bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intravenous Neridronate in Children With Osteogenesis Imperfecta: A Randomized Controlled Study
Authors: Gatti Davide , Antoniazzi Franco , Prizzi Rosangela , Braga Vania , Rossini Maurizio , Tatò Luciano , Viapiana Ombretta , Adami Silvano 
Published: April 2006

Abstract
In a randomized controlled study, we investigated the effect of treatment with intravenous neridronate in prepubertal children with OI. Our study suggests that quarterly intravenous infusions of the bisphosphonate significantly raise the rate of increase in BMD at both the spine and hip, the projected area of the lumbar vertebrae, and height. These results are associated with a significant decrease in the risk of clinical fractures.
Introduction: Osteogenesis imperfecta (OI) is a heritable disease of connective tissue, characterized by increased bone fragility. Bisphosphonates currently seem to be the most promising therapy, but randomized, controlled studies are scarce and have never been carried out in prepubertal children.
Materials and Methods: This was a randomized, controlled 3-year clinical trial. The Italian Patients' Society of OI (AsItOI) sent their members affected by any type of OI to two centers at the University of Verona (Italy) to participate in the study. Sixty-four children, 6-11 years of age for boys and 6-9 years of age for girls, with no signs of puberty and who were never treated with bisphosphonates, were randomized to either intravenous neridronate (2 mg/kg infused IV in 30 minutes every 3 months) or no treatment, with a ratio of 2:1. Control patients were given the same bisphosphonate therapy at the end of the first year. BMD and projected bone areas, as measured by DXA, at spine and hip, height, and peripheral fracture incidence, both prospective and retrospective (2 years preceding randomization), were the main outcomes of the study.
Results: At the end of the first year, spine and hip BMD rose by 3.5-5.7% in control patients and by 18-25% (p &lt; 0.001 versus controls) in the active group, respectively. During the following 2 years, the treatment in all patients was associated with BMD increases of 10-25% per year. Height and the DXA-derived projected area of lumbar spine rose during the first year of observation significantly more in the active group than in the control group (&lt;0.01 and &lt;0.05, respectively). Both height and spine projected area continued to rise in the treated patients toward levels found in healthy individuals. During the first year of treatment, 45% of the control patients and 27% of the active group had a nonvertebral fracture, but this difference was not statistically significant (p = 0.2). The total number of fractures was 18 in the 22 control patients and 13 in the active group (relative risk, 0.36; 95% CI, 0.15-0.87; p &lt; 0.05).
Conclusion: Intravenous neridronate infusions, administered quarterly, significantly increase BMD and lower the risk of clinical fracture in prepubertal children with OI.
Genetic Variation in Structure-Function Relationships for the Inbred Mouse Lumbar Vertebral Body
Authors: Tommasini Steven M , Morgan Timothy G , van der Meulen Marjolein CH , Jepsen Karl J 
Published: April 2006

Abstract
Structure-function relationships were determined for L5 vertebral bodies from three inbred mouse strains. Genetic variability in whole bone mechanical properties could be explained by a combination of the traits specifying the amount, distribution, and quality of the cortical and trabecular bone tissue.
Introduction: Although phenotypically correlated with fracture, BMD may be disadvantageous to use in genetic and biomechanical analyses because BMD does not distinguish the contributions of the underlying morphological and compositional bone traits. Developing functional relationships between the underlying bone traits and whole bone mechanical properties should further our understanding of the genetics of bone fragility.
Materials and Methods: Microarchitecture and composition of L5 vertebral bodies (n = 10/strain) from A/J, C57BL/6J, and C3H/HeJ inbred mouse strains were determined using μCT with an isotropic voxel size of 16 μm3. Failure load, stiffness, and total deformation as a measure of ductility were measured in compression using a noncontact strain extensometer imaging system. A correlation analysis related morphological and compositional bone traits to whole bone mechanical properties. A multivariate analysis identified structure-function relationships for each genotype.
Results: No single bone trait accurately explained the genetic variation in mechanical properties. However, a combination of traits describing the amount, distribution, and quality of cortical and trabecular bone tissue explained &gt;70% of the variation in vertebral mechanical properties. Importantly, structure-function relationships were unique among genotypes.
Conclusions: Different genetic backgrounds use different combinations of underlying bone traits to create mechanically functional structures. Using a single complex trait such as BMD or BV/TV as the sole phenotypic marker in genetic analyses may prove to be disadvantageous because of the complex relationship between mechanical properties and the underlying bone traits. Therefore, considering multiple bone traits and the interaction among these bone traits is necessary to understand the relationship between genetic background and complex whole bone mechanical properties.
Comparative Effect of Soy Protein, Soy Isoflavones, and 17β-Estradiol on Bone Metabolism in Adult Ovariectomized Rats
Authors: Cai David J , Zhao Yongdong , Glasier Jennifer , Cullen Diane , Barnes Stephen , Turner Charles H , Wastney Meryl , Weaver Connie M 
Published: April 2006

