bluuebunny/crossref_metadata_2025 huggingface dataset:
Ubiquitin-Associated Domain Mutations of SQSTM1 in Paget's Disease of Bone: Evidence for a Founder Effect in Patients of British Descent
Authors: Lucas Gavin JA , Hocking Lynne J , Daroszewska Anna , Cundy Tim , Nicholson Geoff C , Walsh John P , Fraser William D , Meier Christian , Hooper Michael J , Ralston Stuart H
Published: April 2006

Mutations in the UBA domain of SQSTM1 are a common cause of Paget's disease of bone. Here we show that the most common disease-causing mutation (P392L) is carried on a shared haplotype, consistent with a founder effect and a common ancestral origin.

Introduction: Paget's disease of bone (PDB) is a common condition with a strong genetic component. Mutations affecting the ubiquitin-associated (UBA) domain of sequestosome 1 (SQSTM1) have recently been shown to be an important cause of PDB. The most common mutation results in a proline to leucine amino acid change at codon 392 (P392L), and evidence has been presented to suggest that there may be a recurrent mutation rather than a founder mutation on an ancestral chromosome. Because marked geographical differences exist in the prevalence of PDB, we have investigated the frequency of SQSTM1 mutations in different populations and looked for a founder effect on chromosomes bearing SQSTM1 UBA domain mutations.

Materials and Methods: We conducted mutation screening of SQSTM1 and performed haplotype analysis using the PHASE software program in 83 kindreds with familial PDB, recruited mainly through clinic referrals in the United Kingdom, Australia, and New Zealand. Similar studies were conducted in 311 individuals with PDB who did not have a family history and 375 age- and sex-matched controls from the United Kingdom.

Results: The proportion of patients with familial PDB who had SQSTM1 UBA domain mutations varied somewhat between referral centers from 7.1% (Sydney, Australia) to 50% (Perth, Australia), but the difference between centers was not statistically significant. Haplotype analysis in 311 British patients with PDB who did not have a family history and 375 age- and sex-matched British controls showed that two common haplotypes accounted for about 90% of alleles at the SQSTM1 locus, as defined by common single nucleotide polymorphisms (SNPs) in exon 6 (C916T, G976A) and the 3′UTR (C2503T, T2687G). These were H1 (916T-976A-2503C-2687T) and H2 (916C-976G-2503T-2687G). There was no significant difference in haplotype distribution in PDB cases and controls, but the P392L mutation was found on the H2 haplotype in 25/27 cases (93%), which is significantly more often than expected given the allele frequencies in the normal population (odds ratio, 13.2; 95% CI, 3.1-56.4; p < 0.0001). Similar findings were observed in familial PDB, where 12/13 (92%) of P392L mutations were carried on H2 (odds ratio 17.2; 95% CI, 2.2-138; p = 0.001).

Conclusions: These results provide strong evidence for a founder effect of the SQSTM1P392L mutation in PDB patients of British descent, irrespective of family history. Our results imply that these individuals share a common ancestor and that the true rate of de novo mutations may be lower than previously suspected.
Capsaicin-Sensitive Sensory Neurons Contribute to the Maintenance of Trabecular Bone Integrity
Authors: Offley Sarah C , Guo Tian-Zhi , Wei Tzuping , Clark J David , Vogel Hannes , Lindsey Derek P , Jacobs Christopher R , Yao Wei , Lane Nancy E , Kingery Wade S
Published: April 2006

This investigation used capsaicin to selectively lesion unmyelinated sensory neurons in rats. Neuronal lesioning induced a loss of trabecular integrity, reduced bone mass and strength, and depleted neuropeptides in nerve and bone. These data suggest that capsaicin-sensitive sensory nerves contribute to trabecular bone integrity.

Introduction: Familial dysautomia is an autosomal recessive disease in which patients suffer from unmyelinated sensory neuron loss, reduced BMD, and frequent fractures. It has been proposed that the loss of neurotransmitters synthesized by unmyelinated neurons adversely affects bone integrity in this hereditary syndrome. The purpose of this study was to determine whether small sensory neurons are required for the maintenance of bone integrity in rats.

Materials and Methods: Ten-month-old male Sprague-Dawley rats were treated with either capsaicin or vehicle. In vivo DXA scanning and μCT scanning, and histomorphometry were used to evaluate BMD, structure, and cellular activity. Bone strength was measured in distal femoral sections. Body weight and gastrocnemius/soleus weights were measured and spontaneous locomotor activity was monitored. Peroneal nerve morphometry was evaluated using light and electron microscopy. Substance P and calcitonin gene-related peptide (CGRP) content in the sciatic nerve and proximal tibia were determined by enzyme immunoassay (EIA). Substance P signaling was measured using a sciatic nerve stimulation extravasation assay.

Results: Four weeks after capsaicin treatment, there was a loss of BMD in the metaphyses of the tibia and femur. In the proximal tibia, the osteoclast number and surface increased, osteoblast activity and bone formation were impaired, and trabecular bone volume and connectivity were diminished. There was also a loss of bone strength in the distal femur. No changes occurred in body weight, 24-h grid-crossing activity, weight bearing, or muscle mass after capsaicin treatment, indicating that skeletal unloading did not contribute to the loss of bone integrity. Capsaicin treatment destroyed 57% of the unmyelinated sensory axons, reduced the substance P and CGRP content in the sciatic nerve and proximal tibia, and inhibited neurogenic extravasation.

