bluuebunny/crossref_metadata_2025 huggingface dataset:
Small-angle x-ray scattering study of dispersed crystals from bone and tendon
Authors: Wachtel Ellen , Weiner Stephen
Published: February 2010

A small-angle x-ray scattering study of dispersed crystals from rat bone and mineralized turkey tendon shows that the particles in both preparations have the same scattering behavior. The data are very similar to those reported by Fratzl et al.(13) for intact turkey tendon and are consistent with the crystals being plate shaped. These observations have important implications for understanding both the structure and mineralization processes of these tissues.
Interaction between current smoking, leanness, and physical inactivity in the prediction of hip fracture
Authors: Forsén Lisa , Bjørndal Arild , Bjartveit Kjell , Edna Tom-Harald , Holmen Jostein , Jessen Vigleik , Westberg Gunell
Published: February 2010

To study the association between smoking habits and the incidence of hip fracture, adjusted for leanness and physical inactivity, a cohort study with 3 years follow-up was conducted. Subjects were 34,856 adults aged 50 years or older who attended a health screening in Nord-Trøndelag County in Norway in 1984–1986 (91% of eligible subjects in 1986, n = 38,356). Of these, 421 suffered a hip fracture during the years 1986–1989. Using Cox regression models, the relative risk (with 95% confidence interval) of suffering a hip fracture for female smokers versus nonsmokers was 1.5 (1.0–2.4). These results refer to females when the female body mass index (BMI) was set at 25 kg/m2 in the female model (the mean BMI for the smoking female population in this study). Among thinner females, however, smoking had a much stronger effect. For instance, if the female BMI was set at 20 kg/m2, the relative risk was 3.0 (1.8–5.0). The relative risk of hip fracture for male smokers versus nonsmokers was 1.8 (1.2–2.9) irrespective of BMI. Smoking is associated with incidence of hip fracture in both sexes and also after adjusting for body mass index and physical inactivity (the effect of physical inactivity was adjusted for self-reported ill health because ill health was included in the model). For lean females, the association with current smoking was large, as large as if they added 10 years to their age.
Monoclonal antibodies with selective reactivity against osteoblasts and osteocytes in human bone
Authors: Walsh Susan , Dodds Robert A. , James Ian E. , Bradbeer Jeremy N. , Gowen Maxine
Published: February 2010

Monoclonal antibodies (MAb) may provide valuable tools for studying osteoblast differentiation. We therefore raised a panel of MAb reactive with cells of this phenotype using 1,25(OH)2D3-treated human trabecular osteoblast-like cells (HOBS) as the immunogen. Immunohistochemical studies on various tissues, including undecalcified cryostat sections of fetal and adult human bone, identified 11 bone cell-reactive MAb. Of these, 2 demonstrated particularly selective reactivities against osteocytes (OB/M) and osteoblasts (OB/L). These reactivities were also seen in developing bone from rat, rabbit, and marmoset. OB/L and OB/M demonstrated limited reactivity against a small number of human tissues from the extensive panel of substrates tested. Both MAb exhibited reactivity against discrete populations of cells in the large and small intestine. In addition, OB/L reacted with cells in the basal epidermis of skin and OB/M with cells in blood vessel walls. Both antibodies demonstrated reactivity against a variety of cultured osteoblast-like cell lines and other cultured cell types. These MAb may therefore provide a valuable means of studying osteoblast ontogeny.
Glucocorticoid regulation of calcitonin receptor in mouse osteoclast-like multinucleated cells
Authors: Wada Seiki , Akatsu Takuhiko , Tamura Tatsuya , Takahashi Naoyuki , Suda Tatsuo , Nagata Naokazu
Published: February 2010

Abundant multinucleated cells (MNCs) are formed in cocultures of mouse osteoblastic cells and marrow cells in the presence of 1α, 25-dihydroxyvitamin D3 [1α, 25(OH)2D3], and these cells have the properties of osteoclasts (OCs). In this study using the mammalian OCs, we tried to clarify the role of glucocorticoids (GCs) in calcitonin receptors (CTR) and CT-responsive cAMP production in OCs. Dexamethasone (DEX) dose and time dependently enhanced the specific binding of [125I]salmon calcitonin (sCT). When the MNCs were preincubated with DEX for 24 h, the effect was evident at 10−9 M and the maximum effect was obtained at 10−7 M. The effect developed over 12–48 h at doses of 10−9 and 10−6 M DEX. The numbers of CTR-positive mononuclear cells and MNCs were not altered by the DEX treatment. Prednisolone and triamcinolone reproduced the DEX effect, but 17 β-estradiol, progesterone, testosterone, aldosterone, and 1α, 25(OH)2D3 did not. RU486, a GC receptor antagonist, attenuated the effect of DEX to enhance the specific binding of [125I]sCT. From a Scatchard plot analysis, DEX enhanced CTR number (212 ± 64%) with a minimal change in the affinity to sCT. Autoradiographic studies using [125I]sCT showed that DEX enhanced the density of the grains on the tartrate-resistant acid phosphatase (TRAP)-positive MNCs and mononuclear cells, but not on other types of cells. DEX preincubation also enhanced sCT-stimulated but not prostaglandin E2- or forskolin-stimulated cAMP production. Inhibition of enhancement was possible with cycloheximide, indicating this effect was mediated through de novo protein synthesis. The present study showed that GCs play an important role in the regulation of CT effect through the upregulation of CTR on OCs, and this effect would explain, at least partly, a potentiation by GCs of hypocalcemic action of CT in hypercalcemic patients.
Interactions of growth hormone and parathyroid hormone in renal phosphate, calcium, and calcitriol metabolism and bone remodeling in postmenopausal women
Authors: Lieberman Steven A. , Holloway Leah , Marcus Robert , Hoffman Andrew R.
Published: February 2010