Abstract
This study provided a comprehensive investigation on the effect of soy protein and soy isoflavones on both calcium and bone metabolism in virgin adult rats. The measurements included bone histology, calcium kinetic modeling, calcium balance, bone densitometry, and whole body densitometry. Results confirmed the bone-preserving effect of estrogen but did not support a bone-sparing role of soy isoflavones.
Introduction: Several animal and short-term human studies have indicated that soy protein isolate enriched with isoflavones may be used as an alternative therapy to estrogen replacement therapy. However, none of the previous studies have investigated this estrogenic effect on both calcium and bone metabolism in animals or humans, which is essential in ascertaining the mode of action of isoflavones.
Materials and Methods: This study was designed to determine the effects of soy protein versus isoflavones on calcium and bone metabolism in an ovariectomized rat model. Unmated 6-month-old ovariectomized and sham-operated female Sprague-Dawley rats were randomly assigned to nine groups (16 rats/group) and pair-fed soy- or casein-based diets with or without isoflavones for 8 weeks. A reference group was administered estrogen through subcutaneous implants (20-35 pg/liter plasma). Bone densitometry, histomorphometry, and mechanical testing were used to study bone metabolism and quality. Calcium metabolism was studied using calcium tracer balance and kinetics.
Results: After ovariectomy, estrogen prevented bone loss in trabecular bone and suppressed formation on both trabecular and cortical bone surfaces. Isoflavones given as enriched soy protein isolate or supplements did not prevent trabecular bone loss. Combining isoflavones with estrogen had no additional benefits over estrogen alone. There were no differences in response to isoflavones caused by protein source. None of the treatments significantly affected either total Ca balance or45Ca absorption. However, soy protein showed significant effects on reducing urinary loss of Ca in animals, irrespective of isoflavone level, perhaps because of the lower amount of sulfur-containing amino acids in soy protein.
Conclusion: Estrogen, but not isoflavones at the levels tested, suppressed bone remodeling in both trabecular and cortical bone after ovariectomy.
Identification of Novel Genetic Loci for Bone Size and Mechanosensitivity in an ENU Mutant Exhibiting Decreased Bone Size
Authors: Srivastava Apurva K , Kapur Sanjay , Mohan Suburaman , Yu Hongrun , Kapur Sonia , Wergedal Jon , Baylink David J 
Published: April 2006

