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PubMed1985

Calvarial grafts for midface rehabilitation.

Access, pain, prolonged hospitalization, or inadequacy of consistency and quantity of a graft are drawbacks to traditional donor sites of autologous bone for reconstruction of severe midface trauma with bone loss. The sectioning of human skulls resulted in selection of the parietal bone as a technically feasible donor site for obtaining adequate autologous bone for the rehabilitation of generous defects in the floor of the orbit or the anterior maxillary wall. The examination of various animal skulls resulted in the selection of the large canine as an adequate experimental model to evaluate the technique. The parietal bone served as a harvest site, without morbidity, for autologous bone used to fill in the defects in the orbit and anterior malar wall in the live canine model. Subsequently, human autografts of outer cranial table parietal bone provided adequate material to repair severe floor of orbit and maxillary defects with minimal patient discomfort and donor site morbidity.

Adult↗

PubMed2003

Bone augmentation osteogenesis using hydroxyapatite and beta-tricalcium phosphate blocks.

PURPOSE: In this study, we investigated the differences in osteogenesis and resorption between hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) implanted on the parietal bone of rats. MATERIALS AND METHODS: HA and beta-TCP were used in blocks with macropores and micropores. They were implanted between the parietal bone and the cranial periosteum in rats. Osteogenesis around the implanted materials was investigated histopathologically and histomorphometrically at 1, 2, 4, 8, and 24 weeks after surgery. RESULTS: At 2 weeks, osteogenesis from the parietal bone was observed around both materials, and new bone had attached directly to the surfaces of both materials. New bone grew into the pores of the upper regions of both materials with time. The beta-TCP block had a characteristic basophilic reticular structure in which the dissolution of the materials was observed close to the new bone. The HA blocks were stable for 24 weeks, whereas parts of the beta-TCP blocks were fractured and resorbed at 24 weeks. Histomorphometrically, the volume of new bone around HA was larger than that around beta-TCP. There was no remarkable change in the amount of remaining HA, but that of beta-TCP was decreased. CONCLUSION: HA blocks in this model are suitable for onlay grafts because of its stability and osteogenesis, beta-TCP is not stable. Therefore, when beta-TCP blocks are used for onlay grafts, the mechanical stress on the recipient site should be taken into consideration because of resorption and fracture.

Absorbable Implants↗

PubMed2005

Os parietale divisum.

Divisions of the parietal bone are extraordinarily rare, and have been described previously only in skull specimens in the anatomical literature. We report a case of os parietale divisum (divided parietal bone) in an infant with plagiocephaly. A 36-weeks gestation male with multiple congenital anomalies presented to the deformational plagiocephaly clinic at 11 weeks of age. CT imaging demonstrated a suture dividing the left parietal bone into two segments. He had a plagiocephalic appearance, with the greater occipital and parietal protuberances ipsilateral to the abnormal left parietal suture, and a correspondingly flatter right occiput. Head circumference was in the normal range, and the anterior fontanelle was patent and of normal size. He had mild right-sided right frontal and malar protuberance. Mandibular asymmetry was noted with a chin-point to the right of midline. He had a left-sided head tilt. He was treated with cranial molding helmet therapy for his head shape and physical therapy for his head tilt. After 16 months of helmet therapy, he had little improvement of his head shape. This case is an in vivo presentation of a rare variant, os parietale divisum.

Abnormalities, Multiple↗

PubMed1985

Mammalian collagenase predisposes bone surfaces to osteoclastic resorption.

The cell-free endocranial surface of young adult rat parietal bones was used as a substrate for bone cell-derived mammalian collagenase. Incubation of parietal bones in a concentration of enzyme comparable to that secreted by osteoblastic cells in vitro caused destruction of surface osteoid, and resulted in exposure of mineral onto the bone surface. Bones so pre-treated were considerably more susceptible to osteoclastic resorption than bones pre-incubated in the absence of collagenase. These results are consistent with the view that the osteoid layer which covers bone surfaces acts as a barrier to osteoclastic contact with underlying, resorption-stimulating bone mineral; and that cells of the osteoblastic lineage induce osteoclastic resorption through collagenase secretion which, by digestion of the surface osteoid, exposes bone mineral to osteoclastic contact.

