Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Remodeling”

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 289 records · Page 16Linked to original sources
PubMedDate not supplied

Quantum type bone remodeling in the otic capsule of the pig.

Normal quantum type bone remodeling was studied in temporal bones of young domestic pigs by means of combined microradiography, osteofluorochrome labelling and osteoid staining. Evolving secondary osteons were morphologically normal although much less in the otic capsule than in the surrounding compacta of the temporal bones or in long bones. Moreover, remodeling was totally absent in bone tissue immediately adjacent to perilymphatic spaces suggesting the presence of a local mechanism controlling resorption and perhaps formation in the bony otic capsule.

Animals↗
PubMed2005

[Molecular mechanism of tissue-specific actions of sex steroid hormones and SERM for bone remodeling].

Female sex steroid hormone, estrogen, exerts a wide variety of biological actions including lipid metabolism and bone remodeling. Moreover, estrogen is known to be involved in many pathological states like osteoporosis, tumor incidence and tumor development of female reproductive organs. Most of such estrogen actions are believed to mediate transcriptional controls of a particular set of target genes by its nuclear receptor, estrogen receptor (ER). The products of the genes regulated by ER are responsible for the overt estrogen actions in the many estrogen target tissues. Reflecting the estrogen actions, two ER subtypes (alpha, beta) express in the bone and the other target tissues. ER is a hormone-dependent transcriptional factor and hormone binding is known to alter the structure of ER protein, following dissociation/recruitment of multiple co-regulator complexes. Synthetic ER ligands, SERM, are believed to cause the ligand type-specific alteration in ER structure. This SERM-induced structural alteration acquires the tissue-specific function of liganded ER, as SERM acts as an agonist for bone remodeling.

Bone Remodeling↗
PubMed1998

[Normal bone remodelling--what can go wrong in osteoporosis?].

The skeleton is a metabolically active organ in constant change and renewal. Specialised cells are responsible for resorbing and synthetizing bone matrix. The process of bone remodelling, by removing old and damaged bone tissue and replacing it with new, is necessary for conserving the integrity of bone. In recent years, research has given new insight into the fine relationship between different cell types in bone tissue. This has enhanced our understanding of the pathophysiology behind osteoporosis and other metabolical bone diseases. This article gives a summary of our present knowledge of the normal cell biology of bone and what contributes to its regulation. How this helps the understanding of normal and pathological bone loss is illustrated. It is important to understand bone remodelling in order to interpret measurements of bone mineral density and biochemical markers accurately.

Aged↗
PubMed1995

Confocal laser scanning microscopic studies on alveolar bone remodeling with orthodontic tooth movement and retention.

Alveolar bone reconstruction in growing dog during the retention period following orthodontic tooth movement was studied. Three beagle dogs (8-10 kg body weight, about one-year-old) were used and two of the animals were subjected to histological observation. The upper 2nd and lower 3rd premolars on both sides were extracted prior to the orthodontic treatments. After a healing period of one month, the upper 3rd premolar and the lower 4th premolar on the right side were moved mesially with a conventional orthodontic force for 8 weeks, and then retained in their new position for 4 weeks. The contralateral corresponding premolars were used as control. The alveolar bone was double-labeled with tetracycline (TC) during the movement and calcein (Cal) during the retention period. Alveolar bone structure and labeling patterns were examined by contact microradiography, conventional fluorescence microscopy, and confocal laser scanning microscopy (CLSM). Optimizing the separation of TC and Cal labelings in the alveolar bone was attained by the simultaneous use of ultraviolet (364 nm) and argon (488 nm) laser sources for excitation of TC and Cal, respectively. Cal labeling, indicative of new bone deposition showed two distinct patterns: lamination at the periodontal surface and rings circumscribing the vascular canal. The cementum surface also exhibited active deposition during the experimental period. Bone formation was affected by slight changes in magnitude and direction of orthodontic or occlusal forces. CLSM is valuable in deciphering the process of alveolar bone remodeling.

Alveolar Process↗
PubMed1989

The effect of stress concentration on bone remodeling: theoretical predictions.

Theoretical predictions of internal bone remodeling around an elliptical hole are studied. The internal remodeling theory due to Cowin and Hegedus is employed. The bone is modeled as an initially homogeneous adaptive elastic plate with an elliptical hole under a superposed steady compressive load. It is shown that there will exist a final inhomogeneous remodeling distribution around the hole that will disappear away from the hole. The remodeling is such that the compressive stress concentration causes the bone structure to evolve to one of greater density and stiffer elastic coefficients. The speed of remodeling around the hole and its variation with respect to distance is investigated and discussed. It is shown that the rate of bone reinforcement in the area of compressive stress concentration is much higher than the rate of bone resorption in the area of existing tensile stress. Special cases of a circular hole and vertical and horizontal slots are studied and discussed.

