Cyclic-di-GMP signalling and biofilm-related properties of the Shiga toxin- producing 2011 German outbreak Escherichia coli O104:H4

In 2011, nearly 4,000 people in Germany were infected by Shiga toxin (Stx)-producing Escherichia coli O104:H4 with > 22% of patients developing haemolytic uraemic syndrome (HUS). Genome sequencing showed the outbreak strain to be related to enteroaggregative E. coli (EAEC), suggesting its high virulence results from EAEC-typical strong adherence and biofilm formation combined to Stx production. Here, we report that the outbreak strain contains a novel diguanylate cyclase (DgcX)—producing the biofilm-promoting second messenger c-di-GMP—that shows higher expression than any other known E. coli diguanylate cyclase. Unlike closely related E. coli, the outbreak strain expresses the c-di-GMP-controlled biofilm regulator CsgD and amyloid curli fibres at 37°C, but is cellulose-negative. Moreover, it constantly generates derivatives with further increased and deregulated production of CsgD and curli. Since curli fibres are strongly proinflammatory, with cellulose counteracting this effect, high c-di-GMP and curli production by the outbreak O104:H4 strain may enhance not only adherence but may also contribute to inflammation, thereby facilitating entry of Stx into the bloodstream and to the kidneys where Stx causes HUS

Transition State Analysis of the Reaction Catalyzed by the Phosphotriesterase from Sphingiobium sp. TCM1

Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The phosphotriesterase from Sphingobium sp. TCM1 (Sb-PTE) is one of the few enzymes known to be able to hydrolyze organophosphorus flame retardants such as triphenyl phosphate and tris(2-chloroethyl) phosphate. The effectiveness of Sb-PTE for the hydrolysis of these organophosphates appears to arise from its ability to hydrolyze unactivated alkyl and phenolic esters from the central phosphorus core. How Sb-PTE is able to catalyze the hydrolysis of the unactivated substituents is not known. To interrogate the catalytic hydrolysis mechanism of Sb-PTE, the pH dependence of the reaction and the effects of changing the solvent viscosity were determined. These experiments were complemented by measurement of the primary and secondary 18-oxygen isotope effects on substrate hydrolysis and a determination of the effects of changing the pKa of the leaving group on the magnitude of the rate constants for hydrolysis. Collectively, the results indicated that a single group must be ionized for nucleophilic attack and that a separate general acid is not involved in protonation of the leaving group. The Brønsted analysis and the heavy atom kinetic isotope effects are consistent with an early associative transition state with subsequent proton transfers not being rate limiting. A novel binding mode of the substrate to the binuclear metal center and a catalytic mechanism are proposed to explain the unusual ability of Sb-PTE to hydrolyze unactivated esters from a wide range of organophosphate substrates

Human immunodeficiency virus and other sexually transmitted diseases in Cuban women

ABSTRACTA cross-sectional study was performed in 60 Cuban women of child-bearing age who were sero-positive for human immunodeficiency virus (HIV) and 60 controls. Human papillomavirus (HPV) was identified most frequently, with oncogenic HPV serotypes 16, 33 and 58 detected in HIV-positive patients, and serotypes 11, 33 and 51 in the controls (relative risk 4.41; 95% CI 2.21– 8.29). Syphilis and hepatitis B and C viruses were detected exclusively in HIV-sero-positive women (p < 0.05). Sexually transmitted diseases (STDs) appeared to pose a substantial health problem, especially for HIV-positive women. Clinics should consider screening and treatment for STDs as part of their HIV prevention programmes

Sample cartridge with built in miniature molecule evaporator for in situ measurement with a photoemission electron microscope

We present a new sample holder that is compatible with Photoemission Electron Microscopes PEEMs and contains a molecule evaporator. With the integrated low cost evaporator, a local and controlled material deposition in clean ultra high vacuum conditions can be achieved minimizing the contamination of the analysis chamber. Different molecule systems can easily be studied by exchanging the sample holder. This opens up new possibilities for in situ investigation of thin film growth by means of spectromicroscopy and element selective imaging at the nanometer scale. As an example of the performances of the setup, we present a study of the hybrid inorganic organic system HIOS consisting of the organic acceptor molecule 2,2 amp; 8242; perfluoronaphthalene 2,6 diylidene dimalononitrile F6TCNNQ and ZnO, which is of great interest for novel HIOS based optoelectronic devices. Here, the ZnO surface work function modification by F6TCNNQ adsorption is investigated in situ in a spatially resolved manner. In addition, we employ PEEM to selectively probe the chemical state of F6TCNNQ molecules in contact with ZnO in the first monolayer and those molecules located in multilayers in 3D island

Modelling and Analysis of Central Metabolism Operating Regulatory Interactions in Salt Stress Conditions in a L-Carnitine Overproducing E. coli Strain

Based on experimental data from E. coli cultures, we have devised a mathematical model in the GMA-power law formalism that describes the central and L-carnitine metabolism in and between two steady states, non-osmotic and hyperosmotic (0.3 M NaCl). A key feature of this model is the introduction of type of kinetic order, the osmotic stress kinetic orders (gOSn), derived from the power law general formalism, which represent the effect of osmotic stress in each metabolic process of the model

ITO free OLEDs utilizing inkjet printed and low temperature plasma sintered Ag electrodes

We report an inkjet printed indium tin oxide ITO free electrode made from a particle free silver ink. After printing, an argon plasma is used to reduce the silver ions in the ink to metallic silver. This process does not require high temperatures and is therefore suitable for use with temperature sensitive substrates. Printed silver layers show good optical transmittance and electrical conductivity. To demonstrate the capabilities of the electrodes, inverted ITO free organic light emitting diodes OLEDs were produced via solution processing. In terms of luminance and efficacy, the devices containing the printed electrodes show improved luminance and current efficacy compared to ITO based reference devices. When fabricated with flexible substrates, the printed OLEDs show high bending stability, enabling flexible application

Imiquimod Does not Affect Shedding of Viable Chlamydiae in a Murine Model of Chlamydia trachomatis Genital Tract Infection

Objective: We postulated that either oral or vaginal administration of the immune response modifier imiquimod would decrease vaginal shedding of Chlamydia trachomatis, mouse pneumonitis strain (MoPn), in a murine model. Methods: Female BALB/c mice were infected intravaginally withC. trachomatis (MoPn) and were administered imiquimod either orally (30 mg/kg) or vaginally (10 μl of 5%imiquimod cream) prior to infection and every second day after infection for a total of four doses. The course of infection was monitored by collecting cervical–vaginal swabs and isolation in HeLa 229 cell culture. To determine whether the drug affected T helper type 1 or T helper type 2 immune response polarization, immunoglobulinG(IgG) subclass antibody responses were assessed at day 56 after infection. Results: There was no significant difference in the course of infection when imiquimod-treated mice were compared with sham-treated controls, regardless of whether the drug was administered orally or vaginally. IgG subclass antibody responses, and by extension, T helper type 1 to T helper type 2 immune response polarization, were also unaffected. Conclusions: Imiquimod has no efficacy in controllingC. trachomatis (MoPn) infection in the murine model