The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Hidehiro Ozawa - One of the best experts on this subject based on the ideXlab platform.
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morphological study of recombinant human transforming growth factor β1 induced intramembranous ossification in neonatal rat Parietal Bone
Bone, 1993Co-Authors: T Tanaka, Y Taniguchi, K Gotoh, R Satoh, M Inazu, Hidehiro OzawaAbstract:Abstract Recombinant human transforming growth factor β1 (rhu TGFβ1) was injected singly or repeatedly for 3–12 days into the periosteum of the right side Parietal Bone of neonatal rats under the period of Bone growth, and the time course of histological changes of the Bone was observed by light and electron microscopy and by enzyme histochemistry. The repeated injections of rhu TGFβ1 at 200 ng/day increased the thickness of the Bone tissue on the treated side, which was about twice the nontreated side value after 12-day injections. On the dermal side, preosteoblasts in the periosteum increased in an early stage of treatment, and thereafter, differentiation into osteoblasts, increase of Bone matrix, Bone marrow cavity formation, and increase of osteoclasts within the Bone marrow cavities were observed. Activation of osteoblasts on the dura mater side was also seen. The single injection of rhu TGFβ1 at 200 ng resulted only in increased osteoprogenitor cell layers and Bone matrix formation in an early stage, and the thickness of the osteoprogenitor cell layers and Bone tissue at 12 days after single injection was comparable to the values on the nontreated side. At 1 μg, however, the osteoblasts were activated, and the osteoprogenitor cell layers and Bone matrix formation were markedly increased. At 12 days, the Bone tissue thickness on the treated side was about twice the nontreated side value, as in the repeated treatment groups. As described above, the 12-day repeated or single treatment of rhu TGFβ1, to the neonatal rat Parietal Bone (membrane Bone) induced marked proliferation of preosteoblasts and promoted Bone formation. No cartilage formation was seen in any group.
Ernesto Canalis - One of the best experts on this subject based on the ideXlab platform.
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further biochemical and molecular characterization of primary rat Parietal Bone cell cultures
Journal of Bone and Mineral Research, 2009Co-Authors: Thomas L Mccarthy, Michael Centrella, Ernesto CanalisAbstract:: Primary Bone cell cultures are used widely to examine the regulation of Bone metabolism by growth factors and hormones. Characterization of this model system is now being conducted at the molecular level to define modulation of gene expression. Cells were obtained from rat Parietal Bone by sequential collagenase digestions. Cell populations were evaluated for Bone-related products, including collagen isoform expression and mRNA levels, alkaline phosphatase activity, and osteocalcin production. Serum-deprived, confluent cultures of the first and second collagenase-released populations produced a lower percentage of total protein as collagen than the third, fourth, and fifth populations, while co-culturing the third through fifth populations resulted in the highest level. Collagen typing on SDS-polyacrylamide gels revealed an abundance of mature type I collagen in all cell populations; type III collagen synthesis was undetectable by this method. This is in contrast to the presence of cytoplasmic mRNA for both type I and type III collagen in all cell populations, suggesting post-transcriptional modulation of type III collagen synthesis. The expression of alkaline phosphatase and osteocalcin was highest in cultures of later released cells, indicating that these cell populations display phenotypic characteristics associated with cells of the osteoblast lineage.
