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PubMed1957

The effects of fluoride feeding on the organic matrix of bones and teeth of pigs as observed by autoradiography after in vitro uptake of Ca45 and S35.

Demineralized sections of fluorinated bones and teeth have been studied by autoradiography following in vitro uptake of Ca(45) or S(35)O(4). The portions of tissue which do not become mineralized (cartilage, prebone, predentine, and precementum) show an increased Ca(45) uptake apparently related to an increase in chondroitin sulfate content in fluorosis. The tissues from the fluoride-fed animals show an increase of in vitro uptake of sulfur in the tissues which become mineralized (bone, dentine, cementum).

Animals↗
PubMed2002

Overview of bone morphogenetic proteins.

STUDY DESIGN: A literature review was conducted. OBJECTIVES: To review the discovery of the bone morphogenetic proteins and describe the bone morphogenetic protein products that will or may be available for clinical use. SUMMARY OF BACKGROUND DATA: Bone morphogenetic proteins comprise the osteoinductive component of several tissue engineering products in late-stage development as replacements for autogenous bone graft, and for bone augmentation and repair. METHODS: The literature on bone morphogenetic proteins was reviewed. RESULTS: Bone morphogenetic proteins were discovered originally on the basis of their presence in osteoinductive extracts of bone matrix. Molecular cloning of bone morphogenetic proteins demonstrated that they are a family of related differentiation factors, each capable of inducing the formation of new bone tissue when implanted. Two of the molecules in clinical use, recombinant human bone morphogenetic protein-2 and recombinant human bone morphogenetic protein-7 (OP-1) are produced in a biotechnology process using recombinant deoxyribonucleic acid technology that offers unlimited supply and substantial control over purity and reproducible activity. A third material, bovine bone morphogenetic protein extract, is extracted from bone, and contains a mixture of bone morphogenetic protein molecules. Each of these molecules, although osteoinductive in vivo, has different physiologic roles and biologic activities in vivo and in vitro. Successful development of a product for use in spinal fusion involves selecting the osteoinductive molecule, the amount of the bone morphogenetic protein required, and the method of delivery, as well as conducting subsequent preclinical and clinical studies to evaluate its efficacy and safety. CONCLUSIONS: On the basis of the data provided in this issue of Spine, some of these bone morphogenetic protein-based products provide for revolutionary therapies in orthopedic practice.

Animals↗
PubMed2000

In vivo osteogenic durability of cultured bone in porous ceramics: a novel method for autogenous bone graft substitution.

BACKGROUND: Bone marrow cells differentiate into bone-forming osteoblasts when cultured in medium supplemented with 15% fetal bovine serum, ascorbic acid, beta-glycerophosphate, and dexamethasone. METHODS: To investigate in vivo osteoblastic activity and bone matrix formation by cultured bone marrow cells, Fischer rat marrow cells were cultured for 2 weeks in porous hydroxyapatite (HA) and then subcutaneously implanted into 7-week-old male syngeneic rats. The implants were harvested after 8 and 52 weeks for biochemical and histological analyses. RESULTS: At both times, formation of lamellar bone accompanied by regeneration of marrow were seen in many of the HA pores. When a fluorochrome (calcein) was administered at 50 weeks after implantation, it was detected in the pores of implants harvested at 52 weeks. Osteoclastic resorption followed by new bone formation was seen in some pores at 52 weeks, indicating that bone remodeling was continuing. The alkaline phosphatase activity of implants harvested at 52 weeks was comparable to that at 8 weeks, whereas the osteocalcin content of the implants harvested at 52 weeks was about twice that at 8 weeks. CONCLUSION: These results demonstrated that there was persistent in vivo osteogenic and hematopoietic activity in the prefabricated bone/HA constructs, and indicated that normal bone tissue was regenerated after grafting of the constructs, which were brittle before implantation. Tissue engineering using HA and cultured marrow cells culture may provide an alternative method of bone transplantation for patients with skeletal disorders, although further in vivo and in vitro experiments are needed.

Alkaline Phosphatase↗
PubMed1979

A simple model for anatomic bone scanning studies.

A simple anatomic model for studying the scintigraphic appearance of various skeletal structures is described. The technique makes use of the fact that technitium pyrophosphate uptake in bone occurs by chemisorption to the surface of crystals in the bone matrix. By soaking clean bones in solutions of technetium pyrophosphate they can be rendered radioactive and subsequently studied by various imaging techniques.

