Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Development”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2003

Bone development and age-related bone loss in male C57BL/6J mice.

The objective of this study was to examine changes in the long bones of male C57BL/6J mice with growth and aging, and to consider the applicability of this animal for use in studying Type II osteoporosis. Male C57BL/6J mice were aged in our colony between 4 and 104 weeks (n=9-15/group). The right femur and humeri were measured for length and subjected to mechanical testing (3-point flexure) and compositional analysis. The left femurs were embedded and thick slices at the mid-diaphysis were assessed for morphology, formation indices, and bone structure. In young mice, rapid growth was marked by substantial increases in bone size, mineral mass, and mechanical properties. Maturity occurred between 12 and 42 weeks of age with the maintenance of bone mass and mechanical properties. From peak levels, mice aged for 104 weeks experienced decreased whole femur mass (12.1 and 18.6% for dry and ash mass, respectively), percentage mineralization (7.4%), diminished whole bone stiffness (29.2%), energy to fracture (51.8%), and decreased cortical thickness (20.1%). Indices of surface-based formation decreased rapidly from the onset of the study. However, the periosteal perimeter and, consequently, the cross-sectional moments of inertia continued to increase through 104 weeks, thus maintaining structural properties. This compensated for cortical thinning and increased brittleness due to decreased mineralization and stiffness. The shape of the mid-diaphysis became increasingly less elliptical in aged mice, and endocortical resorption and evidence of subsequent formation were present in 20-50% of femurs aged > or =78 weeks. This, combined with the appearance of excessive endocortical resorption after 52 weeks, indicated a shift in normal mechanisms regulating bone shape and location, and was suggestive of remodeling. The pattern of bone loss at the femoral mid-diaphysis in this study is markedly similar to that seen in cortical bone in the human femoral neck in Type II osteoporosis. This study has thus demonstrated that the male C57BL/6J mouse is a novel and appropriate model for use in studying endogenous, aging-related osteopenia and may be a useful model for the study of Type II osteoporosis.

Aging↗
PubMed2005

Inducible nitric oxide synthase mediates bone development and P. gingivalis-induced alveolar bone loss.

The role of inducible nitric oxide synthase (iNOS) in bone development and bacterially induced periodontal bone loss was examined using mice with targeted mutation of the iNOS gene. Femurs of iNOS KO mice showed 30% and 9% higher bone mineral density compared to wild type (WT) at 4 and 9 weeks of age, respectively. Micro-computed tomography revealed that cortical thickness and cortical bone density is increased in the absence of iNOS, while trabecular bone thickness and bone density remains unchanged. Histochemical analysis using TRAP staining showed that osteoclast numbers are lower by 25% in iNOS KO femurs compared to WT femurs. When bone marrow cells were stimulated with M-CSF and RANKL in vitro, iNOS KO cultures developed 51% fewer TRAP-positive multinuclear cells compared to WT cultures. When similar cultures were grown on dentine discs, resorption pit area was decreased by 54% in iNOS KO cultures. Gene expression studies showed that iNOS expression is induced by M-CSF and RANKL in WT bone marrow cultures, while no iNOS transcript was detected in iNOS KO. No compensatory change was detected in the expression of neuronal or endothelial NOS isoforms. There was no difference in RANK and osteoprotegerin expression between iNOS KO and WT bone marrow cultures after M-CSF and RANKL-treatment, while Traf6 expression was significantly lower in the absence of iNOS. In the alveolar bone of the maxilla, the distance between the cementoenamel junction and the alveolar bone crest was larger in iNOS KO compared to WT mice from 6 to 14 weeks of age, indicating a developmental effect of iNOS in oral tissues. Oral administration of the periodontal pathogen Porphyromonas gingivalis caused alveolar bone loss in the maxilla of WT mice, but failed to do so in iNOS KO mice. Expression of the osteoclast marker cathepsin K was 25% lower in iNOS KO alveolar bone. These data indicate that iNOS promotes bone resorption during bone development as well as after bacterial infection, and that iNOS is an important signal for normal osteoclast differentiation.

Alveolar Bone Loss↗
PubMed2002

Physical activity and bone development during childhood and adolescence. Implications for the prevention of osteoporosis.

Osteoporotic fractures are a debilitating and a frequently fatal health problem for older adults. A growing body of evidence indicates that osteoporosis has its origin in early life and that the level of development of bone mass during childhood and adolescence strongly influences the risk for osteoporotic fractures. The development of osteoporosis results from an interaction between 1) bone mass accrual via growth, remodeling, and modeling during childhood and adolescence and 2) the maintenance of bone mass (primarily via remodeling) during adulthood. Peak bone mass which occurs at the conclusion of growth may be the most important factor for preventing osteoporosis since as much bone is accrued during the adolescent years as most individuals will lose during all of adult life. In this review, I examine the contribution of physical activity as an important behavioral determinant of children's bone development, particularly of peak bone mass. Since it is a behavior, physical activity is a potentially modifiable determinant of peak bone mass; therefore, understanding activity's impact on bone health is central to developing primary prevention strategies for osteoporosis.

