Loss and recovery of Humoral Immunity to Influenza Virus following Malaria Infection

The mechanisms of maintenance of humoral immunity to infectious pathogens, particularly the contributions of memory B cells and long-lived plasma cells in maintaining specific serum antibody titres, are not well understood. Furthermore, it is not clear whether sequential heterologous humoral immune responses and disease pathology can result in the dysregulation and loss of previously acquired antibody-mediated immune responses to unrelated antigens. Here, depletion of memory B cells using anti-hCD20 monoclonal antibodies in hCD20 transgenic mice was used to dissect the role of memory B cells and long-lived plasma cells in maintaining long-term serum antibodies after intranasal Influenza A infection. Next, an experimental model of sequential infections with Influenza A/PR/8/34 and Plasmodium chabaudi chabaudi (AS) was set up, with a 15-20 week interval between the infections, in order to investigate whether sequential infection with P. chabaudi would affect pre-established humoral immunity to Influenza A. This study demonstrates that memory B cells are essential for the maintenance of long-lived serum Ab titres to Influenza A, as depletion of memory B cells results in the eventual loss of long-lived plasma cells and serum antibodies. Sequential infection with P. chabaudi results in the loss of pre-established serum antibodies to Influenza A by inducing the loss of long-lived plasma cells in an FcγRI,II,III-dependent manner, and this renders mice susceptible to secondary infection with Influenza A. However, this loss of pre-established humoral immunity is temporary, as serum antibodies do eventually return to normal levels. These findings demonstrate a mechanism shared by memory B cells and long-lived plasma cells which ensures that serum antibodies are maintained for long periods of time in the face of continuous generation and incorporation of new specificities throughout the lifetime of the host. A more complete understanding of the parameters that affect the longevity of immunological memory and how heterologous infections influence this will be vital in our understanding of the effect of continuous exposure to infectious pathogens on the efficacy and longevity of previously established immune memory

Electronic Cigarette Advertising Impacts Adversely on Smoking Behaviour Within a London Student Cohort: A Cross-Sectional Structured Survey.

INTRODUCTION: In contrast to tobacco smoking, electronic cigarette ("vaping") advertisement had been approved in the United Kingdom (UK) in January 2013. Currently, there are an estimated 3.2 million UK e-cigarette users. The impact of e-cigarette advertisement on tobacco use has not been studied in detail. We hypothesised that e-cigarette advertisement impacts on conventional smoking behaviour. METHODS: A cross-sectional structured survey assessed the impact of e-cigarette advertising on the perceived social acceptability of cigarette and e-cigarette smoking and on using either cigarettes or e-cigarettes (on a scale of 1 to 5/'not at all' to 'a lot'). The survey was administered between January to March 2015 to London university students, before and after viewing 5 UK adverts including a TV commercial. RESULTS: Data were collected from 106 participants (22 ± 2 years, 66% male), comprising cigarette smokers (32%), non-smokers (54%) and ex-smokers (14%). This included vapers (16%), non-vapers (77%) and ex-vapers (7%). After viewing the adverts, smokers (2.6 ± 1.0 vs. 3.8 ± 1.1, p = 0.001) and non-smokers (3.2 ± 0.7 vs. 3.7 ± 0.8, p = 0.007) felt smoking was more socially acceptable, compared to before viewing them. Participants were more likely to try both e-cigarettes (1.90 ± 1.03 to 3.09 ± 1.11, p < 0.001) and conventional cigarettes (1.73 ± 0.83 to 2.27 ± 1.13, p < 0.001) after viewing the adverts compared to before. Vapers were less likely to smoke both an e-cigarette, and a conventional cigarette after viewing the adverts. CONCLUSION: E-cigarette advertising encourages both e-cigarette and conventional cigarette use in young smokers and non-smokers. The adverts increase the social acceptability of smoking without regarding the importance of public health campaigns that champion smoking cessation

A new method of producing uniformly distributed alumina particles in Al-based metal matrix composite

Alumina particles reinforced aluminum-based metal matrix composite is produced by sintering an Al-10 wt.%ZnO sample at 1000 degreesC. During sintering, alumina particles are in situ formed by the displacement reaction between Al and ZnO. Some of the reduced Zn dissolves into the molten Al, while most of them vaporize at high temperature. It is found that the distribution of the alumina particles strongly depends on the rate of cooling of the sintered product. In comparison, the alumina particles are distributed more uniformly in the Al(Zn) solid solution matrix of the oil-quenched sample than that in the furnace-cooled sample. (C) 2003 Elsevier B.V. All rights reserved

