bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exercise effects on bone mass in postmenopausal women are site-specific and load-dependent
Authors: Kerr Deborah , Morton Alan , Dick Ian , Prince Richard 
Published: February 2010

Abstract
It is considered that skeletal mass in humans may respond to loading or the number of loading cycles. The aim of this study was to examine the effect of a 1 year progressive resistance training program on the bone mass of 56 postmenopausal women. Assignment was by block randomization to one of two resistance training groups: a strength trained group (3 × 8 repetition maximum) or an endurance group (3 × 20 repetition maximum). The resistance exercises were selected to stress the ipsilateral forearm and hip region. The exercising side was randomly assigned with one side exercised while the alternate side acted as the nonexercise control. Bone mineral density (BMD) was measured every 3 months at the radial forearm and four hip sites using the Hologic QDR 2000 bone densitometer. A linear regression function was fitted for each individual's bone density results, and the slope was compared for the exercise and control side using paired t-tests. The bone mass increase with the strength regimen was significantly greater at the trochanteric hip site (control -0.6 + 2.2%, exercise 1.7 + 4.1%,p &lt; 0.01), at the intertrochanteric hip site (control -0.1 + 2.1%, exercise 1.5 + 3.0%,p &lt; 0.05), Ward's triangle (control 0.8 + 5.2%, exercise 23 + 4.0%,p &lt; 0.05), and at the ultradistal radial site (control -1.4 + 2.3%, exercise 2.4 + 4.3%. p &lt; 0.01). There was no significant increase in BMD with the endurance regimen except at the radius midsite (control -1.0 + 23%, exercise 0.1 + 1.4%, p &lt; 0.01). In both the endurance and the strength group, muscle strength, tested by a one-repetition maximum (IRM) test, increased significantly for all 10 exercises (p &lt; 0.01) and to a similar degree in the two groups. In the strength group but not the endurance group there were significant correlations between the slope of the change in BMD and the percentage increase in strength as follows: trochanter with leg press; intertrochanter with leg press (p &lt; 0.05); and Ward's triangle with hip extension and hip adduction (p &lt; 0.05). Thus these results support the notion of a site-specific response of bone to maximal loading from resistance exercise in that although the trochanter and intertrochanteric bone density was elevated by the resistance exercises undertaken, there was no effect on the femoral neck value. Postmenopausal bone mass can be significantly increased by a strength regimen that uses high-load low repetitions but not by an endurance regimen that uses low-load high repetitions. We conclude that the peak load is more important than the number of loading cycles in increasing bone mass in early postmenopausal women.
Bone mineral mass consolidation in young British adults
Authors: Parsons Tessa J. , Prentice Ann , Smith Elisabeth A. , Cole Tim J. , Compston Juliet E. 
Published: February 2010

Abstract
Forty males and 40 females, ages 18–21 years, were recruited into a prospective study to investigate the consolidation of bone mineral after cessation of linear growth and the influences of calcium intake, lifestyle factors, physical activity, and body composition on bone. Three sets of bone measurements were made annually at the spine, hip, and whole body (dual-energy X-ray absorptiometry) and at the wrist and midshaft radius (single photon absorptiometry). At baseline, the bone mineral content (BMC) was significantly greater in males than females at all sites (p &lt; 0.004). After adjustment for scan area (BA), height, weight, and age, male BMC was significantly greater than female BMC at the midshaft radius (+7.4%; p &lt; 0.01) but lower at the spine (-10.9%; p &lt; 0.001) with no difference at the wrist, hip, or whole body. Positive effects of leanness on bone were observed in females but not in males. Dietary calcium, nutrient intakes, and physical activity levels were not size-independent determinants of BMC at any site. Significant increases in whole-body BMC were observed within individuals over the study period of 670 (SD 51) days, +13% in males and +2.1% in females (p &lt; 0.01), mirrored by increases in BMC and BA at most skeletal sites. After allowing for changes in BA, significant increases (p &lt; 0.01) were observed in adjusted BMC for the whole body (males, +1.1%; females, +0.6%), lumbar spine (males, +1.5%; females, +1.1%), and midshaft radius (males, +1.9%; females, +2.0%). No lifestyle or anthropometric factors were identified that influenced these longitudinal increases in bone mineral.
Trabecular bone morphology from micro-magnetic resonance imaging
Authors: Hipp John A. , Jansujwicz Alan , Simmons Craig A. , Snyder Brian D. 
Published: February 2010

