bluuebunny/crossref_metadata_2025_split huggingface dataset:
Force attenuation properties of various trochanteric padding materials under typical falling conditions of the elderly
Authors: Parkkari Jari , Kannus Pekka , Poutala Jarmo , Vuori Ilkka 
Published: February 2010

Abstract
The purpose of this study was to determine and compare the force attenuation properties of various external trochanteric padding materials under in vitro conditions simulating characteristic falling of the elderly. The selected materials had to be practically suitable for external hip padding so that the main criteria for the materials were good energy absorbing capacity, good durability, low weight, good recovery after compression, easy availability, and reasonable price. Eight materials met these requirements. The first six were flexible cross-linked polyethylene foams with densities from 30 to 200 kg/m3. The seventh material was Plastazote polyethylene foam, and the eighth foam was made of ethylene-vinyl acetate (EVA) copolymer. With a pendulum effective mass of 39 kg, impact velocity of 3.0 m/s, and impact force of 8.2 kN, the force attenuation provided by the 20 mm thick hip-padding materials was quite small, ranging from 22 to 38%. With all these materials the peak femoral force remained above 5 kN, more than two times above the femoral fracture threshold (2 kN). In the second set of experiments, the impact force was gradually reduced until the tested materials lowered the impact force below the fracture threshold. With the most efficient material this critical falling velocity was found to be 1.6 m/s. To go below the fracture threshold with the realistic impact velocity of 3.0 m/s, the padding materials had to be 100-140 mm thick. In conclusion, our test results strongly suggest that using reasonable thicknesses of the currently available hip padding materials, the impact forces clearly remain above the fracture threshold, and therefore, prevention of hip fractures by external protectors should be based on other ideas (increase in the impact surface and/or shunting of impact energy away from the greater trochanter) than hip padding alone.
Displacement and translocation of osteoblast-like cells by osteoclasts
Authors: Ferrier Jack , Xia Shen-Ling , Lagan Eva , Aubin Jane E. , Heersche Johan N. M. 
Published: February 2010

Abstract
Rabbit osteoclasts and rabbit osteoblast-like stroma cells (OB cells) were plated onto plastic surfaces and the migration patterns of individual osteoclasts and osteoclast-OB interactions were analyzed with time-lapse recording. To induce directed migration, the cultures were exposed to an electrical field of 0.01 or 0.1 V/mm. At 0.1 V/mm, osteoclasts moved directly toward the anode in some cases, clearing OB cells from their path of migration. In other cases, osteoclasts migrated toward the anode for part of the time but then changed direction and moved toward groups of OB cells. Observations were made on osteoclasts interacting with single OB cells or small colonies and on osteoclasts interacting with OB monolayers, at both field strengths; the results were independent of field strength. There were several characteristic behaviors. With single OB cells and small OB colonies, retraction of OB cells upon contact with the osteoclast was the predominant mechanism whereby these cells begin to move out of the path of the osteoclast. A pronounced ruffling or blebbing of the OB cell membrane often followed retraction. When osteoclasts displaced OB cells that were part of a monolayer, extension of an osteoclast lamellipodium underneath the edge of the OB cell layer generally preceded partial retraction of the OB cells involved. It sometimes appeared as if the detached or partially detached OB cells were “pushed” by the osteoclast, which in some cases resulted in OB cells being moved hundreds of μm in a period of a few hours, at rates comparable to the normal speed for osteoclast migration (⋍100 μm/h), much faster than the normal speed for OB cells (⋍10 μm/h). These results imply that osteoclasts have mechanisms to move OB cells out of their path of migration. Further, when these cells were plated onto devitalized bone slices, resorbing osteoclasts apparently were able to clear a path through the OB cells. Laser scanning fluorescent measurements showed that there was no general intracellular [Ca2+] increase in OB cells following contact with osteoclasts, suggesting that an intracellular [Ca2+] signaling cascade does not play a role in the OB displacement. These data support the hypothesis that osteoclasts obtain access to the bone surface by actively displacing osteoblasts or lining cells at sites earmarked for resorption.
Dual X-ray absorptiometry forearm software: Accuracy and intermachine relationship
Authors: Hagiwara Satoshi , Engelke Klaus , Yang Seoung-Oh , Dhillon Manjit S. , Guglielmi Giuseppe , Nelson David L. , Genant Harry K. 
Published: February 2010

