Showing papers in "Journal of Bone and Mineral Research in 2005"

Predictive Value of BMD for Hip and Other Fractures

Abstract: The relationship between BMD and fracture risk was estimated in a meta-analysis of data from 12 cohort studies of approximately 39,000 men and women. Low hip BMD was an important predictor of fracture risk. The prediction of hip fracture with hip BMD also depended on age and z score. INTRODUCTION: The aim of this study was to quantify the relationship between BMD and fracture risk and examine the effect of age, sex, time since measurement, and initial BMD value. MATERIALS AND METHODS: We studied 9891 men and 29,082 women from 12 cohorts comprising EVOS/EPOS, EPIDOS, OFELY, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, DOES, Hiroshima, and 2 cohorts from Gothenburg. Cohorts were followed for up to 16.3 years and a total of 168,366 person-years. The effect of BMD on fracture risk was examined using a Poisson model in each cohort and each sex separately. Results of the different studies were then merged using weighted coefficients. RESULTS: BMD measurement at the femoral neck with DXA was a strong predictor of hip fractures both in men and women with a similar predictive ability. At the age of 65 years, risk ratio increased by 2.94 (95% CI = 2.02-4.27) in men and by 2.88 (95% CI = 2.31-3.59) in women for each SD decrease in BMD. However, the effect was dependent on age, with a significantly higher gradient of risk at age 50 years than at age 80 years. Although the gradient of hip fracture risk decreased with age, the absolute risk still rose markedly with age. For any fracture and for any osteoporotic fracture, the gradient of risk was lower than for hip fractures. At the age of 65 years, the risk of osteoporotic fractures increased in men by 1.41 per SD decrease in BMD (95% CI = 1.33-1.51) and in women by 1.38 per SD (95% CI = 1.28-1.48). In contrast with hip fracture risk, the gradient of risk increased with age. For the prediction of any osteoporotic fracture (and any fracture), there was a higher gradient of risk the lower the BMD. At a z score of -4 SD, the risk gradient was 2.10 per SD (95% CI = 1.63-2.71) and at a z score of -1 SD, the risk was 1.73 per SD (95% CI = 1.59-1.89) in men and women combined. A similar but less pronounced and nonsignificant effect was observed for hip fractures. Data for ultrasound and peripheral measurements were available from three cohorts. The predictive ability of these devices was somewhat less than that of DXA measurements at the femoral neck by age, sex, and BMD value. CONCLUSIONS: We conclude that BMD is a risk factor for fracture of substantial importance and is similar in both sexes. Its validation on an international basis permits its use in case finding strategies. Its use should, however, take account of the variations in predictive value with age and BMD.

How Many Women Have Osteoporosis

Abstract: Osteoporosis is widely viewed as a major public health concern, but the exact magnitude of the problem is uncertain and likely to depend on how the condition is defined. Noninvasive bone mineral measurements can be used to define a state of heightened fracture risk (osteopenia), or the ultimate clinical manifestation of fracture can be assessed (established osteoporosis). If bone mineral measurements more than 2 standard deviations below the mean of young normal women represent osteopenia, then 45% of white women aged 50 years and over have the condition at one or more sites in the hip, spine, or forearm on the basis of population-based data from Rochester, Minnesota. A smaller proportion is affected at each specific skeletal site: 32% have bone mineral values this low in the lumbar spine, 29% in either of two regions in the proximal femur, and 26% in the midradius. Although this overall estimate is substantial, some other serious chronic diseases are almost as common. More importantly, low bone mass is associated with adverse health outcomes, especially fractures. The lifetime risk of any fracture of the hip, spine, or distal forearm is almost 40% in white women and 13% in white men from age 50 years onward. If the enormous costs associated with these fractures are to be reduced, increased attention must be given to the design and implementation of control programs directed at this major health problem.

Effects of Sex and Age on Bone Microstructure at the Ultradistal Radius: A Population-Based Noninvasive In Vivo Assessment

Abstract: In a population-based cross-sectional study, we examined effects of sex and age on bone microstructure at the wrist using high-resolution 3-D pQCT. Compared with women, men had thicker trabeculae in young adulthood and had less microstructural damage with aging. These findings may contribute to the virtual immunity of men to age-related increases in wrist fractures. Introduction Although changes in bone microstructure contribute to fracture risk independently of BMD, it has not heretofore been possible to assess this noninvasively in population-based studies.

Use of oral corticosteroids and risk of fractures (reprinted from JBMR, vol. 15, pg. 993-1000, yr. 2000)

Abstract: Treatment with oral corticosteroids is known to decrease bone density but there are few data on the attendant risk of fracture and on the reversibility of this risk after cessation of therapy. A retrospective cohort study was conducted in a general medical practice setting in the United Kingdom (using data from the General Practice Research Database [GPRD]). For each oral corticosteroid user aged 18 years or older, a control patient was selected randomly, who was matched by age, sex, and medical practice. The study comprised 244,235 oral corticosteroid users and 244,235 controls. The average age was 57.1 years in the oral corticosteroid cohort and 56.9 years in the control cohort. In both cohorts 58.6% were female. The most frequent indication for treatment was respiratory disease (40%). The relative rate of nonvertebral fracture during oral corticosteroid treatment was 1.33 (95% confidence interval [CI], 1.29–1.38), that of hip fracture 1.61 (1.47–1.76), that of forearm fracture 1.09 (1.01–1.17), and that of vertebral fracture 2.60 (2.31–2.92). A dose dependence of fracture risk was observed. With a standardized daily dose of less than 2.5 mg prednisolone, hip fracture risk was 0.99 (0.82–1.20) relative to control, rising to 1.77 (1.55–2.02) at daily doses of 2.5–7.5 mg, and 2.27 (1.94–2.66) at doses of 7.5 mg or greater. For vertebral fracture, the relative rates were 1.55 (1.20–2.01), 2.59 (2.16–3.10), and 5.18 (4.25–6.31), respectively. All fracture risks declined toward baseline rapidly after cessation of oral corticosteroid treatment. These results quantify the increased fracture risk during oral corticosteroid therapy, with greater effects on the hip and spine than forearm. They also suggest a rapid offset of this increased fracture risk on cessation of therapy, which has implications for the use of preventative agents against bone loss in patients at highest risk.

Relationship between osteoporosis and cardiovascular disease in postmenopausal women.

Abstract: In the placebo group of the MORE study, including 2576 postmenopausal women (mean age, 66.5 years), the authors describe a strong linear association between the severity grade of osteoporosis (from low BMD to presence of severe vertebral fractures) and the future risk of cardiovascular events. Accordingly, treatment of postmenopausal osteoporosis should include consideration of measures to prevent adverse cardiovascular outcomes. Introduction: Observations indicate an inverse association between BMD and the severity of peripheral atherosclerosis in postmenopausal women. The predictive value of osteoporosis and its different severity stages for the risk of acute cardiovascular events remains unknown. Materials and Methods: Participants were 2576 women (mean age, 66.5 years) assigned to placebo and followed for 4 years in an osteoporosis treatment trial. Those with at least one vertebral fracture or total hip BMD T score ≤ −2.5 at baseline were defined as having osteoporosis, whereas those without vertebral fracture and total hip BMD T score between −2.5 and −1 were defined as having low bone mass. The primary outcome for these posthoc analyses was the incidence of adjudicated fatal or nonfatal cardiovascular events. Results: After adjustment for potential confounders, women with osteoporosis had a 3.9-fold (95% CI, 2.0–7.7; p < 0.001) increased risk for cardiovascular events compared with women with low bone mass. Under the same boundaries, a total hip BMD T score ≤ −2.5 versus a T score between −2.5 and −1 was associated with a 2.1-fold (95% CI, 1.2–3.6; p < 0.01) increase in risk, whereas presence of at least one vertebral fracture versus no vertebral fracture at baseline was associated with a 3.0-fold (95% CI, 1.8–5.1; p < 0.001) increase in risk. The risk of cardiovascular events increased incrementally with the number and increasing severity of baseline vertebral fractures (both p < 0.001). Conclusions: Postmenopausal women with osteoporosis are at an increased risk for cardiovascular events that is proportional to the severity of osteoporosis at the time of the diagnosis. Treatment of postmenopausal osteoporosis should include consideration of measures to prevent cardiovascular outcomes.

