Inhaled steroid/tobacco smoke particle interactions: a new light on steroid resistance

<p>Abstract</p> <p>Background</p> <p>Inhaled steroid resistance is an obstacle to asthma control in asthmatic smokers. The reasons of this phenomenon are not yet entirely understood. Interaction of drug particles with environmental tobacco smoke (ETS) could change the aerodynamic profile of the drug through the particle coagulation phenomenon. Aim of the present study was to examine whether steroid particles interact with smoke when delivered in the presence of ETS.</p> <p>Methods</p> <p>Beclomethasone-hydrofluoralkane (BDP-HFA) pMDI particle profile was studied after a single actuation delivered in ambient air or in the presence of ETS in an experimental chamber using a light scattering Optical Particle Counter capable of measuring the concentrations of particle sized 0.3–1.0, 1.1–2.0, 2.1–3.0, 3.1–4.0, 4.1–5.0, and > 5.1 μm in diameter with a sampling time of one second. The number of drug particles delivered after a single actuation was measured as the difference between total particle number after drug delivery and background particle number. Two groups of experiments were carried out at different ambient background particle concentrations. Two-tail Student's t-test was used for statistical analysis.</p> <p>Results</p> <p>When delivered in ambient air, over 90% of BDP-HFA particles were found in the 0.3–1.0 μm size class, while particles sized 1.1–2.0 μm and 2.1–3.0 represented less than 6.6% and 2.8% of total particles, respectively. However, when delivered in the presence of ETS, drug particle profile was modified, with an impressive decrease of 0.3–1.0 μm particles, the most represented particles resulting those sized 1.1–2.0 μm (over 66.6% of total particles), and 2.1–3.0 μm particles accounting up to 31% of total particles.</p> <p>Conclusion</p> <p>Our data suggest that particle interaction between inhaled BDP-HFA pMDI and ETS takes place in the first few seconds after drug delivery, with a decrease in smaller particles and a concurrent increase of larger particles. The resulting changes in aerosol particle profile might modify regional drug deposition with potential detriment to drug efficacy, and represent a new element of steroid resistance in smokers. Although the present study does not provide any functional or clinical assessment, it might be useful to advise smokers and non smokers with obstructive lung disease such as asthma or COPD, to avoid to act inhaled drugs in the presence of ETS in order to obtain the best therapeutic effect.</p

A comparative process study of chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) for solid fuels

A solid-fuel combustion system based on chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) has the potential to assist in the capture of CO2 from coal-fired power plants. In both processes an air separation unit is not required, and the flue gas streams from CLC and CLOU contain primarily carbon dioxide and water, which facilitates CO2 capture. CLOU offers a potential advantage for solid fuels as it uses combustion reactions. The O-2 for the combustion reactions in CLOU is supplied from the reduction of a metal oxide (e.g. CuO). Iron-based materials are being considered for oxygen carriers in CLC, wherein the coal is gasified, and subsequently the product gas is oxidized to CO2 and H2O by reaction with the circulating oxygen carrier. CLOU affords faster coal char oxidation reaction rates, as compared to CLC coal gasification reactions, but CuO-based materials for CLOU will necessarily be more expensive. Furthermore, the stability of CuO-based oxygen carrier materials is also an important concern. In this paper, ASPEN PLUS process engineering models were developed for combustion of a Wyoming Powder River Basin coal using an iron-based oxygen carrier for CLC and a copper-based oxygen carrier for CLOU. The objective of these process models was to evaluate the material and energy requirements for a process development unit by incorporating insights from previously reported kinetic studies on laboratory scale units. A relative economic analysis has also been performed to address key technical challenges which will subsequently help in addressing the development of CLC and CLOU for solid fuels. Due to slower char gasification reaction times, CLC requires a larger reactor, which results in a relatively higher capital cost. It also manifests in a higher pressure drop and consequently higher energy costs for fluidizing the oxygen carrier. (C) 2014 Elsevier Ltd. All rights reserved.22237243Department of Energy [DE-NT0005015]Department of Energy [DE-NT0005015