bluuebunny/crossref_metadata_2025 huggingface dataset:
Low bioavailable testosterone levels predict future height loss in postmenopausal women
Authors: Jassal Simerjot K. , Barrett-Connor Elizabeth , Edelstein Sharon L.
Published: February 2010

The objective of this study was to examine the relation of endogenous sex hormones to subsequent height loss in postmenopausal women, in whom height loss is usually a surrogate for osteoporotic vertebral fractures. This was a prospective, community-based study. The site chosen was Rancho Bernardo, an upper middle class community in Southern California. A total of 170 postmenopausal women participated, aged 55–80 years. None of them were taking exogenous estrogen between 1972 and 1974. Plasma was obtained for sex hormone and sex hormone-binding globulin (SHBG) assays. Estradiol/SHBG and testosterone/SHBG ratios were used to estimate biologically available hormone levels; bioavailable (non-SHBG-bound) testosterone was measured directly in 60 women. Height loss was based on height measurements taken 16 years apart. Height loss was strongly correlated with age (p = 0.001). These women lost an average 0.22 cm/year in height. Neither estrone nor estradiol levels were significantly and independently related to height loss. Both estimated bioavailable testosterone (testosterone/SHBG ratio) and measured bioavailable testosterone levels predicted future height loss (p = 0.02 and 0.08, respectively) independent of age, obesity, cigarette smoking, alcohol intake, and use of thiazides and estrogen. We conclude that bioavailable testosterone is an independent predictor of height loss in elderly postmenopausal women. The reduced height loss is compatible with a direct effect of testosterone on bone mineral density or bone remodeling.
Prevention of hypercalciuria and stone-forming propensity during prolonged bedrest by alendronate
Authors: Ruml Lisa A. , Dubois Susan K. , Roberts Marsha L. , Pak Charles Y.C.
Published: February 2010

The bone loss and hypercalciuria induced by immobilization or the decreased gravitational forces of space are well described. Using a model of bedrest immobilization, the ability of a potent aminobisphosphonate, alendronate, to avert hypercalciuria and stone-forming propensity was tested. Sixteen male subjects participated in a randomized, placebo-controlled trial in which they received either 20 mg of alendronate or placebo 2 weeks prior to and during 3 weeks of strict bedrest. Parameters of bone and calcium metabolism and urinary crystallization of stone-forming salts were measured before and at the end of bedrest. In the placebo group, bedrest increased urinary calcium (209 ± 47 to 267 ± 60 mg/day, p < 0.01) and the saturation of calcium phosphate. Before bedrest, the alendronate group had a significantly lower serum calcium (8.8 ± 0.4 vs. 9.6 ± 0.5 mg/dl, p ≥ 0.01) and higher serum PTH (62.4 ± 33.1 vs. 23.1 ± 7.5 pg/ml, p > 0.01) compared with the placebo group. Moreover, the alendronate group had a lower urinary calcium (75 ± 41 mg/day) and saturation of calcium oxalate and calcium phosphate. These effects of alendronate were sustained during bedrest. Following bedrest in the alendronate group, urinary calcium rose to 121 ± 50 mg/day, a value less than that in the placebo group before or during bedrest. Similarly, urinary saturation of calcium oxalate and calcium phosphate rose with bedrest in the alendronate-treated patients but remained lower than values obtained in placebo-treated patients before or during bedrest. Alendronate inhibits bone mineral loss and averts the hypercalciuria and increased propensity for the crystallization of stone-forming calcium salts which occurs during 3 weeks of strict bedrest.
Influence of spontaneous calcium intake and physical exercise on the vertebral and femoral bone mineral density of children and adolescents
Authors: Ruiz J.C. , Mandel C. , Dr. Garabedian M.
Published: February 2010

Peak bone mass is determined mainly by genetic-ethnic factors, but environmental factors such as calcium intake and physical activity during childhood and adolescence could play a role. We have measured the bone mineral density (BMD) of 151 healthy children and adolescents, ages 7–153 years. Density was measured by dual X-ray absorptiometry (DXA) at two sites (lumbar verterbrae L1–L4 and the upper femur), and the data were analyzed in terms of the height, weight, sexual maturation, spontaneous calcium intake, and physical activity. Of the children, 57–71% had calcium intakes below 1000 mg/day. BMD increased with pubertal maturation from 0.68 ± 0.08 to 0.92 ± 0.09 g/cm2 (vertebral bone density, VBD) and from 0.87 ± 0.10 to 1.03 ± 0.09 g/cm2 (femoral bone density, FBD) between Tanner stage 1 and 5. Multiple regression analysis showed that body weight and Tanner stage were main determinants of bone density when expressed as g/cm2. The weekly duration of sports activity also influenced both the vertebral (p < 0.001) and femoral (p = 0.01) sites, especially in girls and during puberty. Dietary calcium appeared to be another independent determinant of BMD, especially before puberty, at the vertebral (p = 0.02) site. Most important, dietary calcium was found to be the main determinant of vertebral mineral density, when expressed as z score, in both sexes. Moreover, 93% of the 28 children with low vertebral z score values (below –1) and 84% of the 31 children with low femoral z score values (below –1) had dietary calcium intakes below 1000 mg/day.
Inhibitors of ER Ca2+-ATPase activity deplete the ATP- and thrombin-sensitive Ca2+ pool in UMR 106–01 osteosarcoma cells
Authors: Meszaros Gary J. , Dr. Karin Norman J.
Published: February 2010