A New Population of Human Adult Dental Pulp Stem Cells: A Useful Source of Living Autologous Fibrous Bone Tissue (LAB)

Abstract: Stem cells, derived from human adult dental pulp of healthy subjects 30-45 years of age, were cultured, and cells were selected using a FACSorter. A new c-kit+/CD34+/CD45− cell population of stromal bone producing cells (SBP/DPSCs) was selected, expanded, and cultured. These SBP/DPSCs are highly clonogenic and, in culture, differentiate into osteoblast precursors (CD44+/RUNX-2+), still capable of self-renewing, and then in osteoblasts, producing, in vitro, a living autologous fibrous bone (LAB) tissue, which is markedly positive for several bone antibodies. This tissue constitute an ideal source of osteoblasts and mineralized tissue for bone regeneration. In fact, after in vivo transplantation into immunocompromised rats, LAB formed lamellar bone-containing osteocytes. Introduction: Recently it has been reported that human dental pulp stem cells (DPSCs) are detectable, in humans, only up to the age of 30 years and that they are able to produce in vitro only sporadic calcified nodules and to form, after transplantation in vivo, a mineralized tissue. Materials and Methods: Stem cells, derived from human adult dental pulp of healthy subjects 30-45 years of age, were cultured, and cells were selected using a FACSorter. Light microscope, histochemistry, immunofluorescence, and RT-PCR analyses were performed to study both stem and differentiating cells. Results and Conclusions: A new c-kit+/CD34+/CD45− cell population of stromal bone producing cells (SBP/DPSCs) has been selected by FACSorting, expanded, and cultured. These SBP/DPSCs are highly clonogenic and, in culture, differentiate into osteoblast precursors (CD44+/RUNX-2+), still capable of self-renewing, and in osteoblasts, producing, in vitro, a living autologous fibrous bone (LAB) tissue. This new-formed tissue is markedly positive for several antibodies for bone, including osteonectin, bone sialoprotein, osteocalcin, fibronectin, collagen III, and bone alkaline phosphatase (BALP). Cells producing LAB can be stored at −80°C for a long period of time and are an extraordinary source of osteoblasts and mineralized fibrous bone tissue. In this study, we also showed that, in aged humans, stem cells can be detected from their pulps. The produced LAB is a fibrous bone tissue resembling the human bone during mineralization, with an external layer formed by osteoblasts markedly positive for osteocalcin. This newly formed tissue constitute an ideal source of osteoblasts and mineralized tissue for bone regeneration. In fact, after in vivo transplantation into immunocompromised rats, LAB formed lamellar bone containing osteocytes.

An Uncoupling Agent Containing Strontium Prevents Bone Loss by Depressing Bone Resorption and Maintaining Bone Formation in Estrogen-Deficient Rats

Abstract: Trabecular bone loss in estrogen deficiency is associated with enhanced bone resorption with a smaller increase in bone formation. We previously reported that low doses of strontium can increase trabecular bone volume in rodents by affecting bone resorption and formation. In this study we determined the effect of a new divalent strontium salt (S12911) on bone loss induced by E2 deficiency. Sprague-Dawley female rats (230 g, n = 15-25 per group) were sham operated or ovariectomized (OVX) and treated with 17 beta-estradiol (E2, 10 micrograms/kg/day, sc) or S12911 by gavage at the dose of 77, 154, or 308 mg/kg/day or the vehicle. Treatment for 60 days with S12911 resulted in a dose-dependent increase in plasma, urine, and bone strontium concentrations without any deleterious effect on total or skeletal growth. OVX rats were osteopenic compared to sham rats as shown by decreased femoral dry bone weight and mineral content measured on bone ash and by DXA. Treatment of OVX rats with S12911 prevented bone loss as bone ash and bone mineral content were restored to the values in sham rats. Trabecular bone volume measured by histomorphometry on the tibial metaphysis was decreased by 46% in OVX rats and was corrected by E2. Treatment of OVX rats with S12911 increased the trabecular bone volume by 30-36%. Histomorphometric indices of bone resorption (osteoclast surface and number) were increased in OVX rats and were reduced by S12911 to the levels in sham rats.(ABSTRACT TRUNCATED AT 250 WORDS)

VEGF improves, whereas sFlt1 inhibits, BMP2-induced bone formation and bone healing through modulation of angiogenesis.

Abstract: We studied the interaction between VEGF and BMP2 during bone formation and bone healing. Results indicate that VEGF antagonist inhibited BMP2-elicited bone formation, whereas the delivery of exogenous VEGF enhanced BMP2-induced bone formation and bone healing through modulation of angiogenesis. Introduction: Angiogenesis is closely associated with bone formation during normal bone development and is important for the bone formation elicited by BMP4. However, it remains unknown whether vascular endothelial growth factor (VEGF) also interacts with other BMPs, especially BMP2, in bone formation and bone healing. Materials and Methods: For this study, mouse muscle-derived stem cells were transduced to express BMP2, VEGF, or VEGF antagonist (sFlt1). We studied the angiogenic process during endochondral bone formation elicited by BMP2, a prototypical osteogenic BMP. Using radiographic and histologic analyses, we also evaluated the interaction between VEGF and BMP2 during bone formation and bone healing. Results: Our results indicate that BMP2-elicited bone formation comprises two phases of angiogenesis, with an early phase occurring before the appearance of hypertrophic cartilage, followed by a late phase coupled with the appearance of hypertrophic cartilage. Our finding that the administration of sFlt1, a specific antagonist of VEGF, significantly inhibited BMP2-induced bone formation and the associated angiogenesis indicates that endogenous VEGF activity is important for bone formation. Furthermore, we found that the delivery of exogenous VEGF enhanced BMP2-induced bone formation and bone healing by improving angiogenesis, which in turn led to accelerated cartilage resorption and enhanced mineralized bone formation. Our findings also indicate that the ratio between VEGF and BMP2 influences their synergistic interaction, with a higher proportion of VEGF leading to decreased synergism. Our study also revealed unique VEGF-BMP2 interactions that differ from the VEGF-BMP4 interactions that we have described previously. Conclusions: This study, along with previously published work, shows that VEGF interacts synergistically with both BMP4 and BMP2 but elicits substantially different effects with these two BMPs.