Animals↗

PubMed2007

Histological findings of long-term healing of the experimental defects by application of a synthetic biphasic ceramic in rats.

Calcium phosphate ceramics are generally biocompatible and can develop interactions with human recipient bone. Therefore, they can be widely used in the field of periodontology and dentistry. The purpose of this investigation was to assess the long-term histological bone healing results of experimentally created critical size parietal bone defects in rats. Twelve Wistar rats were used in this investigation. Two 6-mm wide, symmetrical, and circular critical size defects were created in each parietal bone of the animals. While the right defects filled with granular implant (Ceraform), the symmetrical defects were taken as controls. Eighteen months after implantation, rats were killed and defects including the biomaterial with surrounding bone was taken for histological examination. Serial histological sections were cut across the defects and stained for the histological analysis. Both control and Ceraform implanted regions contained dense collagenous tissue. In the implantation site, multinuclear giant cells were observed around the material. On the other hand, there were no necrosis, tumour, and infection in the implantation region. There was no statistical difference between the control and ceraform implanted groups when the bone formation results were compared (p > 0.05). In conclusion, the results revealed that this material is biocompatible and does enhance the new bone building despite the long-term observation period. Although this biphasic ceramic shows within the limits of the study as a less resorptive and not osteoconductive properties, it can be considered as a biocompatible bone defect filling material having a limited application alternative in dentistry and medicine.

Animals↗

PubMed2005

A comparison of skeletal chord-length distributions in the adult male.

In radiation protection, skeletal dose estimates are required for the tissues of the hematopoietically active bone marrow and the osteogenic cells of the trabecular and cortical endosteum. Similarly, skeletal radiation dose estimates are required in therapy nuclear medicine in order to develop dose-response functions for myelotoxicity where active bone marrow is generally the dose-limiting organ in cancer radioimmunotherapy. At the present time, skeletal dose models in both radiation protection and medical dosimetry are fundamentally reliant on a single set of chord-length distribution measurements performed at the University of Leeds in the late 1970's for a 44-y-old male subject. These distributions describe the relative frequency at which linear pathlengths are seen across both the marrow cavities and bone trabeculae in seven individual bone sites: vertebrae (cervical and lumbar), proximal femur (head and neck), ribs, cranium (parietal bone), and pelvis (iliac crest). In the present study, we present an alternative set of chord-length distribution data acquired within a total of 14 skeletal sites of a 66-y-old male subject. The University of Florida (UF) distributions are assembled via 3D image processing of microCT scans of physical sections of trabecular spongiosa at each skeletal site. In addition, a tri-linear interpolation Marching Cube algorithm is employed to smooth the digital surfaces of the bone trabeculae while chord-length measurements are performed. A review of mean chord lengths indicate that larger marrow cavities are noted on average in the UF individual for the cervical vertebrae (1,038 vs. 910 microm), lumbar vertebrae (1,479 vs. 1,233 microm), ilium (1,508 vs. 904 microm), and parietal bone (812 vs. 389 microm), while smaller marrow cavities are noted in the UF individual for the femoral head (1,043 microm vs. 1,157 microm), the femoral neck (1,454 microm vs. 1,655 microm), and the ribs (1,630 microm vs. 1,703 microm). The mean chord-lengths for the bone trabeculae show close agreement for both individuals in the ilium (approximately 240 microm) and cervical vertebrae (approximately 280 microm). Thicker trabeculae were seen on average in the UF individual for the femoral head (ratio of 1.50), femoral neck (ratio of 1.10), lumbar vertebrae (ratio of 1.29), and ribs (ratio of 1.14), while thinner trabeculae were seen on average in the UF individual for the parietal bone of the cranium (ratio of 0.92). In two bone sites, prominent discrepancies in chord distribution shape were noted between the Leeds 44-y-old male and the UF 66-y-old male: (1) the bone trabeculae in the ribs, and (2) the marrow cavities and bone trabeculae within the cranium.

Adult↗

PubMed2006

FGF9 can induce endochondral ossification in cranial mesenchyme.