Conclusion: These results support the hypothesis that capsaicin-sensitive sensory neurons contribute to the maintenance of trabecular bone integrity. Capsaicin-sensitive neurons have efferent functions in the tissues they innervate, effects mediated by transmitters released from the peripheral nerve terminals. We postulate that the deleterious effects of capsaicin treatment on trabecular bone are mediated by reductions in local neurotransmitter content and release.
Effect of CYP1A1 Gene Polymorphisms on Estrogen Metabolism and Bone Density
Authors: Napoli Nicola , Villareal Dennis T , Mumm Steven , Halstead Linda , Sheikh Sharmin , Cagaanan Manuel , Rini Giovam Battista , Armamento-Villareal Reina
Published: April 2006

In this study, we evaluated the effect of polymorphisms of the CYP1A1 gene, linked to hormone-related cancers, on estrogen metabolism and BMD. We found that variants carrying the A allele (CA and AA) for the C4887A polymorphism have a significantly higher degree of estrogen catabolism and lower femoral BMD.

Introduction: Polymorphisms of the CYP1A1 gene, one of the key enzymes that metabolize estrogen, have been linked with hormone-related cancers. We investigated the impact of these polymorphisms on estrogen metabolism and BMD, which is another hormone-dependent health issue.

Materials and Methods: One hundred seventy postmenopausal women (mean age, 63.5 ± 0.6 years) participated in the study, but analysis was limited to 156 white women. Genotyping was performed by restriction fragment length polymorphism analysis, urinary estrogen metabolites by enzyme immunoassay, serum estradiol by ultrasensitive radioimmunoassay, serum sex hormone-binding globulin by immunoradiometric assay, and BMD by DXA. Differences in the levels of urinary metabolites and BMD among the different variants were analyzed by analysis of covariance, whereas differences in free estradiol index, urinary N-telopeptide of type 1 collagen (NTx), and bone size were compared by one-way ANOVA.

Results: We found that subjects carrying the A allele (CA or AA) for the C4887A polymorphism of the CYP1A1 gene have significantly lower free estradiol index (0.323 ± 0.08 versus 0.506 ± 0.04; p = 0.04; pmol/nmol) and higher levels of total urinary estrogen metabolites (ng/mg Cr) than CC subjects (27.92 ± 2.03 versus 21.15 ± 1.04; p = 0.03), suggestive of an accelerated estrogen catabolism in these (CA + AA) individuals. They also had significantly lower BMD (g/cm2) in all regions of the femur than subjects with the CC genotype, (total hip: 0.809 ± 0.02 versus 0.865 ± 0.01; neck: 0.671 ± 0.02 versus 0.722 ± 0.01; trochanter: 0.614 ± 0.02 versus 0.656 ± 0.01; and intertrochanter: 0.969 ± 0.03 versus 1.039 ± 0.01; all p < 0.05). No significant effect of this gene polymorphism was detected on lumbar spine BMD. Urinary NTx, a marker for bone resorption, was also significantly higher in the CA + AA compared with the CC variants (186.09 ± 16.15 versus 124.00 ± 11.87 nmol of bone collagen equivalent/mmol of creatinine; p = 0.003). Genotype frequencies for this polymorphism showed CC as the most common genotype (127/156), followed by CA (28/156), whereas AA was rare (1/156).

Conclusion: Women with the A allele seem to have increased estrogen catabolism, as indicated by higher urinary estrogen metabolites and lower free estradiol index. This is associated with increased bone resorption and lower femoral BMD in those with the A allele. Our data, therefore, suggest that, through its effect on the rate of estrogen catabolism, the C4887A polymorphism of the CYP1A1 gene may represent a possible genetic risk factor for osteoporosis.
An Instrument to Measure Skeletal Burden and Predict Functional Outcome in Fibrous Dysplasia of Bone
Authors: Collins Michael T , Kushner Harvey , Reynolds James C , Chebli Caroline , Kelly Marilyn H , Gupta Anurag , Brillante Beth , Leet Arabella I , Riminucci Mara , Robey Pamela Gehron , Bianco Paolo , Wientroub Shlomo , Chen Clara C
Published: April 2006

An instrument to measure skeletal burden in fibrous dysplasia was developed. Biological and clinical relevance was shown by correlating skeletal burden scores with bone markers, quality of life, and ambulatory status. Childhood scores predict adult ambulatory status, and scores were unaffected when bone markers decreased with bisphosphonate treatment or aging.

Introduction: Fibrous dysplasia (FD) is a skeletal disease with a broad clinical expression. There is no objective method to assess the extent of skeletal involvement or predict outcome. We developed an instrument to measure skeletal burden that correlates with physical function, health-related quality of life (HRQL), and ambulatory status.

Materials and Methods: Seventy-nine patients with FD underwent bone scintigraphy. The skeletal burden score was derived from a weighted score based on the regional measurement using bone scintigraphy to estimate the amount of FD in anatomical segments. Six readers scored 20 scans twice to determine the inter- and intrareader agreement. To assess biological significance, scores were correlated with bone markers. To assess functional outcome, scores on the SF-36 (adults) or CHQ-PF50 (children) were correlated with skeletal burden scores. In a group of patients who had bone scans as children and adults (n = 6), the ability to predict ambulatory status was tested. Skeletal burden scores were assessed in patients before and after treatment with pamidronate (n = 5).

