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The peroxide response transcriptional regulator, PerR, is thought to contribute to virulence of group A Streptococcus (GAS); however, the specific mechanism through which it enhances adaptation for survival in the human host remains unknown. Here, we identify a critical role of PerR-regulated gene expression in GAS phagocytosis resistance and in virulence during pharyngeal infection. Deletion of p

Streptolysin O (SLO) is a cholesterol-dependent cytolysin produced by the important human pathogen, group A Streptococcus (Streptococcus pyogenes or GAS). In addition to its cytolytic activity, SLO mediates the translocation of GAS NAD-glycohydrolase (NADase) into human epithelial cells in vitro. Production of both NADase and SLO is associated with augmented host cell injury beyond that produced b

CsrRS (or CovRS) is a two-component system implicated in the control of multiple virulence determinants in the important human pathogen, group A Streptococcus (GAS). Earlier studies suggested that extracellular Mg(2+) signalled through the presumed sensor histidine kinase, CsrS. We now confirm those findings, as complementation of a csrS mutant restored Mg(2+)-dependent gene regulation. Moreover,

Group A Streptococcus (GAS) colonizes the oropharynx and damaged skin. To cause local infection or severe invasive syndromes the bacteria must gain access into deeper tissues. Host cell death may facilitate this process. GAS internalization has been identified to induce apoptosis. We now report an alternate mechanism of GAS-mediated apoptosis of primary human keratinocytes, initiated by extracellu

Local host defenses limit proliferation and systemic spread of pathogenic bacteria from sites of mucosal colonization. For pathogens such as streptococci that fail to grow intracellularly, internalization and killing by epithelial cells contribute to the control of bacterial growth and dissemination. Here, we show that group A Streptococcus (GAS), the agent of streptococcal sore throat and invasiv

The present study was initiated to gain insight into the interaction between splenic dendritic cells (DC) and Salmonella enterica serovar Typhimurium in vivo. Splenic phagocytic cell populations associated with green fluorescent protein (GFP)-expressing bacteria and the bacterium-specific T-cell response were evaluated in mice given S. enterica serovar Typhimurium expressing GFP and ovalbumin. Flo

1. In normal mice, the distribution of adrenergic, cholinergic, some peptidergic, and neuronal nitric oxide synthase (nNOS)-containing nerves were investigated. Functional in vitro correlates were obtained. An in vivo model was developed in which erectile haemodynamics in response to drugs or nerve-stimulation were studied. 2. Immunoreactivities for vesicular acetylcholine transporter protein (VAC

We have examined whether in vivo exposure to the glutamate analogue, kainic acid, induces cell loss through apoptosis and/or through necrosis. The vulnerability of rabbit retinal cells was evaluated by routine histopathology. The DNA fragmentation was examined using an in situ method (TUNEL: TdT-mediated biotin-dUTP nick-end labelling) and agarose gel electrophoresis of extracted retinal DNA. Reti

This study analyzed the effect of breast-feeding on the frequency of acute otitis media. The protocol was designed to examine each child at 2, 6 and 10 months of age. At each visit nasopharyngeal cultures were obtained, the feeding pattern was recorded and the acute otitis media (AOM) episodes were documented. The analysis was based on 400 children from whom complete information was obtained. They

Change is sweeping through the world of museums, technologically, financially, and ideologically, impacting on the sociocultural evolution of their roles and status. We seek to contribute to ongoing reflections by offering a conceptual framework that links museums with democratic theory, to citizenship and its practices – a domain that is also in notable transition. We connect concretely with the

To talk about the internet as a civic space requires some preliminary conceptualization; thus, first I briefly discuss two models of democracy – elitist and republican – to show that the ideals of civic participation can vary considerably. This is illuminated by a discussion of the role of the net in electoral and alternative politics. From there I approach civic space through two key concepts: ci