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At least 631 records · Page 35Linked to original sources
PubMed1989

Characterization of multiple forms of small collagenous apatite-binding proteins in bone.

A number of small (Mrs 25-28 kDa) collagenous apatite-binding (SCAB) proteins that stain blue with 'Stains-All' have been isolated from fetal porcine bone by sequential extractions with 4M GuHCl (G1), followed by 0.5M EDTA (E), and again with 4M GuHCl (G2). Following purification under dissociative conditions, two types of SCAB proteins both with approximately one-third of their structure being collagenous, were identified in the EDTA extract. One type, which appears to be a novel protein, was revealed in two forms (SCABs 1 and 2, Mrs 25 and 28 kDa) that were recognized by a monoclonal antibody (MBP-322). The second type, SCAB 3, was also present in two forms; one form (SCAB 3a) having a lower affinity for hydroxyapatite than the other (SCAB 3b). These proteins were resistant to CNBr and displayed the chemical and immunochemical properties of the alpha 1 pN-propeptide of type I collagen. A third form of the propeptide (G2-28K) was a prominent component of the second 4M GuHCl extract. The chromatographic properties of serum alpha 1 (I) pN-propeptide were similar to SCAB 3a, indicating that SCAB 3b and G2-28K are post-translationally modified forms of the propeptide produced by bone cells. These propeptides may provide a link between the hydroxyapatite and collagen fibrils, and also have the potential to suppress collagen synthesis during bone resorption.

Animals↗
PubMed1989

Non-apatitic environments in bone mineral: FT-IR detection, biological properties and changes in several disease states.

Resolution enhanced FT-IR spectroscopy shows that non-apatitic environments of phosphate and carbonate ions occur in bone mineral. The spectroscopic characteristics of these environments and their chemical and biological properties are reviewed. The potential effectiveness of FT-IR for the detailed study of bone mineral changes in bone disease is shown by analysis of several samples.

Animals↗
PubMed1991

Electron imaging and diffraction study of individual crystals of bone, mineralized tendon and synthetic carbonate apatite.

A transmission electron microscope study of carbonate apatite crystals isolated from bone and mineralizing tendon, as well as those produced synthetically under approximated-physiological conditions, shows that they are thin irregular shaped plates. Electron diffraction patterns of individual crystals confirm that the large developed crystal face is (100), and that the longest dimensions of the biogenic crystals are aligned with the crystallographic c axes. As the latter are also aligned with collagen fibril axes, the observations provide additional information on the tissue organization itself. The marked similarity between the biologic and synthetic crystals suggests that the biological environment in which the crystals form may not be primarily responsible for controlling their shape.

Animals↗
PubMed1996

Characterization of the apatite crystals of bone and their maturation in osteoblast cell culture: comparison with native bone crystals.

Calcium phosphate crystals deposited in the organic matrix synthesized by chick bone osteoblasts in culture were studied by x-ray and electron diffraction, Fourier transform infrared spectroscopy and chemical composition. The amounts of mineral phase deposited with time and the extent of calcification (% of mineral phase in the tissue) were also determined as a function of time, as were the nature of the changes in the short range order of the crystals. The amount of mineral deposited and the extent of calcification increased with time; the tissue not only contained more crystals of apatite, but the extent of calcification also increased with time as it does in vivo. After 30 days of culture the extent of calcification in the cell culture matrix was similar to that in late chick embryonic and early postnatal chick tibiae. The nature of the CO3 and HPD4 environments were similar to those found in vivo although the concentrations of these ions and the changes in their concentrations with time appeared to develop more slowly in cell culture than they do in vivo. However, the general overall pathway of maturation was similar in cell culture to that observed in vivo.

Animals↗
PubMed2006

Ultrastructural characterization of tissue response to sintered carbonate apatite in rabbit bone.

Our previous in vivo and in vitro studies revealed excellent tissue biocompatibility and osteoconductivity of porous sintered carbonate apatite (CA). The present study focused on the ultrastructural details of cells involved in the degradation of CA and new bone formation. Electron microscopy indicated that multinucleated giant cells (MNGCs) were actively involved in CA resorption. MNGCs extended their irregular cytoplasmic protrusions deeply into the interstitial spaces between CA particles. Endophagosomes were formed by encircling partially dissolved or intact CA crystals via the development of pseudopodia-like cytoplasmic protrusions, the configuration of which was somewhat different from that of the typical ruffled border of bone-resorbing osteoclasts. Subsequently, most CA particles in MNGCs were irregular in shape, suggesting that acidic degradation of CA occurred mainly intracellularly. Mononuclear cells, such as macrophage-like and/or fibroblast-like cells, also took up and degraded some CA. Growth of very thin needle-like crystals was observed in close association with CA. Osteoblasts directly faced the CA and secreted osteoid matrix. At the CA-bone interface, an electron-dense and homogeneous thin layer free of collagen fibers was sometimes observed, suggesting an involvement in CA-bone bonding.