Results: The inter- and intrareader agreement of burden scores were r = 0.96, and 0.98, respectively (p < 0.001 for both). The scores correlated with markers of bone metabolism and HRQL (Spearman rho, 0.54-0.67 p < 0.001 and −0.43, p = 0.001, respectively). The mean score of patients who ambulated unassisted was significantly lower than those requiring assistance (p < 0.001 unassisted versus crutch and/or wheelchair). In unassisted ambulators, younger patients had higher scores, suggesting high childhood scores may predict adulthood impairment. In six patients with childhood and adulthood scans, childhood scores >30 predicted assisted ambulation in adulthood. There was a negative correlation between bone markers and age (Spearman rho, −0.42 to −0.70; p < 0.001), but not age and skeletal burden score. Pamidronate treatment decreased serum alkaline phosphatase but had no effect on the skeletal burden score.

Conclusions: This is a validated and reliable instrument for the measurement of skeletal burden of FD and is able to predict functional outcome.
Alveolar Bone Marrow as a Cell Source for Regenerative Medicine: Differences Between Alveolar and Iliac Bone Marrow Stromal Cells
Authors: Matsubara Takehiro , Suardita Ketut , Ishii Masakazu , Sugiyama Masaru , Igarashi Akira , Oda Ryo , Nishimura Masahiro , Saito Masahiro , Nakagawa Keigo , Yamanaka Katsuyuki , Miyazaki Kazuko , Shimizu Masakazu , Bhawal Ujjal K , Tsuji Koichiro , Nakamura Kozo , Kato Yukio
Published: April 2006

We isolated and expanded BMSCs from human alveolar/jaw bone at a high success rate (70%). These cells had potent osteogenic potential in vitro and in vivo, although their chondrogenic and adipogenic potential was less than that of iliac cells.

Introduction: Human bone marrow stromal cells (BMSCs) have osteogenic, chondrogenic, and adipogenic potential, but marrow aspiration from iliac crest is an invasive procedure. Alveolar BMSCs may be more useful for regenerative medicine, because the marrow can be aspirated from alveolar bone with minimal pain.

Materials and Methods: In this study, alveolar bone marrow samples were obtained from 41 patients, 6–66 years of age, during the course of oral surgery. BMSCs were seeded and maintained in culture with 10% FBS and basic fibroblast growth factor. In addition, BMSCs were induced to differentiate into osteoblasts, chondrocytes, or adipocytes in appropriate medium.

Results and Conclusion: From a small volume (0.1–3 ml) of aspirates, alveolar BMSCs expanded at a success ratio of 29/41 (70%). The success rate decreased with increasing donor age, perhaps because of age-dependent decreases in the number and proliferative capacity of BMSCs. The expanded BMSCs differentiated into osteoblasts under osteogenic conditions in 21–28 days: the mRNA levels of osteocalcin, osteopontin, and bone sialoprotein, along with the calcium level, in alveolar BMSC cultures were similar to those in iliac cultures. However, unlike iliac BMSC, alveolar BMSC showed poor chondrogenic or adipogenic potential, and similar differences were observed between canine alveolar and iliac BMSCs. Subsequently, human alveolar BMSCs attached to β-tricalcium phosphate were transplanted into immunodeficient mice. In transplants, new bone formed with osteoblasts and osteocytes that expressed human vimentin, human osteocalcin, and human GAPDH. These findings suggest that BMSCs have distinctive features depending on their in vivo location and that alveolar BMSCs will be useful in cell therapy for bone diseases.
Expression of Runx2/Cbfa1/Pebp2αA During Angiogenesis in Postnatal Rodent and Fetal Human Orofacial Tissues
Authors: Bronckers Antonius LJJ , Sasaguri Kenichi , Cavender Adriana C , D'Souza Rena N , Engelse Marten A
Published: April 2006

Transient expression of Runx2 is reported in endothelial cells and vascular smooth muscle cells during vessel formation in skin, stroma of forming bones and developing periodontal ligament, developing skeletal muscle cells, and fat tissue. The data suggest that Runx2 is expressed in a multipotential mesenchymal cell population that gives rise to various osseous and nonosseous cell lineages.

Introduction: Runx2/Cbfa1 is a transcription factor essential for cells of osteogenic and dentinogenic lineages. Here we examined expression of Runx2/Cbfa1 (all isotypes) in several nonskeletal cell types present in developing orofacial tissues of neonatal rodents and human fetuses with special emphasis on vessel formation.

Materials and Methods: Sections obtained from heads or jaws of postnatal mice, hamster, and human fetuses were immunostained with monoclonal anti-Pebp2aA antibody. Mouse and human tissues were also examined by in situ hybridization. Sections of Runx2 null mutant mice with a LacZ reporter construct inserted in the Runx2 locus were stained for Runx2 promoter activity with anti-galactosidase.

Results: We found transient mRNA and protein expression in endothelial cells and in vascular smooth muscle cells of forming vessels in skin, alveoli of forming bone, and forming periodontal ligament. We also noticed weak and variable expression in some fibroblasts of embryonic skin, early differentiating cross-striated muscle cells, and differentiating fat cells.

Conclusion: Runx2 is not an exclusive marker for chondrogenic, osteogenic, and dentinogenic tissues, but is much more widely present in an early multipotential mesenchymal cell population that gives rise to several other lineages.
Femoral Neck Structure in Adult Female Athletes Subjected to Different Loading Modalities
Authors: Nikander Riku , Sievänen Harri , Heinonen Ari , Kannus Pekka
Published: April 2006

Loading modality is a strong external determinant of structure and concomitant strength of the femoral neck. Particularly effective seem to be loadings, which arise from high impacts or impacts from atypical loading directions.

