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Digitale Medien

High concentrations of bioactive glass material (BioGran®) vs. autogenous bone for sinus floor elevation (2002)

Tadjoedin, Ette S. ; De Lange, Gert L. ; Lyaruu, D. M. ; [weitere]

Oxford, UK : Blackwell Science, Ltd

Clinical oral implants research 13 (2002), S. 0

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ISSN: 1600-0501

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: Abstract: In this study, high concentrations of bioactive glass (BG) particles were compared with autogenous bone in their capacity to augment maxillary bone when grafted in the human sinus floor using a split mouth design. Three female patients with severe maxillary atrophy underwent bilateral sinus floor elevation and bone grafting using 80–100% BG particles (300–355 μm in size) mixed with 20% to 0% iliac crest bone particles at one (experimental) side, and 100% iliac crest derived bone particles at the other (control) side. A total of 22 bone biopsies was taken at the time of fixture installation; that is, at 4, 6 and 15 months after grafting, and processed for histology and histomorphometry. At the control (autogenous bone) sides, trabecular bone amounted to 39% of the biopsy volume in the graft (site) at 4 months, almost 41% at 6 months, and 42% at 15 months. This bone contained viable osteocytes and was mostly of mature, lamellar type. At the experimental (BG particles) sides, the graft consisted of 27% of mostly woven (and some lamellar) bone at 4 months, 36% (woven and lamellar) bone at 6 months, and 39% (mainly lamellar) bone at 15 months. The grafted BG particles started to excavate at 4 months and their centers gradually filled with bone tissue. As a consequence, the volume of BG particles in the biopsy decreased from 29% at 4 months to 15% at 6 months and 8% at 15 months. The BG particles appeared to resorb within 1–2 years by dissolution rather than by osteoclastic activity. Parameters for bone turnover (% osteoid surface, % resorption surface) indicated that bone remodeling was very active at both experimental and control sides, during more than 6 months. These results suggest that mixtures of mainly (80–90%) BG particles and some (10–20%) autogenous bone are effective for bone regeneration in the augmented sinus offer 6 months healing time, while about 12 months healing time is needed for 100% BG particles.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1034/j.1600-0501.2002.130412.x

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Digitale Medien

Osteoblast and osteoclast precursors in primary cultures of calvarial bone cells (1986)

Burger, Elisabeth H. ; Boonekamp, Piet M. ; Nijweide, Peter J.

New York, NY [u.a.] : Wiley-Blackwell

The @Anatomical Record 214 (1986), S. 32-40

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ISSN: 0003-276X

Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Medizin

Notizen: Bone cells obtained by digestion of fetal mouse or chicken calvaria were tested for their ability to form or resorb bone in vitro. The isolated cells were precultured for 6 days and subsequently cocultured for 11 days with periosteum-free noninvaded fetal mouse long bone rudiments. Bone formation and resorption during coculture were evaluated by histology and 45Ca release from prelabeled bones. The calvarial origin of cells in cocultures was traced by labeling the cells with 3H-thymidine before coculture, followed by autoradiography.Many osteoblasts and osteoclasts as well as fibroblasts developed from mouse periosteal cells released late in the sequential digestion procedure and previously denoted as “osteoblastlike” (BL). No or few osteoblasts and osteoclasts but many fibroblasts developed from early released cell fractions that have previously been denoted as “osteoclastlike” (CL).Only osteoblasts and fibroblasts but not osteoclasts developed from chicken calvarial cell fractions. The osteoblasts developed primarily from cell fractions from the inner layer of the periosteum, previously denoted as “osteoblastlike” (OB). Cells obtained from the outer layer of the periosteum (PF) gave rise mainly to fibroblasts.These studies show that osteoblast and osteoclast precursor cells are maintained in monolayer cultures of periosteal cell fractions. However, sequential digestion of mouse calvaria does not lead to separation of the two types of bone cells. Rather, osteoclast and osteoblast precursors are released jointly, from the periosteal cell layers closest to the bone surface. In the chicken cell fractions osteoclast precursors are absent after preculture, resulting in a more homogeneous population of osteoblast and fibroblast but not osteoclast precursors.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/ar.1092140106

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Digitale Medien

Function of osteocytes in bone (1994)

Aarden, Elisabeth M. ; Nijweide, Peter J. ; Burger, Elisabeth H.