Incidence of Primary Hyperparathyroidism in Rochester, Minnesota, 1993–2001: An Update on the Changing Epidemiology of the Disease†

Abstract: We updated the incidence of primary hyperparathyroidism in Rochester, Minnesota. The lower rates previously noted persisted, whereas parathyroidectomies at our institution remained high. These data suggest an etiologic factor may be responsible for the peak incidence in the 1970s. Introduction: Automated serum calcium measurements were associated with a dramatic rise in primary hyperparathyroidism in the early 1970s, but a progressive decline in the incidence thereafter was unexpected and suggested a fundamental change in the epidemiology of the disease. Our objective was to evaluate trends in the incidence of primary hyperparathyroidism since 1992. Materials and Methods: In this population-based descriptive study, Rochester, MN, residents who met defined diagnostic criteria for primary hyperparathyroidism from January 1993 through December 2001 were identified through the medical record linkage system of the Rochester Epidemiology Project and the Mayo Clinic Laboratory Information System. Changes in incidence were evaluated by Poisson regression. Results: Altogether, 136 Rochester residents (94 women and 42 men) were newly identified with primary hyperparathyroidism in 1993–2001. Their mean age was 56 years, and 93% had definite disease. The overall age- and sex-adjusted (to 2000 U.S. whites) rate during this period was 21.6 per 100,000 person-years, which was less than the annual rate of 29.1 per 100,000 observed in 1983–1992 and 82.5 per 100,000 in July 1974–1982. Although community incidence declined, the number of parathyroidectomies performed at our institution increased during the same period. Serum calcium was deleted from the automated chemistry panel in June 1996, but most subjects remained asymptomatic at diagnosis (95%) with mild hypercalcemia. The majority of subjects were observed without parathyroid surgery (75%), and there was minimal impact on patient management from the 1990 NIH consensus conference on asymptomatic primary hyperparathyroidism. Conclusions: The lower incidence of primary hyperparathyroidism noted through 1992 has persisted in our community through 2001, whereas parathyroidectomies at our institution remained high. These data suggest that some underlying etiologic factor, in addition to the introduction of automated serum calcium testing, may have been responsible for the peak incidence in the 1970s.

Identification of Osteopenic Women at High Risk of Fracture: The OFELY Study

Abstract: About one-half of women with incident fractures have BMD above the WHO diagnostic threshold of osteoporosis. In the OFELY study, low BMD, increased markers of bone turnover, and prior fracture could be used to identify, within osteopenic women, those at high risk of fracture. Introduction: Recent data suggest that about one-half of women with incident fractures have BMD above the World Health Organization (WHO) diagnostic threshold of osteoporosis (T score ≤ −2.5). We aimed to identify, within osteopenic women, those at high risk of fracture. Materials and Methods: In the 671 postmenopausal women (mean age: 62 years) belonging to the Os des Femmes de Lyon (OFELY) population-based prospective cohort, we measured at baseline BMD by DXA at the spine and total hip, bone turnover markers (BTM) and clinical risk factors for osteoporosis. All fragility vertebral or nonvertebral fractures, confirmed by radiographs, were assessed during a median follow-up of 9.1 years (IQ: 2.3). Results: 158 incident fractures were recorded in 116 women: 8% in normal, 48% in osteopenic, and 44% in osteoporotic women. Among osteopenic women, low BMD (−2.5 < T score ≤ −2.0) was associated with an increased fracture risk with an age-adjusted hazard ratio (HR) of 2.5 (1.3-4.6). In addition, age, prior fracture, and high BTM—but not other risk factors—were independently associated with an increased fracture risk with an age-adjusted HR of 2.2 (1.2-4.3) for prior fractures and 2.2 (1.4-3.8) for bone alkaline phosphatase (BALP) in the highest quartile. In the whole group of osteopenic women, a large majority of incident fractures occurred in those with a low BMD, prior fractures, or BALP in the highest quartile, with an age-adjusted HR of 5.3 (2.3-11.8). The 10-year probability of fracture in osteopenic women was 26% if at least one predictor was present, contrasting with 6% in those without any of the three risk factors. Conclusions: In postmenopausal women with osteopenia, low BMD, increased BTM, and prior fracture are associated with an increased risk of fracture in the subsequent 10 years. Their assessment may play an important role in identifying women at high risk of fracture who could not be adequately detected by BMD measurement alone and who may benefit from a therapeutic intervention.

The bisphosphonate alendronate (MK-217) inhibits bone loss due to ovariectomy in rats.

Abstract: Estrogen deficiency in mammals is known to increase bone turnover and result in reduced bone mass. The bisphosphonate, 4-amino-1-hydroxybutylidene-1,1-bisphophonic acid disodium salt, alendronate (MK-217), is a potent inhibitor of bone resorption and was evaluated in this study for its ability to inhibit bone loss following ovariectomy in rats. Alendronate was administered sc in doses of 0.0, 0.056, 0.28, 1.40, and 7.0 mg P/kg/month, divided into two, four, or eight monthly subcutaneous injections for each dose, to female Sprague-Dawley rats (250-280 g) that underwent bilateral ovariectomy. Rats were sacrificed 12 weeks postovariectomy, the femora ashed, and the tibiae prepared for static and dynamic histomorphometric analyses. Femoral bone mass in vehicle-treated rats was reduced by 12% 12 weeks after ovariectomy compared to the nonovariectomized control group. In MK-217-treated rats femoral bone mass was significantly increased in a dose-dependent manner compared to either ovariectomized or nonovariectomized controls. Histomorphometric analysis showed significant increases in tibial trabecular bone volume with no decrease in osteoclast number. Doses delivered twice per month or eight times per month were equally effective in achieving the peak bone volume 12 weeks after ovariectomy. In conclusion, alendronate (MK-217) was effective in inhibiting bone loss due to estrogen deficiency in rats, and the magnitude of its effect was related primarily to the total amount of compound administered rather than the frequency of its administration.

Effect of IGF-I in the chondrogenesis of bone marrow mesenchymal stem cells in the presence or absence of TGF-β signaling

Abstract: A novel role for IGF-I in MSC chondrogenesis was determined. IGF-I effects were evaluated in the presence or absence of TGF-β signaling by conditionally inactivating the TGF-β type II receptor. We found that IGF-I had potent chondroinductive actions on MSCs. IGF-I effects were independent from and additive to TGF-β. Introduction: Mesenchymal stem cells (MSCs) can be isolated from adult bone marrow (BM), expanded, and differentiated into several cell types, including chondrocytes. The role of IGF-I in the chondrogenic potential of MSCs is poorly understood. TGF-β induces MSC chondrogenic differentiation, although its actions are not well defined. The aim of our study was to define the biological role of IGF-I on proliferation, chondrogenic condensation, apoptosis, and differentiation of MSCs into chondrocytes, alone or in combination with TGF-β and in the presence or absence of TGF-β signaling. Materials and Methods: Mononuclear adherent stem cells were isolated from mouse BM. Chondrogenic differentiation was induced by culturing high-density MSC pellets in serum- and insulin-free defined medium up to 7 days, with or without IGF-I and/or TGF-β. We measured thymidine incorporation and stained 2-day-old pellets with TUNEL, cleaved caspase-3, peanut-agglutinin, and N-cadherin. Seven-day-old pellets were measured in size, stained for proteoglycan synthesis, and analyzed for the expression of collagen II and Sox-9 by quantitative real time PCR. We obtained MSCs from mice in which green fluorescent protein (GFP) was under the Collagen2 promoter and determined GFP expression by confocal microscopy. We conditionally inactivated the TGF-β type II receptor (TβRII) in MSCs using a cre-lox system, generating TβRII knockout MSCs (RIIKO-MSCs). Results and Conclusions: IGF-I modulated MSC chondrogenesis by stimulating proliferation, regulating cell apoptosis, and inducing expression of chondrocyte markers. IGF-I chondroinductive actions were equally potent to TGF-β1, and the two growth factors had additive effects. Using RIIKO-MSCs, we showed that IGF-I chondrogenic actions are independent from the TGF-β signaling. We found that the extracellular signal-related kinase 1/2 mitogen-activated protein kinase (Erk1/2 MAPK) pathway mediated the TGF-β1 mitogenic response and in part the IGF-I proliferative action. Our data, by showing the role of IGF-I and TGF-β1 in the critical steps of MSC chondrogenesis, provide critical information to optimize the therapeutic use of MSCs in cartilage disorders.

