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  • 1980-1984  (4)
  • 1950-1954
  • 1920-1924
  • Cell & Developmental Biology  (2)
  • Chemical Engineering  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 810-815 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: In a previous paper, a two-parameter model was described that could be used to predict the hydrogen bond enthalpy of formation between two compounds forming a single hydrogen bond. This paper describes the extension of the use of the two parameters for solvents and polymeric resins in another mathematical model that involves four terms that determine the “hydrogen bonding potential” (HBP) interaction between a resin and a given solvent. Each solvent and each resin can be assigned a donating and accepting parameter (relative to hydrogen bond formation) that combine to yield a numeric value for HBP. A negative HBP value is associated with favorable hydrogen bonding between a resin and a solvent which should correspond to a situation in which solution formation is favorable. A positive HBP value indicates unfavorable interaction which discourages solution formation. Thus, HBP becomes a predictive model of solubilities. Numerical data are presented for four resins and 26 solvents that correlate well with observed solubility behavior. Using this model, it is also possible to construct “solubility maps,” and these are also discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 298-308 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Platelet-derived growth factor (PDGF) is a potent mitogen for cultured cells of mesenchymal origin. Known sources of PDGF or PDGF-like protein are blood platelets, several transformed cell lines, and cultured endothelial cells (EC). We have examined the regulation of production of a PDGF-like protein in cultures of bovine aortic EC using a specific radioreceptor assay for PDGF. EC constitutively secreted PDGF-like protein into serum-containing or serum-free medium. The rate of production of PDGF-like protein was constant for at least 3 weeks and was not due to release of an internal store, since cell lysis by repeated freeze/thaw cycles did not relase significant amounts of the protein. Synthesis of PDGF-like protein was sensitive to changes in the pH of the media and was maximal at pH 8.5. Production of PDGF-like protein was independent of EC growth rate: rapidly dividing cells and confluent, quiescent cells produced equal amounts per cell. However, sparse, quiescent EC produced more PDGF-like protein per cell than did confluent, quiescent cells. Several phorbol esters stimulated production of PDGF-like protein. At a concentration of 10-6 M, a twofold stimulation was observed upon addition of the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) and nearly a fourfold stimulation upon addition of the nonpromoting analog, methyl TPA. Incubation of EC with endotoxin (10 μ/ml) resulted in a twofold stimulation of PDGF-like protein production. In all experiments with endotoxin and phorbol esters, an increase in the production of PDGF-like protein was accompanied by morphological changes in the EC cultures. The cells appeared elongated and fibroblastic and exhibited low viability. A mathematical model was developed in which PDGF-like protein production was shown to consist of two separate components - production at a constant rate by healthy cells and a large burst of synthesis and secretion by dying cells. These results suggest that injurious agents may be capable of stimulating production of a growth factor by the endothelium.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 339-345 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured bovine aortic endothelial cells (BAEC) can be maintained at saturation density for several weeks in the absence of serum. These cells retain viability and normal culture morphology, and continuously produce a growth factor for mesenchymally derived cells-the endothelium-derived growth factor (EDGF). The amount and specific activity of EDGF that is produced by BAEC under serum-free conditions remains constant for weeks. The levels of EDGF produced under these serum-free conditions is equivalent to levels produced in medium containing 5% plasma-derived serum. EDGF has been found to be trypsin sensitive, acetone and ammonium sulfate precipitable, and resistant to heat and sodium dodecyl sulfate treatment. Gel filtration on Sephacryl S-200 in the presence of formic acid (1%) yields two major peaks of activity corresponding to proteins of apparent molecular weights of approximately 24,000 and 14,000 daltons. This chromatographic step affords a ten-to 12-fold purification with a combined recovery of greater than 85%. Unlike brain or pituitary fibroblast growth factor, EDGF activity is destroyed by dithiothreitol or periodic acid. EDGF is not a somatomedin since it exhibits no detectable sulfation activity in a porcine cartilage assay. EDGF is not inhibited by antiserum to epidermal growth factor and is capable of stimulating DNA synthesis in a 3T3 variant cell line that is nonresponsive to and lacks receptors for epidermal growth factor. The majority of EDGF activity does not behave like the platelet-derived growth factor during ion exchange chromatography. Antisera prepared in rabbits and in mice to human platelet-derived growth factor has little effect on bivine or human EDGF activity. These biochemical and immunological properties of EDGF indicate that it is distinct from several other well-characterized polypeptide growth factors.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 4 (1982), S. 124-127 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Field observations of lubricant type and level control are presented with the intent of promoting laboratory routes to developing better rigid formulations. Calcium stearate is identified as a gelation promoter. PE wax is described as a very effective gelation retarder. POPE is an effective slip agent, ineffective retarder, and slight promoter. It is obvious that more understanding of the functions of lubricants is needed to permit on-line formulation adjustment.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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