that vitamin K catabolites, 5-carbon (CAN5C) and 7-carbon carboxylic acid (CAN7C) aliphatic side-chain derivatives of the naphthoquinone moiety exert an osteotrophic role consistent with the treatment of osteoporosis. Osteoblast-like MG63 cell cultures were challenged with lipopolysaccharide and the levels of interleukin-6, an osteoclastogenic cytokine, measured with and without catabolites; low concentrations of CAN7C significantly inhibited interleukin-6 release, but CAN5C did not. In models of bone loss induced by ovariectomy or sciatic neurectomy in C57BL/6 mice, we found that the rarer CAN7C catabolite markedly restricted ovariectomy-induced bone loss and possibly limited sciatic neurectomy-induced bone loss. CAN7C activity depends on a free carboxylic acid and its particular side-chain structure. These in vivo data indicate for the first time that the clinical utility of vitamin K for osteoporosis may reside in an unusual catabolite. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synergistic effects of green tea polyphenols and alphacalcidol on chronic inflammation-induced bone loss in female rats

USDA-ARS?s Scientific Manuscript database

Summary: Studies suggest that green tea polyphenols (GTP) or alphacalcidol is promising agent for preventing bone loss. Findings that GTP supplementation in the drinking water plus alphacalcidol administration resulted in increased bone mass via a decrease of oxidative stress and inflammation sugges...

Circulating microRNAs Correlated with Bone Loss Induced by 45 Days of Bed Rest

PubMed Central

Ling, Shukuan; Zhong, Guohui; Sun, Weijia; Liang, Fengji; Wu, Feng; Li, Hongxing; Li, Yuheng; Zhao, Dingsheng; Song, Jinping; Jin, Xiaoyan; Wu, Xiaorui; Song, Hailin; Li, Qi; Li, Yinghui; Chen, Shanguang; Xiong, Jianghui; Li, Yingxian

2017-01-01

The purpose of this study was to find the circulating microRNAs (miRNAs) co-related with bone loss induced by bed rest, and testify whether the selected miRNAs could reflect the bone mineral status of human after bed-rest. We analyzed plasma miRNA levels of 16 subjects after 45 days of −6° head-down tilt bed rest, which is a reliable model for the simulation of microgravity. We characterize the circulating miRNA profile in individuals after bed rest and identify circulating miRNAs which can best reflect the level of bone loss induced by bed rest. Expression profiling of circulating miRNA revealed significant downregulation of 37 miRNAs and upregulation of 2 miRNAs, while only 11 of the downregulated miRNAs were further validated in a larger volunteer cohort using qPCR. We found that 10 of these 11 miRNAs (miR-103, 130a, 1234, 1290, 151-5p, 151-3p, 199a-3p, 20a, 363, and 451a) had ROC curve that distinguished the status after bed rest. Importantly, significant positive correlations were identified between bone loss parameters and several miRNAs, eventually miR-1234 showed clinical significance in detecting the bone loss of individuals after 45 days of bed rest. PMID:28261104

Prevention of glucocorticoid induced bone changes with beta-ecdysone

PubMed Central

Dai, Weiwei; Jiang, Li; Lay, Yu-An Evan; Chen, Haiyan; Jin, Guoqin; Zhang, Hongliang; Kot, Alex; Ritchie, Robert O.; Lane, Nancy E.; Yao, Wei

2015-01-01

Beta-ecdysone (βEcd) is a phytoecdysteroid found in the dry roots and seeds of the asteraceae and achyranthes plants, and is reported to increase osteogenesis in vitro. Since glucocorticoid (GCs) excess is associated with a decrease in bone formation, the purpose of this study was to determine if treatment with βEcd could prevent GC-induced osteoporosis. Two-month-old male Swiss-Webster mice (n=8-10/group) were randomized to either placebo or slow release prednisolone pellets (3.3mg/kg/d) and treated with vehicle control or βEcd (0.5mg/kg/d) for 21 days. GC treatment inhibited age-dependent trabecular gain and cortical bone expansion and this was accompanied by a 30-50% lower bone formation rate (BFR) at both the endosteal and periosteal surfaces. Mice treated with only βEcd significantly increased bone formation on endosteal and periosteal bone surfaces, and increased cortical bone mass were their controls to compare to GC alone. Concurrent treatment of βEcd and GC completely prevented the GC-induced reduction in BFR, trabecular bone volume and partially prevented cortical bone loss. In vitro studies determined that βEcd prevented the GC increase in autophagy of the bone marrow stromal cells as well as in whole bone. In summary, βEcd prevented GC induced changes in bone formation, bone cell viability and bone mass. Additional studies are warranted of βEcd for the treatment of GC induced bone loss. PMID:25585248

Prevention of glucocorticoid induced bone changes with beta-ecdysone.

PubMed

Dai, Weiwei; Jiang, Li; Lay, Yu-An Evan; Chen, Haiyan; Jin, Guoqin; Zhang, Hongliang; Kot, Alexander; Ritchie, Robert O; Lane, Nancy E; Yao, Wei

2015-05-01

Beta-ecdysone (βEcd) is a phytoecdysteroid found in the dry roots and seeds of the asteraceae and achyranthes plants, and is reported to increase osteogenesis in vitro. Since glucocorticoid (GC) excess is associated with a decrease in bone formation, the purpose of this study was to determine if treatment with βEcd could prevent GC-induced osteoporosis. Two-month-old male Swiss-Webster mice (n=8-10/group) were randomized to either placebo or slow release prednisolone pellets (3.3mg/kg/day) and treated with vehicle control or βEcd (0.5mg/kg/day) for 21days. GC treatment inhibited age-dependent trabecular gain and cortical bone expansion and this was accompanied by a 30-50% lower bone formation rate (BFR) at both the endosteal and periosteal surfaces. Mice treated with only βEcd significantly increased bone formation on the endosteal and periosteal bone surfaces, and increased cortical bone mass were their controls to compare to GC alone. Concurrent treatment of βEcd and GC completely prevented the GC-induced reduction in BFR, trabecular bone volume and partially prevented cortical bone loss. In vitro studies determined that βEcd prevented the GC increase in autophagy of the bone marrow stromal cells as well as in whole bone. In summary, βEcd prevented GC induced changes in bone formation, bone cell viability and bone mass. Additional studies are warranted of βEcd for the treatment of GC induced bone loss. Copyright © 2015 Elsevier Inc. All rights reserved.

Biophotonics and Bone Biology

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory; Fischer, David; Asipauskas, Marius; Chauhan, Chirag; Compitello, Nicole; Burke, Jamie; Tate, Melissa Knothe

2004-01-01

One of the more-serious side effects of extended space flight is an accelerated bone loss [Bioastronautics Critical Path Roadmap, http://research.hq.nasa.gov/code_u/bcpr/index.cfm]. Rates of bone loss are highest in the weight-bearing bones of the hip and spine regions, and the average rate of bone loss as measured by bone mineral density measurements is around 1.2% per month for persons in a microgravity environment. It shows that an extrapolation of the microgravity induced bone loss rates to longer time scales, such as a 2.5 year round-trip to Mars (6 months out at 0 g, 1.5 year stay on Mars at 0.38 g, 6 months back at 0 g), could severely compromise the skeletal system of such a person.

Regulatory mechanism of food factors in bone metabolism and prevention of osteoporosis.

PubMed

Yamaguchi, Masayoshi

2006-11-01

Aging induces a decrease in bone mass, and osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public health problem. Bone loss with increasing age may be due to decreased bone formation and increased bone resorption. Pharmacologic and nutritional factors may prevent bone loss with aging, although chemical compounds in food and plants which act on bone metabolism are poorly understood. We have found that isoflavones (including genistein and daidzein), which are contained in soybeans, have a stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption, thereby increasing bone mass. Menaquinone-7, an analogue of vitamin K(2) which is abundant in fermented soybeans, has been demonstrated to stimulate osteoblastic bone formation and to inhibit osteoclastic bone resorption. Of various carotenoids, beta-cryptoxanthin, which is abundant in Satsuma mandarin (Citrus unchiu MARC), has a stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption. The supplementation of these factors has a preventive effect on bone loss induced by ovariectomy in rats, which are an animal model of osteoporosis, and their intake has been shown to have a stimulatory effect on bone mass in humans. Factors with an anabolic effect on bone metabolism were found in extracts obtained from wasabi leafstalk (Wasabi japonica MATSUM), the marine alga Sargassum horneri, and bee pollen Cistus ladaniferus. Phytocomponent p-hydroxycinnamic acid was also found to have an anabolic effect on bone metabolism. Food chemical factors thus play a role in bone health and may be important in the prevention of bone loss with increasing age.

The Lyme Disease Pathogen Borrelia burgdorferi Infects Murine Bone and Induces Trabecular Bone Loss.

PubMed

Tang, Tian Tian; Zhang, Lucia; Bansal, Anil; Grynpas, Marc; Moriarty, Tara J

2017-02-01

Lyme disease is caused by members of the Borrelia burgdorferi sensu lato species complex. Arthritis is a well-known late-stage pathology of Lyme disease, but the effects of B. burgdorferi infection on bone at sites other than articular surfaces are largely unknown. In this study, we investigated whether B. burgdorferi infection affects bone health in mice. In mice inoculated with B. burgdorferi or vehicle (mock infection), we measured the presence of B. burgdorferi DNA in bones, bone mineral density (BMD), bone formation rates, biomechanical properties, cellular composition, and two- and three-dimensional features of bone microarchitecture. B. burgdorferi DNA was detected in bone. In the long bones, increasing B. burgdorferi DNA copy number correlated with reductions in areal and trabecular volumetric BMDs. Trabecular regions of femora exhibited significant, copy number-correlated microarchitectural disruption, but BMD, microarchitectural, and biomechanical properties of cortical bone were not affected. Bone loss in tibiae was not due to increased osteoclast numbers or bone-resorbing surface area, but it was associated with reduced osteoblast numbers, implying that bone loss in long bones was due to impaired bone building. Osteoid-producing and mineralization activities of existing osteoblasts were unaffected by infection. Therefore, deterioration of trabecular bone was not dependent on inhibition of osteoblast function but was more likely caused by blockade of osteoblastogenesis, reduced osteoblast survival, and/or induction of osteoblast death. Together, these data represent the first evidence that B. burgdorferi infection induces bone loss in mice and suggest that this phenotype results from inhibition of bone building rather than increased bone resorption. Copyright © 2017 Tang et al.

Awareness, concern, and communication between physicians and patients on bone health in cancer.

PubMed

Tripathy, Debu; Durie, Brian G M; Mautner, Beatrice; Ferenz, Krag S; Moul, Judd W

2014-06-01

This study aims to explore physician-patient communications about bone metastases and cancer treatment-induced bone loss (CTIBL). The study utilizes online survey of patients with breast cancer, prostate cancer, and multiple myeloma, and the physicians who treat them. Even though 69 and 48 % of patients with nonmetastatic breast and prostate cancer aware of treatment-induced bone loss, only 39 and 23 %, respectively, were concerned about bone loss. Yet, 62 and 71 % of oncologists treating breast and prostate cancer felt that their patients were concerned. Among patients with metastatic breast and prostate cancer, two thirds had not discussed treatment for bone metastases with their doctor; when discussed, 88 and 91 % of discussions were initiated by the doctor, usually prior to initiating treatment. Most myeloma patients (77 %) had discussed treatment options with their physicians; 99 % of hematologists reported discussing treatment of bone disease with patients. Physicians are primary sources of information to patients regarding bone health. There is a gap between what physicians assume their patients know about bone health and the patients' perceptions, presenting a need for systematic awareness and education.

In vivo bone remodeling rates determination and compressive stiffness variations before, during 60 days bed rest and two years follow up: A micro-FE-analysis from HR-pQCT measurements of the berlin Bed Rest Study-2

NASA Astrophysics Data System (ADS)

Ritter, Zully; Belavy, Daniel; Baumann, Wolfgang W.; Felsenberg, Dieter

2017-03-01

Bed rest studies are used for simulation and study of physiological changes as observed in unloading/non-gravity environments. Amongst others, bone mass reduction, similar as occurring due to aging osteoporosis, combined with bio-fluids redistribution and muscle atrophy have been observed and analyzed. Advanced radiological methods of high resolution such as HR-pQCT (XtremeCT) allow 3D-visualizing in vivo bone remodeling processes occurring during absence/reduction of mechanical stimuli (0 to <1 g) as simulated by bed rest. Induced bone micro-structure (e.g. trabecular number, cortical thickness, porosity) and density variations can be quantified. However, these parameters are average values of each sample and important information regarding bone mass distribution and within bone mechanical behaviour is lost. Finite element models with hexa-elements of identical size as the HR-pQCT measurements (0.082 mm×0.082 mm×0.082 mm, ca. 7E6 elements/sample) can be used for subject-specific in vivo stiffness calculation. This technique also allows quantifying if bone microstructural changes represent a risk of mechanical bone collapse (fracture).

Oxidation-specific epitopes restrain bone formation.

PubMed

Ambrogini, Elena; Que, Xuchu; Wang, Shuling; Yamaguchi, Fumihiro; Weinstein, Robert S; Tsimikas, Sotirios; Manolagas, Stavros C; Witztum, Joseph L; Jilka, Robert L

2018-06-06

Atherosclerosis and osteoporosis are epidemiologically linked and oxidation specific epitopes (OSEs), such as phosphocholine (PC) of oxidized phospholipids (PC-OxPL) and malondialdehyde (MDA), are pathogenic in both. The proatherogenic effects of OSEs are opposed by innate immune antibodies. Here we show that high-fat diet (HFD)-induced bone loss is attenuated in mice expressing a single chain variable region fragment of the IgM E06 (E06-scFv) that neutralizes PC-OxPL, by increasing osteoblast number and stimulating bone formation. Similarly, HFD-induced bone loss is attenuated in mice expressing IK17-scFv, which neutralizes MDA. Notably, E06-scFv also increases bone mass in mice fed a normal diet. Moreover, the levels of anti-PC IgM decrease in aged mice. We conclude that OSEs, whether produced chronically or increased by HFD, restrain bone formation, and that diminished defense against OSEs may contribute to age-related bone loss. Anti-OSEs, therefore, may represent a novel therapeutic approach against osteoporosis and atherosclerosis simultaneously.

Pioglitazone-induced bone loss in diabetic rats and its amelioration by berberine: A portrait of molecular crosstalk.

PubMed

Adil, Mohammad; Mansoori, Mohd Nizam; Singh, Divya; Kandhare, Amit Dattatraya; Sharma, Manju

2017-10-01

Diabetes mellitus and osteoporosis both are high prevalence disorders, especially in the elderly population. Pioglitazone, a PPAR-γ agonist associated with bone loss and risk of fracture in type 2 diabetes mellitus patients. In this study, ameliorative effect of berberine against pioglitazone-induced bone loss in diabetic rats and possible mechanisms has been explored. Diabetes was induced in male Wistar albino rats by streptozotocin (65 mg/kg, i.v.) after 15min of nicotinamide (230mg/kg, i.p.) administration. Diabetic rats were treated orally with pioglitazone (10mg/kg) and berberine (100mg/kg) alone and in combination of both for 12 weeks. Femur of each rat was isolated and evaluated for the bone micro-architecture, BMD, histology and mRNA expression of PPAR-γ, AMPK, and bone turnover markers (RANKL, OPG, Runx2, and osteocalcin). Urinary calcium and serum TRAP was also measured. Treatment of pioglitazone and berberine alone and in combination significantly ameliorate abnormal blood glucose, serum insulin, and HbA1c levels in streptozotocin-induced diabetic rats. Pioglitazone treatment significantly increased urinary calcium, serum TRAP, mRNA expression of RANKL, PPAR-γ as well as significantly decreased Runx2, OPG, osteocalcin and AMPK levels in diabetic rats. Pioglitazone administration also shows detrimental effect on femur epiphysis micro-architecture, BMD and histology. Whereas, berberine treatment alone and in combination with pioglitazone remarkably ameliorates the abnormal urinary calcium, mRNA expression of AMPK, bone turnover markers, femur epiphysis micro-architecture, histology and also increases BMD in diabetic rats. In conclusion, berberine shows protective effect against pioglitazone-induced bone loss in diabetic rats possibly through AMPK activation pathway. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Impact of intra- and extra-osseous soft tissue composition on changes in bone mineral density with weight loss and regain.

PubMed

Bosy-Westphal, Anja; Later, Wiebke; Schautz, Britta; Lagerpusch, Merit; Goele, Kristin; Heller, Martin; Glüer, Claus-C; Müller, Manfred J

2011-07-01

Recent studies report a significant gain in bone mineral density (BMD) after diet-induced weight loss. This might be explained by a measurement artefact. We therefore investigated the impact of intra- and extra-osseous soft tissue composition on bone measurements by dual X-ray absorptiometry (DXA) in a longitudinal study of diet-induced weight loss and regain in 55 women and 17 men (19-46 years, BMI 28.2-46.8 kg/m(2)). Total and regional BMD were measured before and after 12.7 ± 2.2 week diet-induced weight loss and 6 months after significant weight regain (≥30%). Hydration of fat free mass (FFM) was assessed by a 3-compartment model. Skeletal muscle (SM) mass, extra-osseous adipose tissue, and bone marrow were measured by whole body magnetic resonance imaging (MRI). Mean weight loss was -9.2 ± 4.4 kg (P < 0.001) and was followed by weight regain in a subgroup of 24 subjects (+6.3 ± 2.9 kg; P < 0.001). With weight loss, bone marrow and extra-osseous adipose tissue decreased whereas BMD increased at the total body, lumbar spine, and the legs (women only) but decreased at the pelvis (men only, all P < 0.05). The decrease in BMD(pelvis) correlated with the loss in visceral adipose tissue (VAT) (P < 0.05). Increases in BMD(legs) were reversed after weight regain and inversely correlated with BMD(legs) decreases. No other associations between changes in BMD and intra- or extra-osseous soft tissue composition were found. In conclusion, changes in extra-osseous soft tissue composition had a minor contribution to changes in BMD with weight loss and decreases in bone marrow adipose tissue (BMAT) were not related to changes in BMD.

Towards human exploration of space: the THESEUS review series on muscle and bone research priorities.

PubMed

Lang, Thomas; Van Loon, Jack J W A; Bloomfield, Susan; Vico, Laurence; Chopard, Angele; Rittweger, Joern; Kyparos, Antonios; Blottner, Dieter; Vuori, Ilkka; Gerzer, Rupert; Cavanagh, Peter R

2017-01-01

Without effective countermeasures, the musculoskeletal system is altered by the microgravity environment of long-duration spaceflight, resulting in atrophy of bone and muscle tissue, as well as in deficits in the function of cartilage, tendons, and vertebral disks. While inflight countermeasures implemented on the International Space Station have evidenced reduction of bone and muscle loss on low-Earth orbit missions of several months in length, important knowledge gaps must be addressed in order to develop effective strategies for managing human musculoskeletal health on exploration class missions well beyond Earth orbit. Analog environments, such as bed rest and/or isolation environments, may be employed in conjunction with large sample sizes to understand sex differences in countermeasure effectiveness, as well as interaction of exercise with pharmacologic, nutritional, immune system, sleep and psychological countermeasures. Studies of musculoskeletal biomechanics, involving both human subject and computer simulation studies, are essential to developing strategies to avoid bone fractures or other injuries to connective tissue during exercise and extravehicular activities. Animal models may be employed to understand effects of the space environment that cannot be modeled using human analog studies. These include studies of radiation effects on bone and muscle, unraveling the effects of genetics on bone and muscle loss, and characterizing the process of fracture healing in the mechanically unloaded and immuno-compromised spaceflight environment. In addition to setting the stage for evidence-based management of musculoskeletal health in long-duration space missions, the body of knowledge acquired in the process of addressing this array of scientific problems will lend insight into the understanding of terrestrial health conditions such as age-related osteoporosis and sarcopenia.

Protein and Essential Amino Acids to Protect Musculoskeletal Health during Spaceflight: Evidence of a Paradox?

PubMed Central

Hackney, Kyle J.; English, Kirk L.

2014-01-01

Long-duration spaceflight results in muscle atrophy and a loss of bone mineral density. In skeletal muscle tissue, acute exercise and protein (e.g., essential amino acids) stimulate anabolic pathways (e.g., muscle protein synthesis) both independently and synergistically to maintain neutral or positive net muscle protein balance. Protein intake in space is recommended to be 12%–15% of total energy intake (≤1.4 g∙kg−1∙day−1) and spaceflight is associated with reduced energy intake (~20%), which enhances muscle catabolism. Increasing protein intake to 1.5–2.0 g∙kg−1∙day−1 may be beneficial for skeletal muscle tissue and could be accomplished with essential amino acid supplementation. However, increased consumption of sulfur-containing amino acids is associated with increased bone resorption, which creates a dilemma for musculoskeletal countermeasures, whereby optimizing skeletal muscle parameters via essential amino acid supplementation may worsen bone outcomes. To protect both muscle and bone health, future unloading studies should evaluate increased protein intake via non-sulfur containing essential amino acids or leucine in combination with exercise countermeasures and the concomitant influence of reduced energy intake. PMID:25370374

Radiation activated CHK1/MEPE pathway may contribute to microgravity-induced bone density loss

NASA Astrophysics Data System (ADS)

Zhang, Xiangming; Wang, Ping; Wang, Ya

2015-11-01

Bone density loss in astronauts on long-term space missions is a chief medical concern. Microgravity in space is the major cause of bone density loss (osteopenia), and it is believed that high linear energy transfer (LET) radiation in space exacerbates microgravity-induced bone density loss; however, the mechanism remains unclear. It is known that acidic serine- and aspartate-rich motif (ASARM) as a small peptide released by matrix extracellular phosphoglycoprotein (MEPE) promotes osteopenia. We previously discovered that MEPE interacted with checkpoint kinase 1 (CHK1) to protect CHK1 from ionizing radiation promoted degradation. In this study, we addressed whether the CHK1-MEPE pathway activated by radiation contributes to the effects of microgravity on bone density loss. We examined the CHK1, MEPE and secreted MEPE/ASARM levels in irradiated (1 Gy of X-ray) and rotated cultured human osteoblast cells. The results showed that radiation activated CHK1, decreased the levels of CHK1 and MEPE in human osteoblast cells and increased the release of MEPE/ASARM. These results suggest that the radiation-activated CHK1/MEPE pathway exacerbates the effects of microgravity on bone density loss, which may provide a novel targeting factor/pathway for a future countermeasure design that could contribute to reducing osteopenia in astronauts.

Soy Isoflavones and Osteoporotic Bone Loss: A Review with an Emphasis on Modulation of Bone Remodeling

PubMed Central

Zheng, Xi; Lee, Sun-Kyeong

2016-01-01

Abstract Osteoporosis is an age-related disorder that affects both women and men, although estrogen deficiency induced by menopause accelerates bone loss in older women. As the demographic shifts to a more aged population, a growing number of men and women will be afflicted with osteoporosis. Since the current drug therapies available have multiple side effects, including increased risk of developing certain types of cancer or complications, a search for potential nonpharmacologic alternative therapies for osteoporosis is of prime interest. Soy isoflavones (SI) have demonstrated potential bone-specific effects in a number of studies. This article provides a systematic review of studies on osteoporotic bone loss in relation to SI intake from diet or supplements to comprehensively explain how SI affect the modulation of bone remodeling. Evidence from epidemiologic studies supports that dietary SI attenuate menopause-induced osteoporotic bone loss by decreasing bone resorption and stimulating bone formation. Other studies have also illustrated that bone site-specific trophic and synergistic effects combined with exercise intervention might contribute to improve the bioavailability of SI or strengthen the bone-specific effects. To date, however, the effects of dietary SI on osteoporotic bone loss remain inconclusive, and study results vary from study to study. The current review will discuss the potential factors that result in the conflicting outcomes of these studies, including dosages, intervention materials, study duration, race, and genetic differences. Further well-designed studies are needed to fully understand the underlying mechanism and evaluate the effects of SI on osteoporosis in humans. PMID:26670451

Rapid Loss of Bone Mass and Strength in Mice after Abdominal Irradiation

PubMed Central

Jia, Dan; Gaddy, Dana; Suva, Larry J.; Corry, Peter M.

2011-01-01

Localized irradiation is a common treatment modality for malignancies in the pelvic-abdominal cavity. We report here on the changes in bone mass and strength in mice 7–14 days after abdominal irradiation. Male C57BL/6 mice of 10–12 weeks of age were given a single-dose (0, 5, 10, 15 or 20 Gy) or fractionated (3 Gy × 2 per day × 7.5 days) X rays to the abdomen and monitored daily for up to 14 days. A decrease in the serum bone formation marker and ex vivo osteoblast differentiation was detected 7 days after a single dose of radiation, with little change in the serum bone resorption marker and ex vivo osteoclast formation. A single dose of radiation elicited a loss of bone mineral density (BMD) within 14 days of irradiation. The BMD loss was up to 4.1% in the whole skeleton, 7.3% in tibia, and 7.7% in the femur. Fractionated abdominal irradiation induced similar extents of BMD loss 10 days after the last fraction: 6.2% in the whole skeleton, 5.1% in tibia, and 13.8% in the femur. The loss of BMD was dependent on radiation dose and was more profound in the trabecula-rich regions of the long bones. Moreover, BMD loss in the total skeleton and the femurs progressed with time. Peak load and stiffness in the mid-shaft tibia from irradiated mice were 11.2–14.2% and 11.5–25.0% lower, respectively, than sham controls tested 7 days after a single-dose abdominal irradiation. Our data demonstrate that abdominal irradiation induces a rapid loss of BMD in the mouse skeleton. These effects are bone type- and region-specific but are independent of radiation fractionation. The radiation-induced abscopal damage to the skeleton is manifested by the deterioration of biomechanical properties of the affected bone. PMID:21859327

Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation).

PubMed

McGee-Lawrence, Meghan E; Wojda, Samantha J; Barlow, Lindsay N; Drummer, Thomas D; Castillo, Alesha B; Kennedy, Oran; Condon, Keith W; Auger, Janene; Black, Hal L; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

2009-12-01

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse-induced bone loss in bears into novel treatments for osteoporosis.

Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation)

PubMed Central

McGee-Lawrence, Meghan E.; Wojda, Samantha J.; Barlow, Lindsay N.; Drummer, Thomas D.; Castillo, Alesha B.; Kennedy, Oran; Condon, Keith W.; Auger, Janene; Black, Hal L.; Nelson, O. Lynne; Robbins, Charles T.; Donahue, Seth W.

2009-01-01

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse induced bone loss in bears into novel treatments for osteoporosis. PMID:19703606

Bone Proteoglycan Changes During Skeletal Unloading

NASA Technical Reports Server (NTRS)

Yamauchi, M.; Uzawa, K.; Pornprasertsuk, S.; Arnaud, S.; Grindeland, R.; Grzesik, W.

1999-01-01

Skeletal adaptability to mechanical loads is well known since the last century. Disuse osteopenia due to the microgravity environment is one of the major concerns for space travelers. Several studies have indicated that a retardation of the mineralization process and a delay in matrix maturation occur during the space flight. Mineralizing fibrillar type I collagen possesses distinct cross-linking chemistries and their dynamic changes during mineralization correlate well with its function as a mineral organizer. Our previous studies suggested that a certain group of matrix proteoglycans in bone play an inhibitory role in the mineralization process through their interaction with collagen. Based on these studies, we hypothesized that the altered mineralization during spaceflight is due in part to changes in matrix components secreted by cells in response to microgravity. In this study, we employed hindlimb elevation (tail suspension) rat model to study the effects of skeletal unloading on matrix proteoglycans in bone.

Influence of controlled immediate loading and implant design on peri-implant bone formation.

PubMed

Vandamme, Katleen; Naert, Ignace; Geris, Liesbet; Vander Sloten, Jozef; Puers, Robert; Duyck, Joke

2007-02-01

Tissue formation at the implant interface is known to be sensitive to mechanical stimuli. The aim of the study was to compare the bone formation around immediately loaded versus unloaded implants in two different implant macro-designs. A repeated sampling bone chamber with a central implant was installed in the tibia of 10 rabbits. Highly controlled loading experiments were designed for a cylindrical (CL) and screw-shaped (SL) implant, while the unloaded screw-shaped (SU) implant served as a control. An F-statistic model with alpha=5% determined statistical significance. A significantly higher bone area fraction was observed for SL compared with SU (p<0.0001). The mineralized bone fraction was the highest for SL and significantly different from SU (p<0.0001). The chance that osteoid- and bone-to-implant contact occurred was the highest for SL and significantly different from SU (p<0.0001), but not from CL. When bone-to-implant contact was observed, a loading (SL versus SU: p=0.0049) as well as an implant geometry effect (SL versus CL: p=0.01) was found, in favour of the SL condition. Well-controlled immediate implant loading accelerates tissue mineralization at the interface. Adequate bone stimulation via mechanical coupling may account for the larger bone response around the screw-type implant compared with the cylindrical implant.

Genistein suppresses Prevotella intermedia lipopolysaccharide-induced inflammatory response in macrophages and attenuates alveolar bone loss in ligature-induced periodontitis.

PubMed

Choi, Eun-Young; Bae, Seung Han; Ha, Min Hee; Choe, So-Hui; Hyeon, Jin-Yi; Choi, Jeom-Il; Choi, In Soon; Kim, Sung-Jo

2016-02-01

Genistein is a major isoflavone subclass of flavonoids found in soybean and a potent tyrosine kinase inhibitor. The present study aimed to assess the effect of genistein on the production of proinflammatory mediators in murine macrophages stimulated with lipopolysaccharide (LPS) isolated from Prevotella intermedia, a pathogen associated with different forms of periodontal disease, and to evaluate its possible influence on alveolar bone loss in ligature-induced periodontitis using micro-computed tomography (micro-CT) analysis as well. LPS was isolated from P. intermedia ATCC 25611 by using the standard hot phenol-water method. Culture supernatants were analyzed for nitric oxide (NO) and interleukin-6 (IL-6). Inducible NO synthase (iNOS) protein expression was evaluated by immunoblot analysis. Real-time PCR was carried out to measure iNOS and IL-6 mRNA expression. In addition, effect of genistein on alveolar bone loss was evaluated in a rat model of experimental periodontitis using micro-CT analysis. Genistein significantly attenuated P. intermedia LPS-induced production of iNOS-derived NO and IL-6 with attendant decrease in their mRNA expression in RAW264.7 cells. In addition, when genistein was administered to rats, decreases in alveolar bone height and bone volume fraction induced by ligature placement were significantly inhibited. Genistein administration also prevented ligature-induced alterations in the microstructural parameters of trabecular bone, including trabecular thickness, trabecular separation, bone mineral density and structure model index. While additional studies are required, we suggest that genistein could be utilized for the therapy of human periodontitis in the future. Copyright © 2015 Elsevier Ltd. All rights reserved.

Screening, prevention, detection, and treatment of cancer therapy-induced bone loss in patients with breast cancer.

PubMed

Limburg, Connie E

2007-01-01

To identify protocols to screen, detect, prevent, and treat cancer therapy-induced bone loss resulting in osteoporosis in patients with breast cancer. Published books and articles. Normal bone remodeling is affected by hormonal stimulation. Breast cancer therapies target hormones that promote cancer cell growth. Chemotherapy regimens and hormone ablation may cause ovarian failure, resulting in decreased hormone levels. A decrease in hormones, in estrogen- and progesterone-positive and -negative patients, introduces an environment for decreased bone remodeling, which may result in thinning bone and osteoporosis. The acceleration of bone loss leading to osteoporosis can result in higher fracture rates among breast cancer survivors. With proper use of screening tools, patient education, and advice about lifestyle changes, all prior to cancer treatment, healthcare professionals may decrease or prevent bone loss in patients with breast cancer. Doing so minimizes healthcare costs and decreases morbidity and mortality rates in breast cancer survivors. As more individuals diagnosed with breast cancer are surviving for extended periods of time, oncology nurses are providing long-term follow-up care. Part of the care should include proper screening and patient education for healthier recovery and prevention of further healthcare complications as a result of cancer treatment.

OSTEOCLAST-INDUCED FOXP3+ CD8 T-CELLS LIMIT BONE LOSS IN MICE

PubMed Central

Buchwald, Zachary S.; Kiesel, Jennifer R.; Yang, Chang; DiPaolo, Richard; Novack, Deborah V.; Aurora, Rajeev

2014-01-01

Osteoimmunology is the crosstalk between the skeletal and immune system. We have previously shown in vitro that osteoclasts (OC) crosspresent antigens to induce FoxP3 in CD8 T-cells (OCiTcREG), which then suppress osteoclast activity. Here we assessed the ability of OC-iTcREG to limit bone resorption in vivo. Mice lacking CD8 T-cells lose more bone in response to RANKL (Tnfsf11) administration. Using adoptive transfer experiments we demonstrate that FoxP3+ CD8 T-cells limit bone loss by RANKL administration. In ovariectomized mice, a murine model of postmenopausal osteoporosis, OC-iTcREG limited bone loss and increased bone density as assessed by serum markers, micro computed tomography (μCT) and histomorphometry. Indeed, OC-iTcREG—treated ovariectomized mice had decreased levels of effector T-cells in the bone marrow compared to untreated mice, and increased bone formation rates relative to bisphosphonate-treated mice. Our results provide the first in vivo evidence that OC-iTcREG have anti-resorptive activity and repress the immune system, thus extending the purview of osteoimmunology. PMID:23756229

Protection of trabecular bone in ovariectomized rats by turmeric (Curcuma longa L.) is dependent on extract composition.

PubMed

Wright, Laura E; Frye, Jennifer B; Timmermann, Barbara N; Funk, Janet L

2010-09-08

Extracts prepared from turmeric (Curcuma longa L., [Zingiberaceae]) containing bioactive phenolic curcuminoids were evaluated for bone-protective effects in a hypogonadal rat model of postmenopausal osteoporosis. Three-month female Sprague-Dawley rats were ovariectomized (OVX) and treated with a chemically complex turmeric fraction (41% curcuminoids by weight) or a curcuminoid-enriched turmeric fraction (94% curcuminoids by weight), both dosed at 60 mg/kg 3x per week, or vehicle alone. Effects of two months of treatment on OVX-induced bone loss were followed prospectively by serial assessment of bone mineral density (BMD) of the distal femur using dual-energy X-ray absorptiometry (DXA), while treatment effects on trabecular bone microarchitecture were assessed at two months by microcomputerized tomography (microCT). Chemically complex turmeric did not prevent bone loss, however, the curcuminoid-enriched turmeric prevented up to 50% of OVX-induced loss of trabecular bone and also preserved the number and connectedness of the strut-like trabeculae. These results suggest that turmeric may have bone-protective effects but that extract composition is a critical factor.

Protection of Trabecular Bone in Ovariectomized Rats by Turmeric (Curcuma longa L.) is Dependent on Extract Composition

PubMed Central

Wright, Laura E.; Frye, Jennifer B.; Timmermann, Barbara N.; Funk, Janet L.

2010-01-01

Extracts prepared from turmeric (Curcuma longa L., [Zingiberaceae]) containing bioactive phenolic curcuminoids were evaluated for bone-protective effects in a hypogonadal rat model of postmenopausal osteoporosis. Three-month female Sprague Dawley rats were ovariectomized (OVX) and treated with a chemically complex turmeric fraction (41% curcuminoids by weight) or a curcuminoid-enriched turmeric fraction (94% curcuminoids by weight), both dosed at 60mg/kg 3x per week, or vehicle alone. Effects of two months of treatment on OVX-induced bone loss were followed prospectively by serial assessment of bone mineral density (BMD) of the distal femur using dual-energy x-ray absorptiometry (DXA), while treatment effects on trabecular bone microarchitecture were assessed at two months by micro-computerized tomography (μCT). Chemically complex turmeric did not prevent bone loss, however, the curcuminoid-enriched turmeric prevented up to 50% of OVX-induced loss of trabecular bone and also preserved the number and connectedness of the strut-like trabeculae. These results suggest that turmeric may have bone-protective effects but that extract composition is a critical factor. PMID:20695490

Mutant CCL2 Protein Coating Mitigates Wear Particle-Induced Bone Loss in a Murine Continuous Polyethylene Infusion Model

PubMed Central

Nabeshima, Akira; Pajarinen, Jukka; Lin, Tzu-hua; Jiang, Xinyi; Gibon, Emmanuel; Córdova, Luis A.; Loi, Florence; Lu, Laura; Jämsen, Eemeli; Egashira, Kensuke; Yang, Fan; Yao, Zhenyu; Goodman, Stuart B

2016-01-01

Wear particle-induced osteolysis limits the long-term survivorship of total joint replacement (TJR). Monocyte/macrophages are the key cells of this adverse reaction. Monocyte Chemoattractant Protein-1 (MCP-1/CCL2) is the most important chemokine regulating trafficking of monocyte/macrophages in particle-induced inflammation. 7ND recombinant protein is a mutant of CCL2 that inhibits CCL2 signaling. We have recently developed a layer-by-layer (LBL) coating platform on implant surfaces that can release biologically active 7ND. In this study, we investigated the effect of 7ND on wear particle-induced bone loss using the murine continuous polyethylene (PE) particle infusion model with 7ND coating of a titanium rod as a local drug delivery device. PE particles were infused into hollow titanium rods with or without 7ND coating implanted in the distal femur for 4 weeks. Specific groups were also injected with RAW 264.7 as the reporter macrophages. Wear particle-induced bone loss and the effects of 7ND were evaluated by microCT, immunohistochemical staining, and bioluminescence imaging. Local delivery of 7ND using the LBL coating decreased systemic macrophage recruitment, the number of osteoclasts and wear particle-induced bone loss. The development of a novel orthopaedic implant coating with anti-CCL2 protein may be a promising strategy to mitigate peri-prosthetic osteolysis. PMID:27918885

Lactation induces increases in the RANK/RANKL/OPG system in maxillary bone.

PubMed

Macari, Soraia; Sharma, Lavanya A; Wyatt, Amanda; da Silva, Janine Maíra; Dias, George J; Silva, Tarcília A; Szawka, Raphael E; Grattan, David R

2018-05-01

The underlying causes of maxillary bone loss during lactation remain poorly understood. We evaluated the impact of lactation on physiological and mechanically-induced alveolar bone remodeling. Nulliparous non-lactating (N-LAC) and 21-day lactating (LAC) mice underwent mechanically-induced bone remodeling by orthodontic tooth movement (OTM). Micro-computed tomography (microCT) was performed in the maxilla, femur and vertebra. Tartrate-resistant-acid phosphatase (TRAP) and Masson's trichrome labelling was performed in the maxillary bone and gene expression was determined in the periodontal ligament. The effect of prolactin on osteoclast (OCL) and osteoblast (OBL) differentiation was also investigated in N-LAC and LAC mice. Lactation increased alveolar bone loss in the maxilla, femur and vertebra, while OTM was enhanced. The number of OCL and OBL was higher in the maxilla of LAC mice. OTM increased OCL in both groups; while OBL was increased only in N-LAC but not in LAC mice, in which cell numbers were already elevated. The alveolar bone loss during lactation was associated with increased expression of receptor activator of nuclear factor-KappaB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in the maxilla. OTM induced the same responses in N-LAC mice, whereas it had no further effect in LAC mice. Lactation enhanced differentiation of OCL and OBL from bone marrow cells, and prolactin recapitulated OCL differentiation in N-LAC mice. Thus, lactation increases physiological maxillary bone remodeling and OTM, and both require activation of RANK/RANKL/OPG system. These findings expand our knowledge of lactation-induced osteopenia and have possible impact on clinical practice regarding orthodontic treatments and dental implants in lactating women. Copyright © 2018 Elsevier Inc. All rights reserved.

Antibody-based inhibition of circulating DLK1 protects from estrogen deficiency-induced bone loss in mice.

PubMed

Figeac, Florence; Andersen, Ditte C; Nipper Nielsen, Casper A; Ditzel, Nicholas; Sheikh, Søren P; Skjødt, Karsten; Kassem, Moustapha; Jensen, Charlotte H; Abdallah, Basem M

2018-05-01

Soluble delta-like 1 homolog (DLK1) is a circulating protein that belongs to the Notch/Serrate/delta family, which regulates many differentiation processes including osteogenesis and adipogenesis. We have previously demonstrated an inhibitory effect of DLK1 on bone mass via stimulation of bone resorption and inhibition of bone formation. Further, serum DLK1 levels are elevated and positively correlated to bone turnover markers in estrogen (E)-deficient rodents and women. In this report, we examined whether inhibition of serum DLK1 activity using a neutralizing monoclonal antibody protects from E deficiency-associated bone loss in mice. Thus, we generated mouse monoclonal anti-mouse DLK1 antibodies (MAb DLK1) that enabled us to reduce and also quantitate the levels of bioavailable serum DLK1 in vivo. Ovariectomized (ovx) mice were injected intraperitoneally twice weekly with MAb DLK1 over a period of one month. DEXA-, microCT scanning, and bone histomorphometric analyses were performed. Compared to controls, MAb DLK1 treated ovx mice were protected against ovx-induced bone loss, as revealed by significantly increased total bone mass (BMD) due to increased trabecular bone volume fraction (BV/TV) and inhibition of bone resorption. No significant changes were observed in total fat mass or in the number of bone marrow adipocytes. These results support the potential use of anti-DLK1 antibody therapy as a novel intervention to protect from E deficiency associated bone loss. Copyright © 2018 Elsevier Inc. All rights reserved.

The Effects of Cyclic Hydrostatic Pressure on Chondrogenesis and Viability of Human Adipose- and Bone Marrow-Derived Mesenchymal Stem Cells in Three-Dimensional Agarose Constructs

PubMed Central

Puetzer, Jennifer; Williams, John; Gillies, Allison; Bernacki, Susan

2013-01-01

This study investigates the effects of cyclic hydrostatic pressure (CHP) on chondrogenic differentiation of human adipose-derived stem cells (hASCs) in three-dimensional (3-D) agarose constructs maintained in a complete growth medium without soluble chondrogenic inducing factors. hASCs were seeded in 2% agarose hydrogels and exposed to 7.5 MPa CHP for 4 h per day at a frequency of 1 Hz for up to 21 days. On days 0, 7, 14, and 21, the expression levels of collagen II, Sox9, aggrecan, and cartilage oligomeric matrix protein (COMP) were examined by real-time reverse transcriptase–polymerase chain reaction analysis. Gene expression analysis found collagen II mRNA expression in only the CHP-loaded construct at day 14 and at no other time during the study. CHP-loaded hASCs exhibited upregulated mRNA expression of Sox9, aggrecan, and COMP at day 7 relative to unloaded controls, suggesting that CHP initiated chondrogenic differentiation of hASCs in a manner similar to human bone marrow-derived mesenchymal stem cells (hMSC). By day 14, however, loaded hASC constructs exhibited significantly lower mRNA expression of the chondrogenic markers than unloaded controls. Additionally, by day 21, the samples exhibited little measurable mRNA expression at all, suggesting a decreased viability. Histological analysis validated the lack of mRNA expression at day 21 for both the loaded and unloaded control samples with a visible decrease in the cell number and change in morphology. A comparative study with hASCs and hMSCs further examined long-term cell viability in 3-D agarose constructs of both cell types. Decreased cell metabolic activity was observed throughout the 21-day experimental period in both the CHP-loaded and control constructs of both hMSCs and hASCs, suggesting a decrease in cell metabolic activity, alluding to a decrease in cell viability. This suggests that a 2% agarose hydrogel may not optimally support hASC or hMSC viability in a complete growth medium in the absence of soluble chondrogenic inducing factors over long culture durations. This is the first study to examine the ability of mechanical stimuli alone, in the absence of chondrogenic factors transforming growth factor beta (TGF-β)3, TGF-β1 and/or bone morphogenetic protein 6 (BMP6) to induce hASC chondrogenic differentiation. The findings of this study suggest that CHP initiates hASC chondrogenic differentiation, even in the absence of soluble chondrogenic inductive factors, confirming the importance of considering both mechanical stimuli and appropriate 3-D culture for cartilage tissue engineering using hASCs. PMID:22871265

Radiographic evidence of disuse osteoporosis in the monkey /M. nemestrina/

NASA Technical Reports Server (NTRS)

Young, D. R.; Schneider, V. S.

1981-01-01

Radiological techniques were utilized for monitoring progressive changes in compact bone in the tibia of monkeys during experimentally induced osteopenia. Bone mass loss in the tibia during restraint was evaluated from radiographs, from bone mineral analysis, and from images reconstructed from gamma ray computerized tomography. The losses during 6 months of restraint tended to occur predominantly in the proximal tibia and were characterized by subperiosteal bone loss, intracortical striations, and scalloped endosteal surfaces. Bone mineral content in the cross section of the tibia declined 17-21%. In 6 months of recovery, the mineral content of the proximal tibia remained depressed.

Role of Growth Hormone, Exercise and Serum Phosphorus in Unloaded Bone of Young Rats

NASA Technical Reports Server (NTRS)

Arnnaud, Sara B.; Harper, J. S.; Gosselink, K. L.; Navidi, M.; Fung, P.; Grindeland, R. E.; Wade, Charles E. (Technical Monitor)

1994-01-01

Growth hormone, known to be stimulated by exercise, is suppressed in rats after space flight and in a ground-based model in which the hind-limbs are unloaded (S). To determine the role of GH in the osteopenia of unloaded bones of S rats, young males were treated with GH combined with insulin-like growth factor-1 (IGF-1), a peptide that mediates the local actions of the hormone. 200 g rats, hypophysectomized (hypox) 17 d earlier, were treated with 1 mg/kg/d GH/IGF-1 (H) or saline (C) in 3 divided daily doses x10 d. Hind-limb bones were unloaded (S), ambulated (A) or exercised (X) by climbing a ladder while carrying a weight. Growth was monitored daily. Tibial growth plate (Tepi) was measured with a micrometer, and femoral (F) area, length, and mineral content (BMC) by DEXA. Parameters of calcium metabolism were measured by autoanalyzer and calciotropic hormones by radioimmunoassay. F bone density, g/square cm, (BMD) or BW were not affected by S in Hypox. However, FBMD was lower in S+H than A+H (p is less than 0.002) and H stimulated whole body growth in S (5.2 g/d) and SX (5.6 g/d) to a lesser extent than in A (6.6 g/d) (p is less than 0.05). Adjusted for BW, Tepi showed the greatest increase in S+H+X (64%), the next highest increase in S+H (50%) and no change in S+X. F area, length and BMC/100 g BW were lower in all H groups than respective C's. By multiple regression analysis, serum phosphorus (Pi) which correlated with Tepi (r = 0.88, p is less than 0.001) and was inversely related to FBMC (r = -0.68, p is less than 0.001) proved to be the most significant determinant of BMC. This illustrates the dependence of osteopenia in S on GH, the maximizing effect of X for epiphyseal growth and the major role of Pi metabolism on BMC in weight bearing bone during growth.

Efficacy of anti-IL-23 monotherapy versus combination therapy with anti-IL-17 in estrogen deficiency induced bone loss conditions.

PubMed

Shukla, Priyanka; Mansoori, Mohd Nizam; Singh, Divya

2018-05-01

Recent studies have identified that Interleukin (IL)-23/IL-17 axis plays crucial role in pathogenesis of inflammation and bone destruction. IL-23 is thought to promote joint destruction in arthritis by stimulating Th17 cells. IL-23 directly mediates bone loss by inducing osteoclastogenesis and receptor activator of kappa B ligand (RANKL) expression in T cells. IL-23 also promotes tartrate-resistant acid phosphatase (TRAP) activity of osteoclast in osteoblast-osteoclast co-culture. The role of IL-23 has not been studied in estrogen deficiency induced bone loss. Here, we study the effect of IL-23 neutralization in ovariectomized (Ovx) estrogen deficient mice on various immune and skeletal parameters. We also determine whether the combination of anti-IL-23 and anti-IL17 has enhanced osteoprotective effects compared to monotherapies. Treatment of anti-IL-23 and its combination with anti-IL-17 suppressed Th17 cell differentiation and promoted development of T regulatory cells. Anti-IL-23 and its combination with anti-IL-17 prevented bone loss. However, the individual monotherapies of anti-IL-23 and anti-IL-17 were more effective than combination therapy. Treatment of IL-17 and IL-23 cytokines to bone marrow stromal cells led to increased differentiation towards osteoblast lineage. Double neutralization of IL-23 and IL-17 might be inhibiting this phenomenon thus producing less potent effects. Our studies thus support bone protective effects of anti-IL-23 and that the monotherapies of neutralizing antibodies against IL-17 and IL-23 may be a more accepted mode of treatment in management of post-menopausal bone loss rather than combination therapy. Copyright © 2018 Elsevier Inc. All rights reserved.

Melanocortin agonism as a viable strategy to control alveolar bone loss induced by oral infection.

PubMed

Madeira, Mila F M; Queiroz-Junior, Celso M; Montero-Melendez, Trinidad; Werneck, Silvia M C; Corrêa, Jôice D; Soriani, Frederico M; Garlet, Gustavo P; Souza, Daniele G; Teixeira, Mauro M; Silva, Tarcilia A; Perretti, Mauro

2016-12-01

Alveolar bone loss is a result of an aggressive form of periodontal disease (PD) associated with Aggregatibacter actinomycetemcomitans (Aa) infection. PD is often observed with other systemic inflammatory conditions, including arthritis. Melanocortin peptides activate specific receptors to exert antiarthritic properties, avoiding excessing inflammation and modulating macrophage function. Recent work has indicated that melanocortin can control osteoclast development and function, but whether such protection takes place in infection-induced alveolar bone loss has not been investigated. The purpose of this study was to evaluate the role of melanocortin in Aa-induced PD. Mice were orally infected with Aa and treated with the melanocortin analog DTrp 8 -γMSH or vehicle daily for 30 d. Then, periodontal tissue was collected and analyzed. Aa-infected mice treated with DTrp 8 -γMSH presented decreased alveolar bone loss and a lower degree of neutrophil infiltration in the periodontium than vehicle-treated animals; these actions were associated with reduced periodontal levels of TNF-α, IFN-γ, and IL-17A. In vitro experiments with cells differentiated into osteoclasts showed that osteoclast formation and resorptive activity were attenuated after treatment with DTrp 8 -γMSH. Thus, melanocortin agonism could represent an innovative way to tame overexuberant inflammation and, at the same time, preserve bone physiology, as seen after Aa infection.-Madeira, M. F. M., Queiroz-Junior, C. M., Montero-Melendez, T., Werneck, S. M. C., Corrêa, J. D., Soriani, F. M., Garlet, G. P., Souza, D. G., Teixeira, M. M., Silva, T. A., Perretti, M. Melanocortin agonism as a viable strategy to control alveolar bone loss induced by oral infection. © FASEB.

Evaluation in a Dog Model of Three Antimicrobial Glassy Coatings: Prevention of Bone Loss around Implants and Microbial Assessments.

PubMed

López-Píriz, Roberto; Solá-Linares, Eva; Rodriguez-Portugal, Mercedes; Malpica, Beatriz; Díaz-Güemes, Idoia; Enciso, Silvia; Esteban-Tejeda, Leticia; Cabal, Belén; Granizo, Juan José; Moya, José Serafín; Torrecillas, Ramón

2015-01-01

The aim of the present study is to evaluate, in a ligature-induced peri-implantitis model, the efficacy of three antimicrobial glassy coatings in the prevention of biofilm formation, intrasulcular bacterial growth and the resulting peri-implant bone loss. Mandibular premolars were bilaterally extracted from five beagle dogs. Four dental implants were inserted on each hemiarch. Eight weeks after, one control zirconia abutment and three with different bactericidal coatings (G1n-Ag, ZnO35, G3) were connected. After a plaque control period, bacterial accumulation was allowed and biofilm formation on abutments was observed by Scanning Electron Microscopy (SEM). Peri-implantitis was induced by cotton ligatures. Microbial samples and peri-implant crestal bone levels of all implant sites were obtained before, during and after the breakdown period. During experimental induce peri-implantitis: colony forming units counts from intrasulcular microbial samples at implants with G1n-Ag coated abutment remained close to the basal inoculum; G3 and ZnO35 coatings showed similar low counts; and anaerobic bacterias counts at control abutments exhibited a logarithmic increase by more than 2. Bone loss during passive breakdown period was no statistically significant. Additional bone loss occurred during ligature-induce breakdown: 0.71 (SD 0.48) at G3 coating, 0.57 (SD 0.36) at ZnO35 coating, 0.74 (SD 0.47) at G1n-Ag coating, and 1.29 (SD 0.45) at control abutments; and statistically significant differences (p<0.001) were found. The lowest bone loss at the end of the experiment was exhibited by implants dressing G3 coated abutments (mean 2.1; SD 0.42). Antimicrobial glassy coatings could be a useful tool to ward off, diminish or delay peri-implantitis progression.