Abstract
Micro-magnetic resonance imaging (micro-MRI) is potentially a widely available tool to image and quantify the three-dimensional structure of trabecular bone. However, it has not been demonstrated that the same quantitative measurements can be obtained using micro-MRI as would be obtained from conventional light microscope images. Bovine trabecular bone from several anatomic sites was imaged with both optical and micro-MRI methods. The six faces of approximately cubic trabecular bone specimens were examined with the light microscope, and the volume of bone internal to these faces was then imaged using an 8.6 T 25 mm bore magnet. Three-dimensional measures of bone morphology were calculated from both the optical and micro-MR images using the method of directed secants. Quantitative measures from the two imaging methods were compared by paired f-tests. Volume fractions (BV/TV) measured by micro-MRI were linearly related to (r2 = 0.81) and did not differ statistically from (p = 0.96) similar measurements from optical images. The trabecular plate number (Tb.N) measured by micro-MRI also was linearly related to (r2 = 0.53) and did not differ statistically from (p = 0.17) similar measurements from optical images. The orientation of trabeculae predicted from micro-MRI was within 6° of that calculated from optical images in 10 out of 16 specimens. The micro-MRI morphology measurements are relatively easy to perform, and since several hundred small-bore high-field strength MRI systems are available, this technique could be used widely to quantify the morphology of trabecular bone.
Constitutive in vivo mRNA expression by osteocytes of β-actin, osteocalcin, connexin-43, IGF-I, c-fos and c-jun, but not TNF-α nor tartrate-resistant acid phosphatase
Authors: Mason Deborah J. , Hillam Richard A. , Dr. Skerry Timothy M. 
Published: February 2010

Abstract
Osteocytes have been proposed to be the cells primarily responsible for sensing the effects of mechanical loading in bone. Osteocytes respond to loading in vivo, and have been shown to express osteotropic agents and their receptors, and cell/matrix adhesion molecules in vitro, but the functional significance of such findings is not clear. One obstacle to increased understanding of the role of osteocytes in the regulation of bone mass is that the cells are not easily accessible for study. In situ studies are difficult, and although it is possible to extract and culture osteocytes from neonatal bones, the responses of such cells might be very different from those in older bones in situ. We have developed a technique to investigate osteocyte gene expression in vivo, using the reverse transcriptase linked polymerase chain reaction (PCR), and have shown that they express mRNA for β-actin (β-ACT), osteocalcin (OC), connexin-43 (Cx43), insulin-like growth factor I (IGF-I), c-fos, and c-jun, but not tumor necrosis factor alpha (TNF-α) or tartrate-resistant acid phosphatase (TRAP). The principle behind the method is that after removal of the periosteum, tangential cryostat sections of a tubular bone contain RNA only from osteocytes and a very small number of endothelial cells as long as the marrow cavity is not broached. Using this method, we have investigated gene expression in cells from rat ulnar cortical bone under forming and resorbing bone surfaces. In addition, we have investigated the effect on gene expression of mechanical loading which, if repeated daily, initiates new bone formation on quiescent or resorbing surfaces. Although the expression of the genes we have studied in osteocytes is different from those expressed by the periosteal surfaces overlying the cortex, we have not detected loading-related changes in osteocyte gene expression in any cortical bones. This may be because of the extreme sensitivity of the PCR technique which can only resolve large differences in expression. The use of quantitative methods in the future may allow demonstration of regulated gene expression in osteocytes.
Interleukin-4 inhibits prostaglandin G/H synthase-2 and cytosolic phospholipase A2 induction in neonatal mouse parietal bone cultures
Authors: Kawaguchi Hiroshi , Nemoto Ken , Raisz Lawrence G. , Harrison John R. , Voznesensky Olga S. , Alander Cynthia B. , Pilbeam Carol C. 
Published: February 2010