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activin a binding and biochemical effects in osteoblast enriched cultures from fetal rat Parietal Bone
Molecular and Cellular Biology, 1991Co-Authors: Michael Centrella, Thomas L Mccarthy, Ernesto CanalisAbstract:Abstract Activin, a disulfide-linked polypeptide dimer first isolated from gonadal tissue extracts, has amino acid sequence and structural homology with transforming growth factor beta (TGF beta). Along with other activities, TGF beta regulates replication and differentiation and interacts with a defined set of binding sites on isolated Bone cells. To determine if activin shares these properties, recombinant human activin-A (A-chain homodimer) was examined in osteoblast-enriched cultures obtained from fetal-rat Parietal Bone. After 23 h of treatment, 60 to 6,000 pM activin-A increased the rate of [3H]thymidine incorporation into DNA 1.5- to 4.0-fold, and at 600 to 6,000 pM, it enhanced the rate of [3H]proline incorporation into collagen and noncollagen protein by up to 1.7-fold. Like earlier studies with TGF beta in primary osteoblast-enriched cultures, the stimulatory effects of activin-A on DNA and protein synthesis were opposed by parathyroid hormone, and the influence of activin-A on collagen synthesis was independent of cell replication. Binding studies with 125I-activin-A indicated approximately 8,000 high-affinity (Kd = 0.4 nM) and 300,000 low-affinity (Kd = 40 to 50 nM) binding sites per cell. Polyacrylamide gel analysis revealed 125I-activin-A-binding complexes of Mr greater than 200,000 and 73,000 which did not appear to correspond to primary TGF beta-binding sites. These results indicate that activin-A produces TGF beta-like effects in Bone and that some of these effects may be mediated, at least in part, by distinct activin receptors on Bone cells.
T Tanaka - One of the best experts on this subject based on the ideXlab platform.
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morphological study of recombinant human transforming growth factor β1 induced intramembranous ossification in neonatal rat Parietal Bone
Bone, 1993Co-Authors: T Tanaka, Y Taniguchi, K Gotoh, R Satoh, M Inazu, Hidehiro OzawaAbstract:Abstract Recombinant human transforming growth factor β1 (rhu TGFβ1) was injected singly or repeatedly for 3–12 days into the periosteum of the right side Parietal Bone of neonatal rats under the period of Bone growth, and the time course of histological changes of the Bone was observed by light and electron microscopy and by enzyme histochemistry. The repeated injections of rhu TGFβ1 at 200 ng/day increased the thickness of the Bone tissue on the treated side, which was about twice the nontreated side value after 12-day injections. On the dermal side, preosteoblasts in the periosteum increased in an early stage of treatment, and thereafter, differentiation into osteoblasts, increase of Bone matrix, Bone marrow cavity formation, and increase of osteoclasts within the Bone marrow cavities were observed. Activation of osteoblasts on the dura mater side was also seen. The single injection of rhu TGFβ1 at 200 ng resulted only in increased osteoprogenitor cell layers and Bone matrix formation in an early stage, and the thickness of the osteoprogenitor cell layers and Bone tissue at 12 days after single injection was comparable to the values on the nontreated side. At 1 μg, however, the osteoblasts were activated, and the osteoprogenitor cell layers and Bone matrix formation were markedly increased. At 12 days, the Bone tissue thickness on the treated side was about twice the nontreated side value, as in the repeated treatment groups. As described above, the 12-day repeated or single treatment of rhu TGFβ1, to the neonatal rat Parietal Bone (membrane Bone) induced marked proliferation of preosteoblasts and promoted Bone formation. No cartilage formation was seen in any group.
D Goga - One of the best experts on this subject based on the ideXlab platform.
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mechanical characterization and optoelectronic measurement of Parietal Bone thickness before and after monocortical Bone graft harvest design and validation of a test protocol
Journal of Craniofacial Surgery, 2011Co-Authors: B Laure, F Tranquart, Laurent Geais, D GogaAbstract:Abstract Parietal Bone grafts are commonly used in craniomaxillofacial surgery. However, Bone removal may weaken the Parietal Bone and lead to deleterious complications. The aim of our study was to design a test protocol for characterization of the impact resistance of Parietal Bone before and after monocortical Bone graft harvest and to validate an optoelectronic measurement of Parietal Bone thickness. Twelve fresh human cadaver heads were used for the validation study. To evaluate impact resistance, we developed a pendulum Charpy impact testing machine. The impact force was gradually increased until failure (fracture) of the defined Parietal Bone area. According to the protocol, we measured the maximum absorbable energy or impact force to failure. With our test setup, measurement of the impact resistance of Parietal Bone was accurate to within 0.025 J. We defined a range of values and particularly a threshold value. The initial maximal impact must not to exceed 4 J. For more accuracy, we compared 5 nondestructive measurement methods using a surgical navigation system with optoelectronic tracking. We achieved an algorithm based on 2 methods that ensured a measurement resolution of 0.1 mm. Validation of this protocol will allow us to evaluate the loss of strength resulting from Bone removal and the correlation between strength and thickness of the Parietal Bone.