Abstract
Using a dominant ENU mutagenesis screen in C57BL/6J (B6) mice to reveal gene function, we identified a mutant, 917M, with a reduced bone size phenotype, which is expressed only in males. We show that mutation results in osteoblasts with reduced proliferation, increased apoptosis, and an impaired response to in vitro mechanical load. The mutation is mapped to a novel locus (LOD score of 7.9 at 10.5 cM) on chromosome 4.
Introduction: Using a dominant ENU mutagenesis screen in C57BL/6J (B6) mice to reveal gene function, we identified a mutant, 917M, with a reduced bone size phenotype, which is expressed only in males. In this report, we show the chromosomal location of this mutation using linkage analysis and cellular characterization of the mutant phenotype.
Materials and Methods: The mutant mouse was bred to wildtype B6 to produce progeny for characterization of the bone size phenotype. Periosteal osteoblasts isolated from the tibia and femur of mutant and wildtype mice were studied for proliferation, differentiation, and apoptosis potential. To determine the chromosomal location of the mutation, a low-resolution linkage map was established by completing a genome-wide scan in B6C3H F2 male mice generated from intercross breeding of mutant mice.
Results and Conclusions: Mutant progeny (16 weeks old) displayed a total body bone area that was 10-13% lower and a periosteal circumference that was 5-8% lower at the femur and tibia midshaft compared with wildtype B6 mice. Periosteal osteoblasts from mutant mice showed 17-27% reduced cell proliferation and 23% increased apoptosis compared with wildtype controls. In addition, osteoblasts from mutant mice showed an impaired response to shear stress-induced proliferation rate, an in vitro model for mechanical loading. Interval mapping in B6C3H F2 males (n = 69) indicated two major loci affecting bone size on chromosome 1 at 45 cM (LOD 4.9) and chromosome 4 at 10.5 cM (LOD 7.9, genome-wide p &lt; 0.01). Interval mapping using body weight as covariate revealed only one significant interval at chromosome 4 (LOD 6.8). Alleles of the chromosome 4 interval inherited from the B6 mutant strain contributed to a significantly lower bone size than those inherited from C3H. A pairwise interaction analysis showed evidence for a significant interaction between loci on chromosome 1 with the chromosome 4 quantitative trait loci. The 917M locus on chromosome 4 seems to be novel because it does not correspond with those loci previously associated with bone size on chromosome 4 in B6 and C3H/HeJ mice or other crosses.
Heterozygous Mutations in the LDL Receptor-Related Protein 5 (LRP5) Gene Are Associated With Primary Osteoporosis in Children
Authors: Hartikka Heini , Mäkitie Outi , Männikkö Minna , Doria Andrea S , Daneman Alan , Cole William G , Ala-Kokko Leena , Sochett Etienne B 
Published: April 2006

Abstract
Three of 20 patients with juvenile osteoporosis were found to have a heterozygous mutation in the LRP5 gene. No mutations were found in the type I collagen genes. Mutations in the other family members with similar bone phenotype confirmed that LRP5 has a role in both juvenile and adult osteoporosis.
Introduction: The gene encoding the low-density lipoprotein receptor-related protein 5 (LRP5) gene has recently been shown to affect bone mass accrual during growth and to be involved in osteoporosis-pseudoglioma syndrome and a high bone mass phenotype. Mutations in the type I collagen genes (COL1A1 and COL1A2) are known to cause osteogenesis imperfecta, characterized by increased bone fragility.
Materials and Methods: Here we analyzed COL1A1, COL1A2, and LRP5 for mutations in 20 pediatric patients with primary osteoporosis characterized by low BMD, recurrent fractures, and absent extraskeletal manifestations.
Results and Conclusions: No mutations were detected in the type I collagen genes, but two missense mutations (A29T and R1036Q) and one frameshift mutation (C913fs) were found in the LRP5 gene in three of the patients. The frameshift mutation was also seen in the proband's father and brother, who both were found to have significant osteoporosis. R1036Q was observed in the proband's mother and two brothers, who all had osteoporosis. These results indicate that heterozygous mutations in the LRP5 gene can cause osteoporosis in both children and adults.
Leptin Treatment Induces Loss of Bone Marrow Adipocytes and Increases Bone Formation in Leptin-Deficient ob/ob Mice
Authors: Hamrick Mark W , Della-Fera Mary Anne , Choi Yang-Ho , Pennington Catherine , Hartzell Diane , Baile Clifton A 
Published: April 2006