Bone and Bones↗
PubMed2005

The modulation of intra-articular inflammation, cartilage matrix and bone loss in mono-articular arthritis induced by heat-killed Mycobacterium tuberculosis.

Inflammation models for the assessment of anti-rheumatic drug activity utilize a variety of stimuli and sites. However, the determination of cartilage and bone degradation remains time consuming and problematic. A rapid rat model of Mycobacterium tuberculosis monoarticular arthritis with induces of inflammation, as well as patellar cartilage proteoglycan and bone degradation has been reported. This study characterizes this model with respect to the actions of anti-rheumatic drugs. Dexamethasone, cyclosporin and prednisolone inhibited all three parameters. Methotrexate inhibited joint inflammation alone, whilst azathioprine was without effect. Levamisole inhibited cartilage and bone degradation without affecting joint inflammation. NSAIDs were divided in their actions. Naproxen, piroxicam, diclofenac and tiaprofenic acid all inhibited joint inflammation and bone loss, but naproxen and piroxicam both significantly potentiated cartilage proteoglycan loss. This model appears to rely on cellular recruitment at this early stage, the anti-metabolites being ineffective. The modulation of inflammation can result in a protection against cartilage and bone damage in arthritis; however, certain NSAIDs are detrimental to cartilage integrity. The pharmacological manipulation of inflammatory arthritis can therefore dislocate inflammation from its effects on tissue destruction.

Animals↗
PubMed1999

Effects of rat fetuin on stimulation of bone resorption in the presence of parathyroid hormone.

Rat fetuin, which is the rat counterpart of human alpha 2-HS glycoprotein and bovine fetuin, is only detectable in calcified tissues such as bone matrices and dentin, and bone cells such as osteoblasts and osteocytes immunohistochemically. The effect of this protein on bone resorption was examined to study its physiological role in bone metabolism. Rat fetuin increased bone resorption in the presence of low concentrations of parathyroid hormone (PTH), but it had no activity on bone resorption without PTH. The increase in bone resorption by PTH and PTH plus rat fetuin was inhibited by the addition of chymostatin, an inhibitor for cathepsin L. Moreover, we found that when type I collagen from rat was preincubated with rat fetuin, the digestion of rat type I collagen by cathepsin L was increased. These findings suggest that rat fetuin present in bone matrix is important in bone resorption.

Animals↗
PubMed2006

Cell biology of pathologic renal calcification: contribution of crystal transcytosis, cell-mediated calcification, and nanoparticles.

INTRODUCTION: The earliest lesion in the kidneys of idiopathic calcium oxalate stone formers is deposition of calcium phosphate in the interstitium, termed a Randall's plaque. Yet the cellular and molecular factors leading to their formation are unknown. METHODS: The influence of urinary proteins on adhesion of preformed calcium oxalate crystals to rat continuous inner medullary collecting duct (cIMCD) cells was studied in vitro, and cIMCD cells were also exposed to calcifying media containing beta-glycerophosphate for up to 28 days. Renal tissue was obtained from a stone-forming and non-stone-forming individual at the time of nephrectomy. These nanoparticles, isolated from renal stones obtained at the time of surgical resection, were analyzed and propagated in standard cell culture medium. RESULTS: Urinary proteins influence crystal adhesion to renal epithelial cells, and this activity is abnormal in the urine of stone-forming patients. cIMCD cells assumed an osteoblastic phenotype when exposed to the calcifying medium, expressing two bone matrix proteins (osteopontin and bone sialoprotein) that were also identified in the kidney of the stone-forming patient and associated with crystal deposition. Nanoparticles were propagated from the majority of renal stones. Isolates were susceptible to selected metabolic inhibitors and antibiotics and contained conserved bacterial proteins and deoxyribonucleic acid (DNA). CONCLUSIONS: These results suggest new paradigms for Randall's plaque formation and idiopathic calcium oxalate stone disease. It seems unlikely that these events are driven solely by physical chemistry; rather, they are critically influenced by specific proteins and cellular responses, and understanding these events will provide clues toward novel therapeutic targets.