While calcium release from intracellular stores is a signaling mechanism used universally by cells responding to hormones and growth factors, the compartmentalization and regulated release of calcium is cell type-specific. We employed thapsigargin and 2,5,-di-(tert-butyl)-1,4-benzohydroquinone (tBuHQ), two inhibitors of endoplasmic reticulum (ER) Ca2+-ATPase activity which block the transport of Ca2+ into intracellular stores, to characterize free Ca2+ compartmentalization in UMR 106–01 osteoblastic osteosarcoma cells. Each drug elicited transient increases in cytosolic free Ca2+ ([Ca2+]i), followed by a stable plateau phase which was elevated above the control [Ca2+]i. The release of Ca2+ from intracellular stores was coupled to an increased plasma membrane Ca2+ permeability which was not due to L-type Ca2+ channels. Thapsigargin and tBuHQ emptied the intracellular calcium pool which was released in response to either ATP or thrombin, identifying it as the inositol 1,4,5-trisphosphate-sensitive calcium store. The results of sequential and simultaneous additions of thapsigargin and tBuHQ indicate that both drugs depleted the same Ca2+ store and inhibited the same Ca2+-ATPase activity.
Peak bone mass in young women
Authors: Teegarden Dorothy , Proulx William R. , Martin Berdine R. , Zhao Jian , Mccabe George P. , Lyle Roseann M. , Peacock Munro , Slemenda Charles , Johnston Conrad C. , Weaver Connie M.
Published: February 2010

Increasing peak bone mineral density (BMD) or content (BMC) in young women may help to reduce the incidence of osteoporosis. Identifying the age when peak bone content or density is attained is essential to develop strategies aimed at optimizing peak BMD and BMC. Total body bone mineral density (TBBMD) and content (TBBMC) were measured by a dual X-ray absorptiometer in healthy females (n = 247, aged 11–32 years). TBBMD and TBBMC were modeled separately as a nonlinear function of age. By age 22.1 ± 2.5 years, 99% of peak BMD is attained, and by age 26.2 ± 3.7 years, 99% of peak BMC is attained. Nonlinear relationships between weight and TBBMD or TBBMC were also modeled. In this model, the influence of several parameters, including age, weight, and height, on BMC and BMD were simultaneously assessed. A model with age and weight described the best fit for TBBMD, whereas age, weight, and height described the best fit for total body TBBMC.
Thapsigargin stimulates intracellular calcium mobilization and inhibits parathyroid hormone release
Authors: Dr. Shoback Dolores , Chen Tsui-Hua , Pratt Stacy , Lattyak Bruce
Published: February 2010

Ca2+ and other divalent cations like Sr2+, Ba2+, and Mg2+ stimulate rapid and sustained increases in intracellular Ca2+ ([Ca2+]i) and 1,4,5-inositol trisphosphate (1,4,5-InsP3) presumably by interacting with recently identified parathyroid cell membrane Ca2+ receptors. We used thapsigargin (THAPS), an inhibitor of the microsomal Ca2+-ATPase, to deplete InsP3-sensitive intracellular Ca2+ stores to determine whether sustained increases in [Ca2+]i due to divalent cations require intact cytosolic Ca2+ pools. In Fura 2-loaded parathyroid cells, THAPS produced a gradual increase in [Ca2+]i which reached a steady-state level by 2–3 minutes. The effect of THAPS (3 × 10−6 M) was substantial with [Ca2+]i, rising from 281 ± 27 nM at 0.5 mM Ca2+ to a peak value of 684 ± 30 nM (p < 0.0001). The addition of Sr2+ to cells at 0.5 mM extracellular Ca2+ induced an immediate 2-to 3-fold increase in [Ca2+]i which stabilized at a [Ca2+]i above baseline for ≥10 minutes. THAPS (3 × 10−6 M) pretreatment for ≥5 minutes blocked this sustained-phase increment in [Ca2+]i due to Sr2+. In the absence of extracellular Ca2+, there was a slight but nonsignificant effect of THAPS on [Ca2+]i. Incubation of cells with THAPS did not change the levels of 3H-inositol phosphates (InsP3, InsP2, and InsP1) or alter Sr2+-induced accumulation of InsP3, InsP2, and InsP1. THAPS substantially reduced parathyroid hormone secretion at 1.0 mM Ca2+ by 20 ± 16, 57 ± 8, 75 ± 10, and 83 ± 9% at 10−7, 3 × 10−7, 10−6, and 3 × 10−6 M THAPS, respectively. We conclude that depletion of intracellular Ca2+ stores by THAPS stimulates Ca2+ mobilization, presumably from extracellular sources, and that this agent and divalent cations such as Sr2+ activate the same pathway for sustained Ca2+ mobilization. The inhibition of secretion by THAPS supports the idea that increases in [Ca2+]i play a suppressive role in the control of hormone release in the parathyroid.
Generation and characterization of a human osteosarcoma cell line stably transfected with the human estrogen receptor gene
Authors: Huo Bin , Dossing Debra A. , Dimuzio Michael T.
Published: February 2010