Introduction: Physical loading plays an important role, not only in the process of bone modeling and remodeling, but also in shaping a mechanically appropriate bone structure. This study aimed at testing the hypothesis that the type of loading partly determines the femoral neck structure.

Materials and Methods: A total of 255 premenopausal female athletes representing volleyball, hurdling, squash-playing, soccer, speed skating, step aerobics, weight-lifting, orienteering, cross-country skiing, cycling, and swimming and their 30 nonathletic counterparts were measured with DXA. Besides the conventional areal BMD (aBMD) of the femoral neck, the hip structure analysis (HSA) was used to estimate the cross-sectional area (CSA), subperiosteal width (W), and section modulus (Z, an index of bone strength) at the narrowest section of the femoral neck. Also, training history, muscle strength, and calcium intake were assessed. The above-mentioned sports were classified according to the type of loading they apparently produce at the hip region; that is, high-impact loading (volleyball, hurdling), odd-impact loading (squash-playing, soccer, speed-skating, step aerobics), high-magnitude loading (weightlifting), low-impact loading (orienteering, cross-country skiing), and nonimpact loading (swimming, cycling).

Results: High-impact and odd-impact loading sports were associated with the highest age-, weight-, and height-adjusted aBMD (23% and 29% higher values compared to nonathletic referents), CSA (22% and 27%), and Z (22% and 26%). In contrast, repetitive, nonimpact loading sports were not associated with any clear benefit in any bone value compared with the referents. The W at the narrowest femoral neck section was similar in all groups. Body height and weight accounted virtually for one-half of the variation in Z, whereas the type of loading predicted 13% of the total variation of this variable—clearly more than the 2% attributable to isometric leg extension strength. Both high-impact and odd-impact loading modalities were associated with a large benefit in Z, corresponding to >1 SD in the reference group, whereas repetitive, low-impact loading showed a benefit that was only one-half of that. Surprisingly, high-magnitude loading (weightlifting) was not associated with a statistically significant increase in Z.

Conclusion: We conclude that mechanical loading and its modality are strong external determinants of structure and concomitant strength of the femoral neck. Particularly effective seem to be loadings, which arise from high impacts or impacts from atypical loading directions.
Mechanism and Function of High Vitamin D Receptor Levels in Genetic Hypercalciuric Stone-Forming Rats
Authors: Karnauskas Alexander J , van Leeuwen Johannes PTM , van den Bemd Gert-Jan CM , Kathpalia Paru P , DeLuca Hector F , Bushinsky David A , Favus Murray J
Published: April 2006

The functional status and mechanism of increased VDR in GHS rats were investigated. Basal VDR and calbindins were increased in GHS rats. 1,25(OH)2D3 increased VDR and calbindins in controls but not GHS rats. VDR half-life was prolonged in GHS rats. This study supports the mechanism and functional status of elevated VDR in GHS rats.

Introduction: Genetic hypercalciuric stone-forming (GHS) rats form calcium kidney stones from hypercalciuria arising from increased intestinal calcium absorption and bone resorption and decreased renal calcium reabsorption. Normal serum 1,25-dihydroxyvitamin D3 ‘1,25(OH)2D3’ levels and increased vitamin D receptor (VDR) protein suggest that high rates of expression of vitamin D-responsive genes may mediate the hypercalciuria. The mechanism of elevated VDR and state of receptor function are not known.

Materials and Methods: GHS and non-stone-forming control (NC) male rats (mean, 249 g), fed a normal calcium diet, were injected intraperitoneally with 1,25(OH)2D3 (30 ng/100 g BW) or vehicle 24 h before cycloheximide (6 mg/100 g, IP) and were killed 0–8 h afterward. Duodenal VDR was measured by ELISA and Western blot, and duodenal and kidney calbindins (9 and 28 kDa) were measured by Western blots.

Results and Conclusions: Duodenal VDR protein by Western blot was increased 2-fold in GHS versus NC rats (633 ± 62 versus 388 ± 48 fmol/mg protein, n = 4, p < 0.02), and 1,25(OH)2D3 increased VDR and calbindins (9 and 28 kDa) further in NC but not GHS rats. Duodenal VDR half-life was prolonged in GHS rats (2.59 ± 0.2 versus 1.81 ± 0.2 h, p < 0.001). 1,25(OH)2D3 prolonged duodenal VDR half-life in NC rats to that of untreated GHS rats (2.59 ± 0.2 versus 2.83 ± 0.3 h, not significant). This study supports the hypothesis that prolongation of VDR half-life increases VDR tissue levels and mediates increased VDR-regulated genes that result in hypercalciuria through actions on vitamin D-regulated calcium transport in intestine, bone, and kidney.
Effects of Low-Dose Prednisone on Bone Metabolism
Authors: Ton Francine N , Gunawardene Samantha C , Lee Hang , Neer Robert M
Published: April 2006

Prednisone 5 mg/day suppresses multiple indices of bone formation in a randomized placebo-controlled trial in healthy postmenopausal females. This suggests that even low doses of prednisone may reduce bone repair or renewal and may have adverse effects on bone mass and/or bone strength.

Introduction: High doses of chronic glucocorticoids are known to have adverse effects on bone, and measures to prevent bone loss are well established for doses >7.5 mg daily, because these doses can cause premature or exaggerated osteoporosis. However, it is unclear if chronic prednisone doses of 5 mg daily have the same effects on bone. There are no established recommendations for preventing glucocorticoid-induced osteoporosis in people taking prednisone 5 mg daily, a dose used frequently in medical practice to treat diseases of the lungs, joints, skin, muscles, eyes, nerves, etc. Our primary objective was to test whether prednisone 5 mg daily affects serum and urine indices of bone metabolism in healthy postmenopausal women. Our secondary objectives were to determine if prednisone 5 mg affected systolic or diastolic blood pressure or causes side effects.