Monthly oral ibandronate therapy in postmenopausal osteoporosis: 1-year results from the MOBILE study.

Abstract: Once-monthly (50/50, 100, and 150 mg) and daily (2.5 mg; 3-year vertebral fracture risk reduction: 52%) oral ibandronate regimens were compared in 1609 women with postmenopausal osteoporosis. At least equivalent efficacy and similar safety and tolerability were shown after 1 year. Introduction: Suboptimal adherence to daily and weekly oral bisphosphonates can potentially compromise therapeutic outcomes in postmenopausal osteoporosis. Although yet to be prospectively shown in osteoporosis, evidence from randomized clinical trials in several other chronic conditions shows that reducing dosing frequency enhances therapeutic adherence. Ibandronate is a new and potent bisphosphonate with antifracture efficacy proven for daily administration and also intermittent administration with a dose-free interval of >2 months. This report presents comparative data on the efficacy and safety of monthly and daily oral ibandronate regimens. Materials and Methods: MOBILE is a 2-year, randomized, double-blind, phase III, noninferiority trial. A total of 1609 women with postmenopausal osteoporosis were assigned to one of four oral ibandronate regimens: 2.5 mg daily, 50 mg/50 mg monthly (single doses, consecutive days), 100 mg monthly, or 150 mg monthly. Results: After 1 year, lumbar spine BMD increased by 3.9%, 4.3%, 4.1%, and 4.9% in the 2.5, 50 /50, 100, and 150 mg arms, respectively. All monthly regimens were proven noninferior, and the 150 mg regimen superior, to the daily regimen. All monthly regimens produced similar hip BMD gains, which were larger than those with the daily regimen. All regimens similarly decreased serum levels of C-telopeptide, a biochemical marker of bone resorption. Compared with the daily regimen, a significantly larger proportion of women receiving the 100 and 150 mg monthly regimens achieved predefined threshold levels for percent change from baseline in lumbar spine (6%) or total hip BMD (3%). All regimens were similarly well tolerated. Conclusions: Monthly ibandronate is at least as effective and well tolerated as the currently approved daily ibandronate regimen in postmenopausal osteoporosis.

Glucocorticoid-Treated Mice Have Localized Changes in Trabecular Bone Material Properties and Osteocyte Lacunar Size That Are Not Observed in Placebo-Treated or Estrogen-Deficient Mice†

Abstract: This study compares changes in bone microstructure in 6-month-old male GC-treated and female ovariectomized mice to their respective controls. In addition to a reduction in trabecular bone volume, GC treatment reduced bone mineral and elastic modulus of bone adjacent to osteocytes that was not observed in control mice nor estrogen-deficient mice. These microstructural changes in combination with the macro-structural changes could amplify the bone fragility in this metabolic bone disease. Introduction Patients with glucocorticoid (GC)-induced secondary osteoporosis tend to fracture at higher bone mineral densities than patients with postmenopausal osteoporosis. This suggests that GCs may alter bone material properties in addition to BMD and bone macrostructure.

Periosteal Progenitor Cell Fate in Segmental Cortical Bone Graft Transplantations: Implications for Functional Tissue Engineering

Abstract: A murine segmental femoral bone graft model was used to show the essential role of donor periosteal progenitor cells in bone graft healing. Transplantation of live bone graft harvested from Rosa 26A mice showed that ∼70% of osteogenesis on the graft was attributed to the expansion and differentiation of donor periosteal progenitor cells. Furthermore, engraftment of BMP-2-producing bone marrow stromal cells on nonvital allografts showed marked increases in cortical graft incorporation and neovascularization, suggesting that gene-enhanced, tissue engineered functional periosteum may improve allograft incorporation and repair. Introduction: The loss of cellular activity in a structural bone allograft markedly reduces its healing potential compared with a live autograft. To further understand the cellular mechanisms for structural bone graft healing and repair and to devise a therapeutic strategy aimed at enhancing the performance of allograft, we established a segmental femoral structural bone graft model in mice that permits qualitative and quantitative analyses of graft healing and neovascularization. Materials and Methods: Using this segmental femoral bone graft model, we transplanted live isografts harvested from Rosa 26A mice that constitutively express β-galactosidase into their wildtype control mice. In an attempt to emulate the osteogenic and angiogenic properties of periosteum, we applied a cell-based, adenovirus-mediated gene therapy approach to engraft BMP-2-producing bone marrow stromal cells onto devitalized allografts. Results: X-gal staining for donor cells allowed monitoring the progression of periosteal progenitor cell fate and showed that 70% of osteogenesis was attributed to cellular proliferation and differentiation of donor progenitor cells on the surface of the live bone graft. Quantitative μCT analyses showed a 3-fold increase in new bone callus formation and a 6.8-fold increase in neovascularization for BMP-2/stromal cell-treated allograft compared with control acellular allografts. Histologic analyses showed the key features of autograft healing in the BMP-2/stromal cell-treated allografts, including the formation of a mineralized bone callus completely bridging the segmental defects, abundant neovascularization, and extensive resorption of bone graft. Conclusions: The marked improvement of healing in these cellularized allografts suggests a clinical strategy for engineering a functional periosteum to improve the osteogenic and angiogenic properties of processed allografts.

Vascular endothelial growth factor gene-activated matrix (VEGF165-GAM) enhances osteogenesis and angiogenesis in large segmental bone defects.

Abstract: Healing of fractures is dependent on vascularization of bone, which is in turn promoted by VEGF. It was shown that 0.1 and 1 mg of pVEGF165-GAM led to a significant increase in vascularization and bone regeneration in defects that would otherwise have led to atrophic nonunions. Introduction: One reason for lack of bone healing in nonunions is the absence of vascularization. In skeletogenesis, which is tightly linked to angiogenesis, vascular endothelial growth factor (VEGF) promotes the vascularization of the growth plate and transformation of cartilage to bone. We postulate that a gene-activated matrix (GAM), created with a plasmid coding for human VEGF165, coated on a collagen sponge could efficiently accelerate bone healing in large segmental defects. Materials and Methods: Sixty New Zealand white rabbits received a 15-mm critical size defect on one radius, which was filled with either 0.1 or 1 mg plasmid-DNA as GAM. Radiographs were obtained every 3 weeks. After 6 or 12 weeks, animals were killed. New bone was measured by μCT scans. Vascularity was measured using anti-CD31 staining of endothelial cells in 18 regions of interest per implant. Results: Scaffold and control plasmid showed no defect healing, whereas most of the animals in the VEGF groups showed partial or total bone regeneration. Significantly more bone was found in the VEGF groups, with no significant differences between the 0.1- and 1-mg groups. Immunohistochemical staining of endothelial cells revealed that the VEGF groups showed two to three times the number of vessels and a significantly larger endothelial area after 6 weeks. Twelve weeks after surgery, the amount of vascularization decreased, whereas more new bone was detectable. Conclusions: The rabbit critical size defect was appropriate in size to produce atrophic nonunions. We showed that angiogenesis and osteogenesis can be promoted by a VEGF165-GAM that is an appropriate tool to induce bone healing in atrophic nonunions.