Although 17β-estradiol (E2) replacement therapy has been shown to be effective in treating postmenopausal osteoporosis, the underlying mechanism remains unclear. The presence of low levels of functional endogenous estrogen receptor (ER) in some osteoblastic cells has been demonstrated, and the suggestion that the abundance of ER may be rate-limiting in the action of E2 on these cells has been made. To study the mechanism of ER in regard to E2-mediated effects, we stably transfected a human osteosarcoma cell line, SaOS-2, with an expression vector, pMV-7-ER, containing the human ER gene. We characterized six of the stably transfected clones. One of the stable clones, SaOS-2-ER, expressed extra copies of ER genes integrated into the genome as detected by Southern blot analysis, showed a significantly increased level of ER mRNA by RT-PCR, and contained an increased level of ER cytosolic protein as detected by an ER-specific EIA. The overexpressed ER was functional and sensitive to E2 in a dose-dependent fashion after transient transfection with a vector containing an estrogen response element (ERE) linked to a chloramphenicol acetyltransferase (CAT) reporter gene. Scatchard analysis revealed a single high-affinity binding site with a Kd similar to values obtained for the ER in MCF-7 breast cancer cells. These SaOS-2-ER cells had altered osteoblast phenotypic features including growth inhibition, decreased basal alkaline phosphatase activity, and decreased IL-6 expression and secretion. In response to E2, a greater than 2-fold increase in TGF-β1 mRNA was quantitatively measured in these ER-overexpressing osteoblasts. These cells may provide a sensitive and unique model for understanding the mechanism of E2 and ER in overall bone metabolism.
Physical exercise during remobilization restores a normal bone trabecular network after tail suspension-induced osteopenia in young rats
Authors: Dr. Bourrin Sandrine , Palle Sabine , Genty Christian , Alexandre Christian
Published: February 2010

To determine how bone recovers from immobilization-induced bone loss and to specify whether its recovering capacity is improved by physical exercise, 5-week-old male Wistar rats (287.07 g ± 10.65 SD) were tail suspended for 14 days, then returned to either normal weight-bearing (R) or controlled physical exercise for 28 days (R + E). Bone mineral density (BMD) was measured in three parts of the femur. Using histomorphometric analysis, bone mass and architecture were estimated in the primary (1°sp) and secondary spongiosa (2°sp) of the proximal tibial metaphysis. Bone cellular parameters were measured in the 2°sp of the tibia. Tail suspension induced a significant decrease in BMD, 2°sp bone mass, mineral apposition rate, and bone formation rate and marked alterations of the trabecular network. In R rats, BMD was still significantly decreased, except in the distal part of the femur. Long-bone lengthening was significantly altered. The 2°sp bone mass returned to the age-matched control values; however, the trabeculae were still significantly thinner and bone resorption was significantly higher. R + E rats had a normal long bone lengthening and a significant increase in 2°sp bone mass and trabecular thickness when compared with R rats. Bone resorption was significantly depressed, and osteoid surfaces and thickness were significantly increased. Thus, although bone mass returns to normal values in the R group, trabecular alterations persist. Physical exercise during recovery helps restore a normal trabecular network, and the depressed bone resorption associated with an increased bone formation leads to an increased bone volume.
The skeletal effects of spaceflight in growing rats: Tissue-specific alterations in mrna levels for TGF-β
Authors: Dr. Westerlind Kim C. , Turner Russell T.
Published: February 2010

Dynamic weight bearing is important for normal growth and maintenance of the skeleton in humans and laboratory animals. Transforming growth factor-beta (TGF-β) has been implicated as having autocrine and paracrine actions in bone. The purpose of this study was to examine mRNA levels of TGF-β in skeletal tissues of growing male rats following skeletal unweighting during an 11-day spaceflight. Animals were sacrificed 5–8 h after the skeleton was reloaded. Spaceflight resulted in decreases in cortical bone area and periosteal bone formation, but no change in medullary area and endocortical bone formation. In addition, spaceflight had no effect on longitudinal bone growth. TGF-β was reduced relative to the ground controls in the hindlimb periosteum, but was not significantly altered in the growth zone of the tibial metaphysis. Similarly, mRNA levels for type I collagen were reduced in the periosteum, but not in the metaphysis of flight animals. The results suggest a potential role of TGF-β as an intermediate in the signal transduction pathway for mechanical loading. Further, they indicate skeletal tissue compartment-dependent changes in mRNA levels for TGF-β following weightlessness.
Comparison of methods for defining prevalent vertebral deformities: The study of osteoporotic fractures
Authors: Black Dennis M. , Palermo Lisa , Nevitt Michael C. , Genant Harry K. , Epstein Robert , Valentin Ria San , Cummings Steven R.
Published: February 2010

Women with vertebral deformities caused by osteoporosis have more back pain and disability and are at higher risk for subsequent vertebral deformities than women without deformities. Despite the importance of vertebral deformities, there has been a great deal of controversy about how to identify or define them. In order to compare methods for defining vertebral deformities, we studied spinal radiographs from women in the Study of Osteoporotic Fractures (SOF), a cohort study of 9704 non-black women over age 65 recruited from population-based listings in four clinical centers. Using radiographs obtained at the baseline exam, we compared five methods for defining vertebral deformities: one based on a semiquantitative reading by a radiologist and four using vertebral morphometry. The semiquantitative method was compared with the other methods in a random sample of 503 films, while the morphometric methods were compared with each other in a larger sample of 9575 films. We tested a system of “triage” in which only those films with evidence of deformity were assessed by morphometry. We compared the relationship between deformity, defined by each method, and a variety of clinical criteria including bone mineral density at the lumbar spine, height loss since age 25, back pain, and incidence of subsequent deformity. Semiquantitative reading and three of the four morphometry-based methods provided similar relationships to clinical criteria. The fourth morphometry method (based on ratios of each vertebral height to the corresponding height at T4) produced significantly weaker relationships for several of the clinical validation criteria. Triage of radiographs rarely resulted in missed deformities and did not reduce the performance of any of the methods. We conclude that use of any of the similar methods, with or without triage, provides a valid approach to defining vertebral deformities.
Childhood growth, physical activity, and peak bone mass in women
Authors: Dr. Cooper Cyrus , Cawley Michael , Bhalla Ashok , Egger Peter , Ring Francis , Morton Linda , Barker David
Published: February 2010

