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Results for “Parietal Bone”

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At least 109 records · Page 6Linked to original sources
PubMed1999

Bone augmentation by recombinant human BMP-2 and collagen on adult rat parietal bone.

A composite of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen was implanted beneath the cranial periosteum of 10-month-old rats to observe bone development and absorbent change of carrier collagen. The rhBMP-2/collagen onlay implant resulted in active bone formation and the augmented bone was connected directly with the original bone, whereas the collagen alone resulted in neither bone nor cartilage. The ossification process in the rhBMP-2/collagen occurred directly through bone formation, similar to intramembranous ossification. The carrier collagen fibers were found in the woven bone and were completely absorbed at 8 weeks in the presence of rhBMP-2, while the collagen alone implant remained encapsulated by a thin, fibrous connective tissue. Our results indicate that rhBMP-2/collagen is an effective material as a biological onlay implant, showing osteoinductive properties and being completely replaced by new bone. Carrier collagen not only plays a role in rhBMP-2 delivery, but also provides a cell anchorage for cell differentiation and remains as an artificial matrix in woven bone.

Absorbable Implants↗
PubMed1994

Prostaglandin E2 stimulates the production of interleukin-6 by neonatal mouse parietal bones.

The pleiotropic cytokine interleukin-6 (IL-6) is thought to be involved in bone homeostasis. A number of bone resorbing agents have been shown to induce the release of IL-6 from bone. We wished to determine whether prostaglandin E2 (PGE2), which is a mediator of bone resorption, can elicit the production of IL-6. IL-6 was measured by the proliferative response of B9 hybridoma cells and could be completely neutralised by an anti-IL-6 antibody. Parietal bones from neonatal mice were maintained in culture in the presence of indomethacin (10(-6) M) with or without PGE2. The time course and dose-response to PGE2 of IL-6 production were determined. After 6 h in culture, 10(-8) M PGE2 produced significantly more IL-6 than the controls (P < 0.005). PGE2 (10(-6) M) stimulated the production of a mean of 12.8 ng/ml IL-6 over 6 h. Preincubating bones with indomethacin for 20 h prior to a 6 h culture with indomethacin led to a lowering of the production of IL-6 (mean 1.8 ng/ml) compared to bones cultured without the preincubation period (5.8 ng/ml). When the indomethacin preincubation period was used, a significant increase in IL-6 production was found with 10(-9) M PGE2 (P < 0.005), and 10(-6) M PGE2 caused the production of 39.9 ng/ml IL-6 over 6 h. Stripping endocranial and ectocranial membranes from bones demonstrated the membranes to be the major site of IL-6 production. However, intact bones were required for maximal stimulated IL-6 production.

Animals↗
PubMed2007

Correction of sagittal craniosynostosis using a novel parietal bone fixation technique: results over a 10-year period.

Isolated sagittal synostosis is a common form of craniosynostosis affecting roughly 1 in 5,000 children at birth. This results in a scaphocephalic head shape with a characteristically elongated anterior-posterior dimension and narrowed biparietal diameter. We present our experience with the correction of scaphocephaly due to sagittal synostosis using cranial vault reconstruction with a novel form of parietal bone fixation in 21 patients over 10 years. The medial fixation results in a hinging effect whereby transverse brain growth at the squamoid suture is enhanced. This results in excellent cosmetic results that are immediate and durable without the need for postoperative molding helmets. Furthermore, the complications associated with this procedure are limited.

Bone Wires↗
PubMed2000

[Orbital filling using a vascularized parietal bone graft: a case report of rehabilitation with an orbital graft of axial implants].

Orbital and intracranial complications of dental cellulitis are exceptional. The authors report such a case with orbital cellulitis and frontal abscess that dictated orbital exenteration with resection of the eyelids. Before realization of an implant supported epithesis, the orbit was filled with a prefabricated vascularized fascio-osseous parietal bone flap. This allowed placement of two extra-oral fixtures (Nobel biocare) in an antero-posterior axis. In some cases, preimplant orbital bone graft appears to be the only solution when implant placement in the orbital rim is impossible or contra-indicated. Indications, advantages and disadvantages of this technique will be discussed.

Adult↗
PubMed1990

Evidence that adenosine 3',5'-monophosphate mediates hormonal stimulation of prostaglandin production in cultured mouse parietal bones.

The present investigation was undertaken to examine the possible role of cAMP in PTH-stimulated prostaglandin (PG) production in organ cultures of neonatal mouse parietal bones. Cultures were treated with PTH, forskolin, isobutylmethylxanthine (IBMX), and 8-bromo-cAMP (8BrcAMP). We found that similar concentrations of PTH stimulate cAMP formation and increase PG production in this culture system. Forskolin, a direct activator of adenylate cyclase, was also a potent stimulator of cAMP and PG production. The effect was dose dependent, with a maximum at 10(-5) M. The time courses for PTH- and forskolin-stimulated PG production were similar, and there was a close and similar correlation between cAMP production at 15 min and PGE2 production at 6 h for both agents. An increase in PG production was also observed when IBMX, which elevates cAMP levels in cells by inhibiting cAMP phosphodiesterase, or the cAMP analog 8BrcAMP was added to the cultures. In addition, IBMX enhanced the PGE2 responses to PTH, forskolin, and 8BrcAMP. These findings indicate that stimulation of PG production by PTH may be mediated by cAMP.

1-Methyl-3-isobutylxanthine↗
PubMedDate not supplied

Intrapartum ultrasonographic depiction of fetal malpositioning and mild parietal bone compression in association with large lower segment uterine leiomyoma.

With normal flexion of the fetal head prior to and during early normal labor, the fetal biparietal diameter becomes engaged in (and subsequently traverses) the anterior posterior aspect of the pelvic inlet. Thus, the biparietal diameter (characterized sonographically by depiction of the falx cerebri, thalami, and cavum septum pellucidum) will be obtainable upon transverse suprapubic placement of the ultrasound transducer during the first stage of labor. Deflexion, or extension, of the fetal head may be demonstrated sonographically at the level of the cervical spine. Recently, during intrapartum ultrasonographic assessment of a nulliparous patient with a known, large, lower-segment, uterine fibroid, exhibiting poor progress of labor, the fetal biparietal diameter was documented upon midsagittal suprapubic placement of the transducer. In addition, mild compression of the distal parietal fetal bone was demonstrated and considered consistent with compression by the leiomyoma. Following abdominal delivery, due to fetal distress and arrest of descent, significant deflexion of the fetal head (not suspected by intrapartum cervical examinations) and mild parietal bone depression, consistent with the ultrasonographic examination, were noted.

Adult↗
PubMed1991

Activin-A binding and biochemical effects in osteoblast-enriched cultures from fetal-rat parietal bone.

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.

Activins↗