Early Changes in Biochemical Markers of Bone Formation Predict BMD Response to Teriparatide in Postmenopausal Women With Osteoporosis

Abstract: UNLABELLED: The relationship between early changes in biochemical markers of bone turnover and the subsequent BMD response to daily teriparatide therapy in women with postmenopausal osteoporosis was studied. Changes in five biochemical markers, obtained from a subset of women enrolled in the Fracture Prevention Trial, were examined. Early increases in the PICP and the PINP were the best predictors of BMD response to teriparatide in this analysis. INTRODUCTION: Early reductions in biochemical markers of bone turnover with antiresorptive therapy negatively correlate with subsequent increases in BMD. We undertook this analysis to determine if early changes in biochemical markers with teriparatide therapy predict subsequent increases in BMD. MATERIALS AND METHODS: In the Fracture Prevention Trial, 1637 postmenopausal women with osteoporosis were randomized to receive daily, self-administered, subcutaneous injections of placebo, teriparatide 20 microg/day, or teriparatide 40 microg/day. Serum concentrations of two bone formation markers (bone-specific alkaline phosphatase [bone ALP] and the carboxy-terminal extension peptide of procollagen type 1 [PICP]) and urinary concentrations of two bone resorption markers (free deoxypyridinoline [DPD] and N-terminal telopeptide [NTX]) were assessed in a trial population subset (n = 520) at baseline and at 1, 3, 6, and 12 months. We also assessed serum concentrations of another bone formation marker, the amino-terminal extension peptide of procollagen type 1 (PINP), in a subset of 771 women at baseline and 3 months. Lumbar spine (LS) BMD was measured by DXA at baseline and 18 months. Femoral neck BMD was measured at baseline and 12 months. RESULTS AND CONCLUSION: Baseline bone turnover status correlated positively and significantly with BMD response. The highest correlations occurred for the LS BMD response to teriparatide 20 microg/day. Among all studied biochemical markers, increases in PICP at 1 month and PINP at 3 months correlated best with increases in LS BMD at 18 months (0.65 and 0.61, respectively; p < 0.05). The relationships between these two biochemical markers and the LS BMD response were stronger than the corresponding relationships for the femoral neck BMD response. Using receiver operator curve analysis, we determined that the increases in PICP at 1 month and PINP at 3 months were the most sensitive and accurate predictors of the LS BMD response.

Safety and efficacy of risedronate in patients with age-related reduced renal function as estimated by the Cockcroft and Gault method: a pooled analysis of nine clinical trials

Abstract: The incidences of osteoporosis and renal insufficiency increase with age. We studied the influence of renal function on the safety and efficacy of risedronate 5 mg daily in osteoporotic women. Risedronate was safe and effective in osteoporotic women with mild, moderate, or severe age-related renal impairment. Introduction: The incidences of both osteoporosis and renal insufficiency increase with age; thus, the effect of renal impairment on the safety and efficacy of osteoporosis treatments is a clinical concern. Risedronate is a pyridinyl bisphosphonate well established as safe and effective in the treatment and prevention of osteoporosis. Currently, there is little available information about the effect of bisphosphonate treatment in patients with renal insufficiency. This retrospective analysis was conducted to study the influence of renal function on the safety and efficacy of risedronate in a population of osteoporotic women. Materials and Methods: Combined data from nine randomized, double-blind, placebo-controlled phase III risedronate trials were analyzed. The patients in these studies had no markedly abnormal laboratory parameters that were considered clinically significant and no evidence of significant disease. This analysis included patients who received placebo (n = 4500) or risedronate 5 mg (n = 4496) for up to 3 years (average duration of exposure, 2 years) and who had renal impairment (creatinine clearance [CrCl] < 80 ml/min). CrCl was estimated by the Cockcroft and Gault method, based on age, weight, and serum creatinine. Patients were categorized as having mild (CrCl ≥50 to <80 ml/min), moderate (CrCl ≥30 to <50 ml/min), or severe (CrCl < 30 ml/min) renal impairment. Results: Of the patients studied, renal impairment at baseline was mild in 48% (mean [range] serum creatinine, 0.9 [0.4–1.6] mg/dl), moderate in 45% (1.1 [0.6–1.9] mg/dl), and severe in 7% (1.3 [0.7–2.7] mg/dl). In both the placebo and risedronate treatment groups, the patients with the most severe renal impairment were older and had more severe osteoporosis. The incidences of overall adverse events and of renal function-related adverse events were similar in the placebo and risedronate 5 mg groups regardless of renal function. Furthermore, evaluation of changes from baseline in serum creatinine revealed no difference in renal function between the placebo and risedronate 5 mg groups in any of the renal impairment subgroups at any time-point. In all three subgroups, risedronate effectively preserved BMD and reduced the incidence of vertebral fractures. Conclusions: These findings show that risedronate is safe and effective in osteoporotic women with age-related mild, moderate, or severe renal impairment.

What proportion of incident radiographic vertebral deformities is clinically diagnosed and vice versa

Abstract: We prospectively examined, in a large cohort of older women, the proportion of incident radiographic vertebral deformities diagnosed as incident clinical vertebral fractures in the same women at the same vertebral level. The proportion of deformities clinically diagnosed ranged from <15% for milder de- formities to nearly 30% for more severe deformities. Introduction: The relationship between radiographic and clinical vertebral fractures is incompletely under- stood. No previous study has prospectively compared the agreement between incident radiographic vertebral deformities and incident community-recognized, radiographically confirmed vertebral fractures in the same women at the same vertebral level(s). Materials and Methods: This analysis of data from the Fracture Intervention Trial included all participants who completed both baseline and at least one scheduled follow-up lateral spinal radiograph (n 6084). Incident vertebral deformities were defined at a given vertebral level as a reduction between baseline and closeout radiographs of 20% and 4 mm in any vertebral height and subdivided into two severity categories. Incident clinical vertebral fractures were those reported to clinical centers by participants and confirmed by the study radiologist, who compared the community spinal radiograph with the participant's baseline study radiograph using semiquantitative methods. Results: A total of 446 incident radiographic vertebral deformities were identified in 330 women, whereas 121 women experienced one or more confirmed incident clinical vertebral fracture. Of incident radiograpic ver- tebral deformities, 22.6% were also clinically diagnosed as incident vertebral fractures, with clinical diagnoses made for 28.4% of the deformities that exceeded 30% and 4 mm height loss (severe deformity) compared with 14.3% for deformities that involved 20% and 4 mm but <30% height loss (milder deformity). Of incident clinical vertebral fractures, 72.7% were morphometrically identified as incident deformities, most of them as severe deformities. More than 20% of incident clinical fractures were not identified as incident deformities by even the most liberal morphometric criterion used in this study. Conclusions: Approximately one-fourth of incident radiographic vertebral deformities were clinically diag- nosed as new vertebral fractures, although the proportion clinically diagnosed was increased for more severe deformities. Whereas most incident clinical vertebral fractures were identified as severe morphometric de- formities, approximately one-fourth did not meet even the most liberal study criterion for morphometric deformity. Further study of factors that may explain the discordance between incident vertebral deformities and incident clinical vertebral fractures is important. J Bone Miner Res 2005;20:1216-1222. Published online on March 21, 2005; doi: 10.1359/JBMR.050314

Bone and Body Composition of Children and Adolescents With Repeated Forearm Fractures

Abstract: DXA measurements in 90 children and adolescents with repeated forearm fractures showed reduced ultradistal radius BMC and BMD values and elevated adiposity, suggesting site-specific bone weakness and high body weight increase fracture risk. Symptoms to cow milk, low calcium intakes, early age of first fracture, and overweight were over-represented in the sample. Introduction: Although many apparently healthy children fracture their forearms repeatedly during growth, no previous studies of their bone health and body composition have been undertaken. Nor has the prevalence of established risk factors for fracture in such a population been assessed. Materials and Methods: Ninety children and adolescents (47 girls and 43 boys) 5–19 years of age, who had experienced at least two fractures of the forearm, were studied. Bone size and mineralization were assessed using DXA at the ultradistal radius, one-third radius, neck of femur, hip trochanter, lumbar spine, and total body. Total body lean mass and fat mass were also determined. The prevalence of six risk factors for fracture were also examined, and their influence on ultradistal BMC Z scores was assessed. Results: Participants experienced 295 fractures (74.9% forearm). Children with an early age of first fracture had higher rates of fracture per l00 years of exposure than those fracturing later. Four risk factors for fracture were over-represented in observed versus expected percentages: early age of first fracture (27.7% versus 11.3%), adverse symptoms to cow milk (22.2% versus 6.7%), low dietary calcium intake (20% versus 4.5%), and overweight (33.3% versus 15.5%). However, physical activity levels were similar to the reference population. Z scores for BMC and BMD were reduced, particularly at the ultradistal radius, whereas Z scores for weight, body mass index, fat mass, and body fat percentage were increased. Mean (SD) BMC Z scores were lowest at the ultradistal radius, −0.66 (1.22), where symptoms to milk were associated with reduced values (p < 0.009) and overweight with increased values (p < 0.003). Conclusions: Our results suggest site-specific weakness and high body weight contribute to fracture risk in children and adolescents who fracture their forearms repeatedly. These findings are consonant with work showing adult Colles fractures increase as ultradistal radius BMD falls and with evidence that overweight children and adolescents are fracture prone.