Biomechanical Phenomena↗
PubMed1985

Stress analysis of compression plate fixation and its effects on long bone remodeling.

A three-dimensional finite element model is generated for an intact plexiglass tube with an attached six-hole stainless steel compression plate. The results for a wide range of loads, including cyclic external loads and static tensile preloads in the plate and screws, are examined as specifically related to plate-induced osteopenia. The model demonstrates that disuse osteopenia, resulting from a reduction in magnitude of cyclic axial stress, should be limited to the central region between the inner screws. Also, the addition of a static preload negates any reduced axial stress levels in this region, thus raising questions on the relative importance of static and cyclic stresses for the internal remodeling of bone.

Animals↗
PubMed1992

Abnormal bone remodelling in patients with myelomatosis and normal biochemical indices of bone resorption.

We studied bone biopsies from 26 patients with myelomatosis with apparently normal skeletal metabolism. Quantitative histomorphometric measurements suggested that skeletal disease was progressive despite normocalcaemia and normal urinary excretion rates of calcium and hydroxyproline. When biopsies were divided according to the involvement of marrow by plasma cells, bone resorption--as judged by the eroded surface--increased significantly the greater plasma cell burden. Osteoclasts were frequent with moderate tumour burdens, but there was no further increase in the number of osteoclasts when plasma cell infiltration increased by more than 50% of bone marrow. Contrary to expectation, the numbers of osteoblasts and bone formation rates were increased with bone biopsies with moderate tumour burden, but were markedly lower when plasma cell infiltration occupied more than 50% of bone marrow, due to a decreased functional capacity of osteoblasts. We conclude that skeletal bone disease in myeloma is commonly progressive despite apparently stable bone disease as judged by biochemical measurements. The major mechanism of bone loss in myelomatosis is increased osteoclastic resorption but decreased bone formation contributes to bone loss with heavy plasma cell burdens. Urinary excretion of calcium and hydroxyproline provide insensitive indices of bone resorption in myelomatosis.

Alkaline Phosphatase↗
PubMed2005

A quantitative and qualitative analysis of bone remodelling around custom uncemented femoral stems: a five-year DEXA follow-up.

BACKGROUND: After total hip replacement bone remodelling is determinant for the implant survival. This study asked whether the immediate postoperative amount and distribution of bone can predict the changes in bone amount and distribution after five years in the case of younger patients with custom uncemented implant. METHODS: We investigated 17 hips with a mean follow-up of 5.1 years. The average patient age at follow-up was 48.5 years. We used immediate postoperative and five-year dual energy X-ray absorptiometry measurements of bone mineral content, density, and projected bone area in seven local zones forming a partition of the upper femur. A correlation was sought between the preoperative variables and the five-year variation. Qualitative bone remodelling was analysed considering each local zone in a density-area plane. Based on geometrical considerations, we introduced an index of structural remodelling, which expresses the preponderance of internal remodelling against external modelling. FINDINGS: The bone mineral content at operation correlated significantly with its relative decrease locally laterally mid-proximally and medially (P<0.01), distally, and globally for the femur (P<0.05). For the bone mineral density, the correlation was significant distally, medially and globally (P<0.05). The bone projected area shows only significant correlation laterally mid-proximally (P<0.01). The index of structural remodelling was significantly positive (P<0.01) in all local zones and was independent of the initial bone amount and structure (P>0.1). INTERPRETATION: High bone mineral content at operation correlates significantly with periprosthetic bone loss after five years in younger patients with cementless custom femoral implant. Independently of the net bone mineral content balance, external modelling is stronger than internal remodelling in all local zones.

Absorptiometry, Photon↗
PubMed2005

The effects of suppressed bone remodeling by bisphosphonates on microdamage accumulation and degree of mineralization in the cortical bone of dog rib.

We evaluated the effects of suppressed bone remodeling caused by bisphosphonate on microdamage accumulation and degree of mineralization of bone (DMB) for the dog rib in two independent studies. Study 1: 36 female beagles, 1-2 years old, were treated daily for 1 year with saline vehicle, risedronate at 0.5 mg/kg/day, or alendronate at 1.0 mg/kg/day. Study 2: 29 beagles, 1 year old, were given lactose, or incadronate at 0.3 mg/kg/day or 0.6 mg/kg/day for 3 years. In both studies, the ninth rib was harvested. Intracortical remodeling was significantly suppressed following either 1 year or 3 years of bisphosphonate treatment without impairment of primary mineralization, although the remodeling rate was obviously lower in study 2 than in study 1 because of the aging of animals. Microdamage accumulation was significantly increased following any bisphosphonate treatment in response to the extent of remodeling suppression. One-year treatment with risedronate or alendronate did not significantly affect the mean DMB or osteonal distribution based on DMB. In contrast, mean DMB was significantly increased following 3 years of incadronate treatments, and osteonal distributions based on DMB showed a dose-dependent shift toward the higher values in incadronate-treated animals when compared with controls. Our results demonstrated that DMB was increased following only 3 years but not 1 year of bisphosphonate treatment. This finding suggests that suppressed remodeling induced by long-term bisphosphonate treatment increased DMB by increasing the population of old, highly mineralized osteons; however, the expression of this phenomenon depends on duration of the treatment because the secondary mineralization is a very slow process.

