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At least 685 records · Page 38Linked to original sources
PubMed1996

Use of demineralized bone matrix in hindfoot arthrodesis.

Fifty-five patients considering a hindfoot fusion performed by the senior author over a 5-year period were given the choice of having the fusion augmented by either iliac crest bone graft or demineralized bone graft in a study of the relative efficacy of these 2 methods of bone grafting. Eleven patients underwent subtalar fusion (average age, 40.1 +/- 14.0 years), and 44 had a triple arthrodesis (average age, 54.6 +/- 19.2 years). The most common indications for surgery were posterior tibial tendon insufficiency and traumatic arthritis. There were no significant differences between groups regarding underlying disease, medications, or associated medical conditions. In isolated subtalar fusions, all 3 patients who received an iliac crest bone graft experienced healing, as did 7 of 8 patients who received demineralized bone graft. The eighth patient had a radiographic non-union without clinical symptoms. Complete healing of triple arthrodeses was achieved in 13 of 15 patients who received an iliac crest bone graft and in 29 of 29 patients receiving a demineralized bone graft. There were no intergroup differences in the time to union, which generally was between 3 and 4 months. Intraoperative blood loss was significantly less with demineralized bone graft (33 +/- 25 ml) than with iliac crest bone graft (206 +/- 192 ml). This study demonstrated that demineralized bone graft aids arthrodesis at least as well as does iliac crest bone graft, without the increased blood loss, cost, and postoperative pain associated with iliac crest bone harvest.

Adult↗
PubMed1991

Immunoreactive calbindin-D9K in bone matrix vesicle.

This electron microscope study describes the subcellular occurrence and distribution of immunoreactive calbindin-D9K in the trabecular metaphyseal and compact cortical bone of normal rats, rachitic vitamin-D-deficient rats, and rachitic rats given 1,25-(OH)2D3. Undecalcified bones were embedded in Lowicryl K4M and calbindin-D9K antigenicity was detected by the protein A-gold method. Immunoreactive calbindin-D9K was localized in the cytoplasm and cell processes of osteoblasts and osteocytes. Immunoreactive calbindin-D9K was also found within matrix vesicles and calcifying matrix vesicles, where it lay over the needle-shaped crystallites, at the apparent site of initial crystal formation, but not along the whole crystallites. In fully mineralized bone it occurred at the same site, over the crystallites. Calibindin-D9K was vitamin-D-dependent in the osteoblasts and matrix vesicles, where its presence was correlated with the reappearance of crystallites in 1,25-(OH)2D3-treated vitamin-D-deficient rats. This suggests that immunoreactive calbindin-D9K is involved in mineral deposition in bone matrix vesicles. Abnormal intracellular calcification associated with calbindin-D9K antigenicity in the osteoblasts of 1,25-(OH)2D3-treated vitamin-D-deficient rats indicates that immunoreactive calbindin-D9K may also play a part in abnormal intracellular mineral deposition.

Animals↗
PubMed2006

Augmented bone-matrix formation and osteogenesis under magnetic field stimulation in vivo XRD, TEM and SEM investigations.

Bone is a composite biomaterial, which is formed, when proteins constituting collagen fibers attract calcium, phosphate and hydroxide ions in solution to nucleate atop the fibers. It grows into a hard structure of tiny crystallites of hydroxyapatite, aligned along the long axis of collagen fibers. The present work reports the stimulating effect of static magnetic field on microstructure and mineralization process of bone repair. A unilateral transverse fracture of mid-shaft of metacarpal was surgically created in healthy goats under thiopental sedation and xylocaine analgesia. Two bar magnets (approximately 800 gauss/cm2 field strength) were placed across the fracture line at opposite pole alignment immobilized in Plaster of Paris (POP) splint bandage for static magnetic field stimulation. Radiographs were taken at weekly intervals up to 45 days. Results show that formation of extra-cellular matrix and its microstructure can be influenced by non-invasive physical stimulus (magnetic field) for achieving an enhanced osteogenesis, leading to quicker regeneration of bone tissue in goats. X-ray diffraction (XRD) patterns of treated (magnetic field-exposed) and control samples revealed the presence and orientation of crystalline structures. Intensity of diffraction peaks corresponding to 310 and 222 planes were enhanced with respect to 211 families of reflections, indicating preferential alignment of the crystals. Also, the percent crystallinity and crystal size were increased in treated samples. The study provides a biophysical basis for augmented fracture healing under the influence of semi-aligned static magnetic field applied across the fracture line.

Animals↗
PubMed1999

Effects of Laddec on the formation of calcified bone matrix in rat calvariae cells culture.