Peak bone mass is an important determinant of the risk of osteoporotic fracture, and preventive strategies against osteoporosis require a clear understanding of the factors influencing bone gain in early life. We report a longitudinal study aiming to identify the relationships between childhood growth, lifestyle, and peak bone mass in women. One hundred and fifty-three women born in a British city during 1968–1969 were traced and studied in 1990. Data on their growth in childhood was obtained from linked birth and school health records; current bone mineral measurements were made by dual X-ray absorptiometry. There were statistically significant associations between weight at 1 year and BMC (but not BMD) at the lumbar spine (r = 0.32, p < 0.01) and femoral neck (r = 0.26, p < 0.01). These remained significant after adjusting for current weight. There were also strong relationships between childhood height measurements and adult BMC at the two skeletal sites. Physical activity was the major lifestyle determinant of BMD after allowing for body build. We conclude that infant growth and physical activity in childhood are important determinants of peak bone mass in women. Growth primarily determines the size of the skeletal envelope, and its trajectory is established by age 1 year. Activity, in contrast, modulates the mineral density within the skeletal envelope and may contribute to the consolidation of bone following the end of linear growth.
Interleukin-6 and the acute phase response during treatment of patients with paget's disease with the nitrogen-containing bisphosphonate dimethylaminohydroxypropylidene bisphosphonate
Authors: Schweitzer Dave H. , Oostendorp-van de Ruit Marjanne , van der Pluijm Gabri , Löwik Clemens W.G.M. , Dr. Papapoulos Socrates E.
Published: February 2010

Bisphosphonates suppress bone resorption and are used in the management of bone diseases with increasing frequency. In some patients treated for the first time with potent nitrogen-containing bisphosphonates, there is a transient febrile reaction and transient hematological changes suggestive of an acute phase response. Because IL-6 is considered to be an important mediator of the acute phase response, we examined the changes in circulating IL-6 bioactivity in 38 patients with Paget's disease treated with the nitrogen-containing bisphosphonate (3-dimethyl- amino-1-hydroxypropylidene)-1,1-bisphosphonate (dimethyl-APD). 16 patients who had never received such bisphosphonate were treated with oral dimethyl-APD (100–400 mg/day) and 22 (9 for the first time) with intravenous dimethyl-APD 4 mg/day. Treatment was given for 10 days. Eleven of 38 patients, all first treatments, showed an increase in body temperature of more than 0.5°C exceeding 37°C associated with a significant decrease in lymphocyte count and an increase in serum CRP values. These changes were transient and did not occur in the patients with no febrile response. In patients with a febrile reaction circulating IL-6 bioactivity increased significantly and this increase generally preceeded the rise in temperature. Moreover, patients with an acute phase response had significantly higher peak IL-6 values than those without (128 ± 30 vs. 31 ± 4 U/ml, p < 0.001). The peaks in plasma IL-6 were further correlated with the peaks in temperature and in serum CRP values (r = 0.49, p < 0.05). In vitro, low concentrations of dimethyl-APD, but not of clodronate, stimulated IL-6 release from fetal mouse bone explants and this release was markedly enhanced after treatment of the bones with dimethyl-APD followed by PTH. There was also a significant correlation between basal plasma PTH concentrations and IL-6 peaks (r = 0.60, p < 0.005) in the patients that improved further when only results from patients with first time exposure to dimethyl-APD were analyzed (r = 0.88, p < 0.002). In conclusion, an acute phase response occurred only in patients treated for the first time with the nitrogen-containing bisphosphonate dimethyl-APD and IL-6 plays a role in this response. The cellular basis of the interaction between bisphosphonates and IL-6 at the bone-bone marrow interface remains to be elucidated.
Short-term local injections of transforming growth factor-β1 decrease ovariectomy-stimulated osteoclastic resorption in vivo in rats
Authors: Beaudreuil Johann , Mbalaviele Gabriel , Cohen-Solal Martine , Morieux Caroline , de Vernejoul Marie Christine , Orcel Philippe
Published: February 2010

Estrogen deficiency in rats is responsible for increased osteoclastic resorption and a subsequent rapid bone loss. TGF-β, which is known to have acute effects on bone resorption in several in vitro models, has been shown to be secreted by osteoblastic cells in vitro in response to 17β-estradiol, but little is known about its in vivo effects on bone resorption. We therefore decided to investigate the short-term effect of TGF-β1 on bone resorption in ovariectomized rats. TGF-β1 (0.04–20 ng/injection), or vehicle, was injected daily directly into the bone marrow space, through a thin catheter implanted in the distal end of the right femur, during 4 consecutive days, starting 14 days after the ovariectomy. Bone histomorphometry was performed in the secondary spongiosa of the metaphysis of injected femurs and compared with vehicle-injected femurs of sham ovariectomized rats. Ovariectomy was associated with a marked increase in the resorption surface, a 2-fold increase in the number of osteoclasts, and no change in the number of TRAP-positive marrow cells distant from bone surfaces. Bone resorption was significantly lower in the TGF-β1-injected bones of ovariectomized rats, as compared with vehicle injected bones: the osteoclast surface and the number of osteoclasts were, respectively, 11.0 ± 5.1% versus 20.8 ± 1.3% and 287 ± 41 versus 505 ± 53, in bones injected with 0.2 ng of TGF-β1 as compared with vehicle-injected bones (mean ± SE, p < 0.05). The bone formation rate, assessed by double tetracycline labeling, was increased in ovariectomized rats, but was significantly decreased in TGF-β1-injected bones (2 and 20 ng/injection) of ovariectomized rats. The trabecular bone volume was decreased in ovariectomized animals, but was not modified in TGF-β1-injected bones in this short-term experiment. We conclude that, when injected into bones of ovariectomized rats, TGF-β1 attenuates the stimulation of osteoclastic resorption induced by estrogen deficiency. These data therefore suggest that a local failure of TGF-β secretion could be partly responsible for the stimulation of bone resorption and subsequent bone loss due to the cessation of the ovarian secretion.
Vitamin D receptor alleles and rates of bone loss: Influences of years since menopause and calcium intake
Authors: Krall Elizabeth A. , Parry Pauline , Lichter Jay B. , Dr. Dawson-Hughes Bess
Published: February 2010