Animals↗
PubMed2006

Effects of apatite foam combined with platelet-rich plasma on regeneration of bone defects.

The objective of this study was to investigate the regenerative effects of apatite foam (AF) combined with platelet-rich plasma (PRP) on bone defects. Critical-sized defects in the tibia of rats were filled with randomly distributed combinations of AF with and without PRP. The animals were killed after three, six, and 12 weeks, and their tissue responses were histologically examined. At three weeks, we found no significant differences in bone regeneration against control group (21.9 +/- 3.1%) when PRP (20.3 +/- 4.2%) and AF (21.6 +/- 2.9%) were used independently of each other. In contrast, significantly (p<0.01) larger amount of bone (32.3 +/- 6.5%) was formed when the defect was filled with PRP-incorporated AF. At six weeks, both PRP (38.1 +/- 3.2%) and AF (39.6 +/- 7.8%) showed significantly (p<0.05) higher rates of bone regeneration than the control, even though they were used independently. Moreover, the amount of regenerated bone significantly (p<0.01) increased in the defect filled with PRP-incorporated AF (76.1 +/- 8.2%). We concluded, therefore, that the combination of PRP and AF may be useful for the regeneration of defected bone.

Animals↗
PubMed1992

[Histological study of tissues surrounding an overloaded mandibular apatite implant and its antagonist teeth at three months].

UNLABELLED: The objective of this study is to compare the degree of the occlusal-bearing ability of 2-piece apatite implant to that of natural dentition. It is conducted by placing implants at M2 and M2 areas of adult monkey. Four months later, the occlusal vertical dimension was raised to apply the occlusal force only on the implants by inserting connected crowns on M3M2M1 and M1M2M3. Three months after loading, the tissues surrounding the implants and the antagonist teeth were histologically examined. RESULTS: The antagonist teeth: The connected antagonist teeth show much bone resorption on the inner surface of the alveolar wall and the roots are partly in direct contact with the bone and intruded. Implant: 1. Due to the resorption from extraction, enhanced remodeling is seen in the compact bone of the experimental site. The degree of remodeling is higher toward the coronal direction. 2. Realigned functionally oblique toward the implant, thickened trabeculae, of both the lamellae and woven bone, supported the implant. 3. Bone formed widely on the buccal and lingual surfaces of the compact bone near the implant. In the areas of close to the direct contact of the implant to the compact bone, remodeling with osteon realignment in the axial direction was observed. 4. Most embedded surfaces of the implant were covered and bound to the bone.

Animals↗
PubMed1994

[Histological study on occlusal bearing capability of apatite implant in maxilla].

The focus of this study is aimed on the degree of occlusal bearing capability of the dense apatite implant in the maxilla and its histological alteration. The implants were placed in the [symbol: see text] areas of the adult monkeys. The vertical dimension was raised by the implants, the opposite [symbol: see text] were splinted together with the connected crowns. At 1, 3 and 7 months after loading, the tissue surrounding the implants and opposing [symbol: see text] was examined histologically with the following results: 1. The formed and newly compacted lamellae and woven bone were seen along the implant supporting the trabeculae and the compact bone that supports the implant and gradually getting thicker until the third month. 2. Realignment and remodelling of the trabeculae and compact bone continuously progressed from 3 months onward. 3. Bone formation and bone remodelling were also observed to have progressed widely towards the neighboring teeth, and bone remodelling in the maxillary sutures similarly occurred. 4. The splinted opposite teeth intruded gradually during the experiment. 5. In some implants, few fracture areas close to the surface were observed in the bone that was in contact with the implant.

Animals↗
PubMed1976

[Infrared-spectroscopic studies of the carbonate apatite structure of dental hard tissues].

Samples of enamel, dentine and cementum were calcined at temperatures of 500 degrees C, 800 degrees C and 1000 degrees C. The infrared spectra recorded at these temperatures were evaluated quantitatively and qualitatively. With increasing temperature, the conversion of the primarily present carbonate apatite into hydroxyapatite increased. At 800 degrees C, a hydroxyapatite proportion of 83% was found. At that, the thermal treatment produced in the dentine an increase in the degree of crystallization from 62% to 100%.

