Unraveling the molecular determinants of the anti-phagocytic protein cloak of plague bacteria.

The pathogenic bacterium Yersina pestis is protected from macrophage engulfment by a capsule like antigen, F1, formed of long polymers of the monomer protein, Caf1. However, despite the importance of this pathogen, the mechanism of protection was not understood. Here we demonstrate how F1 protects the bacteria from phagocytosis.

Cultured enterocytes internalise bacteria across their basolateral surface for, pathogen-inhibitable, trafficking to the apical compartment.

In vitro- and in vivo-polarised absorptive epithelia (enterocytes) are considered to be non-phagocytic towards bacteria with invasive pathogenic strains relying on virulence factors to 'force' entry. Here, we report a serendipitous discovery that questions these beliefs. Thus, we uncover in well-established models of human small (Caco-2; TC-7) and large (T84) intestinal enterocytes a polarization-dependent mechanism that can transfer millions of bacteria from the basal to apical compartment.

Nck adaptors, besides promoting N-WASP mediated actin-nucleation activity at pedestals, influence the cellular levels of enteropathogenic Escherichia coli Tir effector.

Enteropathogenic Escherichia coli (EPEC) binding to human intestinal cells triggers the formation of disease-associated actin rich structures called pedestals. The latter process requires the delivery, via a Type 3 secretion system, of the translocated Intimin receptor (Tir) protein into the host plasma membrane where binding of a host kinase-modified form to the bacterial surface protein Intimin triggers pedestal formation. Tir-Intimin interaction recruits the Nck adaptor to a Tir tyrosine phosphorylated residue where it activates neural Wiskott-Aldrich syndrome protein (N-WASP); initiating the major pathway to actin polymerization mediated by the actin-related protein (Arp) 2/3 complex.

Insights into the pathogenesis of enteropathogenic E. coli using an improved intestinal enterocyte model.

Enteropathogenic E. coli (EPEC) is a human pathogen that targets the small intestine, causing severe and often fatal diarrhoea in infants. A defining feature of EPEC disease is the loss (effacement) of absorptive microvilli (MV) from the surface of small intestinal enterocytes.

A bacterial encoded protein induces extreme multinucleation and cell-cell internalization in intestinal cells.

Despite extensive study, the molecular mechanisms that lead to multinucleation and cell enlargement (hypertrophy) remain poorly understood. Here, we show that a single bacterial virulence protein, EspF, from the human pathogen enteropathogenic E. coli induces extreme multi-nucleation in small intestinal epithelial cells.

The enteropathogenic E. coli (EPEC) Tir effector inhibits NF-κB activity by targeting TNFα receptor-associated factors.

Enteropathogenic Escherichia coli (EPEC) disease depends on the transfer of effector proteins into epithelia lining the human small intestine. EPEC E2348/69 has at least 20 effector genes of which six are located with the effector-delivery system genes on the Locus of Enterocyte Effacement (LEE) Pathogenicity Island. Our previous work implied that non-LEE-encoded (Nle) effectors possess functions that inhibit epithelial anti-microbial and inflammation-inducing responses by blocking NF-κB transcription factor activity.

Cell-surface nucleolin is sequestered into EPEC microcolonies and may play a role during infection.

Nucleolin is a prominent nucleolar protein that is mobilized into the cytoplasm during infection by enteropathogenic Escherichia coli (EPEC). Nucleolin also exists at low levels at the cell surface of eukaryotic cells and here we show that upon infection of an intestinal cell model, EPEC recruits and subsequently sequesters cell-surface EGFP-nucleolin into extracellularly located bacterial microcolonies. The recruitment of nucleolin was evident around bacteria within the centre of the microcolonies that were not directly associated with actin-based pedestals.

PKA-mediated phosphorylation of EPEC-Tir at serine residues 434 and 463: A novel pathway in regulating Rac1 GTPase function.

