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PubMed2005

[Reparative bone regeneration after aseptic necrosis of the femoral head as influenced by 1-chloromethylsilatrane treatment].

The aim of this work was to study the effect of 1-chloromethyisilatranum on the processes of reparative bone regeneration in experimentally induced aseptic femoral head necrosis. Aseptic femoral head necrosis was modeled in 4 Chinchilla rabbits by destruction of spongy substance of femoral neck and cutting of ligamentum teres of its head. Rabbits of the experimental group were injected with 0.4 ml of 1% solution of 1-chloromethylsilatranum on postoperational days 5, 10, 15 and 20 into the damaged femoral head and close to the damaged joint. Animal were sacrificed by air embolism 5 weeks from the start of an experiment. Necrotic and repair processes in hip joints from damaged and intact sides were assessed radiologically and histologically prior to sacrifice. In rabbits of both control and experimental groups extensive aseptic necrosis of hip joints was found. The osseous tissue of damaged hip joints of experimental animals contained the chains of osteoblasts actively producing new bone matrix. Foci of bone regeneration were found both in the deep and peripheral regions of the epiphysis, which is indicative of active processes of bone repair. The results obtained suggest that administration of organic-silicon drug 1-chloromethylsilatranum stimulates (optimizes) the processes of repair osteogenesis following aseptic femoral head necrosis in experimental animals. Application of this preparation appears to be very promising.

Animals↗
PubMed1991

Radiation absorbed dose calculations for samarium-153-EDTMP localized in bone.

Calculations have been undertaken to estimate the likely radiation dose received by patients undergoing treatment with samarium-153-EDTMP. Previously known bone structure parameters have been employed to partition correctly the energy absorbed in the bone matrix between red bone marrow, yellow marrow, and various types of mineral bone. Both uniform surface and volume distribution of the radioactivity are considered. The key findings of the calculations can be stated in terms of the MIRD "S-factors" for red bone marrow and the endosteal layer of cells on bone surfaces. In particular, the S-factor for red bone marrow is either 0.0276 mGy/MBq.h or 0.0077 mGy/MBq.h for surface and volume distributed radioactivity, respectively. For the endosteal layer of thickness (10 microns) on bone surfaces, the corresponding values are 0.0723 mGy/MBq.h and 0.0213 mGy/MBq.h, respectively.

Beta Particles↗
PubMed1986

Experimental aluminum-induced bone disease: studies in vivo.

The administration of aluminum to experimental animals can induce osteomalacia in previously normal bone. Aluminum exposure impairs the synthesis of new bone matrix which reduces bone formation. A specific action of aluminum to inhibit the mineralization of bone in vivo has not yet been demonstrated. The role of parathyroid hormone in the pathogenesis of the osteomalacia that develops after aluminum loading also remains uncertain. However, the occurrence of both osteomalacia and impaired bone formation in experimental animals following aluminum administration has been documented in the absence of reductions in the serum levels of PTH. The results of the animal studies completed to date are consistent with a direct adverse effect of aluminum to suppress new bone formation. This response of bone may be mediated through a toxic effect of aluminum on the osteoblast. Whether aluminum also disrupts the mineralization of bone by a mechanism separate from its effect on the osteoblast requires additional study.

Aluminum↗
PubMed1974

Effects of parathyroid hormone on bone of thyroparathyroidectomized rats: an ultrastructural and enzymatic study.

Osteoblasts and osteocytes in adult thyroparathyroidectomized (T(x)PT(x)) rats fed a low calcium vitamin D-free diet and given parathyroid (PTH) had ultrastructural evidence of increased activity compared to controls. Osteoblasts in PTH-treated rats had prominent rough endoplasmic reticulum and Golgi apparatuses and large mitochondria. The plasma membranes were extensively convoluted and associated with initial loci of mineralization in osteoid. Osteocytes contained increased rough endoplasmic reticulum, well-developed Golgi apparatuses and large mitochondria. Lacunar walls were roughened, but osteocytic osteolysis was not observed. Osteoclasts were encountered more frequently in PTH-treated rats, but their ultrastructural features were similar to those of controls. Osteoblasts and osteocytes in controls appeared to be inactive cells lining quiescent mineral surfaces. Parathyroid hormone treatment increased serum calcium levels and urinary hydroxyproline excretion, indicating enhanced resorption of bone mineral and matrix. Bone alkaline phosphatase and calcium-adenosine triphosphatase activities were elevated after PTH treatment and may be related to increased calcium transport by bone cells. These findings were interpreted to suggest that PTH mobilizes bone mineral by osteoclasis and increases metabolic activity of the osteocyte-osteoblast pump.