BACKGROUND: The flat bones of the skull (i.e., the frontal and parietal bones) normally form through intramembranous ossification. At these sites cranial mesenchymal cells directly differentiate into osteoblasts without the formation of a cartilage intermediate. This type of ossification is distinct from endochondral ossification, a process that involves initial formation of cartilage and later replacement by bone. RESULTS: We have analyzed a line of transgenic mice that expresses FGF9, a member of the fibroblast growth factor family (FGF), in cranial mesenchymal cells. The parietal bones in these mice show a switch from intramembranous to endochondral ossification. Cranial cartilage precursors are induced to proliferate, then hypertrophy and are later replaced by bone. These changes are accompanied by upregulation of Sox9, Ihh, Col2a1, Col10a1 and downregulation of CbfaI and Osteocalcin. Fate mapping studies show that the cranial mesenchymal cells in the parietal region that show a switch in cell fate are likely to be derived from the mesoderm. CONCLUSION: These results demonstrate that FGF9 expression is sufficient to convert the differentiation program of (at least a subset of) mesoderm-derived cranial mesenchyme cells from intramembranous to endochondral ossification.

Animals↗

PubMed1992

Intracellular localization and translocation of 1 alpha, 25-dihydroxyvitamin D3 receptor in osteoblasts.

The intracellular localization and translocation of the 1 alpha,25-dihydroxyvitamin D3 receptor (1 alpha,25(OH)2D3 receptor) in osteoblasts of mouse parietal bone and MC3T3-E1 cells were examined immunocytochemically using a rat monoclonal antibody to 1 alpha,25(OH)2D3 receptor. In osteoblasts of parietal bones in vivo, immunoreactivity for 1 alpha,25(OH)2D3 receptor was detected not only in the nuclei but also in lysosomal structures, and also sparsely in the cytoplasmic matrix. The transport of 1 alpha,25(OH)2D3 receptor was investigated immunocytochemically after incubation with 1 alpha,25(OH)2D3. In osteoblasts of parietal bones, after 1 min incubation with 10(-8) M 1 alpha,25(OH)2D3, the perinuclear cytoplasm showed intense immunoreactivity for 1 alpha,25(OH)2D3 receptor. After 10 min incubation, immunoreactivity was intense in the nuclei, especially in the heterochromatin. In MC3T3-E1 cells, after 1 min incubation with 1 alpha,25(OH)2D3, immunoreactivity for 1 alpha,25(OH)2D3 receptor was found in the form of a fibrillar structure extending radially to the periphery of the cells. The immunostaining pattern of anti-1 alpha,25(OH)2D3 receptor was similar to the distribution of microtubules stained with anti-beta-tubulin antibody. After 10 min incubation, the nuclei showed intense immunoreactivity for 1 alpha,25(OH)2D3 receptor. Incubation with colchicine dissociated the fibrillar structures and inhibited the intranuclear localization of the 1 alpha,25(OH)2D3 receptor. These findings suggest that the 1 alpha,25(OH)2D3 receptor is located in the nuclei, in lysosomal structures and also sparsely in the cytoplasmic matrix of osteoblasts in vivo, and that the receptor is transported to the perinuclear cytoplasm via microtubules to be then translocated into the nucleus, especially into the heterochromatin.

Animals↗

PubMed1995

The effect of glucocorticoids on osteoblast function. The effect of corticosterone on osteoblast expression of beta 1 integrins.