A genetic marker for the 1,25-dihydroxyvitamin D receptor (VDR) is reported to account for much of the heritable component of bone density. It is not known whether VDR genotype influences bone accretion or loss, or how it is related to calcium metabolism. The VDR genotype was determined in 229 healthy postmenopausal women who previously participated in a calcium trial. VDR alleles were designated according to presence (b) or absence (B) of the BsmI restriction enzyme cutting site. There were 83 bb, 102 Bb, and 44 BB individuals. Two-thirds of the women took 500 mg of calcium supplement (mean calcium intake = 892 mg/day) and one-third a placebo (mean = 376 mg/day). Bone mineral density (BMD) at the femoral neck, spine, and radius were measured by dual- and single-photon absorptiometry at baseline and after 1 and 2 years. Among women more than 10 years postmenopausal, those with the BB genotype had the lowest femoral neck BMD. Rates of bone loss over 2 years were greater in the BB group at all sites (e.g., at the femoral neck, bb, 0.45 ± 0.43; Bb, -0.01 ± 0.40; BB, -0.99 ± 0.50%/year; BB vs. bb, p = 0.01), and this trend was found both in women <10 years since menopause (e.g., at the radius, bb, 0.43 ± 0.47; Bb, -0.37 ± 0.42; BB, -1.20 ± 0.59% per year; BB vs. bb, p = 0.02) and those ≥10 years (radius, bb, -0.71 ± 0.41; Bb, 0.08 ± 0.39; BB, -1.41 ± 0.49% per year; BB vs. Bb, p < 0.01). At the femoral neck, bone loss appeared to be modified by calcium intake (e.g., in the BB genotype: +0.03 ± 0.61 in supplemented vs. -2.01 ± 0.75%/year in placebo, in bb: 0.57 ± 0.58 vs. 0.32 ± 0.47%/year; interaction term p = 0.09), and this trend was also present in both early and late menopause. Rates of change at the radius and spine in BB were not significantly influenced by calcium at the intake levels of this study group. These results indicate that postmenopausal bone loss is influenced by the VDR genotype and suggest the adverse effect of the susceptible allele at the hip may be reduced by raising calcium intake.
The contribution of vitamin D receptor gene alleles to the determination of bone mineral density in normal and osteoporotic women
Authors: Dr. Riggs Lawrence B. , Nguyen Tijan V. , Melton Joseph L. , Morrison Nigel A. , O'Fallon William M. , Kelly Paul J. , Egan Kathleen S. , Sambrook Philip N. , Muhs Joan M. , Eisman John A.
Published: February 2010

Bone mass and its mineral content are under genetic control. The vitamin D receptor (VDR) gene has been shown to be a major locus for genetic effects on bone mineral density (BMD), and polymorphisms in this gene accounted for a large proportion of genetic variance in BMD in an Australian population. In this study, we investigated whether similar associations are present in a North American population. We studied 139 normal healthy women (age 53.2 ± 14.5, mean ± SD) and 43 severely osteoporotic postmenopausal women (age 65.8 ± 5.9). In the 127 of them with complete genetic studies, the distribution of genotypes, determined by polymerase chain reaction on leukocyte DNA samples, agreed closely with that in the Australian population. BMD was strongly related to age and weight, and, thus was adjusted for these parameters prior to genetic analysis. We found that age modulated the effect of VDR genotypes on femoral neck BMD (FN-BMD) (TaqI, p = 0.036;BsmI, p = 0.118; ApaI, p = 0.041) such that the effect of genotype was greatest among younger (premenopausal) women and declined with age so that there was no discernible difference by age 70. Among the younger women, a high FN-BMD was associated with the TT (or aa or bb) genotype while low FN-BMD was associated with the tt (or AA or BB) genotype. In osteoporotic women, although the difference in FN-BMD between alternate TaqI homozygotes (TT vs. tt) was 0.13 g/cm2 (or about 18%), the overall difference among the genotype groups was not significant (TaqI, p = 0.13; BsmI, p = 0.21; ApaI, p = 0.09), possibly due to the small sample of osteoporotic women. There was no relationship of VDR genotype to lumbar spine BMD. We conclude that the VDR gene modulates differences in BMD in premenopausal women. Subsequent interaction of the gene and environmental factors and the role of VDR genotypes in predisposing to osteoporosis needs further study.
Effects of fluoridated drinking water on bone mass and fractures: The study of osteoporotic fractures
Authors: Cauley Jane A. , Buhari Alhaji M. , Murphy Patricia A. , Riley Theodore J.
Published: February 2010

