ABSTRACT
The development of pathogenic bacteria resistant to current treatments is a major issue facing the world today. Here, the synthesis and biological activity of fourth generation poly(amidoamine) dendrimers decorated with 1-hexadecyl-azoniabicylo[2.2.2]octane (C16-DABCO), a quaternary ammonium compound known to have antibacterial activity, are described. This highly cationic dendrimer antibiotic was tested against several Gram positive and Gram negative strains of pathogenic bacteria and exhibited activity against both. Higher activity toward the Gram positive strains that were tested was observed. After the antimicrobial activity was assessed, E. coli and B. cereus were subjected to a resistance selection study. This study demonstrated that a multivalent approach to antimicrobial design significantly reduces the likelihood of developing bacterial resistance. Highly cationic dendrimers were also used as pretreatment of a membrane to prevent biofilm formation.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Dendrimers/chemistry , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Quaternary Ammonium Compounds/chemistry , Quaternary Ammonium Compounds/pharmacologyABSTRACT
The prion agent has been detected in skeletal muscle of humans and animals with prion diseases. Here we report scrapie infection of murine C2C12 myoblasts and myotubes in vitro following coculture with a scrapie-infected murine neuroblastoma (N2A) cell line but not following incubation with a scrapie-infected nonneuronal cell line or a scrapie brain homogenate. Terminal differentiation of scrapie-infected C2C12 myoblasts into myotubes resulted in an increase in the expression of the disease-specific prion protein, PrP(Sc). The amount of scrapie infectivity or PrP(Sc) in C2C12 myotubes was comparable to the levels found in scrapie-infected N2A cells, indicating that a high level of infection was established in muscle cells. Subclones of scrapie-infected C2C12 cells produced high levels of PrP(Sc) in myotubes, and the C-terminal C2 polypeptide fragment of PrP(Sc) was found based on deglycosylation and PrP(Sc)-specific immunoprecipitation of cell lysates. This is the first report of a stable prion infection in muscle cells in vitro and of a long-term prion infection in a nondividing, differentiated peripheral cell type in culture. These in vitro studies also suggest that in vivo prion infection of skeletal muscle requires contact with prion-infected neurons or, possibly, nerve terminals.
Subject(s)
Muscle, Skeletal/metabolism , Myoblasts/metabolism , Prions/metabolism , Animals , Blotting, Western , Cell Differentiation/physiology , Cell Line , Desmin/metabolism , Electrophoresis, Polyacrylamide Gel , Fluorescent Antibody Technique , Immunoprecipitation , Mice , Myoblasts/physiologyABSTRACT
The plasminogen activator-plasmin cascade is involved in multiple physiological and pathological processes including fibrinolysis, wound healing, fibrosis, angiogenesis, embryo implantation and tumor cell invasion and metastasis. Plasminogen activator-inhibitor type 1 (PAI-1) is the major physiological regulator of plasminogen activation. PAI-1 is expressed in a variety of mammalian cells and is regulated by growth factors, cytokines and hormones, including agents that elevate cAMP levels. Although cyclic nucleotide regulation of PAI-1 is observed in diverse cell types in various species, including human, limited studies have addressed the mechanism of this regulation. Here we review our work on the regulation of PAI-1 mRNA degradation in HTC rat hepatoma cells, describing the cis-acting cAMP-responsive sequence in the transcript and a novel RNA binding protein that interacts with it. Potential mechanisms by which this RNA-binding protein may be involved in cyclic nucleotide regulation of mRNA stability are discussed and cAMP regulation of PAI-1 in other systems is summarized.