Prolonged treatment with glucocorticoids is known to produce osteoporosis, which is characterized by a decrease in bone mass. Therefore, we studied the effect of glucocorticoids on the formation of bone and on the expression of beta 1 integrins in a mineralizing organ culture of fetal rat parietal bone. Integrins are a family of integral membrane glycoproteins that mediate the adhesion of cells to extracellular matrix macromolecules and affect the growth and differentiation of cells. In situ hybridization with a 32P-labeled beta 1 integrin cDNA probe was performed on parietal bone, treated with or without 100-nanomolar corticosterone for ninety-six hours, to localize and assess the levels of beta 1 integrin mRNA quantitatively. Corticosterone decreased beta 1 integrin mRNA in the osteoblast layer but not in the periosteum. Northern blot analysis demonstrated a 62 per cent decrease in the levels of beta 1 integrin mRNA in the osteoblast layer of bone that had been stripped of its periosteum. Immunofluorescence microscopy confirmed these results, as they demonstrated a decrease in the levels of beta 1 integrin protein predominantly in the osteoblast layer. This effect was dependent on the concentration of corticosterone. During ninety-six hours of culture, the calcium content and the dry weight of control parietal bone increased 157 per cent and 57 per cent, respectively. However, treatment of these cultures with 100-nanomolar corticosterone inhibited calcification by 24 per cent. The administration of glucocorticoid had no significant effect on the DNA content or dry weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1998

[A case of diploic epidermoid invading intradurally, which was diagnosed by MR diffusion-weighted image].

A case of diploic epidermoid in the right parietal bone was presented. A 66-year-old male was admitted to our hospital because of aphasia. Plain skull radiogram showed an osteolytic lesion in the right parietal bone. Computed tomography revealed a mass with destruction of the parietal bone extending from an inner to an outer table. The mass was shown by MR imaging as hypointensity on the T1-weighted image and as hyperintensity on the T2-weighted image. The hyperintensity became more remarkable by using a diffusion technique. Based on these findings, a preoperative diagnosis of right parietal epidermoid was made. The mass was totally removed and diagnosed pathologically as epidermoid. It was concluded that diploic epidermoid invading intradurally could be differentiated from other osteolytic tumors by using MR diffusion-weighted image.

Aged↗

PubMed2006

Repair of bone defects treated with autogenous bone graft and low-power laser.

Because bone healing at the graft site is similar to a fracture repair, the purpose of the present study was to evaluate the effects of low-power laser irradiation on the repair of rat skull defects treated with autogenous bone graft. A defect measuring 3 mm in diameter was produced in the left parietal bone and filled with an autogenous bone graft obtained from the right parietal bone. The animals were divided into 3 groups of 20 rats each: nonirradiated control, irradiated with 5.1 J/cm, and irradiated with 10.2 J/cm. The laser (2.4 mW, 735 nm, 3.4 x 10 W/cm, 3-mm spot size) was applied three times per week for 4 weeks. Greater volume of newly formed bone was observed in the irradiated group with 10.2 J/cm. In both irradiated groups, a greater volume of newly formed bone occurred only in the first 2 weeks. The results demonstrated that laser irradiation at the grafted site stimulated osteogenesis during the initial stages of the healing process in a skull defect of the rat and that this effect was dose dependent.

Analysis of Variance↗

PubMed1989

Effects of dexamethasone on expression and maintenance of cartilage in serum-containing cultures of calvaria cells.

The effects of dexamethasone on the ability of cells enzymatically isolated from 21-day fetal rat calvaria to produce cartilage in vitro has been investigated. Primary cultures of single-cell suspensions of rat calvaria were grown for up to 28 days in vitro in alpha-minimal essential medium containing 15% fetal bovine serum, 50 micrograms/ml ascorbic acid, 10 mM Na beta-glycerophosphate and dexamethasone at concentrations of 1 microM to 1 nM. Two types of nodules were present in dexamethasone-containing cultures. One has been characterized previously as bone (Bellows et al. 1986). The second morphologically resembled hyaline cartilage, possessed a strong Alcian blue-positive matrix and contained type-II, but not type-I, collagen. Both bone and cartilaginous nodules were spatially distinct and developed in isolation from each other. Cartilaginous nodules were found in the highest number at a dexamethasone concentration of 100 nM. Time-course experiments revealed that while the number of bone nodules increased continuously at least to day 28, the number of cartilaginous nodules remained constant after cultures had reached confluency. When cells were isolated separately from frontal and parietal bones and sutural regions, the greatest number of cartilaginous nodules developed from parietal bones. Since 21-day fetal rat calvaria contains 2 distinct patches of cartilage at the periphery of the parietal bones, it seems likely that this cartilaginous tissue is the origin of the cartilage cells. The results demonstrate that cultures of rat calvaria cells contain chondrocytes and possibly chondroprogenitor cells that are distinct from osteoprogenitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

[Chemical embolization using estrogen for aneurysmal bone cyst of the skull: case report].

