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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary mineralization in neoplastic tissue was studied in osteosarcoma, correlating observations obtained by SEM to those found with TEM. The process is characterized by extracellular matrix vesicles, distributed in the matrix between the forming neoplastic cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatite crystals within the vesicles is followed by accumulation of apatite crystals, disappearance of the vesicular membrane and formation of calcospherites and calcified fronts. The process described here in neoplastic tissue is essentially similar to primary calcification in normal calcified tissues.
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PMID:The relationship between extracellular matrix vesicles and calcospherities in primary mineralization of neoplastic bone tissue. TEM and SEM studies on osteosarcoma. 15 92

Human osteosarcoma biopsies were studied with the SEM using sequential etching with sodium hypochlorite solutions after removal of aluminium or gold coatings. Osteosarcomas differ from normal hard tissues in that the matrix never proceeds to complete mineralization, so that the specimens fragment on hypochlorite treatment. Details of the fibrillar pattern and calcospheritic type of mineralization pattern can be seen in hypochlorite etched, fractured surfaces and mineralizing fronts.
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PMID:Further observations on the relationship between the matrix and the calcifying fronts in osteosarcoma. 20 68

Cell-attached patch clamp experiments revealed 13-20 pS Na(+)-conducting channels active at normal resting potentials (-28 +/- 1 mV; +/- SEM; 7 cells) in the rat osteosarcoma cell line, ROS 17/2.8. These channels were not blocked by tetrodotoxin, Cd2+, verapamil, or nifedipine. Replacing all cations in the patch pipette except Ca2+ with tetraethylammonium (TEA+) abolishes channel activity; but adding TEA+ to a pipette solution containing only Na+ does not. Depolarization was not necessary to activate these channels, and the open times were much longer than the millisecond open times characteristic of Na+ channels in excitable cells. Current-voltage curves reconstructed from mean single channel currents and mean channel open times resemble L-type Ca2+ current-voltage curves obtained from whole-cell experiments, with current peaks shifted to resting or more hyperpolarized potentials. The voltage sensitivity of these channels has implications on membrane potential stability and on the hyperpolarizing membrane potential spiking activity exhibited by ROS 17/2.8 cells.
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PMID:Continuously active sodium channels in osteoblastic ROS 17/2.8 cells. 166 Jul 43

At the onset of the mineralization of bone, small membranous matrix vesicles are often observed. The information available on the production and release of these vesicles is limited. When treated with 10-20 nM of the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA), the human osteosarcoma cell line U-2 OS developed long cytoplasmic processes connecting adjacent cells. SEM and TEM show that TPA triggers a production and release of matrix vesicle-like membrane vesicles, mainly from the cellular processes. Tetracycline HCl was used to label intracellular bound calcium. The tetracycline HCl label was primarily localized to the end-feet of the cytoplasmic processes, indicating that these contain high concentrations of Ca2+, and to endoplasmic reticulum-like structures in the cell bodies. Together with our previous demonstration of the release of alkaline phosphatase-containing vesicles into the culture medium (Ringbom-Anderson T, Akerman KEO 1992 Calcif Tissue Int 50:533-540), the results presented here indicate that TPA induces a rapid induction of the primary steps of mineralization in U-2 OS osteosarcoma.
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PMID:Production and release of matrix vesicles in the cell processes of TPA-treated human osteoblast-like cells. 805 95