The mechanisms underlying the effects of recombinant human growth hormone (rhGH) on vitamin D, mineral, and bone metabolism are not known. We examined whether these effects are mediated by parathyroid hormone (PTH) by measuring renal phosphorus (P) and calcium (Ca) handling, serum calcitriol, and markers of bone turnover for 24 h before and 72 h after an infusion of hPTH(1–34) in eight healthy postmenopausal women at baseline and following short-term (1 week) and sustained (5 weeks) rhGH treatment. On short-term rhGH, serum phosphorus and basal TmP/GFR were unaffected, but the fall in TmP/GFR after hPTH infusion was exaggerated (integrated response: −99.2 ± 22.3 versus −144.1 ± 15.0 minute-mg/dl, P = 0.0021). Basal calcitriol levels rose from 115 ± 17 to 163 ± 16 pM (P = 0.0002), but the increase in calcitriol following hPTH infusion was unaffected by short-term rhGH. The basal Ca excretion index (CEI) rose from 0.054 ± 0.005 to 0.073 ± 0.007 mM (P = 0.0095), but markers of bone turnover were unaffected. With sustained rhGH treatment, serum P (1.47 ± 0.05 mM), basal TmP/GFR (4.29 ± 0.24 mg/dl), and basal CEI (0.067 ± 0.005 mM) were elevated compared with control values, and the PTH-induced lowering of TmP/GFR was again enhanced (- 158.7 ± 22.8 minute-mg/dl, P = 0.0021). Basal calcitriol concentrations returned to control levels (108 ± 10 pM), but the calcitriol response to hPTH remained unchanged. Markers of bone remodeling were elevated with sustained rhGH treatment. Neither short-term nor sustained rhGH affected plasma ionized Ca, serum PTH levels, or the magnitude of the acute hydroxyproline, calcitriol, or cAMP responses to hPTH. We conclude that GH has PTH-independent effects on renal phosphate handling and 1α-hydroxylase activity, exerting its effects at a postreceptor step beyond adenylate cyclase activation.
Reduced bone mineral density in men with a previous femur fracture
Authors: Kannus Pekka , Järvinen Markku , Sievänen Harri , Järvinen Tero A. H. , Oja Pekka , Vuori Ilkka
Published: February 2010

This study determined the areal bone mineral density (BMD) from the lumbar spine (L2–4), right distal radius and ulna, and the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both extremities in 29 men who had a femur shaft fracture 10 years earlier. For evaluation of the patients' BMDs in the spine and distal forearm, 29 age-, weight-, and height-matched normal men were also measured. Compared with normal men (mean ± SD = 1.123 ± 0.153), the spinal BMDs of the patients were significantly (p = 0.0054) lower (1.018 ± 0.119, −9.3%). Distal radius and distal ulna showed no significant group differences. In patients, the mean BMD of the injured extremity (compared with the uninjured side) was significantly lower in the distal femur (-6.8%; p = 0.0000), patella (-5.4%; p = 0.0000), proximal tibia (-4.7%; p = 0.0000), and calcaneus (-2.2%; p = 0.0259). In the proximal femur, this value was at the same level (femoral neck 1.3%, NS) or higher (trochanter area 6.3%, p = 0.0002) than that in the uninjured extremity. The relative BMDs of the injured extremity did not associate with the fracture type, fracture location, age, muscle strength, follow-up time, or non-weight-bearing time but showed significant (r = 0.33–0.64) positive correlation with low pain assessment and high functional scores of the injured extremity. The relative BMDs were especially strongly associated with the four-step functional classification of the International Knee Documentation Committee: the higher the functional class of the injured extremity, the less bone loss caused by the injury (p = 0.0001–0.0328). In conclusion, the femur shaft fracture results in permanently reduced bone density in the lumbar spine and lower parts of the injured extremity. The proximal femur is not affected. The observed decrease (9% in spine and 5–7% in the knee region of the injured limb) is 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 spine and injured extremity. Recovery of normal limb function seems to be crucial for good bony recovery.
Age-associated changes in ultrasound measurements of the calcaneus in men and women: The rotterdam study
Authors: van Daele P.L.A. , Burger H. , Algra D. , Hofman A. , Grobbee D.E. , Birkenhäger J.C. , Pols H.A.P.
Published: February 2010

Broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the os calcis were measured in a sample of 1405 persons (628 men), aged 55–93 years, from the cohort of the Rotterdam Study, a population-based study of diseases in the elderly. We studied the effect of age, body mass index, age at menopause, current use of thiazides, loop diuretics, and estrogens, smoking, and disability on SOS and BUA. Comparisons were made between ultrasound measurements and bone mineral density (BMD) measurements of the lumbar spine and proximal femur using DXA. We found a significant decline with age in SOS and BUA in men (-0.4 and −0.1 %/year, respectively) and women (-1.3 and −0.4%/year, respectively), which persisted after adjustment for body mass index. Age at menopause was not associated with SOS or BUA. Pack-years of smoking was negatively related to SOS in both sexes and to BUA in men. Severe disability was associated with lower SOS and BUA in men, but not in women. Despite the small number of exposed persons, current corticosteroid use was associated with lower BUA in men. The other risk factors examined did not affect the ultrasound measurements. We observed modest correlations between SOS or BUA, on the one hand, and BMD of the lumbar spine, on the other hand (r = 0.32–0.42). Similar correlations were found between ultrasound measurements and BMD measurements of the proximal femur. We conclude that in persons 55 years or over (1) there is a significant age-related decline of BUA and SOS, which is about three times higher in women compared with men, and (2) ultrasound measurements are not able to predict low BMD in hip or spine.
Alendronate increases skeletal mass of growing rats during unloading by inhibiting resorption of calcified cartilage
Authors: Bikle Daniel D. , Morey-Holton Emily R. , Doty Stephen B. , Currier Patricia A. , Tanner Sharon J. , Halloran Bernard P.
Published: February 2010