New York, N.Y. : Wiley-Blackwell

Journal of Cellular Biochemistry 55 (1994), S. 287-299

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ISSN: 0730-2312

Schlagwort(e): osteocyte ; gap junction ; cytoskeleton ; extracellular matrix ; osteocytic osteolysis ; bone membrane ; functional adaptation ; mechanical loading ; strain ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Chemie und Pharmazie , Medizin

Notizen: Although the structural design of cellular bone (i.e., bone containing osteocytes that are regularly spaced throughout the bone matrix) dates back to the first occurrence of bone as a tissue in evolution, and although osteocytes represent the most abundant cell type of bone, we know as yet little about the role of the osteocyte in bone metabolism. Osteocytes descend from osteoblasts. They are formed by the incorporation of osteoblasts into the bone matrix. Osteocytes remain in contact with each other and with cells on the bone surface via gap junction-coupled cell processes passing through the matrix via small channels, the canaliculi, that connect the cell body-containing lacunae with each other and with the outside world. During differentiation from osteoblast to mature osteocyte the cells lose a large part of their cell organelles. Their cell processes are packed with microfilaments. In this review we discuss the various theories on osteocyte function that have taken in consideration these special features of osteocytes. These are (1) osteocytes are actively involved in bone turnover; (2) the osteocyte network is through its large cell-matrix contact surface involved in ion exchange; and (3) osteocytes are the mechanosensory cells of bone and play a pivotal role in functional adaptation of bone. In our opinion, especially the last theory offers an exciting concept for which some biomechanical, biochemical, and cell biological evidence is already available and which fully warrants further investigations. © 1994 Wiley-Liss, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jcb.240550304

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Digitale Medien

Mechanical loading stimulates the release of transforming growth factor-β activity by cultured mouse calvariae and periosteal cells (1995)

Klein-Nulend, Jenneke ; Roelofsen, Jan ; Sterck, Jozien G. H. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 163 (1995), S. 115-119

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ISSN: 0021-9541

Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Medizin

Notizen: We have shown earlier that mechanical stimulation by intermittent hydrostatic compression (IHC) inhibits bone resorption and stimulates bone formation in cultured fetal mouse calvariae (Klein-Nulend et al., 1986, Arthritis Rheum., 29:1002-1009). The production of soluble bone factors by such calvariae is also modified (Klein-Nulend et al., 1993, Cell Tissue Res., 271:513-517). Transforming growth factor-β (TGF-β) is an important local regulator of bone metabolism and is produced by osteoblasts. In this study, the release of TGF-β activity as a result of mechanical stress was examined in organ cultures of neonatal mouse calvariae, in primary cultures of calvariae-derived osteoprogenitor (OPR) cells, and in more differentiated osteoblastic (OB) cells. Whole calvariae and calvariaederived cells were cultured in the presence or absence of IHC for 1-7 days and medium concentrations of active as well as total TGF-β were measured using a bioassay. IHC (maximum 13 kPa, maximal pressure rate 32.5 kPa/sec) was generated by intermittently (0.3 Hz) compressing the gas phase above the cultures. We found that mechanical loading by IHC stimulated the release of TGF-β activity from cultured calvariae by twofold after 1 day. IHC also stimulated the release of TGF-β activity from calvariae-derived cells after 1 and 3 days. The absolute amounts of TGF-β activity released were lower in OPR cells than in OB cells, but the stimulatory effect of IHC was greater in OPR cells. Total TGF-β (active and bound) released into the medium was not affected by IHC. IHC did not change the dry weight of the organ cultures, nor the DNA or protein content of the cell cultures. These data show that mechanical perturbation of bone cells, particularly OPR cells, enhances the activation of released TGF-β. We conclude that modulation of TGF-β metabolism may be part of the response of bone tissue to mechanical stress. © 1995 Wiley-Liss, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jcp.1041630113

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