Abstract
We have shown previously that prostaglandin (PG) production in 7-day-old neonatal mouse calvarial cultures is regulated largely by changes in prostaglandin G/H synthase-2 (PGHS-2) expression and to a lesser extent by changes in arachidonic acid (AA) release. In this study, we examined the effects of interleukin-4 (IL-4), and its interactions with other cytokines and with parathyroid hormone (PTH), on mRNA levels of PGHS-2, PGHS-1, and cytosolic phospholipase A2 (cPLA2) and on medium protaglandin E2 (PGE2) levels in calvarial cultures. IL-1 and tumor necrosis factor-α (TNF-α), both at 1–100 ng/ml, and PTH at 0.1-10 nM increased PGHS-2 and cPLA2 mRNA and medium PGE2 levels dose-dependently after 4 h of treatment. IL-6 and IL-11 at 1–100 ng/ml did not affect mRNA or PGE2 levels. IL-4 at 1–100 ng/ml decreased PGHS-2 and cPLA2 mRNA and PGE2 levels in control as well as IL-1, TNF-α, and PTH-stimulated cultures. The inhibition of PGHS-2 and cPLA2 mRNA expression by IL-4 (10 ng/ml) was present at 1 h, reached a maximum at 4 h, and persisted for 24 h. The effects were maintained in the presence of cycloheximide. IL-4 also decreased PGHS-2 protein levels in control and IL-1-stimulated cultures. PGHS-1 mRNA levels were not stimulated by any of the factors studied nor inhibited by IL-4. IL-4 partially inhibited control and PTH-stimulated 45Ca release from prelabeled mouse calvariae at 4 days. However, neither the inhibition of resorption by IL-4 nor the stimulation by IL-1 and PTH were altered by indomethacin (1 μM). We conclude that (1) IL-1, TNF-α, and PTH, but not IL-6 nor IL-11, can increase the expression of PGHS-2, cPLA2, and PGE2 production in cultured mouse calvariae; (2) IL-4 inhibits PGE2 production in both control and stimulated calvarial cultures by inhibiting PGHS-2 and cPLA2; and (3) IL-4 has an inhibitory effect on bone resorption which is independent of PG production.
1,25-Dihydroxyvitamin D3—mediated transforming growth factor-β release is impaired in cultured osteoblasts from patients with multiple pituitary hormone deficiencies
Authors: Sterck Jozien G. H. , Klein-Nulend Jenneke , Burger Elisabeth H. , Lips Paul 
Published: February 2010

Abstract
To evaluate the osteoblastic function in patients with multiple pituitary hormone deficiencies (M-PHD) and with isolated growth hormone deficiency (I-GHD), bone cells were cultured and the effects of 10−8 M 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) on parameters of cell proliferation, osteoblastic differentiation, and local paracrine regulation were measured. Three days of 1,25(OH)2D3 treatment increased alkaline phosphatase activity and osteocalcin release but inhibited [3H]thymidine incorporation in all cell cultures from patients as well as from controls. In addition, 1,25(OH)2D3 increased the release of both total and active transforming growth factor-β (TGF-β) in bone cells from controls by, respectively, 4.9- and 3.2-fold and in bone cells from I-GHD by 5.1- and 1.5-fold, respectively. However, in bone cells from M-PHD, the stimulation of total TGF-β release was significantly lower (1.3-fold) than in control and I-GHD cells, and active TGF-β release was not stimulated at all. One year of supplementation with human growth hormone did not improve this deficient TGF-β release in bone cells from M-PHD. We conclude that cultured bone cells from I-GHD and M-PHD show a normal response to 1,25(OH)2D3 regarding cell proliferation and osteoblastic differentiation, which implicates a normal l,25(OH)2D3-receptor function. In cells from controls and I-GHD, 1,25(OH)2D3 enhanced both total and active TGF-β release. However, bone cells from M-PHD showed a deficient TGF-β response to 1,25(OH)2D3. These results suggest that the regulation of TGF-β production is a major paracrine factor involved in hypopituitarism.
The effect of impact direction on the structural capacity of the proximal femur during falls
Authors: Ford Catherine M. , Keaveny Tony M. , Hayes Wilson C. 
Published: February 2010

Abstract
As with any structure, the structural capacity of the proximal femur depends on the applied loads and these can vary as a function of impact direction during a fall. However, despite its potential importance in hip fracture risk assessment, the relative importance of impact direction is unknown. To investigate the role of impact direction in hip fracture, we developed a detailed finite element model of the proximal femur. We analyzed four loading configurations that represent a range of possible falls on the greater trochanter. Our results indicate that a change in the angle between the line of action of the applied force and the axis of the femoral neck from 0° (representing a direct lateral impact) to 45° (representing a posterolateral impact) reduced structural capacity by 26%. This weakening of the femur with changes in impact direction is comparable to the weakening associated with 2–3 decades of age-related bone loss. Our result elucidates the independent contribution of fall mechanics to hip fracture risk by identifying an aspect of the fall (the direction of impact) that is an important determinant of fall severity. The results can also be incorporated into a refined clinical method for assessment of hip fracture risk that accounts for the complex interactions between fall severity and bone fragility.
Contributions of vertebral fractures to stature loss among elderly Japanese-American women in Hawaii
Authors: Dr. Huang Chun , Ross Philip D. , Lydick Eva , Davis James W. , Wasnich Richard D. 
Published: February 2010