Type-III or type-IV secretion systems of many Gram-negative bacterial pathogens inject effector proteins into host cells that modulate cellular functions in their favour. A preferred target of these effectors is the actin-cytoskeleton as shown by studies using the gastric pathogens Helicobacter pylori (H. pylori) and enteropathogenic Escherichia coli (EPEC).

Safety and efficacy of Gamma Knife surgery for brain metastases in eloquent locations.

Object: Brain metastases are the most frequently occurring cerebral tumors. Tumors that are located in eloquent cerebral parenchyma can cause considerable morbidity and may pose a significant challenge during surgery. Gamma Knife surgery (GKS) is a recognized treatment modality for brain metastases.

Proteasome-independent degradation of canonical NFkappaB complex components by the NleC protein of pathogenic Escherichia coli.

The NFκB transcription factor is a key component of immune and inflammatory signaling as its activation induces the expression of antimicrobial reagents, chemokines, cytokines, and anti-apoptotic factors. Many pathogens encode effector proteins that target factors regulating NFκB activity and can provide novel insights on regulatory mechanisms. Given the link of NFκB dysfunction with inflammatory diseases and some cancers, these effectors have therapeutic potential.

Gamma Knife surgery for hypothalamic hamartomas causing refractory epilepsy: preliminary results from a prospective observational study.

Object: Hypothalamic hamartomas (HHs) are congenital lesions typically presenting with medically refractory epilepsy. Open or endoscopic surgical procedures to remove or disconnect the hamartoma have been reported to be effective but are associated with significant morbidity. The authors of studies on Gamma Knife surgery for HHs have reported an encouraging rate of epilepsy resolution with minimal side effects.

The enteropathogenic E. coli effector EspF targets and disrupts the nucleolus by a process regulated by mitochondrial dysfunction.

The nucleolus is a multifunctional structure within the nucleus of eukaryotic cells and is the primary site of ribosome biogenesis. Almost all viruses target and disrupt the nucleolus--a feature exclusive to this pathogen group. Here, using a combination of bio-imaging, genetic and biochemical analyses, we demonstrate that the enteropathogenic E.

The bacterial effectors EspG and EspG2 induce a destructive calpain activity that is kept in check by the co-delivered Tir effector.

Bacterial pathogens deliver multiple effector proteins into eukaryotic cells to subvert host cellular processes and an emerging theme is the cooperation between different effectors. Here, we reveal that a fine balance exists between effectors that are delivered by enteropathogenic E. coli (EPEC) which, if perturbed can have marked consequences on the outcome of the infection.

Evidence of descending inhibition deficits in atypical but not classical trigeminal neuralgia.

Trigeminal neuralgia (TN) is a rare neuropathic facial pain disorder. Two forms of TN, classical TN (CTN) and atypical TN (ATN), are reported and probably have different aetiologies. The aim of the present study was to evaluate the functional integrity of the diffuse noxious inhibitory controls (DNIC) in (1) a group of patients with classical trigeminal neuralgia (CTN), (2) a group of patients with atypical trigeminal neuralgia (ATN), and (3) a group of healthy controls in order to determine if a descending pain modulation deficit could participate in the pathophysiology of TN pain.

Dual infection system identifies a crucial role for PKA-mediated serine phosphorylation of the EPEC-Tir-injected effector protein in regulating Rac1 function.

Many Gram-negative pathogenic bacteria possess type-III or type-IV secretion systems to inject 'effector' proteins directly into host cells to modulate cellular processes in their favour. A common target is the actin-cytoskeleton linked to the delivery of a single (CagA) effector by Helicobacter pylori and multiple effectors by enteropathogenic Escherichia coli (EPEC) respectively. Here we report co-infection as a powerful strategy for defining effector protein function and mechanisms by which they modulate cellular responses.

Trigeminal neuralgia: outcomes after gamma knife radiosurgery.