The TCAR Report: Translational Cell and Animal Research Space (1965-2011) Sponsored by NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Ronca, A. E.; Mains, Richard; Alwood, J. S.; French, A. J.; Smith, J. D.; Miller, Virginia; Tash, Joseph; Jenkins, Marjorie

2015-01-01

Five decades ago, NASA Ames Research Center (ARC) began a vigorous program of space biology research utilizing animal cells, tissues and whole organisms. Since its inception, this program has yielded exciting new insights into how spaceflight influences fundamental processes of living systems. These are findings with important translational implications for human health in space and on Earth. The TCAR Report is a compilation of 394 flight experiments conducted across the period spanning 1965 - 2011 with individual chapters devoted to: (1) Bone Physiology, (2) Cardiovascular/Cardiopulmonary Physiology, (3) Developmental Biology, (4) Immunology, (5) Microbial Growth and Virulence, (6) Muscle Physiology, (7) Neurophysiology and (8) Regulatory Physiology. Specialists in those disciplines reviewed the research and each prepared an overview including the translational relevance of the findings for human health in space and on Earth. The Report will be made available in early 2015 through standard NASA publication resources and on the NASA Life Sciences Data Archive (http://lsda.jsc.nasa.gov/lsda_home1.aspx). The LSDA can be mined for detailed information, including Experiment, Mission, Available Biospecimens, Document, Hardware, Dataset, Personnel, and includes a searchable Photo Gallery. Space biology translational topic highlights include: Inflight centrifugation protection of bone strength losses; Assessment of evidence related to visual impairment in astronauts; Mammalian development including vestibular system plasticity and vestibular-visual integration; Verification of limb unloading ground-based studies as a model for spaceflight unloading; Immune system impairment and increased microbiological virulence aligned with immune dysfunction; and Rapid bone and muscle tissue and functional losses associated with unloading. In addition to astronauts, these results may help humans on Earth, by providing insight into the definition of fundamental mechanisms and potential treatments for debilitating changes that result from human aging and disease. The TCAR effort has resulted in significant new insights. Modern tools now widely available for "Omics" research with model organisms and humans provide new opportunities for translational research. Omics research at various levels is greatly complemented by studies at the tissue and organismal levels. Key discoveries can occur at either the basic research or the health surveillance level such as vision problems observed in astronauts stimulating studies of eye tissues in rodents that identified relevant changes. The Ames Biospecimen Sharing Program (BSP), serving the NASA Space Biology and HRP programs, was created to maximize utilization and scientific return from unique animal specimens derived from rare, complex and costly NASA spaceflight and ground-based analog experiments. The BSP is a valuable tool for advancing translational science at NASA. Dynamic methods for tracking translational linkages across NASA space life sciences and medicine are strongly encouraged for translational science.

Osteoclast TGF-β Receptor Signaling Induces Wnt1 Secretion and Couples Bone Resorption to Bone Formation

PubMed Central

Weivoda, Megan M; Ruan, Ming; Pederson, Larry; Hachfeld, Christine; Davey, Rachel A; Zajac, Jeffrey D; Westendorf, Jennifer J; Khosla, Sundeep; Oursler, Merry Jo

2016-01-01

Osteoblast-mediated bone formation is coupled to osteoclast-mediated bone resorption. These processes become uncoupled with age, leading to increased risk for debilitating fractures. Therefore, understanding how osteoblasts are recruited to sites of resorption is vital to treating age-related bone loss. Osteoclasts release and activate TGF-β from the bone matrix. Here we show that osteoclastspecific inhibition of TGF-β receptor signaling in mice results in osteopenia due to reduced osteoblast numbers with no significant impact on osteoclast numbers or activity. TGF-β induced osteoclast expression of Wnt1, a protein crucial to normal bone formation, and this response was blocked by impaired TGF-β receptor signaling. Osteoclasts in aged murine bones had lower TGF-β signaling and Wnt1 expression in vivo. Ex vivo stimulation of osteoclasts derived from young or old mouse bone marrow macrophages showed no difference in TGF-β–induced Wnt1 expression. However, young osteoclasts expressed reduced Wnt1 when cultured on aged mouse bone chips compared to young mouse bone chips, consistent with decreased skeletal TGF-β availability with age. Therefore, osteoclast responses to TGF-β are essential for coupling bone resorption to bone formation, and modulating this pathway may provide opportunities to treat age-related bone loss. PMID:26108893

Induced Pluripotent Stem Cell Derived Mesenchymal Stem Cells for Attenuating Age-Related Bone Loss

DTIC Science & Technology

2012-07-01

Mesenchymal stem cell (MSC) differentiation towards the bone forming osteoblastic lineage decreases as a function of age and may contribute to age-related...problem of age-related reduced availability of MSC we propose to examine the bone anabolic potential of induced pluripotent stem cell (iPS) derived MSC

Creep of trabecular bone from the human proximal tibia

PubMed Central

Novitskaya, Ekaterina; Zin, Carolyn; Chang, Neil; Cory, Esther; Chen, Peter; D'Lima, Darryl; Sah, Robert L.; McKittrick, Joanna

2014-01-01

Creep is the deformation that occurs under a prolonged, sustained load and can lead to permanent damage in bone. Creep in bone is a complex phenomenon and varies with type of loading and local mechanical properties. Human trabecular bone samples from proximal tibia were harvested from a 71-year old female cadaver with osteoporosis. The samples were initially subjected to one cycle load up to 1% strain to determine the creep load. Samples were then loaded in compression under a constant stress for two hours and immediately unloaded. All tests were conducted with the specimens soaked in phosphate buffered saline with proteinase inhibitors at 37°C. Steady state creep rate and final creep strain were estimated from mechanical testing and compared with published data. The steady state creep rate correlated well with values obtained from bovine tibial and human vertebral trabecular bone, and was higher for lower density samples. Tissue architecture was analyzed by micro-computed tomography (μCT) both before and after creep testing to assess creep deformation and damage accumulated. Quantitative morphometric analysis indicated that creep induced changes in trabecular separation and the structural model index. A main mode of deformation was bending of trabeculae. PMID:24857486

Modulation of bone remodeling via mechanically activated ion channels

NASA Technical Reports Server (NTRS)

Duncan, Randall L. (Principal Investigator)

1996-01-01

A critical factor in the maintenance of bone mass is the physical forces imposed upon the skeleton. Removal of these forces, such as in a weightless environment, results in a rapid loss of bone, whereas application of exogenous mechanical strain has been shown to increase bone formation. Numerous flight and ground-based experiments indicate that the osteoblast is the key bone cell influenced by mechanical stimulation. Aside from early transient fluctuations in response to unloading, osteoclast number and activity seem unaffected by removal of strain. However, bone formation is drastically reduced in weightlessness and osteoblasts respond to mechanical strain with an increase in the activity of a number of second messenger pathways resulting in increased anabolic activity. Unfortunately, the mechanism by which the osteoblast converts physical stimuli into a biochemical message, a process we have termed biochemical coupling, remains elusive. Prior to the application of this grant, we had characterized a mechanosensitive, cation nonselective channel (SA-cat) in osteoblast-like osteosarcoma cells that we proposed is the initial signalling mechanism for mechanotransduction. During the execution of this grant, we have made considerable progress to further characterize this channel as well as to determine its role in the osteoblastic response to mechanical strain. To achieve these goals, we combined electrophysiologic techniques with cellular and molecular biology methods to examine the role of these channels in the normal function of the osteoblast in vitro.

Core Research Program, Year 5

NASA Technical Reports Server (NTRS)

2002-01-01

Dramatic losses of bone mineral density (BMD) and muscle strength are two of the best documented changes observed in humans after prolonged exposure to microgravity. Recovery of muscle upon return to a 1-G environment is well studied, however, far less is known about the rate and completeness of BMD recovery to pre-flight values. Using the mature tail-suspended adult rat model, this proposal will focus on the temporal course of recovery in tibial bone following a 28-d period of skeletal unloading. Through the study of bone density and muscle strength in the same animal, time-points during recovery from simulated microgravity will be identified when bone is at an elevated risk for fracture. These will occur due to the rapid recovery of muscle strength coupled with a slower recovery of bone, producing a significant mismatch in functional strength of these two tissues. Once the time-point of maximal mismatch is defined, various mechanical and pharmacological interventions will be tested at and around this time-point in attempt to minimize the functional difference of bone and muscle. The outcomes of this research will have high relevance for optimizing the rehabilitation of astronauts upon return to Earth, as well as upon landing on the Martian surface before assuming arduous physical tasks. Further. it will impact significantly on rehabilitation issues common to patients experiencing long periods of limb immobilization or bed rest.

Calf Strength Loss During Mechanical Unloading: Does It Matter?

NASA Technical Reports Server (NTRS)

English, K. L.; Mulavara, A.; Bloomberg, J.; Ploutz-Snyder, LL

2016-01-01

During the mechanical unloading of spaceflight and its ground-based analogs, muscle mass and muscle strength of the calf are difficult to preserve despite exercise countermeasures that effectively protect these parameters in the thigh. It is unclear what effects these local losses have on balance and whole body function which will be essential for successful performance of demanding tasks during future exploration missions.

The effect of an inhibitor of gut serotonin (LP533401) during the induction of periodontal disease.

PubMed

Lima, G M G; Corazza, B J M; Moraes, R M; de Oliveira, F E; de Oliveira, L D; Franco, G C N; Perrien, D S; Elefteriou, F; Anbinder, A L

2016-10-01

LP533401 is an inhibitor of tryptophan hydroxylase 1, which regulates serotonin production in the gut. Previous work indicates that LP533401 has an anabolic effect in bone. Thus, we hypothesized that inhibition of gut serotonin production may modulate the host response in periodontal disease. In this study, we aimed to analyze the effects of LP533401 in a rat periodontitis model to evaluate the role of gut serotonin in periodontitis pathophysiology. Twenty-four rats were divided into three groups: treated group (T: ligature-induced periodontal disease and LP533401, 25 mg/kg/d) by gavage; ligature group (L: ligature-induced periodontal disease only); and control group (C: without ligature-induced periodontal disease). After 28 d, radiographic alveolar bone support was measured on digital radiographs, and alveolar bone volume fraction, tissue mineral density and trabeculae characteristics were quantified by microcomputed tomography in the right hemi-mandible. Left hemi-mandibles were decalcified and alveolar bone loss, attachment loss and area of collagen in the gingiva were histologically analyzed. Significant difference between the L and C groups was found, confirming that periodontal disease was induced. We observed no difference between the T and L groups regarding alveolar bone destruction and area of collagen. LP533401 (25 mg/kg/d) for 28 d does not prevent bone loss and does not modulate host response in a rat model of induced periodontal disease. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Protective effect of Rhizoma Dioscoreae extract against alveolar bone loss in ovariectomized rats via regulation of IL-6/STAT3 signaling.

PubMed

Zhang, Zhi-Guo; Chen, Yan-Jing; Xiang, Li-Hua; Pan, Jing-Hua; Wang, Zhen; Xiao, Gary Guishan; Ju, Da-Hong

2017-11-01

The aim of the present study was to assess the effectiveness of Rhizoma Dioscoreae extract (RDE) on preventing rat alveolar bone loss induced by ovariectomy (OVX), and to determine the role of interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in this effect. Female Wistar rats were subjected to OVX or sham surgery. The rats that had undergone OVX were treated with RDE (RDE group), vehicle (OVX group) or 17β-estradiol subcutaneous injection (E2 group). Subsequently, bone metabolic activity was assessed by analyzing 3-D alveolar bone construction, bone mineral density, as well as the plasma biomarkers of bone turnover. The gene expression of alveolar bone in the OVX and RDE groups was evaluated by IL-6/STAT3 signaling pathway polymerase chain reaction (PCR) arrays, and differentially expressed genes were determined through reverse transcription-quantitative PCR. The inhibitory effect of RDE on alveolar bone loss in the OVX group was demonstrated in the study. In comparison with the OVX group, the RDE group exhibited 19 downregulated genes and 1 upregulated gene associated with the IL-6/STAT3 signaling pathway in alveolar bone. Thus, RDE was shown to relieve OVX-induced alveolar bone loss in rats, an effect which was likely associated with decreased abnormal bone remodeling via regulation of the IL-6/STAT3 signaling pathway.

Role of WNT16 in the Regulation of Periosteal Bone Formation in Female Mice

PubMed Central

Wergedal, Jon E.; Kesavan, Chandrasekhar; Brommage, Robert; Das, Subhashri

2015-01-01

In this study, we evaluated the role of WNT16 in regulating bone size, an important determinant of bone strength. Mice with targeted disruption of the Wnt16 gene exhibited a 24% reduction in tibia cross-sectional area at 12 weeks of age compared with that of littermate wild-type (WT) mice. Histomorphometric studies revealed that the periosteal bone formation rate and mineral apposition rate were reduced (P < .05) by 55% and 32%, respectively, in Wnt16 knockout (KO) vs WT mice at 12 weeks of age. In contrast, the periosteal tartrate resistant acid phosphatase-labeled surface was increased by 20% in the KO mice. Because mechanical strain is an important physiological regulator of periosteal bone formation (BF), we determined whether mechanical loading–induced periosteal BF is compromised in Wnt16 KO mice. Application of 4800-μe strain to the right tibia using a 4-point bending loading method for 2 weeks (2-Hz frequency, 36 cycles per day, 6 days/wk) produced a significant increase in cross-sectional area (11% above that of the unloaded left tibia, P < .05, n = 6) in the WT but not in the KO mice (−0.2% change). Histomorphometric analyses revealed increases in the periosteal bone formation rate and mineral apposition rate in the loaded bones of WT but not KO mice. Wnt16 KO mice showed significant (20%–70%) reductions in the expression levels of markers of canonical (β-catenin and Axin2) but not noncanonical (Nfatc1 and Tnnt2) WNT signaling in the periosteum at 5 weeks of age. Our findings suggest that WNT16 acting via canonical WNT signaling regulates mechanical strain-induced periosteal BF and bone size. PMID:25521583

Tissue Specific Expression Of Sprouty1 In Mice Protects Against High Fat Diet Induced Fat Accumulation, Bone Loss, And Metabolic Dysfunction

PubMed Central

Urs, Sumithra; Henderson, Terry; Le, Phuong; Rosen, Clifford J.; Liaw, Lucy

2012-01-01

We recently characterized Sprouty1 (Spry1), a growth factor signaling inhibitor as a regulator of marrow progenitor cells promoting osteoblast differentiation at the expense of adipocytes. Adipose tissue specific Spry1 expression in mice resulted in increased bone mass and reduced body fat while conditional knockout of Spry1 had the opposite effect with decreased bone and increased body fat. Because Spry1 suppresses normal fat development, we tested the hypothesis that Spry1 expression prevents high fat diet-induced obesity, bone loss, and associated lipid abnormalities and demonstrate that Spry1 has a long-term protective effect on mice fed a high caloric diet. We studied diet-induced obesity in mice with fatty acid binding promoter (aP2)-driven expression or conditional knockout of Spry1 in adipocytes. Phenotyping was performed by whole body dual-energy X-ray absorptiometry, microCT, histology and blood analysis. In conditional Spry1 null mice, high fat diet increased body fat by 40%, impaired glucose regulation, and led to liver steatosis. However, over-expression of Spry1 led to 35% lower body fat, reduced bone loss, and normal metabolic function compared to single transgenics. This protective phenotype was associated with decreased circulating insulin (70%) and leptin (54%) compared to controls on a high fat diet. Additionally, Spry1 expression decreased adipose tissue inflammation by 45%. We show that conditional Spry1 expression in adipose tissue protects against high fat diet-induced obesity and associated bone loss. PMID:22142492

Tissue-specific expression of Sprouty1 in mice protects against high-fat diet-induced fat accumulation, bone loss and metabolic dysfunction.

PubMed

Urs, Sumithra; Henderson, Terry; Le, Phuong; Rosen, Clifford J; Liaw, Lucy

2012-09-28

We recently characterised Sprouty1 (Spry1), a growth factor signalling inhibitor as a regulator of marrow progenitor cells promoting osteoblast differentiation at the expense of adipocytes. Adipose tissue-specific Spry1 expression in mice resulted in increased bone mass and reduced body fat, while conditional knockout of Spry1 had the opposite effect with decreased bone mass and increased body fat. Because Spry1 suppresses normal fat development, we tested the hypothesis that Spry1 expression prevents high-fat diet-induced obesity, bone loss and associated lipid abnormalities, and demonstrate that Spry1 has a long-term protective effect on mice fed a high-energy diet. We studied diet-induced obesity in mice with fatty acid binding promoter-driven expression or conditional knockout of Spry1 in adipocytes. Phenotyping was performed by whole-body dual-energy X-ray absorptiometry, microCT, histology and blood analysis. In conditional Spry1-null mice, a high-fat diet increased body fat by 40 %, impaired glucose regulation and led to liver steatosis. However, overexpression of Spry1 led to 35 % (P < 0·05) lower body fat, reduced bone loss and normal metabolic function compared with single transgenics. This protective phenotype was associated with decreased circulating insulin (70 %) and leptin (54 %; P < 0·005) compared with controls on a high-fat diet. Additionally, Spry1 expression decreased adipose tissue inflammation by 45 %. We show that conditional Spry1 expression in adipose tissue protects against high-fat diet-induced obesity and associated bone loss.

Gravitational Biology: The Rat Model

NASA Technical Reports Server (NTRS)

1997-01-01

In this session, Session JP3, the discussion focuses on the following topics: Morphology of brain, pituitary and thyroid in the rats exposed to altered gravity; Biochemical Properties of B Adrenoceptors After Spaceflight (LMS-STS78) or Hindlimb Suspension in Rats; Influence of Hypergravity on the Development of Monoaminergic Systems in the Rat Spinal Cord; A Vestibular Evoked Potentials (VsEPs) Study of the Function of the Otolith Organs in Different Head Orientations with respect to Earth Gravity Vector in the Rat; Quantitative Observations on the Structure of Selected Proprioceptive Components in Adult Rats that Underwent About Half of their Fetal Development in Space; Effects of a Nine-Day Shuttle Mission on the Development of the Neonatal Rat Nervous System, A Behavioral Study; Muscle Atrophy Associated to Microgravity in Rat, Basic Data For Countermeasures; Simulated Weightlessness by Unloading in the Rat, Results of a Time Course Study of Biochemical Events Occurring During Unloading and Lack of Effect of a rhBNP-2 Treatment on Bone Formation and Bone Mineral Content in Unloading Rats; and Cytological Mechanism of the Osteogenesis Under Microgravity Conditions.

Clomipramine counteracts lipid raft disturbance due to short-term muscle disuse.

PubMed

Bryndina, Irina G; Shalagina, Maria N; Sekunov, Alexey V; Zefirov, Andrei L; Petrov, Alexey M

2018-01-18

Disuse-induced skeletal muscle dysfunction is a serious consequence of long-term spaceflight, numerous diseases and conditions for which treatment possibilities are still strictly limited. We have previously shown that acute hindlimb suspension (HS)-mediated disuse disrupts membrane lipid rafts in the unloaded muscle. Here, we investigated whether pretreatment of rats with the inhibitor of acid sphingomyelinase, clomipramine (1.25mg/g/day, intramuscularly, for 5days before HS), is able to hinder the loss in lipid raft integrity in response to 12h of HS. Clomipramine pretreatment significantly counteracted the decrease in labeling of the plasma membranes with lipid raft markers (fluorescent cholera toxin B subunit and bodipy-GM1-ganglioside) specifically in the junctional regions of the suspended soleus muscle. This was associated with: a) enhancing raft disrupting potential of exogenous sphingomyelinase in the junctional membranes; b) prevention of both ceramide accumulation and cholesterol loss; c) prevention of decline in nicotinic acetylcholine receptor labeling in the unloaded muscle. Our data suggest that sphingomyelinase-mediated raft disturbance serves as one of the earlier events in HS effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevention and treatment of glucocorticoid-induced osteoporosis: a comparison of calcitriol, vitamin D plus calcium, and alendronate plus calcium.

PubMed

Sambrook, Philip N; Kotowicz, Mark; Nash, Peter; Styles, Colin B; Naganathan, Vasi; Henderson-Briffa, Kathy N; Eisman, John A; Nicholson, Geoff C

2003-05-01

High-dose corticosteroids, used for many medical conditions, are associated with rapid bone loss from sites such as the vertebrae, and compression fractures can be observed within months. Recent trials suggest treatment with bisphosphonates or active vitamin D analogs can reduce bone loss and the risk of fracture associated with glucocorticoids, but few studies have directly compared such agents. We conducted a randomized, multicenter, open-label trial to compare the efficacy of alendronate, calcitriol, and simple vitamin D in prevention and treatment of glucocorticoid-induced bone loss. A total of 195 subjects (134 females and 61 males) commencing or already taking glucocorticoids were randomized to one of three groups: calcitriol, 0.5 to 0.75 microg/day; simple vitamin D (ergocalciferol, 30,000 IU weekly) plus calcium carbonate (600 mg daily); or alendronate, 10 mg/day plus calcium carbonate (600 mg daily). Over 2 years, mean lumbar bone mineral density change was +5.9% with alendronate, -0.5% with ergocalciferol, and -0.7% with calcitriol (p < 0.001). At the femoral neck, there was no significant difference in bone mineral density change between the treatments over 2 years: alendronate (+0.9%), ergocalciferol (-3.2%), and calcitriol (-2.2%). Lumbar bone loss varied according to whether patients were starting or receiving chronic glucocorticoids, and there was a significant treatment x prior glucocorticoid use interaction effect. Six of 66 calcitriol subjects, 1 of 61 ergocalciferol subjects, and 0 of 64 alendronate subjects sustained new vertebral fractures. These data do not suggest any difference between simple vitamin D and calcitriol but do show that alendronate was superior to either treatment for glucocorticoid induced bone loss.

Methoxyisoflavones formononetin and isoformononetin inhibit the differentiation of Th17 cells and B-cell lymphopoesis to promote osteogenesis in estrogen-deficient bone loss conditions.

PubMed

Mansoori, Mohd N; Tyagi, Abdul M; Shukla, Priyanka; Srivastava, Kamini; Dev, Kapil; Chillara, Raju; Maurya, Rakesh; Singh, Divya

2016-05-01

Recent studies have shown that immune system plays a major role in pathophysiology of postmenopausal osteoporosis. Previously we have shown that phytoestrogens like daidzein and medicarpin exhibit immunoprotective effects, by virtue of which they alleviate bone loss. With this background, methoxyisoflavones like formononetin (formo) and isoformononetin (isoformo) that have been studied for preventing bone loss in ovariectomized rats were tested for their immunomodulatory effects in estrogen-deficient bone loss mice model. Adult Balb/c mice (N = 8/group) were given oral dose of formo and isoformo at 10 mg/kg body weight, post ovariectomy (Ovx) daily for 6 weeks. Animals were autopsied and long bones were harvested to study bone microarchitecture. Peripheral blood mononuclear cells were isolated for fluorescence-activated cell sorting and RNA analysis. Serum was collected for enzyme-linked immunosorbent assay. It was observed that formo and isoformo treatment to Ovx mice led to significant restoration of Ovx-induced deterioration of trabecular microarchitecture. Pro-osteoclastogenic subset Th17 and B cells were decreased in formo/isoformo-treated Ovx mice in comparison with vehicle-treated Ovx group. Formo and isoformo treatment to Ovx mice also led to decreased expression of Th17 diffentiation factors and promoted T-regulatory cell differentiation. Formo was more effective in enhancing the FOXP3 expression compared with isoformo. IL-17A-induced osteoclastogenesis and inhibition of osteoblast apoptosis were also suppressed by formo and isoformo treatment, with formo having a more potent effect. Our study demonstrates the immunomodulatory activity of methoxyisoflavones, formo, and isoformo, which translate into improved skeletal parameters, thereby preventing Ovx-induced bone loss.

Irradiation by pulsed Nd:YAG laser induces the production of extracellular matrix molecules by cells of the connective tissues: a tool for tissue repair

NASA Astrophysics Data System (ADS)

Monici, Monica; Basile, Venere; Cialdai, Francesca; Romano, Giovanni; Fusi, Franco; Conti, Antonio

2008-04-01

Many studies demonstrated that mechanical stress is a key factor for tissue homeostasis, while unloading induce loss of mass and impairment of function. Because of their physiological function, muscle, connective tissue, bone and cartilage dynamically interact with mechanical and gravitational stress, modifying their properties through the continuous modification of their composition. Indeed, it is known that mechanical stress increases the production of extracellular matrix (ECM) components by cells, but the mechanotransduction mechanisms and the optimal loading conditions required for an optimal tissue homeostasis are still unknown. Considering the importance of cell activation and ECM production in tissue regeneration, a proper use of mechanical stimulation could be a powerful tool in tissue repair and tissue engineering. Studies exploring advanced modalities for supplying mechanical stimuli are needed to increase our knowledge on mechanobiology and to develop effective clinical applications. Here we describe the effect of photomechanical stress, supplied by a pulsed Nd:YAG laser on ECM production by cells of connective tissues. Cell morphology, production of ECM molecules (collagens, fibronectin, mucopolysaccharides), cell adhesion and cell energy metabolism have been studied by using immunofluorescence and autofluorescence microscopy. The results show that photomechanical stress induces cytoskeleton remodelling, redistribution of membrane integrins, increase in production of ECM molecules. These results could be of consequence for developing clinical protocols for the treatment of connective tissue dideases by pulsed Nd:YAG laser.

Transgenic Mouse Model for Reducing Oxidative Damage in Bone

NASA Technical Reports Server (NTRS)

Schreurs, A.-S.; Torres, S.; Truong, T.; Kumar, A.; Alwood, J. S.; Limoli, C. L.; Globus, R. K.

2014-01-01

Exposure to musculoskeletal disuse and radiation result in bone loss; we hypothesized that these catabolic treatments cause excess reactive oxygen species (ROS), and thereby alter the tight balance between bone resorption by osteoclasts and bone formation by osteoblasts, culminating in bone loss. To test this, we used transgenic mice which over-express the human gene for catalase, targeted to mitochondria (MCAT). Catalase is an anti-oxidant that converts the ROS hydrogen peroxide into water and oxygen. MCAT mice were shown previously to display reduced mitochondrial oxidative stress and radiosensitivity of the CNS compared to wild type controls (WT). As expected, MCAT mice expressed the transgene in skeletal tissue, and in marrow-derived osteoblasts and osteoclast precursors cultured ex vivo, and also showed greater catalase activity compared to wildtype (WT) mice (3-6 fold). Colony expansion in marrow cells cultured under osteoblastogenic conditions was 2-fold greater in the MCAT mice compared to WT mice, while the extent of mineralization was unaffected. MCAT mice had slightly longer tibiae than WT mice (2%, P less than 0.01), although cortical bone area was slightly lower in MCAT mice than WT mice (10%, p=0.09). To challenge the skeletal system, mice were treated by exposure to combined disuse (2 wk Hindlimb Unloading) and total body irradiation Cs(137) (2 Gy, 0.8 Gy/min), then bone parameters were analyzed by 2-factor ANOVA to detect possible interaction effects. Treatment caused a 2-fold increase (p=0.015) in malondialdehyde levels of bone tissue (ELISA) in WT mice, but had no effect in MCAT mice. These findings indicate that the transgene conferred protection from oxidative damage caused by treatment. Unexpected differences between WT and MCAT mice emerged in skeletal responses to treatment.. In WT mice, treatment did not alter osteoblastogenesis, cortical bone area, moment of inertia, or bone perimeter, whereas in MCAT mice, treatment increased these parameters. Taken together, this typically catabolic treatment (disuse and irradiation) appeared to stimulate cortical expansion in MCAT mice but not WT mice. In conclusion, these results reveal the importance of mitochondrial ROS generation in skeletal remodeling and show that MCAT mice provide a useful animal model for bone studies.

Synergistic effects of green tea polyphenols and alphacalcidol on chronic inflammation-induced bone loss in female rats

PubMed Central

Yeh, J. K.; Cao, J. J.; Tatum, O. L.; Dagda, R. Y.; Wang, J.-S.

2010-01-01

Summary Studies suggest that green tea polyphenols (GTP) or alphacalcidol is promising agent for preventing bone loss. Findings that GTP supplementation plus alphacalcidol administration increased bone mass via a decrease of oxidative stress and inflammation suggest a significant role of GTP plus alphacalcidol in bone health of patients with chronic inflammation. Introduction Studies have suggested that green tea polyphenols (GTP) or alphacalcidol are promising dietary supplements for preventing bone loss in women. However, the mechanism(s) related to the possible osteo-protective role of GTP plus D3 in chronic inflammation-induced bone loss is not well understood. Methods This study evaluated bioavailability, efficacy, and related mechanisms of GTP in combination with alphacalcidol in conserving bone loss in rats with chronic inflammation. A 12-week study of 2 (no GTP vs. 0.5% GTP in drinking water) × 2 (no alphacalcidol vs. 0.05 μg/kg alphacalcidol, 5×/week) factorial design in lipopolysaccharide-administered female rats was performed. In addition, a group receiving placebo administration was used to compare with a group receiving lipopolysaccharide administration only to evaluate the effect of lipopolysaccharide. Results Lipopolysaccharide administration resulted in lower values for bone mass, but higher values for serum tartrate-resistant acid phosphatase (TRAP), urinary 8-hydroxy-2′-deoxyguanosine, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. GTP supplementation increased urinary epigallocatechin and epicatechin concentrations. Both GTP supplementation and alphacalcidol administration resulted in a significant increase in bone mass, but a significant decrease in serum TRAP levels, urinary 8-hydroxydeoxyguanosine levels, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. A synergistic effect of GTP and alphacalcidol was observed in these parameters. Neither GTP nor alphacalcidol affected femoral bone area or serum osteocalcin. Conclusion We conclude that a bone-protective role of GTP plus alphacalcidol during chronic inflammation bone loss may be due to a reduction of oxidative stress damage and inflammation. PMID:20069278

The protective effect of Rhizoma Dioscoreae extract against alveolar bone loss in ovariectomized rats via regulating Wnt and p38 MAPK signaling.

PubMed

Zhang, Zhiguo; Xiang, Lihua; Bai, Dong; Wang, Wenlai; Li, Yan; Pan, Jinghua; Liu, Hong; Wang, Shaojun; Xiao, Gary Guishan; Ju, Dahong

2014-12-12

The aim of this study was to evaluate the osteoprotective effect of aqueous Rhizoma Dioscoreae extract (RDE) on the alveolar bone of rats with ovariectomy-induced bone loss. Female Wistar rats were subjected to either ovariectomy or a sham operation (SHAM). The ovariectomized (OVX) rats were treated with vehicle (OVX) or RDE by oral gavage or with 17β-estradiol (E2) subcutaneously. After treatments, the bone mineral density (BMD), the three-dimensional bone architecture of the alveolar bone and the plasma biomarkers of bone turnover were analyzed to assess bone metabolism, and the histomorphometry of the alveolar bone was observed. Microarrays were used to evaluate gene expression profiles in alveolar bone from RDE-treated and OVX rats. The differential expression of genes was further analyzed using Ingenuity Pathway Analysis (IPA). The key findings were verified using real-time quantitative RT-PCR (qRT-PCR). Our results showed that RDE inhibited alveolar bone loss in OVX rats. Compared to the OVX rats, the RDE-treated rats showed upregulated expression levels of 207 genes and downregulated expression levels of 176 genes in the alveolar bone. The IPA showed that several genes had the potential to code for proteins that were involved in the Wnt/β-catenin signaling pathway (Wnt7a, Fzd2, Tcf3, Spp1, Frzb, Sfrp2 and Sfrp4) and the p38 MAPK signaling pathway (Il1rn and Mapk14). These experiments revealed that RDE could inhibit ovariectomy-induced alveolar bone loss in rats. The mechanism of this anti-osteopenic effect in alveolar bone may be involved in the reduced abnormal bone remodeling, which is associated with the modulation of the Wnt/β-catenin and the p38 MAPK signaling pathways via gene regulation.

Pharmacological activation of aldehyde dehydrogenase 2 promotes osteoblast differentiation via bone morphogenetic protein-2 and induces bone anabolic effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mittal, Monika; Pal, Subhashis; China, Shyamsundar

Aldehyde dehydrogenases (ALDHs) are a family of enzymes involved in detoxifying aldehydes. Previously, we reported that an ALDH inhibitor, disulfiram caused bone loss in rats and among ALDHs, osteoblast expressed only ALDH2. Loss-of-function mutation in ALDH2 gene is reported to cause bone loss in humans which suggested its importance in skeletal homeostasis. We thus studied whether activating ALDH2 by N-(1, 3-benzodioxol-5-ylmethyl)-2, 6-dichlorobenzamide (alda-1) had osteogenic effect. We found that alda-1 increased and acetaldehyde decreased the differentiation of rat primary osteoblasts and expressions of ALDH2 and bone morphogenetic protein-2 (BMP-2). Silencing ALDH2 in osteoblasts abolished the alda-1 effects. Further, alda-1 attenuatedmore » the acetaldehyde-induced lipid-peroxidation and oxidative stress. BMP-2 is essential for bone regeneration and alda-1 increased its expression in osteoblasts. We then showed that alda-1 (40 mg/kg dose) augmented bone regeneration at the fracture site with concomitant increase in BMP-2 protein compared with control. The osteogenic dose (40 mg/kg) of alda-1 attained a bone marrow concentration that was stimulatory for osteoblast differentiation, suggesting that the tissue concentration of alda-1 matched its pharmacologic effect. In addition, alda-1 promoted modeling-directed bone growth and peak bone mass achievement, and increased bone mass in adult rats which reiterated its osteogenic effect. In osteopenic ovariectomized (OVX) rats, alda-1 reversed trabecular osteopenia with attendant increase in serum osteogenic marker (procollagen type I N-terminal peptide) and decrease in oxidative stress. Alda-1 has no effect on liver and kidney function. We conclude that activating ALDH2 by alda-1 had an osteoanabolic effect involving increased osteoblastic BMP-2 production and decreased OVX-induced oxidative stress. - Highlights: • Alda-1 induced osteoblast differentiation that involved upregulation of ALDH2 and BMP-2 • Alda-1 attenuated acetaldehyde-induced inhibition of osteoblast differentiation • Alda-1 enhanced bone regeneration at the fracture site and peak bone mass achievement • Alda-1 reversed trabecular osteopenia in OVX rats via an osteoanabolic mechanism.« less

Evaluation of Treadmill Exercise in a Lower Body Negative Pressure Chamber as a Countermeasure for Weightlessness-Induced Bone Loss: a Bed Rest Study with Identical Twins

NASA Technical Reports Server (NTRS)

Smith, Scott M.; Davis-Street, Janis E.; Fesperman, J. Vernell; Calkins, D. S.; Bawa, Maneesh; Macias, Brandon R.; Meyer, R. Scott; Hargens, Alan R.

2003-01-01

Counteracting bone loss is required for future space exploration. We evaluated the ability of treadmill exercise in a LBNP chamber to counteract bone loss in a 30-day bed rest study. Eight pairs of identical twins were randomly assigned to sedentary control or exercise groups. Exercise within LBNP decreased the bone resorption caused by bed rest and may provide a countermeasure for spaceflight. INTRODUCTION: Bone loss is one of the greatest physiological challenges for extended-duration space missions. The ability of exercise to counteract weightlessness-induced bone loss has been studied extensively, but to date, it has proven ineffective. We evaluated the effectiveness of a combination of two countermeasures-treadmill exercise while inside a lower body negative pressure (LBNP) chamber-on bone loss during a 30-day bed rest study. MATERIALS AND METHODS: Eight pairs of identical twins were randomized into sedentary (SED) or exercise/LBNP (EX/LBNP) groups. Blood and urine samples were collected before, several times during, and after the 30-day bed rest period. These samples were analyzed for markers of bone and calcium metabolism. Repeated measures ANOVA was used to determine statistical significance. Because identical twins were used, both time and group were treated as repeated variables. RESULTS: Markers of bone resorption were increased during bed rest in samples from sedentary subjects, including the collagen cross-links and serum and urinary calcium concentrations. For N-telopeptide and deoxypyridinoline, there were significant (p < 0.05) interactions between group (SED versus EX/LBNP) and phase of the study (sample collection point). Pyridinium cross-links were increased above pre-bed rest levels in both groups, but the EX/LBNP group had a smaller increase than the SED group. Markers of bone formation were unchanged by bed rest in both groups. CONCLUSIONS: These data show that this weight-bearing exercise combined with LBNP ameliorates some of the negative effects of simulated weightlessness on bone metabolism. This protocol may pave the way to counteracting bone loss during spaceflight and may provide valuable information about normal and abnormal bone physiology here on Earth.

Torque Loss After Miniscrew Placement: An In-Vitro Study Followed by a Clinical Trial.

PubMed

Migliorati, Marco; Drago, Sara; Barberis, Fabrizio; Schiavetti, Irene; Dalessandri, Domenico; Benedicenti, Stefano; Biavati, Armando Silvestrini

2016-01-01

To evaluate torque loss a week after insertion, both in an in vivo and an in vitro experimental setup were designed. In the in vivo setup a total of 29 miniscrews were placed in 20 patients who underwent orthodontic treatment. Maximum insertion torque (MIT) was evaluated at insertion time (T1). A week later, insertion torque was measured again by applying a quarter turn (T2); no load was applied on the screw during the first week. In the in vitro setup a total of 20 miniscrews were placed in pig rib bone samples. MIT was evaluated at insertion time (T1). Bone samples were kept in saline solution and controlled environment for a week during which the solution was refreshed every day. Afterwards, torque was measured again by applying a quarter turn (T2). The comparison of MIT over time was done calculating the percentage difference of the torque values between pre- and post-treatment and using the parametric two independent samples t-test or the non-parametric Mann-Whitney test. After a week unloaded miniscrews showed a mean loss of rotational torque of 36.3% and 40.9% in in vitro and in in vivo conditions, respectively. No statistical differences were found between the two different setups. Torque loss was observed after the first week in both study models; in vitro experimental setup provided a reliable study model for studying torque variation during the first week after insertion.

Torque Loss After Miniscrew Placement: An In-Vitro Study Followed by a Clinical Trial

PubMed Central

Migliorati, Marco; Drago, Sara; Barberis, Fabrizio; Schiavetti, Irene; Dalessandri, Domenico; Benedicenti, Stefano; Biavati, Armando Silvestrini

2016-01-01

To evaluate torque loss a week after insertion, both in an in vivo and an in vitro experimental setup were designed. In the in vivo setup a total of 29 miniscrews were placed in 20 patients who underwent orthodontic treatment. Maximum insertion torque (MIT) was evaluated at insertion time (T1). A week later, insertion torque was measured again by applying a quarter turn (T2); no load was applied on the screw during the first week. In the in vitro setup a total of 20 miniscrews were placed in pig rib bone samples. MIT was evaluated at insertion time (T1). Bone samples were kept in saline solution and controlled environment for a week during which the solution was refreshed every day. Afterwards, torque was measured again by applying a quarter turn (T2). The comparison of MIT over time was done calculating the percentage difference of the torque values between pre- and post-treatment and using the parametric two independent samples t-test or the non-parametric Mann–Whitney test. After a week unloaded miniscrews showed a mean loss of rotational torque of 36.3% and 40.9% in in vitro and in in vivo conditions, respectively. No statistical differences were found between the two different setups. Torque loss was observed after the first week in both study models; in vitro experimental setup provided a reliable study model for studying torque variation during the first week after insertion. PMID:27386011

Secreted Wnt Signaling Inhibitors in Disuse-Induced Bone Loss

DTIC Science & Technology

2011-05-01

decreased mechanical loading environment (e.g., as occurs in soldiers after spinal cord  injury ) leads to rapid bone loss via enhanced local...induced paralysis of the quadriceps,  hamstrings , and soleus) in one hindlimb of a series of mice  with mutations in Wnt modulators (Sost‐/‐, Dkk1...treatment strategies for overcoming the disuse‐associated bone loss that accompanies spinal cord  injury , and other battlefield‐related  injuries

Glucocorticoids Induce Bone and Muscle Atrophy by Tissue-Specific Mechanisms Upstream of E3 Ubiquitin Ligases

PubMed Central

Sato, Amy Y.; Richardson, Danielle; Cregor, Meloney; Davis, Hannah M.; Au, Ernie D.; McAndrews, Kevin; Zimmers, Teresa A.; Organ, Jason M.; Peacock, Munro; Plotkin, Lilian I.

2017-01-01

Glucocorticoid excess, either endogenous with diseases of the adrenal gland, stress, or aging or when administered for immunosuppression, induces bone and muscle loss, leading to osteopenia and sarcopenia. Muscle weakness increases the propensity for falling, which, combined with the lower bone mass, increases the fracture risk. The mechanisms underlying glucocorticoid-induced bone and muscle atrophy are not completely understood. We have demonstrated that the loss of bone and muscle mass, decreased bone formation, and reduced muscle strength, hallmarks of glucocorticoid excess, are accompanied by upregulation in both tissues in vivo of the atrophy-related genes atrogin1, MuRF1, and MUSA1. These are E3 ubiquitin ligases traditionally considered muscle-specific. Glucocorticoids also upregulated atrophy genes in cultured osteoblastic/osteocytic cells, in ex vivo bone organ cultures, and in muscle organ cultures and C2C12 myoblasts/myotubes. Furthermore, glucocorticoids markedly increased the expression of components of the Notch signaling pathway in muscle in vivo, ex vivo, and in vitro. In contrast, glucocorticoids did not increase Notch signaling in bone or bone cells. Moreover, the increased expression of atrophy-related genes in muscle, but not in bone, and the decreased myotube diameter induced by glucocorticoids were prevented by inhibiting Notch signaling. Thus, glucocorticoids activate different mechanisms in bone and muscle that upregulate atrophy-related genes. However, the role of these genes in the effects of glucocorticoids in bone is unknown. Nevertheless, these findings advance our knowledge of the mechanism of action of glucocorticoids in the musculoskeletal system and provide the basis for novel therapies to prevent glucocorticoid-induced atrophy of bone and muscle. PMID:28359087

Decreased bone mineral density in experimental myasthenia gravis in C57BL/6 mice.

PubMed

Oshima, Minako; Iida-Klein, Akiko; Maruta, Takahiro; Deitiker, Philip R; Atassi, M Zouhair

2017-09-01

Experimental autoimmune myasthenia gravis (EAMG), an animal model of myasthenia gravis (MG), can be induced in C57BL/6 (B6, H-2  b ) mice by 2-3 injections with Torpedo californica AChR (tAChR) in complete Freund's adjuvant. Some EAMG mice exhibit weight loss with muscle weakness. The loss in body weight, which is closely associated with bone structure, is particularly evident in EAMG mice with severe muscle weakness. However, the relationship between muscle weakness and bone loss in EAMG has not been studied before. Recent investigations on bone have shed light on association of bone health and immunological states. It is possible that muscle weakness in EAMG developed by anti-tAChR immune responses might accompany bone loss. We determined whether reduced muscle strength associates with decreased bone mineral density (BMD) in EAMG mice. EAMG was induced by two injections at 4-week interval of tAChR and adjuvants in two different age groups. The first tAChR injection was either at age 8 weeks or at 15 weeks. We measured BMD at three skeletal sites, including femur, tibia, and lumbar vertebrae, using dual energy X-ray absorptiometry. Among these bone areas, femur of EAMG mice in both age groups showed a significant decrease in BMD compared to control adjuvant-injected and to non-immunized mice. Reduction in BMD in induced EAMG at a later-age appears to parallel the severity of the disease. The results indicate that anti-tAChR autoimmune response alone can reduce bone density in EAMG mice. BMD reduction was also observed in adjuvant-injected mice in comparison to normal un-injected mice, suggesting that BMD decrease can occur even when muscle activity is normal. Decreased BMD observed in both tAChR-injected and adjuvant-injected mice groups were discussed in relation to innate immunity and bone-related immunology involving activated T cells and tumour necrosis factor-related cytokines that trigger osteoclastogenesis and bone loss.

MIF induces osteoclast differentiation and contributes to progression of periodontal disease in mice.

PubMed

Madeira, Mila Fernandes Moreira; Queiroz-Junior, Celso Martins; Costa, Graciela Mitre; Santos, Patrícia Campi; Silveira, Elcia Maria; Garlet, Gustavo Pompermaier; Cisalpino, Patrícia Silva; Teixeira, Mauro Martins; Silva, Tarcília Aparecida; Souza, Daniele da Glória

2012-02-01

Periodontal disease (PD) is a chronic inflammatory and alveolar bone destructive disease triggered by microorganisms from the oral biofilm. Oral inoculation of mice with the periodontopathogen Aggregatibacter actinomycetemcomitans (Aa) induces marked alveolar bone loss and local production of inflammatory mediators, including Macrophage Migration Inhibitory Factor (MIF). The role of MIF for alveolar bone resorption during PD is not known. In the present study, experimental PD was induced in BALB/c wild-type mice (WT) and MIF knockout mice (MIF⁻/⁻) through oral inoculation of Aa. Despite enhanced number of bacteria, MIF⁻/⁻ mice had reduced infiltration of TRAP-positive cells and reduced alveolar bone loss. This was associated with decreased neutrophil accumulation and increased levels of IL-10 in periodontal tissues. TNF-α production was similar in both groups. In vitro, LPS from Aa enhanced osteoclastic activity in a MIF-dependent manner. In conclusion, MIF has role in controlling bacterial growth in the context of PD but contributes more significantly to the progression of bone loss during PD by directly affecting differentiation and activity of osteoclasts. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Spaceflight-induced Bone Loss: Is there a Risk for Accelerated Osteoporosis after Return?

NASA Technical Reports Server (NTRS)

Sibonga, Jean

2008-01-01

The evidence-to to-date suggests that the rapid rate of site-specific bone loss in space, due to the unbalanced stimulation of bone resorption, may predispose crew members to irreversible changes in bone structure and microarchitecture. No analyses conducted in the postflight period to assess microarchitectural changes. There is no complete analysis of skeletal recovery in the postflight period to evaluate the structural changes that accompany increases in DXA aBMD. Postflight analyses based upon QCT scans performed on limited crew members indicate reductions in hip bone strength and incomplete recovery at 1 year. No recovery of trabecular vBMD after 1 year return (HRP IWG). Time course of bone loss in space unknown.

A crucial role for thiol antioxidants in estrogen-deficiency bone loss

PubMed Central

Lean, Jenny M.; Davies, Julie T.; Fuller, Karen; Jagger, Christopher J.; Kirstein, Barrie; Partington, Geoffrey A.; Urry, Zoë L.; Chambers, Timothy J.

2003-01-01

The mechanisms through which estrogen prevents bone loss are uncertain. Elsewhere, estrogen exerts beneficial actions by suppression of reactive oxygen species (ROS). ROS stimulate osteoclasts, the cells that resorb bone. Thus, estrogen might prevent bone loss by enhancing oxidant defenses in bone. We found that glutathione and thioredoxin, the major thiol antioxidants, and glutathione and thioredoxin reductases, the enzymes responsible for maintaining them in a reduced state, fell substantially in rodent bone marrow after ovariectomy and were rapidly normalized by exogenous 17-β estradiol. Moreover, administration of N-acetyl cysteine (NAC) or ascorbate, antioxidants that increase tissue glutathione levels, abolished ovariectomy-induced bone loss, while L-buthionine-(S,R)-sulphoximine (BSO), a specific inhibitor of glutathione synthesis, caused substantial bone loss. The 17-β estradiol increased glutathione and glutathione and thioredoxin reductases in osteoclast-like cells in vitro. Furthermore, in vitro NAC prevented osteoclast formation and NF-κB activation. BSO and hydrogen peroxide did the opposite. Expression of TNF-α, a target for NF-κB and a cytokine strongly implicated in estrogen-deficiency bone loss, was suppressed in osteoclasts by 17-β estradiol and NAC. These observations strongly suggest that estrogen deficiency causes bone loss by lowering thiol antioxidants in osteoclasts. This directly sensitizes osteoclasts to osteoclastogenic signals and entrains ROS-enhanced expression of cytokines that promote osteoclastic bone resorption. PMID:12975476

Associations among endocrine, inflammatory, and bone markers, body composition and weight loss induced bone loss.

PubMed

Labouesse, Marie A; Gertz, Erik R; Piccolo, Brian D; Souza, Elaine C; Schuster, Gertrud U; Witbracht, Megan G; Woodhouse, Leslie R; Adams, Sean H; Keim, Nancy L; Van Loan, Marta D

2014-07-01

Weight loss reduces co-morbidities of obesity, but decreases bone mass. Our aims were to (1) determine if adequate dairy intake attenuates weight loss-induced bone loss; (2) evaluate the associations of endocrine, inflammatory and bone markers, anthropometric and other parameters to bone mineral density and content (BMD, BMC) pre- and post-weight loss; and (3) model the contribution of these variables to post weight-loss BMD and BMC. Overweight/obese women (BMI: 28-37 kg/m2) were enrolled in an energy reduced (-500 kcal/d; -2092 kJ/d) diet with adequate dairy (AD: 3-4 servings/d; n=25, 32.2±8.8 years) or low dairy (LD: ≤1 serving/d; n=26, 31.7±8.4 years). BMD, BMC and body composition were measured by DXA. Bone markers (CTX, PYD, BAP, OC), endocrine (PTH, vitamin D, leptin, adiponectin, ghrelin, amylin, insulin, GLP-1, PAI-1, HOMA) and inflammatory markers (CRP, IL1-β, IL-6, IL-8, TNF-α, cortisol) were measured in serum or plasma. PA was assessed by accelerometry. Following weight loss, AD intake resulted in significantly greater (p=0.004) lumbar spine BMD and serum osteocalcin (p=0.004) concentration compared to LD. Pre- and post-body fat was negatively associated with hip and lumbar spine BMC (r=-0.28, p=0.04 to -0.45, p=0.001). Of note were the significant negative associations among bone markers and IL-1β, TNFα and CRP ranging from r = -0.29 (p=0.04) to r = -0.34 (p=0.01); magnitude of associations did not change with weight loss. Adiponectin was negatively related to change in osteocalcin. Factor analysis resulted in 8 pre- and post-weight loss factors. Pre-weight loss factors accounted for 13.7% of the total variance in pre-weight loss hip BMD; post-weight loss factors explained 19.6% of the total variance in post-weight loss hip BMD. None of the factors contributed to the variance in lumbar spine BMD. AD during weight loss resulted in higher lumbar spine BMD and osteocalcin compared to LD. Significant negative associations were observed between bone and inflammatory markers suggesting that inflammation suppresses bone metabolism. Using factor analysis, 19.6% of total variance in post-weight loss hip BMD could be explained by endocrine, immune, and anthropometric variables, but not lumbar spine BMD. Published by Elsevier Inc.

Associations among Endocrine, Inflammatory, and Bone Markers, Body Composition and Physical Activity to Weight Loss Induced Bone Loss

PubMed Central

Labouesse, Marie A.; Gertz, Erik R.; Piccolo, Brian D.; Souza, Elaine C.; Schuster, Gertrud U.; Witbracht, Megan G.; Woodhouse, Leslie R.; Adams, Sean H.; Keim, Nancy L.; Van Loan, Marta D.