Loss of bone mass during periods of skeletal unloading remains an important clinical problem. To determine the extent to which resorption contributes to the relative loss of bone during skeletal unloading of the growing rat and to explore potential means of preventing such bone loss, 0.1 mg P/kg alendronate was administered to rats before unloading of the hindquarters. Skeletal unloading markedly reduced the normal increase in tibial mass and calcium content during the 9 day period of observation, primarily by decreasing bone formation, although bone resorption was also modestly stimulated. Alendronate not only prevented the relative loss of skeletal mass during unloading but led to a dramatic increase in calcified tissue in the proximal tibia compared with the vehicle-treated unloaded or normally loaded controls. Bone formation, however, assessed both by tetracycline labeling and by [3H]proline and 45Ca incorporation, was suppressed by alendronate treatment and further decreased by skeletal unloading. Total osteoclast number increased in alendronate-treated animals, but values were similar to those in controls when corrected for the increased bone area. However, the osteoclasts had poorly developed brush borders and appeared not to engage the bone surface when examined at the ultrastructural level. We conclude that alendronate prevents the relative loss of mineralized tissue in growing rats subjected to skeletal unloading, but it does so primarily by inhibiting the resorption of the primary and secondary spongiosa, leading to altered bone modeling in the metaphysis.
Bone mineral density at distal tibia using dual-energy x-ray absorptiometry in normal women and in patients with vertebral osteoporosis or primary hyperparathyroidism
Authors: Casez J.-P. , Troendle A. , Lippuner K. , Jaeger P.
Published: February 2010

To assess the effect of age and disease on mineral distribution at the distal third of the tibia, bone mineral content (BMC) and bone mineral density (BMD) were measured at lumbar spine (spine), femoral neck (neck), and diaphysis (Dia) and distal epiphysis (Epi) of the tibia in 89 healthy control women of different age groups (20-29, n = 12; 30-39, n = 11; 40-44, n = 12; 45-49, n = 12; 50-54, n = 12; 55-59, n = 10; 60-69, n = 11; 70-79, n = 9), in 25 women with untreated vertebral osteoporosis (VOP), and in 19 women with primary hyperparathyroidism (PHPT) using dual-energy x-ray absorptiometry (DXA; Hologic QDR 1000 and standard spine software). A soft tissue simulator was used to compensate for heterogeneity of soft tissue thickness around the leg. Tibia was scanned over a length of 130 mm from the ankle joint, fibula being excluded from analysis. For BMC and BMD, 10 sections 13 mm each were analyzed separately and then pooled to define the epiphysis (Epi 13-52 mm) and diaphysis area (Dia 91-130 mm). Precision after repositioning was 1.9 and 2.1% for Epi and Dia, respectively. In the control group, at any site there was no significant difference between age groups 20-29 and 30-39, which thus were pooled to define the peak bone mass (PBM). Mean decrease in BMD from PBM (mean + SEM) was significant after age 49 at Epi (-11.8 + 12.7%), after age 54 at spine (-14.2 + 5.9%) and neck (-11.2 + 8.6%), and after age 59 at Dia (-10.9 + 6.9%). Epiphysis and diaphysis BMC but not BMD were correlated with body weight (r = 0.22, p < 0.04 for both sites). In patients with PHPT mean tibial BMD expressed as Z scores was significantly lower than in controls, from 39 to 130 mm but was similar to that in controls from 0 to 39 mm as well as at spine and neck. In patients with untreated VOP, mean BMD (Z scores) was lower than in controls at spine and neck as well as tibia from 0 to 52 mm (p < 0.01) but not between 52 and 130 mm. We conclude that DXA measurement at tibia is a suitable tool to assess bone loss and distribution of bone mass between Dia (cortical) and Epi (with a substantial amount of trabecular bone) in a single weight-bearing bone in health and bone diseases.
Osteoporosis in african hemosiderosis: Role of alcohol and iron
Authors: Schnitzler Christine M. , Macphail A. Patrick , Shires Roy , Schnaid Edward , Mesquita Julia M. , Robson Heather J.
Published: February 2010