Materials and Methods: A double-blinded randomized placebo-controlled 8-week trial in 50 healthy postmenopausal women was conducted at the Massachusetts General Hospital Outpatient General Clinical Research Center. Patients were randomly assigned to prednisone 5 mg daily or matching placebo for 6 weeks, followed by a 2-week recovery phase. Markers of bone formation and resorption were determined at weeks 0, 2, 4, 6, and 8. Indices of osteoblast activity included serum propeptide of type I N-terminal procollagen (PINP), propeptide of type I C-terminal procollagen (PICP), osteocalcin, and bone-specific alkaline phosphatase (BSALP). Indices of osteoclast activity included urine and serum type I collagen N-telopeptide (NTX) and free urinary deoxypyridinoline (DPD).

Results and Conclusions: Prednisone rapidly and significantly decreased serum PINP (p < 0.01), PICP (p < 0.01), and osteocalcin (p < 0.01) and free urinary deoxypyridinoline (p = 0.017). These changes were largely reversed during the recovery period. Side effects were indistinguishable in the two groups. Neither systolic nor diastolic blood pressure changed significantly throughout the study between the two groups. In conclusion, low-dose prednisone significantly decreases indices of bone formation and may decrease indices of bone resorption in postmenopausal women. Further studies are needed to assess the effects of low-dose prednisone on BMD and fracture risk.
Initial Years of Recreational Artistic Gymnastics Training Improves Lumbar Spine Bone Mineral Accrual in 4- to 8-Year-Old Females
Authors: Laing Emma M , Wilson Alissa R , Modlesky Christopher M , O'Connor Patrick J , Hall Daniel B , Lewis Richard D
Published: April 2006

Gymnasts' bone mineral characteristics are generally not known before starting their sport. Prepubertal females who enrolled in beginning artistic gymnastics (n = 65) had lower bone mineral than controls (n = 78). However, 2 years of gymnastics participation versus no participation led to a significantly greater accrual of forearm bone area and lumbar spine areal BMD.

Introduction: The skeletal response to exercise in children compared with adults is heightened because of the high bone turnover rate and the ability of bone to change its size and shape. Whereas child gymnasts generally have greater rates of bone mineral accrual compared with nongymnasts, it is unknown if some of these skeletal advantages are present before the onset of training or are caused entirely by training.

Materials and Methods: Changes in bone area (BA; cm2), BMC (g), and areal BMD (aBMD; g/cm2) over 24 months were examined in prepubertal females, 4–8 years of age, who selected to perform recreational gymnastics (GYM; n = 65), nongymnastic activities, or no organized activity (CON; n = 78). Participants had essentially no lifetime history of organized athletic participation (<12 weeks). Pubertal maturation was assessed annually by a physician. Total body, lumbar spine, total proximal femur, and forearm BA, BMC, and aBMD were measured every 6 months using DXA (Hologic QDR-1000W). Independent samples t-tests determined baseline group differences. Nonlinear mixed effects models were used to model 24-month changes in bone data. In subset analyses, high-level gymnasts advancing to competition (HLG; n = 9) were compared with low-level nonadvancing gymnasts (LLG; n = 56).

Results: At baseline, GYM were shorter, lighter, and had lower BA, BMC, and aBMD compared with CON (p < 0.05), whereas HLG did not differ significantly in these measurements compared with LLG (p > 0.05). Controlling for differences in race, baseline measures of body mass, height, and calcium intake, and change in breast development beyond stage II at 24 months, GYM had greater long-term (asymptotic) mean responses for total body aBMD and forearm BMC (p < 0.04) and greater rates of increase in the mean responses of lumbar spine aBMD and forearm BA compared with CON over 24 months. Over time, forearm BA increased to a greater extent in HLG compared with LLG (p < 0.01).

Conclusions: Females participating in recreational gymnastics initiated during childhood have enhanced bone mineral gains at the total body, lumbar spine, and forearm over 24 months. Higher-level training promotes additional gains in forearm BA.
Nonreplication in Genetic Studies of Complex Diseases—Lessons Learned From Studies of Osteoporosis and Tentative Remedies
Authors: Shen Hui , Liu Yongjun , Liu Pengyuan , Recker Robert R , Deng Hong-Wen
Published: April 2006

Inconsistent results have accumulated in genetic studies of complex diseases/traits over the past decade. Using osteoporosis as an example, we address major potential factors for the nonreplication results and propose some potential remedies.

