The effect of influenza vaccination on airway responsiveness in patients with stable asthma

Infection with influenza A virus causes exacerbations of asthma and increased airway responsiveness (AR). Annual vaccination is recommended. Live vaccines and some older killed vaccines caused increased AR. More recent studies using purified sub-unit vaccines suggest no effect on AR but some patients report exacerbations of asthma and there is reluctance to adhere to vaccination recommendations. There is therefore a need for further studies of the effect of current vaccines on AR and asthma control. We studied 22 subjects (mean age 41 (range 19-71) years; 8 male) with mild (FEV, > 60% predicted) stable asthma. All were taking inhaled β agonists and 20, inhaled steroids; 13 had previously had influenza vaccination. Subjects were randomized to receive placebo (n = 5) or inactivated surface antigen vaccine (Evans Ltd) (n=17). They kept records of asthma symptoms, medication used and adverse events. FEV and AR (as the dose of methacholine provoking a 20% fall in FEV : PD) were measured twice before vaccination and at 48 and 96 hours post vaccination. There was no significant difference in pre and post vaccination FEV or AR in either the placebo or vaccinated groups: mean FEV changed from 2.9L pre vaccine to 2.83 and 2.9L, 48 and 96 hours post vaccine; mean PD changed from 120μg pre vaccine to 102 and 101 μg, 48 and 96 hours post vaccine. No subject showed a significant fall in FEV or PD, or had a change in asthma symptoms or medication; 7 of those given vaccine had fever and malaise, and one had a local reaction. We conclude that inactivated surface antigen vaccine does not generally exert any adverse effect on asthma

Formate species in the low-temperature oxidation of dimethyl ether

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The comparative and combined effects of nitric oxide and higher alkanes in sensitizing methane oxidation

The comparative and combined effects of nitric oxide (NO) and higher alkanes on methane oxidation were examined by experimentation and kinetic modeling. Experiments were conducted using fuel-lean, lower-alkanes mixtures with NO (0–400 ppm v/v) in an atmospheric flow reactor at residence time of 2 s over the temperature range of 820–950 K. NO was found to greatly promote methane conversion, and its sensitizing effect strengthened with the increasing concentration that was added to the system. The promoting effect of higher alkanes on methane conversion was also evident, particularly at zero or low NO concentrations. A strong dependency of the sensitizing effect on the concentration of higher alkanes present was also observed. The kinetic mechanism from Le Cong et al., performed reasonably well in reproducing the experimental trends. However, the sensitizing propensity of higher alkanes in the presence of NO could not be unambiguously ranked under all conditions. Modification to the kinetic mechanism of Le Cong et al., was attempted. Specifically, the submechanism of C3 peroxy radicals was added, but the modeling results indicated a lower impact on methane conversion than was initially expected. The most sensitive reactions were revealed, and the generalized reaction pathways for methane oxidation sensitized by higher alkanes, with or without the presence of NO, were also proposed, following detailed sensitivity analysis