Cortical and trabecular load sharing in the human vertebral body.

Abstract: The biomechanical role of the vertebral cortical shell remains poorly understood Using high-resolution finite element modeling of a cohort of elderly vertebrae, we found that the biomechanical role of the shell can be substantial and that the load sharing between the cortical and trabecular bone is complex As a result, a more integrative measure of the trabecular and cortical bone should improve noninvasive assessment of fracture risk and treatments Introduction: A fundamental but poorly understood issue in the assessment of both osteoporotic vertebral fracture risk and effects of treatment is the role of the trabecular bone and cortical shell in the load-carrying capacity of the vertebral body Materials and Methods: High-resolution μCT-based finite element models were developed for 13 elderly human vertebrae (age range: 54–87 years; 746 ± 94 years), and parameter studies—with and without endplates—were performed to determine the role of the shell versus trabecular bone and the effect of model assumptions Results: Across vertebrae, whereas the average thickness of the cortical shell was only 038 ± 006 mm, the shell mass fraction (shell mass/total bone mass)—not including the endplates—ranged from 021 to 039 The maximum load fraction taken by the shell varied from 038 to 054 across vertebrae and occurred at the narrowest section The maximum load fraction taken by the trabecular bone varied from 076 to 089 across vertebrae and occurred near the endplates Neither the maximum shell load fraction nor the maximum trabecular load fraction depended on any of the densitometric or morphologic properties of the vertebra, indicating the complex nature of the load sharing mechanism The variation of the shell load-carrying capacity across vertebrae was significantly altered by the removal of endplates, although these models captured the overall trend within a vertebra Conclusions: The biomechanical role of the thin cortical shell in the vertebral body can be substantial, being about 45% at the midtransverse section but as low as 15% close to the endplates As a result of the complexity of load sharing, sampling of only midsection trabecular bone as a strength surrogate misses important biomechanical information A more integrative approach that combines the structural role of both cortical and trabecular bone should improve noninvasive assessment of vertebral bone strength in vivo

Leptin Treatment Induces Loss of Bone Marrow Adipocytes and Increases Bone Formation in Leptin-Deficient ob/ob Mice†

Abstract: Normal mice and leptin-deficient ob/ob mice were treated with leptin to study effects on osteogenesis and adipogenesis in bone marrow. Leptin treatment significantly decreased bone marrow adipocyte size and number in ob/ob mice while increasing bone formation, BMC, and BMD. The results suggest that, in leptin-sensitive animals, the reduction in marrow adipocytes has positive effects on bone formation. Introduction: Adipocytes, osteoblasts, and osteoclasts have leptin receptors, and leptin can also affect bone metabolism indirectly through its receptors in the hypothalamus. We examined the effects of leptin treatment on bone formation, BMD, and marrow adipocyte population in normal mice and leptin-deficient ob/ob mice. Materials and Methods: At the age of 15 weeks, mice were implanted with Alzet osmotic pumps for subcutaneous delivery of treatment solutions (saline, 2.5 μg leptin/day, or 10 μg leptin/day) for 14 days at a delivery rate of 0.25 μl/h. Bone formation was assessed using fluorochrome labels, cell populations were quantified using histomorphometry, and bone densitometry was measured using DXA. We also used a Luminex Beadlyte assay system to quantify cell survival markers in bone marrow samples. Results and Conclusions: Results indicate that both doses of leptin decreased the number of marrow adipocytes in ob/ob mice by >20% (p 30% compared with PBS-treated ob/ob mice. Leptin treatment increased whole body BMC by >30% in the ob/ob mice receiving the highest leptin dose. Leptin treatment provided no increase in bone formation, BMC, or BMD in normal, leptin-replete mice.

Advanced glycation end-products attenuate human mesenchymal stem cells and prevent cognate differentiation into adipose tissue, cartilage, and bone.

Abstract: The impact of AGEs on human MSCs was studied. AGEs inhibited the proliferation of MSCs, induced apoptosis, and prevented cognate differentiation into adipose tissue, cartilage, and bone, suggesting a deleterious effect of AGEs in the pathogenesis of musculoskeletal disorders in aged and diabetic patients. Introduction: Advanced glycation end-products (AGEs) are accumulated on long-lived proteins of various tissues in advanced age and diabetes mellitus and have been implicated in chronic complication, including musculoskeletal disorders. Human mesenchymal stem cells (MSCs) potentially differentiate into mature musculoskeletal tissues during tissue repair, but the pathogenetic role of AGEs on MSCs is unclear. Materials and Methods: AGEs were prepared by incubating BSA with glucose, glyceraldehydes, or glycolaldehyde (designated as AGE-1, AGE-2, or AGE-3, respectively). Proliferation, apoptosis, and reactive oxygen species (ROS) generation were assayed in AGE-treated cells. The expression of the receptor for AGE (RAGE) was examined by immunohistochemistry and Western blotting. Involvement of RAGE-mediated signaling was examined using a neutralizing antiserum against RAGE. Differentiation into adipose tissue, cartilage, and bone were morphologically and biochemically monitored with specific markers for each. Results: AGE-2 and AGE-3, but not control nonglycated BSA and AGE-1, reduced the viable cell number and 5-bromo-2'deoxyuridine (BrdU) incorporation with increased intracellular ROS generation and the percentage of apoptotic cells. MSCs expressed RAGE and its induction was stimulated by AGE-2 and AGE-3. These AGEs inhibited adipogenic differentiation (assayed by oil red O staining, lipoprotein lipase production, and intracellular triglyceride content) and chondrogenic differentiation (assayed by safranin O staining and type II collagen production). On osteogenic differentiation, AGE-2 and AGE-3 increased alkaline phosphatase activity and intracellular calcium content; however, von Kossa staining revealed the loss of mineralization and mature bone nodule formation. The antiserum against RAGE partially prevented AGE-induced cellular events. Conclusion: AGE-2 and AGE-3 may lead to the in vivo loss of MSC mass and the delay of tissue repair by inhibiting the maturation of MSC-derived cells. The AGE-RAGE interaction may be involved in the deleterious effect of AGEs on MSCs.

A novel tetracycline labeling schedule for longitudinal evaluation of the short-term effects of anabolic therapy with a single iliac crest bone biopsy: early actions of teriparatide.

