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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Non-Ionic Surfactants on the Formation of DNA/Emulsion Complexes and Emulsion-Mediated Gene Transfer (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1642-1646 
    Details
    ISSN: 1573-904X
    Keywords: emulsions ; gene transfer ; transfection ; gene therapy ; non-ionic surfactant ; cationic lipid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the structure-function relationship of non-ionic surfactants in emulsion-mediated gene delivery. Methods. Four different types of non-ionic surfactants including Tween, Span, Brij and pluronic copolymers were used as co-emulsifiers for preparation of emulsions composed of Castor oil, dioleoylphosphatidylethanolamine (DOPE) and 3β[N-(N′, N′-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol). The effect of different surfactants on the formation of DNA/emulsion complexes and transfection activity were analyzed using plasmid DNA containing luciferase cDNA as a reporter gene. Results. Non-ionic surfactants containing branched polyoxyethylene chains as the hydrophilic head group were more effective in preventing the formation of large DNA/emulsion complexes than those containing one or no polyoxyethylene chain. All emulsion formulations except those containing Brij 700 exhibited high activity in transfecting mouse BL-6 cells in the absence of serum. In the presence of serum, however, transfection activity of each formulation varied significantly. Emulsions containing Tween, Brij 72, pluronic F68 and F127 demonstrated increased activity in transfecting cells in the presence of 20% serum. In contrast to emulsions containing Span, long chain polyoxyethylene of Brij showed decreased transfection activity. The particle size of the DNA/emulsion complexes and their ability to transfect cells are dependent on the concentration of non-ionic surfactant in the formulation. Conclusions. The structure of the hydrophilic head group of the non-ionic surfactants in the emulsion is important in determining how DNA molecules interact with emulsions and the extent to which DNA is transferred inside the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016480421204
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    New Cationic Lipid Formulations for Gene Transfer (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1856-1860 
    Details
    ISSN: 1573-904X
    Keywords: gene transfer ; gene therapy ; cationic lipid ; transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop appropriate dosage forms of DNA for gene delivery. Methods. 3β[N-(N′, N′ dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) was mixed either with Tween 80 alone, or with additional lipid components including castor oil and phosphatidylcholine (PC) or dioleoylphosphatidylethanolamine (DOPE) to make different lipid formulations. The particle size and the physical stability of the formulations upon mixing with plasmid DNA containing the luciferase cDNA were examined using laser light scattering measurement. The transfection activity of the DNA/lipid complexes was tested in presence or absence of serum using a cell culture system. Results. We demonstrated that many favorable properties as a gene carrier could be achieved by formulating DNA into new dosage forms using Tween 80 as the major emulsifier. Compared to the cationic liposomes, these new formulations transfected different cell lines with an equivalent or higher efficiency. Not only are they resistant to serum, but also form stable DNA complexes which could be stored for longer periods of time without losing transfection activity. Conclusions. Cationic lipids formulated into different lipid formulations using Tween 80 as a surfactant appeared to have more favorable physical and biological activities than traditional cationic liposomes as a carrier for gene delivery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016041326636
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Accelerated calcium ion uptake in murine thymocytes induced by concanavalin A (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 93 (1977), S. 153-160 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism of enhancement of Ca2+ uptake by the T cell mitogen concanavalin A (Con A) was studied in murine thymocytes. Native Con A enhanced the rate of Ca2+ uptake as much as 9-fold, an increase being observed within five minutes after Con A addition. The effect of Con A was reversed completely by α-methyl mannopyranoside (α-MM). Increased Ca2+ uptake was observed with increasing concentrations of Con A, between 2 and 400 μg/ml, indicating that the stimulation of Ca2+ uptake is not restricted to mitogenic lectin concentrations (0.5-2 μg/ml). Succinyl Con A exhibits only a slight effect in the same concentration ranges as native Con A. Ca2+ uptake, both in the absence and presence of Con A, is strongly dependent on energy metabolism and is carrier mediated. The augmentation of Ca2+ uptake by native Con A is due to an enhanced Vmax. Uptake of the anion, CrO42-, by thymocytes, found to be a nonsaturable process, was also enhanced by Con A. The effect of Con A on CrO42- permeability appears to be independent of its effect on Ca2+ uptake.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040930119
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    Paper (German National Licenses)
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