2015-01-01

INTRODUCTION Weight loss reduces co-morbidities of obesity, but decreases bone mass. PURPOSE Our aims were to 1) determine if adequate dairy intake attenuates weight loss-induced bone loss; 2) evaluate the associations of endocrine, inflammatory and bone markers, anthropometric and other parameters to bone mineral density and content (BMD, BMC) pre- and post-weight loss; 3) model the contribution of these variables to post weight-loss BMD and BMC METHODS Overweight/obese women (BMI: 28–37 kg/m2) were enrolled in an energy reduced (−500 kcal/d; −2092 kJ/d) diet with adequate dairy (AD: 3–4 servings/d; n=25, 32.2 ± 8.8y) or low dairy (LD: ≤ 1 serving/d; n=26, 31.7 ± 8.4 y). BMD, BMC and body composition were measured by DXA. Bone markers (CTX, PYD, BAP, OC), endocrine (PTH, vitamin D, leptin, adiponectin, ghrelin, amylin, insulin, GLP-1, PAI-1, HOMA) and inflammatory markers (CRP, IL1-β, IL-6, IL-8, TNF-α, cortisol) were measured in serum or plasma. PA was assessed by accelerometry. RESULTS Following weight loss, AD intake resulted in significantly greater (p= 0.004) lumbar spine BMD and serum osteocalcin (p=0.004) concentration compared to LD. Pre- and post- body fat were negatively associated with hip and lumbar spine BMC (r= −0.28, p=0.04 to −0.45, p=0.001). Of note were the significant negative associations among bone markers and IL-1β, TNFα and CRP ranging from r = −0.29 (p=0.04) to r = −0.34 (p=0.01); magnitude of associations did not change with weight loss. Adiponectin was negatively related to change in osteocalcin. Factor analysis resulted in 8 pre- and post-weight loss Factors. Pre-weight loss Factors accounted for 13.7% of the total variance in pre-weight loss hip BMD; post-weight loss Factors explained 19.6% of the total variance in post-weight loss hip BMD. None of the Factors contributed to the variance in lumbar spine BMD. CONCLUSION AD during weight loss resulted in higher lumbar spine BMD and osteocalcin compared to LD. Significant negative associations were observed between bone and inflammatory markers suggesting inflammation suppresses bone metabolism. Using Factor Analysis, 19.6% of total variance in post-weight loss hip BMD could be explained by endocrine, immune, and anthropometric variables, but not lumbar spine BMD. PMID:24709689

Metabonomic profiling in studying anti-osteoporosis effects of strontium fructose 1,6-diphosphate on estrogen deficiency-induced osteoporosis in rats by GC/TOF-MS.

PubMed

Ma, Bo; Li, Xiaotian; Zhang, Qi; Wu, Di; Wang, Guangji; A, Jiye; Sun, Jianguo; Li, Jing; Liu, Yinhui; Wang, Yonglu; Ying, Hanjie

2013-10-15

A novel strontium salt compound strontium fructose 1, 6-diphosphate (FDP-Sr) has been proved to have highly effective for bone loss via dual effects of stimulating bone formation and suppressing bone absorption. In the present study, metabolomic approach was used to identify and study potential biomarkers associated with the effect and safety of FDP-Sr. The metabolomic profiles of bone loss induced by estrogen deficiency in a rat model was described to attain a system-level map of the shift on the metabolic response in plasma using GC/TOF-MS, after FDP-Sr was orally administered at the dose of 110 mg/kg/day for the prevention and 220 mg/kg/day for the treatment. Meanwhile, bone turnover biomarkers and bone mineral density were investigated to identify the specific changes of potential anti-osteoporosis effects of FDP-Sr. The differences in metabolic profiles between osteoporosis rats and FDP-Sr treated rats were well observed by the partial least squares-discriminant analysis (PLS-DA) to the MS spectra. Some metabolites including homocysteine, arachidonic acid, alanine, and hydroxyproline, which significantly changed during osteoporosis progression could be effectively reversed after FDP-Sr therapy. Of course some metabolites such as uric acid, glyceric acid, octadecadienoic acid, docosahexaenoic acid, oleic acid, and hexadecanoic acid were not found to reverse significantly after FDP-Sr administration. These results delineated the FDP-Sr effects-related metabolic alterations in the bone loss rats, suggesting that metabonomic analysis could provide helpful information on the new potential biomarkers relating to the mechanism of anti-osteoporosis action and side effects of FDP-Sr against estrogen deficiency induced bone loss. © 2013 Elsevier B.V. All rights reserved.

Long-Duration Spaceflight During the Bion-M1 Spaceflight Experiment Resulted in Significant Bone Loss in the Femoral Head and Alterations in Stem Cell Differentiation Potential in Male Mice

NASA Astrophysics Data System (ADS)

Blaber, Elizabeth; Almeida, Eduardo; Grigoryan, Eleonora; Globus, Ruth

Scientific understanding of the effects of microgravity on mammalian physiology has been limited to short duration spaceflight experiments (10-15 days). As long duration and inter-planetary missions are being initiated, there is a great need to understand the long-term effects of spaceflight on various physiological processes, including stem cell-based tissue regeneration. Bion-M1, for the first time, enabled the possibility of studying the effects of 30-days of microgravity exposure on a mouse model with sufficient sample size to enable statistical analysis. In this experiment, we hypothesized that microgravity negatively impacts stem cell based tissue regeneration, such as bone remodeling and regeneration from hematopoietic and mesenchymal precursors, thereby resulting in tissue degeneration in mice exposed to spaceflight. To test this hypothesis we collected the pelvis and proximal femur from space-flown mice and asynchronous ground controls and analyzed bone and bone marrow using techniques including Microcomputed Tomography (MicroCT), and in-vitro differentiation and differentiating cell motility assays. To determine the effects of 30-days spaceflight on bone tissue mass, we used MicroCT to analyze the trabecular bone of the femoral head and the cortical bone of the femoral neck and mid-shaft. We found that spaceflight caused a 45% decrease in bone volume ratio, a 17% decrease in trabecular thickness, a 25% decrease in trabecular number, and a 17% increase in trabecular spacing of trabecular bone. Furthermore, structural model index and trabecular pattern factor were increased by 32% and 82% respectively indicating that 30-days spaceflight resulted not only in a large loss of trabecular bone but also in a decrease of bone strength indicators. Analysis of the femoral neck cortical bone showed an increase in marrow area and cortical porosity indicating an overall widening of the femoral neck. Interestingly, no significant alterations were found in the cortical bone of the femoral mid-shaft. To determine the regenerative potential of osteoblasts derived from mesenchymal stem cells flown in microgravity we conducted post-flight in-vitro osteoblastogenesis and mineralized nodule formation assays. We found an increase in post-flight differentiation and mineralization of microgravity-flown osteogenic cells, suggesting an accumulation of precursor cells that fail to fully differentiate in space, and then resume vigorous osteogenesis upon reloading at 1g. Overall, these preliminary results indicate that exposure to 30-days spaceflight causes significant trabecular bone loss in the femoral head, a decrease in trabecular bone strength indicators, and compensatory widening of the femoral neck. These results, coupled with diminished regenerative potential of bone marrow stem cells during mechanical unloading in microgravity, have potentially serious implications for bone health and fracture risk during long-duration spaceflight.

Role of subchondral bone properties and changes in development of load-induced osteoarthritis in mice.

PubMed

Adebayo, O O; Ko, F C; Wan, P T; Goldring, S R; Goldring, M B; Wright, T M; van der Meulen, M C H

2017-12-01

Animal models recapitulating post-traumatic osteoarthritis (OA) suggest that subchondral bone (SCB) properties and remodeling may play major roles in disease initiation and progression. Thus, we investigated the role of SCB properties and its effects on load-induced OA progression by applying a tibial loading model on two distinct mouse strains treated with alendronate (ALN). Cyclic compression was applied to the left tibia of 26-week-old male C57Bl/6 (B6, low bone mass) and FVB (high bone mass) mice. Mice were treated with ALN (26 μg/kg/day) or vehicle (VEH) for loading durations of 1, 2, or 6 weeks. Changes in articular cartilage and subchondral and epiphyseal cancellous bone were analyzed using histology and microcomputed tomography. FVB mice exhibited thicker cartilage, a thicker SCB plate, and higher epiphyseal cancellous bone mass and tissue mineral density than B6 mice. Loading induced cartilage pathology, osteophyte formation, and SCB changes; however, lower initial SCB mass and stiffness in B6 mice did not attenuate load-induced OA severity compared to FVB mice. By contrast, FVB mice exhibited less cartilage damage, and slower-growing and less mature osteophytes. In B6 mice, inhibiting bone remodeling via ALN treatment exacerbated cartilage pathology after 6 weeks of loading, while in FVB mice, inhibiting bone remodeling protected limbs from load-induced cartilage loss. Intrinsically lower SCB properties were not associated with attenuated load-induced cartilage loss. However, inhibiting bone remodeling produced differential patterns of OA pathology in animals with low compared to high SCB properties, indicating that these factors do influence load-induced OA progression. Copyright © 2017 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

The effects and mechanisms of clinorotation on proliferation and differentiation in bone marrow mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Ming; Wang, Yongchun; Yang, Min

Data from human and rodent studies have demonstrated that microgravity induces observed bone loss in real spaceflight or simulated experiments. The decrease of bone formation and block of maturation may play important roles in bone loss induced by microgravity. The aim of this study was to investigate the changes of proliferation and differentiation in bone marrow mesenchymal stem cells (BMSCs) induced by simulated microgravity and the mechanisms underlying it. We report here that clinorotation, a simulated model of microgravity, decreased proliferation and differentiation in BMSCs after exposure to 48 h simulated microgravity. The inhibited proliferation are related with blocking the cellmore » cycle in G2/M and enhancing the apoptosis. While alterations of the osteoblast differentiation due to the decreased SATB2 expression induced by simulated microgravity in BMSCs. - Highlights: • Simulated microgravity inhibited proliferation and differentiation in BMSCs. • The decreased proliferation due to blocked cell cycle and enhanced the apoptosis. • The inhibited differentiation accounts for alteration of SATB2, Hoxa2 and Cbfa1.« less

Altered bone turnover during spaceflight

NASA Technical Reports Server (NTRS)

Turner, R. T.; Morey, E. R.; Liu, C.; Baylink, D. J.

1982-01-01

Modifications in calcium metabolism during spaceflight were studied, using parameters that reflect bone turnover. Bone formation rate, medullary area, bone length, bone density, pore size distribution, and differential bone cell number were evaluated in growing rate both immediately after and 25 days after orbital spaceflights aboard the Soviet biological satellites Cosmos 782 and 936. The primary effect of space flight on bone turnover was a reversible inhibition of bone formation at the periosteal surface. A simultaneous increase in the length of the periosteal arrest line suggests that bone formation ceased along corresponding portions of that surface. Possible reasons include increased secretion of glucocorticoids and mechanical unloading of the skeleton due to near-weightlessness, while starvation and immobilization are excluded as causes.

The botanical molecule p-hydroxycinnamic acid as a new osteogenic agent: insight into the treatment of cancer bone metastases.

PubMed

Yamaguchi, Masayoshi

2016-10-01

Bone homeostasis is maintained through a balance between osteoblastic bone formation and osteoclastic bone resorption. Bone loss with aging is induced by decreasing in osteoblastic bone formation and increasing in osteoclastic bone resorption, thereby leading to osteoporosis. Osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public heath problem. Pharmacologic and nutritional factors may play a role in the prevention and treatment of bone loss with aging. p-Hydroxycinnamic acid (HCA), which stimulates bone mineralization in mouse bone tissues in vitro, has been found to be present in the leafstalk of wasabi (Wasabi japonica MATSUM) among various food and plants. Other phenolic acids including cinnamic acid, ferulic acid, caffeic acid and 3,4-dimethoxycinnamic acid did not have osteogenic effects. HCA was demonstrated to stimulate osteoblastic bone formation and suppresses osteoclastic bone resorption in vitro by antagonizing activation of the nuclear factor kappa B. Oral administration of HCA was found to exhibit restorative effects on bone loss induced by ovariectomy and diabetic states, supporting a role in the treatment of osteoporosis. Moreover, HCA was demonstrated to prevent the suppressed osteoblastic mineralization and the enhanced osteoclastogenesis in mouse bone marrow cells cocultured with bone metastatic MDA-MB-231 human breast cancer cells in vitro. The botanical molecule HCA, as a new osteogenic agent, is suggested to play a role in the treatment of cancer bone metastases. This review will discuss an advanced recent finding that HCA may be a useful agent to treat bone metabolic disorder.

Non-canonical Wnt4 prevents skeletal aging and inflammation by inhibiting NF-κB

PubMed Central

Yu, Bo; Chang, Jia; Liu, Yunsong; Li, Jiong; Kevork, Kareena; Al-Hezaimi, Khalid; Graves, Dana T; Park, No-Hee; Wang, Cun-Yu

2014-01-01

Aging-related bone loss and osteoporosis affect millions of patients worldwide. Chronic inflammation associated with aging and arthritis promotes bone resorption and impairs bone formation. Here we show that Wnt4 attenuated bone loss in osteoporosis and skeletal aging by inhibiting nuclear factor-kappa B (NF-κB) via non-canonical Wnt signaling. Transgenic mice expressing Wnt4 from osteoblasts were significantly protected from bone loss and chronic inflammation induced by ovariectomy, tumor necrosis factor or natural aging. In addition to promoting bone formation, Wnt4 could inhibit osteoclast formation and bone resorption. Mechanistically, Wnt4 inhibited transforming growth factor beta-activated kinase 1-mediated NF-κB activation in macrophages and osteoclast precursors independent of β-catenin. Moreover, recombinant Wnt4 proteins were able to alleviate osteoporotic bone loss and inflammation by inhibiting NF-κB in vivo. Taken together, our results suggest that Wnt4 might be used as a therapeutic agent for treating osteoporosis by attenuating NF-κB. PMID:25108526

Streptozocin-induced type-1 diabetes mellitus results in decreased density of CGRP sensory and TH sympathetic nerve fibers that are positively correlated with bone loss at the mouse femoral neck.

PubMed

Enríquez-Pérez, Iris A; Galindo-Ordoñez, Karla E; Pantoja-Ortíz, Christian E; Martínez-Martínez, Arisaí; Acosta-González, Rosa I; Muñoz-Islas, Enriqueta; Jiménez-Andrade, Juan M

2017-08-10

Type-1 diabetes mellitus (T1DM) results in loss of innervation in some tissues including epidermis and retina; however, the effect on bone innervation is unknown. Likewise, T1DM results in pathological bone loss and increased risk of fracture. Thus, we quantified the density of calcitonin gene-related peptide (CGRP + ) sensory and tyrosine hydroxylase (TH + ) sympathetic nerve fibers and determined the association between the innervation density and microarchitecture of trabecular bone at the mouse femoral neck. Ten weeks-old female mice received 5 daily administrations of streptozocin (i.p. 50mg/kg) or citrate (control group). Twenty weeks later, femurs were analyzed by microCT and processed for immunohistochemistry. Confocal microscopy analysis revealed that mice with T1DM had a significant loss of both CGRP + and TH + nerve fibers in the bone marrow at the femoral neck. Likewise, microCT analysis revealed a significant decrease in the trabecular bone mineral density (tBMD), bone volume/total volume ratio (BV/TB), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp) in mice with T1DM as compared to control mice. Analysis of correlation revealed a positive and significant association between density of CGRP + or TH + nerve fibers with tBMD, BV/TV, Tb.Th and Tb.Sp, but not with trabecular number (there was a positive association only for CGRP + ) and degree of anisotropy (DA). This study suggests an interaction between sensory and sympathetic nervous system and T1DM-induced bone loss. Identification of the factors involved in the loss of CGRP + sensory and TH + sympathetic fibers and how they regulate bone loss may result in new avenues to treat T1DM-related osteoporosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Actions of Tamoxifen and Estrogen on Osteoblast Protein Kinase C Expression.

DTIC Science & Technology

1996-07-01

extended period of time over which estrogen deficiency -induced bone loss occurs. Postmenopausal bone loss occurs gradually over several years, and changes...Identification of luteal estrogen-modulated lipid- stimulated kinase as protein kinase C5. J Biol Chem 267:17061-17068. 24. Cutler RE Jr, Maizels ET

Muscle-specific and age-related changes in protein synthesis and protein degradation in response to hindlimb unloading in rats

PubMed Central

Baehr, Leslie M.; West, Daniel W. D.; Marshall, Andrea G.; Marcotte, George R.; Baar, Keith

2017-01-01

Disuse is a potent inducer of muscle atrophy, but the molecular mechanisms driving this loss of muscle mass are highly debated. In particular, the extent to which disuse triggers decreases in protein synthesis or increases in protein degradation, and whether these changes are uniform across muscles or influenced by age, is unclear. We aimed to determine the impact of disuse on protein synthesis and protein degradation in lower limb muscles of varied function and fiber type in adult and old rats. Alterations in protein synthesis and degradation were measured in the soleus, medial gastrocnemius, and tibialis anterior (TA) muscles of adult and old rats subjected to hindlimb unloading (HU) for 3, 7, or 14 days. Loss of muscle mass was progressive during the unloading period, but highly variable (−9 to −38%) across muscle types and between ages. Protein synthesis decreased significantly in all muscles, except for the old TA. Atrophy-associated gene expression was only loosely associated with protein degradation as muscle RING finger-1, muscle atrophy F-box (MAFbx), and Forkhead box O1 expression significantly increased in all muscles, but an increase in proteasome activity was only observed in the adult soleus. MAFbx protein levels were significantly higher in the old muscles compared with adult muscles, despite the old having higher expression of microRNA-23a. These results indicate that adult and old muscles respond similarly to HU, and the greatest loss in muscle mass occurs in predominantly slow-twitch extensor muscles due to a concomitant decrease in protein synthesis and increase in protein degradation. NEW & NOTEWORTHY In this study, we showed that age did not intensify the atrophy response to unloading in rats, but rather that the degree of atrophy was highly variable across muscles, indicating that changes in protein synthesis and protein degradation occur in a muscle-specific manner. Our data emphasize the importance of studying muscles of varying fiber-type and physiological function at multiple time points to fully understand the molecular mechanisms responsible for disuse atrophy. PMID:28336537

Prevention of bone loss in ovariectomized rats: the effect of Salvia miltiorrhiza extracts.

PubMed

Chae, H J; Chae, S W; Yun, D H; Keum, K S; Yoo, S K; Kim, H R

2004-02-01

The preventive effect of Salvia miltiorrhiza extracts (SMEs) on the progress of bone loss induced by ovariectomy (OVX) was studied in rats. We measured body weight and bone histomorphometry in sham, OVX or SMEs-administered OVX rats. From light microscopic analyses, a porous or erosive appearances were observed on the surface of trabecular bone of tibia in OVX rats, whereas those of the same bone in sham rats and in SMEs-administered rats were composed of fine particles. The trabecular bone area and trabecular thickness in OVX rats decreased by 50% from those in sham rats, these decreases were completely inhibited by administration of SMEs for 7 weeks. In this study, the mechanical strength in femur neck was significantly enhanced by the treatment of SMEs for 7 weeks. In OVX rats, free T3 was normal in all cases, whereas free T4 was significantly increased. Although there was no difference between OVX and SMEs-administered rats in T3 level, we have found significant difference between them in T4 level. These results strongly suggest that SMEs are effective in preventing the development of bone loss induced by OVX in rats.

IL-17A GENE TRANSFER INDUCES BONE LOSS AND EPIDERMAL HYPERPLASIA ASSOCIATED WITH PSORIATIC ARTHRITIS

PubMed Central

ADAMOPOULOS, IANNIS E.; SUZUKI, ERIKA; CHAO, CHENG-CHI; GORMAN, DAN; ADDA, SARVESH; MAVERAKIS, EMANUAL; ZARBALIS, KONSTANTINOS; GEISSLER, RICHARD; ASIO, AGELIO; BLUMENSCHEIN, WENDY M; McCLANAHAN, TERRILL; DE WAAL MALEFYT, RENE; GERSHWIN, M. ERIC; BOWMAN, EDWARD P.

2014-01-01

Background Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by clinical features that include bone loss and epidermal hyperplasia. Aberrant cytokine expression has been linked to joint and skin pathology; however, it is unclear which cytokines are critical for disease initiation. IL-17A participates in many pathologic immune responses; however, its role in PsA has not been fully elucidated. Objective To determine the role of IL-17A in epidermal hyperplasia and bone destruction associated with psoriatic arthritis. Design An in vivo gene transfer approach was used to investigate the role of IL-17A in animal models of inflammatory (Collagen-induced arthritis) and non-inflammatory (RANKL-gene transfer) bone loss. Results IL-17A gene transfer induced the expansion of IL-17RA+CD11b+Gr1low osteoclast precursors and a concomitant elevation of biomarkers indicative of bone resorption. This occurred at a time preceding noticeable joint inflammation suggesting that IL-17A is critical for the induction of pathological bone resorption through direct activation of osteoclast precursors. Moreover, IL-17A induced a second myeloid population CD11b+Gr1high neutrophil-like cells which was associated with cutaneous pathology including epidermal hyperplasia, parakeratosis, and Munro’s microabscesses formation. Conclusion Collectively, these data support that IL-17A can play a key role in the pathogenesis of inflammation-associated arthritis and/or skin disease, as observed in PsA. PMID:24567524

Forces associated with launch into space do not impact bone fracture healing

NASA Astrophysics Data System (ADS)

Childress, Paul; Brinker, Alexander; Gong, Cynthia-May S.; Harris, Jonathan; Olivos, David J.; Rytlewski, Jeffrey D.; Scofield, David C.; Choi, Sungshin Y.; Shirazi-Fard, Yasaman; McKinley, Todd O.; Chu, Tien-Min G.; Conley, Carolynn L.; Chakraborty, Nabarun; Hammamieh, Rasha; Kacena, Melissa A.

2018-02-01

Segmental bone defects (SBDs) secondary to trauma invariably result in a prolonged recovery with an extended period of limited weight bearing on the affected limb. Soldiers sustaining blast injuries and civilians sustaining high energy trauma typify such a clinical scenario. These patients frequently sustain composite injuries with SBDs in concert with extensive soft tissue damage. For soft tissue injury resolution and skeletal reconstruction a patient may experience limited weight bearing for upwards of 6 months. Many small animal investigations have evaluated interventions for SBDs. While providing foundational information regarding the treatment of bone defects, these models do not simulate limited weight bearing conditions after injury. For example, mice ambulate immediately following anesthetic recovery, and in most cases are normally ambulating within 1-3 days post-surgery. Thus, investigations that combine disuse with bone healing may better test novel bone healing strategies. To remove weight bearing, we have designed a SBD rodent healing study in microgravity (μG) on the International Space Station (ISS) for the Rodent Research-4 (RR-4) Mission, which launched February 19, 2017 on SpaceX CRS-10 (Commercial Resupply Services). In preparation for this mission, we conducted an end-to-end mission simulation consisting of surgical infliction of SBD followed by launch simulation and hindlimb unloading (HLU) studies. In brief, a 2 mm defect was created in the femur of 10 week-old C57BL6/J male mice (n = 9-10/group). Three days after surgery, 6 groups of mice were treated as follows: 1) Vivarium Control (maintained continuously in standard cages); 2) Launch Negative Control (placed in the same spaceflight-like hardware as the Launch Positive Control group but were not subjected to launch simulation conditions); 3) Launch Positive Control (placed in spaceflight-like hardware and also subjected to vibration followed by centrifugation); 4) Launch Positive Experimental (identical to Launch Positive Control group, but placed in qualified spaceflight hardware); 5) Hindlimb Unloaded (HLU, were subjected to HLU immediately after launch simulation tests to simulate unloading in spaceflight); and 6) HLU Control (single housed in identical HLU cages but not suspended). Mice were euthanized 28 days after launch simulation and bone healing was examined via micro-Computed Tomography (μCT). These studies demonstrated that the mice post-surgery can tolerate launch conditions. Additionally, forces and vibrations associated with launch did not impact bone healing (p = .3). However, HLU resulted in a 52.5% reduction in total callus volume compared to HLU Controls (p = .0003). Taken together, these findings suggest that mice having a femoral SBD surgery tolerated the vibration and hypergravity associated with launch, and that launch simulation itself did not impact bone healing, but that the prolonged lack of weight bearing associated with HLU did impair bone healing. Based on these findings, we proceeded with testing the efficacy of FDA approved and novel SBD therapies using the unique spaceflight environment as a novel unloading model on SpaceX CRS-10.

Desalted Duck Egg White Peptides Promote Calcium Uptake and Modulate Bone Formation in the Retinoic Acid-Induced Bone Loss Rat and Caco-2 Cell Model.

PubMed

Hou, Tao; Liu, Yanshuang; Kolba, Nikolai; Guo, Danjun; He, Hui

2017-05-12

Desalted duck egg white peptides (DPs) have been proven to promote calcium uptake in Caco-2 cells and rats treated with a calcium-deficient diet. The retinoic acid-induced bone loss model was used to evaluate the effect of DPs on calcium absorption and bone formation. Three-month-old Wistar female rats were treated with 0.9% saline, DPs (800 mg/kg), or alendronate (5 mg/kg) for three weeks immediately after retinoic acid treatment (80 mg/kg) once daily for two weeks. The model group was significantly higher in serum bone alkaline phosphatase than the other three groups ( p < 0.05), but lower in calcium absorption rate, serum osteocalcin, bone weight index, bone calcium content, bone mineral density, and bone max load. After treatment with DPs or alendronate, the absorption rate increased and some serum and bone indices recovered. The morphology results indicated bone tissue form were ameliorated and numbers of osteoclasts decreased after supplementation with DPs or alendronate. The in vitro study showed that the transient receptor potential vanilloid 6 (TRPV6) calcium channel was the main transport pathway of both DPs and Val-Ser-Glu-Glu peptitde (VSEE), which was identified from DPs. Our results indicated that DPs could be a promising alternative to current therapeutic agents for bone loss because of the promotion of calcium uptake and regulation of bone formation.

Evaluation in a Dog Model of Three Antimicrobial Glassy Coatings: Prevention of Bone Loss around Implants and Microbial Assessments

PubMed Central

López-Píriz, Roberto; Solá-Linares, Eva; Rodriguez-Portugal, Mercedes; Malpica, Beatriz; Díaz-Güemes, Idoia; Enciso, Silvia; Esteban-Tejeda, Leticia; Cabal, Belén; Granizo, Juan José; Moya, José Serafín; Torrecillas, Ramón

2015-01-01

Objectives The aim of the present study is to evaluate, in a ligature-induced peri-implantitis model, the efficacy of three antimicrobial glassy coatings in the prevention of biofilm formation, intrasulcular bacterial growth and the resulting peri-implant bone loss. Methods Mandibular premolars were bilaterally extracted from five beagle dogs. Four dental implants were inserted on each hemiarch. Eight weeks after, one control zirconia abutment and three with different bactericidal coatings (G1n-Ag, ZnO35, G3) were connected. After a plaque control period, bacterial accumulation was allowed and biofilm formation on abutments was observed by Scanning Electron Microscopy (SEM). Peri-implantitis was induced by cotton ligatures. Microbial samples and peri-implant crestal bone levels of all implant sites were obtained before, during and after the breakdown period. Results During experimental induce peri-implantitis: colony forming units counts from intrasulcular microbial samples at implants with G1n-Ag coated abutment remained close to the basal inoculum; G3 and ZnO35 coatings showed similar low counts; and anaerobic bacterias counts at control abutments exhibited a logarithmic increase by more than 2. Bone loss during passive breakdown period was no statistically significant. Additional bone loss occurred during ligature-induce breakdown: 0.71 (SD 0.48) at G3 coating, 0.57 (SD 0.36) at ZnO35 coating, 0.74 (SD 0.47) at G1n-Ag coating, and 1.29 (SD 0.45) at control abutments; and statistically significant differences (p<0.001) were found. The lowest bone loss at the end of the experiment was exhibited by implants dressing G3 coated abutments (mean 2.1; SD 0.42). Significance Antimicrobial glassy coatings could be a useful tool to ward off, diminish or delay peri-implantitis progression. PMID:26489088

Safflower bud inhibits RANKL-induced osteoclast differentiation and prevents bone loss in ovariectomized mice.

PubMed

Choi, Joo-Hee; Lim, Seul-Ki; Kim, Dong-Il; Park, Min-Jung; Kim, Young-Kuk; Lee, An-Chul; Kim, Young-Min; Yang, Soo-Jin; Park, Jong-Hwan

2017-10-15

The powder and extract of safflower seeds are known to be effective in the prevention of bone loss in ovariectomized animals. However, the inhibitory effect and molecular mechanisms of safflower bud (SB), the germinated safflower, on bone destruction is unclear. The present study was designed to investigate the inhibitory effect and molecular mechanism of SB on osteoclastic differentiation and on bone loss in ovarietomized (OVX) mice. Osteoclastogenesis was determined by TRAP staining, F-actin ring formation, and bone resorption assay. NF-κB and MAPKs activation was analyzed by transfection assay and Western blot, respectively. Real-time PCR was performed to examine the expression of osteoclastogenesis-related genes. Histological changes, increases in TRAP-positive cells, and cathepsin K expression were examined in the metaphysis of OVX mice. Density of bone marrow was evaluated by µCT. SB inhibited the RANKL-induced differentiation of BMDMs into osteoclasts in a dose-dependent manner. F-actin ring formation and bone resorption were also reduced by SB in RANKL-treated BMDMs. In addition, SB decreased the activation of NF-κB and MAPKs and the expression of osteoclastogenesis-related genes in BMDMs treated with RANKL. Feeding of SB-included diet prevented bone loss in OVX mice. The number of TRAP-positive cells and level of protein expression of cathepsin K was reduced and bone mineral density was increased in the metaphysis of mice fed SB compared with OVX mice. These findings suggest that SB can be a preventive and therapeutic candidate for destructive bone diseases. Copyright © 2017. Published by Elsevier GmbH.

Water extract of the fruits of Alpinia oxyphylla inhibits osteoclast differentiation and bone loss.

PubMed

Ha, Hyunil; Shim, Ki-Shuk; Kim, Taesoo; Lee, Chung-Jo; Park, Ji Hyung; Kim, Han Sung; Ma, Jin Yeul

2014-09-23

Excessive bone resorption by osteoclasts causes pathological bone destruction, seen in various bone diseases. There is accumulating evidence that certain herbal extracts have beneficial effects on bone metabolism. The fruits of Alpinia oxyphylla has been traditionally used for the treatment of diarrhea and enuresis. In this study, we investigated the effects of water extract of the fruits of Alpinia oxyphylla (WEAO) on osteoclast differentiation and osteoclast-mediated bone destruction. For osteoclast differentiation assay, mouse bone marrow-derived macrophages (BMMs) were cultured in the presence of RANKL and M-CSF. RANKL signaling pathways and gene expression of transcription factors regulating osteoclast differentiation were investigated by real-time PCR and Western blotting. A constitutively active form of NFATc1 was retrovirally transduced into BMMs. Bone resorbing activity of mature osteoclast was examined on a plate coated with an inorganic crystalline calcium phosphate. The in vivo effect against bone destruction was assessed in a murine model of RANKL-induced osteoporosis by micro-computed tomography and bone metabolism marker analyses. WEAO dose-dependently inhibited RANKL-induced osteoclast differentiation from BMMs by targeting the early stages of osteoclast differentiation. WEAO inhibited RANKL-induced expression of NFATc1, the master regulator of osteoclast differentiation. Overexpression of a constitutively active form of NFATc1 blunted the inhibitory effect of WEAO on osteoclast differentiation, suggesting that NFATc1 is a critical target of the inhibitory action of WEAO. WEAO inhibited RANKL-induced expression of c-Fos, an upstream activator of NFATc1, by suppressing the classical NF-κB signaling pathway. WEAO also inhibited RANKL-induced down-regulation of Id2 and MafB, negative regulators of NFATc1. WEAO does not directly affect bone resorbing activity of mature osteoclasts. In accordance with the in vitro results, WEAO attenuated RANKL-induced bone destruction in mice by inhibiting osteoclast differentiation. This study demonstrates that WEAO exhibits a protective effect against bone loss by inhibiting RANKL-induced osteoclast differentiation. These findings suggest that WEAO might be useful for the prevention and treatment of bone diseases associated with excessive bone resorption.

Colitis induced bone loss is gender dependent and associated with increased inflammation

PubMed Central

Irwin, Regina; Lee, Taehyung; Young, Vincent B.; Parameswaran, Narayanan; McCabe, Laura R.

2014-01-01

Background Patients with inflammatory bowel disease (IBD) are at increase risk for bone loss and fractures. Therefore, in the present study, we examined the effect of experimental IBD on bone health. Methods We used a murine model of colitis, H. hepaticus-infected IL-10 deficient animals. Molecular and histological properties of bone and intestine were examined to identify the immunopathological consequences of colitis in male and female mice. Results At 6 weeks post-infection we observed significant trabecular bone loss in male but surprisingly not in female mice. This was true for both distal femur and vertebral locations. In addition, H. hepaticus infection suppressed osteoblast markers only in males. Consistent with effects on bone health, male mice with H. hepaticus infection had more severe colitis as determined by histology and elevated levels of inflammatory cytokines in the colon. While H. hepaticus levels in the stool appeared similar in male and female mice 1-week after infection, by 6-weeks H. hepaticus levels were greater in male mice, indicating that H. hepaticus survival and virulence within the GI tract could be gender-dependent. Conclusion In summary, H. hepaticus induced colitis severity and associated bone loss is gender regulated, possibly as a result of gender-specific effects on H. hepaticus colonization in the mouse GI tract and the consequent immunopathologic responses. PMID:23702805

Effects of Zoledronate and Mechanical Loading during Simulated Weightlessness on Bone Structure and Mechanical Properties

NASA Technical Reports Server (NTRS)

Scott, R. T.; Nalavadi, M. O.; Shirazi-Fard, Y.; Castillo, A. B.; Alwood, J. S.

2016-01-01

Space flight modulates bone remodeling to favor bone resorption. Current countermeasures include an anti-resorptive drug class, bisphosphonates (BP), and high-force loading regimens. Does the combination of anti-resorptives and high-force exercise during weightlessness have negative effects on the mechanical and structural properties of bone? In this study, we implemented an integrated model to mimic mechanical strain of exercise via cyclical loading (CL) in mice treated with the BP Zoledronate (ZOL) combined with hindlimb unloading (HU). Our working hypothesis is that CL combined with ZOL in the HU model induces additive structural and mechanical changes. Thirty-two C57BL6 mice (male,16 weeks old, n8group) were exposed to 3 weeks of either HU or normal ambulation (NA). Cohorts of mice received one subcutaneous injection of ZOL (45gkg), or saline vehicle, prior to experiment. The right tibia was axially loaded in vivo, 60xday to 9N in compression, repeated 3xweek during HU. During the application of compression, secant stiffness (SEC), a linear estimate of slope of the force displacement curve from rest (0.5N) to max load (9.0N), was calculated for each cycle once per week. Ex vivo CT was conducted on all subjects. For ex vivo mechanical properties, non-CL left femurs underwent 3-point bending. In the proximal tibial metaphysis, HU decreased, CL increased, and ZOL increased the cancellous bone volume to total volume ratio by -26, +21, and +33, respectively. Similar trends held for trabecular thickness and number. Ex vivo left femur mechanical properties revealed HU decreased stiffness (-37),and ZOL mitigated the HU stiffness losses (+78). Data on the ex vivo Ultimate Force followed similar trends. After 3 weeks, HU decreased in vivo SEC (-16). The combination of CL+HU appeared additive in bone structure and mechanical properties. However, when HU + CL + ZOL were combined, ZOL had no additional effect (p0.05) on in vivo SEC. Structural data followed this trend with ZOL not modulating trabecular thickness in CL + NAHU mice. In summary, our integrated model simulates the combination of weightlessness, exercise-induced mechanical strain, and anti-resorptive treatment that astronauts experience during space missions. Based on these results, we conclude that, at the structural and stiffness level, zoledronate treatment during simulated spaceflight does not impede the skeletal response to axial compression. In contrast to our hypothesis, our data show that zoledronate confers no additional mechanical or structural benefit beyond those gained from cyclical loading.

Chronic skin inflammation leads to bone loss by IL-17-mediated inhibition of Wnt signaling in osteoblasts.

PubMed

Uluçkan, Özge; Jimenez, Maria; Karbach, Susanne; Jeschke, Anke; Graña, Osvaldo; Keller, Johannes; Busse, Björn; Croxford, Andrew L; Finzel, Stephanie; Koenders, Marije; van den Berg, Wim; Schinke, Thorsten; Amling, Michael; Waisman, Ari; Schett, Georg; Wagner, Erwin F

2016-03-16

Inflammation has important roles in tissue regeneration, autoimmunity, and cancer. Different inflammatory stimuli can lead to bone loss by mechanisms that are not well understood. We show that skin inflammation induces bone loss in mice and humans. In psoriasis, one of the prototypic IL-17A-mediated inflammatory human skin diseases, low bone formation and bone loss correlated with increased serum IL-17A levels. Similarly, in two mouse models with chronic IL-17A-mediated skin inflammation,K14-IL17A(ind)andJunB(Δep), strong inhibition of bone formation was observed, different from classical inflammatory bone loss where osteoclast activation leads to bone degradation. We show that under inflammatory conditions, skin-resident cells such as keratinocytes, γδ T cells, and innate lymphoid cells were able to express IL-17A, which acted systemically to inhibit osteoblast and osteocyte function by a mechanism involving Wnt signaling. IL-17A led to decreased Wnt signaling in vitro, and importantly, pharmacological blockade of IL-17A rescued Wnt target gene expression and bone formation in vivo. These data provide a mechanism where IL-17A affects bone formation by regulating Wnt signaling in osteoblasts and osteocytes. This study suggests that using IL-17A blocking agents in psoriasis could be beneficial against bone loss in these patients. Copyright © 2016, American Association for the Advancement of Science.

Changes in the population of perivascular cells in the bone tissue remodeling zones under microgravity

NASA Astrophysics Data System (ADS)

Katkova, Olena; Rodionova, Natalia; Shevel, Ivan

2016-07-01

Microgravity and long-term hypokinesia induce reduction both in bone mass and mineral saturation, which can lead to the development of osteoporosis and osteopenia. (Oganov, 2003). Reorganizations and adaptive remodeling processes in the skeleton bones occur in the topographical interconnection with blood capillaries and perivascular cells. Radioautographic studies with 3H- thymidine (Kimmel, Fee, 1980; Rodionova, 1989, 2006) have shown that in osteogenesis zones there is sequential differentiation process of the perivascular cells into osteogenic. Hence the study of populations of perivascular stromal cells in areas of destructive changes is actual. Perivascular cells from metaphysis of the rat femoral bones under conditions of modeling microgravity were studied using electron microscopy and cytochemistry (hindlimb unloading, 28 days duration) and biosatellite «Bion-M1» (duration of flight from April 19 till May 19, 2013 on C57, black mice). It was revealed that both control and test groups populations of the perivascular cells are not homogeneous in remodeling adaptive zones. These populations comprise of adjacent to endothelium poorly differentiated forms and isolated cells with signs of differentiation (specific increased volume of rough endoplasmic reticulum in cytoplasm). Majority of the perivascular cells in the control group (modeling microgravity) reveals reaction to alkaline phosphatase (marker of the osteogenic differentiation). In poorly differentiated cells this reaction is registered in nucleolus, nucleous and cytoplasm. In differentiating cells activity of the alkaline phosphatase is also detected on the outer surface of the cellular membrane. Unlike the control group in the bones of experimental animals reaction to the alkaline phosphatase is registered not in all cells of perivascular population. Part of the differentiating perivascular cells does not contain a product of the reaction. Under microgravity some poorly differentiated perivascular cells reveal signs of destruction. Thus it was found that number of the alkaline phosphatase containing cells (i.e. osteogenic cells) declines in perivascular cells population. It is one of the mechanisms of the osteogenic process decrease of intensity in bones because of lessening support loading on the bone skeleton. In the adaptive remodeling zones of bone tissue (near the vascular canals) in experiments fibroblasts and fibrosis zones were found - areas filled with non-mineralized collagen fibrils on the bones surfaces. Hence it should be considered that decrease (removal) of support loading slows down osteogenic differentiation of the part of perivascular cells and stimulates differentiation of the fibroblast cells. Obtained data is considered as one of the cellular mechanisms of the adaptive reactions development in spongy bone under microgravity which could lead to the bone mass loss.

Serum markers of bone metabolism show bone loss in hibernating bears

USGS Publications Warehouse

Donahue, S.W.; Vaughan, M.R.; Demers, L.M.; Donahue, H.J.

2003-01-01

Disuse osteopenia was studied in hibernating black bears (Ursus americanus) using serum markers of bone metabolism. Blood samples were collected from male and female, wild black bears during winter denning and active summer periods. Radioimmunoassays were done to determine serum concentrations of cortisol, the carboxy-terminal cross-linked telopeptide, and the carboxy-terminal propeptide of Type I procollagen, which are markers of hone resorption and formation, respectively. The bone resorption marker was significantly higher during winter hibernation than it was in the active summer months, but the bone formation marker was unchanged, suggesting an imbalance in bone remodeling and a net bone loss during disuse. Serum cortisol was significantly correlated with the bone resorption marker, but not with the bone formation marker. The bone formation marker was four- to fivefold higher in an adolescent and a 17-year-old bear early in the remobilization period compared with the later summer months. These findings raise the possibility that hibernating black bears may minimize bone loss during disuse by maintaining osteoblastic function and have a more efficient compensatory mechanism for recovering immobilization-induced bone loss than that of humans or other animals.

Effects of Growth Hormone/IGF-I and Exercise on Unloaded Bones

NASA Technical Reports Server (NTRS)

Harper, J. S.; Arnaud, S. B.; Gosselink, K. L.; Grindeland, R. E.

1994-01-01

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) in combination with exercise prevent muscle atrophy induced by unloading in the tail-suspension rat model for space flight (Gosselink et al, FASEB J 1994). This study evaluated the effects of these treatments on bone. Hypophysectomized rats were suspended (S) and treated with 1mg/kg/day CH plus IGF-I (H) or vehicle (Sal) daily by injection and exercised (Ex) by 3 climbs up a 1m ladder carrying a load equal to 30% the initial body weight (BW) 3x/day for 10 days. Tibial epiphysis (Epi) widths were measured by micrometry and femoral Bone Mineral Content (fBMC) in excised femurs by DEXA (Lunar DPX-L). Serum calcium (Ca) and phosphorus (Pi) were measured by COBAS Autoanalyzer (Roche Diag.). Ambulatory (Amb)-H treated rats showed growth rates of 6.6+-0.9 g/day, similar to S-H-Ex and higher than S-H (3.210.6, p less than 0.05) and S-Sal (-0.711.0, p less than 0.05). Epi widths were 10% lower in S-Sal, and S-Sal-Ex, and increased 100% in all H groups. fBMC was less in S than Amb, only when all S groups are compared to both Amb groups (p less than 0.03). H treatment increased fBMC (p less than 0.05) but reduced fBMC/100g BW in all H groups (p less than 0.001). The reduced density of H bone cannot be attributed to low circulating Ca. and Pi since they were higher in H than Sal (p less than 0.001). H treatment for 10 days in doses sufficient to support normal growth in BW failed to produce normal Epi widths or fBMC, even when combined with exercise. The suspension effect observed in Epi widths was not corrected by H or Ex alone, but was improved by H plus a This regimen. although effective in preventing muscle atrophy, failed to return bone measures, Epi widths and fBMC, to normal.

Mechanical Signal Transduction in Countermeasures to Muscle Atrophy

NASA Technical Reports Server (NTRS)

Tidball, James G.; Chu, Amy (Technical Monitor)

2002-01-01

We have shown that modifications in muscle use result in changes in the expression and activity of calpains and nitric oxide synthase (NOS). Although muscle unloading for 10 days produced no change in the concentrations of calpain 1 or 2 and no change in calpain activation, muscle reloading produced a 90% increase in calpain 2 concentration. We developed an in vitro model to test our hypothesis that nitric oxide can inhibit cytoskeletal breakdown in skeletal muscle cells by inhibiting calpain cleavage of talin. Talin was selected because it is a well-characterized calpain substrate and it is codistributed with calpain in muscle cells. We found that intermittant loading during hindlimb suspension that is sufficient to prevent muscle mass loss that occurs during muscle unloading is also sufficient to prevent the decrease in NOS expression that normally occurs during hindlimb unloading. These findings indicate that therapeutics directed toward regulating the calpain/calpastatin system may be beneficial in preventing muscle mass loss in muscle injury, unloading and disease.

Biochemical response to chronic shortening in unloaded soleus muscles

NASA Technical Reports Server (NTRS)

Jaspers, S. R.; Fagan, J. M.; Tischler, M. E.

1985-01-01

One leg of tail-casted suspended rats was immobilized in a plantar-flexed position to test whether chronic shortening of posterior leg muscles affected the metabolic response to unloading. The immobilized plantaris and gastrocnemius muscles of these animals showed approximately 20 percent loss of muscle mass in contrast to simply a slower growth rate with unloading. Loss of mass of the soleus muscle during suspension was not accentuated by chronic shortening. Although protein degradation in the isolated soleus muscle of the plantar-flexed limb was slightly faster than in the contralateral free limb, this difference was offset by faster synthesis of the myofibrillar protein fraction of the chronically shortened muscle. Total adenine nucleotides were 17 percent lower (P less than 0.005) in the chronically shortened soleus muscle following incubation. Glutamate, glutamine, and alanine metabolism showed little response to chronic shortening. These results suggest that, in the soleus muscle, chronic shortening did not alter significantly the metabolic responses to unloading and reduced activity.

Large animal model for osteoporosis in humans: the ewe.

PubMed

Oheim, R; Amling, M; Ignatius, A; Pogoda, P

2012-11-12

Osteoporosis is a chronic systemic disease characterised by bone loss and microarchitectural deterioration. Since the underlying regulatory mechanisms are still not fully understood and treatment options are not satisfactorily resolved, massive efforts are underway to further investigate this critical illness. Large animal models are stipulated, e.g. by the Food and Drug Administration, for preclinical prevention and intervention studies related to osteoporosis research; in this context, the ewe has already proven its value for orthopaedic research. Although oestrogen deficiency doubtless influences bone metabolism in sheep, the ovariectomised ewe seems unsuitable as a model for postmenopausal osteoporosis and bone loss induction due to its unreliable impact on bone mass and structure. In contrast, glucocorticoid treatment has a major impact on bone turnover and leads to bone conditions comparable to those found in steroid-treated humans. However, adverse side effects can be dramatic resulting in unacceptable discomfort and illness of the experimental animals. Further improvements are therefore essential to judge this model as ethically appropriate. Additionally, models for osteoporosis induced by surgical interventions of central regulatory mechanisms seem to be attractive, as remarkable bone loss is induced by only one surgical procedure without any further treatment. Taken together, different ewe models for osteoporosis have been successfully established and are invaluable for orthopaedic research. However, the search for a 'perfect' large remodelling animal model - in terms of mimicking the human disease and compatibility of bone loss, and without ethical concerns - is still on-going.

Effect of an estrogen-deficient state and alendronate therapy on bone loss resulting from experimental periapical lesions in rats.

PubMed

Xiong, Haofei; Peng, Bin; Wei, Lili; Zhang, Xiaolei; Wang, Li

2007-11-01

The aim of the research was to evaluate the impact of an estrogen-deficient state and alendronate (ALD) therapy on bone loss resulting from experimental periapical lesions in rats. Periapical lesions were induced on ovariectomized (OVX) and sham-ovariectomized (Sham) rats. After sample preparation, histologic and radiographic examination for periapical bone loss area and an enzyme histochemical test for tartrate-resistant acid phosphatase (TRAP) were performed. The results showed that OVX significantly increased bone loss resulting from periradicular lesions. After daily subcutaneous injection of ALD, the bone loss area and the number of TRAP-positive cells (osteoclasts) were reduced. These findings suggested that alendronate may protect against increased bone loss from experimental periapical lesions in estrogen-deficient rats. Given recent recognition of adverse effects of bisphosphonates, including an increased risk for osteonecrosis, the findings from this study should not be interpreted as a new indication for ALD treatment. However, they may offer insight into understanding and predicting outcomes in female postmenopausal patients already on ALD therapy for medical indications.

Axial bone-socket displacement for persons with a traumatic transtibial amputation: The effect of elevated vacuum suspension at progressive body-weight loads.

PubMed

Darter, Benjamin J; Sinitski, Kirill; Wilken, Jason M

2016-10-01

Elevated vacuum suspension systems use a pump to draw air from the socket with the intent of reducing bone-socket motion as compared to passive suction systems. However, it remains unknown if elevated vacuum suspension systems decrease limb displacement uniformly during transitions from unloaded to full-body-weight support. To compare limb-socket motion between elevated vacuum and passive suction suspension sockets using a controlled loading paradigm. Comparative analysis. Persons with transtibial amputation were assessed while wearing either an elevated vacuum or passive suction suspension socket. Digital video fluoroscopy was used to measure axial bone-socket motion while the limb was loaded in 20% body-weight increments. An analysis of variance model was used to compare between suspension types. Total axial displacement (0%-100% body weight) was significantly lower using the elevated vacuum (vacuum: 1.3 cm, passive suction: 1.8 cm; p < 0.0001). Total displacement decreased primarily due to decreased motion during initial loading (0%-20%; p < 0.0001). Other body-weight intervals were not significantly different between systems. Elevated vacuum suspension reduced axial limb-socket motion by maintaining position of the limb within the socket during unloaded conditions. Elevated vacuum provided no meaningful improvement in limb-socket motion past initial loading. Excessive bone-socket motion contributes to poor residual limb health. Our results suggest elevated vacuum suspensions can reduce this axial displacement. Visual assessment of the images suggests that this occurs through the reduction or elimination of the air pocket between the liner and socket wall while the limb is unloaded. © The International Society for Prosthetics and Orthotics 2015.

Superoxide Dismutase Protects Osteoprogenitors from Irradiation with Low-LET but Not High-LET Species

NASA Technical Reports Server (NTRS)

Schreurs, A.-S.; Tran, L.; Alwood, J. S.; Tahimic, C. G.; Globus, R. K.

2016-01-01

Ionizing radiation-induced bone loss appears to be a two-stage process: first an early increase in pro-resorption cytokines and increased bone resorption by osteoclasts, followed by a decrease in bone formation by osteoblasts. This results in a net loss of mass in mineralized bone tissue. The molecular mechanisms underlying the imbalance in bone remodeling caused by exposure to radiation are not fully understood. We hypothesized that the radiation-induced rise in reactive oxygen species (ROS) damages osteoblast progenitors, leading to a decrease in number and activity of differentiated progeny. We have shown that a diet high in antioxidant capacity prevents radiation-induced bone loss in adult mice (Schreurs et al. 2016) by reducing the early increase in pro-resotption cytokines. Here, we investigated the damaging effects of radiation exposure on cells in the osteoblast lineage, testing if addition of the exogenous antioxidant enzyme, superoxide dismutase (SOD) can mitigate radiation damage. Osteoprogenitors were grown in vitro from the marrow of 16wk old, male C57Bl/6 mice. Cells were irradiated 3 days after plating (day 0) with either gamma (Cs-137, 0.1-5Gy) or iron (Fe-56, 600 MeV/n, 0.5-2Gy), and then grown until day 10. SOD or vehicle was added 2 hours before irradiation (SOD at 200U/ml), twice a day and up to day 5, for a total of 2 days treatment. Cell behavior was assessed by: (a) colony number (counted on day 7), (b) DNA content (surrogate for cell number) to assess cell growth (percent change between day 3 and day 10) and (c) alkaline phosphatase activity (osteoblast differentiation marker). Results show that SOD protected cells from the adverse effects of low-LET ionizing radiation, but not high-LET radiation. These novel results provide an interesting platform to explore further diverse effects and damages caused by low-LET and high-LET, pointing toward different mechanisms and possible intervention strategies for radiation-induced bone loss.

