Exercise-Induced Alterations in Phospholipid Hydrolysis, Airway Surfactant and Eicosanoids and their Role in Airway Hyperresponsiveness in Asthma

The mechanisms responsible for driving endogenous airway hyperresponsiveness (AHR) in the form of exercise-induced bronchoconstriction (EIB) are not fully understood. We examined alterations in airway phospholipid hydrolysis, surfactant degradation, and lipid mediator release in relation to AHR severity and changes induced by exercise challenge. Paired induced sputum (n=18) and bronchoalveolar lavage (BAL) fluid (n=11) were obtained before and after exercise challenge in asthmatic subjects. Samples were analyzed for phospholipid structure, surfactant function and levels of eicosanoid and secreted phospholipase A2 group 10 (sPLA2-X). A primary epithelial cell culture model was used to model effects of osmotic stress on sPLA2-X. Exercise challenge resulted in increased surfactant degradation, phospholipase activity, and eicosanoid production in sputum samples of all patients. Subjects with EIB had higher levels of surfactant degradation and phospholipase activity in BAL fluid. Higher basal sputum levels of cysteinyl leukotrienes (CysLTs) and prostaglandin D2 (PGD2) were associated with direct AHR and both the post-exercise and absolute change in CysLTs and PGD2 levels were associated with EIB severity. Surfactant function was either abnormal at baseline or became abnormal after exercise challenge. Baseline levels of sPLA2-X in sputum and the absolute change in amount of sPLA2-X with exercise were positively correlated with EIB severity. Osmotic stress ex vivo resulted in movement of water and release of sPLA2-X to the apical surface. In summary, exercise challenge promotes changes in phospholipid structure and eicosanoid release in asthma, providing two mechanisms that promote bronchoconstriction, particularly in individuals with EIB who have higher basal levels phospholipid turnover.

Vermicompost for Mitigation of Surfactant Contamination in Surface Water

Surfactants are the most important pollutants of surface water which should be removed for the safety of aquatic life. The potentiality of vermicompost for the removal of surfactant contamination in surface water was studied by measuring surfactant concentration, pH and conductivity for nine days in six trials with different proportions of soil, vermicompost and phosphate keeping the surfactant concentration constant. The trials T1, T2, T3, T4 and T5 were considered as simulated ponds and T0 as control. The surfactant concentration, electrical conductivity and pH were found to change upon the application of vermicompost. The surfactant degradation rate of vermicompost amended systems was significantly higher than the control system. Surfactant was almost completely depleted in vermicompost amended systems within the monitoring period. The presence of phosphate increases the surfactant removal efficacy of vermicompost. The pH values for vermicompost amended systems were almost constant near 7. The electrical conductivity of vermicompost amended systems was found to increase with time whereas that for the control systems was almost constant. Therefore, vermicompost can be considered as an excellent amendment as they have the ability to remove surfactant in surface water correcting the pH and increasing the availability of nutrients of the systems.

Oil Solubilization Using Surfactant for Biohydrogen Production

Oily wastewater is a potential source for biohydrogen production due to its high organic content. Incorporation of surfactant could enhance the solubilization of oil in water, and thus increase its biodegradability. The first part of this work studied the influence of surfactant concentrations (0-240 CMC) and temperatures (28-70 °C) on oil solubilization in aqueous solution. Results from batch tests showed that the oil solubilization improved as the surfactant concentration increased up to 100 CMC. As high as 0.002 mg/L oil concentration could be solubilized at 1 CMC and 55 °C, which was 90 times higher than that obtained without surfactant application. Moreover, the time to reach oil-in-liquid equilibrium could be shortened by increasing the temperature. In the second part, the effect of surfactant addition on hydrogen production was investigated at pH 5.5 and 55 °C. In 148 h batch assays, the highest hydrogen production observed was 19.3 mL at 1 CMC while it was 8.7 mL at no surfactant. Further investigation at 1 CMC revealed that surfactant degradation to H2 was 2.36 mL, thus the effect of surfactant to enhance oil degradability was 0.24 L H2 per liter of aqueous solution under excess oil condition.

Evaluation of Efficacy of Anionic Surfactant Degradation in the Presence of Concomitant Impurities of Natural Waters

The efficacy of anionic surfactant—sodium alkylbenzene sulfonate (ABS) degradation in the river waters and model solutions containing humic acid by various oxidation processes has been compared. The most effective method is photocatalytic ozonation (O3/TiO2/UV) which ensures maximum reduction of ABS concentration (94%-95% over 20–30 min) from ~5 mg/dm3to values not exceeding the MPC (<0.5 mg/dm3) and the highest degree of total organic carbon (TOC) removal (up to 74%) at the lowest values of specific ozone consumption per 1 mg/dm3of TOC compared to ozonation and O3/UV. Photocatalytic oxidation with air oxygen (O2/TiO2/UV) and O3/UV treatment provides a smaller decrease in ABS concentrations (86%–93% and 71%–87% within 20–30 min, resp.) and significantly lowers TOC removal (up to 57% and 47%, resp.). Ozonation and UV irradiation, used separately, are inefficient methods for ABS degradation (<40%), and for TOC removal (<15%).