Abstract: We describe a quadruple tetracycline labeling method that allows longitudinal assessment of short-term changes in bone formation in a single biopsy. We show that 1 month of hPTH(1-34) treatment extends the bone-forming surface, increases mineral apposition rate, and initiates modeling-based formation. Introduction: Iliac crest biopsy, with histomorphometric evaluation, provides important information about cellular activity in bone. However, to obtain longitudinal information, repeat biopsies must be performed. In this study, we show the capability to obtain short-term longitudinal information on bone formation in a single biopsy using a novel, quadruple labeling technique. Materials and Methods: Two tetracycline labels were administered using a standard 3 days on, 12 days off, 3 days on format. Four weeks later, the tetracycline labeling was repeated using the same schedule but with a different tetracycline that can be distinguished from the first by its color under fluorescent light. Iliac crest biopsies were performed 1 week later and prepared undecalcified for histomorphometry. Indices of bone formation 1 month apart were measured and calculated using the two sets of labels. We used this method to investigate the early effects of teriparatide [hPTH(1-34)] treatment on bone formation. The results were compared with those from a group of control subjects who were quadruple-labeled, but did not receive hPTH(1-34). Results: Treatment with hPTH(1-34) dramatically stimulated bone formation on cancellous and endocortical surfaces. This was achieved by both an increase in the linear rate of matrix apposition and extension of the bone-forming surface. New bone was deposited on previously quiescent surfaces (i.e., modeling-based formation), but a proportion of this could occur by encroachment from adjacent resorption cavities. Conclusions: A single transiliac crest bone biopsy, after sequential administration of two sets of tetracycline labels is a useful approach to study the short-term effects of anabolic agents on human bone. One month of hPTH(1-34) treatment extends the bone-forming surface, increases mineral apposition rate, and initiates modeling-based formation.

Skeletal effects of raloxifene after 8 years: results from the continuing outcomes relevant to Evista (CORE) study

Abstract: In the CORE breast cancer trial of 4011 women continuing from MORE, the incidence of nonvertebral fractures at 8 years was similar between placebo and raloxifene 60 mg/day. CORE had limitations for assessing fracture risk. In a subset of 386 women, 7 years of raloxifene treatment significantly increased lumbar spine and femoral neck BMD compared from the baseline of MORE. Introduction: The multicenter, double-blind Continuing Outcomes Relevant to Evista (CORE) trial assessed the effects of raloxifene on breast cancer for 4 additional years beyond the 4-year Multiple Outcomes of Raloxifene Evaluation (MORE) osteoporosis treatment trial. Materials and Methods: In CORE, placebo-treated women from MORE continued with placebo (n = 1286), whereas those previously given raloxifene (60 or 120 mg/day) received raloxifene 60 mg/day (n = 2725). As a secondary endpoint, new nonvertebral fractures were analyzed as time-to-first event in 4011 postmenopausal women at 8 years. A substudy assessed lumbar spine and femoral neck BMD at 7 years, with the primary analysis based on 386 women (127 placebo, 259 raloxifene) who did not take other bone-active agents from the fourth year of MORE and who were ≥80% compliant with study medication in CORE. Results: The risk of at least one new nonvertebral fracture was similar in the placebo (22.9%) and raloxifene (22.8%) groups (hazard ratio {HR}, 1.00; Bonferroni-adjusted CI, 0.82, 1.21). The incidence of at least one new nonvertebral fracture at six major sites (clavicle, humerus, wrist, pelvis, hip, lower leg) was 17.5% in both groups. Posthoc Poisson analyses, which account for multiple events, showed no overall effect on nonvertebral fracture risk, and a decreased risk at six major nonvertebral sites in women with prevalent vertebral fractures (HR, 0.78; 95% CI, 0.63, 0.96). At 7 years after MORE randomization, the differences in mean lumbar spine and femoral neck BMD with raloxifene were 1.7% (p = 0.30) and 2.4% (p = 0.045), respectively, from placebo. Compared with MORE baseline, after 7 years, raloxifene treatment significantly increased lumbar spine (4.3% from baseline, 2.2% from placebo) and femoral neck BMD (1.9% from baseline, 3.0% from placebo). BMDs were significantly increased from MORE baseline at all time-points at both sites with raloxifene. Conclusion: Raloxifene therapy had no effect on nonvertebral fracture risk after 8 years, although CORE had limitations for fracture risk assessment. BMD increases were maintained after 7 years of raloxifene.

Ovariectomy-Induced Bone Loss Varies Among Inbred Strains of Mice

Abstract: There is a subset of women who experience particularly rapid bone loss during and after the menopause However, the factors that lead to this enhanced bone loss remain obscure We show that patterns of bone loss after ovariectomy vary among inbred strains of mice, providing evidence that there may be genetic regulation of bone loss induced by estrogen deficiency Introduction: Both low BMD and increased rate of bone loss are risk factors for fracture Bone loss during and after the menopause is influenced by multiple hormonal factors However, specific determinants of the rate of bone loss are poorly understood, although it has been suggested that genetic factors may play a role We tested whether genetic factors may modulate bone loss subsequent to estrogen deficiency by comparing the skeletal response to ovariectomy in inbred strains of mice Materials and Methods: Four-month-old mice from five inbred mouse strains (C3H/HeJ, BALB/cByJ, CAST/EiJ, DBA2/J, and C57BL/6J) underwent ovariectomy (OVX) or sham-OVX surgery (n = 6-9/group) After 1 month, mice were killed, and μCT was used to compare cortical and trabecular bone response to OVX Results: The effect of OVX on trabecular bone varied with mouse strain and skeletal site Vertebral trabecular bone volume (BV/TV) declined after OVX in all strains (−15 to −24%), except for C3H/HeJ In contrast, at the proximal tibia, C3H/HeJ mice had a greater decline in trabecular BV/TV (−39%) than C57BL/6J (−18%), DBA2/J (−23%), and CAST/EiJ mice (−21%) OVX induced declines in cortical bone properties, but in contrast to trabecular bone, the effect of OVX did not vary by mouse strain The extent of trabecular bone loss was greatest in those mice with highest trabecular BV/TV at baseline, whereas cortical bone loss was lowest among those with high cortical bone parameters at baseline Conclusions: We found that the skeletal response to OVX varies in a site- and compartment-specific fashion among inbred mouse strains, providing support for the hypothesis that bone loss during and after the menopause is partly genetically regulated

Use of oral corticosteroids and risk of fractures. June, 2000.

Abstract: Treatment with oral corticosteroids is known to decrease bone density but there are few data on the attendant risk of fracture and on the reversibility of this risk after cessation of therapy. A retrospective cohort study was conducted in a general medical practice setting in the United Kingdom (using data from the General Practice Research Database [GPRD]). For each oral corticosteroid user aged 18 years or older, a control patient was selected randomly, who was matched by age, sex, and medical practice. The study comprised 244,235 oral corticosteroid users and 244,235 controls. The average age was 57.1 years in the oral corticosteroid cohort and 56.9 years in the control cohort. In both cohorts 58.6% were female. The most frequent indication for treatment was respiratory disease (40%). The relative rate of nonvertebral fracture during oral corticosteroid treatment was 1.33 (95% confidence interval [CI], 1.29–1.38), that of hip fracture 1.61 (1.47–1.76), that of forearm fracture 1.09 (1.01–1.17), and that of vertebral fracture 2.60 (2.31–2.92). A dose dependence of fracture risk was observed. With a standardized daily dose of less than 2.5 mg prednisolone, hip fracture risk was 0.99 (0.82–1.20) relative to control, rising to 1.77 (1.55–2.02) at daily doses of 2.5–7.5 mg, and 2.27 (1.94–2.66) at doses of 7.5 mg or greater. For vertebral fracture, the relative rates were 1.55 (1.20–2.01), 2.59 (2.16–3.10), and 5.18 (4.25–6.31), respectively. All fracture risks declined toward baseline rapidly after cessation of oral corticosteroid treatment. These results quantify the increased fracture risk during oral corticosteroid therapy, with greater effects on the hip and spine than forearm. They also suggest a rapid offset of this increased fracture risk on cessation of therapy, which has implications for the use of preventative agents against bone loss in patients at highest risk. (J Bone Miner Res 2000;15:993–1000)