The Digital Astronaut Project Computational Bone Remodeling Model (Beta Version) Bone Summit Summary Report

NASA Technical Reports Server (NTRS)

Pennline, James; Mulugeta, Lealem

2013-01-01

Under the conditions of microgravity, astronauts lose bone mass at a rate of 1% to 2% a month, particularly in the lower extremities such as the proximal femur [1-3]. The most commonly used countermeasure against bone loss in microgravity has been prescribed exercise [4]. However, data has shown that existing exercise countermeasures are not as effective as desired for preventing bone loss in long duration, 4 to 6 months, spaceflight [1,3,5,6]. This spaceflight related bone loss may cause early onset of osteoporosis to place the astronauts at greater risk of fracture later in their lives. Consequently, NASA seeks to have improved understanding of the mechanisms of bone demineralization in microgravity in order to appropriately quantify this risk, and to establish appropriate countermeasures [7]. In this light, NASA's Digital Astronaut Project (DAP) is working with the NASA Bone Discipline Lead to implement well-validated computational models to help predict and assess bone loss during spaceflight, and enhance exercise countermeasure development. More specifically, computational modeling is proposed as a way to augment bone research and exercise countermeasure development to target weight-bearing skeletal sites that are most susceptible to bone loss in microgravity, and thus at higher risk for fracture. Given that hip fractures can be debilitating, the initial model development focused on the femoral neck. Future efforts will focus on including other key load bearing bone sites such as the greater trochanter, lower lumbar, proximal femur and calcaneus. The DAP has currently established an initial model (Beta Version) of bone loss due to skeletal unloading in femoral neck region. The model calculates changes in mineralized volume fraction of bone in this segment and relates it to changes in bone mineral density (vBMD) measured by Quantitative Computed Tomography (QCT). The model is governed by equations describing changes in bone volume fraction (BVF), and rates of changes in bone cell populations that remove and replace bone in packets within the bone region. The DAP bone model is unique in several respects. In particular in takes former models of volume fraction changes one step higher in fidelity and separates BVF into separate equations for mineralized and osteoid volume fractions governed by a mineralization rate. This more closely follows the physiology of the remodeling unit cycles where bone is first resorbed and then followed by the action of osteoblasts to lay down collagen matrix which eventually becomes mineralized. In another respect, the modules allow the functional description of the time rate of change of other parameters and variables in the model during a computational simulation. More detailed description of the model, preliminary validation results, current limitation and caveats, and planned advancements are provided in sections 2 through 5. The DAP bone model is being developed primarily as a research tool, and not as a clinical tool like QCT. Even if it transitions to a clinical tool, it is not intended to replace QCT or any other clinical tool. Moreover, the DAP bone model does not predict bone fracture. Its purpose is to provide valuable additional data via "forward prediction" simulations for during and after spaceflight missions to gain insight on, (1) mechanisms of bone demineralization in microgravity, and (2) the volumetric changes at the various bone sites in response to in-flight and post-flight exercise countermeasures. This data can then be used as input to the Keyak [8] (or equivalent) FE analysis method to gain insight on how bone strength may change during and after flight. This information can also be useful to help optimize exercise countermeasure protocols to minimize changes in bone strength during flight, and improve regain of bone strength post-flight. To achieve this goal, the bone model will be integrated with DAP's exercise countermeasure models to simulate the effect of exercise prescriptions on preserving bone. More specifically, the model will accept loading history due to muscle and joint force on bone and produce quantified remodeling within the bone region under influence of the applied stress. Furthermore, because they tend to respond differently, the bone remodeling model includes both trabecular bone and cortical bone.

Calcium and Bone Metabolism During Spaceflight

NASA Technical Reports Server (NTRS)

Smith, Scott M.

2002-01-01

The ability to understand and counteract weightlessness-induced bone loss will be critical for crew health and safety during and after space station or exploration missions lasting months or years, respectively. Until its deorbit in 2001 , the Mir Space Station provided a valuable platform for long-duration space missions and life sciences research. Long-duration flights are critical for studying bone loss, as the 2- to 3-week Space Shuttle flights are not long enough to detect changes in bone mass. This review will describe human spaceflight data, focusing on biochemical surrogates of bone and calcium metabolism. This subject has been reviewed previously. 1-

Biophotonics and Bone Biology

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory; Fischer, David; Asipauskas, Marius; Chauhan, Chirag; Compitello, Nicole; Burke, Jamie; Tate, Melissa Knothe

2004-01-01

One of the more serious side effects of extended space flight is an accelerated bone loss. Rates of bone loss are highest in the weight-bearing bones of the hip and spine regions, and the average rate of bone loss as measured by bone mineral density measurements is around 1.2% per month for persons in a microgravity environment. It is well known that bone remodeling responds to mechanical forces. We are developing two-photon microscopy techniques to study bone tissue and bone cell cultures to better understand the fundamental response mechanism in bone remodeling. Osteoblast and osteoclast cell cultures are being studied, and the goal is to use molecular biology techniques in conjunction with Fluorescence Lifetime Imaging Microscopy (FLIM) to study the physiology of in-vitro cell cultures in response to various stimuli, such as fluid flow induced shear stress and mechanical stress. We have constructed a two-photon fluorescence microscope for these studies, and are currently incorporating FLIM detection. Current progress will be reviewed. This work is supported by the NASA John Glenn Biomedical Engineering Consortium.

Betulinic acid, a bioactive pentacyclic triterpenoid, inhibits skeletal-related events induced by breast cancer bone metastases and treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Se Young; Kim, Hyun-Jeong; Kim, Ki Rim

Many breast cancer patients experience bone metastases and suffer skeletal complications. The present study provides evidence on the protective and therapeutic potential of betulinic acid on cancer-associated bone diseases. Betulinic acid is a naturally occurring triterpenoid with the beneficial activity to limit the progression and severity of cancer, diabetes, cardiovascular diseases, atherosclerosis, and obesity. We first investigated its effect on breast cancer cells, osteoblastic cells, and osteoclasts in the vicious cycle of osteolytic bone metastasis. Betulinic acid reduced cell viability and the production of parathyroid hormone-related protein (PTHrP), a major osteolytic factor, in MDA-MB-231 human metastatic breast cancer cells stimulatedmore » with or without tumor growth factor-β. Betulinic acid blocked an increase in the receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin ratio by downregulating RANKL protein expression in PTHrP-treated human osteoblastic cells. In addition, betulinic acid inhibited RANKL-induced osteoclastogenesis in murine bone marrow macrophages and decreased the production of resorbed area in plates with a bone biomimetic synthetic surface by suppressing the secretion of matrix metalloproteinase (MMP)-2, MMP-9, and cathepsin K in RANKL-induced osteoclasts. Furthermore, oral administration of betulinic acid inhibited bone loss in mice intra-tibially inoculated with breast cancer cells and in ovariectomized mice causing estrogen deprivation, as supported by the restored bone morphometric parameters and serum bone turnover markers. Taken together, these findings suggest that betulinic acid may have the potential to prevent bone loss in patients with bone metastases and cancer treatment-induced estrogen deficiency. - Highlights: • Betulinic acid reduced PTHrP production in human metastatic breast cancer cells. • Betulinic acid blocked RANKL/OPG ratio in PTHrP-stimulated human osteoblastic cells. • Betulinic acid inhibited RANKL-induced osteoclastogenesis in bone marrow macrophages. • Betulinic acid decreased bone resorption by suppressing osteoclast activity. • Orally administered betulinic acid inhibited cancer-associated bone diseases in mice.« less

Role of human amnion-derived mesenchymal stem cells in promoting osteogenic differentiation by influencing p38 MAPK signaling in lipopolysaccharide -induced human bone marrow mesenchymal stem cells.

PubMed

Wang, Yuli; Wu, Hongxia; Shen, Ming; Ding, Siyang; Miao, Jing; Chen, Ning

2017-01-01

Periodontitis is a chronic inflammatory disease induced by bacterial pathogens, which not only affect connective tissue attachments but also cause alveolar bone loss. In this study, we investigated the anti-inflammatory effects of Human amnion-derived mesenchymal stem cells (HAMSCs) on human bone marrow mesenchymal stem cells (HBMSCs) under lipopolysaccharide (LPS)-induced inflammatory conditions. Proliferation levels were measured by flow cytometry and immunofluorescence staining of 5-ethynyl-2'-deoxyuridine (EdU). Osteoblastic differentiation and mineralization were investigated using chromogenic alkaline phosphatase activity (ALP) activity substrate assays, Alizarin red S staining, and RT-PCR analysis of HBMSCs osteogenic marker expression. Oxidative stress induced by LPS was investigated by assaying reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity. Here, we demonstrated that HAMSCs increased the proliferation, osteoblastic differentiation, and SOD activity of LPS-induced HBMSCs, and down-regulated the ROS level. Moreover, our results suggested that the activation of p38 MAPK signal transduction pathway is essential for reversing the LPS-induced bone-destructive processes. SB203580, a selective inhibitor of p38 MAPK signaling, significantly suppressed the anti-inflammatory effects in HAMSCs. In conclusion, HAMSCs show a strong potential in treating inflammation-induced bone loss by influencing p38 MAPK signaling. Copyright © 2016 Elsevier Inc. All rights reserved.

A selective androgen receptor modulator that reduces prostate tumor size and prevents orchidectomy-induced bone loss in rats.

PubMed

Allan, George; Lai, Muh-Tsann; Sbriscia, Tifanie; Linton, Olivia; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Dodds, Robert; Fiordeliso, James; Lanter, James; Sui, Zhihua; Lundeen, Scott

2007-01-01

The pharmacological activity of JNJ-26146900 is described. JNJ-26146900 is a nonsteroidal androgen receptor (AR) ligand with tissue-selective activity in rats. The compound was evaluated in in vitro and in vivo models of AR activity. It binds to the rat AR with a K(i) of 400nM and acts as a pure androgen antagonist in an in vitro cell-based assay. Its in vitro profile is similar to the androgen antagonist bicalutamide (Casodex). In intact rats, JNJ-26146900 reduces ventral prostate weight with an oral potency (ED(50)) of 20-30mg/kg, again comparable to that of bicalutamide. JNJ-26146900 prevented prostate tumor growth in the Dunning rat model, maximally inhibiting growth at a dose of 10mg/kg. It slowed tumor growth significantly in a CWR22-LD1 mouse xenograft model of human prostate cancer. It was tested in aged male rats for its ability to prevent bone loss and loss of lean body mass following orchidectomy. After 6 weeks of dosing, bone volume decreased by 33% in orchidectomized versus intact vehicle-treated rats with a probability (P) of less than 0.05, as measured by micro-computerized tomography analysis. At a dose of 30mg/kg, JNJ-26146900 significantly reduced castration-induced tibial bone loss as indicated by the following parameters: bone volume, trabecular connectivity, trabecular number and spacing between trabeculae. Bone mineral density decreased from 229+/-34mg/cm(3) of hydroxyapatite to 166+/-26mg/cm(3) following orchidectomy, and was maintained at 194+/-20mg/cm(3) with JNJ-26146900 treatment (P<0.05 relative to orchidectomy alone). Using magnetic resonance imaging, the compound was found to partially prevent orchidectomy-induced loss of lean body mass. Our data show that selective androgen receptor modulators (SARMs) have the potential for anabolic effects on bone and muscle while maintaining therapeutic efficacy in prostate cancer.

Bisphosphonates Improve Trabecular Bone Mass and Normalize Cortical Thickness in Ovariectomized, Osteoblast Connexin43 Deficient Mice

PubMed Central

Watkins, Marcus P.; Norris, Jin Yi; Grimston, Susan K.; Zhang, Xiaowen; Phipps, Roger J.; Ebetino, Frank H.; Civitelli, Roberto

2012-01-01

The gap junction protein, connexin43 (Cx43) controls both bone formation and osteoclastogenesis via osteoblasts and/or osteocytes. Cx43 has also been proposed to mediate an anti-apoptotic effect of bisphosphonates, potent inhibitors of bone resorption. We studied whether bisphosphonates are effective in protecting mice with a conditional Cx43 gene deletion in osteoblasts and osteocytes (cKO) from the consequences of ovariectomy on bone mass and strength. Ovariectomy resulted in rapid loss of trabecular bone followed by a slight recovery in wild type (WT) mice, and a similar degree of trabecular bone loss, albeit slightly delayed, occurred in cKO mice. Treatment with either risedronate (20µg/kg) or alendronate (40µg/kg) prevented ovariectomy-induced bone loss in both genotypes. In basal conditions, bones of cKO mice have larger marrow area, higher endocortical osteoclast number, and lower cortical thickness and strength relative to WT. Ovariectomy increased endocortical osteoclast number in WT but not in cKO mice. Both bisphosphonates prevented these increases in WT mice, and normalized endocortical osteoclast number, cortical thickness and bone strength in cKO mice. Thus, lack of osteoblast/osteocyte Cx43 does not alter bisphosphonate action on bone mass and strength in estrogen deficiency. These results support the notion that one of the main functions of Cx43 in cortical bone is to restrain osteoblast and/or osteocytes from inducing osteoclastogenesis at the endocortical surface. PMID:22750450

The Protective Effect of Rhizoma Dioscoreae Extract against Alveolar Bone Loss in Ovariectomized Rats via Regulating Wnt and p38 MAPK Signaling

PubMed Central

Zhang, Zhiguo; Xiang, Lihua; Bai, Dong; Wang, Wenlai; Li, Yan; Pan, Jinghua; Liu, Hong; Wang, Shaojun; Xiao, Gary Guishan; Ju, Dahong

2014-01-01

Aim: The aim of this study was to evaluate the osteoprotective effect of aqueous Rhizoma Dioscoreae extract (RDE) on the alveolar bone of rats with ovariectomy-induced bone loss. Methods: Female Wistar rats were subjected to either ovariectomy or a sham operation (SHAM). The ovariectomized (OVX) rats were treated with vehicle (OVX) or RDE by oral gavage or with 17β-estradiol (E2) subcutaneously. After treatments, the bone mineral density (BMD), the three-dimensional bone architecture of the alveolar bone and the plasma biomarkers of bone turnover were analyzed to assess bone metabolism, and the histomorphometry of the alveolar bone was observed. Microarrays were used to evaluate gene expression profiles in alveolar bone from RDE-treated and OVX rats. The differential expression of genes was further analyzed using Ingenuity Pathway Analysis (IPA). The key findings were verified using real-time quantitative RT-PCR (qRT-PCR). Results: Our results showed that RDE inhibited alveolar bone loss in OVX rats. Compared to the OVX rats, the RDE-treated rats showed upregulated expression levels of 207 genes and downregulated expression levels of 176 genes in the alveolar bone. The IPA showed that several genes had the potential to code for proteins that were involved in the Wnt/β-catenin signaling pathway (Wnt7a, Fzd2, Tcf3, Spp1, Frzb, Sfrp2 and Sfrp4) and the p38 MAPK signaling pathway (Il1rn and Mapk14). Conclusion: These experiments revealed that RDE could inhibit ovariectomy-induced alveolar bone loss in rats. The mechanism of this anti-osteopenic effect in alveolar bone may be involved in the reduced abnormal bone remodeling, which is associated with the modulation of the Wnt/β-catenin and the p38 MAPK signaling pathways via gene regulation. PMID:25514564

Would Interstitial Fluid Flow be Responsible for Skeletal Maintenance in Tail-Suspended Rats?

NASA Astrophysics Data System (ADS)

Li, Wen-Ting; Huang, Yun-Fei; Sun, Lian-Wen; Luan, Hui-Qin; Zhu, Bao-Zhang; Fan, Yu-Bo

2017-02-01

Despite the fast development of manned space flight, the mechanism and countermeasures of weightlessness osteoporosis in astronauts are still within research. It is accepted that unloading has been considered as primary factor, but the precise mechanism is still unclear. Since bone's interstitial fluid flow (IFF) is believed to be significant to nutrient supply and waste metabolism of bone tissue, it may influence bone quality as well. We investigated IFF's variation in different parts of body (included parietal bone, ulna, lumbar, tibia and tailbone) of rats using a tail-suspended (TS) system. Ten female Sprague-Dawley (SD) rats were divided into two groups: control (CON) and tail-suspension (TS) group. And after 21 days' experiment, the rats were injected reactive red to observe lacuna's condition under a confocal laser scanning microscope. The variations of IFF were analyzed by the number and area of lacuna. Volumetric bone mineral density (vBMD) and microarchitecture of bones were evaluated by micro-CT. The correlation coefficients between lacuna's number/area and vBMD were also analyzed. According to our experimental results, a 21 days' tail-suspension could cause a decrease of IFF in lumbar, tibia and tailbone and an increase of IFF in ulna. But in parietal bone, it showed no significant change. The vBMD and microarchitecture parameters also decreased in lumbar and tibia and increased in ulna. But in parietal bone and tailbone, it showed no significant change. And correlation analysis showed significant correlation between vBMD and lacuna's number in lumbar, tibia and ulna. Therefore, IFF decrease may be partly contribute to bone loss in tail-suspended rats, and it should be further investigated.

Cancer-associated bone disease.

PubMed

Rizzoli, R; Body, J-J; Brandi, M-L; Cannata-Andia, J; Chappard, D; El Maghraoui, A; Glüer, C C; Kendler, D; Napoli, N; Papaioannou, A; Pierroz, D D; Rahme, M; Van Poznak, C H; de Villiers, T J; El Hajj Fuleihan, G

2013-12-01

Bone is commonly affected in cancer. Cancer-induced bone disease results from the primary disease, or from therapies against the primary condition, causing bone fragility. Bone-modifying agents, such as bisphosphonates and denosumab, are efficacious in preventing and delaying cancer-related bone disease. With evidence-based care pathways, guidelines assist physicians in clinical decision-making. Of the 57 million deaths in 2008 worldwide, almost two thirds were due to non-communicable diseases, led by cardiovascular diseases and cancers. Bone is a commonly affected organ in cancer, and although the incidence of metastatic bone disease is not well defined, it is estimated that around half of patients who die from cancer in the USA each year have bone involvement. Furthermore, cancer-induced bone disease can result from the primary disease itself, either due to circulating bone resorbing substances or metastatic bone disease, such as commonly occurs with breast, lung and prostate cancer, or from therapies administered to treat the primary condition thus causing bone loss and fractures. Treatment-induced osteoporosis may occur in the setting of glucocorticoid therapy or oestrogen deprivation therapy, chemotherapy-induced ovarian failure and androgen deprivation therapy. Tumour skeletal-related events include pathologic fractures, spinal cord compression, surgery and radiotherapy to bone and may or may not include hypercalcaemia of malignancy while skeletal complication refers to pain and other symptoms. Some evidence demonstrates the efficacy of various interventions including bone-modifying agents, such as bisphosphonates and denosumab, in preventing or delaying cancer-related bone disease. The latter includes treatment of patients with metastatic skeletal lesions in general, adjuvant treatment of breast and prostate cancer in particular, and the prevention of cancer-associated bone disease. This has led to the development of guidelines by several societies and working groups to assist physicians in clinical decision making, providing them with evidence-based care pathways to prevent skeletal-related events and bone loss. The goal of this paper is to put forth an IOF position paper addressing bone diseases and cancer and summarizing the position papers of other organizations.

R-Spondin 1 promotes vibration-induced bone formation in mouse models of osteoporosis

PubMed Central

Wang, Haitao; Brennan, Tracy A.; Russell, Elizabeth; Kim, Jung-Hoon; Egan, Kevin P.; Chen, Qijun; Israelite, Craig; Schultz, David C.; Johnson, Frederick B.; Pignolo, Robert J.

2013-01-01

Bone tissue adapts to its functional environment by optimizing its morphology for mechanical demand. Among the mechanosensitive cells that recognize and respond to forces in the skeleton are osteocytes, osteoblasts, and mesenchymal progenitor cells (MPCs). Therefore, the ability to use mechanical signals to improve bone health through exercise and devices that deliver mechanical signals is an attractive approach to age-related bone loss; however, the extracellular or circulating mediators of such signals are largely unknown. Using SDS-PAGE separation of proteins secreted by MPCs in response to low magnitude mechanical signals and in-gel trypsin digestion followed by HPLC and mass spectroscopy, we identified secreted proteins up-regulated by vibratory stimulation. We exploited a cell senescence-associated secretory phenotype screen, and reasoned that a subset of vibration-induced proteins with diminished secretion by senescent MPCs will have the capacity to promote bone formation in vivo. We identified one such vibration-induced bone-enhancing (vibe) gene as R-Spondin 1, a Wnt pathway modulator, and demonstrated that it has the capacity to promote bone formation in three mouse models of age-related bone loss. By virtue of their secretory status, some vibe proteins may be candidates for pre-clinical development as anabolic agents for the treatment of osteoporosis. PMID:23974989

Plasminogen activator inhibitor-1 deficiency ameliorates insulin resistance and hyperlipidemia but not bone loss in obese female mice.

PubMed

Tamura, Yukinori; Kawao, Naoyuki; Yano, Masato; Okada, Kiyotaka; Matsuo, Osamu; Kaji, Hiroshi

2014-05-01

We previously demonstrated that plasminogen activator inhibitor-1 (PAI-1), an inhibitor of fibrinolysis, is involved in type 1 diabetic bone loss in female mice. PAI-1 is well known as an adipogenic factor induced by obesity. We therefore examined the effects of PAI-1 deficiency on bone and glucose and lipid metabolism in high-fat and high-sucrose diet (HF/HSD)-induced obese female mice. Female wild-type (WT) and PAI-1-deficient mice were fed with HF/HSD or normal diet for 20 weeks from 10 weeks of age. HF/HSD increased the levels of plasma PAI-1 in WT mice. PAI-1 deficiency suppressed the levels of blood glucose, plasma insulin, and total cholesterol elevated by obesity. Moreover, PAI-1 deficiency improved glucose intolerance and insulin resistance induced by obesity. Bone mineral density (BMD) at trabecular bone as well as the levels of osterix, alkaline phosphatase, and receptor activator of nuclear factor κB ligand mRNA in tibia were decreased by HF/HSD in WT mice, and those changes by HF/HSD were not affected by PAI-1 deficiency. HF/HSD increased the levels of plasma TNF-α in both WT and PAI-1-deficient mice, and the levels of plasma TNF-α were negatively correlated with trabecular BMD in tibia of female mice. In conclusion, we revealed that PAI-1 deficiency does not affect the trabecular bone loss induced by obesity despite the amelioration of insulin resistance and hyperlipidemia in female mice. Our data suggest that the changes of BMD and bone metabolism by obesity might be independent of PAI-1 as well as glucose and lipid metabolism.

Effects of interleukin-7/interleukin-7 receptor on RANKL-mediated osteoclast differentiation and ovariectomy-induced bone loss by regulating c-Fos/c-Jun pathway.

PubMed

Zhao, Ji-Jun; Wu, Zhao-Feng; Yu, Ying-Hao; Wang, Ling; Cheng, Li

2018-09-01

To explore the effects of IL-7/IL-7R on the RANKL-mediated osteoclast differentiation in vitro and OVX-induced bone loss in vivo. BMMs and RAW264.7 were transfected with IL-7, IL-7R siRNA, c-Fos siRNA, and c-jun siRNA and later stimulated by RANKL. TRAP and toluidine blue staining were used to observe osteoclast formation and bone resorption, respectively. HE and TRAP staining were used to detect trabecular bone microstructure and osteoclasts of mice, respectively. qRT-PCR and Western blot analysis were used to examine expression. IL-7 unregulated the expression of CTSK, NFATc1, MMP9, and the phosphorylation of p38 and Akt by activating the c-Fos/c-Jun pathway, which increased osteoclast numbers and bone resorption in RANKL-stimulated macrophages. While IL-7R siRNA and c-Fos siRNA decreased the expression, as well as and the phosphorylation of p38 and Akt.IL-7 decreased the BMD and OPG expression in OVX-induced mice and increased the TRAP positive cells, the mRNA expression of c-fos, c-jun, and RANKL, which was contradictory to IL-7R siRNA, and c-Fos siRNA. Furthermore, IL-7R siRNA and c-Fos siRNA caused thicker trabeculae, increased trabecular number, and decreased osteolysis in OVX mice. IL-7/IL-7R can promote RANKL-mediated osteoclast formation and bone resorption by activating the c-Fos/c-Jun pathway, as well as inducing bone loss in OVX mice. © 2018 Wiley Periodicals, Inc.

Space Flight Calcium: Implications for Astronaut Health, Spacecraft Operations, and Earth

PubMed Central

Smith, Scott M.; McCoy, Torin; Gazda, Daniel; Morgan, Jennifer L. L.; Heer, Martina; Zwart, Sara R.

2012-01-01

The space flight environment is known to induce bone loss and, subsequently, calcium loss. The longer the mission, generally the more bone and calcium are lost. This review provides a history of bone and calcium studies related to space flight and highlights issues related to calcium excretion that the space program must consider so that urine can be recycled. It also discusses a novel technique using natural stable isotopes of calcium that will be helpful in the future to determine calcium and bone balance during space flight. PMID:23250146

Space flight calcium: implications for astronaut health, spacecraft operations, and Earth.

PubMed

Smith, Scott M; McCoy, Torin; Gazda, Daniel; Morgan, Jennifer L L; Heer, Martina; Zwart, Sara R

2012-12-18

The space flight environment is known to induce bone loss and, subsequently, calcium loss. The longer the mission, generally the more bone and calcium are lost. This review provides a history of bone and calcium studies related to space flight and highlights issues related to calcium excretion that the space program must consider so that urine can be recycled. It also discusses a novel technique using natural stable isotopes of calcium that will be helpful in the future to determine calcium and bone balance during space flight.

Tenuigenin inhibits RANKL-induced osteoclastogenesis by down-regulating NF-κB activation and suppresses bone loss in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Shuo; Department of Orthopedics, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan 410012; Li, Xianan

Tenuigenin, a major active component of polygala tenuifolia root, has been used to treat patients with insomnia, dementia, and neurosis. In this study, we aimed to investigate the effects of tenuigenin on osteoclastogenesis and clarify the possible mechanism. We showed that tenuigenin inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and bone resorption without cytotoxicity, which was further demonstrated by reduced osteoclast specific gene expression such as TRAP, c-Src, ATP6v0d2, etc. Moreover, the inhibitory effect of tenuigenin was associated with impaired NF-κB activity owing to delayed degradation/regeneration of IkBa and inhibition of p65 nuclear translocation. Consistent with themore » in vitro results, micro-ct scanning and analysis data showed that tenuigenin suppressed RANKL-induced bone loss in an animal model. Taken together, our data demonstrate that tenuigenin inhibit osteoclast formation and bone resorption both in vitro and in vivo, and comprise a potential therapeutic alternative for osteoclast-related disorders such as osteoporosis and cancer-induced bone destruction. - Highlights: • Tenuigenin suppresses osteoclasts formation, survival and function in vitro. • Tenuigenin impairs NF-κB activation. • Tenuigenin suppresses RANKL-induced bone lose in vivo. • Tenuigenin may be used for treating osteoclast related diseases.« less

Bisphosphonate as a Countermeasure to Space Flight-Induced Bone Loss

NASA Technical Reports Server (NTRS)

Spector, Elisabeth; LeBlanc, A.; Sibonga, J.; Matsumoto, T.; Jones, J.; Smith, S. M.; Shackelford, L.; Shapiro, J.; Lang, T.; Evans, H.;

Finite element simulation of Reference Point Indentation on bone.

PubMed

Idkaidek, Ashraf; Agarwal, Vineet; Jasiuk, Iwona

2017-01-01

Reference Point Indentation (RPI) is a novel technique aimed to assess bone quality. Measurements are recorded by the BioDent instrument that applies multiple indents to the same location of cortical bone. Ten RPI parameters are obtained from the resulting force-displacement curves. Using the commercial finite element analysis software Abaqus, we assess the significance of the RPI parameters. We create an axisymmetric model and employ an isotropic viscoelastic-plastic constitutive relation with damage to simulate indentations on a human cortical bone. Fracture of bone tissue is not simulated for simplicity. The RPI outputs are computed for different simulated test cases and then compared with experimental results, measured using the BioDent, found in literature. The number of cycles, maximum indentation load, indenter tip radius, and the mechanical properties of bone: Young׳s modulus, compressive yield stress, and viscosity and damage constants, are varied. The trends in the RPI parameters are then investigated. We find that the RPI parameters are sensitive to the mechanical properties of bone. An increase in Young׳s modulus of bone causes the force-displacement loading and unloading slopes to increase and the total indentation distance (TID) to decrease. The compressive yield stress is inversely proportional to a creep indentation distance (CID1) and the TID. The viscosity constant is proportional to the CID1 and an average of the energy dissipated (AvED). The maximum indentation load is proportional to the TID, CID1, loading and unloading slopes, and AvED. The damage parameter is proportional to the TID, but it is inversely proportional to both the loading and unloading slopes and the AvED. The value of an indenter tip radius is proportional to the CID1 and inversely proportional to the TID. The number of load cycles is inversely proportional to an average of a creep indentation depth (AvCID) and the AvED. The indentation distance increase (IDI) is strongly inversely proportional to the compressive yield stress, and strongly proportional to the viscosity constant and maximum applied load, but has weak relation with the damage parameter, indenter tip radius, and elastic modulus. This computational study advances our understanding of the RPI outputs and provides a starting point for more comprehensive computational studies of the RPI technique. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vitamin D supplementation protects against bone loss associated with chronic alcohol administration in female mice.

PubMed

Mercer, Kelly E; Wynne, Rebecca A; Lazarenko, Oxana P; Lumpkin, Charles K; Hogue, William R; Suva, Larry J; Chen, Jin-Ran; Mason, Andrew Z; Badger, Thomas M; Ronis, Martin J J

2012-11-01

Chronic alcohol abuse results in decreased bone mineral density (BMD), which can lead to increased fracture risk. In contrast, low levels of alcohol have been associated with increased BMD in epidemiological studies. Alcohol's toxic skeletal effects have been suggested to involve impaired vitamin D/calcium homeostasis. Therefore, dietary vitamin D supplementation may be beneficial in reducing bone loss associated with chronic alcohol consumption. Six-week-old female C57BL/6J mice were pair-fed ethanol (EtOH)-containing liquid diets (10 or 36% total calories) for 78 days. EtOH exposure at 10% calories had no effects on any measured bone or serum parameter. EtOH consumption at 36% of calories reduced BMD and bone strength (P<0.05), decreased osteoblastogenesis, increased osteoclastogenesis, suppressed 1,25-hydroxyvitamin D3 [1,25(OH)2D3] serum concentrations (P<0.05), and increased apoptosis in bone cells compared with pair-fed controls. In a second study, female mice were pair-fed 30% EtOH diets with or without dietary supplementation with vitamin D3 (cholecalciferol; VitD) for 40 days. VitD supplementation in the EtOH diet protected against cortical bone loss, normalized alcohol-induced hypocalcaemia, and suppressed EtOH-induced expression of receptor of nuclear factor-κB ligand mRNA in bone. In vitro, pretreatment of 1,25(OH)2D3 in osteoblastic cells inhibited EtOH-induced apoptosis. In EtOH/VitD mice circulating 1,25(OH)2D3 was lower compared with mice receiving EtOH alone (P<0.05), suggesting increased sensitivity to feedback control of VitD metabolism in the kidney. These findings suggest dietary VitD supplementation may prevent skeletal toxicity in chronic drinkers by normalizing calcium homeostasis, preventing apoptosis, and suppressing EtOH-induced increases in bone resorption.

Intrauterine stress induces bone loss in adult offspring of C3H/HeJ mice having high bone mass phenotype but not C57BL/6J mice with low bone mass phenotype.

PubMed

Raygorodskaya, M; Gabet, Y; Shochat, C; Kobyliansky, E; Torchinsky, A; Karasik, D

2016-06-01

In this study we examined to what extent and how genetics may modify osteoporosis risk arising due to environmental stresses which act during the antenatal period of life and have the potential to induce bone loss in adulthood. C57Bl/6J (C57) and C3H/HeJ (C3H) mice were used as a model system. The mice were exposed to a single injection of 5-aza-2'-deoxycytidine (5-AZA) on day 10 of pregnancy and the structure and bone mineral density (BMD) of the femur and 3rd lumbar vertebra of 3- and 6-month-old male and female offspring were evaluated by micro-computed tomography (μCT). Besides, we also attempted to evaluate whether 5-AZA affects the expression of some osteogenic genes in the embryonic limb buds. The main observation of this study is that 5-AZA-induced loss of bone quality was registered in 6-mo-old C3H offspring but not in their C57 counterparts. We also observed that C57 and C3H embryos may differ in their response to 5-AZA-induced detrimental stimuli: whereas 5-AZA treated C3H embryos exhibited a decreased expression of Col1a1, C57 embryos exhibit a decreased expression of Sox9. Overall, our study, by thorough characterization of bone homeostasis in 3- and 6-month-old offspring of 5-AZA-exposed C57 and C3H mice, allows hypothesizing that the adaptive response to antenatal insults may be stronger in offspring inherently exhibiting a low bone mass phenotype than in offspring inherently exhibiting a high bone mass phenotype. Copyright © 2016 Elsevier Inc. All rights reserved.

Morpho-histological assessment of the periodontal support structures under the action of excessive occlusal forces and under the influence of nicotine.

PubMed

Ispas, Ana; Mihu, Carmen Mihaela; Crăciun, Antarinia Maria; Constantiniuc, Mariana

2018-01-01

Smoking and occlusal trauma are two factors that can interfere with bone homeostasis. The aim of this study was to evaluate the histocellular changes occurring in the periodontal ligament and alveolar bone during the action of excessive occlusal forces, and to assess the influence of nicotine on the alveolar bone loss in teeth subjected to occlusal trauma. Fifty-six Wistar rats were randomized into seven groups (n=8). Animals were exposed to nicotine and occlusal trauma for 7, 14 and 30 days. Three groups were exposed to occlusal trauma alone, another three groups were exposed to occlusal trauma and nicotine, and one group was not exposed to any treatment. Periodontal lesions induced in the first stage (7-14 days) manifested by a moderate increase of the periodontal space, a multiplication, thickening and elongation of periodontal fibers, as well as their condensation in the middle area of the periradicular space. Regarding bone changes induced by occlusal trauma, groups 5 and 7 (occlusal trauma and nicotine administration) had higher bone losses compared to groups 1, 2, 3, 4 and 6. This study demonstrated that nicotine significantly affected the alveolar bone. The induced occlusal trauma caused obvious tissue damage. At the same time, it was found that nicotine enhanced alveolar bone resorption, increased tooth mobility and induced an exacerbation of inflammatory processes.

DC-STAMP Is an Osteoclast Fusogen Engaged in Periodontal Bone Resorption

PubMed Central

Wisitrasameewong, W.; Kajiya, M.; Movila, A.; Rittling, S.; Ishii, T.; Suzuki, M.; Matsuda, S.; Mazda, Y.; Torruella, M.R.; Azuma, M.M.; Egashira, K.; Freire, M.O.; Sasaki, H.; Wang, C.Y.; Han, X.; Taubman, M.A.; Kawai, T.

2017-01-01

Dendritic cell-specific transmembrane protein (DC-STAMP) plays a key role in the induction of osteoclast (OC) cell fusion, as well as DC-mediated immune regulation. While DC-STAMP gene expression is upregulated in the gingival tissue with periodontitis, its pathophysiological roles in periodontitis remain unclear. To evaluate the effects of DC-STAMP in periodontitis, anti-DC-STAMP–monoclonal antibody (mAb) was tested in a mouse model of ligature-induced periodontitis (n = 6–7/group) where Pasteurella pneumotropica (Pp)-reactive immune response activated T cells to produce receptor activator of nuclear factor kappa-B ligand (RANKL), which, in turn, promotes the periodontal bone loss via upregulation of osteoclastogenesis. DC-STAMP was expressed on the cell surface of mature multinuclear OCs, as well as immature mononuclear OCs, in primary cultures of RANKL-stimulated bone marrow cells. Anti-DC-STAMP-mAb suppressed the emergence of large, but not small, multinuclear OCs, suggesting that DC-STAMP is engaged in the late stage of cell fusion. Anti-DC-STAMP-mAb also inhibited pit formation caused by RANKL-stimulated bone marrow cells. Attachment of ligature to a second maxillary molar induced DC-STAMP messenger RNA and protein, along with elevated tartrate-resistant acid phosphatase–positive (TRAP+) OCs and alveolar bone loss. As we expected, systemic administration of anti-DC-STAMP-mAb downregulated the ligature-induced alveolar bone loss. Importantly, local injection of anti-DC-STAMP-mAb also suppressed alveolar bone loss and reduced the total number of multinucleated TRAP+ cells in mice that received ligature attachment. Attachment of ligature induced significantly elevated tumor necrosis factor–α, interleukin-1β, and RANKL in the gingival tissue compared with the control site without ligature (P < 0.05), which was unaffected by local injection with either anti-DC-STAMP-mAb or control-mAb. Neither in vivo anti-Pp IgG antibody nor in vitro anti-Pp T-cell response and resultant production of RANKL was affected by anti-DC-STAMP-mAb. This study illustrated the roles of DC-STAMP in promoting local OC cell fusion without affecting adaptive immune responses to oral bacteria. Therefore, it is plausible that a novel therapeutic regimen targeting DC-STAMP could suppress periodontal bone loss. PMID:28199142

Effects of raloxifene against letrozole-induced bone loss in chemically-induced model of menopause in mice.

PubMed

Kalam, Abul; Talegaonkar, Sushama; Vohora, Divya

2017-01-15

The deleterious effects of letrozole, an aromatase inhibitor, used in the adjuvant treatment of breast cancer in postmenopausal women, on bone are well-documented and represent a major drawback to its clinical use. Raloxifene, a selective estrogen receptor modulator and a clinically approved anti-osteoporotic drug, has been recently demonstrated to be efficacious in women with breast cancer. The present study evaluated the effects of preventive and curative treatment with raloxifene on letrozole-induced alterations of bone microarchitecture and turnover markers in a chemically-induced menopause model in mice. Swiss strain albino female mice were made menopausal by inducing ovotoxicity using vinyl cyclohexene di epoxide (VCD, 160 mg/kg for 15 days followed by 30 days drug-free period) confirmed by ovarian histology and serum estradiol levels. Effects on femoral and lumbar bones were evaluated by micro CT determination of bone volume, trabecular number, separation, thickness, connective density and trabecular pattern factor and bone turnover markers including ALP, TRAP5b, hydroxyproline and RANKL. In addition to these, markers of Wnt signaling (sclerostin and dickkopf-1) were also evaluated. To rule out the involvement of pharmacokinetic interaction, plasma levels of letrozole and raloxifene were measured following drugs alone and in combination. Though bone loss was observed in VCD treated mice (as indicated by micro CT measurements), it was further enhanced with letrozole administration (1 mg/kg) for one month particularly in epiphysis of femoral bones. Raloxifene (15 mg/kg), whether administered concurrently or post-letrozole was able to revert the structural alterations and changes in turnover markers caused by letrozole to varying degrees (p < 0.01 or p < 0.001). Further, estrogen deficiency following letrozole treatment in ovotoxic mice was associated with significant increase in sclerostin and dickkopf-1 in both lumbar and femur bones (p < 0.001) which was attenuated with preventive and curative treatment with raloxifene (p < 0.05). The plasma levels of letrozole remained unaffected by raloxifene administration and vice versa. Our study indicates the potential of raloxifene in preventing and attenuating letrozole-induced bone loss. Further, these effects were found to be independent of a pharmacokinetic interaction between the two drugs. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

IL-20 bone diseases involvement and therapeutic target potential.

PubMed

Wang, Hsiao-Hsuan; Hsu, Yu-Hsiang; Chang, Ming-Shi

2018-04-24

Millions of people around the world suffer from bone disorders, likes osteoporosis, rheumatoid arthritis (RA), and cancer-induced osteolysis. In general, the bone remodeling balance is determined by osteoclasts and osteoblasts, respectively responsible for bone resorption and bone formation. Excessive inflammation disturbs the activities of these two kinds of cells, typically resulting in the bone loss. IL-20 is emerging as a potent angiogenic, chemotactic, and proinflammatory cytokine related to several chronic inflammatory disorders likes psoriasis, atherosclerosis, cancer, liver fibrosis, and RA. IL-20 has an important role in the regulation of osteoclastogenesis and osteoblastogenesis and is upregulated in several bone-related diseases. The anti-IL-20 monoclonal antibody treatment has a therapeutic potential in several experimental disease models including ovariectomy-induced osteoporosis, cancer-induced osteolysis, and bone fracture. This review article provides an overview describing the IL-20's biological functions in the common bone disorders and thus providing a novel therapeutic strategy in the future.

Modeling Calcium Loss from Bones During Space Flight

NASA Technical Reports Server (NTRS)

Wastney, Meryl E.; Morukov, Boris V.; Larina, Irina M.; Abrams, Steven A.; Nillen, Jeannie L.; Davis-Street, Janis E.; Lane, Helen W.; Smith, Scott M.; Paloski, W. H. (Technical Monitor)

1999-01-01

Calcium loss from bones during space flight creates a risk for astronauts who travel into space, and may prohibit space flights to other planets. The problem of calcium loss during space flight has been studied using animal models, bed rest (as a ground-based model), and humans in-flight. In-flight studies have typically documented bone loss by comparing bone mass before and after flight. To identify changes in metabolism leading to bone loss, we have performed kinetic studies using stable isotopes of calcium. Oral (Ca-43) and intravenous (Ca-46) tracers were administered to subjects (n=3), three-times before flight, once in-flight (after 110 days), and three times post-flight (on landing day, and 9 days and 3 months after flight). Samples of blood, saliva, urine, and feces were collected for up to 5 days after isotope administration, and were analyzed for tracer enrichment. Tracer data in tissues were analyzed using a compartmental model for calcium metabolism and the WinSAAM software. The model was used to: account for carryover of tracer between studies, fit data for all studies using the minimal number of changes between studies, and calculate calcium absorption, excretion, bone calcium deposition and bone calcium resorption. Results showed that fractional absorption decreased by 50% during flight and that bone resorption and urinary excretion increased by 50%. Results were supported by changes in biochemical markers of bone metabolism. Inflight bone loss of approximately 250 mg Ca/d resulted from decreased calcium absorption combined with increased bone resorption and excretion. Further studies will assess the time course of these changes during flight, and the effectiveness of countermeasures to mitigate flight-induced bone loss. The overall goal is to enable human travel beyond low-Earth orbit, and to allow for better understanding and treatment of bone diseases on Earth.

The Ubiquitin Ligase Nedd4-1 Participates in Denervation-Induced Skeletal Muscle Atrophy in Mice

PubMed Central

Nagpal, Preena; Plant, Pamela J.; Correa, Judy; Bain, Alexandra; Takeda, Michiko; Kawabe, Hiroshi; Rotin, Daniela; Bain, James R.; Batt, Jane A. E.

2012-01-01

Skeletal muscle atrophy is a consequence of muscle inactivity resulting from denervation, unloading and immobility. It accompanies many chronic disease states and also occurs as a pathophysiologic consequence of normal aging. In all these conditions, ubiquitin-dependent proteolysis is a key regulator of the loss of muscle mass, and ubiquitin ligases confer specificity to this process by interacting with, and linking ubiquitin moieties to target substrates through protein∶protein interaction domains. Our previous work suggested that the ubiquitin-protein ligase Nedd4-1 is a potential mediator of skeletal muscle atrophy associated with inactivity (denervation, unloading and immobility). Here we generated a novel tool, the Nedd4-1 skeletal muscle-specific knockout mouse (myoCre;Nedd4-1flox/flox) and subjected it to a well validated model of denervation induced skeletal muscle atrophy. The absence of Nedd4-1 resulted in increased weights and cross-sectional area of type II fast twitch fibres of denervated gastrocnemius muscle compared with wild type littermates controls, at seven and fourteen days following tibial nerve transection. These effects are not mediated by the Nedd4-1 substrates MTMR4, FGFR1 and Notch-1. These results demonstrate that Nedd4-1 plays an important role in mediating denervation-induced skeletal muscle atrophy in vivo. PMID:23110050

Protective effects of the angiotensin type 1 receptor antagonist losartan in infection-induced and arthritis-associated alveolar bone loss.

PubMed

Queiroz-Junior, C M; Silveira, K D; de Oliveira, C R; Moura, A P; Madeira, M F M; Soriani, F M; Ferreira, A J; Fukada, S Y; Teixeira, M M; Souza, D G; da Silva, T A

2015-12-01

The angiotensin type 1 (AT1) receptor has been implicated in the pathogenesis of inflammatory bone disorders. This study aimed to investigate the effect of an AT1 receptor antagonist in infection-induced and arthritis-associated alveolar bone loss in mice. Mice were subjected to Aggregatibacter actinomycetemcomitans oral infection or antigen-induced arthritis and treated daily with 10 mg/kg of the prototype AT1 antagonist, losartan. Treatment was conducted for 30 d in the infectious condition and for 17 d and 11 d in the preventive or therapeutic regimens in the arthritic model, respectively. The mice were then killed, and the maxillae, serum and knee joints were collected for histomorphometric and immunoenzymatic assays. In vitro osteoclast assays were performed using RAW 264.7 cells stimulated with A. actinomycetemcomitans lipopolysacharide (LPS). Arthritis and A. actinomycetemcomitans infection triggered significant alveolar bone loss in mice and increased the levels of myeloperoxidase and of TRAP(+) osteoclasts in periodontal tissues. Losartan abolished such a phenotype, as well as the arthritis joint inflammation. Both arthritis and A. actinomycetemcomitans conditions were associated with the release of tumor necrosis factor alpha (TNF-α), interferon-gamma, interleukin-17 and chemokine (C-X-C motif) ligand 1 and an increased RANKL/osteoprotegerin ratio in periodontal tissues, but such expression decreased after losartan treatment, except for TNF-α. The therapeutic approach was as beneficial as the preventive one. In vitro, losartan prevented LPS-induced osteoclast differentiation and activity. The blockade of AT1 receptor exerts anti-inflammatory and anti-osteoclastic effects, thus protecting periodontal tissues in distinct pathophysiological conditions of alveolar bone loss. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

NELL-1 in the treatment of osteoporotic bone loss

DOE PAGES

James, Aaron W.; Shen, Jia; Zhang, Xinli; ...

2015-06-17

NELL-1 is a secreted, osteoinductive protein whose expression rheostatically controls skeletal ossification. Overexpression of NELL-1 results in craniosynostosis in humans and mice, whereas lack of Nell-1 expression is associated with skeletal undermineralization. Here we show that Nell-1-haploinsufficient mice have normal skeletal development but undergo age-related osteoporosis, characterized by a reduction in osteoblast: osteoclast (OB:OC) ratio and increased bone fragility. Recombinant NELL-1 binds to integrin β1 and consequently induces Wnt/β-catenin signalling, associated with increased OB differentiation and inhibition of OC-directed bone resorption. Systemic delivery of NELL-1 to mice with gonadectomy-induced osteoporosis results in improved bone mineral density. When extended to amore » large animal model, local delivery of NELL-1 to osteoporotic sheep spine leads to significant increase in bone formation. Furthermore, these findings suggest that NELL-1 deficiency plays a role in osteoporosis and demonstrate the potential utility of NELL-1 as a combination anabolic/antiosteoclastic therapeutic for bone loss.« less

NELL-1 in the treatment of osteoporotic bone loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, Aaron W.; Shen, Jia; Zhang, Xinli

NELL-1 is a secreted, osteoinductive protein whose expression rheostatically controls skeletal ossification. Overexpression of NELL-1 results in craniosynostosis in humans and mice, whereas lack of Nell-1 expression is associated with skeletal undermineralization. Here we show that Nell-1-haploinsufficient mice have normal skeletal development but undergo age-related osteoporosis, characterized by a reduction in osteoblast: osteoclast (OB:OC) ratio and increased bone fragility. Recombinant NELL-1 binds to integrin β1 and consequently induces Wnt/β-catenin signalling, associated with increased OB differentiation and inhibition of OC-directed bone resorption. Systemic delivery of NELL-1 to mice with gonadectomy-induced osteoporosis results in improved bone mineral density. When extended to amore » large animal model, local delivery of NELL-1 to osteoporotic sheep spine leads to significant increase in bone formation. Furthermore, these findings suggest that NELL-1 deficiency plays a role in osteoporosis and demonstrate the potential utility of NELL-1 as a combination anabolic/antiosteoclastic therapeutic for bone loss.« less

Simulating the Lunar Environment: Partial Weightbearing and High-LET Radiation-Induce Bone Loss and Increase Sclerostin-Positive Osteocytes.

PubMed

Macias, B R; Lima, F; Swift, J M; Shirazi-Fard, Y; Greene, E S; Allen, M R; Fluckey, J; Hogan, H A; Braby, L; Wang, Suojin; Bloomfield, S A

2016-09-01

Exploration missions to the Moon or Mars will expose astronauts to galactic cosmic radiation and low gravitational fields. Exposure to reduced weightbearing and radiation independently result in bone loss. However, no data exist regarding the skeletal consequences of combining low-dose, high-linear energy transfer (LET) radiation and partial weightbearing. We hypothesized that simulated galactic cosmic radiation would exacerbate bone loss in animals held at one-sixth body weight (G/6) without radiation exposure. Female BALB/cByJ four-month-old mice were randomly assigned to one of the following treatment groups: 1 gravity (1G) control; 1G with radiation; G/6 control; and G/6 with radiation. Mice were exposed to either silicon-28 or X-ray radiation. (28)Si radiation (300 MeV/nucleon) was administered at acute doses of 0 (sham), 0.17 and 0.5 Gy, or in three fractionated doses of 0.17 Gy each over seven days. X radiation (250 kV) was administered at acute doses of 0 (sham), 0.17, 0.5 and 1 Gy, or in three fractionated doses of 0.33 Gy each over 14 days. Bones were harvested 21 days after the first exposure. Acute 1 Gy X-ray irradiation during G/6, and acute or fractionated 0.5 Gy (28)Si irradiation during 1G resulted in significantly lower cancellous mass [percentage bone volume/total volume (%BV/TV), by microcomputed tomography]. In addition, G/6 significantly reduced %BV/TV compared to 1G controls. When acute X-ray irradiation was combined with G/6, distal femur %BV/TV was significantly lower compared to G/6 control. Fractionated X-ray irradiation during G/6 protected against radiation-induced losses in %BV/TV and trabecular number, while fractionated (28)Si irradiation during 1G exacerbated the effects compared to single-dose exposure. Impaired bone formation capacity, measured by percentage mineralizing surface, can partially explain the lower cortical bone thickness. Moreover, both partial weightbearing and (28)Si-ion exposure contribute to a higher proportion of sclerostin-positive osteocytes in cortical bone. Taken together, these data suggest that partial weightbearing and low-dose, high-LET radiation negatively impact maintenance of bone mass by lowering bone formation and increasing bone resorption. The impaired bone formation response is associated with sclerostin-induced suppression of Wnt signaling. Therefore, exposure to low-dose, high-LET radiation during long-duration spaceflight missions may reduce bone formation capacity, decrease cancellous bone mass and increase bone resorption. Future countermeasure strategies should aim to restore mechanical loads on bone to those experienced in one gravity. Moreover, low-doses of high-LET radiation during long-duration spaceflight should be limited or countermeasure strategies employed to mitigate bone loss.

Alendronate as an Effective Countermeasure to Disuse Induced Bone loss

NASA Technical Reports Server (NTRS)

LeBlanc, Adrian D.; Driscol, Theda B.; Shackelford, Linda C.; Evans, Harlan J.; Rianon, Nahid J.; Smith, Scott M.; Lai, Dejian

2002-01-01

Microgravity, similar to diuse immobilization on earth, causes rapid bone loss. This loss is believed to be an adaptive response to the reduced musculoskelatal forces in space and occurs gradually enough that changes occurring during short duration space flight are not a concern. Bone loss, however, will be a major impediment for long duration missions if effective countermeasures are not developed and implemented. Bed rest is used to simulate the reduced mechanical forces in humans and was used to test the hypothesis that oral alendronate would reduce the effects of long duration (17 weeks) inactivity on bone. Eight male subjects were given daily oral doses of alendronate during 17 weeks of horizontal bed rest and compared with 13 male control subjects not given the drug. Efficacy was evaluated based on measurements of bone markers, calcium balance and bone density performed before, during and after the bed rest. The results show that oral alendronate attenuates most of the characteristic changes associated with long duration bed rest and presumably space flight.

Does milling one-piece titanium dental implants induce osteocyte and osteoclast changes?