Adenosine Triphosphatases↗
PubMed1994

The healing of grafts combining freeze-dried and demineralized allogeneic bone in rabbits.

The adjunctive role of demineralized bone matrix (DBM) in enhancing the incorporation of segmental freeze dried (FD)-allogeneic bone grafts has been studied in the rabbit ulna and fibula. The studies compared the healing patterns of fresh segmental autografts, FD-allografts, DBM-allografts, and FD-allografts supplemented at the graft-host junctions with FD- or DBM-allografts as particulates (ulna) or as segmental struts (fibula). The outcome was evaluated at five and ten weeks by a radiologic score, by biomechanical properties (breaking strength, energy to failure, stiffness), and histology. The ulnar autografts healed most rapidly (ten weeks = 100%), followed by DBM allografts (60%). By all criteria, FD-allografts were poorly incorporated (20-40%), and the process was not improved by supplements of FD- or DBM-particulate/strut bone. Histologically, the DBM component of composite fibular strut grafts was osteoinductive and united with host tissues within 35 days. The contiguous FD-allograft struts were not incorporated, showing fibrocartilaginous nonunions and resorptive foci. While the addition of DBM does not protect FD-allograft integrity in the rabbit, segmental mineralized FD-allografts could provide mechanical support for some intervals until, in such composite grafts, osteoinductive processes produced biomechanically competent new bone.

Animals↗
PubMed1996

Biochemical properties of cortical allograft bone using a new method of bone strength measurement. A comparison of fresh, fresh-frozen and irradiated bone.

There have been conflicting reports on the effects of gamma irradiation on the material properties of cortical allograft bone. To investigate changes which result from the method of preparation, test samples must be produced with similar mechanical properties to minimise variations other than those resulting from treatment. We describe a new method for the comparative measurement of bone strength using standard bone samples. We used 233 samples from six cadavers to study the effects of irradiation at a standard dose (28 kGy) alone and combined with deep freezing. We also investigated the effects of varying the dose from 6.8 to 60 kGy (n = 132). None of the treatments had any effect on the elastic behaviour of the samples, but there was a reduction in strength to 64% of control values (p < 0.01) after irradiation with 28 kGy. There was also a dose-dependent reduction in strength and in the ability of the samples to absorb work before failure. We suggest that irradiation may cause an alteration in the bone matrix of allograft bone, but provided it is used in situations in which loading is within its elastic region, then failure should not occur.

Adolescent↗
PubMed1993

Transforming growth factor-beta accelerates osteoinduction in a craniofacial onlay model.

Recombinant human transforming growth factor beta 1 was added to a demineralized bone matrix (DBM) paste, formed into cylinders and implanted onto the cranial periosteum of New Zealand White rabbits. The TGF-beta was added at doses of 0, 0.3, 3, 30 and 75 micrograms per implant. When the implants were removed after six weeks, histomorphometric analysis of the implants showed that TGF-beta induced significantly higher levels of trabecular bone formation than in the controls (mineralized bone area 6.0 +/- 0.8, 6.0 +/- 1.2, 5.6 +/- 1.0, 10.1 +/- 1.5, and 10.8 +/- 1.4 mm2, respectively, P < 0.05), TGF-beta also caused greater resorption of the demineralized bone matrix carrier (matrix area 7.2 +/- 0.9, 6.8 +/- 1.4, 3.7 +/- 0.9, 2.7 +/- 1.2, 0.9 +/- 0.5 mm2, respectively, P < 0.02). Measurements of the osteoid demonstrated a more active bone surface and there was evidence of rapid bone remodeling. Similar results were obtained using TGF-5 beta, a new hybrid molecule. These results demonstrate the capacity of transforming growth factor beta in accelerating osteoinduction.

Analysis of Variance↗
PubMed1994

Estimation of age at death based on aspartic acid racemization in noncollagenous bone proteins.