The purpose of this study is to evaluate the biocompatibility of zirconium compared with titanium by the in vitro study using human osteosarcoma cell line (HOS). Various characteristics of the HOS cells cultured on zirconium (99.9%) and titanium (99.9%) discs were investigated. On the colony formation of the HOS cells, there were no differences between the zirconium and titanium in colony size and number. Good proliferation of the HOS cells was observed on the zirconium as well as on the titanium. Morphological observation of the HOS cells by SEM revealed that the cells on the zirconium as well as on the titanium were flat and polygonal in shape with radial pseudopods. Collagen fibers and calcified substances were observed in the matrix of the HOS cells by TEM on the zirconium as well as on the titanium. The calcium of the HOS cell layer was stained well by Dahl's method. Analysis of the HOS cell layer by the Fourier transform infrared spectroscopy indicated that the HOS cells formed the same matrices including the apatite on the zirconium as on the titanium. Measurements of the zirconium and titanium elution into the human saliva indicated that the elution of zirconium was less than that of titanium. These results suggest that zirconium possesses as excellent biocompatibility as titanium.
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PMID:[In vitro study on biocompatibility of zirconium and titanium]. 848 10

Animal cells release traces of material onto glass or silicon surfaces during adhesion and migration. This little studied phenomenon is a widespread and normal concomitant of cell migration. The paper introduces the study of such material. The traces can be visualised by different microscopic techniques (e.g. TIRF, IRM, CLSM, AFM, SEM). Cell traces typical for different cell lines (NIH 3T3 and L929 mouse fibroblasts, mouse macrophages, mouse sarcoma cells and human osteosarcoma cells) are shown and discussed. There are well organised structures such as different linear and nodular elements as well as patches. Traces can extend up to some hundred micrometers from the cell, but the dimensions of the linear elements are in the submicron range. Cell traces are not identical with focal contacts but can include them. A first classification of basic elements is proposed. It allows an estimation of the total volume and surface in comparison to the donor cell. Higher order structures are discussed and a first insight into the protein composition of traces produced by mouse fibroblasts is given. Our observations, together with the cell adhesion literature suggest that the amount of released material, its extent and chemical and structural properties depend on cell type and physiology as well as other external influences. Cell traces in combination with the adhesion pattern of the donor cell should give information about the activity and physiological status of individual cells, the mechanisms of cell locomotion and the molecular composition of the donor cell membrane. The traces might possibly be used as submicron elements for passive electric characterisation and biotechnological applications.
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PMID:Cell traces--footprints of individual cells during locomotion and adhesion. 979 50

Novel bioactive ceramic hollow microspheres with an apparent density in the range 0.8-1.0 g cm(-3) have been developed as microcarriers for 3-D bone tissue formation in rotating-wall vessels (RWV). Hollow ceramic microspheres with a composition of 58-72% SiO2, 28-42% Al2O3 (wt%) and an apparent density 0.8-1.0 g cm(-3) were pretreated in 1.0 N NaOH for 2 h before being coated with synthesized calcium hydroxyapatite (HA) particulate sol. The HA-coated hollow microspheres were sintered for 1 h at 600, 800 and 1000 degrees C. SEM analysis revealed that the grain size and pore size of the calcium phosphate coating increased with the sintering temperature. FTIR analysis showed that crystalline calcium hydroxyapatite was present in the coatings sintered at 600 and 800 degrees C. When sintered at 1000 degrees C, the coating consisted of alpha-tricalcium phosphate. All the coatings adhered well, independent of sintering temperature. The trajectory analysis revealed that the hollow microsphere remained suspended in a rotating-wall vessel (RWV), and experienced a low shear stress (approximately 0.6 dyn cm(-2)). Cell culture studies using rat bone marrow stromal cells and osteosarcoma cells (ROS 17/2.8) showed that the cells attached to and formed 3-D aggregates with the hollow microspheres in a RWV. Extracellular matrix was observed in the aggregates. These data suggest that these hollow bioactive ceramic microspheres can be used as microcarriers for 3-D bone tissue formation in vitro, as well as for the study of the effects of microgravity on bone cell functions.
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PMID:Fabrication, characterization and evaluation of bioceramic hollow microspheres used as microcarriers for 3-D bone tissue formation in rotating bioreactors. 1037 99