This paper aims to examine the relative contributions made by alcohol and iron overload and hypovitaminosis C to the osteoporosis associated with African hemosiderosis. To characterize this bone disorder, we examined double-tetracycline-labeled iliac crest bone biopsies and serum biochemistry in 53 black male drinkers, 38 with (Fe+) and 15 without (Fe−) iron overload, and in controls. We reasoned that abnormalities found in both patient groups were likely to be caused by alcohol abuse and those found only in the Fe+ group to be caused by iron overload and hypovitaminosis C (iron/C−). The patient groups differed only with respect to greater erosion depth (p < 0.05) and abnormal markers of iron overload in the Fe+ group. Ascorbic acid levels were lower in the Fe+ group than in controls (p < 0.001). Bone volume and trabecular thickness were significantly lower in both patient groups compared with controls and therefore likely caused by alcohol. There were no positive correlations between formation and erosion variables in either patient group, which suggests uncoupling of formation from erosion, possibly as a result of alcohol abuse. Prolonged mineralization lag time associated with thin osteoid seams was found in 32% of patients, affecting both groups. This rules out osteomalacia and suggests osteoblast dysfunction, probably caused by alcohol. The number of iron granules in the marrow correlated with erosion depth (r = 0.373, p < 0.01), trabecular number (r = -0.295, p < 0.05), and trabecular separation (r = 0.347, p < 0.05). Abnormalities in these variables were therefore attributed mainly to iron/C−. Several formation variables were significantly directly correlated with indicators of iron overload, suggesting that iron/C− does not adversely affect bone formation. We conclude that alcohol abuse was predominantly associated with thinning of trabeculae and iron overload and hypovitaminosis C with increased erosion depth and disconnection of the trabecular network. Osteomalacia was not seen.
Trochanteric bone mineral density is associated with type of hip fracture in the elderly
Authors: Greenspan Susan L. , Myers Elizabeth R. , Maitland Lauri A. , Kido Tamiko H. , Krasnow Meryl B. , Hayes Wilson C.
Published: February 2010

Hip fractures can be separated into femoral neck (cervical or intracapsular) or trochanteric (extracapsular). Trochanteric fractures have been associated with up to twice the short-term mortality of cervical fractures in the elderly. Fracture type may be influenced by the fall direction and local differences in proximal femur strength properties. We previously demonstrated that fall characteristics and body habitus, in addition to femoral bone mineral density, play a dominant role in the prediction of hip fracture in elderly fallers. To examine the association of these determinants with hip fracture type, we assessed fall characteristics, body habitus, and site-specific bone mineral density measurements in 112 elderly hip fracture patients (85 women and 27 men, mean age 85 years) 1 week after an acute hip fracture. Trochanteric BMD was 13% lower in women and 11% lower in men for patients with trochanteric fracture than in those with femoral neck fracture (p < 0.01). A stepwise multiple logistic regression indicated that trochanteric BMD (decrease of 1.0 SD, adjusted OR 4.6, 95% CI 2.0-9.5, p < 0.0001) and femoral neck BMD (increase of 1.0 SD, adjusted OR 3.0, 95% CI 1.6-5.9, p = 0.0003) were independently associated with trochanteric fracture. Fall characteristics, body habitus, gender, and age were not associated with hip fracture type. We conclude that a relatively low trochanteric BMD or a high femoral neck BMD was associated with a trochanteric hip fracture and that site-specific trochanteric BMD determinations should be measured when assessing risk of trochanteric hip fractures in the elderly.
Variation in vertebral height ratios in population studies
Authors: O'Neill T.W. , Varlow J. , Felsenberg D. , Johnell O. , Weber K. , Marchant F. , Delmas P.D. , Cooper C. , Kanis J. , Silman A.J. ,   European Vertebral Osteoporosis Study Group
Published: February 2010

Vertebral height ratios are used to define vertebral deformity in clinical and epidemiologic studies of vertebral osteoporosis. However, few data have been obtained on the variation in these ratios in different populations using standard methods. We examined vertebral morphometric measurements obtained in a population survey from three centers: Malmö (Sweden), Montceau-les-Mines (France), and Graz (Austria), to study the influence of sex and the population center on vertebral height ratios. Radiographs were obtained according to a standardized protocol, and morphometric measurements, anterior height Ha, central height Hc, and posterior height Hp, made in Berlin. The height ratios anterior, Ha/Hp, central, Hc/Hp, posterior I, Hp/Hp', and posterior II, Hp/Hp″ (Hp' = posterior height of vertebrae above, Hp″ = posterior height of vertebrae below) were calculated for each vertebra from T4 to L4. The mean and standard deviation of these ratios for each sex and each center were derived using a statistical trimming procedure to normalize the distribution. Threshold values for defining grade 1 and grade 2 deformities, wedge, biconcavity, and compression, were calculated using these parameters. Anterior and central vertebral height ratios were smaller in males than females (p < 0.01). There were significant differences between the three centers (p < 0.01) both in the trimmed mean values for anterior and central vertebral height ratios and in the thresholds derived using standard criteria for defining wedge and biconcavity deformity. The data confirm the impression from single-center studies that vertebral height ratios vary between populations and suggest that reference values for vertebral height ratios should be derived separately for males and females within individual populations whenever possible.
Inhibition of collagen synthesis by prostaglandins in the immortalized rat osteoblastic cell line pyla: Structure-activity relations and signal transduction mechanisms
Authors: Fall Pamela M. , Breault David T. , Raisz Lawrence G.
Published: February 2010