Animals↗
PubMed1995

Human osteoclasts, not osteoblasts, deposit osteopontin onto resorption surfaces: an in vitro and ex vivo study of remodeling bone.

Osteopontin is a phosphorylated glycoprotein believed to be secreted by osteoblasts and deposited into the bone matrix to facilitate osteoclasts adhesion or to initiate osteoid mineralization. Previously we have presented contradictory evidence that osteoclasts express osteopontin mRNA in human remodeling bone. The aim of this study was to ascertain whether osteoclasts synthesize and deposit osteopontin in resorption lucunae. We characterized expression of osteopontin mRNA and protein expression in both intramembranous and endochondral ossification, as well as remodeling bone, in the human osteophyte. Osteopontin mRNA was expressed in osteoclast with tartrate-resistant acid phosphatase (TRAP) positivity within resorption lacunae. The osteoclasts and immediate resorption surfaces also expressed osteopontin. However, osteopontin mRNA and protein were weak (transient) or undetectable in osteoblasts at adjacent bone formation sites; no osteopontin expression was observed in the osteoid, although occasional reactivity was observed in osteocytes and the mineral-osteoid interface. In contrast, osteopontin was highly expressed in the osteoblasts and matrix of woven bone during intramembranous and endochondral ossification. The matrix expression correlated with mineralization; however, in some instances osteopontin deposition was observed prior to mineralization. Similarly, osteopontin expression was evident in cartilage matrix, solely at foci of mineralization. Chondroclasts expressed osteopontin mRNA and protein: the surfaces of resorbed calcified cartilage also expressed osteopontin. Abnormal, unmineralized matrices apparently lacked deposited osteopontin, but were nevertheless resorbed by osteoclasts; the osteoclasts and resorbed surfaces expressed no osteopontin protein. That osteoclasts are responsible for the deposition of osteopontin was confirmed in vitro, whereby resorption pits in whale dentine and bovine bone slices, produced by isolated human osteoclasts, contained deposited osteopontin. Osteopontin may facilitate the adhesion (or detachment) of the osteoclast to the bone surface. Alternatively, the possibility that osteopontin may act as a postresorptive signal to recruit osteoblasts, or to polarize and direct the mineralization of the formed osteoid, is discussed.

Acid Phosphatase↗
PubMed1995

Gastrointestinal calcium absorption and dietary calcium load: relationships with bone remodelling in vertebral osteoporosis.

Patients with vertebral osteoporosis have a wide range of bone loss rates, bone remodelling rates and capacities for gastrointestinal (GI) calcium absorption. To test the hypothesis that variations in GI absorptive capacity determine rates of bone loss or remodelling, we have sought relationships between calcium absorption or vitamin D metabolite levels on the one hand and rates of cancellous and cortical bone loss (measured by serial quantitative computed tomography in the radius; n = 25) or indices of bone remodelling in tetracycline-prelabelled transiliac biopsies (n = 41) on the other, in a sequential untreated group. Calcium absorption (net and true) was measured in 18-day balances and by a two-isotope deconvolution method (fractional absorption and maximum absorption rate, MAR). There was no significant seasonal effect on any of these four measures of calcium absorption (variance ratio, F = 0.52-1.61, p > 0.1) or on 1,25-dihydroxyvitamin D levels (F = 0.13, p > 0.1; range 11-69 pg/ml), notwithstanding the expected seasonal effect on 25-hydroxyvitamin D levels (mean 18.7 ng/ml, zenith mid July, semi-amplitude 7.5 ng/ml; F = 6.82, p < 0.01). Neither this metabolite nor 1,25-dihydroxyvitamin D correlated with any index of calcium absorption (p > 0.1). No measure of calcium absorption (or intake) had a significant relationship with radial cortical or cancellous bone loss (p all > 0.1) but cancellous bone loss was associated with the rate of endogenous calcium excretion (r = 0.50, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1993

Computer simulations of stress-related bone remodeling around noncemented acetabular components.