Abstract
Loss of stature is a typical feature of osteoporosis and associated vertebral fractures. However, there have been few prospective population-based studies to estimate the magnitude of this association. Further, the separate contributions of different types of vertebral fractures to stature loss have not been evaluated using prospective data. In this study we investigated the extent to which stature loss could be explained by the number of different types of vertebral fractures (wedge, endplate, and crush fractures) after adjusting for other covariates. Longitudinal data on stature loss and vertebral fractures were collected among 504 postmenopausal Japanese-American women living in Hawaii with mean age 73.4 (SD 4.9) years. During an average of 7.7 years of follow-up, women with at least one incident vertebral fracture had an average of 2.1 cm of stature loss while the average stature loss among those without incident fractures was only 0.4 cm. The mean rate of stature loss was very slight (&lt; 1 mm/year) for those without incident vertebral fractures even after age 80. Our analyses suggest that both the number of wedge and the number of crush fractures are strong predictors of stature loss. After adjusting for age and total height loss in the anterior dimension over T3-L5, the estimated stature loss resulting from each wedge and crush fracture was 0.86 and 1.08 cm, respectively. Endplate fractures did not show significant contributions to stature loss.
Effects of continuous calcitonin treatment on osteoclast-like cell development and calcitonin receptor expression in mouse bone marrow cultures
Authors: Ikegame Mika , Rakopoulos Maryann , Martin T. John , Moseley Jane M. , Dr. Findlay David M. 
Published: February 2010

AbstractContinuous treatment with calcitonin (CT) to inhibit osteoclastic bone resorption results in acquired resistance. The mechanisms of this “escape” phenomenon are not yet established. The aim of this study was to examine the effects of continuous treatment with CT on the generation of osteoclasts and calcitonin receptor (CTR) expression in mouse bone marrow cultures. This was done by daily CT treatment of mouse bone marrow cultures from day 0, when only undifferentiated mononuclear precursors of osteoclast-like cells were present, or commencing from day 6, when differentiated osteoclast-like cells were abundant. The response to CT treatment was determined by quantitation of cells positive for tartrate-resistant acid phosphatase (TRAP) and binding of 125I-salmon CT. Calcitonin receptor and TRAP mRNA levels were determined using semi-quantitative reverse transcription/polymerase chain reaction. When cultures were treated with CT from day 0, TRAP-positive multinucleated cells appeared. These cells expressed only very low levels of CTR or CTR mRNA and were morphologically indistinguishable from osteoclast-like cells formed in control cultures. They also displayed the ability to resorb bone. Continuous CT treatment of cultures from day 6 rapidly reduced the CTR mRNA levels, with a t1/2 of 6 to 12 h, and these levels remained low thereafter. 125I-salmon CT binding capacity, as determined by autoradiography, was lost in parallel. These effects were specific for the CTR since there was no consistent effect on TRAP mRNA levels. Based on these data, we suggest that the “escape” phenomenon may result from a prolonged CT-induced loss of CT responsiveness due, at least in part, both to reduced synthesis of CTR, and to the appearance in bone of CTR-deficient osteoclasts.
Ectopic secretion of osteocalcin, the major non-collagenous bone protein, by the myeloma cell line NCI-H929
Authors: Barille Sophie , Pellat-Deceunynck Catherine , Bataille Regis , Amiot Martine 
Published: February 2010