We previously showed that prostaglandin E2 (PGE2) can selectively inhibit collagen synthesis and gene transcription in the immortalized rat osteoblastic clonal cell line Py1a, particularly in the presence of insulin-like growth factor I (IGF-I). In the present study, we examined the structure-activity relations for this effect. PGF2α was approximately 100 times more potent than PGE2. The prostaglandin F receptor (FP) selective agonist, fluprostenol, was the most potent agonist tested, significantly inhibiting incorporation of [3H]proline into both collagen and noncollagen protein at 10−11 M, with more than 90% inhibition of collagen synthesis at 10−8 M. The PGE2 analog, sulprostone, and PGD2 showed activity similar to that of PGE2. PGI2 and its stable analog, carbacyclin, were the least effective. Parathyroid hormone (PTH), forskolin, and isobutylmethylxanthine (IBMX) were ineffective. Phorbol myristate acetate (PMA) inhibited collagen synthesis in a manner similar to that of the prostanoids. The inhibitory effects of PGF2α, fluprostenol, and PMA show a similar time course on α1 (I) procollagen mRNA levels. The inhibition appeared to be caused by a decrease in collagen gene transcription as measured by nuclear run-on analysis. Further evidence for a transcriptional effect was obtained with COLIA1 promoter-CAT reporter constructs, although these showed somewhat smaller effects of prostanoids on CAT activity than on mRNA levels or labeling. Based on these results, we conclude that in the Py1a cell line prostanoids inhibit collagen synthesis by a pathway involving activation of protein kinase C that is not dependent on adenylate cyclase. The structure-activity relations for this response suggest that it is mediated by an FP receptor and is distinctly different from the stimulatory effects on bone resorption and formation.
Activation of the human osteocalcin gene by 24r,25-dihydroxyvitamin d3 occurs through the vitamin d receptor and the vitamin d-responsive element
Authors: Uchida Motoyuki , Ozono Keiichi , Pike Wesley J.
Published: February 2010

1α-25-dihydroxyvitamin D3 [1α,25(OH)2D3], together with vitamin D receptor (VDR), directly activates human osteocalcin (hOC) gene expression through a vitamin D-responsive element (VDRE) located in the promoter of the hOC gene. We investigated the effect of 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] on the regulation of the hOC gene promoter and compared it with that of α,25(OH)2D3. 24R,25(OH)2D3 did not activate the natural promoter in VDR-negative CV-1 cells. 24R,25(OH)2D3, however, induced the activation of this promoter following cotransfection with an hVDR expression vector. In VDR-positive MC3T3-E1 cells, 24R,25(OH)2D3 activated not only the natural hOC promoter but also a chimeric promoter composed of a synthetic hOC VDRE sequence linked to the thymidine kinase promoter. In combination with 1α-25(OH)2D3, 24R,25(OH)2D3 did not exhibit any antagonist activity on the hOC promoter. These results suggest that under conditions of high 24R,25(OH)2D3 levels in vivo, this metabolite of vitamin D3 may activate hOC gene expression through receptor mechanisms identical to that for 1α,25(OH)2D3.
Skeletal response to recombinant human growth hormone (rhGH) in children treated with long-term corticosteroids
Authors: Sanchez Cheryl P. , Goodman William G. , Brandli David , Goldenhersh Margaret , Murray Carol , Carlton Esther , Hahn Theodore , Salusky Isidro B.
Published: February 2010

Corticosteroid therapy causes osteopenia and growth retardation in children; such changes are associated with diminished rates of bone formation and turnover. Since growth hormone activates bone remodeling, the biochemical and skeletal responses to rhGH were evaluated in four pediatric patients, aged 12.8 ± 3 years, with long-term corticosteroid use (5 ± 2 years). Recombinant human growth hormone (rhGH), 0.125 mg/kg, was given 3 times/week by subcutaneous injection for 12 months. Iliac crest bone biopsies were obtained after double tetracycline labeling before and at the end of rhGH therapy; serum levels of calcium, phosphorus, alkaline phosphatase, parathyroid hormone (intact), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D3, osteocalcin (BGP), and insulin-like growth factor-1 (IGF-1) were measured every 3 months during the treatment period. The average dose of prednisone was 0.24 ± 0.05 mg/kg/day initially, and this did not change during the study. Serum calcium, phosphorus, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D3, and BGP were unchanged during the rhGH therapy, but the serum IGF-1 level increased by 71%, p < 0.01. Eroded bone perimeter and cancellous bone area did not change significantly during rhGH therapy. Bone formation rates rose from 423 ± 475 to 781 ± 407 μm2/mm2/day, p < 0.05, and the length of double tetracycline-labeled bone perimeter increased by 85%, p < 0.05. The bone formation rate in the growth hormone group exceeded the values of an age-matched reference group (143 ± 3 years), 780 ± 407 μm2/mm2/day versus 411 ± 479 μ m2/mm2/day, p < 0.05. Thus, rhGH therapy increases osteoblastic activity, bone formation, and possibly bone turnover despite continued and prolonged corticosteroid administration in children.
Expression and secretion of parathyroid hormone-related protein by human bone-derived cells in vitro: Effects of glucocorticoids
Authors: Walsh C.A. , Birch M.A. , Fraser W.D. , Lawton R. , Dorgan J. , Walsh S. , Sansom D. , Beresford J.N. , Gallagher J.A.
Published: February 2010

We investigated the production of parathyroid hormone-related protein (PTHrP) by cells derived from explants of human bone. Using an immunoradiometric assay (IRMA), PTHrP was detected in conditioned medium from cultures of bone-derived cells from 6 of 7 patients investigated in this study. PTHrP mRNA was identified in human bone cells using reverse transcriptase-linked polymerase chain reaction (RT-PCR) and by Northern analysis. Transcripts for PTHrP were detected in a purified population of alkaline phosphatase positive cells isolated from human bone marrow cultures by flow cytometry, confirming the expression of PTHrP mRNA by cells of the osteoblastic lineage. Production of PTHrP was inhibited by 10−6 M of the glucocorticoids, prednisolone and desacetylated deflazacort, in a dose-dependent manner. In addition, RT-PCR followed by Southern blot analysis detected a decrease in steady-state PTHrP mRNA in cultures of human bone-derived cells treated with 10−6 M prednisolone.
In vivo evidence for progressive activation of parathyroid hormone-related peptide gene transcription with tumor growth and stimulation of osteoblastic bone formation at an early stage of humoral hypercalcemia of cancer
Authors: Yamato Hideyuki , Nagai Yumiko , Inoue Daisuke , Ohnishi Yasuyuki , Ueyama Yoshito , Ohno Hideto , Matsumoto Toshio , Ogata Etsuro , Ikeda Kyoji
Published: February 2010