Background: Trigeminal neuralgia (TN) often remains difficult to treat despite multiple available medications, and can severely impact on the quality of life of affected patients. Gamma knife radiosurgery has recently emerged as a minimally-invasive alternative to surgery for patients suffering from drug-resistant TN. The goal of this study was to report the short-term efficacy of gamma knife radiosurgery for TN and assess its impact on the quality of life of patients treated in the first 18 months of our experience.

The effector repertoire of enteropathogenic E. coli: ganging up on the host cell.

Diarrhoeal disease caused by enteropathogenic E. coli (EPEC) is dependent on a delivery system that injects numerous bacterial 'effector' proteins directly into host cells. The best-described EPEC effectors are encoded together on the locus of enterocyte effacement (LEE) pathogenicity island and display high levels of multifunctionality and cooperativity within the host cell.

Complications of Gamma Knife surgery: an early report from 2 Canadian centers.

Object: Gamma Knife surgery (GKS) is used to treat benign and malignant brain tumors, arteriovenous malformations, trigeminal neuralgia, and other conditions. Patients experience reduced neurological morbidity from GKS compared with open microneurosurgery, but risks of radiation injury and technical limitations persist. The authors report treatment complications from the early experience of 2 Canadian GKS programs in Toronto and Sherbrooke.

Complete genome sequence and comparative genome analysis of enteropathogenic Escherichia coli O127:H6 strain E2348/69.

Enteropathogenic Escherichia coli (EPEC) was the first pathovar of E. coli to be implicated in human disease; however, no EPEC strain has been fully sequenced until now. Strain E2348/69 (serotype O127:H6 belonging to E.

Tumor bed radiosurgery after resection of cerebral metastases.

Objective: Adjuvant irradiation after resection of brain metastases reduces the risk of local recurrence. Whole-brain radiation therapy can be associated with significant neurotoxicity in long-term survivors of brain metastases. This retrospective study evaluates the role of tumor bed stereotactic radiosurgery as an alternative method of irradiation after initial resection of brain metastases to prevent local recurrence.

Tir phosphorylation and Nck/N-WASP recruitment by enteropathogenic and enterohaemorrhagic Escherichia coli during ex vivo colonization of human intestinal mucosa is different to cell culture models.

Tir, the translocated intimin receptor of enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) and Citrobacter rodentium, is translocated into the host cell by a filamentous type III secretion system. Epithelial cell culture has demonstrated that Tir tyrosine phosphorylation is necessary for attaching effacing (A/E) lesion formation by EPEC and C. rodentium, but is not required by EHEC O157:H7.

Enteropathogenic Escherichia coli (EPEC) inactivate innate immune responses prior to compromising epithelial barrier function.

Enteropathogenic Escherichia coli (EPEC) infection of the human small intestine induces severe watery diarrhoea linked to a rather weak inflammatory response despite EPEC's in vivo capacity to disrupt epithelial barrier function. Here, we demonstrate that EPEC flagellin triggers the secretion of the pro-inflammatory cytokine, interleukin (IL)-8, from small (Caco-2) and large (T84) intestinal epithelia model systems. Interestingly, IL-8 secretion required basolateral infection of T84 cells implying that flagellin must penetrate the epithelial barrier.

The enteropathogenic Escherichia coli EspF effector molecule inhibits PI-3 kinase-mediated uptake independently of mitochondrial targeting.

Delivery of effector molecules into LMme(v) macrophages by enteropathogenic Escherichia coli, via its type three secretion system (T3SS), inhibits bacterial uptake by a phosphatidylinositol-3 (PI-3) kinase-dependent pathway. The T3SS system, encoded by the locus of enterocyte effacement (LEE) pathogenicity island, delivers LEE- and non-LEE-encoded effector proteins into host cells. Previous studies discounted essential roles for the LEE-encoded Map, EspF, Tir or Intimin proteins in this process but correlated it with loss of phosphorylation of the PI-3 kinase substrate, Akt (Celli et al.