Osteoblasts from 21 day-old fetal rats calvaria were isolated using a collagenase digestion procedure. Cells were cultured in the presence of Laddec (a highly purified bovine xenograft) and Bio-Oss (natural bone mineral). Optical microscopic observations showed that osteoblasts attached on the plastic culture dishes and formed close contact with biomaterial particles. By day 5, the osteoblasts formed a confluent monolayer. A cytozymatic method showed intense alkaline phosphatase (ALP) staining around and between the substrate granules of the two materials. By day 14, inverted phase microscopic observations showed that osteoblasts formed bone nodules around and between substrate particles. In addition, at this time, the Von Kossa staining was positive. Using a conventional assay, ALP specific activity was higher in the presence of Laddec than in the presence of Bio-Oss. A quantitative morphological method using image analysis showed that the proportion of mineralized bone formed around biomaterial particles in relation to total bone was increased with Laddec (15% more than with Bio-Oss). Ultrastructural observations by TEM showed the presence of an electron dense collagen-free layer at the biomaterial/bone interface and a collagenous matrix deposited at the periphery, indicating the bioactivity of the biomaterials. These results indicated that Laddec increased the expression of ALP in osteoblast cultures and facilitated the formation of multiple cell layers, providing a culture environment suitable for mineralization.

Alkaline Phosphatase↗
PubMed1999

Clinical utility of demineralized bone matrix for osseous defects, arthrodesis, and reconstruction: impact of processing techniques and study methodology.

The findings of studies on DBM in the surgical management of osseous defects, arthrodeses, and reconstructive procedures have been promising. In general, DBM grafts have supported healing in a timely fashion without complication and with a diminished need to harvest bone from a secondary operative site. Nonetheless, controlled prospective trials are needed to confirm the comparative effectiveness of DBM and to quantitate the benefits of avoiding secondary site autologous bone harvesting. Notwithstanding the known deleterious effects of certain processing steps, current commercial demineralization processes vary widely and use ancillary procedures aimed at attenuating potential residual antigens and pathogens. While some of these procedures may improve or facilitate graft performance (eg, lipid and lipoprotein removal with detergents), others may be deleterious (eg, sterilization with radiation or ethylene oxide) (Table 1). Therefore, it is important that DBM be processed using methods that consistently establish conditions known to preserve DBM's documented osteoinductive potential and that authors appropriately identify processing methods known to have effects on graft performance.

Arthrodesis↗
PubMed2003

Estrogen receptor-beta modulates synthesis of bone matrix proteins in human osteoblast-like MG63 cells.

Estrogens have complex effects on the skeleton, including regulation of modeling and maintenance of bone mass, which vary with cell type and developmental stage. Osteoblasts are key regulators of skeletal matrix synthesis and degradation. However, whether osteocytes, osteoblasts or earlier progenitors mediate estrogen effects, and the importance of estrogen receptors (ERs) alpha and beta, remain unclear. To address estrogen response in human cells closely related to secretory osteoblasts, we studied MG63 cells with ERalpha or ERbeta reduced to low levels by stable transfection of antisense plasmids. Collagen and alkaline phosphatase expression increased with estrogen in wild-type and ERalpha-suppressed cells, but not in ERbeta-suppressed cells. Matrix secretion occurs as osteoblasts cease dividing, and, in keeping with this, cell proliferation was reduced by estrogen except in ERbeta-antisense cells. No effects of estrogen on wild type or ER-suppressed cells were seen in expression of BMP 2, the BMP antagonist noggin, or Indian hedgehog, products that regulate differentiation of osteoblasts. In contrast to expectations that estrogen would modulate bone degradation, RANKL, CSF-1, and osteoprotegerin did not respond measurably to estrogen, regardless of ER status. In keeping with this result, estrogen response was not observed in assays of osteoclast development from CD14 cells supported by wild-type or ER-silenced MG63 cells. Since estrogens are major regulators of bone degradation in vivo, estrogen effects on osteoclasts may depend on interaction with stimuli present in bone but absent in the model studied. cDNA hybridization showed that additional estrogen-binding proteins including ERRalpha and BCAR3 were expressed by MG63, but estrogen effects in ERbeta-silenced cells were small, so these proteins are either minor regulators in MG63 cells, or act in concert with stimuli in addition to estrogen. We conclude that, in the MG63 cell line, estrogen increases synthesis of matrix proteins via ERbeta, and that, in the absence of additional stimuli, these cells are not major mediators of estrogen effects on osteoclast differentiation. Further, ERalpha is probably much more important in earlier stages of skeletal development, such as growth plate response, than in osteoblasts.

Base Sequence↗
PubMed1995

Immunolocalization of bone matrix macromolecules in human tissues regenerated from periodontal defects treated with expanded polytetrafluoroethylene membranes.