The authors have used computer modeling techniques to examine stress-related bone changes in the acetabular region. Using a previously developed theory for bone development and adaptation, the authors simulated the distribution of bone density in the natural pelvis as well as changes in bone density following total hip arthroplasty. The geometry of the finite element model was based on a two-dimensional slice through the pelvis. Starting from a solid, homogeneous structure, the computer simulations predicted the distribution of bone density throughout the natural pelvis. The predicted bone density distribution in this first simulation agreed well with the actual bone density distribution only when loads representing multiple activities were incorporated. Using the predicted density distribution as a starting point the authors modified the finite element models to study two designs of noncemented, metal-backed acetabular cups. The simulations with fully fixed bone-implant interfaces predicted extensive loss of bone density medial and inferior to the prosthetic components. The simulations with loose interfaces led to more moderate losses of bone density, indicating a load transfer more similar to that which occurs in the natural joint. The differences in simulated bone remodeling between the two component designs were quite minimal. These results indicate that acetabular components with full bony ingrowth may induce significant stress-related bone remodeling due to a nonphysiologic transfer of load.

Bone Density↗
PubMed1987

Bone remodeling of diaphyseal surfaces by torsional loads: theoretical predictions.

A theory of surface bone remodeling is extended to include the effects of shearing strains as well as normal strains. It is shown that the surface velocity can only depend upon the square of shearing strains, but that it can be linear as well as quadratic in the normal strains. The theory is applied to predict the surface bone remodeling in the diaphysis of a long bone under combined axial and torsional loading. In the general case the diaphysis of the long bone is modeled as a hollow thin-walled cylinder of arbitrary cross-section and, in a special case, as a right circular thin-walled tube. It is shown here that if a thin-walled right circular cylinder capable of surface remodeling is subjected to an axial compressive load and a twisting torque, then the effect of increasing the torque is the same as the effect of decreasing the axial compressive load, namely the mean radius of the cross-section increases and the wall width thins. Conversely, the effect of reducing the torque is the same as the effect of increasing the axial compressive load, namely the mean radius of the cross-section decreases and the wall width thickens.

Animals↗
PubMed1999

Decreased bone formative and enhanced resorptive markers in human immunodeficiency virus infection: indication of normalization of the bone-remodeling process during highly active antiretroviral therapy.

As cytokines and 1,25-dihydroxyvitamin D [1,25-(OH)2D] appear to have an important role in bone homeostasis, we examined the possibility that human immunodeficiency virus (HIV)-infected patients, characterized by enhanced levels of proinflammatory cytokines and 1,25-(OH)2D deficiency, have disturbed bone metabolism by analyzing serum markers of bone formation (osteocalcin) and bone resorption (C-telopeptide) in 73 HIV-infected patients. HIV-infected patients with advanced clinical and immunological disease and high viral load were characterized by increased C-telopeptide and particularly by markedly depressed osteocalcin levels. HIV-infected patients had enhanced activation of the TNF system. Serum concentrations of p55 and p75-TNF receptors were negatively correlated with osteocalcin, and p75-TNF receptor was positively correlated with C-telopeptide. HIV-infected patients with advanced disease also had decreased serum concentrations of 1,25-(OH)2D, but this parameter was not correlated with osteocalcin or C-telopeptide. During 24 months with highly active antiretroviral therapy there was a marked rise in serum osteolcalcin levels together with a profound fall in viral load and TNF components and a marked rise in CD4+ T cell counts. Also, there was a shift from no correlation to a significant correlation between osteocalcin and C-telopeptide levels during such therapy. The present study suggests disturbed bone formation and resorption during HIV infection. Our findings indicating synchronization of bone remodeling during highly active antiretroviral therapy may represent a previously unrecognized beneficial effect of such therapy and expand our knowledge of the interactions between cytokines and bone in the bone-remodeling process.

Adult↗
PubMed2000

Theoretical solutions for internal bone remodeling of diaphyseal shafts using adaptive elasticity theory.

In this paper we considered the problem of internal bone remodeling induced by casting a broken femur. It is shown that, after the removal of the plastercast, the healing bone is either becoming more porous and less stiff or it is osteoporotic. The result is theoretical, based on a theory of internal bone remodeling proposed by Hegedus and Cowin (Journal of Elasticity 6, 1976, 337-352).

Adaptation, Physiological↗
PubMed1984

Vitamin D levels and trabecular bone remodelling before and after surgery for medullary thyroid carcinoma.

We previously reported increased mean serum 1,25-dihydroxyvitamin D (1,25-(OH)2D) and increased trabecular bone remodelling in patients with medullary thyroid carcinoma (MCT) and hypercalcitoninaemia. In the present paper we report that serum 1,25-(OH)2D and trabecular bone remodelling decreased following surgical cure for MCT and hypercalcitoninaemia in 4 patients despite no detectable post-surgical hypoparathyroidism or hypothyroidism. The results obtained in the present small number of patients suggest that the altered vitamin D metabolism and trabecular bone remodelling in patients with MCT is caused by the hypercalcitoninaemia.

24,25-Dihydroxyvitamin D 3↗