Cells exhibiting the multidrug resistance (MDR) phenotype demonstrate a decreased intracellular drug accumulation due to an active outward transport and decreased intracellular flux. This study demonstrates the inhibition of MDR in mussel (Mytilus edulis) embryos and larvae based on a simple bioassay. The development of embryos was assessed and abnormalities identified at key stages of development, including gastrulation, trochophore and prodissoconch stages. The incidence of developmental abnormalities was significantly increased in the presence of vinblastine, MMS, chloroquine, mitomycin-C, cadmium chloride and colchicine, compared to clean seawater. Consistently, there was a further increase in the number and severity of deformities observed when each toxin was added in the presence of verapamil. Larval growth was also significantly impaired in the presence of verapamil. Increased accumulation of fluorescent MDR dyes, such as rhodamine B, has been measured and shown to be verapamil sensitive. This bioassay encompasses a period of intense cellular activity during which the impairment of a number of critical processes results in abnormal growth and development.

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PubMedDate not supplied

Immunomagnetic isolation of islets from the rat pancreas.

Islets were selectively isolated from rat pancreatic digests using magnetic microspheres coated with anti-islet monoclonal antibodies. The isolation process was optimized as a function of bead concentration and time of incubation with the tissue digest. Apparent and normalized islet yields of 92 +/- 6% and 81 +/- 7%, respectively, were obtained by incubating the digests with 10(7) beads/mL for 40 min followed by isolation of the bead-coated islets under a magnetic field. While some fragmentation occurred, the isolation process did not alter islet functionality as demonstrated by an insulin secretion response to glucose stimulation equivalent to that of handpicked controls. The technique is fast, reproducible, and potentially scaleable to larger pancreases as a secondary purification step.

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