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  • 1
    Electronic Resource
    Electronic Resource
    Inhibition of Multidrug Resistance-Associated Protein (MRP) Functional Activity with Pluronic Block Copolymers (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 396-401 
    Details
    ISSN: 1573-904X
    Keywords: block copolymer ; cancer ; multidrug resistance ; Pluronic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Using monolayers of human pancreatic adenocarcinoma cells (Panc-1) that express multidrug resistance-associated protein (MRP), the present work investigates the effects of Pluronic block copolymers on the functional activity of MRP. Methods. The studies examined the accumulation and efflux of the MRP selective probe fluorescein (FLU) in Panc-1 cell monolayers with and without Pluronic P85 (P85), Pluronic L81 (L81) and Pluronic F108 (F108). Results. Treatment of Panc-1 cells with P85 resulted in concentration-dependent increases in FLU accumulation and elimination of FLU sequestration in vesicular compartments in these cells. The effects of P85 were selective for FLU in the Panc-1 cell monolayers. Inhibition of MRP-mediated transport was dependent on the composition of Pluronic block copolymer: the more hydrophobic copolymer had the greater effect on FLU uptake in Panc-1 monolayers (L81 〉 P85 〉 F108). Conclusions. This paper demonstrates for the first time that Pluronic block copolymers inhibit multidrug resistance-associated protein (MRP). The similarities in the effects of Pluronic block copolymers on MRP and P-glycoprotein drug efflux systems suggest that a single unifying mechanism may explain the inhibition observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018873702411
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of Pluronic Block Copolymers on Drug Absorption in Caco-2 Cell Monolayers (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 850-855 
    Details
    ISSN: 1573-904X
    Keywords: block copolymer ; intestinal delivery ; drug ; micelles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present work characterizes the effects of Pluronic copolymers on the transport of a P-gp-dependent probe, rhodamine 123 (R123) in Caco-2 cell monolayers. Methods. The accumulation and efflux studies were performed on the confluent Caco-2 monolayers using fluorescent probes with and without Pluronic copolymers. Results. At concentrations below the critical micelle concentration single chains ("unimers”) of Pluronic P85 enhanced the accumulation and inhibited the efflux of R123 in Caco-2 monolayers. The transport of the P-gp-independent probe, rhodamine 110 was not altered under these conditions. In contrast the micelles increased R123 accumulation to a much lower extent when compared to the unimers and enhanced R123 efflux in Caco-2 monolayers. Conclusions. Pluronic P85 unimers increase accumulation of a P-gp-dependent drug in Caco-2 monolayers through inhibition of the P-gp efflux system. The mechanism of the micelle effect is not known, however, it is very similar to the micelle effects in BBMEC. This has been previously shown to involve vesicular transport of the micelle-incorporated drug. The study suggests that Pluronic copolymers can be useful in increasing oral absorption of select drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011964213024
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  • 3
    Electronic Resource
    Electronic Resource
    Composition homogeniety of alternating copolymers and their propagation mechanism (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1773-1775 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150725
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of ZnCl2 on the rate of thermal decomposition of azobisisobutyronitrile (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1777-1778 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150726
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  • 5
    Electronic Resource
    Electronic Resource
    Nature of gel effect in radical polymerization (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 613-616 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170230
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  • 6
    Electronic Resource
    Electronic Resource
    Radiation-induced grafting polymerization by the anionic mechanism (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1255-1266 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-induced grafting polymerization of phenylacetylene and 2-methyl-5-vinylpyridine (2M-5VPy) onto low-density polyethylene has been investigated under strict identical conditions, using crude and thoroughly dried monomers. In the case of thoroughly dried monomers, the radiation-induced grafting is performed by the combined (radical + anionic) mechanism. The kinetics of radical and anionic grafting of 2M-5VPy are investigated in detail. The activation energies are 4.8 ± 0.3 and -2.7 ± 0.3 kcal/mole for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to the dose rate to the 0.47 ± 0.03 and 0.92 ± 0.03 power for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to monomer concentration to the 1.55 ± 0.05 and 2.1 ± 0.05 power for the radical and anionic grafting, respectively. These data conform to the contribution of the anionic mechanism in a thoroughly dried system. The mechanism of radiation-induced anionic grafting is discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170501