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 &gt;20% (p &lt; 0.05) compared with PBS-treated ob/ob mice. The decrease in adipocyte number with leptin treatment is accompanied by an increase in concentration of the apoptosis marker caspase-3 in bone marrow adipocytes and hematopoietic cells. Both leptin doses also significantly (p &lt; 0.05) increased the percentage of fluorochrome-labeled tibial endosteal surface by &gt;30% compared with PBS-treated ob/ob mice. Leptin treatment increased whole body BMC by &gt;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.
PTHrP Signaling Targets Cyclin D1 and Induces Osteoblastic Cell Growth Arrest
Authors: Datta Nabanita S , Chen Chen , Berry Janice E , McCauley Laurie K 
Published: April 2006

Abstract
PTHrP control of the MC3T3-E1 cell cycle machinery showed that, during differentiation, PTHrP induced G1 growth arrest. Cyclin D1 was a critical mediator as a downstream effector of cAMP, PKC, and MAPK signaling, and the process was PKA-independent. The involvement of JunB has been found critical for PTHrP effects.
Introduction: PTH-related protein (PTHrP) has been implicated in the control of bone cell turnover, but the mechanisms underlying its effect on osteoblast proliferation and differentiation have not been clearly defined. The mechanisms by which PTHrP impacts cell cycle proteins and the role of signaling pathways in differentiated osteoblasts were studied.
Materials and Methods: To elucidate the role of PTHrP, flow cytometric analyses were performed using MC3T3-E1 and primary mouse calvarial cells. Relative protein abundance (Western blot), physical association of partners (immunoprecipitation), and kinase activities (in vitro kinase assays using either GST-Rb or H1-histone as substrates) of cell cycle-associated proteins in vehicle and PTHrP-treated 7-day differentiated cells were determined. ELISA and/or Northern blot analyses were done to evaluate JunB and cyclin D1 expression. SiRNA-mediated gene silencing experiments were performed to silence JunB protein. Finally, inhibitors of cAMP, protein kinase A (PKA), protein kinase C (PKC), and mitogen-activated protein kinase (MAPK) were used to determine involvement of different signaling pathways.
Results: PTHrP inhibited cyclin D1 protein expression 7-fold in a dose- and time-dependent manner and increased the level of p16 protein in differentiated osteoblasts. Additionally, PTHrP reduced cyclin D1-CDK4/CDK6 and CDK1 kinase activities. Forskolin, a cAMP agonist, mimicked PTHrP action, and the PKC inhibitor, GF109203X, slightly blocked downregulation of cyclin D1, implying involvement of both cAMP and PKC. U0126, a MAPK inhibitor, alone decreased cyclin D1 protein, suggesting that the basal cyclin D1 protein is MAPK dependent. H-89, a PKA inhibitor, did not alter the effect of PTHrP on cyclin D1, suggesting a PKA-independent mechanism. Finally, expression of JunB, an activating protein-1 transcription factor, was significantly upregulated, and silencing JunB (siRNA) partially reversed the cyclin D1 response, implying involvement of JunB in the PTHrP-mediated growth arrest of MC3T3-E1 cells.
Conclusion: PTHrP upregulates JunB and reduces cyclin D1 expression while inducing G1 cell cycle arrest in differentiated osteoblasts. Such regulation could be an important determinant of the life span and bone-forming activity of osteoblasts.
Rac1/Cdc42 and RhoA GTPases Antagonistically Regulate Chondrocyte Proliferation, Hypertrophy, and Apoptosis
Authors: Wang Guoyan , Beier Frank 
Published: April 2006