Guided tissue regeneration (GTR) is a concept that evolved from the development of membrane barrier techniques which allow the repopulation of periodontal wounds by desirable cells, resulting in a so-called new attachment apparatus. To understand the biological mechanisms involved in membrane barrier-led periodontal healing, the histological localization of macromolecules phenotypical of bone and cementum formation was investigated in regenerating human periodontal tissues harvested after healing by placing barriers on teeth untreatable except by extraction. Using immunolocalization techniques, frozen sections of soft tissues and hard tissues under GTR barriers were stained with antibodies to osteonectin (LB-BON-II) and bone sialoprotein (BSP) (LF-6); alkaline phosphatase (AP) was detected histochemically. Frozen sections of regenerating periodontal tissue demonstrated the presence of spindle-shaped, fibroblast-like cells entrapped in a dense fibrillar extracellular matrix. Rounded cells aggregated to form nodules heavily stained by the Alcian blue method, indicating the presence of proteoglycans and strongly resembling those noted in hard-tissue sections. At the electron-microscopic level, the cytoplasm of the elongated cells had numerous cisternae of endoplasmic reticulum and Golgi saccules, indicating metabolic activity. Striated collagen fibres were scattered throughout the field of the sections. AP-stained soft-tissue sections demonstrated the presence cell-bound and extracellular AP. Osteonectin antibody staining confirmed the presence of this macromolecule in the extracellular matrix, particularly in the area of the cellular nodules. The dense network of connective tissue fibres was also stained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Inhibition of bone matrix apposition by (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (AHPrBP) in the mouse.

To elucidate the mechanism of action of (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (AHPrBP, formerly APD) on bone metabolism, we have studied the influence of low doses of AHPrBP on bone resorption and formation in the mouse. Thirty-five-day-old mice were given daily injections of 0.16, 1.6, or 16 mumol/kg BW per day of AHPrBP for 10 days. At sacrifice biochemical parameters were measured in serum and bone ash, and histomorphometric parameters of bone formation and resorption were determined on undecalcified sections of caudal vertebrae after double 3H-proline and double tetracycline labelings. Serum calcium and 1,25-dihydroxyvitamin D levels remained normal at all dosage levels. Compared to controls, AHPrBP at doses of 1.6 and 16 mumol/kg per day increased the number of osteoclasts and the number of nuclei per osteoclast but markedly decreased the number of acid phosphatase-stained osteoclasts. Thus, AHPrBP appears to inhibit osteoclastic activity in vivo in part through reduction of acid phosphatase activity. At doses of 1.6 and 16 mumol/kg per day AHPrBP reduced serum alkaline phosphatase and the osteoblastic surface and decreased the endosteal osteoid surface and thickness. Both the matrix apposition rate and the mineral apposition rate were progressively reduced at the endosteal level, although they were not significantly changed at the periosteal level. Greater inhibition of bone resorption than bone formation resulted in increased endosteal bone density and bone mineral content. AHPrBP at a dose of 0.16 mumol/kg per day did not alter either the osteoclastic bone resorption or the mineral and matrix apposition rates.

Acid Phosphatase↗
PubMed1986

Growth factors in bone matrix. Isolation of multiple types by affinity chromatography on heparin-Sepharose.

The mineralized matrix of osseous tissue harbors abundant mitogenic activity which is extractable by demineralizing solvents. In bovine bone powder free of blood and cartilage contamination, the volume concentration of mitogens is up to 20 times greater than in serum. Growth factor activity in bone extracts was quantitated on quiescent mouse BALB/c/3T3 fibroblasts, where [3H]thymidine incorporation for 48 h was stimulated up to 200-fold in a linear, dose-dependent manner. Six distinct bone-derived growth factors (BDGFs) have been resolved and partially purified (up to 44,000-fold) on heparin-Sepharose using NaCl gradient elution. Provisionally named by the NaCl molarity at which they elute, these BDGFs include BDGF-0.45 (25% of total activity). This factor is heat-stable and sensitive to dithiothreitol, and displaces 125I-labelled bovine platelet-derived growth factor in a radioreceptor assay. BDGF-0.45 (approximately 50 ng/g of bone) is closely related or identical to bovine platelet-derived growth factor. BDGF-1.1 (10%) has a pI of 5.2 and shows a 16,600-dalton doublet on sodium dodecyl sulfate-polyacrylamide gel electrophoresis Western blots stained with antiserum to bovine anionic fibroblast growth factor. Two activities with high heparin affinity resemble cationic forms of fibroblast growth factor. BDGF-1.5 is the dominant factor in fetal membranous bone (50%), but is less abundant in adult bone (20%). BDGF-1.7, a 17,500-18,400-dalton triplet, is virtually absent in fetal bone (7%) but abundant (30%) in adult bone and may be related to cartilage derived growth factor. Two minor activities, BDGF-0.1 (10%) and BDGF-2.0 (7%) have not been characterized. Proliferation of bovine capillary endothelial cells was strongly supported by BDGFs 1.1, 1.5, and 1.7, but not by 0.45. These four purified BDGFs and the crude bone extract were also strongly mitogenic for rat osteoblasts while depressing alkaline phosphatase specific activity by 2-3-fold. Bone exhibits the most complex spectrum of growth factor activities of any tissue yet described. Bone cells and other indigenous cell types must be considered as possible sources of the BDGFs, in addition to sequestration from blood. Mechanisms for unmasking or release of BDGFs from the mineralized matrix resulting in local action on target cells are undoubtedly important for the development and maintenance of bone tissue.

Age Factors↗