The present study was undertaken to clarify in vivo the temporal profile of parathyroid hormone-related peptide (PTHRP) gene expression as well as bone histomorphometric features as a function of tumor growth, using an athymic rat model associated with humoral hypercalcemia of malignancy (HHM). Tumor-bearing animals exhibited hypercalcemia, hypophosphatemia, and increased circulating levels of PTHRP, and died within 3 weeks. Steady-state PTHRP mRNA levels and the transcription rate of PTHRP gene in the tumors were markedly increased with tumor growth. RNAse mapping analysis revealed that both upstream and downstream promoters of the human PTHRP gene were utilized in the tumors and became progressively activated with time. Bone histomorphometric analysis showed that osteoclastic bone resorption was progressively increased throughout the course, whereas osteoblastic bone formation was stimulated more than 2-fold at a very early stage (day 6 after tumor implantation) and then markedly suppressed thereafter on day 12 and day 18 compared with age-matched control animals. These results provide in vivo evidence that PTHRP gene transcription is progressively activated with tumor growth and that activation of osteoblasts does occur at a very early phase of HHM syndrome in contrast to the marked suppression of bone formation at later stages.
Calcitonin receptor isoforms in mouse and rat osteoclasts
Authors: Ikegame Mika , Rakopoulos Maryann , Zhou Hong , Houssami Souheir , Martin John T. , Moseley Jane M. , Findlay David M.
Published: February 2010

Calcitonin receptors (CTRs) from several species have recently been cloned and shown to belong to the 7 transmembrane domain class of receptor. We have identified two CTR isoforms in the rat, termed C1a and C1b, identical except for a 37-amino-acid insert in the putative second extracellular domain of C1b. To examine the CTR isoforms expressed in rat and mouse osteoclasts and the time course of their appearance in culture, bone marrow cells were cultured from C57/B16J mice and osteoclasts were isolated from newborn rat long bones. CTR-bearing cells were detected by autoradiography of 125I-salmon CT binding, and cultures were stained for tartrate-resistant acid phosphatase (TRAP). RNA was extracted from parallel cultures, and CTR mRNA was detected by Northern blot analysis, using a rat digoxigenin-labeled riboprobe. Characterization of mRNA for the CTR isoforms was by reverse transcription-polymerase chain reaction (RT-PCR) using primer sets and oligonucleotide probes specific for the two rat receptor isoforms. In mouse marrow cultures, TRAP positive mononucleated cells were present by day 2 of culture at which time CTR positive cells were few. Multinucleated cells with both these markers were seen only from day 4 and later. By Northern analysis of total RNA, a band of approximately 4 kb could be detected in day 4 and later cultures. RT-PCR showed that mouse homologs of both C1a and C1b mRNA species were expressed early in cultures of mouse osteoclasts, although at each time C1a appeared to predominate. RNA was also extracted from osteoclasts freshly isolated from neonatal rat long bone osteoclasts. Northern blot analysis suggested that these preparations contained less CTR mRNA than the developing mouse osteoclast preparations. RT-PCR indicated that both receptor isoforms were expressed in rat osteoclasts.
Thiazide diuretics and fractures: Can meta-analysis help?
Authors: Dr. Menzies G. Jones , Nguyen Tuan , Sambrook Philip N. , Eisman John A.
Published: February 2010

Published observational estimates of the effect of thiazide diuretics on osteoporotic fracture risk vary from a 70% reduction to a 60% increase but there have been no randomized controlled trials. The aims of this study were to use the technique of meta-analysis to attempt to resolve this conflict and to explore whether duration and/or dose of therapy has an effect on osteoporotic fracture risk. The data sources utilized were Medline and Excerpta Medica databases supplemented by reviews and back references. A total of 18 observational studies that looked at the relationship between diuretics and fracture were located, of which 13, involving 29,600 subjects, had extractable data on thiazides and fracture occurrence. Current thiazide users were protected against hip fracture (OR 0.82, 95% Cl 0.73–0.91). Thiazide use of long duration may be protective (OR 0.82, 95% Cl 0.62–1.08) but not short duration (OR 1.23, 95% Cl 0.99–1.54). The size of this effect, which compares favorably to other interventions, indicates that a randomized controlled trial to resolve the problem of potential confounders and safety profile would require a minimum of 7000 person-years of observation in those at highest risk of fracture (women aged 80 or over) which is unlikely to be pursued at the present time. The results of this meta-analysis indicate that current thiazide users have a 20% reduction in fracture risk and that long-term use may reduce fractures by a similar amount These results suggest, in the absence of a suitably designed large randomized controlled trial, that thiazides should be considered as part of an approach to osteoporotic fracture prevention, particularly in hypertensive subjects.
Estimation of structural and geometrical properties of cortical bone by computerized tomography in 78-year-old women
Authors: Cheng Sulin , Toivanen Jari Antero , Suominen Harri , Toivanen Jarmo Tapani , Timonen Jussi
Published: February 2010