Age at death determination based on the extent of aspartic acid racemization in dentin has been reported to be highly accurate and reproducible. To test the applicability of this method to human bone, aspartic acid racemization in noncollagenous proteins of bone was investigated. A close relationship was found between age at death and the extent of aspartic acid racemization in osteocalcin, the most abundant noncollagenous protein of the organic bone matrix. Our findings indicate that osteocalcin is a permanent, 'aging' constituent of the organic bone matrix whose D-aspartic acid content increases with age because of in vivo racemization. Thus, the extent of aspartic acid racemization in bone osteocalcin is a measure of the age of the peptide and hence of the entire organism. The relationship between age at death and the extent of aspartic acid racemization in purified bone osteocalcin appears to be close enough to serve as a basis for determination of age at death in forensic medicine.

Age Determination by Skeleton↗
PubMed1993

Biochemical markers of bone turnover. I: Theoretical considerations and clinical use in osteoporosis.

The recent development of noninvasive techniques to measure bone mass and bone turnover represents a major advance in the diagnosis and management of osteoporosis. The rate of formation or degradation of the bone matrix can be assessed either by measuring a prominent enzymatic activity of the bone-forming or resorbing cells, such as alkaline and acid phosphatase activity, or by measuring bone matrix components released into the circulation during formation or resorption. Recent studies have shown that the appropriate combination of the most efficient markers of bone resorption and formation will provide a powerful tool in the clinical investigation of osteoporosis.

Alkaline Phosphatase↗
PubMed1997

Bone biology.

Bone is a metabolically active and highly organized tissue consisting of a mineral phase of hydroxyapatite and amorphous calcium phosphate crystals deposited in an organic matrix. Bone has two main functions. It forms a rigid skeleton and has a central role in calcium and phosphate homeostasis. Bone modelling is the process associated with growth and re-shaping of bones in childhood and adolescence. This is distinguished from bone remodelling, which describes the lifelong process whereby skeletal tissue is continually being resorbed and replaced in order to maintain skeletal integrity, shape and mass. Bone remodelling is controlled by systemic hormones and cytokines and is an integral part of the calcium homeostatic system. The maintenance of a normal, healthy skeletal mass depends on interactions between osteoblasts, osteoclasts and constituents of the bone matrix to keep the process of bone resorption and formation in balance. The factors, local and systemic, which regulate these processes are discussed.

Animals↗
PubMed2000

Immunohistochemical localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias in rats.

Type I collagen, fibronectin and tenascin C play an important role in regulating early osteoblast differentiation, but the temporal and spatial relationship of their localization during embryonic osteogenesis in vivo is notknown. The present study was designed to localize these three molecules in the dentary of mandibles and tibias in rat embryos using immunohistochemistry. Serial paraffin sections were cut and adjacent sections were processed for von Kossa staining or immunohistochemistry for type I collagen, fibronectin and tenascin C. In the dentary, tenascin C was localized within and around the mesenchymal cell condensation in embryos at 14 days in utero. The bone matrix at 15 days showed immunoreactivity for both type I collagen and fibronectin. The immunoreactivity of type I collagen was persistent, whereas that of fibronectin decreased with age of embryos. In tibias, tenascin C was localized in the perichondral mesenchymal tissue at 17 days. Immunoreactivity for type I collagen was persistent in the bone matrix, whereas the tibial bone showed little immunoreactivity for fibronectin at any embryonic age examined. The present study demonstrated characteristic localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias.

Animals↗
PubMed2002

Bone regeneration of localized chronic alveolar defects utilizing cell binding peptide associated with anorganic bovine-derived bone mineral: a clinical and histological study.

