Polypyrrole-glucose oxidase biosensor. Effect of enzyme encapsulation in multilamellar vesicles on analytical properties.

In this paper, we present the analytical properties of a new type of polypyrrole-based, enzymatic amperometric biosensor. It is produced by encapsulating the enzyme, glucose oxidase (GOx), into onion-type multilamellar vesicles (MLV). We compare its properties to those of a classical GOx-polypyrrole biosensor.

Interaction of doxorubicin with ATP: quantification of complexes and effect on its diffusion into DNA-loaded liposomes--implication for ATP-driven transport studies.

Doxorubicin, a drug largely used in chemotherapy, is transported by P-glycoprotein, a protein involved in the multidrug-resistance phenotype. Taking advantage of the doxorubicin fluorescence quenching upon interaction with DNA, a sensitive assay of this active transport can be carried out: quantitative in vitro studies could be achieved with DNA-loaded proteoliposomes, after correction for the doxorubicin passive diffusion through phospholipids. In this paper, we describe experimental conditions that will be relevant to P-glycoprotein studies.

Cooperative P-glycoprotein mediated daunorubicin transport into DNA-loaded plasma membrane vesicles.

Most of the multidrug resistant human tumor cell lines overexpress the MDR1 gene product P-glycoprotein (P-gp) which is believed to function as an energy-dependent drug efflux pump. Here we describe a novel method that allows the kinetic characterization of P-gp-mediated active drug transport. This method is based on the fluorescence quenching of anthracyclines transported into DNA-loaded plasma membrane vesicles.

Plasticity of astroglial glutamate and gamma-aminobutyric acid uptake in cell cultures derived from postnatal mouse cerebellum.

The plasticity of astroglial glutamate and gamma-aminobutyric acid (GABA) uptakes was investigated using mouse cerebellar cell cultures. The influence of external factors, such as different sera and/or the presence of neurons, was examined. Control autoradiography experiments showed that after short-term exposure to radioactive amino acids, granule cells took up neither glutamate nor GABA, and beta-alanine predominantly inhibited astroglial GABA uptake.

Neurotransmitters and stimulation of fluid reabsorption in migratory locust rectal cells.

Several biogenic amines enhance fluid reabsorption and the accumulation of cyclic adenosine-monophosphate (cAMP) in the rectum of the migratory locust but only 5-hydroxytryptamine (5-HT) acts in a dose-dependent manner at low concentrations (between 10(-8) and 5.10(-7) M). Cyclic AMP is a second messenger of 5-HT, and its actions on fluid reabsorption are calcium-dependent.