Regulation and expression of human Fabs under the control of the Escherichia coli arabinose promoter, PBAD

BACKGROUND: The L-arabinose operon from E. coli contains an inducible promoter PBAD which has been extensively studied for the control of gene expression. PBAD has a number of potential advantages over Plac, and has been used successfully to promote high level expression of recombinant proteins. OBJECTIVES: The aim of this study was to investigate PBAD as an alternative system to Plac for the bacterial expression of recombinant Fabs. STUDY DESIGN: The promoter PBAD from the E. coli arabinose operon araBAD and the gene encoding the regulator of this promoter, were cloned into the phagemid expression vector MCO1. Expression of human recombinant tetanus toxoid (TT) and c-erbB2 Fabs under the control of PBAD was compared at two induction temperatures with the same Fabs produced under the control of Plac. RESULTS: Expression of TT and c-erbB2 Fabs under the control of PBAD was comparable to Fab expression from Plac. However, highly expressed TT Fab under the control of PBAD was localised to the soluble periplasmic fraction whereas under the control of Plac, there was greater leakage of Fab into the culture supernatant. In addition, Fab expression from PBAD could be more tightly repressed than from Plac. CONCLUSION: PBAD is a useful and cheaply inducible alternative to the more commonly used Plac for the rapid expression of soluble recombinant human antibody fragments.     

Histopathological lesions in lead intoxicated dogs

Epidermoid cysts (ECs) are rare developmental lesions occurring anywhere along the central nervous system. Usually affecting adult patients, the occurrence of supratentorial dorsal cistern ECs has been reported in only 1 certain case of pediatric age. An additional pediatric case is presented. An 11-year-old boy had an 8-year history of petit mal seizures. Neurologic examination on admission was negative. T1-weighted magnetic resonance images demonstrated homogenous, hypointense, intradural, extracerebral, right frontal, precentral, parasagittal mass with relatively high signal intensity on T2-weighted images. The lesion was completely removed using a microneurosurgical technique with special care taken with regard to the adjacent nervous and vascular structures. Histologically, an EC was diagnosed. The patient had no recurrence for 2 years and seizures were significantly reduced. This case suggests the need to include ECs in the differential diagnosis of intradural supratentorial extracerebral lesions in childhood.     

The Adoption of Mediterranean Diet Attenuates the Development of Acute Coronary Syndromes in People with the Metabolic Syndrome

Objectives  

In this work we investigated the effect of the consumption of the Mediterranean diet on coronary risk, in subjects with the metabolic syndrome.     

Study of CO2 permeation in Zn2+-modified Al2O3-carbonate membrane

Molten carbonate-based membranes for CO₂ capture have received attentions because of their high CO₂ selectivity, potential energy-saving capability and environmental friendliness. Zn²⁺-modified Al₂O₃/carbonates membranes with the enhanced CO₂ permeability have been developed in this work. Interfaces of LiAlO₂ were formed on the surface of Al₂O₃ due to the carbonates incorporation. Microstructural and interfacial characterisation of the membrane revealed that the outermost LiAlO₂ layer was due to the reactions between Li₂CO₃ and ZnAl₂O₄, resulting in the dissolution of ZnO in the molten carbonate. CO₂ permeability of 0.5% ZnAl₂O₄/Al₂O₃/carbonates reached 9.12 × 10⁻¹² mol.m⁻¹s⁻¹ Pa⁻¹ at 700°C, higher than that of Al₂O₃/carbonates, because of the dissolved ZnO. With the increase of ZnAl₂O₄, CO₂ permeability was decreased. The dissolved ZnO in the molten carbonates could enhance the ionic conductivity, whereas a higher amount of ZnO than its solubility will attenuate its effects on CO₂ permeation.     

The role of TiO<Subscript>2</Subscript> layers deposited on YSZ on the electrochemical promotion of C<Subscript>2</Subscript>H<Subscript>4</Subscript> oxidation on Pt

The electrochemical promotion of Pt/YSZ and Pt/TiO₂/YSZ catalyst-electrodes has been investigated for the model reaction of C₂H₄ oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375 °C. It has been found that the presence of a dispersed TiO₂ thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO₂. This significantly enhanced EPOC effect via the addition of TiO₂ suggests that the presence of the porous TiO₂ layer enhances the transport of promoting O²⁻ species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion and three-phase-boundary length in presence of the TiO₂ porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO₂ layer which results to enhanced O²⁻ transport to the Pt surface via a self-driven electrochemical promotion O²⁻ transport mechanism.     

Mechanical and adhesion properties of polymer-modified cement mortars in relation with their microstructure

In this study, cement mortars were modified with a commercial polymer admixture. The aim of this study is to investigate the influence of the polymer content on the mechanical and adhesion properties of the mortars and to relate these properties with mortars’ microstructure. A series of mortars were produced with various polymer/cement/water/aggregate ratios. The adhesion properties of the mortars to clay bricks were tested with a simplified tensile testing measurement. The microstructure of mortars, as well as interfaces, were evaluated by Scanning Electron Microscopy (SEM). It was found that with high polymer content, large size hardened particles are formed, reducing the compressive strength of the mortars. Polymer addition enhances the adhesion between the mortar and brick. The mortar microstructure at the interface affects the adhesion properties and the mode of failure.     

Fission product release in high-burn-up UO2 oxidized to U3O8

Results of oxidation experiments on high-burn-up UO₂ are presented where fission-product vaporisation and release rates have been measured by on-line mass spectrometry as a function of time/temperature during thermal annealing treatments in a Knudsen cell under controlled oxygen atmosphere. Fractional release curves of fission gas and other less volatile fission products in the temperature range 800-2000 K were obtained from BWR fuel samples of 65 GWd t⁻¹ burn-up and oxidized to U₃O₈ at low temperature. The diffusion enthalpy of gaseous fission products and helium in different structures of U₃O₈ was determined.     

An experimental study of the thermally activated processes in polycrystalline silicon thin film transistors

The thermally activated mechanisms that determine the electrical properties of polycrystalline silicon thin film transistors have been investigated. The study employed devices fabricated on long grains and different thickness polycrystalline films, which were obtained by excimer laser annealing crystallization. The transfer and the transient characteristics have been recorded and analysed in the linear operation regime. The temperature dependence of basic parameters such as leakage current, subthreshold swing and drain current overshoot transient amplitude was found to stem from the same thermally activated carriers generation mechanism. The dependence of thermally activated mechanisms on the film thickness suggests that the device operation is strongly related to polycrystalline material properties.     

Accelerated lifetime test of RF-MEMS switches under ESD stress

This paper presents the results of a study on issues of reliability and accelerated life testing for radio frequency micro-electromechanical system (RF-MEMS) capacitive devices. A human-body-model electrostatic discharge tester has been used to induce charging by operating at stress levels much higher than would be expected in normal use. Temperature ranges from 300 K to 330 K allows the understanding of physical mechanisms that may be responsible for the device’s reliability.