BACKGROUND: Osteoinduction to treat osseous defects has been attempted by several means. Some clinical studies have demonstrated that a synthetic cell binding peptide (P-15) with anorganic bovine derived bone matrix (ABM) has the ability to enhance bone regeneration. These studies suggest that more histological data are necessary to better understand this process. We have developed a Class III chronic alveolar defect animal model to investigate space-maintaining regenerative materials. The objective of this study was to clinically and histologically evaluate the use of P-15/ABM with or without a bioabsorbable membrane (M) to regenerate localized chronic alveolar ridge defects in dogs. METHODS: Six adult, male mongrel dogs were used in this study. Bilateral, Class III, alveolar defects were surgically produced following extraction of the mandibular second premolar teeth and local reduction of the alveolar ridge. After an 8-week healing interval, mucoperiosteal flaps were elevated. P-15/ABM with or without bioabsorbable membranes were implanted into contralateral defects in 10 sites. Two sites received no biomaterial (controls). Mucoperiosteal flaps were advanced over the P-15/ABM or P-15/ABM/M constructs and sutured. Pre- and postaugmentation clinical evaluation was done utilizing periodontal probes and calipers. The animals were sacrificed 12 weeks postaugmentation and block specimens processed for histologic evaluation. RESULTS: Clinical results showed no significant statistical augmentation on the control group (0.0 +/- 0.6 mm). In all experimental sites utilizing P-15/ABM or P-15/ABM/M, relevant ridge augmentation was observed (3.6 +/- 2.0 mm and 2.9 +/- 1.9 mm, respectively). Histologically, all experimental sites showed active bone formation with plump osteoblast and osteoid matrix deposition in the treated area. Bone ingrowth filled the area of the defects treated with P-15/ABM/M. Few P-15/ABM particles were seen in the cellular fibrous tissue surrounding the new formed bone trabeculae. CONCLUSIONS: P-15/ABM with or without membranes can produce a significant clinical ridge augmentation. Bone formation was histologically observed in all test areas. The association of a membrane with P-15/ABM seemed to enhance the process of bone formation.

Absorbable Implants↗
PubMedDate not supplied

New insights into the propagation of fatigue damage in cortical bone using confocal microscopy and chelating fluorochromes.

Fatigue damage in bone occurs in the form of microcracks and plays an important role in the initiation of bone remodelling and in the occurrence of stress and fragility fractures. The process by which fatigue microcracks in bone initiate and grow remains poorly understood. The aim of this study was to investigate the microscopic tissue changes associated with microcracks during crack propagation in cortical bone and the influence of bone microstructure on this process. Cracks were mechanically initiated and extended longitudinally in a two-stage process, in six bovine tibial compact tension specimens. The sequential application of chelating fluorochromes, xylenol orange followed by calcein, allowed the nature of microcrack damage at different stages of propagation to be monitored by laser scanning confocal microscopy. Specimens were imaged at a focal plane 20 microm below the samples' surface, or as a series of z-plane images collected to a maximal depth of 200 microm and 35 microm for x 4 and x 40 objectives, respectively. Z-series image stacks were then reconstructed using Amira 3.0 software. Confocal images showed that xylenol orange localised to the crack surface and did not migrate into the crack's extension following further mechanical propagation. Similarly, calcein stained the extended crack's surface and displayed minimal incorporation within the original crack. High resolution confocal images provided a detailed visual description of the crack's 'process zone', and 'process zone wake'. Additionally, an 'interface region' was revealed, displaying a clear distinction between the end of the first crack and the commencement of its extension. Confocal images of the interface region demonstrated that the extended crack forms a continuum with the pre-existing crack and propagates through the former process zone. Upon viewing the three-dimensional reconstructed images, we found evidence suggesting a submicroscopic tissue involvement in fatigue damage, in addition to the potential influence of vascular canals and osteocyte lacunae on its propagation through the bone matrix. This study has provided new insights into the process of fatigue damage growth in bone and factors influencing its progression through the bone matrix. Confocal microscopy in combination with sequential chelating fluorochrome labelling is a valuable technique for monitoring microcrack growth in bone.

Animals↗
PubMed2004

Characterization of aged osteocalcin fragments derived from bone resorption.