Over the past decade, numerous linkage and association studies have been performed to search for genes predisposing to complex human diseases. However, relatively little success has been achieved, and inconsistent results have accumulated. We argue that those nonreplication results are not unexpected, given the complicated nature of complex diseases and a number of confounding factors. In this article, based on our experience in genetic studies of osteoporosis, we discuss major potential factors for the inconsistent results and propose some potential remedies. We believe that one of the main reasons for this lack of reproducibility is overinterpretation of nominally significant results from studies with insufficient statistical power. We indicate that the power of a study is not only influenced by the sample size, but also by genetic heterogeneity, the extent and degree of linkage disequilibrium (LD) between the markers tested and the causal variants, and the allele frequency differences between them. We also discuss the effects of other confounding factors, including population stratification, phenotype difference, genotype and phenotype quality control, multiple testing, and genuine biological differences. In addition, we note that with low statistical power, even a “replicated” finding is still likely to be a false positive. We believe that with rigorous control of study design and interpretation of different outcomes, inconsistency will be largely reduced, and the chances of successfully revealing genetic components of complex diseases will be greatly improved.
Fracture Risk With Multiple Myeloma: A Population-Based Study
Authors: Melton L Joseph , Kyle Robert A , Achenbach Sara J , Oberg Ann L , Rajkumar S Vincent
Published: April 2006

Pathologic fractures, especially of the axial skeleton, are extremely common in patients with multiple myeloma and cluster around the time of diagnosis. Osteoporotic fractures seem to be less of a problem in these patients.

Introduction: It is generally believed that fractures are common in patients with multiple myeloma as a result of lytic bone lesions, generalized bone loss, and/or elevated bone turnover from excessive cytokine production, but the actual risk of pathologic versus osteoporotic fractures has not been quantified.

Materials and Methods: In a population-based retrospective cohort study, 165 Olmsted County, MN, residents with myeloma diagnosed from 1945 to 2001 (55% men; mean age, 70.7 ± 11.1 years) were followed for 537 person-years. The relative risk of fractures was assessed by standardized incidence ratios (SIRs), and risk factors were evaluated in proportional hazards models.

Results: Altogether, 134 patients experienced 463 fractures. In the year before diagnosis, 16 times more fractures were observed than expected, mostly pathologic fractures of the vertebrae and ribs. Subsequently, there was a 9-fold increase in fracture risk. However, 69% of these fractures were pathologic, and another 11% were found incidentally on myeloma monitoring. With the latter two groups excluded, subsequent fracture risk was elevated 3-fold, with a 2-fold increase in the risk of an osteoporotic fracture. In multivariate analyses, the predictors of overall fracture risk were oral corticosteroid use and elevated serum calcium levels, whereas pathologic fractures were additionally predicted by use of chemotherapy.

Conclusion: There is a dramatic increase in fractures around the time of diagnosis of myeloma, most of which are pathologic fractures. The most important predictor of overall fracture risk is oral corticosteroid use.
Isolation and Characterization of Piscine Osteonectin and Downregulation of Its Expression by PTH-Related Protein
Authors: Redruello Begoña , Estêvão M Dulce , Rotllant Josep , Guerreiro Pedro M , Anjos Liliana I , Canário Adelino VM , Power Deborah M
Published: April 2006

The skeleton is the main source of osteonectin mRNA in adults of the seawater teleost sea bream Sparus auratus. It is expressed by cells forming the basement membrane of calcifying tissue indicating that, as in mammals, it may play a role in osteoblast differentiation. PTHrP induced downregulation of osteonectin mRNA in vitro in scales, a mineralizing tissue with bone-like metabolism. This indicates a means to redirect calcium to activities such as vitellogenesis when this ion is in high demand.

Introduction: Osteonectin is a unique matricellular calcium-binding glycoprotein and a major noncollagenous constituent of higher eukaryote bone. In terrestrial vertebrates, it has been associated with development, remodeling, cell turnover, and tissue repair, all processes involving substantial changes in extracellular matrix (ECM) structure. In skeleton biology, osteonectin has been described as a positive factor in the mineralization process as well as in osteoblastic cell lineage differentiation and is downregulated by the hypercalcemic hormone PTH. In this study, we report the cloning and characterization of bream S. auratus osteonectin cDNA and its tissue and cellular distribution. Its high expression by fish scales provides a unique in vitro bioassay with which to study regulation of osteonectin gene expression by the recently isolated piscine PTH-related peptide (PTHrP).

Materials and Methods: An intervertebral tissue cDNA library from S. auratus was the source of the full-length cDNA clone for osteonectin. Expression studies were performed by semiquantitative RT-PCR, Northern blot, and in situ hybridization analysis. Moreover, an in vitro bioassay with S. auratus scales was specifically developed for measuring the effect of PTHrP on osteonectin expression.

Results and Conclusions: Phylogenetic analysis showed that S. auratus osteonectin is highly homologous with previously reported osteonectins, supporting the idea of a conserved function for this protein in the ECM. Its expression pattern in adult tissues from S. auratus was markedly biased toward skeletal structures of both dermal or endochondral origin. More specifically, the localization of the osteonectin mRNA in the basement membrane that separates the epithelia from the underlying mineralized connective tissue supports a role for this protein in calcified matrix turnover. Furthermore, the recently identified piscine hypercalcemic factor PTHrP downregulates osteonectin expression in scales, suggesting a catabolic action for this hormone on these structures.
β-Blocker Use, BMD, and Fractures in the Study of Osteoporotic Fractures
Authors: Reid Ian R , Gamble Gregory D , Grey Andrew B , Black Dennis M , Ensrud Kristine E , Browner Warren S , Bauer Douglas C
Published: April 2006

A role for osteoblastic β-adrenoreceptors in bone regulation is suggested by the finding that β-blockers increase bone mass in mice. We studied the association of β-blocker use with BMD and fractures in the Study of Osteoporotic Fractures. β-blocker use and BMD are unrelated in this cohort, and associations with fracture risk are inconsistent.

Introduction: The central nervous system has been shown to regulate bone mass in mice, possibly by way of the β2-adrenoreceptors on osteoblasts. β-blockers have been shown to increase bone mass in mice. Because these agents are widely used therapeutically, it is possible that they may influence fracture epidemiology in humans, and they are a potential therapy for osteoporosis.