A case of aneurysmal bone cyst of the fronto-parietal bone was reported. The patient was a 48-year-old female with the complaints of conjunctival hyperemia and exophthalmus of the right side. Right selective externography revealed both arteriovenous fistula between right middle meningeal artery and diploic vein, and abnormal venous pooling draining into right superior ophthalmic vein. These symptoms probably caused by the increased intraorbital venous pressure in the right side. Skull plain film and CT scan showed blow-out appearance of right fronto-parietal bone in accordance with the enlargement of diploic space. The bulged area and the rest of the affected part of the bone presented faintly coarse "soap bubble" pattern. And the affected bone, being radiolucent, had well demarcated borders which are distinct and smooth, with faint sclerosis. Both arteriovenous fistula and clinical symptom have disappeared completely by the continuous injection of conjugated estrogen into the right external carotid artery. This is the first case that proved chemical embolization using estrogen will effect a cure in the treatment of aneurysmal bone cyst.

Bone Cysts↗

PubMed1989

Brain chemiluminescence and oxidative stress in hyperthyroid rats.

Newborn Wistar rats were made hyperthyroid by injection of tri-iodothyronine and assayed for survival, brain oxygen uptake, brain chemiluminescence and activity of antioxidant enzymes. Brain chemiluminescence was measured (1) by removing the parietal bones or (2) through the translucid parietal bones. Control animals showed a brain chemiluminescence of 130 +/- 12 c.p.s./cm2 and 99 +/- 10 c.p.s./cm2 for procedures (1) and (2) respectively. Hyperthyroid rats showed increases in the spontaneous brain photoemission of 46 and 70% compared with controls, measured by procedures 1 and 2 respectively. The hyperthyroid state did not modify the oxygen-dependent chemiluminescence of brain homogenates. The hyperthyroid animals showed a 30% increase in the oxygen uptake of brain slices and a dramatic shortening of life-span to about 16 weeks. Superoxide dismutase (the Cu-Zn enzyme), catalase and Se-dependent glutathione peroxidase activities of brain homogenates were increased by 18, 36 and 30% respectively in the hyperthyroid animals. Isolated brain mitochondria produced 0.18-0.20 nmol of H2O2/min per mg of protein in state 4 in the presence of succinate as substrate. No difference was observed between control and hyperthyroid animals. It is concluded that hyperthyroidism leads to hypermetabolism and oxidative stress in the brain. The increased levels of oxygen and peroxyl radicals may contribute to premature ageing in these animals.

Animals↗

PubMed1996

Inhibition of prostaglandin synthesis leads to a change in adherence of mouse osteoclasts from bone to periosteum.

When mouse parietal bones were incubated for 1 day in medium containing indomethacin (Ind), the number of tartrate-resistant acid phosphatase-positive osteoclasts (TRAP+OC) counted on the bone surface was drastically reduced. This reduction did not occur with calcitonin or if the endocranial membrane (periosteum) was removed prior to incubation with Ind. The aim of this work was to determine the mechanism involved. TRAP+OC were found to be increased on the endocranial membrane adjacent to the resorbing surface after Ind treatment, compared with cultures supplemented with parathyroid hormone (PTH) or prostaglandin E2 (PGE2). However, this increase accounted for only half of those lost from the bone surface. TRAP negative osteoclasts were also seen on the membrane and, to a lesser extent, on the bone. Increased TRAP specific activity could be extracted from the endocranial membranes of bones incubated with Ind compared with PGE2 controls. When bones that had been exposed to Ind were then cultured for 1 day in PGE2, an increase in TRAP+OC occurred. This increase was blocked by the removal of the endocranial membrane prior to incubation with PGE2. We conclude that when prostaglandin production ceases, TRAP+OC become less adherent to bone and more adherent to the endocranial membrane. Stimulators of bone resorption appear to reverse this process.