PubMed

Russe, P; Pascaretti-Grizon, F; Aguado, E; Goyenvale, E; Filmon, R; Baslé, M-F; Chappard, D

2011-06-01

One-piece dental implants avoid adverse effects sometimes associated with the traditional implant-abutment interface and may provide a suitable alternative to two-piece implants; however, one-piece implants often need in situ milling, which may exacerbate cell apoptosis from excessive heat at the bone-implant interface and induce secondary crestal bone loss. Twelve implants were placed in the metaphyses of two sheep under general anesthesia. Six implants were milled with a diamond bur while the other six implants remained intact. Animals were euthanized after four days, and bone blocks were harvested. Bone samples were studied without decalcification. Osteocytes were stained with Hoechst 33342 and osteoclasts by the TRAcP reaction. Both cell types, in the cortical and trabecular bone around the implant's cervical region, were counted utilizing morphometric methods. Values were compared to areas at a distance from the cervical region. No difference was observed between milled and unmilled implants, which suggested that the amount of generated heat did not provoke osteocyte loss or induce osteoclastogenesis. Intraoral abutment preparations did not increase cellular apoptosis at the bone-implant interface after four days in the ovine model. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

EFFECT OF MECHANICAL STIMULI ON SKELETAL REGENERATION AROUND IMPLANTS

PubMed Central

Leucht, Philipp; Kim, Jae-Beom; Wazen, Rima; Currey, Jennifer A.; Nanci, Antonio; Brunski, John B.; Helms, Jill A.

2007-01-01

Due to the aging population and the increasing need for total joint replacements, osseointegration is of a great interest for various clinical disciplines. Our objective was to investigate the molecular and cellular foundation that underlies this process. Here, we used an in vivo mouse model to study the cellular and molecular response in three distinct areas of unloaded implants: the periosteum, the gap between implant and cortical bone, and the marrow space. Our analyses began with the early phases of healing, and continued until the implants were completely osseointegrated. We investigated aspects of osseointegration ranging from vascularization, cell proliferation, differentiation, and bone remodeling. In doing so, we gained an understanding of the healing mechanisms of different skeletal tissues during unloaded implant osseointegration. To continue our analysis, we used a micromotion device to apply a defined physical stimulus to the implants, and in doing so, we dramatically enhanced bone formation in the peri-implant tissue. By comparing strain measurements with cellular and molecular analyses, we developed an understanding of the correlation between strain magnitudes and fate decisions of cells shaping the skeletal regenerate. PMID:17175211

Alendronate and Resistive Exercise Countermeasures Against Bed Rest-Induced Bone Loss: Biochemical Markers of Bone and Calcium Metabolism

NASA Technical Reports Server (NTRS)

Smith, Scott M.; Nillen, Jeannie L.; Davis-Street, Janis E.; DeKerlegand, Diane E.; LeBlanc, Adrian; Shackelford, Linda C.

2001-01-01

Weightlessness-induced bone loss must be counteracted to ensure crew health during extendedduration space missions. Studies were conducted to assess two bone loss countermeasures in a ground-based model: horizontal bed rest. Following a 3-wk ambulatory adaptation period, male and female subjects (aged 21-56 y) completed a 17-wk bed rest protocol. Subjects were assigned to one of three treatments: alendronate (ALEN; 10 mg/d, n=6), resistive exercise (RE; 1.5 h/d, 6 d/wk, n=8), or control (CN; no countermeasure, n=8). Dietary intake was adjusted to maintain body weight. Endocrine and biochemical indices were measured in blood and urine using standard laboratory methods. All data reported are expressed as percent change from individual pre-bedrest data. Serum calcium changed little during bed rest, and tended to decrease (4-8%) in ALEN subjects. In RE subjects, bone alkaline phosphatase and osteocalcin were increased >65 and >30%, respectively, during bed rest, while these were unchanged or decreased in ALEN and CN subjects. Urinary calcium was increased 50% in CN subjects, but was unchanged or decreased in both ALEN and RE groups. Urinary n-telopeptide excretion was increased 40-50% in CN and RE subjects, but decreased 20% in ALEN subjects. Pyridinium crosslink and deoxypyridinoline excretion were increased 20-50% during bed rest. These data suggest that RE countermeasures are effective at increasing markers of bone formation in an analog of weightlessness, while ALEN reduces markers of bone resorption. Counteracting the bone loss of space flight may require both pharmacologic and exercise countermeasures.

Inhibitory effects of a bisphosphonate (risedronate) on experimental periodontitis in rats.

PubMed

Shoji, K; Horiuchi, H; Shinoda, H

1995-07-01

The present study was designed to examine whether systemic administration of a bisphosphonate, risedronate, could prevent alveolar bone resorption in rats with experimental periodontitis. On Day 1, an elastic ring was placed around the neck of the right mandibular 1st molar to induce inflammatory periodontitis. The animals were given daily injections of either 0.9% NaCl (control group), or 0.8, 1.6 or 3.2 mumoles/kg (s.c.) of risedronate (experimental groups) from Days 1 to 7, and were killed on Day 8. Histological examinations and determination of bone mineral density in the interdental area between the 1st and 2nd molars with an image analyzer revealed that the presence of the elastic ring induced a loss of attachment and bone resorption in the control group. Vigorous bone resorption, with appearance of a large number of osteoclasts, was observed in the interdental and bifurcation areas. In the experimental groups, however, the resorption of alveolar bone and the loss of bone mineral content in these areas were prevented in a dose-dependent fashion, especially at doses of 1.6 and 3.2 mumoles/kg. Many osteoclasts were detached from the surface of the alveolar bone and had degenerated appearances, such as rounded shapes, loss of polarity and pyknosis. These results suggest that administration of risedronate is effective in preventing bone resorption in periodontitis.

Forces associated with launch into space do not impact bone fracture healing.

PubMed

Childress, Paul; Brinker, Alexander; Gong, Cynthia-May S; Harris, Jonathan; Olivos, David J; Rytlewski, Jeffrey D; Scofield, David C; Choi, Sungshin Y; Shirazi-Fard, Yasaman; McKinley, Todd O; Chu, Tien-Min G; Conley, Carolynn L; Chakraborty, Nabarun; Hammamieh, Rasha; Kacena, Melissa A

2018-02-01

Segmental bone defects (SBDs) secondary to trauma invariably result in a prolonged recovery with an extended period of limited weight bearing on the affected limb. Soldiers sustaining blast injuries and civilians sustaining high energy trauma typify such a clinical scenario. These patients frequently sustain composite injuries with SBDs in concert with extensive soft tissue damage. For soft tissue injury resolution and skeletal reconstruction a patient may experience limited weight bearing for upwards of 6 months. Many small animal investigations have evaluated interventions for SBDs. While providing foundational information regarding the treatment of bone defects, these models do not simulate limited weight bearing conditions after injury. For example, mice ambulate immediately following anesthetic recovery, and in most cases are normally ambulating within 1-3 days post-surgery. Thus, investigations that combine disuse with bone healing may better test novel bone healing strategies. To remove weight bearing, we have designed a SBD rodent healing study in microgravity (µG) on the International Space Station (ISS) for the Rodent Research-4 (RR-4) Mission, which launched February 19, 2017 on SpaceX CRS-10 (Commercial Resupply Services). In preparation for this mission, we conducted an end-to-end mission simulation consisting of surgical infliction of SBD followed by launch simulation and hindlimb unloading (HLU) studies. In brief, a 2 mm defect was created in the femur of 10 week-old C57BL6/J male mice (n = 9-10/group). Three days after surgery, 6 groups of mice were treated as follows: 1) Vivarium Control (maintained continuously in standard cages); 2) Launch Negative Control (placed in the same spaceflight-like hardware as the Launch Positive Control group but were not subjected to launch simulation conditions); 3) Launch Positive Control (placed in spaceflight-like hardware and also subjected to vibration followed by centrifugation); 4) Launch Positive Experimental (identical to Launch Positive Control group, but placed in qualified spaceflight hardware); 5) Hindlimb Unloaded (HLU, were subjected to HLU immediately after launch simulation tests to simulate unloading in spaceflight); and 6) HLU Control (single housed in identical HLU cages but not suspended). Mice were euthanized 28 days after launch simulation and bone healing was examined via micro-Computed Tomography (µCT). These studies demonstrated that the mice post-surgery can tolerate launch conditions. Additionally, forces and vibrations associated with launch did not impact bone healing (p = .3). However, HLU resulted in a 52.5% reduction in total callus volume compared to HLU Controls (p = .0003). Taken together, these findings suggest that mice having a femoral SBD surgery tolerated the vibration and hypergravity associated with launch, and that launch simulation itself did not impact bone healing, but that the prolonged lack of weight bearing associated with HLU did impair bone healing. Based on these findings, we proceeded with testing the efficacy of FDA approved and novel SBD therapies using the unique spaceflight environment as a novel unloading model on SpaceX CRS-10. Copyright © 2017 The Committee on Space Research (COSPAR). All rights reserved.

Toll-Like Receptor 2 Stimulation of Osteoblasts Mediates Staphylococcus Aureus Induced Bone Resorption and Osteoclastogenesis through Enhanced RANKL

PubMed Central

Kassem, Ali; Lindholm, Catharina; Lerner, Ulf H

2016-01-01

Severe Staphylococcus aureus (S. aureus) infections pose an immense threat to population health and constitute a great burden for the health care worldwide. Inter alia, S. aureus septic arthritis is a disease with high mortality and morbidity caused by destruction of the infected joints and systemic bone loss, osteoporosis. Toll-Like receptors (TLRs) are innate immune cell receptors recognizing a variety of microbial molecules and structures. S. aureus recognition via TLR2 initiates a signaling cascade resulting in production of various cytokines, but the mechanisms by which S. aureus causes rapid and excessive bone loss are still unclear. We, therefore, investigated how S. aureus regulates periosteal/endosteal osteoclast formation and bone resorption. S. aureus stimulation of neonatal mouse parietal bone induced ex vivo bone resorption and osteoclastic gene expression. This effect was associated with increased mRNA and protein expression of receptor activator of NF-kB ligand (RANKL) without significant change in osteoprotegerin (OPG) expression. Bone resorption induced by S. aureus was abolished by OPG. S. aureus increased the expression of osteoclastogenic cytokines and prostaglandins in the parietal bones but the stimulatory effect of S. aureus on bone resorption and Tnfsf11 mRNA expression was independent of these cytokines and prostaglandins. Stimulation of isolated periosteal osteoblasts with S. aureus also resulted in increased expression of Tnfsf11 mRNA, an effect lost in osteoblasts from Tlr2 knockout mice. S. aureus stimulated osteoclastogenesis in isolated periosteal cells without affecting RANKL-stimulated resorption. In contrast, S. aureus inhibited RANKL-induced osteoclast formation in bone marrow macrophages. These data show that S. aureus enhances bone resorption and periosteal osteoclast formation by increasing osteoblast RANKL production through TLR2. Our study indicates the importance of using different in vitro approaches for studies of how S. aureus regulates osteoclastogenesis to obtain better understanding of the complex mechanisms of S. aureus induced bone destruction in vivo. PMID:27311019

Using the Abitibi Greenstone Belt to Understand Martian Hydrothermal Systems and the Potential for Biosignature Preservation in High Temperature Aqueous Environments

NASA Technical Reports Server (NTRS)

Hurowitz, J.; Abelson, J.; Allwood, A.; Anderson, R.; Atkinson, B.; Beaty, D.; Bristow, T.; Ehlmann, B.; Eigenbrode, J.; Grotzinger, J.;

Evidence that Resorption of Bone by Rat Peritoneal Macrophages Occurs in an Acidic Environment

NASA Technical Reports Server (NTRS)

Blair, H. C.

1985-01-01

Skeletal loss in space, like any form of osteoporosis, reflects a relative imbalance of the activities of cells resorbing (degrading) or forming bone. Consequently, prevention of weightlessness induced bone loss may theoretically be accomplished by (1) stimulating bone formation or (2) inhibiting bone resorption. This approach, however, requires fundamental understanding of the mechanisms by which cells form or degrade bone, information not yet at hand. An issue central to bone resorption is the pH at which resorption takes place. The pH dependent spectral shift of a fluorescent dye (fluorescein isothiocyanate) conjugated to bone matrix was used to determine the pH at the resorptive cell bone matrix interface. Devitalized rat bone was used as the substrate, and rat peritoneal macrophages were used as the bone resorbing cells. The results suggest that bone resorption is the result of generation of an acidic microenvironment at the cell matrix junction.

Comparison of naturally occurring and ligature-induced peri-implantitis bone defects in humans and dogs.

PubMed

Schwarz, Frank; Herten, Monika; Sager, Martin; Bieling, Katrin; Sculean, Anton; Becker, Jürgen

2007-04-01

The aim of the present study was to evaluate and compare naturally occuring and ligature-induced peri-implantitis bone defects in humans and dogs. Twenty-four partially and fully edentulous patients undergoing peri-implant bone augmentation procedures due to advanced peri-implant infections were included in this study (n=40 implants). Furthermore, peri-implantitis was induced by ligature placement and plaque accumulation in five beagle dogs for three months following implant insertion (n=15 implants). The ligatures were removed when about 30% of the initial bone was lost. During open flap surgery, configuration and defect characteristics of the peri-implant bone loss were recorded in both humans and dogs. Open flap surgery generally revealed two different classes of peri-implant bone defects. While Class I defects featured well-defined intrabony components, Class II defects were characterized by consistent horizontal bone loss. The allocation of intrabony components of Class I defects regarding the implant body allowed a subdivision of five different configurations (Classes Ia-e). In particular, human defects were most frequently Class Ie (55.3%), followed by Ib (15.8%), Ic (13.3%), Id (10.2%), and Ia (5.4%). Similarly, bone defects in dogs were also most frequently Class Ie (86.6%), while merely two out of 15 defects were Classes Ia and Ic (6.7%, respectively). Within the limits of the present study, it might be concluded that configurations and sizes of ligature-induced peri-implantitis bone defects in dogs seemed to resemble naturally occurring lesions in humans.

Low Magnitude, High Frequency Signals Could Reduce Bone Loss During Spaceflight

NASA Astrophysics Data System (ADS)

Hawkey, A.

The removal of gravitational loading results in a loss of homeostasis of the skeleton. This leads to significant losses of bone mass during long-duration missions in space. Conventional exercise countermeasures, such as running and resistance training, have only limited effectiveness in reducing the rate at which bone is demineralised in microgravity. Bone loss, therefore, remains a major concern and if not annulled could be so severe as to jeopardise an extended human presence in space. In addition, current exercise regimes occupy valuable crew time, and astronauts often find the equipment cumbersome and uncomfortable to use. Recent studies suggest that exposing the body to short periods (<20mins) of low magnitude (<1g), high frequency (15-35Hz) signals (vibration) everyday could reduce, even prevent, bone loss during conditions such as osteoporo- sis on earth. The new vibration therapy treatment could also have several advantages over existing exercise countermeasures used in spaceflight due to it being very simple to operate, relatively inexpensive, and requiring only short periods of time `training', unlike the complicated, expensive and time-consuming devices currently used. This review highlights the detrimen- tal effects that microgravity has on the strength and integrity of bone, how current countermeasures are ineffective at stemming this level of deterioration, and how new vibration techniques could significantly reduce space-induced bone loss.

An overview of vertebrate mineralization with emphasis on collagen-mineral interaction

NASA Technical Reports Server (NTRS)

Landis, W. J.

1999-01-01

The nucleation, growth, and development of mineral crystals through their interaction principally with collagen in normal bone and calcifying tendon have been elaborated by applying a number of different techniques for analysis of the inorganic and organic constituents of these tissues. The methods have included conventional and high voltage electron microscopy, electron diffraction, microscopic tomography and 3D image reconstruction, and atomic force microscopy. This summary presents results of these studies that have now characterized the size, shape, and aspects of the chemical nature of the crystals as well as their orientation, alignment, location, and distribution with respect to collagen. These data have provided the means for understanding more completely the formation and strength of the collagen-mineral composite present in most vertebrate calcifying tissues and, from that information, a basis for the adaptation of such tissues under mechanical constraints. In the context of the latter point, other data are given showing effects on collagen in bone cell cultures subjected to the unloading parameters of spaceflight. Implications of these results may be particularly relevant to explaining loss of bone by humans and other vertebrate animals during missions in space, during situations of extended fracture healing, long-term bedrest, physical immobilization, and related conditions. In a broader sense, the data speak to the response of bone and mineralized vertebrate tissues to changes in gravitational loading and applied mechanical forces in general.

Markers of bone turnover in patients with epilepsy and their relationship to management of bone diseases induced by antiepileptic drugs.

PubMed

Hamed, Sherifa A

2016-01-01

Data from cross-sectional and prospective studies revealed that patients with epilepsy and on long-term treatment with antiepileptic drugs (AEDs) are at increased risk for metabolic bone diseases. Bone diseases were reported in about 50% of patients on AEDs. Low bone mineral density, osteopenia/osteoporosis, osteomalacia, rickets, altered concentration of bone turnover markers and fractures were reported with phenobarbital, phenytoin, carbamazepine, valproate, oxcarbazepine and lamotrigine. The mechanisms for AEDs-induced bone diseases are heterogeneous and include hypovitaminosis D, hypocalcemia and direct acceleration of bone loss and/or reduction of bone formation. This article reviews the evidence, predictors and mechanisms of AEDs-induced bone abnormalities and its clinical implications. For patients on AEDs, regular monitoring of bone health is recommended. Prophylactic administration of calcium and vitamin D is recommended for all patients. Treatment doses of calcium and vitamin D and even anti-resorptive drug therapy are reserved for patients at high risk of pathological fracture.

Effects of Spaceflight on Bone: The Rat as an Animal Model for Human Bone Loss

NASA Technical Reports Server (NTRS)

Halloran, B.; Weider, T.; Morey-Holton, E.

1999-01-01

The loss of weight bearing during spaceflight results in osteopenia in humans. Decrements in bone mineral reach 3-10% after as little as 75-184 days in space. Loss of bone mineral during flight decreases bone strength and increases fracture risk. The mechanisms responsible for, and the factors contributing to, the changes in bone induced by spaceflight are poorly understood. The rat has been widely used as an animal model for human bone loss during spaceflight. Despite its potential usefulness, the results of bone studies performed in the rat in space have been inconsistent. In some flights bone formation is decreased and cancellous bone volume reduced, while in others no significant changes in bone occur. In June of 1996 Drs. T. Wronski, S. Miller and myself participated in a flight experiment (STS 78) to examine the effects of glucocorticoids on bone during weightlessness. Technically the 17 day flight experiment was flawless. The results, however, were surprising. Cancellous bone volume and osteoblast surface in the proximal tibial metaphysis were the same in flight and ground-based control rats. Normal levels of cancellous bone mass and bone formation were also detected in the lumbar vertebrae and femoral neck of flight rats. Furthermore, periosteal bone formation rate was found to be identical in flight and ground-based control rats. Spaceflight had little or no effect on bone metabolism! These results prompted us to carefully review the changes in bone observed in, and the flight conditions of previous spaceflight missions.

Theophylline, a methylxanthine drug induces osteopenia and alters calciotropic hormones, and prophylactic vitamin D treatment protects against these changes in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pal, Subhashis; Khan, Kainat; China, Shyamsundar Pal

The drug, theophylline is frequently used as an additive to medications for people suffering from chronic obstructive pulmonary diseases (COPD). We studied the effect of theophylline in bone cells, skeleton and parameters related to systemic calcium homeostasis. Theophylline induced osteoblast apoptosis by increasing reactive oxygen species production that was caused by increased cAMP production. Bone marrow levels of theophylline were higher than its serum levels, indicating skeletal accumulation of this drug. When adult Sprague-Dawley rats were treated with theophylline, bone regeneration at fracture site was diminished compared with control. Theophylline treatment resulted in a time-dependent (at 4- and 8 weeks)more » bone loss. At 8 weeks, a significant loss of bone mass and deterioration of microarchitecture occurred and the severity was comparable to methylprednisone. Theophylline caused formation of hypomineralized osteoid and increased osteoclast number and surface. Serum bone resorption and formation marker were respectively higher and lower in the theophylline group compared with control. Bone strength was reduced by theophylline treatment. After 8 weeks, serum 25-D3 and liver 25-hydroxylases were decreased in theophylline group than control. Further, theophylline treatment reduced serum 1, 25-(OH){sub 2} vitamin D{sub 3} (1,25-D3), and increased parathyroid hormone and fibroblast growth factor-23. Theophylline treated rats had normal serum calcium and phosphate but displayed calciuria and phosphaturia. Co-administration of 25-D3 with theophylline completely abrogated theophylline-induced osteopenia and alterations in calcium homeostasis. In addition, 1,25-D3 protected osteoblasts from theophylline-induced apoptosis and the attendant oxidative stress. We conclude that theophylline has detrimental effects in bone and prophylactic vitamin D supplementation to subjects taking theophylline could be osteoprotective. - Highlights: • Theophylline induced osteoblast apoptosis by cAMP-induced ROS generation. • Theophylline levels in bone marrow were much higher than blood. • Theophylline diminished bone regeneration at the fracture site and caused osteopenia. • Theophylline caused hypo-vitaminosis D, and altered calciotropic hormones. • Vitamin D treatment prevented theophylline-induced changes in bone metabolism.« less

A role for subchondral bone changes in the process of osteoarthritis; a micro-CT study of two canine models.

PubMed

Sniekers, Yvonne H; Intema, Femke; Lafeber, Floris P J G; van Osch, Gerjo J V M; van Leeuwen, Johannes P T M; Weinans, Harrie; Mastbergen, Simon C

2008-02-12

This study evaluates changes in peri-articular bone in two canine models for osteoarthritis: the groove model and the anterior cruciate ligament transection (ACLT) model. Evaluation was performed at 10 and 20 weeks post-surgery and in addition a 3-weeks time point was studied for the groove model. Cartilage was analysed, and architecture of the subchondral plate and trabecular bone of epiphyses was quantified using micro-CT. At 10 and 20 weeks cartilage histology and biochemistry demonstrated characteristic features of osteoarthritis in both models (very mild changes at 3 weeks). The groove model presented osteophytes only at 20 weeks, whereas the ACLT model showed osteophytes already at 10 weeks. Trabecular bone changes in the groove model were small and not consistent. This contrasts the ACLT model in which bone volume fraction was clearly reduced at 10 and 20 weeks (15-20%). However, changes in metaphyseal bone indicate unloading in the ACLT model, not in the groove model. For both models the subchondral plate thickness was strongly reduced (25-40%) and plate porosity was strongly increased (25-85%) at all time points studied. These findings show differential regulation of subchondral trabecular bone in the groove and ACLT model, with mild changes in the groove model and more severe changes in the ACLT model. In the ACLT model, part of these changes may be explained by unloading of the treated leg. In contrast, subchondral plate thinning and increased porosity were very consistent in both models, independent of loading conditions, indicating that this thinning is an early response in the osteoarthritis process.

Maintaining Restored Bone with Bisphoshonate in the Ovariectomized Rat Skeleton: Dynamic Histomorphometry of Changes in Bone Mass

NASA Technical Reports Server (NTRS)

Jee, W. S. S.; Tang, L.; Ke, H. Z.; Setterberg, R. B.; Kimmel, D. B.

1993-01-01

This experiment contains the crucial data for the Lose, Restore and Maintain (LRM) concept, a practical approach for reversing existing osteoporosis. The LRM concept uses ovariectomy (ox) to lose bone, an anabolic agent to restore bone mass and then switches to an anti-resorptive agent to maintain bone mass. We ox'd or sham-ox'd rats for 150 days (Loss Phase), treated them with 6 mg PGE2/kg/d for 75 days to restore lost cancellous bone mass (Restore Phase) and then stopped PGE2 treatment and began treatment with 1 or 5 micro-g/kg Risedronate, a bisphosphonate twice a week for 60 days (Maintain Phase). During the Loss Phase, cancellous bone volumes of the proximal tibial metaphysis (PTM) in the ox'd rat fell to 19% of initial controls. During the Restore Phase, the PTM bone volume in ox'd rats doubled. However, when PGE2 treatment was stopped, the PGE2-induced cancellous bone disappeared. In contrast, 5 micro-g of Risedronate inhibited the bone loss and maintained it at the PGE2 treatment level. The key dynamic histomorphometry value for the restore (R) and maintenance (M) phases was the ratio of bone formation to resorption rates. The ratio was elevated to 5.8 in the R phase and depressed to 0.4 for no and 1 micro-g Risedronate treated M phase and to a ratio of near unity of 1.1 for the 5 micro-g Risedronate treatment. These findings indicate that we were successful in maintaining the new PTM bone induced by PGE2 after discontinuing PGE2 by administering enough Risedronate, a resorption inhibitor. We concluded that the LRM concept is correct and such an approach should be considered when employing anabolic agents or growth factors in the treatment of osteoporosis. Continued use of an anabolic agent may not be appropriate because of cost, potential adverse side effects and a loss of efficacy.

Maintaining Restored Bone with Bisphosphonate in the Ovariectomized Rat Skeleton: Dynamic Histomorphometry of Changes in Bone Mass

NASA Technical Reports Server (NTRS)

Jee, W. S. S.; Tang, L.; Ke, H. Z.; Setterberg, R. B.; Kimmel, D. B.

1993-01-01

This experiment contains the crucial data for the Lose, Restore and Maintain (LRM) concept, a practical approach for reversing existing osteoporosis. The LRM concept uses ovariectomy (ox) to lose bone, an anabolic agent to restore bone mass and then switches to an antiresorptive agent to maintain bone mass. We ox'd or sham-ox'd rats for 150 days (Loss Phase), treated them with 6 mg PGE(sub 2)kg/d for 75 days to restore lost cancellous bone mass (Restore Phase) and then stopped PGE(sub 2) treatment and began treatment with 1 or 5 micrograms/kg Risedronate, a bisphosphonate twice a week for 60 days (Maintain Phase). During the Loss Phase, cancellous bone volumes of the Proximal Tibial Metaphysis (PTM) in the ox'd rat fell to 19% of initial controls. During the Restore Phase, the PTM bone volume in ox'd rats doubled. However, when PGE(sub 2) treatment was stopped, the PGE(sub 2)-induced cancellous bone disappeared. In contrast, 5 miligrams of Risedronate inhibited the bone loss and maintained it at the PGE(sub 2) treatment level. The key dynamic histomorphometry value for the Restore (R) and Maintenance (M) phases was the ratio of bone formation to resorption rates. The ratio was elevated to 5.8 in the R phase and depressed to 0.4 for no and 1 miligram Risedronate treated M phase and to a ratio of near unity of 1.1 for the 5miligrams Risedronate treatment. These findings indicate that we were successful in maintaining the new PTM bone induced by PGE(sub 2) after discontinuing PGE(sub 2) by administering enough Risedronate, a resorption inhibitor. We concluded that the LRM concept is correct and such an approach should be considered when employing anabolic agents or growth factors in the treatment of osteoporosis. Continued use of an anabolic agent may not be appropriate because of cost, potential adverse side effects and a loss of efficacy.

Early consumption of blueberry diet protects against sex steroid deficiency-induced bone loss in adult female rats

USDA-ARS?s Scientific Manuscript database

We studied the effects of blueberry consumption in early development on bone loss in ovariectomized (OVX) female rats later in life. Weanling female rats were fed AIN-93G semi-purified diets supplemented with 10% whole blueberry powder from PND 21 to PND34 (short-term group), or PND21 to PND81 (chro...

Local delivery of parathyroid hormone-related protein-derived peptides coated onto a hydroxyapatite-based implant enhances bone regeneration in old and diabetic rats.

PubMed

Ardura, Juan A; Portal-Núñez, Sergio; Lozano, Daniel; Gutiérrez-Rojas, Irene; Sánchez-Salcedo, Sandra; López-Herradón, Ana; Mulero, Francisca; Villanueva-Peñacarrillo, María L; Vallet-Regí, María; Esbrit, Pedro

2016-08-01

Diabetes mellitus (DM) and aging are associated with bone fragility and increased fracture risk. Both (1-37) N- and (107-111) C-terminal parathyroid hormone-related protein (PTHrP) exhibit osteogenic properties. We here aimed to evaluate and compare the efficacy of either PTHrP (1-37) or PTHrP (107-111) loaded into gelatin-glutaraldehyde-coated hydroxyapatite (HA-Gel) foams to improve bone repair of a transcortical tibial defect in aging rats with or without DM, induced by streptozotocin injection at birth. Diabetic old rats showed bone structural deterioration compared to their age-matched controls. Histological and μ-computerized tomography studies showed incomplete bone repair at 4 weeks after implantation of unloaded Ha-Gel foams in the transcortical tibial defects, mainly in old rats with DM. However, enhanced defect healing, as shown by an increase of bone volume/tissue volume and trabecular and cortical thickness and decreased trabecular separation, occurred in the presence of either PTHrP peptide in the implants in old rats with or without DM. This was accompanied by newly formed bone tissue around the osteointegrated HA-Gel implant and increased gene expression of osteocalcin and vascular endothelial growth factor (bone formation and angiogenic markers, respectively), and decreased expression of Sost gene, a negative regulator of bone formation, in the healing bone area. Our findings suggest that local delivery of PTHrP (1-37) or PTHrP (107-111) from a degradable implant is an attractive strategy to improve bone regeneration in aged and diabetic subjects. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2060-2070, 2016. © 2016 Wiley Periodicals, Inc.

Early loss of subchondral bone following microfracture is counteracted by bone marrow aspirate in a translational model of osteochondral repair

PubMed Central

Gao, Liang; Orth, Patrick; Müller-Brandt, Kathrin; Goebel, Lars K. H.; Cucchiarini, Magali; Madry, Henning

2017-01-01

Microfracture of cartilage defects may induce alterations of the subchondral bone in the mid- and long-term, yet very little is known about their onset. Possibly, these changes may be avoided by an enhanced microfracture technique with additional application of bone marrow aspirate. In this study, full-thickness chondral defects in the knee joints of minipigs were either treated with (1) debridement down to the subchondral bone plate alone, (2) debridement with microfracture, or (3) microfracture with additional application of bone marrow aspirate. At 4 weeks after microfracture, the loss of subchondral bone below the defects largely exceeded the original microfracture holes. Of note, a significant increase of osteoclast density was identified in defects treated with microfracture alone compared with debridement only. Both changes were significantly counteracted by the adjunct treatment with bone marrow. Debridement and microfracture without or with bone marrow were equivalent regarding the early cartilage repair. These data suggest that microfracture induced a substantial early resorption of the subchondral bone and also highlight the potential value of bone marrow aspirate as an adjunct to counteract these alterations. Clinical studies are warranted to further elucidate early events of osteochondral repair and the effect of enhanced microfracture techniques. PMID:28345610

Dietary emu oil supplementation suppresses 5-fluorouracil chemotherapy-induced inflammation, osteoclast formation, and bone loss.

PubMed

Raghu Nadhanan, Rethi; Abimosleh, Suzanne M; Su, Yu-Wen; Scherer, Michaela A; Howarth, Gordon S; Xian, Cory J

2012-06-01

Cancer chemotherapy can cause osteopenia or osteoporosis, and yet the underlying mechanisms remain unclear, and currently, no preventative treatments are available. This study investigated damaging effects of 5-fluorouracil (5-FU) on histological, cellular, and molecular changes in the tibial metaphysis and potential protective benefits of emu oil (EO), which is known to possess a potent anti-inflammatory property. Female dark agouti rats were gavaged orally with EO or water (1 ml·day(-1)·rat(-1)) for 1 wk before a single ip injection of 5-FU (150 mg/kg) or saline (Sal) was given. The treatment groups were H(2)O + Sal, H(2)O + 5-FU, EO + 5-FU, and EO + Sal. Oral gavage was given throughout the whole period up to 1 day before euthanasia (days 3, 4, and 5 post-5-FU). Histological analysis showed that H(2)O + 5-FU significantly reduced heights of primary spongiosa on days 3 and 5 and trabecular bone volume of secondary spongiosa on days 3 and 4. It reduced density of osteoblasts slightly and caused an increase in the density of osteoclasts on trabecular bone surface on day 4. EO supplementation prevented reduction of osteoblasts and induction of osteoclasts and bone loss caused by 5-FU. Gene expression studies confirmed an inhibitory effect of EO on osteoclasts since it suppressed 5-FU-induced expression of proinflammatory and osteoclastogenic cytokine TNFα, osteoclast marker receptor activator of nuclear factor-κB, and osteoclast-associated receptor. Therefore, this study demonstrated that EO can counter 5-FU chemotherapy-induced inflammation in bone, preserve osteoblasts, suppress osteoclast formation, and potentially be useful in preventing 5-FU chemotherapy-induced bone loss.

Dietary coral calcium and zeolite protects bone in a mouse model for postmenopausal bone loss.

PubMed

Banu, Jameela; Varela, Erika; Guerra, Juan M; Halade, Ganesh; Williams, Paul J; Bahadur, Ali N; Hanaoka, Kokichi; Fernandes, Gabriel

2012-12-01

In patients diagnosed with osteoporosis, calcium is lost from bones making them weaker and easily susceptible to fractures. Supplementation of calcium is highly recommended for such conditions. However, the source of calcium plays an important role in the amount of calcium that is assimilated into bone. We hypothesize that naturally occurring coral calcium and zeolite may prevent ovariectomy-induced bone loss. We have measured bone loss in ovariectomized mice supplemented with coral calcium and Zeolite. Female C57BL/6 mice were either sham-operated or ovariectomized and fed diets containing coral calcium or zeolite for 6 months. Serum was analyzed for bone biochemical markers and cytokines. Bones were analyzed using dual x-ray absorbtiometry, peripheral quantitative computed tomography, and micro-computed tomography densitometry. In the distal femoral metaphysis, total bone and cortical bone mass was restored and the endocortical surface was significantly decreased in coral calcium and zeolite fed ovariectomized (OVX) mice. Trabecular number and the ratio of bone volume to total volume was higher in OVX mice after coral calcium and zeolite feeding, while trabecular separation decreased in the different treatment OVX groups. Coral calcium protected bone to a lesser extent in the proximal tibia and lumbar vertebrae. Overall, coral calcium and zeolite may protect postmenopausal bone loss. Copyright © 2012 Elsevier Inc. All rights reserved.

Hindlimb unloading alters ligament healing

NASA Technical Reports Server (NTRS)

Provenzano, Paolo P.; Martinez, Daniel A.; Grindeland, Richard E.; Dwyer, Kelley W.; Turner, Joanne; Vailas, Arthur C.; Vanderby, Ray Jr

2003-01-01

We investigated the hypothesis that hindlimb unloading inhibits healing in fibrous connective tissue such as ligament. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing, and hindlimb-suspended healing. Ambulatory and suspended animals underwent surgical rupture of their medial collateral ligaments, whereas sham surgeries were performed on control animals. After 3 or 7 wk, mechanical and/or morphological properties were measured in ligament, muscle, and bone. During mechanical testing, most suspended ligaments failed in the scar region, indicating the greatest impairment was to ligament and not to bone-ligament insertion. Ligament testing revealed significant reductions in maximum force, ultimate stress, elastic modulus, and low-load properties in suspended animals. In addition, femoral mineral density, femoral strength, gastrocnemius mass, and tibialis anterior mass were significantly reduced. Microscopy revealed abnormal scar formation and cell distribution in suspended ligaments with extracellular matrix discontinuities and voids between misaligned, but well-formed, collagen fiber bundles. Hence, stress levels from ambulation appear unnecessary for formation of fiber bundles yet required for collagen to form structurally competent continuous fibers. Results support our hypothesis that hindlimb unloading impairs healing of fibrous connective tissue. In addition, this study provides compelling morphological evidence explaining the altered structure-function relationship in load-deprived healing connective tissue.

Expression of a calpastatin transgene slows muscle wasting and obviates changes in myosin isoform expression during murine muscle disuse

NASA Technical Reports Server (NTRS)

Tidball, James G.; Spencer, Melissa J.

2002-01-01

Muscle wasting is a prominent feature of several systemic diseases, neurological damage and muscle disuse. The contribution of calpain proteases to muscle wasting in any instance of muscle injury or disease has remained unknown because of the inability to specifically perturb calpain activity in vivo. We have generated a transgenic mouse with muscle-specific overexpression of calpastatin, which is the endogenous inhibitor of calpains, and induced muscle atrophy by unloading hindlimb musculature for 10 days. Expression of the transgene resulted in increases in calpastatin concentration in muscle by 30- to 50-fold, and eliminated all calpain activity that was detectable on zymograms. Muscle fibres in ambulatory, transgenic mice were smaller in diameter, but more numerous, so that muscle mass did not differ between transgenic and non-transgenic mice. This is consistent with the role of the calpain-calpastatin system in muscle cell fusion that has been observed in vitro. Overexpression of calpastatin reduced muscle atrophy by 30 % during the 10 day unloading period. In addition, calpastatin overexpression completely prevented the shift in myofibrillar myosin content from slow to fast isoforms, which normally occurs in muscle unloading. These findings indicate that therapeutics directed toward regulating the calpain-calpastatin system may be beneficial in preventing muscle mass loss in muscle injury and disease.

Expression of a calpastatin transgene slows muscle wasting and obviates changes in myosin isoform expression during murine muscle disuse.

PubMed

Tidball, James G; Spencer, Melissa J

2002-12-15

Muscle wasting is a prominent feature of several systemic diseases, neurological damage and muscle disuse. The contribution of calpain proteases to muscle wasting in any instance of muscle injury or disease has remained unknown because of the inability to specifically perturb calpain activity in vivo. We have generated a transgenic mouse with muscle-specific overexpression of calpastatin, which is the endogenous inhibitor of calpains, and induced muscle atrophy by unloading hindlimb musculature for 10 days. Expression of the transgene resulted in increases in calpastatin concentration in muscle by 30- to 50-fold, and eliminated all calpain activity that was detectable on zymograms. Muscle fibres in ambulatory, transgenic mice were smaller in diameter, but more numerous, so that muscle mass did not differ between transgenic and non-transgenic mice. This is consistent with the role of the calpain-calpastatin system in muscle cell fusion that has been observed in vitro. Overexpression of calpastatin reduced muscle atrophy by 30 % during the 10 day unloading period. In addition, calpastatin overexpression completely prevented the shift in myofibrillar myosin content from slow to fast isoforms, which normally occurs in muscle unloading. These findings indicate that therapeutics directed toward regulating the calpain-calpastatin system may be beneficial in preventing muscle mass loss in muscle injury and disease.

Mice Drawer System

NASA Technical Reports Server (NTRS)

Cancedda, Ranieri

2008-01-01

The Mice Drawer System (MDS) is an Italian Space Agency (ASI) facility which is able to support mice onboard the International Space Station during long-duration exploration missions (from 100 to 150-days) by living space, food, water, ventilation and lighting. Mice can be accommodated either individually (maximum 6) or in groups (4 pairs). MDS is integrated in the Space Shuttle middeck during transportation (uploading and downloading) to the ISS and in an EXPRESS Rack in Destiny, the US Laboratory during experiment execution. Osteoporosis is a debilitating disease that afflicts millions of people worldwide. One of the physiological changes experienced by astronauts during space flight is the accelerated loss of bone mass due to the lack of gravitational loading on the skeleton. This bone loss experienced by astronauts is similar to osteoporosis in the elderly population. MDS will help investigate the effects of unloading on transgenic (foreign gene that has been inserted into its genome to exhibit a particular trait) mice with the Osteoblast Stimulating Factor-1, OSF-1, a growth and differentiation factor, and to study the genetic mechanisms underlying the bone mass pathophysiology. MDS will test the hypothesis that mice with an increased bone density are likely to be more protected from osteoporosis, when the increased bone mass is a direct effect of a gene involved in skeletogenesis (skeleton formation). Osteoporosis is a debilitating disease that afflicts millions worldwide. One of the physiological changes experienced by astronauts during space flight is the accelerated loss of bone mass due to the lack of gravitational loading on the skeleton, a loss that is similar to osteoporosis in the elderly population on Earth. Osteoblast Stimulating Factor-1 (OSF-1), also known as pleiotrophin (PTN) or Heparin-Binding Growth- Associated Molecule (HB-GAM) belongs to a family of secreted heparin binding proteins..OSF-1 is an extracellular matrix-associated growth and differentiation factor that is normally expressed in cartilage; it can stimulate the proliferation and differentiation of human osteoprogenitor cells (cell that differentiate into an osteoblast) in vitro. The Mice Drawer System will study the effects of microgravity on transgenic mouse bones in order to identify genetic mechanisms playing a role in the reduction of the bone mass observed in humans and animals as a consequence of long-duration (greater than 100 days) microgravity exposure. Onboard the ISS, MDS is relatively self-sufficient; a crewmember will check the health status of the rodents on a daily basis, by assessing them through the viewing window. Water levels will be assessed by the crew daily and refilled as needed. Replacement of the food bars and replacement of the waste filters will be conducted inflight by crewmembers every 20-days.

Evaluation of muscle activity for loaded and unloaded dynamic squats during vertical whole-body vibration.

PubMed

Hazell, Tom J; Kenno, Kenji A; Jakobi, Jennifer M

2010-07-01

The purpose of this investigation was to examine if the addition of a light external load would enhance whole-body vibration (WBV)-induced increases in muscle activity during dynamic squatting in 4 leg muscles. Thirteen recreationally active male university students performed a series of dynamic squats (unloaded with no WBV, unloaded with WBV, loaded with no WBV, and loaded with WBV). The load was set to 30% of body mass and WBV included 25-, 35-, and 45-Hz frequencies with 4-mm amplitude. Muscle activity was recorded with surface electromyography (EMG) on the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GC) and is reported as EMGrms (root mean square) normalized to %maximal voluntary exertion. During unloaded dynamic squats, exposure to WBV (45 Hz) significantly (p < 0.05) increased baseline muscle activity in all muscles, except the TA compared with no WBV. Adding a light external load without WBV increased baseline muscle activity of the squat exercise in all muscles but decreased the TA. This loaded level of muscle activity was further increased with WBV (45 Hz) in all muscles. The WBV-induced increases in muscle activity in the loaded condition (approximately 3.5%) were of a similar magnitude to the WBV-induced increases during the unloaded condition (approximately 2.5%) demonstrating the addition of WBV to unloaded or loaded dynamic squatting results in an increase in muscle activity. These results demonstrate the potential effectiveness of using external loads with exposure to WBV.

Impaired translocation of GLUT4 results in insulin resistance of atrophic soleus muscle.

PubMed

Xu, Peng-Tao; Song, Zhen; Zhang, Wen-Cheng; Jiao, Bo; Yu, Zhi-Bin

2015-01-01

Whether or not the atrophic skeletal muscle induces insulin resistance and its mechanisms are not resolved now. The antigravity soleus muscle showed a progressive atrophy in 1-week, 2-week, and 4-week tail-suspended rats. Hyperinsulinemic-euglycemic clamp showed that the steady-state glucose infusion rate was lower in 4-week tail-suspended rats than that in the control rats. The glucose uptake rates under insulin- or contraction-stimulation were significantly decreased in 4-week unloaded soleus muscle. The key protein expressions of IRS-1, PI3K, and Akt on the insulin-dependent pathway and of AMPK, ERK, and p38 on the insulin-independent pathway were unchanged in unloaded soleus muscle. The unchanged phosphorylation of Akt and p38 suggested that the activity of two signal pathways was not altered in unloaded soleus muscle. The AS160 and GLUT4 expression on the common downstream pathway also was not changed in unloaded soleus muscle. But the GLUT4 translocation to sarcolemma was inhibited during insulin stimulation in unloaded soleus muscle. The above results suggest that hindlimb unloading in tail-suspended rat induces atrophy in antigravity soleus muscle. The impaired GLUT4 translocation to sarcolemma under insulin stimulation may mediate insulin resistance in unloaded soleus muscle and further affect the insulin sensitivity of whole body in tail-suspended rats.

Impaired Translocation of GLUT4 Results in Insulin Resistance of Atrophic Soleus Muscle

PubMed Central

Xu, Peng-Tao; Song, Zhen; Zhang, Wen-Cheng; Jiao, Bo; Yu, Zhi-Bin

2015-01-01

Whether or not the atrophic skeletal muscle induces insulin resistance and its mechanisms are not resolved now. The antigravity soleus muscle showed a progressive atrophy in 1-week, 2-week, and 4-week tail-suspended rats. Hyperinsulinemic-euglycemic clamp showed that the steady-state glucose infusion rate was lower in 4-week tail-suspended rats than that in the control rats. The glucose uptake rates under insulin- or contraction-stimulation were significantly decreased in 4-week unloaded soleus muscle. The key protein expressions of IRS-1, PI3K, and Akt on the insulin-dependent pathway and of AMPK, ERK, and p38 on the insulin-independent pathway were unchanged in unloaded soleus muscle. The unchanged phosphorylation of Akt and p38 suggested that the activity of two signal pathways was not altered in unloaded soleus muscle. The AS160 and GLUT4 expression on the common downstream pathway also was not changed in unloaded soleus muscle. But the GLUT4 translocation to sarcolemma was inhibited during insulin stimulation in unloaded soleus muscle. The above results suggest that hindlimb unloading in tail-suspended rat induces atrophy in antigravity soleus muscle. The impaired GLUT4 translocation to sarcolemma under insulin stimulation may mediate insulin resistance in unloaded soleus muscle and further affect the insulin sensitivity of whole body in tail-suspended rats. PMID:25713812

Morphometric and histopathological evaluation of the effect of grape seed proanthocyanidin on alveolar bone loss in experimental diabetes and periodontitis.

PubMed

Toker, H; Balci Yuce, H; Lektemur Alpan, A; Gevrek, F; Elmastas, M

2018-06-01

Grape seed proanthocyanidine extract (GSPE) is a strong antioxidant derived from the grape seeds (Vitis vinifera, Terral J.F.) and has a polyphenolic structure with a wide range of biological activity. The aim of the present study was to evaluate the effects of GSPE on alveolar bone loss and histopathological changes in rats with diabetes mellitus and ligature-induced periodontitis. Forty rats were divided into 6 study groups. Control (C, 6 rats) group, periodontitis (P, 6 rats) group, diabetes (D, 6 rats) group, diabetes and periodontitis (D+P, 6 rats) group, diabetes, periodontitis and 100 mg/kg/day GSPE (GSPE-100, 8 rats), and diabetes, periodontitis and 200 mg/kg/day GSPE (GSPE-200, 8 rats) group. Diabetes mellitus was induced by intraperitoneal injection of a single dose of streptozotocin (60 mg/kg). Periodontitis was induced via ligation method. Silk ligatures were placed at the mandibular right first molars. GSPE was administered by oral gavage. After 30 days, all rats were killed. Alveolar bone loss was measured morphometrically via a stereomicroscope. For histopathological analyses, Alizarin red staining, and matrix metalloproteinase (MMP)-8, vascular endothelial growth factor and hypoxia inducible factor (HIF)-1α immunohistochemistry were performed. Tartrate-resistant acid phosphatase-positive osteoclast cells and relative total inflammatory cells were also determined. The highest alveolar bone loss was observed in the D+P group (P < .05). GSP-200 group decreased alveolar bone loss (P < .05). The D+P group had the highest osteoclast counts, but the difference was not significant compared to the P, GSPE-100 and GSPE-200 groups (P > .05). The inflammation in the D+P group was also higher than the other groups (P < .05). The osteoblast numbers increased in the GSPE-100 and GSPE-200 groups compared to the P and D+P groups (P < .05). MMP-8 and HIF-1α levels were highest in the D+P group and GSPE significantly decreased these levels (P < .05). Within the limits of this animal study, it can be suggested that GSPE administration may decrease periodontal inflammation and alveolar bone loss via decreasing MMP-8 and HIF-1α levels and increase osteoblastic activity in diabetic rats with experimental periodontitis. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cardiomyocyte Ca2+ handling and structure is regulated by degree and duration of mechanical load variation.

PubMed

Ibrahim, Michael; Kukadia, Punam; Siedlecka, Urszula; Cartledge, James E; Navaratnarajah, Manoraj; Tokar, Sergiy; Van Doorn, Carin; Tsang, Victor T; Gorelik, Julia; Yacoub, Magdi H; Terracciano, Cesare M

2012-12-01

Cardiac transverse (t)-tubules are altered during disease and may be regulated by stretch-sensitive molecules. The relationship between variations in the degree and duration of load and t-tubule structure remains unknown, as well as its implications for local Ca(2+)-induced Ca(2+) release (CICR). Rat hearts were studied after 4 or 8 weeks of moderate mechanical unloading [using heterotopic abdominal heart-lung transplantation (HAHLT)] and 6 or 10 weeks of pressure overloading using thoracic aortic constriction. CICR, cell and t-tubule structure were assessed using confocal-microscopy, patch-clamping and scanning ion conductance microscopy. Moderate unloading was compared with severe unloading [using heart-only transplantation (HAHT)]. Mechanical unloading reduced cardiomyocyte volume in a time-dependent manner. Ca(2+) release synchronicity was reduced at 8 weeks moderate unloading only. Ca(2+) sparks increased in frequency and duration at 8 weeks of moderate unloading, which also induced t-tubule disorganization. Overloading increased cardiomyocyte volume and disrupted t-tubule morphology at 10 weeks but not 6 weeks. Moderate mechanical unloading for 4 weeks had milder effects compared with severe mechanical unloading (37% reduction in cell volume at 4 weeks compared to 56% reduction after severe mechanical unloading) and did not cause depression and delay of the Ca(2+) transient, increased Ca(2+) spark frequency or impaired t-tubule and cell surface structure. These data suggest that variations in chronic mechanical load influence local CICR and t-tubule structure in a time- and degree-dependent manner, and that physiological states of increased and reduced cell size, without pathological changes are possible. © 2012 The Authors Journal of Cellular and Molecular Medicine © 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

Muscle sarcomere lesions and thrombosis after spaceflight and suspension unloading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, D.A.; Ellis, S.; Giometti, C.S.

1992-08-01

Extended exposure of humans to spaceflight produces a progressive loss of skeletal muscle strength. This process must be understood to design effective countermeasures. The present investigation examined hindlimb muscles from flight rats killed as close to landing as possible. Spaceflight and tail suspension-hindlimb unloading (unloaded) produced significant decreases in fiber cross-sectional areas of the adductor longus (AL), a slow-twitch antigravity muscle. However, the mean wet weight of the flight AL muscles was near normal, whereas that of the suspension unloaded AL muscles was significantly reduced. Interstitial edema within the flight AL, but not in the unloaded AL, appeared to accountmore » for this apparent disagreement.In both conditions, the slow-twitch oxidative fibers atrophied more than the fast-twitch oxidative-glycolytic fibers. Microcirculation was also compromised by spaceflight, such that there was increased formation of thrombi in the postcapillary venules and capillaries.« less

Immunization with FSHβ fusion protein antigen prevents bone loss in a rat ovariectomy-induced osteoporosis model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, Wenxin; Yan, Xingrong; Du, Huicong

Highlights: •A GST-FSH fusion protein was successfully expressed in E. coli. •Immunization with GST-FSH antigen can raise high-titer anti-FSH polyclonal sera. •Anti-FSH polyclonal sera can neutralize osteoclastogenic effect of FSH in vitro. •FSH immunization can prevent bone loss in a rat osteoporosis model. -- Abstract: Osteoporosis, a metabolic bone disease, threatens postmenopausal women globally. Hormone replacement therapy (HTR), especially estrogen replacement therapy (ERT), is used widely in the clinic because it has been generally accepted that postmenopausal osteoporosis is caused by estrogen deficiency. However, hypogonadal α and β estrogen receptor null mice were only mildly osteopenic, and mice with eithermore » receptor deleted had normal bone mass, indicating that estrogen may not be the only mediator that induces osteoporosis. Recently, follicle-stimulating hormone (FSH), the serum concentration of which increases from the very beginning of menopause, has been found to play a key role in postmenopausal osteoporosis by promoting osteoclastogenesis. In this article, we confirmed that exogenous FSH can enhance osteoclast differentiation in vitro and that this effect can be neutralized by either an anti-FSH monoclonal antibody or anti-FSH polyclonal sera raised by immunizing animals with a recombinant GST-FSHβ fusion protein antigen. Moreover, immunizing ovariectomized rats with the GST-FSHβ antigen does significantly prevent trabecular bone loss and thereby enhance the bone strength, indicating that a FSH-based vaccine may be a promising therapeutic strategy to slow down bone loss in postmenopausal women.« less

Prophylactic pamidronate partially protects from glucocorticoid-induced bone loss in the mdx mouse model of Duchenne muscular dystrophy.