Materials and Methods: We have studied the association of β-blocker use with BMD and fracture rates in the Study of Osteoporotic Fractures. β-blocker use was recorded at the fourth visit, in 8412 women, of whom 1099 were users, and these women were followed for 7 years.

Results: Users had significantly higher weight, more thiazide use, more estrogen use, less glucocorticoid use, more statin use, and more hypertension than nonusers, and they smoked less. Total hip BMD at the fourth visit was higher in the β-blocker users (0.746 versus 0.735 g/cm2, p = 0.02), but adjustment for weight alone, or together with these other variables, eliminated this difference (p = 0.62). There was no effect of β-blocker use on loss of hip BMD over a mean follow-up of 4 years (p = 0.48). Os calcis BMD at visit 4 was also higher in those taking β-blockers (0.385 versus 0.375 g/cm2, p = 0.005), but weight adjustment eliminated this difference (p = 0.14). The frequencies of hip or any fracture (since age 50) were similar in users and nonusers (p = 0.80 and p = 0.51, respectively). Over a mean follow-up of 7 years, there were 2167 total fractures, including 431 at the wrist and 585 at the hip. Among β-blocker users, hazards ratios were 0.92 (0.81, 1.05) for any fracture, 0.74 (0.54, 1.01) for wrist fracture, and 0.76 (0.58, 0.99) for hip fracture. Adjustment for weight and other factors previously shown to influence hip fracture incidence in this cohort made little difference to the outcome. When fracture data were analyzed for nonselective and β1-selective agents separately, trends toward fewer fractures were confined to the users of selective β1-blockers.

Conclusions: β-blocker use and BMD are unrelated in this cohort, and associations with fracture risk are inconsistent. Therefore, a history of use of these drugs is not useful in assessing fracture risk, nor do they have a role in osteoporosis management at this time. The relationship between β-blocker use and hip fracture deserves further study.
β-Arrestin2 Regulates the Differential Response of Cortical and Trabecular Bone to Intermittent PTH in Female Mice
Authors: Bouxsein Mary L , Pierroz Dominique D , Glatt Vaida , Goddard Deborah S , Cavat Fanny , Rizzoli René , Ferrari Serge L
Published: April 2006

Cytoplasmic arrestins regulate PTH signaling in vitro. We show that female β-arrestin2−/− mice have decreased bone mass and altered bone architecture. The effects of intermittent PTH administration on bone microarchitecture differed in β-arrestin2−/− and wildtype mice. These data indicate that arrestin-mediated regulation of intracellular signaling contributes to the differential effects of PTH at endosteal and periosteal bone surfaces.

Introduction: The effects of PTH differ at endosteal and periosteal surfaces, suggesting that PTH activity in these compartments may depend on some yet unidentified mechanism(s) of regulation. The action of PTH in bone is mediated primarily by intracellular cAMP, and the cytoplasmic molecule β-arrestin2 plays a central role in this signaling regulation. Thus, we hypothesized that arrestins would modulate the effects of PTH on bone in vivo.

Materials and Methods: We used pDXA, μCT, histomorphometry, and serum markers of bone turnover to assess the skeletal response to intermittent PTH (0, 20, 40, or 80 μg/kg/day) in adult female mice null for β-arrestin2 (β-arr2−/−) and wildtype (WT) littermates (7-11/group).

Results and Conclusions: β-arr2−/− mice had significantly lower total body BMD, trabecular bone volume fraction (BV/TV), and femoral cross-sectional area compared with WT. In WT females, PTH increased total body BMD, trabecular bone parameters, and cortical thickness, with a trend toward decreased midfemoral medullary area. In β-arr2−/− mice, PTH not only improved total body BMD, trabecular bone architecture, and cortical thickness, but also dose-dependently increased femoral cross-sectional area and medullary area. Histomorphometry showed that PTH-stimulated periosteal bone formation was 2-fold higher in β-arr2−/− compared with WT. Osteocalcin levels were significantly lower in β-arr2−/− mice, but increased dose-dependently with PTH in both β-arr2−/− and WT. In contrast, whereas the resorption marker TRACP5B increased dose-dependently in WT, 20-80 μg/kg/day of PTH was equipotent with regard to stimulation of TRACP5B in β-arr2−/−. In summary, β-arrestin2 plays an important role in bone mass acquisition and remodeling. In estrogen-replete female mice, the ability of intermittent PTH to stimulate periosteal bone apposition and endosteal resorption is inhibited by arrestins. We therefore infer that arrestin-mediated regulation of intracellular signaling contributes to the differential effects of PTH on cancellous and cortical bone.
Quantitative Ultrasound: Use in Screening for Susceptibility to Stress Fractures in Female Army Recruits
Authors: Lappe Joan , Davies Kennard , Recker Robert , Heaney Robert
Published: April 2006

QUS measurements were made on 4139 female Army recruits at the beginning of basic training (BT). QUS predicted stress fracture in female recruits as well as it predicts hip fracture in elderly women. Recruits with low QUS values and a history of smoking and not exercising had an extremely high risk of stress fracture.

Introduction: Stress fractures during basic military training (BT) cause morbidity for the recruits and expense for the Military Services. Females have a higher incidence than males. If recruits at high risk for stress fracture could be accurately identified before they began BT, the military might find it advantageous to provide adaptive training programs for them. Currently no accurate methods of risk identification are available. We measured quantitative ultrasound (QUS) in a population sample of female Army recruits to determine if QUS is a useful tool for determining soldiers at high risk of stress fracture during BT.