Abstract
In this study we provide the first evidence that human non-osteoblastic cells secrete the bone-specific protein osteocalcin. We show that the myeloma cell line NCI-H929 constitutively produces low amounts of osteocalcin. Furthermore, we demonstrate that this production is strongly enhanced after 1,25(OH)2D3 stimulation. An amplification or a deregulation of the osteocalcin gene could be responsible for the observed phenomenon because NCI-H929 has the unusual characteristic of having at least three chromosomes 1, where the osteocalcin gene was mapped (1q25-q31). It is of interest to note that the patient in whom the NCI-H929 cell line originated never developed osteolytic lesions despite extensive disease apparent at autopsy. Although lytic bone lesions with low osteocalcin serum levels are a common feature of multiple myeloma (MM), a small subset of patients does not develop lytic bone lesions or even demonstrate osteosclerotic MM. This occurrence is associated with high osteocalcin serum levels of unknown origin. In this context, osteocalcin production by immortalized tumor lacking any osteolytic potential could be relevant to the pathophysiology of this particular type of MM.
A digital model of trabecular bone
Authors: Engelke K. , Song S.M. , Glüer C.C. , Genant H.K. 
Published: February 2010

Abstract
A 3D μCT dataset of bovine bone was used to create a digital 3D model simulating trabecular bone. The model serves a dual purpose: It allows for standard quantitative histomorphometric analysis and it approximates the reality e.g. of high resolution CT in vivo datasets of trabecular bone. Thus the model can potentially be used as a reference to develop 2D and 3D structural analysis algorithms applicable in vivo while it simultaneously allows verification of the results of these algorithms by standard histomorphometry. The model can be used as a standard to evaluate the impact of image processing techniques and of restrictions of imaging systems on the quantitative analysis of structural parameters describing a trabecular network. The model can be used for a comparison of 2D and 3D structural analysis methods and for an analysis of decreasing spatial resolution. The effects of segmentation and filtration can be studied separately and grayscale analysis is possible. As examples standard 2D histomorphometry and the analysis of topological parameters like node number and trabecular network length were applied to the model. The influence of spatial resolution was investigated by decreasing the spatial resolution of the digital model. The bone surface area determined by 3D surface triangulation was only 4% smaller than the surface area determined from the traditional 2D bone histomorphometric parameter bone surface/tissue volume (BS/TV) when 2D results were averaged over all slices of the 3D volume. However, BS/TV showed large (10%) variations among slices within the volume. Both histomorphometric and topological parameters were heavily influenced by spatial resolution and image segmentation. Our initial experience with the digital model indicates a need to investigate bone microstructure based on volume data or to average the 2D results of many slices.
Effects of unilateral strength training and detraining on bone mineral mass and estimated mechanical characteristics of the upper limb bones in young women
Authors: Heinonen Ari , Sievänen Harri , Kannus Pekka , Oja Pekka , Vuori Ilkka 
Published: February 2010

Abstract
The aims of this study were to examine the effects of 12 months unilateral high-resistance strength training and 8-month detraining on bone mineral content (BMC), density (BMD) and estimated mechanical characteristics of upper limb bones, and also to estimate consequent loading induced strains on forearm bone shafts. Thirteen female physiotherapy students (mean 23.8 ± 5.0 yrs, 166 ± 7 cm, 64.4 ± 13.3 kg) trained their left upper limbs with dumbbells on average 2.8 times per week for 12 months, followed by eight months detraining. Nineteen students served as controls (mean 25.7 ± 5.2 yrs, 16.5 ± 4 cm, 62.1 ± 7.0 kg). BMC, BMD, and bone width and estimated cortical wall thickness (CWT) were measured at five different sites in both upper extremities (proximal humerus, humeral shaft, radial shaft, ulnar shaft, and distal forearm) using dual energy x-ray absorptiometry (DXA) scanner. In addition, cross-sectional moment of inertia (CSMI) was estimated from DXA data. The maximal isometric strength of the upper extremities was measured with an arm flexion-extension dynamometer. The training increased significantly the flexion strength by 14% (p = 0.001). During the detraining period, all measured strength values in the training group decreased in both limbs with respect to values after training. Despite the clear effect on muscular strength, no significant intergroup differences were observed in BMC, BMD, bone width, CWT, or CSMI values at any measured site after the training or detraining period. The estimated loading-induced strains remained within customary loading, and the change in strain level was only 15%. In conclusion, this study indicated that using high-resistance strength training may not provide an effective osteogenic stimulus for bone formation and geometric changes in upper limb bones of young, healthy, adult women. The interaction of bones and muscles may play an important and relatively unrecognized role in the development of bone strength, suggesting that the entire biomechanical environment should be carefully considered when evaluating the osteogenic efficiency of physical loading.