Apatites↗
PubMed2000

Familial osteoarthritis and Milwaukee shoulder associated with calcium pyrophosphate and apatite crystal deposition.

OBJECTIVE: To characterize and define the phenotypes observed in a large Italo-Argentinean kindred with osteoarthritis, chondrocalcinosis, and Milwaukee shoulder (MS). METHODS: Seventy-five members were evaluated with a history, examination, and radiographs of shoulders, spine, hands, and knees. Superior subluxation of the glenohumeral joint was graded using shoulder radiographs and tomography and nuclear magnetic resonance imaging and 3 dimensional computed tomography was performed on selected members. In 31 family members peripheral blood DNA was utilized for genetic linkage analysis of several candidate gene loci previously linked to chondrocalcinosis phenotypes, as well as those implicated in the proper patterning of skeletal elements and cartilage differentiation. In addition, direct sequence analysis of type II collagen gene (COL2A1), the gene that codes for the major structural protein of cartilage, was undertaken in 3 affected and 3 unaffected members of the family. RESULTS: MS was seen in one member of the first generation and 6 members of the 2nd generation, while 8 members of the 3rd generation showed an incomplete form of MS. Isolated superior subluxation of the shoulder was seen in 16 other family members of the 3rd and 4th generations. Osteoarthritis of the spine and peripheral joints was seen in 31 affected members, while chondrocalcinosis was observed in 6 members of the first generation. Shoulder synovial fluid from 2 patients showed the presence of both apatite and calcium pyrophosphate dihydrate crystals. Direct analysis of the COL2A1 gene indicated no known disease determining mutations in affected members, thus excluding this gene as a candidate gene in this family. Genetic linkage to several candidate loci, including the chondrocalcinosis loci on chromosomes 5p and 8q, as well as loci for HOX A and C were also excluded. Linkage analyses of other loci for the HOX B and D genes and the PAX 1 and 9 genes were uninformative in this kindred. CONCLUSION: This kindred illustrates an unusual type of osteoarthritis with secondary intraarticular and periarticular calcification and MS in the most severely affected elderly members. A search for linkage to some potential candidate genes was either excluded or uninformative. Further linkage analysis to identify potential candidate genes is in progress.

Adult↗
PubMed1977

Some ultrastructural aspects of biological apatite dissolution and possible role of dislocations.

High resolution electron microscope techniques now make it possible to study the mineralization of calcified tissues at the crystal structure level. Dislocations play an important part in the course of crystal maturation and modifications. At least two origins of dislocations are known. The first is due to phenomena related to the incorporation of fluoride ions into the lattice. The second is due to mechanical stresses occurring between crystals during their maturation. Dislocations are the starting-points of acid dissolution which proceeds along dislocation-lines, sometimes inducing a splitting of the crystals. In the present study, dislocations have been visualized, either isolated in the crystal core and perhaps the two-dimensional surface representation of a screw-shaped dislocation, or forming nets of dislocations producing a spiral staircase on the sides faces of the crystals. There is evidence of a maturation cycle of the crystals, which may grow, split, coalesce or dissolve; liberated elements and small crystal fragments may allow development of near-by crystals. This remodelling explains the existence of a standard size as well as the perfect fitting of the crystals. These morphological data involve physico-chemical properties of biological apatites.

Acid Etching, Dental↗
PubMed2002

[FTIR investigation on crystal chemistry of CO(2-)3-substituted apatite solid solutions prepared through different methods].

The CO(2-)3-substituted apatite solid solutions were prepared through different methods. The FTIR and XRD measurements were applied to investigate its crystal chemistry properties. The results indicated that the CO(2-)3-substituted sites in the carbonate hydroxyapatite(CHAP) prepared through homogeneous precipitation method are type-B in which [CO3.OH] tetrahedral-coordinations are substituted for [PO4] tetrahedral-coordinations; the ones in the CHAP prepared through solid phase ions exchange method are type-A in which [CO3] triangle-coordinations are substituted for [OH] in column sites; the ones in the carbonate fluorapatite(CFAP) prepared through solid phase reaction method are type-B in which [CO3.F] tetrahedral-coordinations are substituted for [PO4] tetrahedral-coordinations; the ones in the CHAP prepared through sol-gel method are AB mixed-type. The vibrational band psi 3 is splitted into psi 3-1, psi 3-4 and psi 3F. The psi 3F is combined by psi 3-2 (type-A) and psi 3-3 (type-B) in Gaussian function fitting. When Wco(2-)3 < 3.34%, substitution value of type-A increases with the increasing of CO(2-)3 contents. When Wco(2-)3 = 3.34%, substitution value of type-A has maximum. When 3.34% < Wco(2-)3 < 7.52%, substitution value of type-B increases with the increasing of CO(2-)3 contents. When Wco(2-)3 = 7.52%, substitution value of type-B has maximum.