The structural and geometrical properties of the tibia shaft were investigated at two sections by means of computerized tomography (CT) in 78-year-old women with high (n = 19) and low (n = 17) calcaneal bone mineral density (BMD, g/cm3) previously measured by 125I-photon absorption. The high BMD group had a 20–21% higher tibial BMD and 9–12% higher bone cross-sectional area than was observed in the low BMD group. The distribution of bone mass indicated that the low BMD group had lost bone mainly from the endosteal surface, especially in the anterior part of the tibia. However, both groups had a similar basic pattern of mass distribution at the measured sections. The high BMD group had higher moments of inertia at the upper section than the low BMD group. The differences between the groups were more pronounced when only the high density areas were included. At the lower section, the differences between the groups also appeared significant at the high density levels. There were no group differences in the area moments of inertia. The results suggest that the true distribution of bone mass should be taken into account in determining the moments of inertia. In the tibia, determination of the cross-sectional mass distribution of bone combined with BMD should have a better discriminatory capability than BMD only in studying bone strength and fracture risk.
Risk factors for renal osteodystrophy: A multivariant analysis
Authors: Pei York , Hercz Gavril , Greenwood Celia , Segre Gino , Manuel Arif , Saiphoo Carl , Fenton Stanley , Sherrard Donald
Published: February 2010

To assess the risk factors associated with renal osteodystrophy, we examined the database of 256 patients who were prospectively studied in three Toronto dialysis centers between October of 1987 and 1989. The potential risk factors examined included age, sex, type and duration of dialysis, type and dose of phosphate binders, vitamin D treatment, and history of diabetes mellitus, renal allograft failure, parathyroidectomy, and bilateral nephrectomy. All patients had undergone a bone biopsy and were categorized into one of four disease groupings: (1) osteitis fibrosa and mixed bone disease, (2) aluminum bone disease, (3) mild bone disorder, and (4) aplastic bone disorder. The mean (±SD) age of the patients at bone biopsy was 57 ± 15 years, and 62% were men. Forty-five percent of patients were treated by hemodialysis and 55% by peritoneal dialysis. The mean duration of dialysis was 4 ± 4 years. Twenty-five percent were also diabetic. The most common disorder was the aplastic (or “adynamic”) bone disorder, found in 34% of patients. Aluminum bone disease was found in 27%, osteitis fibrosa or mixed bone disease in 27%, and mild bone disorder in 12% of patients. Cumulative intake of aluminum gels was associated with aluminum bone disease, whereas peritoneal dialysis with supraphysiologic calcium concentrations, ingestion of calcium carbonate, and diabetes mellitus were associated with both mild bone disorder and aplastic bone disorder. These three latter risk factors may be important in predisposing patients to a low bone turnover state through modulation of parathyroid hormone secretion. Thus, recent increases in the frequencies of these risk factors in dialysis patients are associated with a high prevalence of aplastic bone disorder. The clinical significance of this bone disorder remains to be defined.
Characterization of structural sequences in the chicken osteocalcin gene: Expression of osteocalcin by maturing osteoblasts and by hypertrophic chondrocytes in vitro
Authors: Neugebauer Brigitte M. , Moore Mark A. , Broess Martin , Dr. Gerstenfeld L.C. , Dr. Hauschka P.V.
Published: February 2010

Osteocalcin is one of the major noncollagenous proteins specific to mineralized connective tissues of vertebrates. A cDNA clone encoding the chicken osteocalcin gene was isolated, and the complete coding sequence for the 97-amino-acid pre-pro-osteocalcin was deduced. The 48-amino-acid pre-pro-peptide contains the expected hydrophobic leader sequence and the dibasic Lys-Arg sequence preceding the NH2-terminal His of the mature 49-amino-acid chicken osteocalcin, which is believed to be necessary for pro-peptide cleavage. The pro-peptide sequence also contains the expected motif of polar and hydrophobic residues, including Phe at −16, which targets vitamin K-dependent γ-carboxylation of the three specific Glu residues at positions 17, 21, and 24 in the mature protein. Northern blots of total RNA were prepared from embryonic and adult chicken tissues (bone, brain, heart, intestine, kidney, muscle) and probed with chicken osteocalcin cDNA. The appearance of a single 0.5 kb mRNA species confirms that bone is the major site of osteocalcin expression in vivo. In primary osteoblasts isolated from 17-day embryonic chicken calvaria, an osteocalcin mRNA of similar size is expressed concurrently with culture mineralization in vitro. Hypertrophic chondrocytes from 12-day ventral vertebrae and from the cephalic half of 17-day caudal sternae also express osteocalcin mRNA, but nonhypertrophic chondrocytes from the caudal half of 17-day sternae do not express osteocalcin mRNA.
Fluoride increases tyrosine kinase activity in osteoblast-like cells: Regulatory role for the stimulation of cell proliferation and Pi transport across the plasma membrane
Authors: Burgener D. , Bonjour J.-P. , Dr. Caverzasio Joseph
Published: February 2010

Fluoride is one of the most effective agents for the treatment of vertebral osteoporosis because of its ability to increase osteoblast proliferation. The present study further investigates the role of protein tyrosine phosphorylation previously suggested to mediate the mitogenic effect of fluoride on bone-forming cells. The activity of the plasma membrane Na-coupled Pi transport system was monitored to assess the relationship between alterations in tyrosine phosphorylation and osteoblast activity induced by fluoride. The results indicate that vanadate, a selective inhibitor of tyrosine phosphatase, mimicked the stimulatory effect of fluoride on Pi transport. The change in Pi transport induced by fluoride was dose dependently inhibited by genistein, a potent inhibitor of tyrosine kinase. Genistein also inhibited the change in cell proliferation induced by fluoride. Associated with these observations, tyrosine phosphorylation activity was significantly increased in subcellular fractions isolated from UMR-106 cells treated with fluoride as compared with those isolated from vehicle-treated cells. This change in tyrosine phosphorylation activity was markedly blunted when genistein was added to the kinase assay buffer. It was not associated with any alteration in specific tyrosine phosphatase activity. There was also no evidence of a direct effect of fluoride on tyrosine phosphatase activity in isolated plasma membrane of UMR-106 cells. In conclusion, the results of the present study suggest that fluoride enhances protein tyrosine phosphorylation in osteoblast-like cells by enhancing tyrosine kinase activity. The results further support the hypothesis that this signal transduction mechanism is involved in the osteogenic effects of fluoride.
Development and characterization of a conditionally immortalized human fetal osteoblastic cell line
Authors: Dr. Harris Steven A. , Enger Robert J. , Riggs Lawrence B. , Spelsberg Thomas C.
Published: February 2010