Absorptiometry, Photon↗
PubMed2001

Ossification in the human calcaneus: a model for spatial bone development and ossification.

Perichondral bone, the circumferential grooves of Ranvier and cartilage canals are features of endochondral bone development. Cartilage canals containing connective tissue and blood vessels are found in the epiphysis of long bones and in cartilaginous anlagen of small and irregular bones. The pattern of cartilage canals seems to be integral to bone development and ossification. The canals may be concerned with the nourishment of large masses of cartilage, but neither their role in the formation of ossification centres nor their interaction with the circumferential grooves of Ranvier has been established. The relationships between cartilage canals, perichondral bone and the ossification centre were studied in the calcaneus of 9 to 38-wk-old human fetuses, by use of epoxy resin embedding, three-dimensional computer reconstructions and immunhistochemistry on paraffin sections. We found that cartilage canals are regularly arranged in shells surrounding the ossification centre. Whereas most of the shell canals might be involved in the nourishment of the cartilage, the inner shell is directly connected with the perichondral ossification groove of Ranvier and with large vessels from outside. In this way the inner shell canal imports extracellular matrix, cells and vessels into the cartilage. With the so-called communicating canals it is also connected to the endochondral ossification centre to which it delivers extracellular matrix, cells and vessels. The communicating canals can be considered as inverted 'internal' ossification grooves. They seem to be responsible for both build up intramembranous osteoid and for the direction of growth and thereby for orientation of the ossication centre.

Calcaneus↗
PubMed2003

The influence of nacre surface and its modification on bone apposition: a bone development model in rats.

BACKGROUND: Bone graft substitutes are currently used individually or in various combinations in reconstructing bone defects. Nacre, marine mineralized structure, was recently proposed as a very biocompatible and osteoinductive material for use in periodontal and implant surgery. Our aim was to investigate the interaction between natural nacre and fresh bone marrow, during bone development, in an ectopic site of DA rats. Surface modifications of nacre were tested. METHODS: Demineralized bone matrix (DBM) cylinders (demineralized cortex of diaphysis) prepared from rat femurs were filled with fresh marrow, which was removed from other 2-month old DA rat femurs. Natural nacre particle or nacre which was treated with HCl, phosphate buffer saline (PBS), and Ca(OH)2 to modify its surface was placed into the DBM cylinders. The cylinders were implanted subcutaneously at the thoracic region of growing DA rats. After 4 weeks the cylinders were surgically removed, fixed in buffered formalin, and x-rayed. Scans of the microradiographs and histological evaluation of the DBM cylinders including bone developed at the interface of nacre and its surface modifications were compared to marrow controls. RESULTS: The results show that natural nacre is a poor conductive biomaterial in a bone developmental environment. Nacre surface treated with Ca(OH)2 and PBS was found to be most biocompatible. In this group, new bone was apposed directly on the nacre surface and the total amount of bone was highest in comparison to other treatment groups. CONCLUSIONS: This study does not support previous observations that nacre is osseoinductive. Our model system seems to be very sensitive and capable of testing interaction between surface modifications of biomaterials and fresh marrow in the process of new bone development.

Analysis of Variance↗
PubMed2006

Intracortical remodeling during human bone development--a histomorphometric study.

Although intracortical bone remodeling is a key aspect of bone physiology, very little is known about this process during human bone development. In this study, we examined transiliac bone samples from 56 individuals between 1.5 and 22.9 years of age (31 female; tetracycline labeling present in 42 subjects) who did not have evidence of metabolic bone disease. Parameters of osteonal structure (osteon diameter, wall thickness, diameter of osteonal canals) and dynamic measures of intracortical remodeling were determined separately for the external and internal cortex. We found that measures of osteonal structure were independent of age. However, the percentage of osteons showing metabolic activity was lower in the older study subjects, corresponding to a slowdown in the turnover of cortical bone. Most dynamic parameters of bone metabolism were higher in the internal cortex than in the external cortex. Cortical porosity was negatively associated with age on the external, but not on the internal cortex. The bone forming activity that refills the remodeling cavities seemed to favor the side of the osteonal canal that faced towards the periosteum. In summary, intracortical remodeling activity varies markedly during bone development, and is slightly asymmetric between the two cortices of an iliac bone specimen. Remodeling during development is thus an age-dependent process that varies with location even within the same bone.