INTRODUCTION: Osteocalcin (OC) is a small bone matrix protein exclusively found in mineralized tissue. OC measured in serum or plasma provides an index of bone formation. In the present study a sensitive inhibition ELISA was established that could quantify fragments derived from the OC Mid-region in human urine. METHODS: The ELISA was based on a monoclonal antibody directed against residues 21-29 of human OC (Mid-OC Urine ELISA). OC fragments were isolated from human urine by immunoaffinity chromatography. OC fragments were purified further by reversed phase high performance chromatography for characterization by N-terminal sequencing and mass-spectrometry. OC fragments were assayed in bone cell culture supernatants and in serum and urine from patients undergoing anti-resorptive bisphosphonate therapy using the Mid-OC urine ELISA. RESULTS AND CONCLUSION: It was demonstrated that the release of OC fragments was highly correlated with osteoclast-mediated pit formation (r2= 0.89) and with an established marker of bone resorption (CTX; r2=0.91). Mid-OC values were decreased markedly after 3 and 10 days of anti-resorptive bisphosphonate treatment further indicating that the marker reflects bone resorption. The molecular characterization revealed that most of these molecules were less than 15 amino acids in length and many contained modified aspartyl residues (D-aspartyl and isoaspartyl) characteristic of aged proteins. The presence of such modifications shows that these molecules have resided in the bone matrix for an extended period and thus they cannot be derived directly from bone formation. In conclusion, these findings demonstrate that OC-fragments are released during osteoclastic bone resorption and that the quantification of specific age-modified OC fragments can provide an index of bone resorption.

Adult↗
PubMed1986

Endosteal new bone formation in the long bones of adjuvant treated rats.

Histopathological changes were examined mainly in the diaphyseal parts of long bones, especially femur in adjuvant-treated male Lewis-SPF rats, with reference to clinical symptoms of chronic osteoarthritis. The diaphyseal bone marrow of long bones in these rats sequentially showed three different processes of chronic pathological changes, which, however, partly overlapped each other. Initially, multiple epitheloid cell granulomas or granulomatous lesions containing fibrin deposits began to appear in the marrow space about 22 days after adjuvant injection, when the joint score of arthritis reached a peak in severity. Secondly, about a week after appearance of the granulomas, there occurred the intramembranous endosteal new bone formation proceeding from the endosteum towards the granulomatous lesions. The bone formation reached a maximum about 64 days after the treatment, when the redness of joints of feet and hands was already sedated. Finally, about 40 days after occurrence of the second event, the newly growing bone matrix began to be actively resorbed simultaneously. On the other hand, in the bone marrow of metaphyseal parts of long bones in these rats, severe acute osteomyelitis was observed from an early stage, with marked destruction of bone trabeculae and simultaneous new bone formation. In the diaphyseal bone marrow of affected long bones, the epitheloid cell granulomas appear to induce the endosteal new bone formation.

Adjuvants, Immunologic↗
PubMed1982

The reaction of the dura to bone morphogenetic protein (BMP) in repair of skull defects.

Trephine defects in the adult rat skull 0.8 cm in diameter, which do not spontaneously heal, were filled with a bovine bone morphogenetic protein (BMP) fraction. The defects healed not only by bony ingrowth from the trephine rim, but also by proliferation of pervascular mesenchymal-type cells (pericytes) of the dura mater. Under the influence of BMP, dural pericytes differentiated into chondroid and woven bone. Between three and four weeks postimplantation, sinusoids formed and the woven bone remodelled into lamellar bone. Concurrently, blood-borne bone marrow cells colonized the bone deposits, and the diploe were restored. Demonstrating that it is soluble in interstitial fluid, and diffusible across a nucleopore membrane (which isolated the bony margins of the skull), BMP induced new bone formation in the underlying dura and complete repair of the defect. The response of the dura to the BMP fraction produced more new bone than the response to allogeneic bone matrix. The BMP-induced repair was dose dependent; the quantity of new bone was proportional to the dose of the implanted BMP.

Animals↗
PubMed2006

Tissue engineering approach to the treatment of bone tumors: three cases of cultured bone grafts derived from patients' mesenchymal stem cells.

A novel approach to the treatment of bone tumors using tissue-engineered implants is reported in this study. The number of mesenchymal stem cells (MSCs) obtained from each patient's bone marrow cells was first increased, and the MSCs were forced to differentiate into osteoblasts followed by bone matrix formation on hydroxyapatite (HA) ceramics. The strong osteogenic ability of the implants, as evidenced by high osteoblastic activity, was confirmed. Consequently, the HA surface was covered with the patient's derived cultured osteoblast/bone matrix. The tissue-engineered HA was used to fill the patient's bone cavity after tumor curettage. Immediate healing potential was found by serial plain radiographs and computed tomograhy images, and no adverse reactions were noted in these patients. The results indicate that tissue-engineered osteogenic ceramics might be an alternative to autologous bone grafts.

Adolescent↗