To determine if optimal fluoridation of public water supplies influences bone mass and fractures, we studied 2076 non-black women, all aged ≥65 years recruited into the Study of Osteoporotic Fractures at the Pittsburgh clinic. Information on fluoride exposure was limited to community water supplies. The variable used in the analysis was years of exposure to fluoridated water in community drinking water supplies. Bone mineral density (BMD) was measured at the spine and hip using dual energy X-ray absorptiometry and at the midpoint and ultradistal radius and calcaneus using single photon absorptiometry. Prevalent and incident vertebral fractures were determined by morphometry. Incident nonspine fractures were ascertained every 4 months and confirmed by radiographic report. Exposure to residential fluoridated water had no effect on bone mass. Women exposed to fluoride for >20 years had similar axial and appendicular bone mass to women not exposed or women exposed for ≤20 years. There was some suggestion that women exposed to fluoride for >20 years had a lower relative risk of nonspine fractures (relative risk, RR, = 0.73; 95% confidence interval [CI] 0.48–1.12), osteoporotic fractures, RR = 0.74 (CI 0.46–1.19), and hip fractures, RR = 0.44 (CI 0.10–1.86), compared with women not exposed, but none of these relative risks was statistically significant. There was no association with wrist or spinal fractures. Our results do not support the findings from recent ecological studies which showed an increased risk of hip fracture among individuals exposed to fluoridated public water. (
The effects of intravenous alendronate in Paget's disease of bone
Authors: O'Doherty D.P. , Mccloskey E.V. , Vasikaran S. , Khan S. , Kanis J.A.
Published: February 2010

We studied the effects of intravenous alendronate on disease activity in 36 patients with active Paget's disease of bone. Alendronate was administered to 3 groups of 12 patients at doses of 2.5, 5, and 10 mg intravenously daily for 5 consecutive days. The patients were matched for disease activity. Symptomatic improvement was seen in at least 10 patients in each treatment group. Alendronate induced a dose-dependent suppression of biochemical indices of bone turnover in all patients. A significant reduction in the mean fasting urinary excretion of hydroxyproline occurred within 2 days of starting treatment, reaching a nadir at 2–4 weeks, which was most marked in patients receiving 10 mg of alendronate (p < 0.05). There was a slower fall in serum alkaline phosphatase activity with maximal suppression occurring 3 months after the start of treatment. The degree of suppression was least for those receiving 2.5 mg of alendronate (p < 0.05) but no difference in response was observed for the other dosages. The duration of response was also dose-related. A significant fall in the serum calcium and urinary excretion of calcium occurred from the second day of treatment but returned to pretreatment values by 4 months. A transient fall in the mean lymphocyte count was observed, which was similar for each group. This was associated with a short-lived fever in 3 patients receiving 10 mg, in 4 patients receiving 5 mg, and in 2 patients receiving 2.5 mg. We conclude that intravenous alendronate, 5–10 mg/day for 5 days, induces a more complete suppression of bone resorption than the lower dose and provides durable long-term control of Paget's disease. (
Estimates of volumetric bone density from projectional measurements improve the discriminatory capability of dual X-ray absorptiometry
Authors: Jergas Michael , Breitenseher Martin , Glüer CLAUS-C. , Yu Wei , Genant Harry K.
Published: February 2010

To determine whether estimates of volumetric bone density from projectional scans of the lumbar spine have weaker associations with height and weight and stronger associations with prevalent vertebral fractures than standard projectional bone mineral density (BMD) and bone mineral content (BMC), we obtained posteroanterior (PA) dual X-ray absorptiometry (DXA), lateral supine DXA (Hologic QDR 2000), and quantitative computed tomography (QCT, GE 9800 scanner) in 260 postmenopausal women enrolled in two trials of treatment for osteoporosis. In 223 women, all vertebral levels, i.e., L2–L4 in the DXA scan and L1–L3 in the QCT scan, could be evaluated. Fifty-five women were diagnosed as having at least one mild fracture (age 67.9 ± 6.5 years) and 168 women did not have any fractures (age 62.3 ± 6.9 years). We derived three estimates of “volumetric bone density” from PA DXA (BMAD, BMAD*, and BMD*) and three from paired PA and lateral DXA (WA BMD, WA BMDHol, and eVBMD). While PA BMC and PA BMD were significantly correlated with height (r = 0.49 and r = 0.28) or weight (r = 0.38 and r = 037), QCT and the volumetric bone density estimates from paired PA and lateral scans were not (r = −0.083 to r = 0.050). BMAD, BMAD*, and BMD* correlated with weight but not height. The associations with vertebral fracture were stronger for QCT (odds ratio [OR] = 3.17; 95% confidence interval [CI] = 1.90–5.27), eVBMD (OR = 2.87; CI 1.80–4.57), WA BMDHol (OR = 2.86; CI 1.80–4.55) and WA-BMD (OR = 2.77; CI 1.75–4.39) than for BMAD*/BMD* (OR = 2.03; CI 132–3.12), BMAD (OR = 1.68; CI 1.14–2.48), lateral BMD (OR = 1.88; CI 1.28–2.77), standard PA BMD (OR = 1.47; CI 1.02–2.13) or PA BMC (OR = 1.22; CI 0.86–1.74). The areas under the receiver operating characteristic (ROC) curves for QCT and all estimates of volumetric BMD were significantly higher compared with standard PA BMD and PA BMC. We conclude that, like QCT, estimates of volumetric bone density from paired PA and lateral scans are unaffected by height and weight and are more strongly associated with vertebral fracture than standard PA BMD or BMC, or estimates of volumetric density that are solely based on PA DXA scans.
The effects of analytic software and scan analysis technique on the comparison of dual X-ray absorptiometry with dual photon absorptiometry of the hip in the elderly
Authors: Kiel Douglas P. , Cali Clorinda , Mercier Cherlyn A. , Dawson-Hughes Bess , Hannan Marian T. , Anderson Jennifer J.
Published: February 2010