Formation of MgO nanorods in the reaction zone of a Mg-CuO powder mixture by in-situ reaction

We report the in-situ formation of MgO nanorods during sintering of a Mg-20wt% CuO powder mixture at 450degreesC. After sintering, we identified three regions with distinct microstructures in the reaction zone between the Mg grain and the newly formed Cu grain. Region I contained MgO nanorods and Cu nanoparticles, region II was composed of MgO nanorods, while larger nanometre-sized MgO crystals were found in region III. The MgO nanorods were single crystals with a diameter of about 20 nm and a length of about 100 nm. The growth of these nanorods was controlled by the vapour-solid mechanism. The progressive change in morphology of the MgO phase had induced a hardness gradient across the reaction zone. As a result, the interfacial bonding between the major phases in the sintered product was enhanced

Formation of Al2Cu and AlCu intermetallics in Al(Cu) alloy matrix composites by reaction sintering

We report the fabrication and characterization of a series of Al(Cu) alloy-based matrix composites. The composites were produced by sintering and rapid quenching three powder mixtures of Al and Cu with hypoeutectic, eutectic, and hypereutectic compositions. The morphology of the reinforcements formed in the Al(Cu) matrices of these composites was found to be variable. A two-phase Al2Cu-Al(Cu) nanoeutectic, with lamellar spacing of 200-300 nm, was found in the Al(Cu) matrix of the sample having hypoeutectic composition after it was oil-quenched from 1000 degreesC to room temperature. While oil quenching the sample with eutectic composition, produced single Al2Cu Crystals of 2-2.5 mum size, embedded in a lamellar nanoeutectic matrix. As for the hypereutectic alloy, the matrix of the oil-quenched sample consisted mainly of Al2Cu intermetallic, and a secondary phase of AlCu dendrites with dendrite arms spacing of 1-1.5 mum. (C) 2004 Elsevier B.V All rights reserved

Formation of MgO and Mg-Zn intermetallics in an Mg-based composite by in situ reactions

The fabrication and microstructural characterization of an Mg-based metal matrix composite, which is reinforced by MgO ceramic and Mg-Zn intermetallics is described. The fabrication process involved the mixing and pressing of Mg and ZnO powders, and was followed by sintering of the green compact at a temperature below the melting point of Mg. The order of appearance of the in situ formed reinforcements, namely MgO and Zn-Mg eutectic, in the Mg matrix during sintering was investigated. Based on the Gibbs's free energy associated with each reaction, a model for the formation of this composite is postulated. (c) 2004 Elsevier Ltd. All rights reserved

Large-scale synthesis of aligned hexagonal ZnO nanorods using chemical vapor deposition

Aligned hexagonal ZnO nanorods were densely grown on a pure Si substrate. The synthesis involved a simple and low cost process based on thermal evaporation of ZnS powder, followed by oxidization without the presence of any catalyst. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and room-temperature cathodoluminescence (CL) spectroscopy. We found that the ZnO nanorods were pure, well-aligned, with diameters of 100-300 nm and length of about 10 mum. One strong green-light emission peak at 538 nn was observed. The origin of this cathodoluminescence might be ascribed to the existence of defects such as the single ionized oxygen vacancies formed in the ZnO nanorods. (C) 2004 Elsevier B.V. All rights reserved

Formation of micron-sized and nanometer-sized single crystal alumina whiskers by displacement reactions

We propose a general methodology for fabricating single crystal alpha-Al2O3 whiskers by displacement reactions. The methodology is based on studies in which Al-rich powder mixtures that contain different kinds of metal oxides (MOx) were sintered. In some sintered products, the in situ formed Al2O3 appeared as particulate while in other it appeared as whiskers. Some conclusions from this study are: growth of the whiskers involves the presence of MOx-1 vapor and Al2O vapor during sintering, and the dimension of the whiskers depends oil the size of the initial MO., particles. Micron-sized whiskers were produced in Al-MoO3 and in Al-WO3, while nanorods were produced ill Al-SiO2. (c) 2005 Elsevier Ltd. All rights reserved

The pandemic academy: Reflections of infectious diseases fellows during COVID-19

10.1093/ofid/ofaa256Open Forum Infectious Diseases77ofaa256