Abstract
An ash study was performed to analyze the accuracy of forearm measurements at the one-third site of three dual x-ray absorptiometry (DXA) systems using 20 cadavers. A Hologic QDR-2000, a Hologic QDR-1000/W, and a Lunar DPX-L system were used. The correlations between ash weight and DXA BMC were excellent for the three instruments (r &gt; 0.97, p &lt; 0.001), with accuracy errors &lt; 5.2%. To perform a forearm cross-calibration of bone mineral content (BMC) and density (BMD) between the scanners, 10 healthy volunteers were additionally scanned at the distal one-third radius. The correlations among the DXA machines were excellent (r &gt; 0.95); the absolute BMC and BMD values were significantly different between the two Hologics and the Lunar machine. The slope and intercept of both the BMC and BMD between the two Hologic systems were close to unity. In conclusion, the DXA forearm software packages provide accurate methods for assessing bone mineral content and density. The conversion of data among different manufacturers should be performed by careful cross-calibration measurements.
Calcitonin inhibits testosterone and luteinizing hormone secretion through a mechanism involving an increase in camp production in rats
Authors: Dr. Wang Paulus S. , Tsai Shiow-Chwen , Hwang Guey-Shyang , Wang Shyi-Wu , Lu Chien-Chen , Chen Jiann-Jong , Liu Shy-Rong , Lee Kun-Yih , Chien Eileen Jea , Chien Chau-Heng , Lee Hsien-Yang , Lau Chin-Pang , Tsai Ching-Lin 
Published: February 2010

Abstract
Effects of calcitonin peptides, including human calcitonin (hCT), salmon calcitonin (sCT), and calcitonin gene-related peptide (CGRP), on the secretion of testosterone and luteinizing hormone (LH) in male rats were studied. Male rats were injected intravenously with human chorionic gonadotropin (hCG), calcitonin peptides, or hCG plus calcitonin peptides. Blood samples were collected at several intervals following hormone challenge. In an in vitro experiment, testis blocks were incubated with hCG (0, 0.05, 0.5, or 5 IU/ml) or hCG (0.5 IU/ml) plus calcitonin peptides (0–10−9 or 10−6 M) at 34°C for 30 minutes. Both medium and plasma samples were extracted by ether and analyzed for testosterone by radioimmunoassay (RIA). The concentration of calcium in each plasma sample was measured by an automatic calcium analyzer. The anterior pituitary gland (AP) was incubated with or without calcitonin peptides (0–10 nM) at 37°C for 30 minutes. They were then incubated with gonadotropin releasing hormone (GnRH, 10 nM) for a further 30 minutes. The concentration of LH in AP medium was measured by RIA. The accumulation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in both testicular tissues and APs were measured by RIA. A single intravenous injection of calcitonin peptides decreased the basal and hCG-stimulated levels of plasma testosterone gradually from 60 to 180 or 360 minutes after challenge. The plasma calcium was not altered by the injection of calcitonin peptides and/or hCG. Administration of calcitonin peptides in vitro resulted in a dose-dependent inhibition of both basal and hCG-stimulated release of testosterone. Meanwhile, calcitonin peptides caused a dose-dependent inhibition of the basal release of LH in vitro from rat APs. The content of cAMP in both testes and APs was increased by all calcitonin peptides. Neither hCT nor sCT altered the content of cGMP in testes and APs. These results suggest that calcitonin peptides, including hCT, sCT, and CGRP, inhibit the spontaneous and gonadotropin-stimulated secretion of testosterone by acting directly at testes and reducing the release of pituitary LH through a mechanism involving an increase in cAMP production.
Serum undercarboxylated osteocalcin correlates with hip bone mineral density in elderly women
Authors: Szulc Pawel , Arlot Monique , Chapuy Marie-Claire , Duboeuf Francois , Meunier Pierre J. , Dr. Delmas Pierre D. 
Published: February 2010