Immune regulation of 25 -hydroxyvitamin -D3 -1α -hydroxylase in human monocytes

Abstract: Monocytes express 1α-hydroxylase, the enzyme responsible for final hydroxylation of vitamin D3, in response to IFNγ and CD14/TLR4 activation. Cross-talk between the JAK-STAT, the NF-κB, and the p38 MAPK pathways is necessary, and direct binding of C/EBPβ to its recognition sites in the promoter of the 1α-hydroxylase gene is a prerequisite. Introduction: The activated form of vitamin D3, 1,25(OH)2D3, known for its action in bone and mineral homeostasis, has important immunomodulatory effects. 1,25(OH)2D3 modulates the immune system through specific nuclear receptors, whereas macrophages produce 1,25(OH)2D3. In monocytes, the expression of 1α-hydroxylase, the enzyme responsible for final hydroxylation of vitamin D3, is regulated by immune stimuli. The aim of this study was to elucidate the intracellular pathways through which interferon (IFN)γ and Toll-like receptor (TLR) modulation regulate expression of 1α-hydroxylase in monocytes/macrophages. Materials and Methods: Monocytes were isolated from peripheral blood mononuclear cells (PBMCs) and stimulated with IFNγ (12.5 U/ml) and/or lipopolysaccharide (LPS; 100 ng/ml) for 48 h. The following inhibitors were used: janus kinase (JAK) inhibitor AG490 (50 μM), NF-κB inhibitor sulfasalazine (0.25 mM), p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 (5 μM). 1α-hydroxylase mRNA expression was monitored by qRT-PCR. Phosphorylation of transcription factors was studied by Western blotting. Transfection of mutated or deletion promoter constructs, cloned in the pGL3-luciferase reporter plasmid, were performed in the RAW264.7 cell line. Cells were stimulated with IFNγ (100 U/ml) and LPS (100 μg/ml), and promoter activity was studied. Binding of signal transducer and activator of transcription (STAT)1α, NF-κB, and C/EBPβ to their respective binding sites in the promoter was analyzed by gel shift assays. Results: 1α-hydroxylase mRNA expression in monocytes is synergistically induced by IFNγ and CD14/TLR4 ligation and paralleled by 1,25(OH)2D3 production. This induction requires the JAK-STAT, NF-κB, and p38 MAPK pathways. Each of them is essential, because blocking individual pathways is sufficient to block 1α-hydroxylase expression (JAK inhibitor, 60% inhibition, p < 0.01; NF-κB inhibitor, 70% inhibition, p < 0.05; p38 MAPK inhibitor, 95% inhibition, p < 0.005). In addition, we show the involvement of the p38 MAPK pathway in phosphorylation of C/EBPβ. Direct binding of C/EBPβ to its recognition sites in the 1α-hydroxylase promoter is necessary to enable its immune-stimulated upregulation. Conclusion: IFNγ and CD14/TLR4 binding regulate expression of 1α-hydroxylase in monocytes in a synergistic way. Combined activation of the JAK-STAT, p38 MAPK, and NF-κB pathways is necessary, with C/EBPβ most probably being the essential transcription factor controlling immune-mediated transcription.

Histone Deacetylase Inhibitors Promote Osteoblast Maturation

Abstract: HDIs are potential therapeutic agents for cancer and neurological diseases because of their abilities to alter gene expression, induce growth arrest or apoptosis of tumors cells, and stimulate differentiation. In this report, we show that several HDIs promote osteoblast maturation in vitro and in calvarial organ cultures. Introduction: Histone deacetylase inhibitors (HDIs) are currently in phase I and II clinical trials as anticancer agents. Some HDIs are also commonly prescribed treatments for epilepsy and bipolar disorders. Although administered systemically, the effects of HDIs on osteoblasts and bone formation have not been extensively examined. In this study, we investigated the effect of histone deacetylase inhibition on osteoblast proliferation and differentiation. Materials and Methods: MC3T3-E1 cells, calvarial-derived primary osteoblasts, and calvarial organ cultures were treated with various commercially available HDIs (trichostatin A [TSA], sodium butyrate [NaB], valproic acid [VPA], or MS-275). The effects of these inhibitors on cell proliferation, viability, cell cycle progression, Runx2 transcriptional activity, alkaline phosphatase production, and matrix mineralization were determined. Expression levels of osteoblast maturation genes, type I collagen, osteopontin, bone sialoprotein, and osteocalcin in response to TSA were measured by quantitative PCR. Results: Concentrations of HDIs that caused hyperacetylation of histone H3 induced transient increases in osteoblast proliferation and viability but did not alter cell cycle profiles. These concentrations of HDIs also increased the transcriptional activity of Runx2. TSA accelerated alkaline phosphatase production in MC3T3-E1 cells and calvarial organ cultures. In addition, TSA accelerated matrix mineralization and the expression of osteoblast genes, type I collagen, osteopontin, bone sialoprotein, and osteocalcin in MC3T3-E1 cells. Conclusions: These studies show that histone deacetylase activity regulates osteoblast differentiation and bone formation at least in part by enhancing Runx2-dependent transcriptional activation. Therefore, HDIs are a potentially new class of bone anabolic agents that may be useful in the treatment of diseases that are associated with bone loss such as osteoporosis and cancer.

Identification of high-risk individuals for hip fracture: a 14-year prospective study.

Abstract: In this 14-year prospective study, men and women were found to share a common set of risk factors for hip fracture: low BMD, postural instability and/or quadriceps weakness, a history of falls, and prior fracture. The combination of these risk factors accounted for 57% and 37% of hip fractures in women and men, respectively. Introduction: Risk factors for hip fracture, including low BMD, identified in women, have not been shown to be useful in men. It is also not known whether fall-related factors (muscle strength and postural instability) predict hip fracture. This study examined the association between falls-related factors and hip fractures in elderly men and women. Materials and Methods: This is an epidemiologic, community-based prospective study, which included 960 women and 689 men ≥60 years of age who have been followed for a median of 12 years (interquartile range, 6–13). The number of person-years was 9961 for women and 4463 for men. The outcome measure was incidence of hip fracture. Risk factors were femoral neck BMD (FNBMD), postural sway, quadriceps strength, prior fracture, and fall. Results: Between 1989 and 2003, 115 (86 women) sustained a hip fracture. The risk of hip fracture (as measured by hazards ratio [HR]) was increased by 3.6-fold (95% CI: 2.6–4.5) in women and 3.4-fold (95% CI: 2.5–4.6) in men for each SD (0.12 g/cm2) reduction in FNBMD. After adjusting for BMD, the risk of hip fracture was also increased in individuals with the highest tertile of postural sway (HR: 2.7; 95% CI: 1.6–4.5) and low tertiles of quadriceps strength (HR: 3.0; 95% CI: 1.3–6.8). Furthermore, a history of fall during the preceding 12 months and a history of fracture were independent predictors of hip fracture. For each level of BMD, the risk of hip fracture increased linearly with the number of non-BMD risk factors. Approximately 57% and 37% of hip fracture cases in women and men, respectively, were attributable to the presence of risk factors, osteoporosis (BMD T score ≤ −2.5), and advancing age. Conclusions: Men and women had a common set of risk factors for hip fracture: low BMD, postural instability and/or quadriceps weakness, a history of falls, and prior fracture. Preventive strategies should simultaneously target reducing falls and improvement of bone strength in both men and women.