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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of endogenous hormones and receptors in bone tissue: An immunocytological approach in frozen samples
    Amsterdam : Elsevier
    Micron 25 (1994), S. 15-27 
    Details
    ISSN: 0968-4328
    Keywords: Immunocytology ; bone tissue ; calcitonin ; cryoultramicrotomy ; growth hormone ; osteoblast ; parathyroid hormone ; receptors ; steroid hormones ; vitamin D
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0968-4328(94)90052-3
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  • 2
    Electronic Resource
    Electronic Resource
    Evidence for a direct effect of growth hormone on osteoblasts (1993)
    Springer
    Cell & tissue research 273 (1993), S. 279-286 
    Details
    ISSN: 1432-0878
    Keywords: Osteoblasts ; Growth hormone ; Growth hormone-receptor ; Alkaline phosphatase ; Immunocytology ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In order to determine whether growth hormone (GH) exerts a direct effect on osteoblasts, in vitro and in vivo immunocytological studies were carried out on newborn rat calvaria and a clonal osteoblast-like cell line (MC3T3-E1) isolated from newborn mouse calvaria. After exposure to human growth hormone (hGH) or 1,25 dihydroxyvitamin D3 (1,25(OH)2D3), a significant increase in alkaline phosphatase activity was observed in MC3T3-E1 cells. Simultaneous exposure of MC3T3-E1 cells to hGH and 10 nM 1,25(OH)2D3 showed a synergistic effect of the two hormones on this activity. The optimal dose of hGH was 0.1 nM. An immunocytological procedure was performed on ultrathin frozen sections from 7-day-old rat calvaria and MC3T3-E1 cells cultured with hGH. GH-like immunoreactivity was observed in both cases. In calvaria, endogenous GH-like immunoreactivity was localized at the same ultrastructural level (plasma membrane, cytoplasmic and nuclear matrices) as exogenous GH-like immunoreactivity in MC3T3-E1 cells. Following the initial step of binding to the plasma membrane, GH may be internalized in the cytoplasmic matrix and nucleus. In situ hybridization revealed the presence of mRNA coding for GH receptor in calvaria cells. The density of these receptors seemed to be lower in osteoblasts than in hepatocytes. In MC3T3-E1 cells, hGH induced a dose-dependent secretion of insulin-like growth factor 1. In conclusion, these results indicate that GH may act directly on osteoblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312829
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  • 3
    Electronic Resource
    Electronic Resource
    Liquid transport through membranes prepared by grafting of polar monomers onto poly(tetrafluoroethylene) films. I. Some fractionations of liquid mixtures by pervaporation (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1061-1076 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The separation of various liquid mixtures including systems of chloroform-hydrocarbons or ethyl ether, water-alcohols and water-nucleophilic organic solvents have been investigated by the pervaporation technique. Membranes were obtained by grafting Lewis base onto poly(tetrafluoroethylene) (PTFE) films. The PTFE backbone has been chosen for its mechanical and chemical resistance. N-Vinylpyrrolidone and 4-vinylpyridine were selected because of their great affinity for the electrophilic compounds. In all cases, the compound which has the greatest affinity for the membrane pervaporates selectively through modified PTFE films. Selectivity and rates were studied. It is concluded that because selectivity is very important, total separation of different mixtures is possible at a good yield, with a faster rate when the temperature is increased or the thickness of the membrane is decreased.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160502
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  • 4
    Electronic Resource
    Electronic Resource
    Liquid transport through membranes prepared by grafting of polar monomers onto poly(tetrafluoroethylene) films. II. Some factors determining pervaporation rate and selectivity (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 351-364 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of some factors including temperature, pressure, film thickness, and grafting ratio on the fractionation of binary liquid mixtures has been investigated by pervaporation through poly(tetrafluoroethylene) films grafted with N-vinylpyrrolidone or 4-vinylpyridine. The purpose was to estimate the best conditions in which the pervaporation process must be carried out. It was concluded that the pervaporation rate is increased at roughly constant selectivity when the temperature of the liquid charge is higher or when the downstream vapor pressure or the film thickness are decreased. A pressure higher than 1 atmosphere above the liquid does not increase the rate. When the grafting ratio is increased, the rate shows a maximum, and for particular conditions, the selectivity becomes much higher.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180204
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  • 5
    Electronic Resource
    Electronic Resource
    Gas sorption and transport in poly(phenylene oxide) and comparisons with other glassy polymers (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 2997-3005 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The sorption and transport of several gases in poly(phenylene oxide) were measured at 35°C, and the results have been analyzed in terms of the dual sorption/mobility models which have been successfully employed for this purpose for other glassy polymers. Both the extent of sorption and rate of permeation of gases are quite large for poly(phenylene oxide) compared to other glassy polymers with rigid chain backbones. It is shown that the high extent of sorption is owing to the high glass transition temperature of this polymer, but this is not a significant factor in its high permeability to gases. The latter stems from large diffusion coefficients. It is shown that the capacity of the Langmuir mode of sorption inherent to glassy polymers is related to the value of the glass transition temperature in a general way for a wide variety of polymers. Observations about the diffusion coefficients for numerous gas-polymer pairs are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270823
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  • 6
    Electronic Resource
    Electronic Resource
    Pervaporation membranes prepared by radiochemical grafting of N-vinylpyrrolidone onto films (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2397-2407 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pervaporation performances of membranes obtained by radiation grafting of N-vinylpyrrolidone onto poly(tetrafluoroethylene), polyethylene, polybutene, and poly(dimethylsiloxane) films were studied using a water-dioxane azeotropic mixture. The influence of the following parameters was examined: grafting ratios, radiation dose rates, nature of the base films, poly(tetrafluoroethylene) film-making methods, and structural transition. An attempt has been made to interpret the results in terms of variations in the number, size, and density of the grafted domains which form the diffusion paths for the permeating molecules. Based on this interpretation, a general rule is proposed for selecting adpated methods to prepare efficient pervaporation membranes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230817
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  • 7
    Electronic Resource
    Electronic Resource
    Liquid transport through membranes prepared by grafting of polar monomers onto poly(tetrafluoroethylene) films. III. Steady-state distribution in membrane during pervaporation (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 365-378 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Steady-state concentration and composition gradients of pervaporating liquids inside the membranes were measured using stacks of membranes. The experimental results on pure components agree well with a simple mechanism of diffusion down a chemical potential gradient in a nonporous membrane. For mixtures, concentration gradients are similar to those obtained for pure liquids, and composition distribution shows that the selection between the two species does not take place at a given interface in the membrane but is progressive along the diffusional paths through the membrane. Data are also listed to show that solubility and diffusivity enhancements occur for components which are hydrogen bonded with the basic groups of the membrance.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180205
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and morphology of poly(tetrafluoroethylene)-poly(N-vinylpyrrolidone) copolymer membranes (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 771-780 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The structure and morphology of poly(tetrafluoroethylene)-poly(N-vinylpyrrolidone) (PTFE-PVP) copolymer membranes prepared by direct radiation grafting were studied by using differential scanning calorimetry, x-ray diffraction, and scanning electron microscopy. The granulometry of the base emulsion used in PTFE film forming did not have any influence on the mechanism of radiochemical grafting. Moreover, it is proposed that the size of base grains induces morphologies of grafted membranes which differ markedly from each other. The results are analyzed on the assumption that grafted chains of PVP are formed between the base grains of PTFE and gradually move inward toward the crystalline zones. For a given grafting ratio, the space of distribution of grafted chains inside the PTFE matrix depends on the size of PTFE base grains. A correlation between morphologies of membranes and water permeability of copolymer membranes is indicated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240314
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