Abstract
We previously showed that circulating undercarboxylated osteocalcin (ucOC) is elevated in elderly women and is a powerful marker of the subsequent risk of hip fracture in elderly institutionalized women (J Clin Invest 1993; 91:1769). To investigate the relationship between bone mass and ucOC, we measured bone mineral density (BMD) of the hip with dual-energy x-ray absorptiometry in 98 elderly institutionalized women, 81.4 + 6.0 years old. ucOC was negatively correlated with BMD at all sites (r = –0.26 to –0.38, p &lt; 0.001 to p &lt; 0.0001), even after exclusion of the effect of age by partial correlation (for the femoral neck, r = –0.26, p &lt; 0.01) and after controlling for serum parathyroid hormone. BMD was significantly lower at all sites of measurement in women with elevated ucOC (&gt; 1.65 ng/ml, upper limit of the normal range in young women) than in those with normal ucOC (for the neck, 0.58 + 0.13 versus 0.43 + 0.13 g/cm2, p &lt; 0.001). Similar results were obtained for ucOC expressed as the fraction of total OC (ucOC %). Multiple regression showed that ucOC has the highest predictive value for BMD when including age and body weight in the equation. In summary, our data indicate that serum ucOC is an independent determinant of BMD of the hip in elderly women. The mechanism by which serum ucOC is related to bone mass is unclear and should be addressed in further studies. However, our data suggest that ucOC level may be an interesting marker in the investigation of bone status in the elderly.
Bone mass improves in alcoholics after 2 years of abstinence
Authors: Peris Pilar , Parés Albert , Guan̄abens Núria , Del Río Luis , Pons Francesca , De Osaba Maria Jesús Martínez , Monegal Ana , Caballería Joan , Rodés Joan , Muñoz-Gómez José 
Published: February 2010

Abstract
To evaluate the effect of abstinence on bone mass and bone mineral metabolism in chronic alcoholics, a 2 year longitudinal follow-up study was carried out in a group of 30 chronic alcoholic males who started a rehabilitation program. Lumbar and femoral bone mineral density (BMD) and serum levels of osteocalcin and 25-hydroxyvitamin D were measured at entry and after 1 and 2 years in all patients. Circulating cortisol and parathyroid hormone were measured in 14 and 6 patients, respectively, at entry and every year. Testosterone was measured in 18 patients at entry and after 1 year. At entry, lumbar BMD was significantly lower in alcoholics (1.06 + 0.03 g/cm2) than in age-matched healthy men (1.22 + 0.03 g/cm2; p &lt; 0.001). Circulating osteocalcin and vitamin D levels were also significantly lower in alcoholics than in controls. Lumbar and femoral neck BMD increased in alcoholics after 2 years of abstinence (lumbar BMD, mean + SEM, 1.06 + 0.03 to 1.10 + 0.04 g/cm2, p &lt; 0.05; femoral BMD, 0.82 + 0.02 to 0.84 + 0.02 g/cm2; p &lt; 0.02). Moreover, lumbar BMD increased in alcoholics (2.9 + 1.4%) and decreased in controls (–1.1 + 0.2%; p &lt; 0.02). Femoral BMD also increased in alcoholics (2.8 + 1.0%) but the expected mean decrease of –0.92% was found in healthy age-matched males. Baseline low osteocalcin levels (5.1 + 0.6 ng/ml) increased after 1 year (8.6 + 0.5 ng/ml, p &lt; 0.001) and 2 years of abstinence (9.5 + 0.7 ng/ml, p &lt; 0.001). No significant changes in 25-hydroxyvitamin D, parathyroid hormone, testosterone, or cortisol levels were observed throughout the study. Presence and severity of liver disease did not correlate with bone mass changes. We conclude that in chronic alcoholics lumbar and femoral neck bone mass improves after abstinence. The increase in circulating osteocalcin without associated changes in other circulating hormones further supports the hypothesis that alcohol has deleterious effects on bone formation.
Direct, enzyme-linked immunoassay for urinary deoxypyridinoline as a specific marker for measuring bone resorption
Authors: Dr. Robins Simon P. , Woitge Henning , Hesley Robert , Ju Julia , Seyedin Saeid , Seibel Markus J. 
Published: February 2010

