Abstract: A method is described to determine multidrug resistance in living cells by laser scanning confocal fluorescence microscopy of doxorubicin in sensitive and resistant tumor cells. The intracellular distribution of doxorubicin in K562 cells has been studied by laser scanning confocal fluorescence microscopy. A different fluorescence pattern has been observed in sensitive and resistant cells. An intense fluorescence signal is evident on the plasma membrane of K562R cells with multidrug resistance. The fluorescence imaging of the drug offers then a new method--non destructive--to discriminate between sensitive and resistant cells, with high potential in the diagnosis of resistance in tumors in vivo. The differences in the intracellular drug distribution, as seen by laser scanning confocal fluorescence microscopy, moreover offer new indications on the mode of action of the drug in the living cell.

Abstract: Toughenable polymer compositions cross-linkable thermally or by the effect of U.V. radiation are composed of:1) A polyphenylene ether (PPE) deriving from the (co)polymerization of one or more substituted phenols by oxidative coupling;2) At least one mono-unsaturated monomer compound able to (co)polymerize in the presence of radical initiators;3) Optionally, at least one polyunsaturated monomer compound able to (co)polymerize in the presence of radical initiators;4) At least one radical polymerization initiator;5) Possibly at least one (co)polymer with elastomeric characteristics;6) Usual additives, stabilizers, accelerators and flame retardant agents.Finished articles essentially composed of an intimately copenetrated polymer blend are obtained by thermal treatment or U.V. radiation of these compositions contained in suitable moulds either along or in combination with other reinforcement materials.