Abstract
The intracellular signaling pathways controlling chondrocyte physiology are largely unknown. Here we show that the small GTPases, Rac1 and Cdc42, accelerate the rate of chondrocyte differentiation and apoptosis, thereby antagonizing the activity of RhoA. These results identify Rac1 and Cdc42 pathways as novel regulators of cartilage development.
Introduction: Proliferation, hypertrophic differentiation, and ultimate apoptosis of chondrocytes regulate endochondral bone growth and development, but the intracellular signaling pathways controlling chondrocyte biology are incompletely understood. In this study, we investigated the role of the small GTPases Rac1 and Cdc42 in chondrocytes.
Materials and Methods: Rac1 and Cdc42 expression during chondrogenic differentiation was assessed by RT-PCR and Western blotting. Effects of Rac1 and Cdc42 on parameters of chondrocyte biology were studied using transient transfections into primary mouse chondrocytes and stable transfections of the chondrogenic cell line ATDC5. Luciferase assays, RT-PCR, cell proliferation, alkaline phosphatases assays, staining procedures, TUNEL assays, and caspase activity assays were performed to study the chondrocyte response to overexpression of Rac1 and Cdc42 proteins. Activation of the p38 pathway was analyzed using Western blotting with phospho-specific antibodies, and mitogen-activated protein (MAP) kinase pathways were inhibited using pharmacological approaches.
Results and Conclusions: Rac1 and Cdc42 activities are required for maximal activity of the collagen X promoter, a hypertrophic marker, in primary chondrocytes, suggesting essential roles of these GTPases in chondrocyte hypertrophy. Overexpression of Rac1 or Cdc42 in chondrogenic ATDC5 cells results in reductions in cell numbers and marked acceleration of hypertrophic differentiation, thus opposing the effects of the related GTPase RhoA. Rac1 and Cdc42 also induce accelerated chondrocyte apoptosis, as shown by TUNEL and caspase activity assays and changes in cell morphology and actin organization. Rac1 and Cdc42 overexpression results in activation of the p38 MAP kinase pathway in ATDC5 cells, and pharmacological inhibition of p38 signaling blocks the effects of Rac1 and Cdc42 overexpression on hypertrophy and apoptosis. Our results therefore suggest that Rac1 and Cdc42 signaling accelerates progression through the chondrocyte life cycle in a p38-dependent fashion and antagonizes RhoA signaling pathways in chondrocyte proliferation, hypertrophy, and apoptosis.
Vitamin D Receptor Fok1 Polymorphisms Affect Calcium Absorption, Kinetics, and Bone Mineralization Rates During Puberty
Authors: Abrams Steven A , Griffin Ian J , Hawthorne Keli M , Chen Zhensheng , Gunn Sheila K , Wilde Margaret , Darlington Gretchen , Shypailo Roman J , Ellis Kenneth J 
Published: April 2006

Abstract
Few studies of the VDR polymorphisms have looked at calcium metabolism or long-term effects. We measured bone mineralization and calcium metabolic parameters longitudinally in a group of 99 adolescents. We found a significant relationship between calcium absorption and skeletal calcium accretion and the Fok1, but not other VDR or related, genetic polymorphisms. It seems that the Fok1 polymorphism directly affects bone mineralization during pubertal growth through an effect on calcium absorption.
Introduction: There are few data regarding the relationship between genetic markers for low bone mass and changes in calcium metabolism in childhood or adolescence. We sought to identify the effects of polymorphisms of the vitamin D receptor (VDR) on calcium and bone mineral metabolism in a longitudinal study of pubertal adolescents.
Materials and Methods: Adolescents (n = 99) received comprehensive stable isotope studies of calcium absorption, bone calcium kinetics, and bone mineralization. Studies were repeated 12 months later. Polymorphisms of putative genetic markers were determined and related to bone mineralization and calcium metabolic finding. Results were analyzed by ANOVA in which changes over time were determined using the initial value as a covariate.
Results: Polymorphisms of the Fok1 gene of the VDR were significantly related to calcium absorption (p = 0.008) and whole body BMC (p = 0.03) and BMD (p = 0.006). The Fok1 effect on whole body BMD was significant for those with Ca intake &gt;800 mg/day (p &lt; 0.001), whereas for those with Ca intake ≤800 mg/day, the Fok1 genotype did not have a significant effect on whole body BMD (p = 0.40). The Fok1 genotype was significantly related to the changes during the year in whole body calcium accretion, with the ff genotype having a 63 ± 20 mg/day deficit compared with the FF genotype (p = 0.008).
Conclusions: The Fok1 polymorphism of the VDR receptor seems to directly affect bone mineral accretion during pubertal growth through an effect on calcium absorption. The relationship between different genetic polymorphisms and bone mineral metabolism may vary by life stage as well as diet.