Novel N-α-haloacylated homoserine lactones, in which a halogen atom was introduced at the α-position of the carbonyl function of the N-acyl chain, have been studied as quorum sensing (QS) modulators and compared with a library of natural N-acylated homoserine lactones (AHLs). The series of novel analogues consists of α-chloro, α-bromo and α-iodo AHL analogues. Furthermore, the biological QS act...

Biofilm development and quorum sensing (QS) are closely interconnected processes. Biofilm formation is a cooperative group behaviour that involves bacterial populations living embedded in a self-produced extracellular matrix. QS is a cell-cell communication mechanism that synchronizes gene expression in response to population cell density. Intuitively, it would appear that QS might coordinate t...

Most bacteria in nature exist as biofilms, which support intercellular signalling processes such as quorum sensing (QS), a cell-to-cell communication mechanism that allows bacteria to monitor and respond to cell density and changes in the environment. As QS and biofilms are involved in the ability of bacteria to cause disease, there is a need for the development of methods for the non-invasive ...

Schmüdgen proved a Positivstellensatz about the representation of positive definite polynomials on a basic closed semialgebraic set using methods from functional analysis in connection with Stengle's Positivstellensatz. Later Wörmann gave a purely algebraic proof. The present note contains yet another proof that uses classical results by Kadison about the representation of partially ordered alg...

Pathogenic bacteria use interconnected multi-layered regulatory networks, such as quorum sensing (QS) networks to sense and respond to environmental cues and external and internal bacterial cell signals, and thereby adapt to and exploit target hosts. Despite the many advances that have been made in understanding QS regulation, little is known regarding how these inputs are integrated and proces...

Serratia marcescens is an opportunistic pathogen and a major cause of ocular infections. In previous studies of S. marcescens MG1, we showed that biofilm maturation and sloughing were regulated by N-acyl homoserine lactone (AHL)-based quorum sensing (QS). Because of the importance of adhesion in initiating biofilm formation and infection, the primary goal of this study was to determine whether ...

the goal of this study was to prepare and characterize alginate microspheres as an antigen delivery system and adjuvant for immunization against leishmaniasis. microspheres encapsulated with autoclaved leishmania major (alm) and quillaja saponin (qs) were prepared by an emulsification technique and characterized for size, encapsulation efficiency and release profile of encapsulates. selection o...

BACKGROUND The recent introduction of the automated cardiac flow measurement (ACM) method, using spatiotemporal integration of the Doppler velocity profile, provides a quick and accurate automated calculation of cardiac output. OBJECTIVE To evaluate the ACM method against oximetry during cardiac catheterisation for estimating the Qp/Qs (pulmonary to systemic flow) ratio in patients with an at...

BACKGROUND Perioperative management of patients with complete mixing of pulmonary and systemic blood centers on approximately equating pulmonary (Qp) and systemic (Qs) blood flow (Qp/Qs approximately 1). This empirically derived target is opposed by theoretical studies advocating a target Qp/Qs well below 1. We studied the cause of this persistent discrepancy. METHODS AND RESULTS Classic theo...

Quorum sensing (QS) in Sinorhizobium meliloti, the N-fixing bacterial symbiont of Medicago host plants, involves at least half a dozen different N-acyl homoserine lactone (AHL) signals and perhaps an equal number of AHL receptors. The accumulation of 55 proteins was found to be dependent on SinI, the AHL synthase, and/or on ExpR, one of the AHL receptors. Gas chromatography-mass spectrometry an...