Adolescent↗
PubMed2006

[PTHrP and bone sialoprotein as prognostic markers for developing bone metastases in breast cancer patients].

BACKGROUND: Bone metastases belong to the most frequent metastases in breast cancer. Currently there exist no serum markers which allow early detection of bone metastases. PATIENTS AND METHODS: 89 patients with primary breast cancer have been investigated for parathyroid-hormone-related peptide (PTHrP) in the tumour and bone sialoprotein (BSP) in the serum. Both markers have been correlated with classical prognostic factors and survival. RESULTS: The median age of the patients was 56 years. 17 of the 89 patients developed bone metastases and 25 died during the observation period of 5 years. PTHrP correlated significantly with bone metastases free survival (p = 0.0004) and overall survival (p = 0.0005), whereas BSP correlated only with the bone metastases free survival (p = 0.03). Both markers were shown to be independent prognostic factors for the bone metastases free survival in the multivariate analysis. PTHrP was also found to be an independent prognostic factor for the overall survival. CONCLUSION: The investigation of PTHrP could be a prognostic marker for the presence of bone metastases while BSP could be a marker for the early detection of bone metastases.

Biomarkers, Tumor↗
PubMed2003

The regulation of bone development as a biological system.

A large number of molecular, cellular, and epidemiologic factors have been implicated in the regulation of bone development. A major unsolved problem is how to integrate these disparate findings into a concept that explains the development of bone as an organ. Often, events at the organ level are simply presented as the cumulative effect of all factors that individually are known to influence bone development. In such a cumulative model it must be assumed that each bone cell carries the construction plan of the entire skeletal anatomy in its genes. This scenario is implausible, because it would require an astronomical amount of positional information. We therefore propose a functional model of bone development, which is based on Frost's mechanostat theory. In this model, the genome only provides positional information for the basic outline of the skeleton as a cartilaginous template. Thereafter, bone cell action is coordinated by the mechanical requirements of the bone.

Animals↗
PubMed2005

Skeletal development, bone remodeling, and hematopoiesis.

In adult mammals, the bone marrow microenvironment is defined by close interactions between cells derived from mesenchymal progenitors and cells derived from hematopoietic progenitors. The influence that one population of cells has over the other has been a matter of intense study since it was established that hematopoietic stem cells (HSCs) require support of stromal elements to engraft, self-renew, and progress towards lineage commitment. Within the stromal components, cells of the osteoblastic lineage have the ability to interact with HSCs, and it has been proposed that they could be one of the main cell types responsible for the generation and maintenance of hematopoietic niches. Possible molecular mechanisms involved in the interaction between osteoblastic and hematopoietic cells have been described. However, understanding the relative importance of each one of them, their production by defined cells, and their kinetics of appearance have been limited by the lack of in vivo models allowing the physical and/or temporal dissection of the components of the osteoblastic lineage. Here, we provide a summary of the evidence that have established the importance of osteoblasts in hematopoiesis, and we propose new experimental strategies that could help to define the nature of these interactions.

Animals↗
PubMed1994

Effects of floor versus cage rearing and feeder space on growth, long bone development, and duration of tonic immobility in single comb White Leghorn pullets.

The effects of feeder space on growth of commercial layer pullets reared in cages or floor pens were examined by allocating 1-d-old chicks to either cages (14 chicks) or floor (119 chicks). Feeder spaces were 5.4, 4.0, and 2.7 cm per pullet and were held constant throughout the growing period, resulting in a 2 x 3 factorial arrangement. Measurements of pullet body weight, feed consumption, skeletal development, and fearfulness were taken through the rearing period to 18 wk. Pullets allowed 5.4 cm of feeder space were heavier (P < .001) (1,329 g at 18 wk of age) than birds allowed either 4.0 or 2.7 cm of feeder space (1,289 and 1,272 g, respectively). Floor-reared pullets weighed significantly more at 12, 16, and 18 wk of age than cage-reared pullets. Feed consumption was not affected by the feeder space, but the floor-reared birds consumed more (P < .001) feed than those in cages (61.2 vs 52.8 g per pullet per d). Mortality, skeletal development, and bone strength were not affected by either feeder space or floor vs cage rearing. Floor-reared pullets had longer (P < .05) duration of tonic immobility (TI) than those reared in cages (519.7 and 471.4 s, respectively, as measured at 18 wk). Feeder space per pullet had no effect on the duration of TI of the pullets. Cage and floor rearing environments are comparable for rearing pullets provided feeder space is not restricted to such an extent as to inhibit BW.

Animal Husbandry↗