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanism of alternating copolymerization of methyl methacrylate with styrene in the presence of diethylaluminum chloride (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 619-638 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study of the propagation mechanism of the alternating copolymerization of styrene (St) with methyl methacrylate (MMA) in the presence of a complexing agent (diethylaluminum chloride, DEAC) in bulk and in tetrachloroethylene solutions at a molar ratio DEAC/MMA = 0.5 has been carried out. It has been shown that the copolymerization is a chain radical process characterized by a short active-center lifetime, bimolecular termination, and high rate of chain transfer to the complexed MMA. A kinetic scheme has been proposed for the propagation mechanism of alternating copolymerization in the presence of a complexing agent not requiring independent measurements of the equilibrium constant of complexation. It has been found that spontaneous and UV-initiated copolymerizations in the system have different mechanisms of initiation and a common mechanism of propagation. The propagation proceeds by addition of single monomers as well as donor-acceptor complexes of the comonomers to the propagation radicals, with the first mechanism being predominant. Inclusion of the monomers in the complex leads to an increase of the St reactivity and to a decrease of the MMA reactivity in propagation to the corresponding macroradicals in comparison with the reactivity of the free monomers. A number of kinetic and statistical parameters of the propagation reaction have been calculated.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200304
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  • 8
    Electronic Resource
    Electronic Resource
    Physicomechanical properties of grafted polymers obtained by radiation-induced polymerization by radical and ionic mechanisms (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 1825-1828 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-induced grafting of acrylonitrile, 4-vinylpyridine, and styrene was carried out by both radical and ionic mechanisms. Grafted polymers with equal percentages of graft were obtained by the radical and ionic propagation of the grafted chains. The molecular weight of homopolymers has been determined. The thermomechanical properties of the graft polymers were investigated. The yield temperatures for the graft polymers obtained by ionic propagation of the grafted chains is higher than that of graft polymers obtained by a radical mechanism. This is attributed to the higher molecular weight of the grafted chains obtained by the radiation-induced grafting by the ionic mechanism. The radiation-induced grafting of polyacrylonitrile increases significantly the thermal stability of polyethylene. The differential thermal analysis shows no marked differences in properties of the polymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.170140802
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanism of alternating copolymerization of polar and hydrocarbon polymers (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 2463-2487 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical copolymerization of butyl methacrylate with 2,3-dimethylbutadiene in the presence of Al(C2H5)2Cl or ZnCl2 results in alternating copolymers. The nature of active centers and the mechanism of polymerization in these systems have been studied by means of ESR measurements in combination with calorimetry at low temperatures. The active centers are monoradicals propagating by alternative addition of single monomer molecules; thus the reaction can be described in terms of a conventional kinetic scheme of radical additional polymerization. Participation of binary donor - acceptor complexes of the monomers in the reaction has not been confirmed. Similar conclusions have been drawn for the other alternating system studied, maleic anhydride-2,3-dimethylbutadiene. The feasibility of formation of alternating copolymers in the studied systems by the conventional mechanism of binary radical copolymerization has been confirmed by qualitative quantum-chemical treatment of the propagation reactions with due account to the donor-acceptor interactions in the transition state.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170111005
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  • 10
    Electronic Resource
    Electronic Resource
    Formation of crystalline polyelectrolytic complexes on matrix polymerization (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 2351-2356 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zwitterionic matrix stepwise polymerization of 4-vinylpyridine (VP) using isotactic poly(acrylic acid) (i-PAA) as a template results in formation of crystalline polycomplexes consisting of i-PAA and of ionene (I): Depending on the concentration of VP and i-PAA, the two types of crystalline polycomplexes can be prepared. The complex containing long ionene sequences with n ≫ 2 is formed when [VP]0 = [i-PAA]0 ≥ 0.05M. At [VP]0 = [i-PAA]0 ≤ 0.01M, the complex formed evidently contains the ionene dimer (n = 2). The x-ray structures of the crystalline complexes are identical with those obtained by mixing of i-PAA and the corresponding dimer and polymer presynthesized in the absence of the template. The matrix polymerization of VP in the presence of syndiotactic and atactic PAA at the same conditions results in formation of amorphous polycomplexes.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.170141002
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