PubMed

Yoon, Sung-Hee; Chen, Jinghan; Grynpas, Marc D; Mitchell, Jane

2016-09-01

Glucocorticoids are extensively used to treat patients with Duchenne muscular dystrophy because of their ability to delay muscle damage, prolong ambulation and extend life. However, use of glucocorticoids significantly increases bone loss, fragility and fractures. To determine if antiresorptive bisphosphonates could prevent the effects of glucocorticoids on bone quality, we used dystrophic mdx mice treated with the glucocorticoid prednisone during 8weeks of rapid bone growth from 5 to 13weeks of age and treated some mice with the bisphosphonate pamidronate during the first two weeks of prednisone administration. Prednisone reduced long bone growth, decreased cortical bone thickness and area and decreased the strength of the femurs. Pamidronate treatment protected mice from cortical bone loss but did not increase bone strength. The combination of prednisone and pamidronate inhibited remodeling of metaphyseal trabecular bone with large numbers of trabeculae containing remnants of calcified cartilage. Prednisone improved muscle strength in the mdx mice and decreased serum creatine kinase with evidence of improved muscle histology and these effects were maintained in mice treated with pamidronate. Copyright © 2016. Published by Elsevier Inc.

The orally available Btk inhibitor ibrutinib (PCI-32765) protects against osteoclast-mediated bone loss.

PubMed

Shinohara, Masahiro; Chang, Betty Y; Buggy, Joseph J; Nagai, Yusuke; Kodama, Tatsuhiko; Asahara, Hiroshi; Takayanagi, Hiroshi

2014-03-01

Bone-resorbing osteoclasts play an essential role in normal bone homeostasis, as well as in various bone disorders such as osteoporosis and rheumatoid arthritis. Previously we showed that the Tec family of tyrosine kinases is essential for the differentiation of osteoclasts and the inhibition of Btk is a promising strategy for the prevention of the bone loss in osteoclast-associated bone disorders. Here we demonstrate that an orally available Btk inhibitor, ibrutinib (PCI-32765), suppresses osteoclastic bone resorption by inhibiting both osteoclast differentiation and function. Ibrutinib downregulated the expression of NFATc1, the key transcription factor for osteoclastogenesis, and disrupted the formation of the actin ring in mature osteoclasts. In addition, genome-wide screening revealed that Btk regulates the expression of the genes involved in osteoclast differentiation and function in both an NFATc1-dependent and -independent manner. Finally, we showed that ibrutinib administration ameliorated the bone loss that developed in a RANKL-induced osteoporosis mouse model. Thus, this study suggests ibrutinib to be a promising therapeutic agent for osteoclast-associated bone diseases. Copyright © 2013 Elsevier Inc. All rights reserved.

Cancer-associated bone disease

PubMed Central

Body, J.-J.; Brandi, M.-L.; Cannata-Andia, J.; Chappard, D.; El Maghraoui, A.; Glüer, C.C.; Kendler, D.; Napoli, N.; Papaioannou, A.; Pierroz, D.D.; Rahme, M.; Van Poznak, C.H.; de Villiers, T.J.; El Hajj Fuleihan, G.

2016-01-01

Bone is commonly affected in cancer. Cancer-induced bone disease results from the primary disease, or from therapies against the primary condition, causing bone fragility. Bone-modifying agents, such as bisphosphonates and denosumab, are efficacious in preventing and delaying cancer-related bone disease. With evidence-based care pathways, guidelines assist physicians in clinical decision-making. Of the 57 million deaths in 2008 worldwide, almost two thirds were due to non-communicable diseases, led by cardiovascular diseases and cancers. Bone is a commonly affected organ in cancer, and although the incidence of metastatic bone disease is not well defined, it is estimated that around half of patients who die from cancer in the USA each year have bone involvement. Furthermore, cancer-induced bone disease can result from the primary disease itself, either due to circulating bone resorbing substances or metastatic bone disease, such as commonly occurs with breast, lung and prostate cancer, or from therapies administered to treat the primary condition thus causing bone loss and fractures. Treatment-induced osteoporosis may occur in the setting of glucocorticoid therapy or oestrogen deprivation therapy, chemotherapy-induced ovarian failure and androgen deprivation therapy. Tumour skeletal-related events include pathologic fractures, spinal cord compression, surgery and radiotherapy to bone and may or may not include hypercalcaemia of malignancy while skeletal complication refers to pain and other symptoms. Some evidence demonstrates the efficacy of various interventions including bone-modifying agents, such as bisphosphonates and denosumab, in preventing or delaying cancer-related bone disease. The latter includes treatment of patients with metastatic skeletal lesions in general, adjuvant treatment of breast and prostate cancer in particular, and the prevention of cancer-associated bone disease. This has led to the development of guidelines by several societies and working groups to assist physicians in clinical decision making, providing them with evidence-based care pathways to prevent skeletal-related events and bone loss. The goal of this paper is to put forth an IOF position paper addressing bone diseases and cancer and summarizing the position papers of other organizations. PMID:24146095

Simulated bone remodeling around two types of osseointegrated implants for direct fixation of upper-leg prostheses.

PubMed

Tomaszewski, P K; Verdonschot, N; Bulstra, S K; Rietman, J S; Verkerke, G J

2012-11-01

Direct attachment of an upper leg prosthesis to the skeletal system by a percutaneous implant is an alternative solution to the traditional socket fixation. In this study, we investigated long-term periprosthetic bone changes around two types of fixation implants using two different initial conditions, namely immediate post-amputation implantation and the conventional implantation after considerable time of socket prosthesis use. We questioned the difference in bone modeling response the implants provoked and if it could lead to premature bone fracture. Generic CT-based finite element models of an intact femoral bone and amputated bone implanted with models of two existing direct-fixation implants, the OPRA system (Integrum AB) and the ISP Endo/Exo prosthesis (ESKA Implants AG) were created for this study. Adaptive bone-remodeling simulations used the heel-strike and toe-off loads from a normal walking cycle. The bone loss caused by prolonged use of socket prosthesis had more severe effects on the ultimate bone quality than adaptation induced by the direct-fixation implants. Both implants showed considerable bone remodeling; the titanium screw implant (OPRA system) provoked more bone loss than the porous coated CoCrMo stem (ISP implant). The chance of the peri-prosthetic bone fracture remained higher for the post-socket case as compared to the direct amputation cases. In conclusion, both direct-fixation implants lead to considerable bone loss and bone loss is more severe after a prolonged period of post-socket use. Hence, from a biomechanical perspective it is better to limit the post-socket time and to re-design direct fixation devices to reduce bone loss and the probability of peri-prosthetic bone fractures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Diet-induced acidosis and alkali supplementation.

PubMed

Della Guardia, Lucio; Roggi, Carla; Cena, Hellas

2016-11-01

Western diet, high in protein-rich foods and poor in vegetables, is likely to be responsible for the development of a moderate acid excess leading to metabolism deregulation and the onset or worsening of chronic disturbances. Available findings seem to suggest that diets with high protein/vegetables ratio are likely to induce the development of calcium lithiasis, especially in predisposed subjects. Moreover, some evidence supports the hypothesis of bone metabolism worsening and enhanced bone loss following acid-genic diet consumption although available literature seems to lack direct and conclusive evidence demonstrating pathological bone loss. According to other evidences, diet-induced acidosis is likely to induce or accelerate muscle wasting or sarcopenia, especially among elderlies. Furthermore, recent epidemiological findings highlight a specific role of dietary acid load in glucose metabolism deregulation and insulin resistance. The aim of this review is to investigate the role of acid-genic diets in the development of the mentioned metabolic disorders focusing on the possible clinical improvements exerted by alkali supplementation.

Effects of habitual chitosan intake on bone mass, bone-related metabolic markers and duodenum CaBP D9K mRNA in ovariectomized SHRSP rats.

PubMed

Yang, Chu-Ya; Oh, Tae-Woong; Nakajima, Daito; Maeda, Atsuko; Naka, Tatsuki; Kim, Chang-Sun; Igawa, Shoji; Ohta, Fukio

2002-10-01

We have demonstrated that the habitual intake of chitosan can decrease bone mass in ovariectomized (OVX) SHRSP rats fed a low-Ca diet (0.1%). In the present study, we examined both the etiology of bone loss induced by dietary chitosan and the preventive effect of vitamin C supplementation. Rats were OVX and maintained on one of the following diets for 6 wk: 10% cellulose (CE). 10% chitosan (CH) or 10% chitosan with sodium ascorbate (CHVC). CH caused a significant reduction in bone mineral density (BMD) and stiffness in femurs and the fourth lumbar vertebrae (L4). There was no significant difference in intestinal Ca absorption between CH and CE, whereas CH intake significantly reduced intestinal P absorption. The bone loss in CH rats was accompanied with an increase in urinary Ca excretion and a decrease in serum Ca as well as a significant increment In serum PTH and 1,25(OH)2D3. The vitamin D receptor and calcium binding protein D9K mRNAs were also significantly increased in the duodenum of CH rats. Vitamin C supplementation to CH caused an increase in the Ca and P contents of femurs as well as BMD of the L4, with a decrease in urinary Ca excretion. These results indicate that dietary chitosan with low Ca intake possibly induces the loss of bone mass by enhancing urinary Ca excretion rather than by inhibiting Ca absorption, and that vitamin C supplementation could prevent bone loss caused by chitosan through the increment of retained Ca followed by suppression of urinary Ca excretion.

High-frequency, low-magnitude vibration does not prevent bone loss resulting from muscle disuse in mice following botulinum toxin injection.

PubMed

Manske, Sarah L; Good, Craig A; Zernicke, Ronald F; Boyd, Steven K

2012-01-01

High-frequency, low-magnitude vibration enhances bone formation ostensibly by mimicking normal postural muscle activity. We tested this hypothesis by examining whether daily exposure to low-magnitude vibration (VIB) would maintain bone in a muscle disuse model with botulinum toxin type A (BTX). Female 16-18 wk old BALB/c mice (N = 36) were assigned to BTX-VIB, BTX-SHAM, VIB, or SHAM. BTX mice were injected with BTX (20 µL; 1 U/100 g body mass) into the left hindlimb posterior musculature. All mice were anaesthetized for 20 min/d, 5 d/wk, for 3 wk, and the left leg mounted to a holder. Through the holder, VIB mice received 45 Hz, ± 0.6 g sinusoidal acceleration without weight bearing. SHAM mice received no vibration. At baseline and 3 wk, muscle cross-sectional area (MCSA) and tibial bone properties (epiphysis, metaphysis and diaphysis) were assessed by in vivo micro-CT. Bone volume fraction in the metaphysis decreased 12 ± 9% and 7 ± 6% in BTX-VIB and BTX-SHAM, but increased in the VIB and SHAM. There were no differences in dynamic histomorphometry outcomes between BTX-VIB and BTX nor between VIB and SHAM. Thus, vibration did not prevent bone loss induced by a rapid decline in muscle activity nor produce an anabolic effect in normal mice. The daily loading duration was shorter than would be expected from postural muscle activity, and may have been insufficient to prevent bone loss. Based on the approach used in this study, vibration does not prevent bone loss in the absence of muscle activity induced by BTX.

Response Of Mineralizing And Non-Mineralizing Bone Cells To Fluid Flow: An In Vitro Model For Mechanotransruction

NASA Technical Reports Server (NTRS)

Makuch, Lauren A.

2004-01-01

Humans reach peak bone mass at age 30. After this point, we lose 1 to 2 percent of bone mass each decade. In the microgravity environment of space, astronauts lose bone mass at an accelerated rate of 1 to 2 percent each month. When astronauts travel to Mars, they may be in space for as long as 3 years. During this time, they may lose about half of their bone mass from weight-bearing bones. This loss may be irreversible. The drastic loss in bone that astronauts experience in space makes them much more vulnerable to fractures. In addition, the corresponding removal of calcium from bone results in higher levels of calcium in the blood, which increases the risk of developing kidney stones. Currently, studies are being conducted which investigate factors governing bone adaptation and mechanotransduction. Bone is constantly adapting in response to mechanical stimuli. Increased mechanical loading stimulates bone formation and suppresses bone resorption. Reduction in mechanical loading caused by bedrest, disuse, or microgravity results in decreased bone formation and possibly increased bone resorption. Osteoblasts and osteoclasts are the two main cell types that participate in bone remodeling. Osteoblasts are anabolic (bone-forming) cells and osteoclasts are catabolic (bone-resorbing) cells. In microgravity, the activity of osteoblasts slows down and the activity of osteoclasts may speed up, causing a loss of bone density. Mechanotransduction, the molecular mechanism by which mechanical stimuli are converted to biochemical signals, is not yet understood. Exposure of cells to fluid flow imposes a shear stress on the cells. Several studies have shown that the shear stress that results from fluid flow induces a cellular response similar to that induced by mechanical loading. Thus, fluid flow can be used as an in vitro model to simulate the mechanical stress that bone cells experience in vivo. Previous in vitro studies have shown that fluid flow induces several responses in osteoblasts, including increased proliferation, osteoblastic differentiation, alkaline phosphatase activity, and production of nitric oxide, prostaglandins, and osteopontin. Several proteins have been implicated in osteoblastic mechanotransduction including Bone Morphogenetic Protein-2 (BMP-2), parathyroid hormone, 1,25-dihydroxyvitamin D3 receptor, osteopontin (OPN), osteoprotegerin (OPG), and alkaline phosphatase (AP). We will characterize relative levels of each protein in mineralizing or non-mineralizing MC3T3 osteoblastic cells that have been exposed to fluid flow compared to non-fluid flow using immunofluorescent staining and two- photon laser microscopy as well as western blotting. Because calcium-mediated pathways are important in osteoblastic signaling, we will transfect MC3T3 cells with cameleon probes for Ca2+ containing YFP and CFP. Results will be analyzed using FRET/FLIM to study differential release of intracellular Ca(2+) in response to fluid flow and conditions inducing matrix mineralization. In addition, we plan to conduct several microarray experiments to determine differential gene expression in MC3T3 cells in response to fluid flow and conditions inducing mineralization.

Role of human amnion-derived mesenchymal stem cells in promoting osteogenic differentiation by influencing p38 MAPK signaling in lipopolysaccharide -induced human bone marrow mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yuli; Wu, Hongxia; Shen, Ming

Periodontitis is a chronic inflammatory disease induced by bacterial pathogens, which not only affect connective tissue attachments but also cause alveolar bone loss. In this study, we investigated the anti-inflammatory effects of Human amnion-derived mesenchymal stem cells (HAMSCs) on human bone marrow mesenchymal stem cells (HBMSCs) under lipopolysaccharide (LPS)-induced inflammatory conditions. Proliferation levels were measured by flow cytometry and immunofluorescence staining of 5-ethynyl-2′-deoxyuridine (EdU). Osteoblastic differentiation and mineralization were investigated using chromogenic alkaline phosphatase activity (ALP) activity substrate assays, Alizarin red S staining, and RT-PCR analysis of HBMSCs osteogenic marker expression. Oxidative stress induced by LPS was investigated by assayingmore » reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity. Here, we demonstrated that HAMSCs increased the proliferation, osteoblastic differentiation, and SOD activity of LPS-induced HBMSCs, and down-regulated the ROS level. Moreover, our results suggested that the activation of p38 MAPK signal transduction pathway is essential for reversing the LPS-induced bone-destructive processes. SB203580, a selective inhibitor of p38 MAPK signaling, significantly suppressed the anti-inflammatory effects in HAMSCs. In conclusion, HAMSCs show a strong potential in treating inflammation-induced bone loss by influencing p38 MAPK signaling. - Highlights: • LPS inhibites osteogenic differentiation in HBMSCs via suppression of p38 MAPK signaling pathway. • HAMSCs promote LPS-induced HBMSCs osteogenic differentiation through p38 MAPK signaling pathway. • HAMSCs reverse LPS-induced oxidative stress in LPS-induced HBMSCs through p38 MAPK signaling pathway.« less

Effect of dietary fat/carbohydrate ratio on progression of alcoholic liver injury and bone loss in rats fed via total enteral nutrition (TEN)

USDA-ARS?s Scientific Manuscript database

Few studies have examined the effects of diet on the dynamics of injury progression or on alcohol-induced bone loss. In the current study, 300 g male Sprague-Dawley rats (N = 10/group) were treated with alcohol containing liquid diets via a stomach tube. Dietary fat content was either 5% (high carbo...

A novel role for dopamine signaling in the pathogenesis of bone loss from the atypical antipsychotic drug risperidone in female mice.

PubMed

Motyl, Katherine J; Beauchemin, Megan; Barlow, Deborah; Le, Phuong T; Nagano, Kenichi; Treyball, Annika; Contractor, Anisha; Baron, Roland; Rosen, Clifford J; Houseknecht, Karen L

2017-10-01

Atypical antipsychotic (AA) drugs, including risperidone (RIS), are used to treat schizophrenia, bipolar disorder, and autism, and are prescribed off-label for other mental health issues. AA drugs are associated with severe metabolic side effects of obesity and type 2 diabetes. Cross-sectional and longitudinal data also show that risperidone causes bone loss and increases fracture risk in both men and women. There are several potential mechanisms of bone loss from RIS. One is hypogonadism due to hyperprolactinemia from dopamine receptor antagonism. However, many patients have normal prolactin levels; moreover we demonstrated that bone loss from RIS in mice can be blocked by inhibition of β-adrenergic receptor activation with propranolol, suggesting the sympathetic nervous system (SNS) plays a pathological role. Further, when, we treated ovariectomized (OVX) and sham operated mice daily for 8weeks with RIS or vehicle we demonstrated that RIS causes significant trabecular bone loss in both sham operated and OVX mice. RIS directly suppressed osteoblast number in both sham and OVX mice, but increased osteoclast number and surface in OVX mice alone, potentially accounting for the augmented bone loss. Thus, hypogonadism alone cannot explain RIS induced bone loss. In the current study, we show that dopamine and RIS are present in the bone marrow compartment and that RIS can exert its effects directly on bone cells via dopamine receptors. Our findings of both direct and indirect effects of AA drugs on bone are relevant for current and future clinical and translational studies investigating the mechanism of skeletal changes from AA drugs. Copyright © 2017 Elsevier Inc. All rights reserved.

Preservation and promotion of bone formation in the mandible as a response to a novel calcium-phosphate based biomaterial in mineral deficiency induced low bone mass male versus female rats

PubMed Central

Srinivasan, Kritika; Naula, Diana P.; Mijares, Dindo Q.; Janal, Malvin N.; LeGeros, Raquel Z.; Zhang, Yu

2016-01-01

Calcium and other trace mineral supplements have previously demonstrated to safely improve bone quality. We hypothesize that our novel calcium-phosphate based biomaterial (SBM) preserves and promotes mandibular bone formation in male and female rats on mineral deficient diet (MD). Sixty Sprague-Dawley rats were randomly assigned to receive one of three diets (n = 10): basic diet (BD), MD or mineral deficient diet with 2% SBM. Rats were sacrificed after 6 months. Micro-Computed Tomography (μCT) was used to evaluate bone volume and 3D-microarchitecture while microradiography (Faxitron) was used to measure bone mineral density from different sections of the mandible. Results showed that bone quality varied with region, gender and diet. MD reduced bone mineral density (BMD) and volume and increased porosity. SBM preserved BMD and bone mineral content (BMC) in the alveolar bone and condyle in both genders. In the alveolar crest and mandibular body, while preserving more bone in males, SBM also significantly supplemented female bone. Results indicate that mineral deficiency leads to low bone mass in skeletally immature rats, comparatively more in males. Furthermore, SBM administered as a dietary supplement was effective in preventing mandibular bone loss in all subjects. This study suggests that the SBM preparation has potential use in minimizing low peak bone mass induced by mineral deficiency and related bone loss irrespective of gender. PMID:26914814

Dynamic Foot Pressure as a Countermeasure to Muscle Atrophy

NASA Astrophysics Data System (ADS)

Kyparos, A.; Layne, C. S.; Martinez, D. A.; Clarke, M. S. F.; Feeback, D. L.

2002-01-01

Mechanical unloading of skeletal muscle (SKM) as a consequence of space flight or ground-based analogues, such as human bedrest and rodent hindlimb suspension (HLS) models, induces SKM atrophy particularly affecting the anti-gravity musculature of the lower limbs. In the context of manned space flight, the subsequent loss of muscle strength and functionality will pose operational implications jeopardizing mission success. Exercise, currently the primary muscle degradation countermeasure, has not proven completely effective in preventing muscle atrophy. It is therefore imperative that some other forms of in- flight countermeasure be also developed to supplement the prescribed exercise regimen the astronauts follow during spaceflight. Previous work in both humans and rats has shown that mechanical stimulation of the soles of the feet increases neuromuscular activation in the lower limb musculature and that such stimulation results in the limited prevention of atrophy in the soleus muscle of unloaded rats. This study was designed to investigate the effect of cutaneous mechanoreceptor stimulation on hindlimb unloading- induced SKM atrophy in rats. It was hypothesized that mechanical stimulation of the plantar surface of the rat foot during hindlimb suspension (HLS), utilizing a novel stimulation paradigm known as Dynamic Foot Pressure (DFP), would attenuate unloading-induced SKM atrophy. Mature adult male Wistar rats were randomly assigned to four groups of 10 rats each as follows: sedentary controls (Ctrl), hindlimb suspended only (HLS), hindlimb suspended wearing an inflatable boot (HLS-IFL) and hindlimb suspended rats wearing a non-inflatable boot (HLS-NIFL). The stimulation of mechanoreceptors was achieved by applying pressure to the plantar surface of the foot during the 10-day period of HLS using a custom-built boot. The anti-atrophic effects of DFP application was quantified directly by morphological (muscle wet weight, myofiber cross-sectional area, neuromuscular junction size/density), histochemical (myofiber type distribution) and biochemical (myosin heavy chain-MHC isoform content, muscle collagen concentration and maturation) analysis techniques in the soleus, medial gastrocnemius, and tibialis anterior muscles. The results indicated that the application of DFP ameliorated hindlimb-induced SKM atrophy. It is postulated that this effect was achieved via proprioceptive pathways as a consequence of DFT mimicking the neuromuscular activity/contraction patterns normally induced by load bearing in specific anti-gravity muscles of the lower limbs in a terrestrial environment. The underlined concept promises to serve as the basis for developing a novel supplemental to exercise during space flight countermeasure as well as an effective rehabilitation technique for bed-ridden patients.

A high-fat diet increases body weight and circulating estradiol concentrations but does not improve bone structural properties in ovariectomized mice.

PubMed

Cao, Jay J; Gregoire, Brian R

2016-04-01

Bone health is influenced by body mass and estrogen. The objective of the study was to determine whether high-fat diet-induced obesity affects bone structure and alters markers of bone turnover in ovariectomized (OVX) mice. We hypothesized that a high-fat diet would increase body weight gain and serum estradiol levels in OVX mice but would not improve bone structural parameter in OVX mice. Thirty-five C57BL/6 mice were either sham operated or OVX at the age of 4 months and then fed either a normal-fat diet (10% energy as fat) or a high-fat diet (45% energy as fat with extra fat from lard) ad libitum for 11 weeks. Ovariectomy increased body weight, serum tartrate-resistant acid phosphatase concentration, and expression of cathepsin K in bone; decreased serum estradiol concentration; and induced significant bone loss manifested by decreased bone volume/total volume (BV/TV), connectivity density (Conn.D), trabecular number, and trabecular thickness with increased trabecular separation and structural model index (P < .01). The high-fat diet increased body weight (P < .01) in OVX mice and nonsignificantly decreased BV/TV (P = .08) and Conn.D (P = .10). Despite having similar serum estradiol concentrations and higher body weight, OVX mice consuming the high-fat diet had lower BV/TV, Conn.D, trabecular number, trabecular thickness, and higher structural model index and trabecular separation than did sham mice fed the normal-fat diet. These findings indicate that increased body weight and elevated serum estradiol concentration induced by a high-fat diet do not mitigate ovariectomy-induced bone loss in mice. Published by Elsevier Inc.

Dynamic Foot Stimulation Attenuates Soleus Muscle Atrophy Induced by Hindlimb Unloading in Rats

NASA Technical Reports Server (NTRS)

Kyparos, Antonios; Feeback, Daniel L.; Layne, Charles S.; Martinez, Daniel A.; Clarke, Mark S. F.

2004-01-01

Unloading-induced myofiber atrophy is a phenomenon that occurs in the aging population, bed-ridden patients and astronauts. The objective of this study was to determine whether or not dynamic foot stimulation (DFS) applied to the plantar surface of the rat foot can serve as a countermeasure to the soleus muscle atrophy normally observed in hindlimb unloaded (HU) rats. Thirty mature adult (6-month-old) male Wistar rats were randomly assigned into ambulatory control (AMB), hindlimb unloaded alone (HU), or hindlimb unloaded with the application of DFS (HU+DFS) groups. A dynamic pattern of pressure was applied to the right foot of each HU animal using a specially fabricated boot containing an inflatable air bladder connected to a solenoid air pump controlled by a laptop computer. The anti-atrophic effects of DFS were quantified morphometrically in frozen cross-sections of soleus muscle stained using the metachromatic-ATPase fiber typing technique. Application of DFS during HU significantly counteracted the atrophic response observed in the soleus by preventing approximately 85% of the reduction in Type I myofiber cross-sectional area (CSA) observed during HU. However, DFS did not protect type II fibers of the soleus from HU-induced atrophy or any fiber type in the soleus muscle of the contralateral control leg of the DFS-treated HU animals. These results illustrate that the application of DFS to the rat foot is an effective countermeasure to soleus muscle atrophy induced by HU.

Cell Mechanisms of Bone Tissue Loss Under Space Flight Conditions

NASA Astrophysics Data System (ADS)

Rodionova, Natalia

Investigations on the space biosatellites has shown that the bone skeleton is one of the most im-portant targets of the effect space flight factors on the organism. Bone tissue cells were studied by electron microscopy in biosamples of rats' long bones flown on the board american station "SLS-2" and in experiments with modelling of microgravity ("tail suspension" method) with using autoradiography. The analysis of data permits to suppose that the processes of remod-eling in bone tissue at microgravity include the following succession of cell-to-cell interactions. Osteocytes as mechanosensory cells are first who respond to a changing "mechanical field". The next stage is intensification of osteolytic processes in osteocytes, leading to a volume en-largement of the osteocytic lacunae and removal of the "excess bone". Then mechanical signals have been transmitted through a system of canals and processes of the osteocytic syncitium to certain superficial bone zones and are perceived by osteoblasts and bone-lining cells (superficial osteocytes), as well as by the bone-marrow stromal cells. The sensitivity of stromal cells, pre-osteoblasts and osteoblasts, under microgravity was shown in a number of works. As a response to microgravity, the system of stromal cells -preosteoblasts -osteoblasts displays retardation of proliferation, differentiation and specific functions of osteogenetic cells. This is supported by the 3H-thymidine studies of the dynamics of differentiation of osteogenetic cells in remodeling zones. But unloading is not adequate and in part of the osteocytes are apoptotic changes as shown by our electron microscopic investigations. An osteocytic apoptosis can play the role in attraction the osteoclasts and in regulation of bone remodeling. The apoptotic bodies with a liquid flow through a system of canals are transferred to the bone surface, where they fulfil the role of haemoattractants for monocytes come here and form osteoclasts. The osteoclasts destroy bone tissue. The macrophages are incorporated into resorption lacunaes and utilize the organic matrix and cellular detritus. The products are secreted to remodeling zones and act as haemoattractants for recruiting and subsequent differentiation here of the osteogenic precursor cells. However, as shown by our results with 3H-glycine, in absence of mechanical stimulus the activization of osteoblastogenesis either doesn't occur, or takes place on a smaller scale. According to our electron-microscopic data a load deficit leads to an adaptive differentiation of fibroblasts and adipocytes in this remodeling zones. This sequence of events is considered as a mechanism of bone tissue loss which underlies the development of osteopenia and osteoporosis under space flight condition.

Bone and Calcium Metabolism During Space Flight

NASA Technical Reports Server (NTRS)

Smith, Scott M.

2004-01-01

Understanding bone loss during space flight is one of the most critical challenges for maintaining astronaut health on space exploration missions. Flight and ground-based studies have been conducted to better understand the nature and mechanisms of weightlessness-induced bone loss, and to identify a means to counteract the loss. Maintenance of bone health requires a balance between bone formation and bone resorption. Early space research identified bone loss as a critical health issue, but could not provide a distinction between the bone formation and breakdown processes. The recent identification of collagen crosslinks as markers of bone resorption has made possible a clear understanding that a decrease in bone resorption is an important effect of space flight, with bone formation being unchanged or only slightly decreased. Calcium regulatory factors have also been studied, in an attempt to understand their role in bone loss. The lack of ultraviolet light exposure and insufficient dietary sources of vitamin D often lead to reduced vitamin D stores on long-duration flights. Serum parathyroid hormone (PTH) concentrations are decreased during flight compared to before flight, although small subject numbers often make this hard to document statistically. As expected, reduced PTH concentrations are accompanied by reduced 1,25-dihydroxyvitamin D concentrations. Calcium kinetic studies during space flight confirm and extend the information gained from biochemical markers of bone metabolism. Calcium kinetic studies demonstrate that bone resorption is increased, bone formation is unchanged or decreased, and dietary calcium absorption is reduced during space flight. Evaluations have also been conducted of countermeasures, including dietary, exercise, and pharmacological treatments. In recent studies, many potential countermeasures show promise at mitigating bone loss in ground-based analogs of weightlessness (e.g., bed rest), but require further ground and flight testing to ensure that the beneficial effects are seen in space flight. As we begin to plan for missions to go back to the Moon, and even off to Mars, many questions are yet to be answered. Maintaining bone is one of the greatest challenges, but with a better understanding of the mechanical processes of bone loss, countermeasures can be designed more efficiently, and the solution (or solutions) may be just over the horizon.

Bone Research at NASA: Career Pathway to the Space Program

NASA Technical Reports Server (NTRS)

Sibonga, Jean D.

2007-01-01

This viewgraph document is comprised of two presentations about Bone Research at NASA. The first document has slides that show the percent of bone loss from specific bones as demonstrated from research of the Mir cosmonauts, and the required preflight and postflight BMD measurements for long duration flights. The second presentation entitled "Recovery of Spaceflight-induced Bone Loss: Bone Mineral Density after Long-duration Missions as Fitted with an Exponential Function" reviews the recovery of Bone Mineral Density (BMD) after long duration missions. Between 1990 and 2004, 56 missions were flown with 45 crewmembers for an average of 181 days +/- 47 days. For each of these flights the change in BMD was calculated after the flight. The BMD changes were plotted against the number of days for bone recovery after the landing. The plots for the bones that were measured are shown.

Rhizoma Dioscoreae Extract Protects against Alveolar Bone Loss in Ovariectomized Rats via microRNAs Regulation

PubMed Central

Zhang, Zhiguo; Song, Changheng; Zhang, Fangzhen; Xiang, Lihua; Chen, Yanjing; Li, Yan; Pan, Jinghua; Liu, Hong; Xiao, Gary Guishan; Ju, Dahong

2015-01-01

The aim of this study was to evaluate the osteoprotective effect of aqueous Rhizoma Dioscoreae extract (RDE) on the alveolar bone of rats with ovariectomy-induced bone loss. Female Wistar rats underwent either ovariectomy or sham operation (SHAM). The ovariectomized (OVX) rats were treated with vehicle (OVX), estradiol valerate (EV), or RDE. After treatments, the bone mineral density (BMD) and the three-dimensional microarchitecture of the alveolar bone were analyzed to assess bone mass. Microarrays were used to evaluate microRNA expression profiles in alveolar bone from RDE-treated and OVX rats. The differential expression of microRNAs was validated using real-time quantitative RT-PCR (qRT-PCR), and the target genes of validated microRNAs were predicted and further analyzed using Ingenuity Pathway Analysis (IPA). The key findings were verified using qRT-PCR. Our results show that RDE inhibits alveolar bone loss in OVX rats. Compared to the OVX rats, the RDE-treated rats showed upregulated expression levels of 8 microRNAs and downregulated expression levels of 8 microRNAs in the alveolar bone in the microarray analysis. qRT-PCR helped validate 13 of 16 differentially expressed microRNAs, and 114 putative target genes of the validated microRNAs were retrieved. The IPA showed that these putative target genes had the potential to code for proteins that were involved in the transforming growth factor (TGF)-β/bone morphogenetic proteins (BMPs)/Smad signaling pathway (Tgfbr2/Bmpr2, Smad3/4/5, and Bcl-2) and interleukin (IL)-6/oncostatin M (OSM)/Jak1/STAT3 signaling pathway (Jak1, STAT3, and Il6r). These experiments revealed that RDE could inhibit ovariectomy-induced alveolar bone loss in rats. The mechanism of this anti-osteopenic effect in alveolar bone may involve the simultaneous inhibition of bone formation and bone resorption, which is associated with modulation of the TGF-β/BMPs/Smad and the IL-6/OSM/Jak1/STAT3 signaling pathways via microRNA regulation. PMID:25690421

Rhizoma Dioscoreae extract protects against alveolar bone loss in ovariectomized rats via microRNAs regulation.

PubMed

Zhang, Zhiguo; Song, Changheng; Zhang, Fangzhen; Xiang, Lihua; Chen, Yanjing; Li, Yan; Pan, Jinghua; Liu, Hong; Xiao, Gary Guishan; Ju, Dahong

2015-02-16

The aim of this study was to evaluate the osteoprotective effect of aqueous Rhizoma Dioscoreae extract (RDE) on the alveolar bone of rats with ovariectomy-induced bone loss. Female Wistar rats underwent either ovariectomy or sham operation (SHAM). The ovariectomized (OVX) rats were treated with vehicle (OVX), estradiol valerate (EV), or RDE. After treatments, the bone mineral density (BMD) and the three-dimensional microarchitecture of the alveolar bone were analyzed to assess bone mass. Microarrays were used to evaluate microRNA expression profiles in alveolar bone from RDE-treated and OVX rats. The differential expression of microRNAs was validated using real-time quantitative RT-PCR (qRT-PCR), and the target genes of validated microRNAs were predicted and further analyzed using Ingenuity Pathway Analysis (IPA). The key findings were verified using qRT-PCR. Our results show that RDE inhibits alveolar bone loss in OVX rats. Compared to the OVX rats, the RDE-treated rats showed upregulated expression levels of 8 microRNAs and downregulated expression levels of 8 microRNAs in the alveolar bone in the microarray analysis. qRT-PCR helped validate 13 of 16 differentially expressed microRNAs, and 114 putative target genes of the validated microRNAs were retrieved. The IPA showed that these putative target genes had the potential to code for proteins that were involved in the transforming growth factor (TGF)-β/bone morphogenetic proteins (BMPs)/Smad signaling pathway (Tgfbr2/Bmpr2, Smad3/4/5, and Bcl-2) and interleukin (IL)-6/oncostatin M (OSM)/Jak1/STAT3 signaling pathway (Jak1, STAT3, and Il6r). These experiments revealed that RDE could inhibit ovariectomy-induced alveolar bone loss in rats. The mechanism of this anti-osteopenic effect in alveolar bone may involve the simultaneous inhibition of bone formation and bone resorption, which is associated with modulation of the TGF-β/BMPs/Smad and the IL-6/OSM/Jak1/STAT3 signaling pathways via microRNA regulation.

Capacity of omega-3 fatty acids or eicosapentaenoic acid to counteract weightlessness-induced bone loss by inhibiting NF-kappaB activation: from cells to bed rest to astronauts.

PubMed

Zwart, Sara R; Pierson, Duane; Mehta, Satish; Gonda, Steve; Smith, Scott M

2010-05-01

NF-kappaB is a transcriptional activator of many genes, including some that lead to muscle atrophy and bone resorption-significant concerns for astronauts. NF-kappaB activation is inhibited by eicosapentaenoic acid (EPA), but the influence of this omega-3 fatty acid on the effects of weightlessness are unknown. We report here cellular, ground analogue, and spaceflight findings. We investigated the effects of EPA on differentiation of RAW264.7 monocyte/macrophage cells induced by receptor activator of NF-kappaB ligand (RANKL) and on activation of NF-kappaB by tumor necrosis factor alpha (TNF-alpha) or exposure to modeled weightlessness. EPA (50 microM for 24 hours) inhibited RANKL-induced differentiation and decreased activation of NF-kappaB induced by 0.2 microg/mL of TNF-alpha for 30 minutes or by modeled weightlessness for 24 hours (p < .05). In human studies, we evaluated whether NF-kappaB activation was altered after short-duration spaceflight and determined the relationship between intake of omega-3 fatty acids and markers of bone resorption during bed rest and the relationship between fish intake and bone mineral density after long-duration spaceflight. NF-kappaB was elevated in crew members after short-duration spaceflight, and higher consumption of fish (a rich source of omega-3 fatty acids) was associated with reduced loss of bone mineral density after flight (p < .05). Also supporting the cell study findings, a higher intake of omega-3 fatty acids was associated with less N-telopeptide excretion during bed rest (Pearson r = -0.62, p < .05). Together these data provide mechanistic cellular and preliminary human evidence of the potential for EPA to counteract bone loss associated with spaceflight. (c) 2010 American Society for Bone and Mineral Research.

Cannabidiol decreases bone resorption by inhibiting RANK/RANKL expression and pro-inflammatory cytokines during experimental periodontitis in rats.

PubMed

Napimoga, Marcelo H; Benatti, Bruno B; Lima, Flavia O; Alves, Polyanna M; Campos, Alline C; Pena-Dos-Santos, Diego R; Severino, Fernando P; Cunha, Fernando Q; Guimarães, Francisco S

2009-02-01

Cannabidiol (CBD) is a cannabinoid component from Cannabis sativa that does not induce psychotomimetic effects and possess anti-inflammatory properties. In the present study we tested the effects of CBD in a periodontitis experimental model in rats. We also investigated possible mechanisms underlying these effects. Periodontal disease was induced by a ligature placed around the mandible first molars of each animal. Male Wistar rats were divided into 3 groups: control animals; ligature-induced animals treated with vehicle and ligature-induced animals treated with CBD (5 mg/kg, daily). Thirty days after the induction of periodontal disease the animals were sacrificed and mandibles and gingival tissues removed for further analysis. Morphometrical analysis of alveolar bone loss demonstrated that CBD-treated animals presented a decreased alveolar bone loss and a lower expression of the activator of nuclear factor-kappaB ligand RANKL/RANK. Moreover, gingival tissues from the CBD-treated group showed decreased neutrophil migration (MPO assay) associated with lower interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha production. These results indicate that CBD may be useful to control bone resorption during progression of experimental periodontitis in rats.

High fat diet attenuates hyperglycemia, body composition changes, and bone loss in male streptozotocin-induced type 1 diabetic mice.

PubMed

Carvalho, Adriana Lelis; DeMambro, Victoria E; Guntur, Anyonya R; Le, Phuong; Nagano, Kenichi; Baron, Roland; de Paula, Francisco José Albuquerque; Motyl, Katherine J

2018-02-01

There is a growing and alarming prevalence of obesity and the metabolic syndrome in type I diabetic patients (T1DM), particularly in adolescence. In general, low bone mass, higher fracture risk, and increased marrow adipose tissue (MAT) are features of diabetic osteopathy in insulin-deficient subjects. On the other hand, type 2 diabetes (T2DM) is associated with normal or high bone mass, a greater risk of peripheral fractures, and no change in MAT. Therefore, we sought to determine the effect of weight gain on bone turnover in insulin-deficient mice. We evaluated the impact of a 6-week high-fat (HFD) rich in medium chain fatty acids or low-fat diet (LFD) on bone mass and MAT in a streptozotocin (STZ)-induced model using male C57BL/6J mice at 8 weeks of age. Dietary intervention was initiated after diabetes confirmation. At the endpoint, lower non-fasting glucose levels were observed in diabetic mice fed with high fat diet compared to diabetic mice fed the low fat diet (STZ-LFD). Compared to euglycemic controls, the STZ-LFD had marked polydipsia and polyphagia, as well as reduced lean mass, fat mass, and bone parameters. Interestingly, STZ-HFD mice had higher bone mass, namely less cortical bone loss and more trabecular bone than STZ-LFD. Thus, we found that a HFD, rich in medium chain fatty acids, protects against bone loss in a T1DM mouse model. Whether this may also translate to T1DM patients who are overweight or obese in respect to maintenance of bone mass remains to be determined through longitudinal studies. © 2017 Wiley Periodicals, Inc.

A Biomechanical Approach to Assessing Hip Fracture Risk

NASA Technical Reports Server (NTRS)

Ellman, Rachel

2009-01-01

Bone loss in microgravity is well documented, but it is difficult to quantify how declines in bone mineral density (BMD) contribute to an astronaut's overall risk of fracture upon return. This study uses a biomechanical approach to assessing hip fracture risk, or Factor of Risk (Phi), which is defined as the ratio of applied load to bone strength. All long-duration NASA astronauts from Expeditions 1-18 were included in this study (n=25), while crewmembers who flew twice (n=2) were treated as separate subjects. Bone strength was estimated based on an empirical relationship between areal BMD at the hip, as measured by DXA, and failure load, as determined by mechanical testing of cadaver femora. Fall load during a sideways fall was calculated from a previously developed biomechanical model, which takes into account body weight, height, gender, and soft tissue thickness overlying the lateral aspect of the hip that serves to attenuate the impact force. While no statistical analyses have been performed yet, preliminary results show that males in this population have a higher FOR than females, with a post- flight Phi of 0.87 and 0.36, respectively. FOR increases 5.1% from preflight to postflight, while only one subject crossed the fracture "threshold" of Phi = 1, for a total of 2 subjects with a postflight Phi > 1. These results suggest that men may be at greater risk for hip fracture due largely in part to their relatively thin soft tissue padding as compared to women, since soft tissue thickness has the highest correlation (R(exp 2)= .53) with FOR of all subject-specific parameters. Future work will investigate changes in FOR during recovery to see if baseline risk levels are restored upon return to 1-g activity. While dual x-ray absorptiometry (DXA) is the most commonly used clinical measure of bone health, it fails to provide compartment-specific information that is useful in assessing changes to bone quality as a result of microgravity exposure. Peripheral quantitative computed tomography (pQCT) accomplishes this by imaging transverse "slices" of the long bones. This project was a re-analysis of a 90 day bed rest study to determine if changes to cortical and trabecular compartments could be detected in the distal tibia with statistical significance using a new pQCT image analysis method. Nearly all changes in bone mineral density (BMD) and cross sectional area (CSA) measures were seen with statistical significance, with the exception of a change in cortical BMD. Total bone CSA increased by 1.1 % (p =0.01), cortical CSA decreased by - 5.6% (p<0.001) and trabecular CSA increased by 1.76% (p=0.007); the combination of which suggests bone resorption occurred at the endocortical surface in response to mechanical unloading by bed rest. Furthermore, total BMD and trabecular BMD decreased (-3.8%, p=0.001 and -2.8%, p =0.007, respectively), while decreases in cortical BMD failed to reach significance (-1.2%, p=0.07). Given that compartment-specific changes are seen with significance and are likely to influence bone strength, it is recommended that pQCT remain a standard measure used in bed rest because it provides a unique measure by which to better evaluate the efficacy of countermeasures to microgravity-induced bone loss.

Changes in Cartilage Morphology of the Knee after 14-days of Bed Rest

NASA Astrophysics Data System (ADS)

Liphardt, A.-M.; Mündermann, A.; Koo, S.; Bäcker, N.; Andriacchi, T.; Zange, J.; Mester, J.; Heer, M.

Introduction While there are still many unanswered questions related to the effects of space flight and disuse on cartilage health and cartilage morphology the number of in vivo experiments in humans is small For muscle and bone tissue it is well known that unloading results in degeneration of those tissues Also for cartilage previous studies in patients suggest that unloading causes cartilage degeneration Studies using immobilization as a model of unloading help to investigate the importance of experiencing mechanical loads for the maintenance of healthy biological tissues The goal of our study was to investigate whether bed rest induced immobilization has a negative effect on articular cartilage in healthy subjects and if vibration training is a potential counter-measure for these negative effects Methods Eight male healthy subjects 78 1 pm 9 5 kg 179 pm 9 6 cm 26 pm 5 years performed a 14-day bed rest in 6 r -head down tilt HDT The study was designed in a cross-over-design where each subject received a training intervention vib in one phase and no intervention con in the other phase During the training intervention subjects trained 2 x 5-minutes per day at 20 Hz with 2 -- 4 mm amplitude on a vibration plate Galileo 900 Magnet resonance MR imaging of the right knee was performed to measure articular cartilage thickness MR-images 2 mm slice thickness 0 35 mm x 0 35 mm in-plane resolution 448 x 512 pixels were taken before and after bed rest to investigate the effects of bed rest

Osthole Stimulates Osteoblast Differentiation and Bone Formation by Activation of β-Catenin–BMP Signaling

PubMed Central

Tang, De-Zhi; Hou, Wei; Zhou, Quan; Zhang, Minjie; Holz, Jonathan; Sheu, Tzong-Jen; Li, Tian-Fang; Cheng, Shao-Dan; Shi, Qi; Harris, Stephen E; Chen, Di; Wang, Yong-Jun

2010-01-01

Osteoporosis is defined as reduced bone mineral density with a high risk of fragile fracture. Current available treatment regimens include antiresorptive drugs such as estrogen receptor analogues and bisphosphates and anabolic agents such as parathyroid hormone (PTH). However, neither option is completely satisfactory because of adverse effects. It is thus highly desirable to identify novel anabolic agents to improve future osteoporosis treatment. Osthole, a coumarin-like derivative extracted from Chinese herbs, has been shown to stimulate osteoblast proliferation and differentiation, but its effect on bone formation in vivo and underlying mechanism remain unknown. In this study, we found that local injection of Osthole significantly increased new bone formation on the surface of mouse calvaria. Ovariectomy caused evident bone loss in rats, whereas Osthole largely prevented such loss, as shown by improved bone microarchitecture, histomorphometric parameters, and biomechanical properties. In vitro studies demonstrated that Osthole activated Wnt/β-catenin signaling, increased Bmp2 expression, and stimulated osteoblast differentiation. Targeted deletion of the β-catenin and Bmp2 genes abolished the stimulatory effect of Osthole on osteoblast differentiation. Since deletion of the Bmp2 gene did not affect Osthole-induced β-catenin expression and the deletion of the β-catenin gene inhibited Osthole-regulated Bmp2 expression in osteoblasts, we propose that Osthole acts through β-catenin–BMP signaling to promote osteoblast differentiation. Our findings demonstrate that Osthole could be a potential anabolic agent to stimulate bone formation and prevent estrogen deficiency–induced bone loss. © 2010 American Society for Bone and Mineral Research. PMID:20200936

Bone remodeling and calcium homeostasis in patients with spinal cord injury: a review.

PubMed

Maïmoun, Laurent; Fattal, Charles; Sultan, Charles

2011-12-01

Patients with spinal cord injury exhibit early and acute bone loss with the major functional consequence being a high incidence of pathological fractures. The bone status of these patients is generally investigated by dual-energy x-ray absorptiometry, but this technique does not reveal the pathophysiological mechanism underlying the bone loss. Bone cell activity can be indirectly evaluated by noninvasive techniques, including measurement of specific biochemical markers of bone formation (such as osteocalcin or bone-alkaline phosphatase) and resorption (such as procollagen type I N- or C-terminal propeptide). The bone loss in spinal cord injury is clearly due to an uncoupling of bone remodeling in favor of bone resorption, which starts just after the injury and peaks at about 1 to 4 months. Beyond 6 months, bone resorption activity decreases progressively but remains elevated for many years after injury. Conversely, bone formation is less affected. Antiresorptive treatment induces an early and acute reduction in bone resorption markers. Level of injury and health-related complications do not seem to be implicated in the intensity of bone resorption. During the acute phase, the hypercalcemic status is associated with the suppression of parathyroid hormone and vitamin D metabolites. The high sensitivity of these markers after treatment suggests that they can be used for monitoring treatment efficacy and patient compliance. The concomitant use of bone markers and dual-energy x-ray absorptiometry may improve the physician's ability to detect patients at risk of severe bone loss and subsequent fractures. Copyright © 2011 Elsevier Inc. All rights reserved.

Bone healing response in cyclically loaded implants: Comparing zero, one, and two loading sessions per day.

PubMed

de Barros E Lima Bueno, Renan; Dias, Ana Paula; Ponce, Katia J; Wazen, Rima; Brunski, John B; Nanci, Antonio

2018-05-31

When bone implants are loaded, they are inevitably subjected to displacement relative to bone. Such micromotion generates stress/strain states at the interface that can cause beneficial or detrimental sequels. The objective of this study is to better understand the mechanobiology of bone healing at the tissue-implant interface during repeated loading. Machined screw shaped Ti implants were placed in rat tibiae in a hole slightly bigger than the implant diameter. Implants were held stable by a specially-designed bone plate that permits controlled loading. Three loading regimens were applied, (a) zero loading, (b) one daily loading session of 60 cycles with an axial force of 1.5 N/cycle for 7 days, and (c) two such daily sessions with the same axial force also for 7 days. Finite element analysis was used to characterize the mechanobiological conditions produced by the loading sessions. After 7 days, the implants with surrounding interfacial tissue were harvested and processed for histological, histomorphometric and DNA microarray analyses. Histomorphometric analyses revealed that the group subjected to repeated loading sessions exhibited a significant decrease in bone-implant contact and increase in bone-implant distance, as compared to unloaded implants and those subjected to only one loading session. Gene expression profiles differed during osseointegration between all groups mainly with respect to inflammatory and unidentified gene categories. The results indicate that increasing the daily cyclic loading of implants induces deleterious changes in the bone healing response, most likely due to the accumulation of tissue damage and associated inflammatory reaction at the bone-implant interface. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

The Effects of Ligustrazine on the Ca2+ Concentration of Soleus and Gastrocnemius Muscle Fibers in Hindlimb Unloaded Rat

NASA Astrophysics Data System (ADS)

Gao, Yunfang; Goswami, Nandu; Du, Bei; Hu, Huanxin; Wu, Xue

Background Spaceflight or inactivity (bed rest, limb immobilization, hindlimb unloading) causes skeletal muscle atrophy. Recent studies show that an increase in protein degradation is an important mechanism for disuse atrophy. Furthermore, the calcium overload of disuse-atrophied muscle fiber has been shown to initiate the skeletal muscle proteolysis in disuse atrophy. Ligustrazine (tetramethylpyrazine, TMP), one of the important active ingredient extracted from Chuanxiong, has been shown by our group to increase muscle fiber cross-sectional area in atrophied soleus induced by 14 days hindlimb unloading. However, the underlying mechanisms of ligustrazine effects on disuse-atrophied muscle fibers remain unknown. Objective: We investigated the effects of ligustrazine on the cytoplasmic calcium overloading in soleus and gastrocnemius in 14 days hindlimb unloaded (HU) rats. Methods: Adult female Sprague-Dawley rats were matched for body mass and randomly assigned to three groups (n=8, each group): 1) synchronous control (CON); HU + intragastric water instillation (HU+W); HU + intragastric 60.0 mg kg-1 ligustrazine instillation (HU+Tmp). Laser scanning confocal microscope assessed the concentrations of cytoplasmic calcium ions. Spaceflight disuse atrophy was simulated by hindlimb unloading, provided by tail suspension. Results: 1) Compared with CON, the concentration of soleus intracellular calcium ion in HU+W and HU+Tmp increased 330% and 86% respectively P<0.01). Compared with HU+W, the concentration of soleus intracellular calcium ion in HU+Tmp decreased by 130% P<0.01). 2) Compared with CON, the concentration of gastrocnemius intracellular calcium ion in HU+W and HU+Tmp increased 189.8% and 32.1% respectively P<0.01). Compared with HU+W, the concentration of gastrocnemius intracellular calcium ion in HU+Tmp decreased by 119.3% (P<0.01). Conclusion: After 14 days of hindlimb unloading, cytoplasmic calcium of soleus (slow-twitch muscle) and gastrocnemius (fast-twitch muscle) showed significant overload. This was especially true for the soleus. Ligustrazine appears to inhibit the cytoplasmic calcium overload thus leadig to lesser muscle atrophy in hindlimb unloaded animals. Therefore, ligustrazine may play important role in preventing muscle loss during spaceflight. Key words: Ligustrazine; Tetramethylpyrazine; disuse atrophy; calcium overload; soleus; gastrocnemius; spaceflight This work was supported by funds from the National Natural Science Foundation of China (Grant No. 31270455), International Scientific and Technological Cooperation Projects in Shaanxi Province of China (Grant No. 2013KW26-01).