As part of a longitudinal comparison of bone mineral density (BMD) results originally obtained using a Lunar dual photon absorptiometry (DPA) scanner and later, using a Lunar dual X-ray absorptiometry (DXA) scanner, we compared femur results between DPA and DXA according to DXA analytic software (versions 1.3y and 1.4), and according to the method of placement of the femoral neck box (software algorithm or operator placement according to the appearance of the pair of images) in 58 elderly men and women. The mean BMD at each of three femoral sites was higher using DXA version 1.3y than DPA, but the use of software version 1.4 brought the BMD value closer to that of DPA at all sites. Of 58 scans, 12 (21%) were changed by the operator, resulting in an overall reduction in mean percent BMD difference between scan pairs of 79% (from 1.24% to 0.29%). Although the differences between the DPA/DXA software-driven analysis and the DPA/DXA operator-driven analysis appeared small (high r2 values and intra-class correlation coefficients), the increase in sample size that would be required for the same power to detect 2-year changes in BMD if the software-driven analysis was used instead of taking the time to perform the operator-driven analysis was 18%. The findings of this study highlight the need to account for upgrades in analytic software. Furthermore, we present a rational approach for the analysis of serial scans that has face validity and that results in smaller differences between pairs of scans performed on the same individual. The decision to adapt these methods must be based on the relative costs of reducing unwanted scan variability.
Effect of prostaglandin E2 on phospholipase D activity in osteoblast-like MC3T3-E1 cells
Authors: Oiso Yutaka , Suzuki Atsushi , Kozawa Osamu
Published: February 2010

Recent evidence indicates that phosphatidylcholine breakdown by phospholipase D (PLD) is an important cellular control mechanism. We investigated the signaling pathway participating in prostaglandin E2 (PGE2)–induced PLD activation in osteoblast-like MC3T3-E1 cells. PGE2 stimulated PLD activity, as measured by choline generated from phosphatidylcholine, just after the stimulation. The reaction reached a plateau 15 minutes later. PGE2 stimulated PLD activity in a dose-related manner and also increased inositol phosphate (IP) formation. However, the EC50 value for PGE2-induced IP formation is lower than that for PLD activation. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC) activator, stimulated PLD activity, and a combination of PGE2 and TPA potentiated it in an additive manner. Although NaF, a heterotrimeric GTP-binding protein activator, significantly stimulated PLD activity, this effect was not augmented by combination with PGE2. PGE2-induced PLD activity was markedly suppressed by either chelating extracellular Ca2+ by EGTA or pertussis toxin. These findings suggest that osteoblasts might have at least two PLD activation mechanisms which involve PKC-dependent or -independent pathways. However, present results indicate that PKC is unlikely to be essential to PGE2-induced PLD activation. On the contrary, pertussis toxin-sensitive GTP-binding protein and extracellular Ca2+ might play important roles in the pathway of PGE2-induced PLD activation.
Intravenous pamidronate in patients with tumor-induced osteolysis: A biochemical dose-response study
Authors: Body J. J. , Dumon J. C. , Piccart M. , Ford J.
Published: February 2010

Bisphosphonates are used increasingly in normocalcemic patients for treating tumor-induced osteolysis (TIO) but little is known about the metabolic effects and the most appropriate therapeutic regimen. In 21 patients with breast cancer and TIO, we determined the biochemical effects of a single infusion of pamidronate given at 30 mg (n = 5), 60 mg (n = 5), 90 mg (n = 5), or 120 mg (n = 6). Patients received no other systemic antineoplastic therapy during the trial. We selected patients with baseline fasting urinary Ca/Creat (creatinine) >0.105 mg/mg (median value of our normal range) and they were followed weekly for up to 14 weeks. The biochemical effects were maximal at day 7. For the whole group, mean (± SEM) Ca/Creat levels fell from 0.208 ± 0.018 to 0.048 ± 0.008 mg/mg on day 7 and remained significantly (p < 0.01) lower than baseline up to day 56. Hydroxyproline excretion fell to a lesser degree, from 7.0 ± 1.2 to 4.0 ± 0.6 mg × 100/mg of Creat. The falls in Ca/Creat and hydroxyproline excretion were dose-related (ANCOVA, p < 0.05). Changes in serum parameters of calcium metabolism were, however, not significantly dose-related. Serum Ca levels fell from 9.3 ± 0.1 to 8.7 ± 0.1 mg/dl on day 7, but no patients developed symptomatic hypocalcemia, and the decrease within each dose group was significant only at 120 mg. Ca2+ levels followed a similar pattern. There was a slight increase in Mg levels and a pronounced fall in Pi levels, from 3.6 ± 0.2 to 2.8 ± 0.1 mg/dl. Intact PTH levels increased from 29 ± 4 to 91 ± 13 pg/ml and remained significantly (p < 0.05) elevated up to day 28. The concentration of 1,25(OH)2 vitamin D increased from 20 ± 2 to 45 ± 4 pg/ml, but the osteocalcin concentration did not change significantly. We subsequently treated 11 cancer patients with bone metastases and low urinary Ca/Creat levels (<0.105 mg/mg) with 30 or 60 mg of pamidronate. The changes in biochemical parameters of bone metabolism were similar to those described above, confirming the safety of these doses of pamidronate in patients without evidence of increased bone resorption. In summary, single pamidronate infusions, given at doses from 30 to 120 mg, dose-dependently inhibited bone resorption in patients with bone metastases. Pamidronate also induced marked but transient changes in blood parameters of calcium metabolism, especially at a dose of 120 mg. Our data suggest that 90 mg of pamidronate is adequate to inhibit bone resorption in this patient population.
Extracellular matrix synthesized by clonal osteogenic cells is osteoinductive in vivo and in vitro: Role of transforming growth factor-beta1 in osteoblast cell-matrix interaction
Authors: Kirk Martin D. , Kahn Arnold J.
Published: February 2010