Acid Phosphatase↗

PubMed1990

Infantile myofibromatosis with a solitary lesion in the skull--case report.

The term "infantile myofibromatosis" was coined in 1981 to describe a rare type of soft-tissue tumor in infants. Solitary lesions are usual, but extremely rare in the skull. An infantile case involving a lesion in the left parietal bone is described. The patient was a 6-month-old girl admitted with a mass measuring 2 x 2 cm in the left parietal region. Skull x-rays showed an osteolytic lesion with a sclerotic margin in the parietal bone. Computed tomographic (CT) scans revealed a low-density mass with homogeneous enhancement. The tumor adhered to the dura and had destroyed the left parietal bone. Histological examination disclosed spindle-shaped cells arranged in short bundles and abundant vasculature. Phosphotungstic acid hematoxylin staining revealed longitudinal fibrils resembling myofibroblasts. This is the first report in which CT findings are described in a case of infantile myofibromatosis with a solitary lesion occurring in the skull.

Female↗

PubMed1986

[A case of multiple myeloma showing intracranial hypertension due to large cranial mass lesions].

It is well known that the case of multiple myeloma shows punched-out lesions of the cranium without intracranial hypertension. In this paper a case of multiple myeloma is reported showing intracranial hypertension due to a large tumor that developed in the left parietal bone. There are only 13 case reports about cranial mass lesion of multiple myeloma since 1928. A 52 year-old female was admitted to Iwate Prefectural Isawa Hospital suffering from headache, nausea and vomiting. She had been already diagnosed as multiple myeloma and treated with chemotherapy using Cyclophosphamide, Melphalan and Prednisolone for 2 years. On admission, a large subcutaneous mass was presented on the left parietal region. Craniogram revealed large osteolytic lesion of the left parietal bone and 3 punched-out lesions of the frontal bone. CT scan revealed a large mass lesion in the left epidural space, diploe and subcutaneous space. Angiography showed avascular area. Brain scintigram showed diffuse hot area. Other skeletal bones showed no abnormality. Laboratory examination revealed high concentration of gamma-globulin and high erythrocyte sedimentation rate. Electrophoresis showed high value of immunoglobulin G; immunoglobulin assay was as follows: IgG-6000 mg/dl, IgA-150 mg/dl, IgM-410 mg/dl, IgE-0 mg/dl. Serum electrolytes were within normal limits. Urine didn't include Bence-Jones protein. The patient was diagnosed as multiple myeloma suffering from intracranial hypertension caused by large tumor which developed in the left parietal bone. On the operation, large tumor was existed in the epidural and subcutaneous space invading into the diploe but without infiltration into the dura mater or cerebral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMed1990

Comparison of the effects of synthetic human parathyroid hormone (PTH)-(1-34)-related peptide of malignancy and bovine PTH-(1-34) on bone formation and resorption in organ culture.

We have compared the effects of synthetic amino-terminal human PTH-(1-34)-related peptide (PTHrP) of malignancy with those of synthetic bovine PTH-(1-34) in cultures of half-calvariae from 21-day-old fetal rats and of parietal bones from 7-day neonatal mice. Incorporation of [3H] proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP), and percent collagen synthesis (PCS) were measured in both systems. Incorporation of [3H]thymidine and cAMP production were measured in fetal rat calvariae. Production of prostaglandin E2 and I2 and bone resorption, as assessed by release of previously incorporated 45Ca, were measured in mouse parietal bones. The effects of PTHrP and PTH were qualitatively similar. At 96 h CDP in rat calvariae was decreased by PTH at a concentration as low as 0.01 nM, while similar effects were seen with PTHrP at 0.1 nM. Effects on NCP were small, so PCS was reduced. At 24 h [3H]thymidine was not altered, but CDP and PCS were decreased by both PTH and PTHrP. cAMP production was increased in fetal rat calvariae at 30 min. Both PTH and PTHrP increased 45Ca release at low concentrations and prostaglandin production at high concentrations in mouse parietal bones. While PTH was about 10-fold more potent than PTHrP, there was no qualitative difference in the responses. These studies further suggest that PTHrP affects bone through the PTH receptor.

Animals↗