Subtraction micro-computed tomography of angiogenesis and osteogenesis during bone repair using synchrotron radiation with a novel contrast agent.

PubMed

Matsumoto, Takeshi; Goto, Daichi; Sato, Syota

2013-09-01

Quantitative three-dimensional (3D) imaging of angiogenesis during bone repair remains an experimental challenge. We developed a novel contrast agent containing 0.07- to 0.1-μm particles of zirconium dioxide (ZrCA) and established subtraction μCT using synchrotron radiation (sSRCT) for quantitative imaging of angiogenesis and bone repair. This method was applied to a rat model of tibial bone repair 3 days (DAY3; n = 2), 5 days (DAY5; n = 8), or 10 days (DAY10; n = 8) after drill-hole injury. Using the same drill-hole defect model, its potential use was illustrated by comparison of bone repair between hindlimbs subjected to mechanical unloading (n = 6) and normal weight bearing (n = 6) for 10 days. Following vascular casting with ZrCA, the defect site was scanned with 17.9- and 18.1-keV X-rays. In the latter, image contrast between ZrCA-filled vasculature and bone was enhanced owing to the sharp absorption jump of zirconium dioxide at 18.0 keV (k-edge). The two scan data sets were reconstructed with 2.74-μm voxel resolution, registered by mutual information, and digitally subtracted to extract the contrast-enhanced vascular image. K2HPO4 phantom solutions were scanned at 17.9 keV for quantitative evaluation of bone mineral. Angiogenesis had already started, but new bone formation was not found on DAY3. New bone emerged near the defect boundary on DAY5 and took the form of trabecular-like structure invaded by microvessels on DAY10. Vascular and bone volume fractions, blood vessel and bone thicknesses, and mineralization were higher on DAY10 than on DAY5. All these parameters were found to be decreased after 10 days of hindlimb unloading, indicating the possible involvement of angiogenesis in bone repair impairment caused by reduced mechanical stimuli. In conclusion, the combined technique of sSRCT and ZrCA vascular casting is suitable for quantitative 3D imaging of angiogenesis and its surrounding bone regeneration. This method will be useful for better understanding the linkage between angiogenesis and bone repair.

Vector-averaged gravity-induced changes in cell signaling and vitamin D receptor activity in MG-63 cells are reversed by a 1,25-(OH)2D3 analog, EB1089

NASA Technical Reports Server (NTRS)

Narayanan, R.; Smith, C. L.; Weigel, N. L.

2002-01-01

Skeletal unloading in an animal hindlimb suspension model and microgravity experienced by astronauts or as a result of prolonged bed rest causes site-specific losses in bone mineral density of 1%-2% per month. This is accompanied by reductions in circulating levels of 1,25-(OH)(2)D(3), the active metabolite of vitamin D. 1,25-(OH)(2)D(3), the ligand for the vitamin D receptor (VDR), is important for calcium absorption and plays a role in differentiation of osteoblasts and osteoclasts. To examine the responses of cells to activators of the VDR in a simulated microgravity environment, we used slow-turning lateral vessels (STLVs) in a rotating cell culture system. We found that, similar to cells grown in microgravity, MG-63 cells grown in the STLVs produce less osteocalcin, alkaline phosphatase, and collagen Ialpha1 mRNA and are less responsive to 1,25-(OH)(2)D(3). In addition, expression of VDR was reduced. Moreover, growth in the STLV caused activation of the stress-activated protein kinase pathway (SAPK), a kinase that inhibits VDR activity. In contrast, the 1,25-(OH)(2)D(3) analog, EB1089, was able to compensate for some of the STLV-associated responses by reducing SAPK activity, elevating VDR levels, and increasing expression of osteocalcin and alkaline phosphatase. These studies suggest that, not only does simulated microgravity reduce differentiation of MG-63 cells, but the activity of the VDR, an important regulator of bone metabolism, is reduced. Use of potent, less calcemic analogs of 1,25-(OH)(2)D(3) may aid in overcoming this defect. Copyright 2002 Elsevier Science Inc.

Emodin suppresses cadmium-induced osteoporosis by inhibiting osteoclast formation.

PubMed

Chen, Xiao; Ren, Shuai; Zhu, Guoying; Wang, Zhongqiu; Wen, Xiaolin

2017-09-01

Environmental level of cadmium (Cd) exposure can induce bone loss. Emodin, a naturally compound found in Asian herbal medicines, could influence osteoblast/osteoclast differentiation. However, the effects of emodin on Cd-induced bone damage are not clarified. The aim of this study was to investigate the role of emodin on Cd-induced osteoporosis. Sprague-Dawley male rats were divided into three groups which were given 0mg/L, 50mg Cd/L and 50mg Cd/L plus emodin (50mg/kg body weight). Bone histological investigation, microCT analysis, metabolic biomarker determination and immunohistochemical staining were performed at the 12th week. The bone mass and bone microstructure index of rats treated with Cd were obviously lower than in control. Cd markedly enhanced the osteoclast formation compared with control. Emodin significantly abolished the Cd-induced bone microstructure damage (p<0.05), osteoclast formation and increase of tartrate-resistant acid phosphatase 5b level (p<0.05). Our data further showed that emodin attenuated the Cd-induced inhibition of osteoprotegerin expression and stimulation of receptor activator for nuclear factor-κ B ligand expression. Our data show that emodin suppresses the Cd-induced osteoporosis by inhibiting osteoclast formation. Copyright © 2017 Elsevier B.V. All rights reserved.

Requirement of the inducible nitric oxide synthase pathway for IL-1-induced osteoclastic bone resorption

PubMed Central

van't Hof, R. J.; Armour, K. J.; Smith, L. M.; Armour, K. E.; Wei, X. Q.; Liew, F. Y.; Ralston, S. H.

2000-01-01

Nitric oxide has been suggested to be involved in the regulation of bone turnover, especially in pathological conditions characterized by release of bone-resorbing cytokines. The cytokine IL-1 is thought to act as a mediator of periarticular bone loss and tissue damage in inflammatory diseases such as rheumatoid arthritis. IL-1 is a potent stimulator of both osteoclastic bone resorption and expression of inducible nitric oxide synthase (iNOS) in bone cells and other cell types. In this study, we investigated the role that the iNOS pathway plays in mediating the bone-resorbing effects of IL-1 by studying mice with targeted disruption of the iNOS gene. Studies in vitro and in vivo showed that iNOS-deficient mice exhibited profound defects of IL-1-induced osteoclastic bone resorption but responded normally to calciotropic hormones such as 1,25 dihydroxyvitamin D3 and parathyroid hormone. Immunohistochemical studies and electrophoretic mobility shift assays performed on bone marrow cocultures from iNOS-deficient mice showed abnormalities in IL-1-induced nuclear translocation of the p65 component of NFκB and in NFκB-DNA binding, which were reversed by treatment with the NO donor S-nitroso-acetyl penicillamine. These results show that the iNOS pathway is essential for IL-1-induced bone resorption and suggest that the effects of NO may be mediated by modulating IL-1-induced nuclear activation of NFκB in osteoclast precursors. PMID:10869429

Dynamic acoustic radiation force retains bone structural and mechanical integrity in a functional disuse osteopenia model.

PubMed

Uddin, Sardar M Z; Qin, Yi-Xian

2015-06-01

Disuse osteopenia and bone loss have been extensively reported in long duration space mission and long term bed rest. The pathology of the bone loss is similar to osteoporosis but highly confined to weight bearing bones. The current anabolic and/or anti-resorptive drugs have systemic effects and are costly over extended time, with concerns of long term fracture risk. This study use Low Intensity Pulsed Ultrasound (LIPUS) as a non-invasive acoustic force and anabolic stimulus to countermeasure disuse induced bone loss. Four-month old C57BL/6 mice were randomized into five groups, 1) age-matched (AM), 2) non-suspended sham (NS), 3) non-suspended-LIPUS (NU), 4) suspended sham (SS), and 5) suspended-LIPUS (SU) groups. After four weeks of suspension, μCT analyses showed significant decreases in trabecular bone volume fraction (BV/TV) (-36%, p<0.005), bone tissue mineral density (TMD) (-3%, p<0.05), trabecular thickness (Tb.Th) (-12.5%, p<0.005), and increase in bone surface/bone volume (+BS/BV) (+16%, p<0.005), relative to age-matched (AM). The application of LIPUS for 20 min/day for 5 days/week, significantly increased TMD (+3%, p<0.05), Tb.Th (+6%, p<0.05), and decreased BS/BV (-10%, p<0.005), relative to suspension alone (SS) mice. Histomorphometry analyses showed a breakdown of bone microstructure under disuse conditions consist with μCT results. In comparison to SS mice, LIPUS treated bone showed increased structural integrity with increased bone formation rates at metaphysical endosteal and trabecular surfaces (+0.104±0.07 vs 0.031±0.30 μm(3)/μm(2)/day) relative to SS. Four-point bending mechanical tests of disused SS femurs showed reduced elastic modulus (-53%, p<0.05), yield (-33%, p<0.05) and ultimate strength (-45%, p<0.05) at the femoral diaphysis relative to AM bone. LIPUS stimulation mitigated the adverse effects of disuse on bone elastic modulus (+42%, p<0.05), yield strength (+29%, p<0.05), and ultimate strength (+39%, p<0.05) relative to SS femurs. LIPUS provides the essential mechanical stimulus to retain bone morphological and mechanical integrity in disuse conditions. This study demonstrates LIPUS potential as regional therapeutic agent to countermeasure disuse induced bone loss while maintaining bone's integrity. Copyright © 2015 Elsevier Inc. All rights reserved.

Evidence for a pathogenic role of nitric oxide in inflammation-induced osteoporosis.

PubMed

Armour, K E; Van'T Hof, R J; Grabowski, P S; Reid, D M; Ralston, S H

1999-12-01

Inflammatory disease is associated with increased production of nitric oxide (NO) and activation of the inducible nitric oxide synthase (iNOS) pathway. Several studies have addressed the role of NO as a mediator of cytokine effects on bone cell activity in vitro. Stimulatory and inhibitory actions have been found, however, depending on the concentrations produced and model system used. In view of this, it has been difficult to predict whether increased production of NO during inflammation is likely to increase bone loss or prevent it. We have investigated the pathogenic role of NO in an animal model of inflammation-induced osteoporosis (IMO). NO production was increased in IMO when compared with controls (+344%; p < 0.01), and this was accompanied by activation of inducible NOS (iNOS) in the bone marrow space. Bone mineral density (BMD) was reduced in IMO when compared with controls (-64%; p < 0.01), and this was found to be associated with reduced osteoblast numbers (-44%; p < 0.05) and increased osteoclast numbers (+38%; p < 0.01). The NOS inhibitor L-NMMA reversed the deleterious effects of IMO on bone mass and bone turnover, but L-NMMA had no effect on bone mass in control animals. This study has important implications for many inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease which are associated with increased NO production and osteoporosis. Our data not only suggest that iNOS activation and increased NO production contribute to the pathogenesis of osteoporosis in these situations, but also suggest that NOS inhibitors could be of therapeutic value in the prevention and treatment of such bone loss.

The hemoglobin receptor protein of porphyromonas gingivalis inhibits receptor activator NF-kappaB ligand-induced osteoclastogenesis from bone marrow macrophages.

PubMed

Fujimura, Yuji; Hotokezaka, Hitoshi; Ohara, Naoya; Naito, Mariko; Sakai, Eiko; Yoshimura, Mamiko; Narita, Yuka; Kitaura, Hideki; Yoshida, Noriaki; Nakayama, Koji

2006-05-01

Extracellular proteinaceous factors of Porphyromonas gingivalis, a periodontal pathogen, that influence receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL)-induced osteoclastogenesis from bone marrow macrophages were investigated. The culture supernatant of P. gingivalis had the ability to inhibit RANKL-induced in vitro osteoclastogenesis. A major protein of the culture supernatant, hemoglobin receptor protein (HbR), suppressed RANKL-induced osteoclastogenesis in a dose-dependent fashion. HbR markedly inhibited RANKL-induced osteoclastogenesis when present in the culture for the first 24 h after addition of RANKL, whereas no significant inhibition was observed when HbR was added after 24 h or later, implying that HbR might interfere with only the initial stage of RANKL-mediated differentiation. HbR tightly bound to bone marrow macrophages and had the ability to induce phosphorylation of ERK, p38, NF-kappaB, and Akt. RANKL-induced phosphorylation of ERK, p38, and NF-kappaB was not suppressed by HbR, but that of Akt was markedly suppressed. HbR inhibited RANKL-mediated induction of c-Fos and NFATc1. HbR could induce beta interferon (IFN-beta) from bone marrow macrophages, but the induction level of IFN-beta might not be sufficient to suppress RANKL-mediated osteoclastogenesis, implying presence of an IFN-beta-independent pathway in HbR-mediated inhibition of osteoclastogenesis. Since rapid and extensive destruction of the alveolar bone causes tooth loss, resulting in loss of the gingival crevice that is an anatomical niche for periodontal pathogens such as P. gingivalis, the suppressive effect of HbR on osteoclastogenesis may help the microorganism exist long in the niche.

Carotid baroreceptor influence on forearm vascular resistance during low level lower body negative pressure

NASA Technical Reports Server (NTRS)

Thompson, Cynthia A.; Ludwig, David A.; Convertino, Victor A.

1991-01-01

The degree of forearm vasoconstriction induced by low levels of lower body negative pressure (LBNP) provides a measure of the responsiveness of the cardiopulmonary baroreflex. The validity of this measurement is based on the assumption that this vasoconstriction response is not influenced by unloading of carotid baroreceptors. To test the hypothesis that arterial baroreceptor unloading does not alter the degree of forearm vascular resistance during low levels of LBNP, 12 subjects were exposed to -15 and -20 mm Hg LBNP with and without additional artificial (+ 10 mm Hg neck pressure) unloading of the carotid baroreceptors. There was no measurable influence of carotid unloading on forearm vascular resistance at either level of LBNP. It is concluded that forearm vascular resistance measured during cardiopulmonary baroreceptor unloading is unaffected by carotid baroreceptor unloading within the magnitude encountered during low levels of LBNP.

TRAF family member-associated NF-κB activator (TANK) is a negative regulator of osteoclastogenesis and bone formation.

PubMed

Maruyama, Kenta; Kawagoe, Tatsukata; Kondo, Takeshi; Akira, Shizuo; Takeuchi, Osamu

2012-08-17

The differentiation of bone-resorbing osteoclasts is induced by RANKL signaling, and leads to the activation of NF-κB via TRAF6 activation. TRAF family member-associated NF-κB activator (TANK) acts as a negative regulator of Toll-like receptors (TLRs) and B-cell receptor (BCR) signaling by inhibiting TRAF6 activation. Tank(-/-) mice spontaneously develop autoimmune glomerular nephritis in an IL-6-dependent manner. Despite its importance in the TCRs and BCR-activated TRAF6 inhibition, the involvement of TANK in RANKL signaling is poorly understood. Here, we report that TANK is a negative regulator of osteoclast differentiation. The expression levels of TANK mRNA and protein were up-regulated during RANKL-induced osteoclastogenesis, and overexpression of TANK in vitro led to a decrease in osteoclast formation. The in vitro osteoclastogenesis of Tank(-/-) cells was significantly increased, accompanied by increased ubiquitination of TRAF6 and enhanced canonical NF-κB activation in response to RANKL stimulation. Tank(-/-) mice showed severe trabecular bone loss, but increased cortical bone mineral density, because of enhanced bone erosion and formation. TANK mRNA expression was induced during osteoblast differentiation and Tank(-/-) osteoblasts exhibited enhaced NF-κB activation, IL-11 expression, and bone nodule formation than wild-type control cells. Finally, wild-type mice transplanted with bone marrow cells from Tank(-/-) mice showed trabecular bone loss analogous to that in Tank(-/-) mice. These findings demonstrate that TANK is critical for osteoclastogenesis by regulating NF-κB, and is also important for proper bone remodeling.

TRAF Family Member-associated NF-κB Activator (TANK) Is a Negative Regulator of Osteoclastogenesis and Bone Formation*

PubMed Central

Maruyama, Kenta; Kawagoe, Tatsukata; Kondo, Takeshi; Akira, Shizuo; Takeuchi, Osamu

2012-01-01

The differentiation of bone-resorbing osteoclasts is induced by RANKL signaling, and leads to the activation of NF-κB via TRAF6 activation. TRAF family member-associated NF-κB activator (TANK) acts as a negative regulator of Toll-like receptors (TLRs) and B-cell receptor (BCR) signaling by inhibiting TRAF6 activation. Tank−/− mice spontaneously develop autoimmune glomerular nephritis in an IL-6-dependent manner. Despite its importance in the TCRs and BCR-activated TRAF6 inhibition, the involvement of TANK in RANKL signaling is poorly understood. Here, we report that TANK is a negative regulator of osteoclast differentiation. The expression levels of TANK mRNA and protein were up-regulated during RANKL-induced osteoclastogenesis, and overexpression of TANK in vitro led to a decrease in osteoclast formation. The in vitro osteoclastogenesis of Tank−/− cells was significantly increased, accompanied by increased ubiquitination of TRAF6 and enhanced canonical NF-κB activation in response to RANKL stimulation. Tank−/− mice showed severe trabecular bone loss, but increased cortical bone mineral density, because of enhanced bone erosion and formation. TANK mRNA expression was induced during osteoblast differentiation and Tank−/− osteoblasts exhibited enhaced NF-κB activation, IL-11 expression, and bone nodule formation than wild-type control cells. Finally, wild-type mice transplanted with bone marrow cells from Tank−/− mice showed trabecular bone loss analogous to that in Tank−/− mice. These findings demonstrate that TANK is critical for osteoclastogenesis by regulating NF-κB, and is also important for proper bone remodeling. PMID:22773835

A Chemically Modified Curcumin (CMC 2.24) Inhibits Nuclear Factor κB Activation and Inflammatory Bone Loss in Murine Models of LPS-Induced Experimental Periodontitis and Diabetes-Associated Natural Periodontitis.

PubMed

Elburki, Muna S; Rossa, Carlos; Guimarães-Stabili, Morgana R; Lee, Hsi-Ming; Curylofo-Zotti, Fabiana A; Johnson, Francis; Golub, Lorne M

2017-08-01

The purpose of this study was to assess the effect of a novel chemically modified curcumin (CMC 2.24) on NF-κB and MAPK signaling and inflammatory cytokine production in two experimental models of periodontal disease in rats. Experimental model I: Periodontitis was induced by repeated injections of LPS into the gingiva (3×/week, 3 weeks); control rats received vehicle injections. CMC 2.24, or the vehicle, was administered by daily oral gavage for 4 weeks. Experimental model II: Diabetes was induced in adult male rats by streptozotocin injection; periodontal breakdown then results as a complication of uncontrolled hyperglycemia. Non-diabetic rats served as controls. CMC 2.24, or the vehicle, was administered by oral gavage daily for 3 weeks to the diabetics. Hemimaxillae and gingival tissues were harvested, and bone loss was assessed radiographically. Gingival tissues were pooled according to the experimental conditions and processed for the analysis of matrix metalloproteinases (MMPs) and bone-resorptive cytokines. Activation of p38 MAPK and NF-κB signaling pathways was assessed by western blot. Both LPS and diabetes induced an inflammatory process in the gingival tissues associated with excessive alveolar bone resorption and increased activation of p65 (NF-κB) and p38 MAPK. In both models, the administration of CMC 2.24 produced a marked reduction of inflammatory cytokines and MMPs in the gingival tissues, decreased bone loss, and decreased activation of p65 (NF-κB) and p38 MAPK. Inhibition of these cell signaling pathways by this novel tri-ketonic curcuminoid (natural curcumin is di-ketonic) may play a role in its therapeutic efficacy in locally and systemically associated periodontitis.

Mitigating HZE Radiation-Induced Deficits in Marrow-Derived Mesenchymal Progenitor Cells and Skeletal Structure

NASA Technical Reports Server (NTRS)

Globus, Ruth K.; Schreurs, Ann-Sofie; Shirazi-Fard, Yasaman; Terada, Masahiro; Alwood, Joshua; Halloran, Bernard; Tahimic, Candice

2016-01-01

Future long-duration space exploration beyond the earths magnetosphere will increase human exposure to space radiation and associated risks to skeletal health. We hypothesize that oxidative stress resulting from radiation exposure causes progressive bone loss and dysfunction in associated tissue. In animal studies, increased free radical formation is associated with pathological changes in bone structure, enhanced bone resorption, reduced bone formation and decreased bone mineral density, which can lead to skeletal fragility.

Structural and functional remodeling of skeletal muscle microvasculature is induced by simulated microgravity

NASA Technical Reports Server (NTRS)

Delp, M. D.; Colleran, P. N.; Wilkerson, M. K.; McCurdy, M. R.; Muller-Delp, J.

2000-01-01

Hindlimb unloading of rats results in a diminished ability of skeletal muscle arterioles to constrict in vitro and elevate vascular resistance in vivo. The purpose of the present study was to determine whether alterations in the mechanical environment (i.e., reduced fluid pressure and blood flow) of the vasculature in hindlimb skeletal muscles from 2-wk hindlimb-unloaded (HU) rats induces a structural remodeling of arterial microvessels that may account for these observations. Transverse cross sections were used to determine media cross-sectional area (CSA), wall thickness, outer perimeter, number of media nuclei, and vessel luminal diameter of feed arteries and first-order (1A) arterioles from soleus and the superficial portion of gastrocnemius muscles. Endothelium-dependent dilation (ACh) was also determined. Media CSA of resistance arteries was diminished by hindlimb unloading as a result of decreased media thickness (gastrocnemius muscle) or reduced vessel diameter (soleus muscle). ACh-induced dilation was diminished by 2 wk of hindlimb unloading in soleus 1A arterioles, but not in gastrocnemius 1A arterioles. These results indicate that structural remodeling and functional adaptations of the arterial microvasculature occur in skeletal muscles of the HU rat; the data suggest that these alterations may be induced by reductions in transmural pressure (gastrocnemius muscle) and wall shear stress (soleus muscle).

First interactions between hydrogen and stress-induced reverse transformation of Ni-Ti superelastic alloy

NASA Astrophysics Data System (ADS)

Yokoyama, Ken'ichi; Hashimoto, Tatsuki; Sakai, Jun'ichi

2017-11-01

The first dynamic interactions between hydrogen and the stress-induced reverse transformation have been investigated by performing an unloading test on a Ni-Ti superelastic alloy subjected to hydrogen charging under a constant applied strain in the elastic deformation region of the martensite phase. Upon unloading the specimen, charged with a small amount of hydrogen, no change in the behaviour of the stress-induced reverse transformation is observed in the stress-strain curve, although the behaviour of the stress-induced martensite transformation changes. With increasing amount of hydrogen charging, the critical stress for the reverse transformation markedly decreases. Eventually, for a larger amount of hydrogen charging, the reverse transformation does not occur, i.e. there is no recovery of the superelastic strain. The residual martensite phase on the side surface of the unloaded specimen is confirmed by X-ray diffraction. Upon training before the unloading test, the properties of the reverse transformation slightly recover after ageing in air at room temperature. The present study indicates that to change the behaviour of the reverse transformation a larger amount of hydrogen than that for the martensite transformation is necessary. In addition, it is likely that a substantial amount of hydrogen in solid solution more strongly suppresses the reverse transformation than hydrogen trapped at defects, thereby stabilising the martensite phase.

Changes in markers of bone formation and resorption in a bed rest model of weightlessness

NASA Technical Reports Server (NTRS)

Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

1993-01-01

To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

OSTEOCYTE APOPTOSIS

PubMed Central

Jilka, Robert L.; Noble, Brendon; Weinstein, Robert S.

2012-01-01

Apoptotic death of osteocytes was recognized over 15 years ago, but its significance for bone homeostasis has remained elusive. A new paradigm has emerged that invokes osteocyte apoptosis as a critical event in the recruitment of osteoclasts to a specific site in response to skeletal unloading, fatigue damage, estrogen deficiency and perhaps in other states where bone must be removed. This is accomplished by yet to be defined signals emanating from dying osteocytes, which stimulate neighboring viable osteocytes to produce osteoclastogenic cytokines. The osteocyte apoptosis caused by chronic glucocorticoid administration does not increase osteoclasts; however, it does negatively impact maintenance of bone hydration, vascularity, and strength. PMID:23238124

Mechanical Loading Attenuates Radiation-Induced Bone Loss in Bone Marrow Transplanted Mice.

PubMed

Govey, Peter M; Zhang, Yue; Donahue, Henry J

2016-01-01

Exposure of bone to ionizing radiation, as occurs during radiotherapy for some localized malignancies and blood or bone marrow cancers, as well as during space travel, incites dose-dependent bone morbidity and increased fracture risk. Rapid trabecular and endosteal bone loss reflects acutely increased osteoclastic resorption as well as decreased bone formation due to depletion of osteoprogenitors. Because of this dysregulation of bone turnover, bone's capacity to respond to a mechanical loading stimulus in the aftermath of irradiation is unknown. We employed a mouse model of total body irradiation and bone marrow transplantation simulating treatment of hematologic cancers, hypothesizing that compression loading would attenuate bone loss. Furthermore, we hypothesized that loading would upregulate donor cell presence in loaded tibias due to increased engraftment and proliferation. We lethally irradiated 16 female C57Bl/6J mice at age 16 wks with 10.75 Gy, then IV-injected 20 million GFP(+) total bone marrow cells. That same day, we initiated 3 wks compression loading (1200 cycles 5x/wk, 10 N) in the right tibia of 10 of these mice while 6 mice were irradiated, non-mechanically-loaded controls. As anticipated, before-and-after microCT scans demonstrated loss of trabecular bone (-48.2% Tb.BV/TV) and cortical thickness (-8.3%) at 3 wks following irradiation. However, loaded bones lost 31% less Tb.BV/TV and 8% less cortical thickness (both p<0.001). Loaded bones also had significant increases in trabecular thickness and tissue mineral densities from baseline. Mechanical loading did not affect donor cell engraftment. Importantly, these results demonstrate that both cortical and trabecular bone exposed to high-dose therapeutic radiation remain capable of an anabolic response to mechanical loading. These findings inform our management of bone health in cases of radiation exposure.

What is the impact of immunosuppressive treatment on the post-transplant renal osteopathy?

PubMed

Blaslov, Kristina; Katalinic, Lea; Kes, Petar; Spasovski, Goce; Smalcelj, Ruzica; Basic-Jukic, Nikolina

2014-05-01

Although glucocorticoid therapy is considered to be the main pathogenic factor, a consistent body of evidence suggests that other immunosuppressants might also play an important role in the development of the post-transplant renal osteopathy (PRO) through their pleiotropic pharmacological effects. Glucocorticoids seem to induce osteoclasts' activity suppressing the osteoblasts while data regarding other immunosuppressive drugs are still controversial. Mycophenolate mofetil and azathioprine appear to be neutral regarding the bone metabolism. However, the study analyzing any independent effect of antimetabolites on bone turnover has not been conducted yet. Calcineurin inhibitors (CNIs) induce trabecular bone loss in rodent, with contradictory results in renal transplant recipients. Suppression of vitamin D receptor is probably the underlying mechanism of renal calcium wasting in renal transplant recipients receiving CNI. In spite of an increased 1,25(OH)2 vitamin D level, the kidney is not able to reserve calcium, suggesting a role of vitamin D resistance that may be related to bone loss. More efforts should be invested to determine the role of CNI in PRO. In particular, data regarding the role of mammalian target of rapamycin inhibitors (mTORi), such as sirolimus and everolimus, in the PRO development are still controversial. Rapamycin markedly decreases bone longitudinal growth as well as callus formation in experimental models, but also lowers the rate of bone resorption markers and glomerular filtration in clinical studies. Everolimus potently inhibits primary mouse and human osteoclast activity as well as the osteoclast differentiation. It also prevents the ovariectomy-induced loss of cancellous bone by 60 %, an effect predominantly associated with a decreased osteoclast-mediated bone resorption, resulting in a partial preservation of the cancellous bone. At present, there is no clinical study analyzing the effect of everolimus on bone turnover in renal transplant recipients or comparing sirolimus versus everolimus impact on bone, so only general conclusions could be drawn. Hence, the use of mTORi might be useful in patients with PRO due to their possible potential to inhibit osteoclast activity which might lead to a decreased rate of bone resorption. In addition, it should be also emphasized that they might inhibit osteoblast activity which may lead to a decreased bone formation and adynamic bone disease. Further studies are urgently needed to solve these important clinical dilemmas.

Rapidly Assessing Changes in Bone Mineral Balance Using Natural Stable Calcium Isotopes

NASA Technical Reports Server (NTRS)

Morgan, J. L. L.; Gordon, G. W.; Romaniello, S. J.; Skulan, J. L.; Smith, S. M.; Anbar, A. D.

2011-01-01

We demonstrate that variations in the Ca isotope ratios in urine rapidly and quantitatively reflect changes in bone mineral balance. This variation occurs because bone formation depletes soft tissue of light Ca isotopes, while bone resorption releases that isotopically light Ca back into soft tissue. In a study of 12 individuals confined to bed rest, a condition known to induce bone resorption, we show that Ca isotope ratios shift in a direction consistent with net bone loss after just 7 days, long before detectible changes in bone density occur. Consistent with this interpretation, the Ca isotope variations track changes observed in N-teleopeptide, a bone resorption biomarker, while bone-specific alkaline phosphatase, a bone formation biomarker, is unchanged. Ca isotopes can in principle be used to quantify net changes in bone mass. Ca isotopes indicate an average loss of 0.62 +/- 0.16 % in bone mass over the course of this 30-day study. The Ca isotope technique should accelerate the pace of discovery of new treatments for bone disease and provide novel insights into the dynamics of bone metabolism.

INF-γ encoding plasmid administration triggers bone loss and disrupts bone marrow microenvironment.

PubMed

Agas, Dimitrios; Gusmão Silva, Guilherme; Laus, Fulvio; Marchegiani, Andrea; Capitani, Melania; Vullo, Cecilia; Catone, Giuseppe; Lacava, Giovanna; Concetti, Antonio; Marchetti, Luigi; Sabbieti, Maria Giovanna

2017-02-01

IFN-γ is a pleotropic cytokine produced in the bone microenvironment. Although IFN-γ is known to play a critical role on bone remodeling, its function is not fully elucidated. Consistently, outcomes on the effects of IFN-γ recombinant protein on bone loss are contradictory among reports. In our work we explored, for the first time, the role of IFN-γ encoding plasmid (pIFN-γ) in a mouse model of osteopenia induced by ovariectomy and in the sham-operated counterpart to estimate its effects in skeletal homeostasis. Ovariectomy produced a dramatic decrease of bone mineral density (BMD). pINF-γ injected mice showed a pathologic bone and bone marrow phenotype; the disrupted cortical and trabecular bone microarchitecture was accompanied by an increased release of pro-inflammatory cytokine by bone marrow cells. Moreover, mesenchymal stem cells' (MSCs) commitment to osteoblast was found impaired, as evidenced by the decline of osterix-positive (Osx + ) cells within the mid-diaphyseal area of femurs. For instance, a reduction and redistribution of CXCL12 cells have been found, in accordance with bone marrow morphological alterations. As similar effects were observed both in sham-operated and in ovariectomized mice, our studies proved that an increased IFN-γ synthesis in bone marrow might be sufficient to induce inflammatory and catabolic responses even in the absence of pathologic predisposing substrates. In addition, the obtained data might raise questions about pIFN-γ's safety when it is used as vaccine adjuvant. © 2017 Society for Endocrinology.

Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog

PubMed Central

Martinez, Arturo; Guitián, Francisco; López-Píriz, Roberto; Bartolomé, José F.; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S.

2014-01-01

The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression. PMID:24466292

Comparison of bone density in amenorrheic women due to athletics, weight loss, and premature menopause.

PubMed

Jones, K P; Ravnikar, V A; Tulchinsky, D; Schiff, I

1985-07-01

Studied was the peripheral bone density of 39 women (ages 18 to 43) with the diagnosis of secondary amenorrhea in an effort to define the population of amenorrheic women at risk for osteoporosis. Eight women had exercise-induced amenorrhea (athletes), 20 women had amenorrhea associated with weight loss, and 11 women had premature menopause. These diagnoses were made on the basis of history, physical examination, and luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin levels, and failure to have withdrawal bleeding after the administration of progestin. Twenty-five nonathletic, normally menstruating women served as control subjects. The peripheral bone density of the amenorrheic athletes (0.738 g/cm2 +/- 0.047) was not significantly different from that of the controls (0.726 g/cm2 +/- 0.044). The average bone density of the group with weight loss-associated amenorrhea (0.672 g/cm2 +/- 0.066) was significantly less than controls (P less than .005) as was that of the women with premature menopause (0.616 g/cm2 +/- 0.048, P less than .001). There was a significant correlation between months of amenorrhea and decrease in bone density (r = 0.506, P less than .001). From this study it was concluded that women with exercise-associated amenorrhea are not at significant risk for cortical bone loss as measured by direct photon absorptiometry. Women with weight loss-associated amenorrhea and women with premature menopause are at significant risk for bone loss when compared with normal controls.

The histopathological and morphometric investigation of the effects of systemically administered boric acid on alveolar bone loss in ligature-induced periodontitis in diabetic rats.

PubMed

Balci Yuce, Hatice; Toker, Hulya; Goze, Fahrettin

2014-11-01

The purpose of this study was to evaluate the effects of systemically administered boric acid on alveolar bone loss, histopathological changes and oxidant/antioxidant status in ligature-induced periodontitis in diabetic rats. Forty-four Wistar rats were divided into six experimental groups: (1) non-ligated (NL, n = 6) group, (2) ligature only (LO, n = 6) group, (3) Streptozotocin only (STZ, n = 8) group, (4) STZ and ligature (STZ+LO, n = 8) group, (5) STZ, ligature and systemic administration of 15 mg/kg/day boric acid for 15 days (BA15, n = 8) group and (6) STZ, ligature and systemic administration of 30 mg/kg/day boric acid for 15 days (BA30, n = 8) group. Diabetes mellitus was induced by 60 mg/kg streptozotocin. Silk ligatures were placed at the gingival margin of lower first molars of the mandibular quadrant. The study duration was 15 days after diabetes induction and the animals were sacrificed at the end of this period. Changes in alveolar bone levels were clinically measured and tissues were histopathologically examined. Serum total antioxidant status (TAS), total oxidant status (TOS), calcium (Ca) and magnesium (Mg) levels and oxidative stress index (OSI) were evaluated. Primary outcome was alveolar bone loss. Seconder outcome (osteoblast number) was also measured. At the end of 15 days, the alveolar bone loss was significantly higher in the STZ+LO group compared to the other groups (p < 0.05). There was no significant difference in alveolar bone loss between the STZ+LO 15 mg/kg boric acid and STZ+LO 30 mg/kg boric acid groups (p > 0.05). Systemically administered boric acid significantly decreased alveolar bone loss compared to the STZ+LO group (p < 0.05). The osteoblast number in the BA30 group was significantly higher than those of the NL, STZ and STZ+LO groups (p < 0.05). Inflammatory cell infiltration was significantly higher in the STZ+LO group the other groups (p < 0.05). Serum TAS levels were significantly higher in the NL and LO groups than the other groups (p < 0.05). The differences in TOS levels were not found to be significant among all the groups (p > 0.05). The OSI values of the BA30 group were significantly lower than the STZ+LO group (p < 0.05). Also, the differences in serum calcium and magnesium levels were insignificant among the all groups (p > 0.05). Within the limits of this study, it can be suggested that BA, when administered systemically, may reduce alveolar bone loss in the diabetic rat model.

Molecular stress-inducing compounds increase osteoclast formation in a heat shock factor 1 protein-dependent manner.

PubMed

Chai, Ryan C; Kouspou, Michelle M; Lang, Benjamin J; Nguyen, Chau H; van der Kraan, A Gabrielle J; Vieusseux, Jessica L; Lim, Reece C; Gillespie, Matthew T; Benjamin, Ivor J; Quinn, Julian M W; Price, John T

2014-05-09

Many anticancer therapeutic agents cause bone loss, which increases the risk of fractures that severely reduce quality of life. Thus, in drug development, it is critical to identify and understand such effects. Anticancer therapeutic and HSP90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) causes bone loss by increasing osteoclast formation, but the mechanism underlying this is not understood. 17-AAG activates heat shock factor 1 (Hsf1), the master transcriptional regulator of heat shock/cell stress responses, which may be involved in this negative action of 17-AAG upon bone. Using mouse bone marrow and RAW264.7 osteoclast differentiation models we found that HSP90 inhibitors that induced a heat shock response also enhanced osteoclast formation, whereas HSP90 inhibitors that did not (including coumermycin A1 and novobiocin) did not affect osteoclast formation. Pharmacological inhibition or shRNAmir knockdown of Hsf1 in RAW264.7 cells as well as the use of Hsf1 null mouse bone marrow cells demonstrated that 17-AAG-enhanced osteoclast formation was Hsf1-dependent. Moreover, ectopic overexpression of Hsf1 enhanced 17-AAG effects upon osteoclast formation. Consistent with these findings, protein levels of the essential osteoclast transcription factor microphthalmia-associated transcription factor were increased by 17-AAG in an Hsf1-dependent manner. In addition to HSP90 inhibitors, we also identified that other agents that induced cellular stress, such as ethanol, doxorubicin, and methotrexate, also directly increased osteoclast formation, potentially in an Hsf1-dependent manner. These results, therefore, indicate that cellular stress can enhance osteoclast differentiation via Hsf1-dependent mechanisms and may significantly contribute to pathological and therapeutic related bone loss.

Molecular events underlying skeletal muscle atrophy and the development of effective countermeasures

NASA Technical Reports Server (NTRS)

Booth, F. W.; Criswell, D. S.

1997-01-01

Skeletal muscle adapts to loading; atrophying when exposed to unloading on Earth or in spaceflight. Significant atrophy (decreases in muscle fiber cross-section of 11-24%) in humans has been noted after only 5 days in space. Since muscle strength is determined both by muscle cross-section and synchronization of motor unit recruitment, a loss in muscle size weakens astronauts, which would increase risks to their safety if an emergency required maximal muscle force. Numerous countermeasures have been tested to prevent atrophy. Resistant exercise together with growth hormone and IGF-I are effective countermeasures to unloading as most atrophy is prevented in animal models. The loss of muscle protein is due to an early decrease in protein synthesis rate and a later increase in protein degradation. The initial decrease in protein synthesis is a result of decreased protein translation, caused by a prolongation in the elongation rate. A decrease in HSP70 by a sight increase in ATP may be the factors prolonging elongation rate. Increases in the activities of proteolytic enzymes and in ubiquitin contribute to the increased protein degradation rate in unloaded muscle. Numerous mRNA concentrations have been shown to be altered in unloaded muscles. Decreases in mRNAs for contractile proteins usually occur after the initial fall in protein synthesis rates. Much additional research is needed to determine the mechanism by which muscle senses the absence of gravity with an adaptive atrophy. The development of effective countermeasures to unloading atrophy will require more research.

Differences in responses to X-ray exposure between osteoclast and osteoblast cells

PubMed Central

Zhang, Jian; Wang, Ziyang; Wu, Anqing; Nie, Jing; Pei, Hailong; Hu, Wentao; Wang, Bing; Shang, Peng; Li, Bingyan

2017-01-01

Abstract Radiation-induced bone loss is a potential health concern for cancer patients undergoing radiotherapy. Enhanced bone resorption by osteoclasts and decreased bone formation by osteoblasts were thought to be the main reasons. In this study, we showed that both pre-differentiating and differentiating osteoclasts were relatively sensitive to X-rays compared with osteoblasts. X-rays decreased cell viability to a greater degree in RAW264.7 cells and in differentiating cells than than in osteoblastic MC3T3-E1 cells. X-rays at up to 8 Gy had little effects on osteoblast mineralization. In contrast, X-rays at 1 Gy induced enhanced osteoclastogenesis by enhanced cell fusion, but had no effects on bone resorption. A higher dose of X-rays at 8 Gy, however, had an inhibitory effect on bone resorption. In addition, actin ring formation was disrupted by 8 Gy of X-rays and reorganized into clusters. An increased activity of Caspase 3 was found after X-ray exposure. Actin disorganization and increased apoptosis may be the potential effects of X-rays at high doses, by inhibiting osteoclast differentiation. Taken together, our data indicate high radiosensitivity of osteoclasts. X-ray irradiation at relatively low doses can activate osteoclastogenesis, but not osteogenic differentiation. The radiosensitive osteoclasts are the potentially responsive cells for X-ray-induced bone loss. PMID:28541506

IGF-1 Regulates Vertebral Bone Aging Through Sex-Specific and Time-Dependent Mechanisms.

PubMed

Ashpole, Nicole M; Herron, Jacquelyn C; Mitschelen, Matthew C; Farley, Julie A; Logan, Sreemathi; Yan, Han; Ungvari, Zoltan; Hodges, Erik L; Csiszar, Anna; Ikeno, Yuji; Humphrey, Mary Beth; Sonntag, William E

2016-02-01

Advanced aging is associated with increased risk of bone fracture, especially within the vertebrae, which exhibit significant reductions in trabecular bone structure. Aging is also associated with a reduction in circulating levels of insulin-like growth factor (IGF-1). Studies have suggested that the reduction in IGF-1 compromises healthspan, whereas others report that loss of IGF-1 is beneficial because it increases healthspan and lifespan. To date, the effect of decreases in circulating IGF-1 on vertebral bone aging has not been thoroughly investigated. Here, we delineate the consequences of a loss of circulating IGF-1 on vertebral bone aging in male and female Igf(f/f) mice. IGF-1 was reduced at multiple specific time points during the mouse lifespan: early in postnatal development (crossing albumin-cyclic recombinase [Cre] mice with Igf(f/f) mice); and in early adulthood and in late adulthood using hepatic-specific viral vectors (AAV8-TBG-Cre). Vertebrae bone structure was analyzed at 27 months of age using micro-computed tomography (μCT) and quantitative bone histomorphometry. Consistent with previous studies, both male and female mice exhibited age-related reductions in vertebral bone structure. In male mice, reduction of circulating IGF-1 induced at any age did not diminish vertebral bone loss. Interestingly, early-life loss of IGF-1 in females resulted in a 67% increase in vertebral bone volume fraction, as well as increased connectivity density and increased trabecular number. The maintenance of bone structure in the early-life IGF-1-deficient females was associated with increased osteoblast surface and an increased ratio of osteoprotegerin/receptor-activator of NF-κB-ligand (RANKL) levels in circulation. Within 3 months of a loss of IGF-1, there was a 2.2-fold increase in insulin receptor expression within the vertebral bones of our female mice, suggesting that local signaling may compensate for the loss of circulating IGF-1. Together, these data suggest the age-related loss of vertebral bone density in females can be reduced by modifying circulating IGF-1 levels early in life. © 2015 American Society for Bone and Mineral Research.

Expression of a calpastatin transgene slows muscle wasting and obviates changes in myosin isoform expression during murine muscle disuse

PubMed Central

Tidball, James G; Spencer, Melissa J

2002-01-01

Muscle wasting is a prominent feature of several systemic diseases, neurological damage and muscle disuse. The contribution of calpain proteases to muscle wasting in any instance of muscle injury or disease has remained unknown because of the inability to specifically perturb calpain activity in vivo. We have generated a transgenic mouse with muscle-specific overexpression of calpastatin, which is the endogenous inhibitor of calpains, and induced muscle atrophy by unloading hindlimb musculature for 10 days. Expression of the transgene resulted in increases in calpastatin concentration in muscle by 30- to 50-fold, and eliminated all calpain activity that was detectable on zymograms. Muscle fibres in ambulatory, transgenic mice were smaller in diameter, but more numerous, so that muscle mass did not differ between transgenic and non-transgenic mice. This is consistent with the role of the calpain-calpastatin system in muscle cell fusion that has been observed in vitro. Overexpression of calpastatin reduced muscle atrophy by 30 % during the 10 day unloading period. In addition, calpastatin overexpression completely prevented the shift in myofibrillar myosin content from slow to fast isoforms, which normally occurs in muscle unloading. These findings indicate that therapeutics directed toward regulating the calpain-calpastatin system may be beneficial in preventing muscle mass loss in muscle injury and disease. PMID:12482888

MAPK Usage in Periodontal Disease Progression

PubMed Central

Li, Qiyan; Valerio, Michael S.; Kirkwood, Keith L.

2012-01-01

In periodontal disease, host recognition of bacterial constituents, including lipopolysaccharide (LPS), induces p38 MAPK activation and subsequent inflammatory cytokine expression, favoring osteoclastogenesis and increased net bone resorption in the local periodontal environment. In this paper, we discuss evidence that the p38/MAPK-activated protein kinase-2 (MK2) signaling axis is needed for periodontal disease progression: an orally administered p38α inhibitor reduced the progression of experimental periodontal bone loss by reducing inflammation and cytokine expression. Subsequently, the significance of p38 signaling was confirmed with RNA interference to attenuate MK2-reduced cytokine expression and LPS-induced alveolar bone loss. MAPK phosphatase-1 (MKP-1), a negative regulator of MAPK activation, was also critical for periodontal disease progression. In MPK-1-deficient mice, p38-sustained activation increased osteoclast formation and bone loss, whereas MKP-1 overexpression dampened p38 signaling and subsequent cytokine expression. Finally, overexpression of the p38/MK2 target RNA-binding tristetraprolin (TTP) decreased mRNA stability of key inflammatory cytokines at the posttranscriptional level, thereby protecting against periodontal inflammation. Collectively, these studies highlight the importance of p38 MAPK signaling in immune cytokine production and periodontal disease progression. PMID:22315682

Pre-existing periodontitis exacerbates experimental arthritis in a mouse model.

PubMed

Cantley, Melissa D; Haynes, David R; Marino, Victor; Bartold, P Mark

2011-06-01

Previous studies have shown a higher incidence of alveolar bone loss in patients with rheumatoid arthritis (RA) and that patients with periodontitis are at a greater risk of developing RA. The aim of this study was to develop an animal model to assess the relationship between pre-existing periodontitis and experimental arthritis (EA). Periodontitis was first induced in mice by oral gavage with Porphyromonas gingivalis followed by EA using the collagen antibody-induced arthritis model. These animals were compared with animals with periodontitis alone, EA alone and no disease (controls). Visual changes in paw swelling were assessed to determine clinical development of EA. Alveolar bone and joint changes were assessed using micro-CT, histological analyses and immunohistochemistry. Serum levels of C-reactive protein were used to monitor systemic inflammation. Mice with pre-existing periodontitis developed more severe arthritis, which developed at a faster rate. Mice with periodontitis only also showed evidence of loss of bone within the radiocarpal joint. There was also evidence of alveolar bone loss in mice with EA alone. The results of this study indicate that pre-existing periodontitis exacerbated experimental arthritis in a mouse model. © 2011 John Wiley & Sons A/S.

Icaritin requires Phosphatidylinositol 3 kinase (PI3K)/Akt signaling to counteract skeletal muscle atrophy following mechanical unloading

PubMed Central

ZHANG, Zong-Kang; LI, Jie; LIU, Jin; GUO, Baosheng; LEUNG, Albert; ZHANG, Ge; ZHANG, Bao-Ting

2016-01-01

Counteracting muscle atrophy induced by mechanical unloading/inactivity is of great clinical need and challenge. A therapeutic agent that could counteract muscle atrophy following mechanical unloading in safety is desired. This study showed that natural product Icaritin (ICT) could increase the phosphorylation level of Phosphatidylinositol 3 kinase (PI3K) at p110 catalytic subunit and promote PI3K/Akt signaling markers in C2C12 cells. This study further showed that the high dose ICT treatment could significantly attenuate the decreases in the phosphorylation level of PI3K at p110 catalytic subunit and its downstream markers related to protein synthesis, and inhibit the increases in protein degradation markers at mRNA and protein levels in rat soleus muscle following 28-day hindlimb unloading. In addition, the decreases in soleus muscle mass, muscle fiber cross-sectional area, twitch force, specific force, contraction time and half relaxation time could be significantly attenuated by the high dose ICT treatment. The low dose ICT treatment could moderately attenuate the above changes induced by unloading. Wortmannin, a specific inhibitor of PI3K at p110 catalytic subunit, could abolish the above effects of ICT in vitro and in vivo, indicating that PI3K/Akt signaling could be required by ICT to counteract skeletal muscle atrophy following mechanical unloading. PMID:26831566

Mechanical Loading Attenuates Radiation-Induced Bone Loss in Bone Marrow Transplanted Mice

PubMed Central

Govey, Peter M.; Zhang, Yue; Donahue, Henry J.

2016-01-01

Exposure of bone to ionizing radiation, as occurs during radiotherapy for some localized malignancies and blood or bone marrow cancers, as well as during space travel, incites dose-dependent bone morbidity and increased fracture risk. Rapid trabecular and endosteal bone loss reflects acutely increased osteoclastic resorption as well as decreased bone formation due to depletion of osteoprogenitors. Because of this dysregulation of bone turnover, bone’s capacity to respond to a mechanical loading stimulus in the aftermath of irradiation is unknown. We employed a mouse model of total body irradiation and bone marrow transplantation simulating treatment of hematologic cancers, hypothesizing that compression loading would attenuate bone loss. Furthermore, we hypothesized that loading would upregulate donor cell presence in loaded tibias due to increased engraftment and proliferation. We lethally irradiated 16 female C57Bl/6J mice at age 16 wks with 10.75 Gy, then IV-injected 20 million GFP(+) total bone marrow cells. That same day, we initiated 3 wks compression loading (1200 cycles 5x/wk, 10 N) in the right tibia of 10 of these mice while 6 mice were irradiated, non-mechanically-loaded controls. As anticipated, before-and-after microCT scans demonstrated loss of trabecular bone (-48.2% Tb.BV/TV) and cortical thickness (-8.3%) at 3 wks following irradiation. However, loaded bones lost 31% less Tb.BV/TV and 8% less cortical thickness (both p<0.001). Loaded bones also had significant increases in trabecular thickness and tissue mineral densities from baseline. Mechanical loading did not affect donor cell engraftment. Importantly, these results demonstrate that both cortical and trabecular bone exposed to high-dose therapeutic radiation remain capable of an anabolic response to mechanical loading. These findings inform our management of bone health in cases of radiation exposure. PMID:27936104

Effects of vitamin K2 on cortical and cancellous bone mass, cortical osteocyte and lacunar system, and porosity in sciatic neurectomized rats.

PubMed

Iwamoto, Jun; Matsumoto, Hideo; Takeda, Tsuyoshi; Sato, Yoshihiro; Yeh, James K

2010-09-01

The purpose of the present study was to examine the effects of vitamin K2 on cortical and cancellous bone mass, cortical osteocyte and lacunar system, and porosity in sciatic neurectomized rats. Thirty-four female Sprague-Dawley retired breeder rats were randomized into three groups: age-matched control, sciatic neurectomy (NX), and NX + vitamin K2 administration (menatetrenone, 30 mg/kg/day p.o., three times a week). At the end of the 8-week experiment, bone histomorphometric analysis was performed on cortical and cancellous bone of the tibial diaphysis and proximal metaphysis, respectively, and osteocyte lacunar system and porosity were evaluated on cortical bone of the tibial diaphysis. NX decreased cortical and cancellous bone mass compared with age-matched controls as a result of increased endocortical and trabecular bone erosion and decreased trabecular mineral apposition rate (MAR). Vitamin K2 ameliorated the NX-induced increase in bone erosion, prevented the NX-induced decrease in MAR, and increased bone formation rate (BFR/bone surface) in cancellous bone, resulting in an attenuation of NX-induced cancellous bone loss. However, vitamin K2 did not significantly influence cortical bone mass. NX also decreased osteocyte density and lacunar occupancy and increased porosity in cortical bone compared with age-matched controls. Vitamin K2 ameliorated the NX-induced decrease in lacunar occupancy by viable osteocytes and the NX-induced increase in porosity. The present study showed the efficacy of vitamin K2 for cancellous bone mass and cortical lacunar occupancy by viable osteocytes and porosity in sciatic NX rats.

Promotion of bone growth by dietary soy protein isolate: Comparision with dietary casein, whey hydrolysate and rice protein isolate in growing female rats

USDA-ARS?s Scientific Manuscript database

The effects of different dietary protein sources(casein (CAS), soy protein isolate (SPI), whey protein hydrolysate (WPH) and rice protein isolate (RPI)) on bone were studied in intact growing female rats and in ovarectomized (OVX) rats showing sex steroid deficiency-induced bone loss. In addition, S...

