Abstract: The present invention provides a system and method for expressing a functional ABC (ATP-binding cassette) transporter in a host cell. A system comprises two or more expression vectors each comprising a nucleic acid molecule encoding one or more domains of the ABCR transporter gene and a means for expressing the nucleic acid molecule. Each expression vector of the system includes a nucleic acid molecule that encodes a domain that is functionally complementary to domains contained in the other expression vectors of the system but when taken together comprise the full ABCR transporter gene. Co-transfection of the expression vectors into a host cell provides co-expression of each of the domains of the protein which assemble to form an ABC transporter protein having functional characteristics of the full-length protein.

Abstract: Colloidal sized particles comprising metal particle coated with a water soluble polysaccharide derivative. The derivative is such that when it is not coating the metal, it has at least one, and preferably a number, of pendant functional groups each of which has a positive charge in aqueous solution. The metal is preferably selected from the group consisting of gold, platinum, and silver, whereas the polysaccharide may usefully be selected from the group consisting of dextran and mannan. The particles can be used as markers for biologically active molecules, or for separating different types of such molecules.

Abstract: The invention relates to colloidal sized particles composed of magnetic iron oxide (Fe.sub.3 O.sub.4) coated with a polysaccharide, preferably dextran, or a derivative thereof having pendant functional groups. The particles have a magnetic moment, are electron dense, and are stable and non-aggregating under physiological conditions. They can be covalently bonded to antibodies, enzymes and other biological molecules and used to label and separate cells, cellular membranes and other biological particles and molecules by means of a magnetic field.

Abstract: Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing.

Abstract: Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing.

Abstract: Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing.

Abstract: Biocompatible polymeric microspheres having an average diameter below about 3 microns and having a density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.

Abstract: Biocompatible polymeric microspheres having an average diameter below about 3 microns and having density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.