Abstract
Several studies in recent years have shown that the pyridinium crosslinks of collagen provide good urinary markers of collagen degradation, primarily reflecting bone resorption. Most studies, however, were based on time-consuming HPLC assays of the crosslinks. We now describe the development of an immunoassay (ELISA) based on a monoclonal antibody for free deoxypyridinoline (Dpd) and its use in healthy individuals and patients with bone-related disorders to measure the urinary excretion of Dpd as an improved assessment of bone resorption rate. The Dpd antibody exhibited less than 1% cross-reaction with free pyridinoline and was shown to react only with free Dpd in urine, having no significant interaction with peptide forms of the crosslinks. The intra- and interassay variations were less than 10 and 15%, respectively. A total of 402 urine samples from patients and healthy volunteers were analyzed by both the immunoassay and HPLC. The ELISA results were highly correlated with those for total Dpd measured by HPLC over the full range of sample groups (r = 0.95). In normal adults, the excretion of Dpd (mean + SD) was 4.7 + 1.6 nmol/mmol creatinine, with about fivefold higher excretion rates in children. For 31 osteoporotic patients, the ELISA Dpd values (median 6.7; range 3.0–13.5 nmol/mmol Cr) were significantly higher (p &lt; 0.0001) than the corresponding values for age- and sex-matched controls (median 4.0; range 1.8–7.4). The difference between the groups was similar for total Dpd by HPLC (osteoporotic: mean 12.8, range 4.8–30.7; controls: 6.6, range 3.0–18.1; p &lt; 0.0001). For other patient groups, comparisons of the Dpd excretion with healthy controls revealed similar differences for both the immunoassay and total Dpd analyses in primary HPT (n = 23: p &lt; 0.0001), Paget's disease (n = 28, p &lt; 0.0001), renal dysfunction (n = 26, no significant difference), and breast cancer (n = 17, p &lt; 0.0001). We conclude that the immunoassay constitutes a simpler, more direct way of assessing bone resorption rates that provides similar information to the more cumbersome HPLC methods.
Brittle bones in spontaneously diabetic female rats cannot be predicted by bone mineral measurements: Studies in diabetic and ovariectomized rats
Authors: Verhaeghe J. , Suiker A.M.H. , Einhorn T.A. , Geusens P. , Visser W.J. , van Herck E. , van Bree R. , Magitsky S. , Bouillon R. 
Published: February 2010

Abstract
Spontaneously diabetic BB rats were sham operated (SO) or ovariectomized (OVX) within days after onset and studied after 4, 8, and 12 weeks. Analyses included histomorphometry of proximal tibial metaphyses, biochemical analyses of humeri, DXA analyses, and biomechanical testing of femora. In SO diabetic rats, no osteoblasts, osteoid tissue, or osteoclasts were present on the trabecular bone surface, but trabecular bone volume (TBV) remained normal compared with control BB rats. The concentration of IGF-I per dry weight of humerus was decreased after 12 weeks of diabetes, whereas the concentrations of calcium and osteocalcin did not change. DXA analysis showed normal bone mineral density (BMD) at both diaphyseal and metaphyseal femoral areas. On biomechanical testing, angular deformation, energy absorption, and torsional strength of the femora were decreased after 8–12 weeks of diabetes, but stiffness was normal. Ovariectomy in diabetic rats caused a decrease in femoral BMD especially at the metaphysis, and there was a trend toward decreased TBV in the tibial metaphysis; TBV loss was less marked than in control OVX rats, however. The increase in BMD at the femoral diaphysis, measured after 12 weeks of OVX in control rats, was absent in diabetic rats. Multiple-regression analysis indicated that the presence of diabetes but not ovariectomy, weight, and mineral content correlated with decreased energy absorption, angular deformation, and strength of the femora. The data infer that the (near) absence of unmineralized bone matrix in severely diabetic rats alters bone microarchitecture and ultimately results in brittle bones, which is not predicted by BMC or BMD measurements.
Fluctuation of mineral apposition rate at individual bone-remodeling sites in human iliac cancellous bone: Independent correlations with osteoid width and osteoblastic alkaline phosphatase activity
Authors: Bradbeer Jeremy N. , Lindsay Peter C. , Reeve Jonathan 
Published: February 2010