Animals↗
PubMed1987

Considerations regarding the structure of the mammalian mineralized osteoid from viewpoint of the generalized packing model.

The relative magnitudes of mineral, organic and water contents of dense mammalian bone are calculated by a new theory based on recent findings: (1) The neutron diffraction studies of mineralized tissues with different densities demonstrated an inverse relationship between wet density and the equatorial diffraction spacing of the collagen. (2) The neutron studies showed there was very little mineral within the collagen fibrils. (3) A generalized packing model for collagen has been advanced to show how the equatorial spacing can be varied depending on tissue type, water content, and mineral content. (4) The water content of collagen fibrils when calculated from the generalized packing model matches the experimentally determined values for rat tail tendon fibers, bone matrix, and fully mineralized bone. A computational model was developed based on the generalized packing model. It provides a unifying approach to explain many features of mineralized fibrous collagenous tissues. The results are presented as estimates of the mineralized collagen fibril density, the volume fraction of collagen in bone, the density of the extrafibrillar space, the fraction of the e.f. space occupied by mineral and the ratio of mineral within collagen to total mineral content, each expressed as a function of wet bone density. A useful data base, available from previous studies, related mineral, organic and water weight fractions to wet bone density, for a density range from 1.7 g/cc for deer antler to 2.7 g/cc for porpoise petrosal. A second order polynomial was found for each weight fraction component, with bone density as the input variable, with a standard deviation less than 2% of total bone weight. This permits the bone properties to be related to a single variable, the wet bone density. It is seen that compacting the collagen fibrils as well as reducing the organic component weight fraction are two important factors determining the structure of the mineralized osteoid. It was concluded that voids and pore spaces may occupy at least 5% of the bone volume.

Animals↗
PubMed2006

Treatment strategies for skeletal complications of cancer.

Skeletal complications are a common result of many cancers, particularly of multiple myeloma and bone metastases of solid tumors originating in the breast, prostate or lung. A number of treatment options are available, including radiotherapy, radiopharmaceuticals, surgery and chemotherapy. Recently, bisphosphonates have emerged as a promising new treatment option for bone complications of cancer. These agents are potent inhibitors of osteoclast activity that bind to the bone matrix, are released during bone resorption, and are subsequently internalized by osteoclasts, where they interfere with biochemical pathways and induce osteoclast apoptosis. Bisphosphonates also antagonize osteoclastogenesis and promote the differentiation of osteoblasts. As a result, bisphosphonates inhibit tumor-induced osteolysis and reduce skeletal morbidity. Bisphosphonates are generally well tolerated, although they have recently been associated with osteonecrosis of the jaw, a painful and debilitating side effect that is only beginning to be understood. Despite this concern, bisphosphonates are an important tool in the management of skeletal complications of cancer, providing benefits for the treatment of hypercalcemia, osteolytic lesions and fractures, as well as offering amelioration of pain and improvement in quality of life.

Bone Neoplasms↗
PubMed1989

Comparison of histological effects of different bioceramic implants on surgically created periodontal defects in monkeys.

The biological response to the resorbable and nonresorbable bone grafting materials implanted in the surgically created defects was compared in 4 Maccaca cyclopsis. Intraosseous angular defects were created on the mesial side of both upper canines and premolars by an air driven fissure bur. The root surface was planed, then hydroxylapatite (HA) and tricalcium phosphate (TCP) were inserted into the right side defects respectively. The left side canine received no implants and served as the control site. The animals were sacrificed 6 and 16 weeks after the experiment. Histologically, the two implant materials were well tolerated by the surrounding tissues and did not elicit any adverse inflammatory reaction. During the 16 weeks periods, TCP was biodegraded through phagocytosis by histiocytes and multinucleated giant cells. The residual particles were incorporated into the new bone matrix and displayed the bone growth guiding property. HA particles were dense and larger in size with low resorption rate, therefore, encapsulation by fibrous tissue was more commonly seen. Although direct bone deposition adjacent to the HA particle surface was apparently found, new bone formation was observed only at the apical portion adjacent to the host alveolar bone. These findings suggested that HA might rather play the role as a biocompatible filler. However, HA was more effective in blocking the downgrowth of the junctional epithelium. Nevertheless, these two implant materials could not hasten the healing process, because new bone formation was observed to be more distinct in the control site.

Animals↗