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evaluation of skull strength following Parietal Bone graft harvest
Plastic and Reconstructive Surgery, 2010Co-Authors: B Laure, F Tranquart, Laurent Geais, D GogaAbstract:BACKGROUND: Parietal Bone grafts are commonly used in craniomaxillofacial surgery. The primary aim of this study was to quantify the loss of strength following monocortical Parietal Bone graft harvest. The secondary aim was to establish a correlation between strength and thickness of calvaria. METHODS: Thirty fresh human cadaver heads (nonfrozen, unembalmed heads) were used for this study. Loss of strength was determined by comparing the maximum impact resistance of Bone on the donor side versus the intact side, using a precalibrated pendulum Charpy impact testing machine. Thickness was measured using a surgical navigation system with optoelectronic tracking. RESULTS: Loss of strength at the donor site was 36 percent (p=0.0000000001) for a 40 percent loss of thickness. Although correlation between these two parameters is rather moderate (r=0.46), it is highly significant (p<0.0001). CONCLUSIONS: Although loss of strength is quite significant, serious complications at the donor site are rare. As shown in this study, these risks are nonnegligible. However, because of strong legal pressure, surgeons must carefully weigh the risks incurred by the patient against the expected benefits, whether immediate or deferred. Therefore, the patient should receive well-documented information before such monocortical Parietal Bone graft harvest is performed.
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Evaluation of skull strength following Parietal Bone graft harvest.
Plastic and Reconstructive Surgery, 2010Co-Authors: B Laure, F Tranquart, Laurent Geais, D GogaAbstract:BACKGROUND: Parietal Bone grafts are commonly used in craniomaxillofacial surgery. The primary aim of this study was to quantify the loss of strength following monocortical Parietal Bone graft harvest. The secondary aim was to establish a correlation between strength and thickness of calvaria. METHODS: Thirty fresh human cadaver heads (nonfrozen, unembalmed heads) were used for this study. Loss of strength was determined by comparing the maximum impact resistance of Bone on the donor side versus the intact side, using a precalibrated pendulum Charpy impact testing machine. Thickness was measured using a surgical navigation system with optoelectronic tracking. RESULTS: Loss of strength at the donor site was 36 percent (p=0.0000000001) for a 40 percent loss of thickness. Although correlation between these two parameters is rather moderate (r=0.46), it is highly significant (p
Joel Ferri - One of the best experts on this subject based on the ideXlab platform.
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retrospective evaluation of 211 patients with maxillofacial reconstruction using Parietal Bone graft for implants insertion
Journal of Cranio-maxillofacial Surgery, 2016Co-Authors: Arnaud Depeyre, Sandrine Touzetroumazeille, Ludovic Lauwers, G Raoul, Joel FerriAbstract:Abstract Purpose For a century, autologous Bone grafts have been used in maxillofacial reconstruction. The ideal Bone harvest site and grafting procedure remains a point of contention in regards to obtaining optimal long-term results with sufficient Bone quantity and density without serious complications. More recently, confronted with growing patient requests and biomaterials development, maxillofacial surgeons and dentists have been considering these issues as they relate to pre-implant surgery. This study sought to evaluate implant success rate and complications following pre-implant surgery with Parietal Bone grafting. Materials and methods A retrospective study was carried out on patients who underwent maxillofacial reconstruction of different sites (symphysis, mandibular corpus, maxillary sinus and premaxilla) for the purpose of implant insertion. Results 311 procedures in 211 patients were included. The implant osseointegration rate was around 95%. Clinical follow-up ranged from 10 months to 11 years. A secondary procedure was performed in 6.1% of cases and we noted no serious complications at the harvest site. Discussion With good revascularization and osseointegration of the graft, the use of Parietal Bone leads to an implant success rate similar to that seen in the literature. Moreover, the use of this material results in few infections and low Bone resorption provided there is strict immobilization of the graft and no tension on the soft tissue sutures. Conclusion Parietal Bone grafts technique possess the required qualities for the success of implant surgery, offering results at least as interesting as others using autogenous Bone and with no serious complications on donor site.