Abstract
We investigated the determinants of bone formation at individual remodeling sites (BMUs) in cancellous bone from 8 osteologically normal, sex hormone-replete women with endometriosis. All were tetracycline double- labeled (2, 12, 2, and 4 day regime) before iliac bone biopsy. At each BMU the mineral apposition rate (MAR) was determined conventionally from the distance between label midpoints (MAR 1) and also from the distance between the mineralization front and the trailing edge of the second label (MAR 2). MAR 1 and 2 were compared with within-BMU measurements of osteoid width (O.Wi) and the activities of osteoblastic alkaline phosphatase (AP) and succinic dehydrogenase (SDH, an enzyme in the Krebs cycle), both quantitated by microdensitometry. A total of 143 BMUs were evaluated, of which 88 were satisfactory for all measurements and 132 were satisfactory for all but SDH. There was a weak correlation (r = 0.34) between MAR 1 and 2 at individual sites, with a mean difference of 0.49 μm/day (mean MAR 0.82 μm/day). The mean MAR of individual subjects tended to be either increasing or decreasing (F = 16.1, p &lt; 0.01). In linear regressions, MAR 2 was statistically dependent on O.Wi, AP, and SDH (73% of the variance accounted for). In contrast, MAR 1 was weakly correlated with O.Wi and only 30% of its variance was accounted for by AP, SDH, and O.Wi. The variance in the MAR 2 data was inversely increased (p &lt; 0.01) compared with MAR 1 as the number of days of bone formation represented. The data are best explained by large within-BMU variations in MAR over periods of up to a few days and longer term trends affecting all BMUs. Correlations between fluctuation in MAR and osteoblastic AP and SDH activity suggest that bone formation depends partly on AP activity and osteoblast energy balance. Random obliquity of sectioning has considerable theoretical effects on some correlations (e.g., between O.Wi and MAR), but further investigation emphasized the likely biologic importance of the correlations involving enzyme activities.
Characteristics and properties of osteocytes in culture
Authors: van der Plas A. , Aarden E.M. , Feijen J.H.M. , de Boer A.H. , Wiltink A. , Alblas M.J. , de Leij L. , Nijweide P.J. 
Published: February 2010

Abstract
Although the osteocyte is the most abundant among the highly differentiated cells of mature bone (osteocytes, lining cells, osteoblasts, and osteoclasts), its properties and functions are the least known and understood. Here we isolated osteocytes from mixed populations of bone cells liberated from fetal chick calvariae by alternate treatments with collagenase and EDTA. The osteocytes were removed from the bone cell populations by binding them via an osteocyte-specific antibody (MAb OB 7.3) to magnetic beads and removing the beads together with the coupled osteocytes from the population using a magnet. Isolated osteocytes were found to be highly differentiated, postmitotic cells that required their typical stellate morphology in culture. Osteocyte populations had alkaline phosphatase (ALP) activity somewhat lower than that of the osteoblast-like cell populations from which they were separated by the immunodissection procedure. On the single-cell level, the ALP activity was highly variable. Parathyroid hormone (PTH) receptors were found to be present on osteocytes as well as on osteoblast-like cells, but not on fibroblast-like cells of the outer periosteum. In response to PTH, osteocytes increased their intracellular levels of cAMP, as did the osteoblast-like cells. Osteocytes appeared to be somewhat more sensitive to PTH than osteoblasts. When seeded onto dentin slices, osteocytes did not corrode the dentin surface to any appraisable degree. We therefore found no evidence to support the notion that osteocytes play a role in the calcium homeostasis through osteocytic osteolysis. Whether osteocytes play an important role in perceiving and transducing hormonal and/or mechanical stimuli remains open for future research.
Comparison of radiographic absorptiometry with dual-energy X-ray absorptiometry and quantitative computed tomography in normal older white and black women
Authors: Kleerekoper Michael , Nelson Dorothy A. , Flynn Michael J. , Pawluszka Annie S. , Jacobsen Gordon , Peterson Edward L. 
Published: February 2010

Abstract
Bone mineral density (BMD) of the phalanges of the hand was measured by the technique of radiographic absorptiometry (RA) in 199 older postmenopausal women previously determined to have normal BMD by dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). The average age of the women was 66.8 ± 4.9 years, and they were 19.9 ± 6.7 years postmenopause. In the 54 black women, phalangeal BMD was 11.7% greater than in the 145 white women, a difference comparable to that found using DXA at the radial midshaft, the lumbar spine, and femoral neck. A correlation matrix comparing BMD measured by RA to BMD measured by DXA and QCT indicates that, in general, RA was related to the various DXA and QCT measurement sites as well as these sites were related to each other. When results for RA, DXA, and QCT obtained in our cohort of older women were compared to available reference data for peak adult bone mass, the average difference (SD units) from peak value was greatest for RA (-1.77 radius, −1.24 spine, −2.13 femoral neck, −2.34 QCT spine, and −2.71 phalanges). We conclude that RA is an acceptable measure of phalangeal BMD and that the data in our cohort can serve as reference data for older white and black women aged 55–75 years. Once the ability of RA to predict future fracture occurrence has been demonstrated, it could be rapidly deployed as a low-cost, widely available bone mass measurement technique.