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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 51 (1992), S. 291-297 
    ISSN: 1432-0827
    Keywords: Bone ; Osteoblast ; Cyclosporin A ; Attachment ; Proliferation ; Alkaline phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of the immunosuppressive drug cyclosporin A (CsA) were evaluated on ROS 17/2.8 cells in vitro. ROS cells were treated with CsA (0, 0.5, 1.0, 5.0 μg/ml) for 3 days with and without bovine parathyroid hormone (bPTH) (1–34) 10 nM. CsA at 0.5, 1.0, 5.0 μg/ml without PTH and at 5.0 μg/ml in the presence of PTH significantly inhibited proliferation, as determined by a tetrazolium colorimetric assay. In addition, ROS cell number was significantly reduced at 3 and 4 days with CsA (5.0 μg/ml) without affecting cell viability. Incorporation of [3H]-thymidine into DNA was significantly reduced by 3.0 and 5.0 μg/ml CsA after 12 and 24 hours exposure. Basal and 1,25-dihydroxyvitamin D3-stimulated alkaline phosphatase levels in confluent ROS cells were reduced (P〈0.05) with CsA (1.0 and 3.0 μg/ml). Pretreatment of ROS 17/2.8 cells with CsA did not alter PTH-stimulated cAMP levels or [125I]-PTHrP binding to ROS cells. CsA treatment of ROS 17/2.8 cells induced a spindle-shaped appearance with loss of attachment in confluent cultures. When ROS cells were cultured in CsA-containing media, cellular attachment at 6 and 12 hours was reduced (P〈0.05) compared with untreated ROS cells. These findings indicate that CsA was capable of inhibiting proliferation, cell number, mitogenesis, alkaline phosphatase levels, and cell attachment of ROS cells without affecting PTH binding or cAMP levels. This direct effect of CsA on osteoblasts may be important in changes of bone remodeling observed in CsA-treated humans and animals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0827
    Keywords: Diphosphonates ; Bone Morphology ; Bone Enzymes ; Mineral Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Dichloromethylene diphosphonate (Cl2MDP) was given at doses of 4 mg/kg and 10 mg/kg daily for 7 days to adult thyroparathyroidectomized rats fed a low calcium diet. Primary metaphyseal trabeculae in Cl2MDP-treated rats were more numerous and longer than in controls. The light and electron microscopic appearance of osteoblasts, osteocytes and osteoclasts were unaltered by Cl2MDP. Bone alkaline phosphatase was significantly elevated in rats given Cl2MDP but adenosine triphosphatase activity was unchanged. Bone fat-free weight, fat-free minus ash weight, and bone calcium and phosphorus concentration were reduced significantly in rats given 10 mg/kg Cl2MDP compared to controls. Bone magnesium concentration was significantly elevated in rats given 10 mg/kg Cl2MDP. Serum calcium and phosphorus concentration were lower in Cl2MDP-treated rats. These results suggest that Cl2MDP is capable of altering bone remodeling, enzyme activity and mineral content, without significantly altering bone cell morphology, independent of the effects of parathyroid hormone, calcitonin, and dietary calcium.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-5604
    Keywords: gallium nitrate ; humoral hypercalcemia of malignancy ; nude mouse ; parathyroid hormone-related protein ; bone histomorphometry ; ultrastructure ; osteoclasts ; osteoblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hypercalcemic nude mice bearing a canine adenocarcinoma (CAC-8) model of humoral hypercalcemia of malignancy (HHM) were treated daily with gallium nitrate (60 mg/kg elemental gallium subcutaneously on day 0 followed by 20 mg/kg day for four days. Concentrations of gallium in bone were undetectable (〈0.00005 µg/g bone) in vehicle-treated mice but markedly elevated in gallium-treated mice (〉235 ± 6 µg/g bone). Gallium nitrate significantly decreased serum calcium and urinary calcium excretion in tumor-bearing mice compared with vehicle-treated controls. Histomorphometric evaluation of lumbar vertebrae revealed a significant decrease in the number of osteoclasts/mm trabecular bone in gallium-treated tumor-bearing mice compared with controls. Osteoclasts from tumor-bearing mice treated with gallium nitrate were significantly decreased in size, had reduced tartrate-resistant acid phosphatase staining intensity and ultrastructurally had fewer intracytoplasmic vesicles compared with vehicle-treated controls. Osteoclasts in gallium-treated mice were small and flattened with poorly developed cytoplasmic organelles. The findings of this investigation indicated that gallium nitrate reduced serum calcium in an animal model of HHM by inhibiting osteoclastic bone resorption.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-5604
    Keywords: PTHrP ; mammary gland ; lactation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mammary cells were isolated from lactating cows at 1 to 6 weeks after calving and evaluated for their ability to secrete PTHrP in vitro. The tissue was enzymatically digested to release glandular acini. The digested acini were cultured on thin (1.0 mm) or thick (2.5 mm) layers of collagen. The cultures containing thick collagen were detached and allowed to contract on day 6. The culture medium consisted of M199 with prolation (8 µg/ml), insulin (5 µg/ml), cortisol (5 µg/ml), and fetal bovine serum (15%). PTHrP production was measured by N-terminal RIA and bioassay (stimulation of adenylate cyclase in the ROS 17/2.8 cell line). Medium was collected at 2-day intervals for 14 days. The cells reached confluence at 4–6 days. PTHrP production was low at day 2 (〈0.5 ng/ml), but increased to peak production (2–4 ng/ml) at approximately day 6–8 of culture and remained constant until day 14. Immunoreactive and bioactive PTHrP levels in the culture medium correlated well. The cultures produced high levels of lactoferrin (500 to 3000 ng/ml) and low levels of αs1-casein (14 to 77 ng/ml). Prolactin stimulated PTHrP production approximately 50% on days 6–14. PTHrP production was increased approximately 100% by treatment with EGF (10 ng/ml) for 2 to 4 days. Histologic evaluation of cultures on thick, contracted collagen revealed an inner layer of epithelial cells with and an outer layer of collagen containing stromal cells. These data demonstrated that mammary cells from lactating cows produced and secreted PTHrP in vitro in a regulated manner.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-5604
