We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator-prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a kille...

Thymidine incorporation by HEp-2 cells was reduced 10-fold by 2.5 mM hydroxyurea (HU). The DNA in lysates from untreated cells sedimented through alkaline sucrose gradients as an aggregate plus a smaller component which could be chased into the aggregate. Only small DNA (ca. 47 S) was synthesized in nuclei when cells were incubated with HU. HU inhibition was reversible up-to 24 hr. Removal of i...

A terbium complex has been designed that may be used to sensitise formation of singlet oxygen (phi(em) 12%), allowing the creation of a ratiometric sensory system for pO(2) (versus the insensitive Eu analogue) and the definition of a reactive probe that can be used to cause local damage to cells loaded with the complex and exposed to laser excitation.

In common with other bioreductive drugs, metabolic reduction is required for activation of the benzotriazine-di-N-oxide tirapazamine (TPZ) in hypoxic regions of tumors. This same metabolism also consumes the drug as it diffuses, impeding its penetration into hypoxic tissue. In this study, we develop a pharmacokinetic (PK)/pharmacodynamic (PD) model for TPZ that explicitly includes its diffusion...

Aspergillus fumigatus is the most important airborne fungal pathogen causing life-threatening infections in immunocompromised patients. Macrophages and neutrophils are known to kill conidia, whereas hyphae are killed mainly by neutrophils. Since hyphae are too large to be engulfed, neutrophils possess an array of extracellular killing mechanisms including the formation of neutrophil extracellul...

Cytotoxic lymphocytes (CTL) have been reported to show a range of motility patterns from rapid long-range tracking to complete arrest, but how and whether these kinematics affect their ability to kill target cells is not known. Many in vitro killing assays utilize cell lines and tumour-derived cells as targets, which may be of limited relevance to the kinetics of CTL-mediated killing of somatic...

INTRODUCTION ........................................................ 291 General ............... ......................................... 291 Cell Waill Structure and Synthesis ....................... ........................ 292 Identification of the Target of Penicillin Action .......... ........................ 293 PENICILLIN-BINDING COMPONENTS .............. .......................... 296...

We have recently reported (D.L. Stevens, K.A. Maier, B.M. Laine, and J.E. Mitten, J. Infect. Dis. 155:220-228, 1987) that clindamycin, rifampin, and tetracycline were more efficacious than penicillin in the treatment of fulminant gas gangrene in mice caused by Clostridium perfringens. We hypothesize that antibiotic efficacy correlated with bactericidal or toxin-suppressing properties of these a...

Antimicrobial cationic peptides are ubiquitous in nature and are thought to be a component of the first line of defense against infectious agents. It is widely believed that the killing mechanism of these peptides on bacteria involves an interaction with the cytoplasmic membrane. Cationic peptides from different structural classes were used in experiments with Staphylococcus aureus and other me...

BACKGROUND Novel therapeutic approaches for endometriosis based on molecular strategies may prove to be useful. Conditionally replicative adenoviruses (CRAds) are designed to exploit key differences between target and normal cells. The wild-type adenovirus (Adwt) promoter can be replaced by tissue-specific promoters, allowing viral replication only in target cells. Viral infectivity can be enha...