Cholecystokinin (CCK) is a gastrointestinal hormone that acts through a G protein-coupled receptor to stimulate pancreatic enzyme secretion. In this work, we demonstrate that CCK stimulation of dispersed pancreatic acini results in increased tyrosine phosphorylation of several cellular proteins. This is mediated via a calcium-dependent pathway, also activated by a phenethyl ester analogue of CC...

The biosynthesis of phosphatidylserine (PtdSer) by the serine base-exchange enzyme system, in Jurkat T-lymphocytes, was inhibited in intact cells maintained in low-Ca(2+)-containing buffer (< 10 microM-Ca2+) by using Ca2+ ionophores (A23187 or ionomycin). The rise in cytosolic Ca2+ concentration under these experimental conditions was only due to the release of Ca2+ from intracellular compartme...

Copper-ionophores that elevate intracellular bioavailable copper display significant therapeutic utility against prostate cancer cells in vitro and in TRAMP (Transgenic Adenocarcinoma of Mouse Prostate) mice. However, the pharmacological basis for their anticancer activity remains unclear, despite impending clinical trails. Herein we show that intracellular copper levels in prostate cancer, eva...

A new method, based on the ion-translocating properties of the ionophores nigericin and A23187, is described for loading large unilamellar vesicles (LUVs) with the drugs vincristine and ciprofloxacin. LUVs composed of distearoylphosphatidylcholine/cholesterol (DSPC/Chol) (55:45 mol/mol) or sphingomyelin (SPM)/Chol (55:45 mol/mol) exhibiting a transmembrane salt gradient (for example, internal s...

There is considerable interest in synthetic ionophores with high affinity and selectivity for Li(+). But so far, compounds that selectively bind Li(+) in the presence of other alkali and alkaline earth metal ions are rare and current approaches toward this goal are often accompanied with substantial synthetic efforts. Here we describe a trinuclear ruthenium metallamacrocyclic complex (1) that w...

To test the influence of the electrochemical ion gradient across mycoplasma membranes on the capacity of organisms to adhere to host cells, Mycoplasma gallisepticum cells were treated with valinomycin, carbonylcyanide m-chlorophenylhydrazone, and N,N'-dicyclohexylcarbodiimide (DCCD) singly or in combination. Uptake of [3H]tetraphenylphosphonium by the treated cells was employed as a measure of ...

a series of non-cyclic polyethers with different end groups and chain length were used for the extraction of lithium salt from aqueous into various organic phases viz. chloroform, carbon tetrachloride, 1,2-dichloroethane, to study the influence of structural variations within the extractant molecule upon the extraction selectivity and efficiency. the ionophores used were viz. deg (i), degdme (i...

Two polyether ionophores, maduramicin and alborixin, were evaluated for anticryptosporidial activity in a severe combined immune deficient (SCID) mouse model of cryptosporidiosis. Groups of SCID mice were inoculated with 10(6) oocysts of bovine origin by oral gavage. Maduramicin or alborixin was administered beginning 4 weeks postinfection at 3 mg/kg of body weight per day. Maduramicin treatmen...

Polyether ionophores, monensin, and salinomycin are commonly used as antiparasitic drugs in broiler production and may be present in broiler litter (bird excreta plus bedding material). Long-term application of broiler litter to pastures may lead to ionophore contamination of surface waters. Because polyether ionophores break down at low pH, we hypothesized that decreasing litter pH with an aci...

OBJECTIVE To determine if ionophore-resistant ruminal bacteria are cross-resistant to other classes of antibiotics. Clostridium aminophilum was used as a model organism because this Gram-positive ruminal bacterium can adapt to ionophores (monensin and lasalocid). Non-adapted cultures lagged for at least 12 h with 1 microM monensin or lasalocid, but initiated no growth if the concentration was 1...