Green Tea Polyphenols and Vitamin D3 Protect Bone Microarchitecture in Female Rats with Chronic Inflammation

USDA-ARS?s Scientific Manuscript database

Our recent study showed that green tea polyphenols (GTP) in conjunction with 1-a-OH¬vit-D3 (vitD3) treatment mitigates lipopolysaccharide (LPS)-induced bone mineral density loss in female rats. This study was undertaken to further explore the mechanism and bone microarchitecture of GTP plus vitD3 in...

Age-dependent increase in oxidative stress in gastrocnemius muscle with unloading

PubMed Central

Siu, Parco M.; Pistilli, Emidio E.; Alway, Stephen E.

2008-01-01

Oxidative stress increases during unloading in muscle from young adult rats. The present study examined the markers of oxidative stress and antioxidant enzyme gene and protein expressions in medial gastrocnemius muscles of aged and young adult (30 and 6 mo of age) Fischer 344 × Brown Norway rats after 14 days of hindlimb suspension. Medial gastrocnemius muscle weight was decreased by ∼30% in young adult and aged rats following suspension. When muscle weight was normalized to animal body weight, it was reduced by 12% and 22% in young adult and aged rats, respectively, after suspension. Comparisons between young adult and aged control animals demonstrated a 25% and 51% decline in muscle mass when expressed as absolute muscle weight and muscle weight normalized to the animal body weight, respectively. H2O2 content was elevated by 43% while Mn superoxide dismutase (MnSOD) protein content was reduced by 28% in suspended muscles compared with control muscles exclusively in the aged animals. Suspended muscles had greater content of malondialdehyde (MDA)/4-hydroxyalkenals (4-HAE) (29% and 58% increase in young adult and aged rats, respectively), nitrotyrosine (76% and 65% increase in young adult and aged rats, respectively), and catalase activity (69% and 43% increase in young adult and aged rats, respectively) relative to control muscles. Changes in oxidative stress markers MDA/4-HAE, H2O2, and MnSOD protein contents in response to hindlimb unloading occurred in an age-dependent manner. These findings are consistent with the hypotheses that oxidative stress has a role in mediating disuse-induced and sarcopenia-associated muscle losses. Our data suggest that aging may predispose skeletal muscle to increased levels of oxidative stress both at rest and during unloading. PMID:18801960

Novel Wnt Regulator NEL-Like Molecule-1 Antagonizes Adipogenesis and Augments Osteogenesis Induced by Bone Morphogenetic Protein 2

PubMed Central

Shen, Jia; James, Aaron W.; Zhang, Xinli; Pang, Shen; Zara, Janette N.; Asatrian, Greg; Chiang, Michael; Lee, Min; Khadarian, Kevork; Nguyen, Alan; Lee, Kevin S.; Siu, Ronald K.; Tetradis, Sotirios; Ting, Kang; Soo, Chia

2017-01-01

The differentiation factor NEL-like molecule-1 (NELL-1) has been reported as osteoinductive in multiple in vivo preclinical models. Bone morphogenetic protein (BMP)-2 is used clinically for skeletal repair, but in vivo administration can induce abnormal, adipose-filled, poor-quality bone. We demonstrate that NELL-1 combined with BMP2 significantly optimizes osteogenesis in a rodent femoral segmental defect model by minimizing the formation of BMP2-induced adipose-filled cystlike bone. In vitro studies using the mouse bone marrow stromal cell line M2-10B4 and human primary bone marrow stromal cells have confirmed that NELL-1 enhances BMP2-induced osteogenesis and inhibits BMP2-induced adipogenesis. Importantly, the ability of NELL-1 to direct BMP2-treated cells toward osteogenesis and away from adipogenesis requires intact canonical Wnt signaling. Overall, these studies establish the feasibility of combining NELL-1 with BMP2 to improve clinical bone regeneration and provide mechanistic insight into canonical Wnt pathway activity during NELL-1 and BMP2 osteogenesis. The novel abilities of NELL-1 to stimulate Wnt signaling and to repress adipogenesis may highlight new treatment approaches for bone loss in osteoporosis. PMID:26772960

Mechanisms of Radiation-Induced Bone Loss and Effects on Prostate Cancer Bone Metastases

DTIC Science & Technology

2013-06-01

and in vivo bone imaging [months 6-10]. b. Determine apoptosis of bone cells (OT, OB & OC) by quantifying TUNEL staining [months 6-10]. Animal...Zoledronic acid will be used as positive control for inhibition of apoptosis and also inhibition of resorption [month 10]. c. Perform in vivo bone imaging ...described and presented in Task 3. Task 5: Image calvarial osteocytes in real-time after single dose exposure of 2 Gy [months 6-12] A single dose of

Serum miRNAs miR-23a, 206, and 499 as Potential Biomarkers for Skeletal Muscle Atrophy

PubMed Central

Wang, Jing; He, Jian; Li, Wenjiong; Li, Jinglong; Chen, Shengju; Zhang, Peng; Liu, Hongju

2017-01-01

Muscle biopsy has long been expected to be replaced by noninvasive biomarkers with diagnostic value and prognostic applications for muscle atrophy. Growing evidence suggests that circulating microRNAs (miRNAs) could act as biomarkers for numerous pathophysiological statuses. In the present study, our results showed that the serum levels of six muscle-specific miRNAs (miR-1/23a/133/206/208b/499) were all elevated in unloading induced mice. The medium levels of these six muscle-specific miRNAs were all elevated in starvation induced atrophic C2C12 myotubes. Moreover, the serum levels of miR-23a/206/499 were induced in participants after 45 days of head-down bed rest (HDBR). The levels of miR-23a/206/499 were positively correlated with the ratio of soleus volume loss in HDBR participants, indicating that they might represent the process of muscle loss. In conclusion, our results demonstrated that circulating miRNAs could serve as useful biochemical and molecular indicators for muscle atrophy diagnosis and disease progression. PMID:29214178

REV-ERBs agonism suppresses osteoclastogenesis and prevents ovariectomy-induced bone loss partially via FABP4 upregulation.

PubMed

Song, Chao; Tan, Peng; Zhang, Zheng; Wu, Wei; Dong, Yonghui; Zhao, Liming; Liu, Huiyong; Guan, Hanfeng; Li, Feng

2018-01-22

REV-ERBs (REV-ERBα and REV-ERBβ) are transcription repressors and circadian regulators. Previous investigations have shown that REV-ERBs repress the expression of target genes, including MMP9 and CX3CR1, in macrophages. Because MMP9 and CX3CR1 reportedly participate in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis, we inferred that REV-ERBs might play a role in osteoclastogenesis. In the present study, we found that the REV-ERBα level decreased significantly during RANKL-induced osteoclast differentiation from primary bone marrow-derived macrophages (BMMs). REV-ERBα knockdown by small interfering RNA in BMMs resulted in the enhanced formation of osteoclasts, whereas REV-ERBβ knockdown showed no effect on osteoclast differentiation. Moreover, the REV-ERB agonist SR9009 inhibited osteoclast differentiation and bone resorption. Intraperitoneal SR9009 administration prevented ovariectomy-induced bone loss; this effect was accompanied by decreased serum RANKL and C-terminal telopeptide of type I collagen levels and increased osteoprotegerin levels. Further investigation revealed that NF-κB and MAPK activation and nuclear factor of activated T cells, cytoplasmic 1, and c-fos expression were suppressed by SR9009. The level of reactive oxygen species was also decreased by SR9009, with NADPH oxidase subunits also being down-regulated. In addition, an expression microarray showed that FABP4, an intracellular lipid-binding protein, was up-regulated by REV-ERB agonism. BMS309403, an inhibitor of FABP4, partially prevented the suppression of osteoclastogenesis by SR9009 through stabilizing phosphorylation of p65. To summarize, our results proved that the REV-ERB agonism inhibited osteoclastogenesis partially via FABP4 up-regulation.-Song, C., Tan, P., Zhang, Z., Wu, W., Dong, Y., Zhao, L., Liu, H., Guan, H., Li, F. REV-ERBs agonism suppresses osteoclastogenesis and prevents ovariectomy-induced bone loss partially via FABP4 upregulation.

Hypercalciuric Bone Disease

NASA Astrophysics Data System (ADS)

Favus, Murray J.

2008-09-01

Hypercalciuria plays an important causal role in many patients with calcium oxalate (CaOx) stones. The source of the hypercalciuria includes increased intestinal Ca absorption and decreased renal tubule Ca reabsorption. In CaOx stone formers with idiopathic hypercalciuria (IH), Ca metabolic balance studies have revealed negative Ca balance and persistent hypercalciuria in the fasting state and during low dietary Ca intake. Bone resorption may also contribute to the high urine Ca excretion and increase the risk of bone loss. Indeed, low bone mass by DEXA scanning has been discovered in many IH patients. Thiazide diuretic agents reduce urine Ca excretion and may increase bone mineral density (BMD), thereby reducing fracture risk. Dietary Ca restriction that has been used unsuccessfully in the treatment of CaOx nephrolithiasis in the past may enhance negative Ca balance and accelerate bone loss. DEXA scans may demonstrate low BMD at the spine, hip, or forearm, with no predictable pattern. The unique pattern of bone histologic changes in IH differs from other causes of low DEXA bone density including postmenopausal osteoporosis, male hypogonadal osteoporosis, and glucocorticoid-induced osteoporosis. Hypercalciuria appears to play an important pathologic role in the development of low bone mass, and therefore correction of urine Ca losses should be a primary target for treatment of the bone disease accompanying IH.

IGF-1 REGULATES VERTEBRAL BONE AGING THROUGH SEX-SPECIFIC AND TIME-DEPENDENT MECHANISMS

PubMed Central

Ashpole, Nicole M; Herron, Jacquelyn C; Mitschelen, Matthew C; Farley, Julie A; Logan, Sreemathi; Yan, Han; Ungvari, Zoltan; Hodges, Erik L.; Csiszar, Anna; Ikeno, Yuji; Humphrey, Mary Beth; Sonntag, William E

2016-01-01

Advanced aging is associated with increased risk of bone fracture, especially within the vertebrae, which exhibit significant reductions in trabecular bone structure. Aging is also associated with a reduction in circulating levels of insulin-like growth factor (IGF-1). Studies have suggested that the reduction in IGF-1 compromises healthspan, while others report that loss of IGF-1 is beneficial as it increases healthspan and lifespan. To date, the effect of decreases in circulating IGF-1 on vertebral bone aging has not been thoroughly investigated. Here, we delineate the consequences of a loss of circulating IGF-1 on vertebral bone aging in male and female Igff/f mice. IGF-1 was reduced at multiple specific time points during the mouse lifespan- early in postnatal development (crossing albumin-Cre mice with Igff/f mice), or early adulthood, and late adulthood using hepatic-specific viral vectors (AAV8-TBG-Cre). Vertebrae bone structure was analyzed at 27 months of age using microCT and quantitative bone histomorphometry. Consistent with previous studies, both male and female mice exhibited age-related reductions in vertebral bone structure. In male mice, reduction of circulating IGF-1 induced at any age did not diminish vertebral bone loss. Interestingly, early-life loss of IGF-1 in females resulted in a 67% increase in vertebral bone volume fraction, as well as increased connectivity density and increased trabecular number. The maintenance of bone structure in the early-life IGF-1-deficient females was associated with increased osteoblast surface and an increased ratio of osteoprotegerin/receptor-activator of NFkB-ligand levels in circulation. Within 3 months of a loss of IGF-1, there was a 2.2 fold increase in insulin receptor expression within the vertebral bones of our female mice, suggesting that local signaling may compensate for the loss of circulating IGF-1. Together, these data suggest the age-related loss of vertebral bone density in females can be reduced by modifying circulating IGF-1 levels early in life. PMID:26260312

Anabolic effects of IGF-1 signaling on the skeleton

PubMed Central

Tahimic, Candice G. T.; Wang, Yongmei; Bikle, Daniel D.

2013-01-01

This review focuses on the anabolic effects of IGF-1 signaling on the skeleton, emphasizing the requirement for IGF-1 signaling in normal bone formation and remodeling. We first discuss the genomic context, splicing variants, and species conservation of the IGF-1 locus. The modulation of IGF-1 action by growth hormone (GH) is then reviewed while also discussing the current model which takes into account the GH-independent actions of IGF-1. Next, the skeletal phenotypes of IGF-1-deficient animals are described in both embryonic and postnatal stages of development, which include severe dwarfism and an undermineralized skeleton. We then highlight two mechanisms by which IGF-1 exerts its anabolic action on the skeleton. Firstly, the role of IGF-1 signaling in the modulation of anabolic effects of parathyroid hormone (PTH) on bone will be discussed, presenting in vitro and in vivo studies that establish this concept and the proposed underlying molecular mechanisms involving Indian hedgehog (Ihh) and the ephrins. Secondly, the crosstalk of IGF-1 signaling with mechanosensing pathways will be discussed, beginning with the observation that animals subjected to skeletal unloading by hindlimb elevation are unable to mitigate cessation of bone growth despite infusion with IGF-1 and the failure of IGF-1 to activate its receptor in bone marrow stromal cell cultures from unloaded bone. Disrupted crosstalk between IGF-1 signaling and the integrin mechanotransduction pathways is discussed as one of the potential mechanisms for this IGF-1 resistance. Next, emerging paradigms on bone-muscle crosstalk are examined, focusing on the potential role of IGF-1 signaling in modulating such interactions. Finally, we present a future outlook on IGF research. PMID:23382729

Effect of whole-body vibration and insulin-like growth factor-I on muscle paralysis-induced bone degeneration after botulinum toxin injection in mice.

PubMed

Niehoff, Anja; Lechner, Philipp; Ratiu, Oana; Reuter, Sven; Hamann, Nina; Brüggemann, Gert-Peter; Schönau, Eckhard; Bloch, Wilhelm; Beccard, Ralf

2014-04-01

Botulinum toxin A (BTX)-induced muscle paralysis results in pronounced bone degradation with substantial bone loss. We hypothesized that whole-body vibration (WBV) and insulin-like growth factor-I (IGF-I) treatment can counteract paralysis-induced bone degradation following BTX injections by activation of the protein kinase B (Akt) signaling pathway. Female C57BL/6 mice (n = 60, 16 weeks) were assigned into six groups (n = 10 each): SHAM, BTX, BTX+WBV, BTX+IGF-I, BTX+WBV+IGF-I, and a baseline group, which was killed at the beginning of the study. Mice received a BTX (1.0 U/0.1 mL) or saline (SHAM) injection in the right hind limb. The BTX+IGF-I and BTX+WBV+IGF-I groups obtained daily subcutaneous injections of human IGF-I (1 μg/day). The BTX+WBV and BTX+WBV+IGF-I groups underwent WBV (25 Hz, 2.1 g, 0.83 mm) for 30 min/day, 5 days/week for 4 weeks. Femora were scanned by pQCT, and mechanical properties were determined. On tibial sections TRAP staining, static histomorphometry, and immunohistochemical staining against Akt, phospho-Akt, IGF-IR (IGF-I receptor), and phospho-IGF-IR were conducted. BTX injection decreased trabecular and cortical bone mineral density. The WBV and WBV+IGF-I groups showed no difference in trabecular bone mineral density compared to the SHAM group. The phospho-IGF-IR and phospho-Akt stainings were not differentially altered in the injected hind limbs between groups. We found that high-frequency, low-magnitude WBV can counteract paralysis-induced bone loss following BTX injections, while we could not detect any effect of treatment with IGF-I.

Measurements of Human Middle- and Inner-Ear Mechanics With Dehiscence of the Superior Semicircular Canal

PubMed Central

Chien, Wade; Ravicz, Michael E.; Rosowski, John J.; Merchant, Saumil N.

2008-01-01

Objectives (1) To develop a cadaveric temporal-bone preparation to study the mechanism of hearing loss resulting from superior semicircular canal dehiscence (SCD) and (2) to assess the potential usefulness of clinical measurements of umbo velocity for the diagnosis of SCD. Background The syndrome of dehiscence of the superior semicircular canal is a clinical condition encompassing a variety of vestibular and auditory symptoms, including an air-bone gap at low frequencies. It has been hypothesized that the dehiscence acts as a “third window” into the inner ear that shunts acoustic energy away from the cochlea at low frequencies, causing hearing loss. Methods Sound-induced stapes, umbo, and round-window velocities were measured in prepared temporal bones (n = 8) using laser-Doppler vibrometry (1) with the superior semicircular canal intact, (2) after creation of a dehiscence in the superior canal, and (3) with the dehiscence patched. Clinical measurements of umbo velocity in live SCD ears (n = 29) were compared with similar data from our cadaveric temporal-bone preparations. Results An SCD caused a significant reduction in sound-induced round-window velocity at low frequencies, small but significant increases in sound-induced stapes and umbo velocities, and a measurable fluid velocity inside the dehiscence. The increase in sound-induced umbo velocity in temporal bones was also found to be similar to that measured in the 29 live ears with SCD. Conclusion Findings from the cadaveric temporal-bone preparation were consistent with the third-window hypothesis. In addition, measurement of umbo velocity in live ears is helpful in distinguishing SCD from other otologic pathologies presenting with an air-bone gap (e.g., otosclerosis). PMID:17255894

Secondary osteoporosis.

PubMed

Gennari, C; Martini, G; Nuti, R

1998-06-01

Generalized osteoporosis currently represents a heterogeneous group of conditions with many different causes and pathogenetic mechanisms, that often are variably associated. The term "secondary" is applied to all patients with osteoporosis in whom the identifiable causal factors are other than menopause and aging. In this heterogeneous group of conditions, produced by many different pathogenetic mechanisms, a negative bone balance may be variably associated with low, normal or increased bone remodeling states. A consistent group of secondary osteoporosis is related to endocrinological or iatrogenic causes. Exogenous hypercortisolism may be considered an important risk factor for secondary osteoporosis in the community, and probably glucocorticoid-induced osteoporosis is the most common type of secondary osteoporosis. Supraphysiological doses of corticosteroids cause two abnormalities in bone metabolism: a relative increase in bone resorption, and a relative reduction in bone formation. Bone loss, mostly of trabecular bone, with its resultant fractures is the most incapacitating consequence of osteoporosis. The estimated incidence of fractures in patients prescribed corticosteroid is 30% to 50%. Osteoporosis is considered one of the potentially serious side effects of heparin therapy. The occurrence of heparin-induced osteoporosis appeared to be strictly related to the length of treatment (over 4-5 months), and the dosage (15,000 U or more daily), but the pathogenesis is poorly understood. It has been suggested that heparin could cause an increase in bone resorption by increasing the number of differentiated osteoclasts, and by enhancing the activity of individual osteoclasts. Hyperthyroidism is frequently associated with loss of trabecular and cortical bone; the enhanced bone turnover that develops in thyrotoxicosis is characterized by an increase in the number of osteoclasts and resorption sites, and an increase in the ratio of resorptive to formative bone surfaces, with the net result of bone loss. Despite these findings, the occurrence of pathological fractures in patients with hyperthyroidism is relatively low, and probably due to the fact that deficiencies in bone mass may be reversed by treatment of the thyroid disease. Most, but not all, studies on insulin-dependent diabetes mellitus (IDDM) report an association with osteopenia. In IDDM, the extent of bone loss is usually slight, which helps explain the discrepancy between the frequency of decreased bone mineral density, and the frequency of osteoporotic fractures in long-standing diabetes. Contradictory results have been obtained in non-insulin-dependent diabetes mellitus (NIDDM) patients. Increased rates of bone loss at the radius and lumbar spine were demonstrated either in patients with two-thirds gastric resection and Billroth II reconstruction, or in those with one-third resection and Billroth I anastomosis, and the metabolic bone disease following gastrectomy may consist also of osteomalacia or mixed pattern of osteoporosis-osteomalacia, with secondary hyperparathyroidism. Miscellaneous causes of secondary osteoporosis are also immobilization, pregnancy and lactation, and alcohol abuse.

Evaluation of potentially significant increase of lead in the blood during long-term bed rest and space flight.

PubMed

Kondrashov, Vladislav; Rothenberg, Stephen J; Chettle, David; Zerwekh, Joseph

2005-02-01

We address a gap in the knowledge of lead turnover under conditions of prolonged bed rest and microgravity by developing a quantitative model of the amount of lead returned to blood circulation from bone. We offer the hypothesis that skeletal unloading, such as typically occurs during extended bed rest or microgravity, will result in bone lead being released to the blood, as has already been demonstrated in the case of calcium. We use initial bone lead concentrations to develop predictive models of blood lead elevation. Our theoretical calculations with typical bone lead loads measured in today's 40-60-year-old generation, suggest that the estimated blood lead concentrations in long duration (e.g., 100 days) space flight could average between 20 and 40 microg dl(-1), a range with well-established toxic effects. For a similar duration of bed rest, estimated blood lead concentration could be as high as 10-20 microg dl(-1), which is a level of concern, particularly if we consider females of childbearing age. The preliminary experimental results were obtained under multi-institutional collaborations, with the main outcome received from an on-going bed rest study, Prevention of Microgravity-Induced Stone Risk by KMgCitrate, conducted at the General Clinical Research Center (GCRC) of the University of Texas Southwestern Medical Center, Dallas. Based on theoretical modeling and some preliminary experimental results, this concept may have important clinical implications by allowing prediction of the magnitude of blood lead elevation, thereby establishing the means to prevent lead toxicity during long duration space flight of astronauts and in conditions of prolonged bed rest such as complicated pregnancy, spinal cord injury induced paralysis and comatose patients.

Bone and glucocorticoids.

PubMed

Briot, Karine

2018-06-01

Corticosteroid-induced osteoporosis is the most common form of secondary osteoporosis and the most frequent cause of osteoporosis in young people. Bone loss and fracture risk increase rapidly after the initiation of corticosteroid therapy and are proportional to dose and treatment duration. The increase in fracture risk is not fully assessed by bone mineral density measurement, as it is also related to impaired bone quality and increased risk of falls. Prevention should be considered in all patients beginning corticosteroid therapy, especially as the underlying inflammation in itself impairs bone quality. Bisphosphonates and teriparatide have shown efficacy in the treatment of corticosteroid-induced osteoporosis. Several national and international guidelines are available to improve management of corticosteroid-induced osteoporosis, which remains inadequate. Duration of anti-osteoporotic treatment should be discussed at the individual level, depending on the subject's characteristics and on the progression of the underlying inflammation. Copyright © 2018. Published by Elsevier Masson SAS.

Euphorbia factor L1 inhibits osteoclastogenesis by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast.

PubMed

Hong, Seong-Eun; Lee, Jiae; Seo, Dong-Hyun; In Lee, Hye; Ri Park, Doo; Lee, Gong-Rak; Jo, You-Jin; Kim, Narae; Kwon, Minjung; Shon, Hansem; Kyoung Seo, Eun; Kim, Han-Sung; Young Lee, Soo; Jeong, Woojin

2017-11-01

Excessive bone resorption caused by increased osteoclast number or activity leads to a variety of bone diseases including osteoporosis, rheumatoid arthritis and periodontitis. Thus, the therapeutic strategy for these diseases has been focused primarily on the inhibition of osteoclast formation and function. This study shows that euphorbia factor L1 (EFL1), a diterpenoid isolated from Euphorbia lathyris, inhibited osteoclastogenesis and induced osteoclast apoptosis. EFL1 suppressed osteoclast formation and bone resorption at both initial and terminal differentiation stages. EFL1 inhibited receptor activator of NF-κB ligand (RANKL)-induced NFATc1 induction with attenuated NF-κB activation and c-Fos expression. EFL1 decreased the level of reactive oxygen species by scavenging them or activating Nrf2, and inhibited PGC-1β that regulates mitochondria biogenesis. In addition, EFL1 induced apoptosis in differentiated osteoclasts by increasing Fas ligand expression followed by caspase activation. Moreover, EFL1 inhibited inflammation-induced bone erosion and ovariectomy-induced bone loss in mice. These findings suggest that EFL1 inhibits osteoclast differentiation by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast, and may provide therapeutic potential for preventing or treating bone-related diseases caused by excessive osteoclast. Copyright © 2017 Elsevier Inc. All rights reserved.

Does bone loss begin after weight loss ends? Results 2 years after weight loss or regain in postmenopausal women.

PubMed

Von Thun, Nancy L; Sukumar, Deeptha; Heymsfield, Steven B; Shapses, Sue A

2014-05-01

Short-term weight loss is accompanied by bone loss in postmenopausal women. The longer-term impact of weight loss on bone in reduced overweight/obese women compared with women who regained their weight was examined in this study using a case-control design. Postmenopausal women (N = 42; mean [SD] body mass index, 28.3 [2.8] kg/m; mean [SD] age, 60.7 [5.5] y) were recruited 2 years after the start of a 6-month weight loss trial; those who maintained their weight (weight loss maintainer [WL-M] group) were matched to a cohort of women who regained their weight (weight loss regainer [WL-R] group). Serum hormones and bone markers were measured in a subset. Bone mineral density (BMD) at the femoral neck, trochanter, spine, radius, and total body, and soft-tissue composition were taken at baseline, 0.5 years, and 2 years. During weight loss, both groups lost 9.3% (3.4%) of body weight, with no significant difference between the groups. After weight loss, weight change was -0.1% (2.7%) and 6.0% (3.3%) in the WL-M (n = 22) and WL-R (n = 20) groups, respectively. After 2 years, both groups lost BMD at the femoral neck and trochanter (P ≤ 0.01), whereas only the WL-M group reduced BMD at the 1/3 radius (P < 0.001). There was greater BMD loss at the trochanter (-6.8% [5.7%]) and 1/3 radius (-4.5% [3.3%]) in the WL-M group compared with the WL-R group after 2 years. Multiple linear regression showed that change in leg fat mass (but not trunk fat) contributed to trochanter BMD loss (P < 0.05). After 2 years, there is no BMD recovery of weight reduction-induced bone loss, irrespective of weight regain. These data suggest that the period after weight loss may be an important point in time to prevent bone loss for those who maintain weight and those who regain weight.

Bone and muscle atrophy with suspension of the rat

NASA Technical Reports Server (NTRS)

Leblanc, A.; Marsh, C.; Evans, H.; Johnson, P.; Schneider, V.; Jhingran, S.

1985-01-01

In order to identify a suitable model for the study of muscle atrophy due to suspension in space, a modified version of the Morey tail suspension model was used to measure the atrophic responses of rat bone and muscle to 14-30 days of unloading of the hindlimbs. The progress of atrophy was measured by increases in methylene diphosphonate (MDP) uptake. It is found that bone uptake of methylene diphosphonate followed a phasic pattern similar to changes in the bone formation rate of immobilized dogs and cats. Increased MDP uptake after a period of 60 days indicated an accelerated bone metabolism. Maximum muscle atrophy in the suspended rats was distinctly different from immobilization atrophy. On the basis of the experimental results, it is concluded that the tail suspension model is an adequate simulation of bone atrophy due to suspension.

Osteoprotective Effect of Alfacalcidol in Female Rats with Systemic Chronic Inflammation

USDA-ARS?s Scientific Manuscript database

Studies have shown that alfacalcidol (a hydroxylated form of vitamin D) mitigates glucocorticoid-induced bone loss. This study was undertaken to explore the mechanism and bone microarchitecture of alfacalcidol in rats with systemic chronic inflammation. Thirty female rats (3-month-old) assigned to ...

Electromagnetically induced transparency with hybrid silicon-plasmonic traveling-wave resonators

NASA Astrophysics Data System (ADS)

Ketzaki, Dimitra A.; Tsilipakos, Odysseas; Yioultsis, Traianos V.; Kriezis, Emmanouil E.

2013-09-01

Spectral filtering and electromagnetically induced transparency (EIT) with hybrid silicon-plasmonic traveling-wave resonators are theoretically investigated. The rigorous three-dimensional vector finite element method simulations are complemented with temporal coupled mode theory. We show that ring and disk resonators with sub-micron radii can efficiently filter the lightwave with minimal insertion loss and high quality factors (Q). It is shown that disk resonators feature reduced radiation losses and are thus advantageous. They exhibit unloaded quality factors as high as 1000 in the telecom spectral range, resulting in all-pass filtering components with sharp resonances. By cascading two slightly detuned resonators and providing an additional route for resonator interaction (i.e., a second bus waveguide), a response reminiscent of EIT is observed. The EIT transmission peak can be shaped by means of resonator detuning and interelement separation. Importantly, the respective Q can become higher than that of the single-resonator structure. Thus, the possibility of exploiting this peak in switching applications relying on the thermo-optic effect is, finally, assessed.

Calcium hydroxide suppresses Porphyromonas endodontalis lipopolysaccharide-induced bone destruction.

PubMed

Guo, J; Yang, D; Okamura, H; Teramachi, J; Ochiai, K; Qiu, L; Haneji, T

2014-05-01

Porphyromonas endodontalis and its main virulence factor, lipopolysaccharide (LPS), are associated with the development of periapical diseases and alveolar bone loss. Calcium hydroxide is commonly used for endodontic therapy. However, the effects of calcium hydroxide on the virulence of P. endodontalis LPS and the mechanism of P. endodontalis LPS-induced bone destruction are not clear. Calcium hydroxide rescued the P. endodontalis LPS-suppressed viability of MC3T3-E1 cells and activity of nuclear factor-κB (NF-κB) in these cells, resulting in the reduced expression of interleukin-6 and tumor necrosis factor-α. In addition, calcium hydroxide inhibited P. endodontalis LPS-induced osteoclastogenesis by decreasing the activities of NF-κB, p38, and ERK1/2 and the expression of nuclear factor of activated T-cell cytoplasmic 1 in RAW264.7 cells. Calcium hydroxide also rescued the P. endodontalis LPS-induced osteoclastogenesis and bone destruction in mouse calvaria. Taken together, our present results indicate that calcium hydroxide suppressed bone destruction by attenuating the virulence of P. endodontalis LPS on bone cells.

Inhibition of bone loss with surface-modulated, drug-loaded nanoparticles in an intraosseous model of prostate cancer.

PubMed

Adjei, Isaac M; Sharma, Blanka; Peetla, Chiranjeevi; Labhasetwar, Vinod

2016-06-28

Advanced-stage prostate cancer usually metastasizes to bone and is untreatable due to poor biodistribution of intravenously administered anticancer drugs to bone. In this study, we modulated the surface charge/composition of biodegradable nanoparticles (NPs) to sustain their blood circulation time and made them small enough to extravasate through the openings of the bone's sinusoidal capillaries and thus localize into marrow. NPs with a neutral surface charge, achieved by modulating the NP surface-associated emulsifier composition, were more effective at localizing to bone marrow than NPs with a cationic or anionic surface charge. These small neutral NPs (~150nm vs. the more usual ~320nm) were also ~7-fold more effective in localizing in bone marrow than large NPs. We hypothesized that NPs that effectively localize to marrow could improve NP-mediated anticancer drug delivery to sites of bone metastasis, thereby inhibiting cancer progression and preventing bone loss. In a PC-3M-luc cell-induced osteolytic intraosseous model of prostate cancer, these small neutral NPs demonstrated greater accumulation in bone within metastatic sites than in normal contralateral bone as well as co-localization with the tumor mass in marrow. Significantly, a single-dose intravenous administration of these small neutral NPs loaded with paclitaxel (PTX-NPs), but not anionic PTX-NPs, slowed the progression of bone metastasis. In addition, neutral PTX-NPs prevented bone loss, whereas animals treated with the rapid-release drug formulation Cremophor EL (PTX-CrEL) or saline (control) showed >50% bone loss. Neutral PTX-NPs did not cause acute toxicity, whereas animals treated with PTX-CrEL experienced weight loss. These results indicate that NPs with appropriate physical and sustained drug-release characteristics could be explored to treat bone metastasis, a significant clinical issue in prostate and other cancers. Copyright © 2016 Elsevier B.V. All rights reserved.

Increased activity of osteocyte autophagy in ovariectomized rats and its correlation with oxidative stress status and bone loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yuehua, E-mail: yuesjtu@126.com; Zheng, Xinfeng, E-mail: zxf272@126.com; Li, Bo, E-mail: libo@126.com

Highlights: • Examine autophagy level in the proximal tibia of ovariectomized rats. • Investigate whether autophagy level is associated with bone loss. • Investigate whether autophagy level is associated with oxidative stress status. - Abstract: Objectives: The objectives of the present study were to investigate ovariectomy on autophagy level in the bone and to examine whether autophagy level is associated with bone loss and oxidative stress status. Methods: 36 female Sprague–Dawley rats were randomly divided into sham-operated (Sham), and ovariectomized (OVX) rats treated either with vehicle or 17-β-estradiol. At the end of the six-week treatment, bone mineral density (BMD) andmore » bone micro-architecture in proximal tibias were assessed by micro-CT. Serum 17β-estradiol (E2) level were measured. Total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity in proximal tibia was also determined. The osteocyte autophagy in proximal tibias was detected respectively by Transmission Electron Microscopy (TEM), immunofluorescent histochemistry (IH), realtime-PCR and Western blot. In addition, the spearman correlation between bone mass, oxidative stress status, serum E2 and autophagy were analyzed. Results: Ovariectomy increased Atg5, LC3, and Beclin1 mRNA and proteins expressions while decreased p62 expression. Ovariectomy also declined the activities of T-AOC, CAT, and SOD. Treatment with E2 prevented the reduction in bone mass as well as restored the autophagy level. Furthermore, LC3-II expression was inversely correlated with T-AOC, CAT, and SOD activities. A significant inverse correlation between LC3-II expression and BV/TV, Tb.N, BMD in proximal tibias was found. Conclusions: Ovariectomy induced oxidative stress, autophagy and bone loss. Autophagy of osteocyte was inversely correlated with oxidative stress status and bone loss.« less

A High-Saturated-Fat, High-Sucrose Diet Aggravates Bone Loss in Ovariectomized Female Rats.

PubMed

Dong, Xiao-Li; Li, Chun-Mei; Cao, Si-Si; Zhou, Li-Ping; Wong, Man-Sau

2016-06-01

Estrogen deficiency in women and high-saturated fat, high-sucrose (HFS) diets have both been recognized as risk factors for metabolic syndrome. Studies on the combined actions of these 2 detrimental factors on the bone in females are limited. We sought to determine the interactive actions of estrogen deficiency and an HFS diet on bone properties and to investigate the underlying mechanisms. Six-month-old Sprague Dawley sham or ovariectomized (OVX) rats were pair fed the same amount of either a low-saturated-fat, low-sucrose (LFS) diet (13% fat calories; 15% sucrose calories) or an HFS diet (42% fat calories; 30% sucrose calories) for 12 wk. Blood, liver, and bone were collected for correspondent parameters measurement. Ovariectomy decreased bone mineral density in the tibia head (TH) by 62% and the femoral end (FE) by 49% (P < 0.0001). The HFS diet aggravated bone loss in OVX rats by an additional 41% in the TH and 37% in the FE (P < 0.05). Bone loss in the HFS-OVX rats was accompanied by increased urinary deoxypyridinoline concentrations by 28% (P < 0.05). The HFS diet induced cathepsin K by 145% but reduced osteoprotegerin mRNA expression at the FE of the HFS-sham rats by 71% (P < 0.05). Ovariectomy significantly increased peroxisome proliferator-activated receptor γ mRNA expression by 136% and 170% at the FE of the LFS- and HFS-OVX rats, respectively (P < 0.05). The HFS diet aggravated ovariectomy-induced lipid deposition and oxidative stress (OS) in rat livers (P < 0.05). Trabecular bone mineral density at the FE was negatively correlated with rat liver malondialdehyde concentrations (R(2) = 0.39; P < 0.01). The detrimental actions of the HFS diet and ovariectomy on bone properties in rats occurred mainly in cancellous bones and were characterized by a high degree of bone resorption and alterations in OS. © 2016 American Society for Nutrition.

Characterization of articular cartilage and subchondral bone changes in the rat anterior cruciate ligament transection and meniscectomized models of osteoarthritis.

PubMed

Hayami, Tadashi; Pickarski, Maureen; Zhuo, Ya; Wesolowski, Gregg A; Rodan, Gideon A; Duong, Le T

2006-02-01

Osteoarthritis (OA) is a chronic joint disease characterized by cartilage destruction, subchondral bone sclerosis, and osteophyte formation. Subchondral bone stiffness has been proposed to initiate and/or contribute to cartilage deterioration in OA. The purpose of this study was to characterize subchondral bone remodeling, cartilage damage, and osteophytosis during the disease progression in two models of surgically induced OA. Rat knee joints were subjected either to anterior cruciate ligament transection (ACLT) alone or in combination with resection of medial menisci (ACLT + MMx). Histopathological changes in the surgical joints were compared with sham at 1, 2, 4, 6, and 10 weeks post-surgery. Using a modified Mankin scoring system, we demonstrate that articular cartilage damage occurs within 2 weeks post-surgery in both surgical models. Detectable cartilage surface damage and proteoglycan loss were observed as early as 1 week post-surgery. These were followed by the increases in vascular invasion into cartilage, in loss of chondrocyte number and in cell clustering. Histomorphometric analysis revealed subchondral bone loss in both models within 2 weeks post-surgery followed by significant increases in subchondral bone volume relative to sham up to 10 weeks post-surgery. Incidence of osteophyte formation was optimally observed in ACLT joints at 10 weeks and in ACLT + MMx joints at 6 weeks post-surgery. In summary, the two surgically induced rat OA models share many characteristics seen in human and other animal models of OA, including progressive articular cartilage degradation, subchondral bone sclerosis, and osteophyte formation. Moreover, increased subchondral bone resorption is associated with early development of cartilage lesions, which precedes significant cartilage thinning and subchondral bone sclerosis. Together, these findings support a role for bone remodeling in OA pathogenesis and suggest that these rat models are suitable for evaluating bone resorption inhibitors as potential disease-modifying pharmaco-therapies.

The Central Nervous System (CNS)-independent Anti-bone-resorptive Activity of Muscle Contraction and the Underlying Molecular and Cellular Signatures*

PubMed Central

Qin, Weiping; Sun, Li; Cao, Jay; Peng, Yuanzhen; Collier, Lauren; Wu, Yong; Creasey, Graham; Li, Jianhua; Qin, Yiwen; Jarvis, Jonathan; Bauman, William A.; Zaidi, Mone; Cardozo, Christopher

2013-01-01

Muscle and bone work as a functional unit. Cellular and molecular mechanisms underlying effects of muscle activity on bone mass are largely unknown. Spinal cord injury (SCI) causes muscle paralysis and extensive sublesional bone loss and disrupts neural connections between the central nervous system (CNS) and bone. Muscle contraction elicited by electrical stimulation (ES) of nerves partially protects against SCI-related bone loss. Thus, application of ES after SCI provides an opportunity to study the effects of muscle activity on bone and roles of the CNS in this interaction, as well as the underlying mechanisms. Using a rat model of SCI, the effects on bone of ES-induced muscle contraction were characterized. The SCI-mediated increase in serum C-terminal telopeptide of type I collagen (CTX) was completely reversed by ES. In ex vivo bone marrow cell cultures, SCI increased the number of osteoclasts and their expression of mRNA for several osteoclast differentiation markers, whereas ES significantly reduced these changes; SCI decreased osteoblast numbers, but increased expression in these cells of receptor activator of NF-κB ligand (RANKL) mRNA, whereas ES increased expression of osteoprotegerin (OPG) and the OPG/RANKL ratio. A microarray analysis revealed that ES partially reversed SCI-induced alterations in expression of genes involved in signaling through Wnt, FSH, parathyroid hormone (PTH), oxytocin, and calcineurin/nuclear factor of activated T-cells (NFAT) pathways. ES mitigated SCI-mediated increases in mRNA levels for the Wnt inhibitors DKK1, sFRP2, and sclerostin in ex vivo cultured osteoblasts. Our results demonstrate an anti-bone-resorptive activity of muscle contraction by ES that develops rapidly and is independent of the CNS. The pathways involved, particularly Wnt signaling, suggest future strategies to minimize bone loss after immobilization. PMID:23530032

The effects of twelve weeks of bed rest on bone histology, biochemical markers of bone turnover, and calcium homeostasis in eleven normal subjects

NASA Technical Reports Server (NTRS)

Zerwekh, J. E.; Ruml, L. A.; Gottschalk, F.; Pak, C. Y.; Blomqvist, C. G. (Principal Investigator)

1998-01-01

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.

Disuse osteopenia induced by botulinum toxin is similar in skeletally mature young and aged female C57BL/6J mice.

PubMed

Vegger, Jens Bay; Brüel, Annemarie; Brent, Mikkel Bo; Thomsen, Jesper Skovhus

2018-03-01

Osteopenia and osteoporosis predominately occur in the fully grown skeleton. However, it is unknown whether disuse osteopenia in skeletally mature, but growing, mice resembles that of fully grown mice. Twenty-four 16-week-old (young) and eighteen 44-week-old (aged) female C57BL/6J mice were investigated. Twelve young and nine aged mice were injected with botulinum toxin in one hind limb; the remaining mice served as controls. The mice were euthanized after 3 weeks of disuse. The femora were scanned by micro-computed tomography (µCT) and bone strength was determined by mechanically testing the femoral mid-diaphysis and neck. At the distal femoral metaphysis, the loss of trabecular bone volume fraction (BV/TV) differed between the young and aged mice. However, at the distal femoral epiphysis, no age-dependent differences were observed. Thinning of the trabeculae was not affected by the age of the mice at either the distal femoral metaphysis or the epiphysis. Furthermore, the aged mice lost more bone strength at the femoral mid-diaphysis, but not at the femoral neck, compared to the young mice. In general, the bone loss induced by botulinum toxin did not differ substantially between young and aged mice. Therefore, the loss of bone in young mice resembles that of aged mice, even though they are not fully grown.

High-fat diet exacerbates pain-like behaviors and periarticular bone loss in mice with CFA-induced knee arthritis.

PubMed

Loredo-Pérez, Aleyda A; Montalvo-Blanco, Carlos E; Hernández-González, Luis I; Anaya-Reyes, Maricruz; Fernández Del Valle-Laisequilla, Cecilia; Reyes-García, Juan G; Acosta-González, Rosa I; Martínez-Martínez, Arisai; Villarreal-Salcido, Jaira C; Vargas-Muñoz, Virginia M; Muñoz-Islas, Enriqueta; Ramírez-Rosas, Martha B; Jiménez-Andrade, Juan M

2016-05-01

Our aim was to quantify nociceptive spontaneous behaviors, knee edema, proinflammatory cytokines, bone density, and microarchitecture in high-fat diet (HFD)-fed mice with unilateral knee arthritis. ICR male mice were fed either standard diet (SD) or HFD starting at 3 weeks old. At 17 weeks, HFD and SD mice received intra-articular injections either with Complete Freund's Adjuvant (CFA) or saline into the right knee joint every 7 days for 4 weeks. Spontaneous pain-like behaviors and knee edema were assessed for 26 days. At day 26 post-first CFA injection, serum levels of IL-1β, IL-6, and RANKL were measured by ELISA, and microcomputed tomography analysis of knee joints was performed. HFD-fed mice injected with CFA showed greater spontaneous pain-like behaviors of the affected extremity as well as a decrease in the weight-bearing index compared to SD-fed mice injected with CFA. Knee edema was not significantly different between diets. HFD significantly exacerbated arthritis-induced bone loss at the distal femoral metaphysis but had no effect on femoral diaphyseal cortical bone. HFD did not modify serum levels of proinflammatory cytokines. HFD exacerbates pain-like behaviors and significantly increases the magnitude of periarticular trabecular bone loss in a murine model of unilateral arthritis. © 2016 The Obesity Society.

Prevention and treatment of bone fragility in cancer patient

PubMed Central

Ottanelli, Silva

2015-01-01

Summary It is well known that fractures increase the risk of morbidity and mortality. The various mechanisms responsible for bone loss in cancer patients may have a different impact depending on the characteristics of the clinical case and correlates with the therapies used, or caused by the therapies used against cancer. Some hormonal treatments cause hypogonadism, event which contributes to the progressive loss of bone mass. This is detectable in patients with breast cancer receiving determines that estrogen-deprivation and in men with prostate cancer with therapies that determine androgen deprivation. Chemotherapy treatments used in cancer patients have reduced bone mass. In addition, low bone mass is detectable in patients with lymphoma treated with corticosteroids or radiation or alkylating agents. In premenopausal patients suffering from breast cancer, treatment with cytotoxic therapy or ablation of ovarian function, can lead to an 8% reduction in bone mineral density at the spine and 4% in the femur. With a chemotherapy regimen in CMF, the reduction of BMD is 6.5%; this bone loss is not recovered after discontinuation of therapy. Tamoxifen given for five years reduces bone remodeling and cause a 32% increase in the risk of osteoporotic fractures when used in premenopausal. After menopause, tamoxifen has a protective effect on bone mass, with a reduced risk of new fractures. Aromatase inhibitors in post-menopausal women, depending on the formulation can cause different effects on the reduction of BMD and fracture risk. We have in fact steroids, exemestane and nonsteroidal, letrozole and anastrozole. Patients at increased risk of fragility fractures should undergo preventive therapies as soon as possible after tests performed for the study of bone health. They can be used DEXA and the FRAX algorithm, which can define a secondary osteoporosis. Prevention and treatment of the increased risk of osteoporotic fracture is to maintain adequate levels of calcium and vitamin D. Bisphosphonates and denosumab are used for the management of bone remodeling and bone loss induced by cancer treatments. Bisphosphonates also have anti-tumor effects per se, which are expressed in potentially prevent the development of bone metastases. In men with metastatic prostate cancer and which is induced androgen deprivation, it is usefully used denosumab 120 mg monthly or zoledronic acid 4 mg monthly. PMID:26604936

Altered ovarian function affects skeletal homeostasis independent of the action of follicle-stimulating hormone.

PubMed

Gao, Jianjun; Tiwari-Pandey, Rashmi; Samadfam, Rana; Yang, Yinzhi; Miao, Dengshun; Karaplis, Andrew C; Sairam, M Ram; Goltzman, David

2007-06-01

Osteoporosis is a leading public health problem. Although a major cause in women is thought to be a decline in estrogen, it has recently been proposed that FSH or follitropin is required for osteoporotic bone loss. We examined the FSH receptor null mouse (FORKO mouse) to determine whether altered ovarian function could induce bone loss independent of FSH action. By 3 months of age, FORKO mice developed age-dependent declines in bone mineral density and trabecular bone volume of the lumbar spine and femur, which could be partly reversed by ovarian transplantation. Bilateral ovariectomy reduced elevated circulating testosterone levels in FORKO mice and decreased bone mass to levels indistinguishable from those in ovariectomized wild-type controls. Androgen receptor blockade and especially aromatase inhibition each produced bone volume reductions in the FORKO mouse. The results indicate that ovarian secretory products, notably estrogen, and peripheral conversion of ovarian androgen to estrogen can alter bone homeostasis independent of any bone resorptive action of FSH.

Is increased joint loading detrimental to obese patients with knee osteoarthritis? A secondary data analysis from a randomized trial.

PubMed

Henriksen, M; Hunter, D J; Dam, E B; Messier, S P; Andriacchi, T P; Lohmander, L S; Aaboe, J; Boesen, M; Gudbergsen, H; Bliddal, H; Christensen, R

2013-12-01

To investigate whether increased knee joint loading due to improved ambulatory function and walking speed following weight loss achieved over 16 weeks accelerates symptomatic and structural disease progression over a subsequent 1 year weight maintenance period in an obese population with knee osteoarthritis (OA). Data from a prospective study of weight loss in obese patients with knee OA (the CARtilage in obese knee OsteoarThritis (CAROT) study) were used to determine changes in knee joint compressive loadings (model estimated) during walking after a successful 16 week weight loss intervention. The participants were divided into 'Unloaders' (participants that reduced joint loads) and 'Loaders' (participants that increased joint loads). The primary symptomatic outcome was changes in knee symptoms, measured with the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire, during a subsequent 52 weeks weight maintenance period. The primary structural outcome was changes in tibiofemoral cartilage loss assessed semi-quantitatively (Boston Leeds Knee Osteoarthritis Score (BLOKS) from MRI after the 52 weight maintenance period. 157 participants (82% of the CAROT cohort) with medial and/or lateral knee OA were classified as Unloaders (n = 100) or Loaders (n = 57). The groups showed similar significant changes in symptoms (group difference: -2.4 KOOS points [95% CI -6.8:1.9]) and cartilage loss (group difference: -0.06 BLOKS points [95% CI -0.22:0.11) after 1 year, with no statistically significant differences between Loaders and Unloaders. For obese patients undergoing a significant weight loss, increased knee joint loading for 1 year was not associated with accelerated symptomatic and structural disease progression compared to a similar weight loss group that had reduced ambulatory compressive knee joint loads. NCT00655941. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Formononetin prevents ovariectomy-induced bone loss in rats.

PubMed

Ha, Hyekyung; Lee, Ho Young; Lee, Je-Hyun; Jung, Dayoung; Choi, Jiyoon; Song, Kye-Yong; Jung, Hee Jin; Choi, Jae Sue; Chang, Soo-Ik; Kim, Chungsook

2010-04-01

The major risk factor of postmenopausal osteoporosis is estrogen deficiency. Hormone replacement therapy is efficacious against osteoporosis, but it induces several significant adverse effects. In this study, therefore, we compared therapeutic potencies of three phytoestrogens: genistein, daidzein, and formononetin. Our result showed that in Saos-2 cells, formononetin and genistein (5 x 10(-7) M) treatment increased alkaline phosphatase activity by 33.0 +/- 5.8% and 21.1 +/- 4.0%. Genistein inhibited osteoclast formation in a dose-dependent manner. In OVX rats, formononetin-treated groups given 1 and 10 mg/kg/day displayed increased trabecular bone areas (TBAs) within the tibia. Genistein- and daidzein-treated groups also displayed increased tibial TBAs. TBAs of the lumbar vertebrae were higher in all treated groups than in the control group. In conclusion, formononetin as well as other isoflavones, such as daidzein and genistein, inhibited bone loss caused by estrogen-deficiency.

Induced Pluripotent Stem Cell Derived Mesenchymal Stem Cells for Attenuating Age-Related Bone Loss

DTIC Science & Technology

2013-09-01

formation, are associated with gastrointestinal problems when taken orally and may cause osteonecrosis in cancer patients and bone pain in other...expression of osteoblastic phenotypic markers on iPS derived MSC cultured on nanotopographic biofilms . While we have not yet examined the effect

Effects of β-Glucans Ingestion on Alveolar Bone Loss, Intestinal Morphology, Systemic Inflammatory Profile, and Pancreatic β-Cell Function in Rats with Periodontitis and Diabetes

PubMed Central

Silva, Viviam de O.; Lobato, Raquel V.; Orlando, Débora R.; Borges, Bruno D.B.; de Sousa, Raimundo V.

2017-01-01

This study aimed to evaluate the effects of β-glucan ingestion (Saccharomyces cerevisiae) on the plasmatic levels of tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10), alveolar bone loss, and pancreatic β-cell function (HOMA-BF) in diabetic rats with periodontal disease (PD). Besides, intestinal morphology was determined by the villus/crypt ratio. A total of 48 Wistar rats weighing 203 ± 18 g were used. Diabetes was induced by the intraperitoneal injection of streptozotocin (80 mg/kg) and periodontal inflammation, by ligature. The design was completely randomized in a factorial scheme 2 × 2 × 2 (diabetic or not, with or without periodontitis, and ingesting β-glucan or not). The animals received β-glucan by gavage for 28 days. Alveolar bone loss was determined by scanning electron microscopy (distance between the cementoenamel junction and alveolar bone crest) and histometric analysis (bone area between tooth roots). β-glucan reduced plasmatic levels of TNF-α in diabetic animals with PD and of IL-10 in animals with PD (p < 0.05). β-glucan reduced bone loss in animals with PD (p < 0.05). In diabetic animals, β-glucan improved β-cell function (p < 0.05). Diabetic animals had a higher villus/crypt ratio (p < 0.05). In conclusion, β-glucan ingestion reduced the systemic inflammatory profile, prevented alveolar bone loss, and improved β-cell function in diabetic animals with PD. PMID:28906456