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Aims: To determine how the microbicide ceragenin‐13 (CSA‐13) kills Bacillus subtilis spores prepared on growth or sporulation media, and these spores' properties. Methods and Results: Spores made on Luria broth (LB) growth or double‐strength Schaeffer's‐glucose (2xSG) sporulation plates found that spores made on LB plates have coat defects as evidenced by their lower hypochlorite resistance, faster germination with dodecylamine and slower germination with Ca2+‐dipicolinic acid (CaDPA) than 2xSG plate spores. CSA‐13 triggered CaDPA release from spores, an early step in germination, but only well at 70°C and better with spores made on LB than on 2xSG plates. Approximately 90% of spores with elevated levels of SpoVA proteins that form a CaDPA release channel, released CaDPA with CSA‐13 at 70°C, and faster with spores made on LB than 2xSG plates. Levels of CSA‐13 killing of spores made on LB and 2xSG plates were similar to levels of CaDPA release triggered by this agent. Conclusions: CSA‐13 kills bacterial spores, but only at high concentrations and temperatures, and is preceded by CaDPA release. Significance and Impact of the Study: CSA‐13 is not a direct sporicide as reported previously, but most likely germinates spores via activation of spores' CaDPA channel, albeit inefficiently, and then killing the germinated spores. [ABSTRACT FROM AUTHOR]

In addition to modulating insulin-like growth factors action, it is now clear that insulin-like growth factor-binding protein-3 also has intrinsic effects on cell growth and survival. We have compared the effects of insulin-like growth factor-binding protein-3 and transforming growth factor-beta on cell proliferation and death of Hs578T cells and the normal breast epithelial cell line, MCF-10A. The growth of MCF-10A cells was inhibited at low concentrations of insulin-like growth factor-binding protein-3 but stimulated at high concentrations. These differential effects were unaffected in the presence of an insulin-like growth factor-I receptor antagonist. A synthetic peptide corresponding to the serine phosphorylation domain of insulin-like growth factor-binding protein-3 (that does not bind to insulin-like growth factors) also mimicked these differential actions. The growth of both cell lines was significantly inhibited by transforming growth factor-beta, this was associated with a 14-fold increase of insulin-like growth factor-binding protein-3 secreted by the Hs578T cells but a five-fold decrease of insulin-like growth factorbinding protein-3 secreted by MCF-10A cells. Replacement doses of exogenous insulin-like growth factor-binding protein-3 overcame the transforming growth factor-beta-induced growth inhibition in the MCF-10A cells. Cell death induced by ceramide was significantly reduced by insutin-like growth factor-binding protein-3 in the MCF-10A cells and depleting insulinlike growth factor-binding protein-3 with transforming growth factor-beta in these cells consequently increased their susceptibility to ceramide. In contrast, insulin-like growth factor-binding protein-3 enhanced apoptosis induced by ceramide in the Hs578T cells but transforming growth factor-beta treated Hs578T cells were resistant to apoptosis. The addition of antisense mRNA to insulin-like growth factor-binding protein-3 significantly abrogated this effect of transforming growth... [ABSTRACT FROM AUTHOR]