We report the establishment of a human fetal osteoblast cell line derived from biopsies obtained from a spontaneous miscarriage. Primary cultures isolated from fetal tissue were transfected with a gene coding for a temperature-sensitive mutant (tsA58) of SV40 large T antigen along with a gene coding for neomycin (G418) resistance. Individual neomycin resistant colonies were screened for alkaline phosphatase (AP)-specific staining. The clone with the highest AP level, hFOB 1.19, was examined further for other osteoblast phenotypic markers. Incubation of hFOB cells at the permissive temperature (33.5°C) resulted in rapid cell division, whereas little or no cell division occurred at the restrictive temperature (39.5°C). Both AP activity and osteocalcin (OC) secretion increased in a dose-dependent manner following dihydroxyvitamin D3 (1,25-D3) treatment when cultured at either temperature. However, AP and 1,25-D3-induced OC levels were elevated in confluent hFOB cells cultured at 39.5°C compared with 33.5°C. Treatment of hFOB cells with 1–34 parathyroid hormone (PTH) resulted in an increase in cAMP levels. Upon reaching confluence, hFOB cultures went through programmed differentiation and formed mineralized nodules as observed by von Kossa staining. Further, immunostaining of postconfluent, differentiated hFOB cells showed that high levels of osteopontin, osteonectin, bone sialoprotein, and type I collagen were expressed. Therefore, the clonal cell line hFOB 1.19 provides a homogeneous, rapidly proliferating model system to study certain stages of human osteoblast differentiation.
Effects of 24r,25-dihydroxyvitamin D3 in combination with 1α-hydroxyvitamin D3 in predialysis renal insufficiency: Biochemistry and histomorphometry of cancellous bone
Authors: Birkenhäger-Frenkel D.H. , Pols H.A.P. , Zeelenberg J. , Eijgelsheim J.J. , Schot R. , Nigg A.L. , Weimar W. , Mulder P.G.H. , Birkenhäger J.C.
Published: February 2010

The effect of combined administration of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3) and 1α-hydroxyvitamin D3 (1α-(OH)D3) was studied in 24 non-dialyzed patients with chronic renal insufficiency (CRI), matched pair-wise as to age, sex, and creatinine clearance (Cr.cl). Low Ca intake had been supplemented beforehand. Then, 1α-(OH)D3 (mean dose 0.55 μg daily) was given orally to all patients for 3 months (T0 to T3). Subsequently, patients were assigned randomly to 6 months further treatment either with 1α-(OH)D3 alone (Group A) or with 1α-(OH)D3 plus a high dosage of 24,25-(OH)2D3 (50 μg orally, twice weekly) (Group B). Histomorphometry was performed at T0T3, and T9. In both groups iPTH was equally suppressed, into the lower normal range. Whereas in Group A, serum Ca rose steadily and Cr.cl declined, in Group B both parameters levelled off between T6 and T9. At T9, in Group A the elevated resorption and osteoid indices had normalized markedly, but osteoblasts (Ob.Pm) and mineralizing boundaries (M.Bd) were depressed considerably between T3 and T9. In contrast, in Group B, preservation of Ob.Pm and improved mineralizing activity were observed (M.Bd at T9 > T3 > T0). Resorption indices hardly changed. In the patients with high Ob.Pm at T0, cancellous bone area increased significantly. This was not observed in Group A. Thus, in Group B, osteoblast recruitment appeared maintained and M.Bd appeared normalized. Decline of remodeling toward an adynamic state with an increased risk of hypercalcemia appeared prevented.
Spontaneous postmenopausal bone loss in different skeletal areas—followed up for 15 years
Authors: Hansen M.A. , Overgaard K. , Christiansen C.
Published: February 2010

We examined the spontaneous bone loss in two populations of healthy postmenopausal women, who were followed for 9.5 and 14.5 years without any treatment influencing the calcium metabolism. The bone mass was measured in different skeletal areas: the distal forearm, the lumbar spine, the proximal femur, and the total skeleton. The spontaneous bone loss in the distal forearm, the lumbar spine, and the total skeleton was fitted to an exponential model as a function of years since menopause. The overall bone loss averaged 20–25% of premenopausal bone mass 16 years after menopause. The patterns of bone loss were, however, different for the axial and the peripheral skeleton. Thus, the bone loss in the distal forearm approached a more linear model with a more consistent bone loss throughout the observation period. In contrast, the lumbar spine showed no significant loss 8 years after menopause. This arrest in bone loss could not be explained by the presence of degenerative changes in the lumbar spine and/or aortic calcifications, although these changes significantly contributed to 14% increased bone mineral density (p < 0.001). We conclude that bone loss averages 20–25% over the initial 16 years of menopause regardless of skeletal site and that patterns of bone loss are different in the axial and peripheral skeleton.