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  • 1
    ISSN: 1432-1076
    Keywords: Hypophosphataemic rickets ; 1,25(OH)2D ; 1α-hydroxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 1974, a 2-year-old boy was diagnosed as having X-linked hypophosphataemic rickets (XLH) because of severe rickets and hypophosphataemia. The vitamin D metabolite concentrations, blood and urine chemistry and renal 25-hydroxyvitamin D3 (25 OHD3)-1α-hydroxlase were measured in 1982 (about 2 weeks after withdrawal of medication). 1α-hydroxylase was 392 pg/mg tissue/20 min in the patient, which was high compared with aged-matched controls (69.7±28.5 pg/mg tissue/20 min, mean ±SD, n=7). Our present studies showed that the 1α-hydroxylase activity in the patient with XLH was elevated. Therefore, the normal or low 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) concentrations in XLH patients could be due to accelerated catabolism of 1,25-(OH)2D3 or abnormally regulated 25OHD3-1α-hydroxylase in response to hypophosphataemia, although significantly elevated above that in normal controls.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral pathology & medicine 28 (1999), S. 0 
    ISSN: 1600-0714
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Ultrastructural observation was performed on a calcifying odontogenic cyst (COC) associated with an odontoma and arising in the right mandibular region of an 8-year-old Japanese boy. Four types of cells were identified in the epithelial layer of the COC. The basal cells were low columnar in shape and contained some intracellular organelles. They were attached to the neighboring cells with a few desmosomes and resembled inner enamel epithelium of the normal enamel organ. The stellate reticulum-like cells, polygonal in shape, possessed desmosomes and many cytoplasmic projections. Some intracellular organelles and a few bundles of tonofilaments were observed in the cyutoplasm. The light oval cells that were pale staining with toluidine blue contained dilated membranous organelles and many relatively evenly distributed tonofilaments. These cells were usually scattered in the vicinity of the focal accumulations of ghost cells, and the cell membrane was discontinuous in parts. The ghost cells contained many bundles of tonofilaments that were 60–240 nm in diameter and arranged in various directions. No intact intracellular organelles were noted in the cytoplasm. They were attached to the neighboring ghost cells with some desmosomes and their cell membrane was discontinuous in parts. A variety of vesicles, 90-450 nm in diameter, were scattered among the tonofilament bundles. Some of these contained needle-like crystals that were considered to be initial calcification sites in ghost cells. These vesicles presented morphological similarities to matrix vesicles, and it is therefore suggested that matrix vesicle-like structures are deeply involved with initiation of calcification of ghost cells in COC.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 56 (1995), S. 246-251 
    ISSN: 1432-0827
    Keywords: Osteogenesis ; Diffusion chamber ; Human osteoblastic cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Osteogenic potential of osteoblastic cells isolated from human bone was evaluated by a diffusion chamber method. Cells placed in diffusion chambers were implanted intraperitcneally into the athymic mice. The diffusion chambers cultured in vivo were harvested and examined after implantation for 6–8 weeks. The content of the chamber was proved by a soft roentogenogram to contain the radioopaque area. Light microscopic study revealed that this area was made up of bone-like nodule. Within the diffusion chambers, the cell layers were observed alongside the interior surface of the membrane filters, and mineralized nodules were formed among the cell layers. The mineralized nodules were confirmed by staining with the von Kossa technique for calcium mineral deposits. In electron microscopic study, the osteoblastic cells had a relatively large nuclei, and an abundant rough endoplasmic reticulum produced numerous extracellular matrix. In the bone-like nodules, the osteoblastic cells were surrounded by a heavily mineralized matrix with nonmineralized matrix separating the osteoblastic cells from the mineralized matrix. The mineralized matrix contained well-banded collagen fibrils. Matrix vesicles and collagen fibrils which were closely associated with mineral deposition were observed at the mineralizing front. These results together with our previous report [13] indicate that isolated human osteoblastic cells possessed osteogenic potential in vivo as well as mineralization activity in vitro.
    Type of Medium: Electronic Resource
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