ROB-C26 (C26) is a multipotential, clonal cell line known to express several members of the TGF-β superfamily and to become more osteoblastic (e.g., express higher levels of alkaline phosphatase) upon treatment with 10−6 M retinoic acid (RA). We hypothesize that the expression of this more osteoblastic phenotype subsequent to RA exposure is the result of the treated cell's extracellular matrix (ECM) becoming a repository and active source of putative osteoinductive growth factors including, specifically, select members of the TGF-β superfamily. To test this hypothesis, we isolated the ECM from RA-treated and untreated C26 cells and assessed them for their ability to promote osteogenic differentiation in vivo and in vitro. We then explored whether the latter activities could be attributed specifically to TGF-β1. We found that the ECM of treated cells isolated by cell lysis and extensive washing induced endochondral bone formation in vivo when implanted into the thigh muscles of athymic nude mice and stimulated alkaline phosphatase (ALP) activity in vitro in freshly plated C26 cells. This latter stimulation was comparable to levels observed with direct RA treatment. This latter in vitro activity was only very partially mimicked by the ECM prepared from untreated cells and not duplicated at all by RA-treated collagen or the ECM from another RA-treated multipotential cell line. Moreover, the in vivo osteoinductive effect of the treated C26 cell ECM was not duplicated by comparable ECM prepared from untreated cells. Finally, we also found that preincubation of the ECM with specific, neutralizing antibodies to either TGF-β's 1, 2, and 3 or TGF-β1 alone substantially reduced the ability of the ECM to stimulate ALP activity. This inhibitory effect was not seen using nonspecific IgG. These data identify the C26 cell line as a valuable model system for exploring cell-matrix interaction in osteogenic differentiation, provide direct support for an autocrine role of the ECM in such differentiation, and suggest that TGF-β1 is an important ECM-based mediator in the regulation of osteoblastic development.
A rotator cuff rupture produces permanent osteoporosis in the affected extremity, but not in those with whom shoulder function has returned to normal
Authors: Kannus Pekka , Leppälä Jari , Lehto Matti , Sievänen Harri , Heinonen Ari , Järvinen Markku
Published: February 2010

Areal bone mineral density (BMD) and clinical status of 34 men treated surgically 9 years earlier for a rotator cuff rupture of the dominant side shoulder were determined. The BMD was measured at the lumbar spine (L2–L4) and the proximal humerus, humeral shaft, radial shaft, ulnar shaft, distal forearm, and hand of both extremities using a dual-energy X-ray absorptiometric (DXA) scanner. Thirty-four age-, height-, weight-, and profession-matched normal men (controls) were also measured. The patients' mean side-to-side BMD difference (dominant minus nondominant/nondominant × 100%) was significantly lower in the proximal humerus (patients −3.5% vs. controls +2.4%, p = 0.0002), humeral shaft (–2.6% vs. +1.6%, p = 0.0005), radial shaft (–0.4% vs. +1.9%, p = 0.0311), distal forearm (–0.2% vs. +2.4%, p = 0.0158), and hand (+2.3% vs. +4.0%, p = 0.0047). In the ulnar shaft, this difference was almost the same in the patients (–0.2%) and controls (+0.2%) (NS). Also, the lumbar spine BMD did not differ significantly between these groups (mean ± SD = 1.098 ± 0.148 g/cm2 in patients vs. 1.066 ± 0.156 g/cm2 in controls). In patients, the relative BMDs of the injured extremity did not significantly associate with the size of the rupture; time delay between the injury and the surgery; type of surgery and postoperative treatment; postoperative immobilization time; follow-up time; patient's age, muscle strength or pain assessment; and subjective assessment of shoulder function. However, they strongly associated with the objective assessment of the shoulder function: the better the observed function of the shoulder, the less bone loss caused by the injury. In proximal humerus, the side-to-side BMD difference averaged +2.0% in the patient group with “excellent” shoulder function, −3.3% in the “good” group, −5.3% in the “fair” group, and −11.5% in the “poor” group (p = 0.0012).

In conclusion, a rotator cuff rupture results in permanently reduced BMD in the injured extremity, the reduction being greatest in the proximal parts of the extremity. The observed mean decreases (6% in the proximal humerus, 4% in the humeral shaft, and 3% in the distal forearm of the injured limb) are clinically important with respect to age-related bone loss of 1% per year after the age of peak bone mass. Additional follow-up is needed to determine any increased risk of osteoporotic fractures in the injured extremity. Recovery of normal shoulder function seems to be of great importance for good bone recovery.
Several anesthetics, but not diethyl ether, cause marked elevation of serum parathyroid hormone concentration in rats
Authors: Schultz V.L. , Boass A. , Garner S.C. , Toverud S.U.
Published: February 2010

The effects of anesthetics on serum parathyroid hormone (PTH) concentrations were determined by a new homologous two-site immunoradiometric assay for rat PTH. Serum PTH concentrations (mean ± SE) from ether-anesthetized rats (14.7 ± 1.5 pg/ml, n = 22) were not significantly different from those of decapitated unanesthetized female rats (13.0 ± 1.8 pg/ml, n = 21). Serum PTH concentrations in pg/ml (n = 4–14) for other anesthetics tested were: ketamine, 12.5 ± 1.1; Na pentobarbital, 23.3 ± 2.4; methoxyflurane (inhalation), 42.2 ± 6.8; and xylazine combined with ketamine, 51.4 ± 11.3 pg/ml. The latter two concentrations were significantly (p < 0.001) higher than the values for all other anesthetics and decapitation. Elevation of serum PTH induced by pentobarbital or ketamine + xylazine increased with time under anesthesia. Neither serum Ca2+ concentrations nor pH differed among any of the groups. We conclude that anesthesia induced by pentobarbital, methoxyflurane, or ketamine + xylazine in rats leads to a marked elevation of serum PTH levels that appears to be related to the duration of anesthesia and not due to any measurable fall in serum Ca2+.