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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 738-739 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1092-1104 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present an approach for determining in vitro the means and distributions of a set of phenomenological parameters, including cell speed and persistence time, which can be used to evaluate the effect of isotropic variations in the extracellular environment on the motility of human tissue cells. Using time-lapse videomicroscopy and semi-automated image analysis, we tracked the paths traveled by slow-moving, isolated human vascular smooth muscle cells over 48 hours on surfaces of petri dishes coated with 10 μg/mL of the adhesive extracellular matrix proteins type IV collagen, fibronectin or laminin. By applying a persistent random walk model to experimental data for mean-squared displacement as a function of time for these cells, we rigorously distinguished individual cells with different motile characteristics not obvious based on qualitative comparisons between the structures of individual cell paths. We also positively identified the presence of immotile cells. Based on the behavior of 34 to 77 cells on each substrate, we found mean cell speeds and persistence times on the order of 10 micron/h and 3 hours, respectively, on all three ECM substrates, while the fraction of motile cells varied from 65% on laminin to 78% on collagen. On all three surfaces experimental number distributions of speed and persistence time could be described by normal and exponential waiting time distributions, respectively. Our approach provides a framework for addressing questions concerning the mechanistic relationship between cellular and environmental properties and cell motility.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1443-1453 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Expression of proteins in eucaryotic systems is often the only way to ensure the correct folding and processing necessary for protein function. Heterologous proteins, however, are commonly retained in the secretory pathway, so that secreted product yield is low despite a high level of transcription. A major limiting step in protein secretion is protein folding in the lumen of the endoplasmic reticulum. This process is assisted by accessory macromolecules resident in this compartment, including chaperones such as the hsp70 homologue binding protein (BiP). Although induction of foreign proteins in yeast initially elicits a transient increase in local chaperone concentration, long-term protein expression lowers both chaperone and secreted product. A mechanistic model that can account for the experimentally observed role of BiP in secretion and the effects of BiP overexpression on the secretory pathway is described here. The model predicts that equimolar synthesis of chaperone and foreign protein should optimize protein secretion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 459-465 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During inflammation, leukocytes cross the blood vessel wall and migrate to the inflammatory site in response to gradients of diffusible chemical attractants produced there. This directed migration response to a chemical gradient, termed chemotaxis, can be studied experimentally in the Millipore filter assay. We have applied a mathematical model to analyze cell population migration in the assay in terms of two parameters analogous to molecular transport coefficients. The random motility coefficient, μ, reflects the cell response to uniform concentrations of chemical attractant, while the chemotaxis coefficient, χ, reflects the response to a concentration gradient. We have measured μ and χ by comparing theoretical cell density profiles to those measured in the assay. Both parameters vary as a function of the attractant concentration; μ ranges from 10-10-10-9 cm2/s and χ ranges from 10-100 cm2/s.M for the attractant tested. These values agree with ones predicted from a priori theoretical relationships for μ and χ. Quantitation of the Millipore filter assay provides a framework for the quantitation of analogous cell transport systems such as a composite assay simulating cell migration across the vessel wall.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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