Materials and Methods: We recruited 93% of the population of female recruits entering BT at Fort Leonard Wood, MO, during a 10-month period. We measured calcaneal QUS and administered a risk factor questionnaire at baseline and ascertained stress fractures during the 8 weeks of BT. Logistic regression was used to calculate relative risk (RR) of stress fracture. The area under the receiver-operating characteristic (ROC) curve was also analyzed to determine the sensitivity and specificity of speed of sound (SOS) in predicting stress fracture.

Results: The incidence of stress fracture was 4.7%. SOS was significantly related to the risk of stress fracture. (p < 0.000) The area under the ROC curve was 0.70. The relative risk (RR) of fracture of those in the lowest quintile (Q1) of SOS was 6.7. The highest risk of stress fracture was found in the subgroup of white women in Q1 of SOS who smoked and didn't exercise (RR, 14.4). Over 16% of the fractures occurred in this subgroup, which indicates that about six of these women would need to be assigned to an alternate BT regimen to prevent one stress fracture.

Conclusions: The combination of QUS measurements with evaluation of individual risk factors can identify recruits who are at the very highest risk of stress fracture. The military may find these data helpful to determine the cost-effectiveness of alternate BT regimens.
Underdiagnosis of Vertebral Fractures Is a Worldwide Problem: The IMPACT Study
Authors: Delmas Pierre D , van de Langerijt Lex , Watts Nelson B , Eastell Richard , Genant Harry , Grauer Andreas , Cahall David L
Published: April 2006

Accurate radiographic diagnosis of vertebral fractures is important. This multicenter, multinational study assessed radiographic diagnoses of vertebral fracture in 2451 postmenopausal women with osteoporosis. Comparison between local and central readings yielded a false-negative rate of 34%. Underdiagnosis of vertebral fracture is a worldwide problem.

Introduction: Vertebral fractures are the most common complication of osteoporosis. Although they are associated with significant morbidity, they frequently do not come to clinical attention. Accurate radiographic diagnosis is important.

Materials and Methods: In a multicenter, multinational prospective study (the IMPACT trial), the accuracy of radiographic diagnosis of vertebral fracture was evaluated in postmenopausal women 65–80 years of age newly diagnosed with osteoporosis (based on BMD measurement). Lateral radiographs of the thoracolumbar spine were evaluated for identification of vertebral fractures, first locally and subsequently at a central reading center, using a validated semiquantitative method. False-positive and false-negative rates were calculated based on adjudicated discrepancies between the initial interpretation at the local site and the subsequent central reading, considered the “reference standard.”

Results: Of 2451 women with an evaluable radiograph both centrally and locally, 789 (32%) had at least one vertebral fracture. Adjudicated discrepancies (n = 350 patients) between local and central readings because of undetected vertebral fracture (68%) or equivocal terminology in the local radiology report (32%) yielded a false-negative rate of 34%.

Conclusions: Underdiagnosis of vertebral fractures was observed in all geographic regions (false-negative rates: North America, 45.2%; Latin America, 46.5%; Europe/South Africa/Australia, 29.5%). The false-positive rate was 5% globally. Underdiagnosis of vertebral fracture is a worldwide problem attributable in part to a lack of radiographic detection, use of ambiguous terminology in the radiology report, or both. Efforts to improve accuracy and reduce variability in terminology and interpretation may increase the effectiveness of spinal radiography for detecting vertebral fractures in patients with osteoporosis.
Long-Term Fracture Risk Among Children With Asthma: A Population-Based Study
Authors: Melton L Joseph , Patel Ashok , Achenbach Sara J , Oberg Ann L , Yunginger John W
Published: April 2006

Fracture risk among patients diagnosed with asthma in childhood is greater in males and oral corticosteroid users, but most fractures are of the appendicular skeleton and may relate to impaired skeletal development.

Introduction: There are no population-based data on fracture outcomes among the growing number of patients with asthma diagnosed in childhood.

Materials and Methods: We conducted a population-based retrospective (historical) cohort study among 279 Rochester, Minnesota, residents who were <35 years of age (mean, 6.2 years) when first diagnosed with asthma. Fractures were ascertained by review of comprehensive community medical records, and cases were compared directly with age- and sex-matched controls in a stratified proportional hazards model. Risk factors for fractures among the asthma cases were assessed using Andersen-Gill time-to-fracture regression models.

Results: During 6649 person-years of follow-up (median, 24.3 years/subject), 107 asthma patients experienced 189 fractures, for a crude fracture incidence rate of 2.8 per 100 person-years. The actuarially estimated cumulative fracture incidence after 20 years was 40% compared with 34% among controls (p = 0.122). There was no significant increase in overall fracture risk among cases compared to their age- and sex-matched controls (hazard ratio [HR], 1.3; 95% CI, 0.9-1.9), but males with asthma had a 2.6-fold greater risk of hand and finger fractures than control males. The independent predictors of overall fracture risk among the asthma patients included male gender (HR, 2.2; 95% CI, 1.5-3.2) and use of oral corticosteroids (HR, 2.0; 95% CI, 1.2-3.1) or anti-cholinergic agents (HR, 3.9; 95% CI, 1.5-10).

Conclusions: Rather than osteoporotic fractures of the axial skeleton, oral corticosteroid therapy was associated here with limb fractures, suggesting a relationship with impaired development of a biomechanically competent skeleton. Additional studies are needed to assess this possibility.