Autologous peripheral blood progenitor cell (PBPC) grafts can be contaminated with tumour cells that potentially give rise to relapse following myeloablative therapy and PBPC transplantation. Adeno-associated virus (AAV)-based vectors produced by a new adenovirus-free technique are a gene delivery system which may be applicable for tumour cell purging. To test for the host range of these vectors, solid tumours of clinical relevance and normal CD34+ PBPC were selected as target cells for an AAV-vector, encoding the green-fluorescent protein (GFP) as the indicator gene. At a multiplicity of infection (MOI) of 100: 79.94% +/- 14.36% (mean +/- SEM) of the connective tissue sarcoma cell line (HS-1) and 64.84% +/- 6.91% of the cervical carcinoma cell line cells (HeLa-RC) expressed GFP while the other cell lines tested (1 ovarian tumour, 1 germ cell tumour, 1 osteosarcoma, 2 small cell lung cancer) ranged between 2.82% and 11.94%. Optimising the transduction protocol by use of higher MOIs of up to 500 and by pretreatment with the tyrosine kinase inhibitor, genistein, resulted in up to 95.97% and 94.10% green-fluorescent HS-1 and HeLa-RC cells, respectively. In contrast, only 1.39% +/- 0.51% of the normal haematopoietic CD34+ progenitor cells expressed GFP at a MOI of 100. The differential infectivity between HS-1 and CD34+ cells was maintained after tumour cell spiking in leucapheresis products. Our observations suggest that AAV-based vectors may prove useful for purging of autologous PBPC grafts from solid tumour cells.
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PMID:Superior gene transfer into solid tumour cells than into human mobilised peripheral blood progenitor cells using helpervirus-free adeno-associated viral vector stocks. 1053 60

In order to generate a calcium-phosphate bone cement as a transient replacement for bone defects, we modified Biocement D (Merck Biomaterial GmbH) containing mineralised collagen with osteocalcin, the most abundant non-collageneous protein of bone. Osteocalcin was added to the cement paste during setting in order to control the crystallisation kinetics of hydroxyapatite (HAP) as well as to stimulate the interaction of osteoblasts and osteoclasts with the bone replacement material. Analysis by SEM and AFM shows, that the addition of osteocalcin causes a nanosize microstructure of the calcium cement, which can be explained by inhibited growth of HAP crystals. The fracture strength of the material decreased by incorporation of osteocalcin, pointing onto a higher defect concentration of the crystalline structure. The impact of osteocalcin onto the interaction of bone cells with HAP-Collagen I-cements was studied in a cell culture system using the human osteosarcoma cell line SAOS-2. Results suggest, that osteocalcin might possibly improve the initial adherence of osteoblast-like cells, whereas proliferation of the cells is not effected.
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PMID:Influence of osteocalcin and collagen I on the mechanical and biological properties of Biocement D. 1220 87

Macroporous chitosan scaffolds reinforced by beta-tricalcium phosphate (beta-TCP) and calcium phosphate invert glasses were fabricated using a thermally induced phase separation technique. These porous composite materials were specially designed as both a drug carrier for controlled drug release and a scaffold for bone regeneration. The controlled drug release of antibiotic gentamicin-sulfate (GS) loaded scaffolds and morphology of osteosarcoma MG63 cells cultured on the scaffolds were studied. In comparison with the GS loaded pure chitosan scaffolds, the initial burst release of GS was decreased through incorporating calcium phosphate crystals and glasses into the scaffolds, and the sustained release for more than 3 weeks was achieved. The possible mechanisms for the controlled drug release were investigated by SEM, FTIR, and measurements of the pH values of the PBS solution during the drug release test. SEM micrographs showed no apparent morphological differences for osteoblastic cells grown on the pure chitosan scaffolds and those grown on composite scaffolds. The cells were attached and migrated on these scaffolds, and exhibited a biological appearance, suggesting a good cellular compatibility.
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PMID:Calcium phosphate/chitosan composite scaffolds for controlled in vitro antibiotic drug release. 1220 23


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