    Keywords: parathyroid hormone-related protein ; PTHrP ; keratinocyte ; hypercalcemia ; squamous cell carcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Production of parathyroid hormone-related protein (PTHrP) by normal and neoplastic keratinocytes was compared in vitro to determine if the malignant phenotype alters the regulation of PTHrP expression and secretion. Three cell types consisted of normal human foreskin keratinocytes (NHFK), a well differentiated canine squamous carcinoma cell line (SCC 2/88), and a poorly differentiated human squamous carcinoma cell line (A253). The cells were grown in monolayers and on substrates (artificial dermis or collagen) to induce 3-dimensional layering of the cells and to permit medium collection from the basal and apical regions of the cells. Secretion of PTHrP was measured by N-terminal radioimmunoassay and mRNA production was measured by RNase protection assay. Secretion and mRNA production of PTHrP by NHFK and SCC 2/88 cells in monolayer culture was maximal at confluence (1–5 ng/ml) and decreased thereafter. In contrast, A253 cells continued to produce PTHrP after confluence in monolayer cultures. NHFK, SCC 2/88, and A253 cells in 3-dimensional, multilayered cultures produced high levels of PTHrP after confluence. Secretion of PTHrP was greatest from the basal cells compared to the apical cells of the cultures. PTHrP secretion was inhibited by monensin (1 µM). Transforming growth factor-β (1 to 5 ng/ml) increased PTHrP mRNA in NHFK at 6 hours and in SCC 2/88 cells at 1-24 hours. These data indicate that PTHrP is produced preferentially by proliferating keratinocytes and regulation of PTHrP production is different in normal keratinocytes compared to squamous carcinoma cells.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 90 (1968), S. 495-506 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Kittens with an immature skeleton fed exclusively a calcium-deficient beef heart diet for 1 to 14 weeks developed hypocalcemia, parathyroid hyperplasia, and generalized osteitis fibrosa. Initial ultrastructural changes in the stimulated parathyroid glands were observed after 1 week and consisted of increased cytoplasmic volume, aggregation of the granular endoplasmic reticulum, and enlargement of the Golgi apparatus associated with increased numbers of prosecretory granules. After 3 weeks, chief cell hyperplasia was first observed and the numbers of mature secretory granules were greatly reduced. The hyperactive chief cells remained degranulated until the termination of the experiment. Stimulated chief cells accumulated glycogen in excess of controls and contiguous chief cells had intricately interdigitated plasma membranes. The parathyroid glands of experimental cats after being fed the low calcium diet for 14 weeks contained primarily hyperactive and vacuolated light chief cells with an occasional transitional water-clear cell.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 171 (1971), S. 329-345 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The three types of bone cells in the nasal turbinates had characteristic ultrastructural features. Osteoblasts were located in areas of new bone formation and had abundant endoplasmic reticulum, prominent Golgi apparatuses, numerous vesicles, and cytoplasmic processes that penetrated the adjacent osteoid. Osteocytes had variable ultrastructural characteristics. The predominant cell filled the lacuna, had few organelles, smooth plasma membranes, and was interpreted to be a mature resting osteocyte. Some osteocytes appeared to be transitional between osteoblasts and mature osteocytes. Evidence of matrix formation was seen near osteocytes with well developed organelles, whereas osteocytes with swollen mitochondria, dense bodies and irregular plasma membranes appeared to be involved with resorption of bone. Multinucleated osteo-clasts contained numerous mitochondria and had crystals or unmineralized collagen fibrils between folds and within vacuoles of the cytoplasmic projections forming the brush border.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The microscopic anatomy of the atrioventricular node, bundle of His, both bundle branches and surrounding fibrous cardiac skeleton was studied in 40 large breed dogs of various ages. In the AV conduction system of all dogs over five years of age there was an increase of fibrous connective tissue, an infiltration of adipose tissue, loss of conduction fibers and focal fibrosis extending from the central fibrous body.Fibrosis was seen in the summit of the interventricular septum posterior to the AV node in dogs of all ages. Chondroid metaplasia was consistently observed in the central fibrous body and the root of the aorta in large breed dogs, including ten Doberman Pinschers of all ages. This metaplasia varied from a few chondroblasts and chondrocytes to mature chondrocytes with mineralization. Bone formation was seen in eight dogs. These changes appeared in close approximation to the cardiac conduction system above the bundle of His. No degenerative changes were seen in the AV bundle. Approximately one-half of the large breed dogs five years of age and older had thickened medial and intima proliferation in the small coronary arterioles supplying the AV node. The results of this study suggest that the presence of cartilage and bone in the central fibrous body is a normal occurrence in large breed dogs at all ages.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the parathyroid glands of normal rapidly growing cats (9-22 weeks of age) was described and compared with the findings reported in other species. The predominating active chief cells were relatively electron-dense and contained well developed organelles and frequent secretory granules. Inactive chief cells were slightly larger and had a more electron-transparent cytoplasm. Cytoplasmic organelles were less well developed and secretory granules were less frequent than in the active chief cells. Oxyphil cells or transitional forms were not identified in the parathyroid glands of kittens. Occasional cilia were observed in chief cells. They arose near centrioles and protruded from the plasma membrane into the intercellular space.
    Type of Medium: Electronic Resource
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