Apatites↗
PubMedDate not supplied

Preparation-induced stability of bioactive apatite coatings.

The stability of the bioactive surface is a major concern in the chemical and physical design of apatite ceramic coatings. In clinical studies, no sintered-hydroxyapatite bulk coating material was present in the surrounding bone tissue after loading periods up to 11 years. In in vitro studies, hydroxyapatite plasma-sprayed coatings dissolved considerably, possibly because of loss of crystallinity during the plasma-spraying procedure. A heat treatment at 600 degrees C reconstituted the crystallinity and promoted the transformation of alpha-tricalcium phosphate into the more stable beta-tricalcium phosphate. Fluorapatite coatings did not lose their crystallinity and had the added advantage of stability as a result of the fluoride ion.

Animals↗
PubMed1991

[Bone substitution with semisynthetic and natural apatite].

Authors demonstrate, based on animal experiment first in the literature of this country both the synthetic and the natural (coral) apatite as a bone substituting material. Complete and partial bone defects in 24 animals of the experience were filled with the materials examined. The speed of healing after the transplantation of the two implants, the mechanical characteristics of the healing bone (fracture solidity) are evaluated using both materials and in both types of the defect. It is stated that evaluable difference could not be observed from the viewpoint of the duration of healing between the two materials whereas considering the fracture solidity the coral substitution proved to be significantly better. The differences between the groups considering the complications (suppuration, pseudoarthrosis) are also assessed.

Animals↗
PubMed2006

Occasional urinary tract infections and urinary depletion effect mask RTA and carbonate-apatite formation in a strong urinary stone former.

We report on a female patient with severe bilateral urolithiasis. A once-off stone analysis performed in the past revealed Mg-phosphate. Occasional UTIs were considered to be the sole cause of stone formation. To date, this assumption had not been checked thoroughly, while stone formation in the patient steadily increased. An inpatient metabolic and analytical work up was performed and stone-growth related urinary alteration was taken into account in urinalysis interpretation. No UTI. NH4Cl-loading test indicated RTA. CT revealed calculi in both kidneys. Carbonate-apatite (CAP) dominates stone composition. Computed urinary composition proximal to stones indicates hypercalciuria. In this patient, occasional UTIs (pH) masked the causes of urolithiasis. Lack of updated stone analysis (CAP), metabolic work up (RTA) and improved urinalysis interpretation (hypercalciuria) concealed the true causes of stone formation.

Acidosis, Renal Tubular↗
PubMedDate not supplied

Trabecular bone response to titanium implants with a thin carbonate-containing apatite coating applied using the molecular precursor method.

PURPOSE: The influence of thin carbonate-containing apatite (CA) coating on the trabecular bone response to titanium implants was investigated. MATERIALS AND METHODS: Thin CA coatings were deposited by a new method known as the molecular precursor method. Using a precursor solution composed of an EDTA-calcium complex, a CA film was deposited on the titanium surfaces. Uncoated and CA-coated titanium were placed in the trabecular bone of the left and right femoral condyles of 16 rabbits. After implantation periods of 2, 4, 8, and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. RESULTS: Histologic evaluation revealed new bone formation around the uncoated and CA-coated implant surfaces after only 4 weeks of implantation. After 12 weeks, mature trabecular bone surrounded all implants. At 4 and 8 weeks of implantation, no difference existed in bone contact between uncoated and CA-coated implants. After 12 weeks of implantation, the CA-coated implant group showed a significantly higher percentage of bone contact than the uncoated implant group. DISCUSSION AND CONCLUSION: The present study demonstrated that thin CA coatings applied using the molecular precursor method showed greater bone-to-implant contact during the healing phase than uncoated controls. The results were similar to those observed with implants with calcium phosphate coatings deposited with a physical vapor deposition technique.

Animals↗
PubMed1988

Polymyositis associated apatite arthritis.

A patient with polymyositis of 12 years' duration developed inflammatory polyarthritis confined to the hands and wrists, with erosions and periarticular calcifications. Her joint disease exemplified that of a previously described subset of patients with polymyositis associated arthritis. In this case, calcific material was aspirated from the right long finger proximal interphalangeal joint and the mineral was analyzed and identified as apatite.

Apatites↗