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The objective of the current research was to develop a liquid chromatography-MSn (LC-MSn) methodology for the determination of free cortisol and its 15 endogenous metabolites (6β-hydroxycortisol, 20α-dihydrocortisol, 20α-dihydrocortisone, 20-β-dihydrocortisol, 20β-dihydrocortisone, prednisolone, cortisone, α-cortolone, β-cortolone, allotetrahydrocortisol, 5α-dihydrocortisol, tetrahydrocortisol, allotetrahydrocortisone, 5β-dihydrocortisol, tetrahydrocortisone) in human urine. Due to its optimal performance, a linear ion trap operating in ESI negative ion mode was chosen for the spectrometric analysis, performing MS3 and MS4 experiments. The method was validated for limit of detection (LOD) and limit of quantification (LOQ) (0.01 ng mL−1 and 0.05 ng mL−1, for all compounds, respectively), intra- and inter-day precision (CV = 1.4–9.2% and CV = 3.6–10.4%, respectively), intra- and inter-day accuracy (95–110%), extraction recovery (65–95%), linearity (R2 > 0.995), and matrix effect that was absent for all molecules. Additionally, for each compound, the percentage of glucuronated conjugates was estimated. The method was successfully applied to the urine (2 mL) of 50 healthy subjects (25 males, 25 females). It was also successfully employed on urine samples of two patients with Cushing syndrome and one with Addison's disease. This analytical approach could be more appropriate than commonly used determination of urinary free cortisol collected in 24-h urine. The possibility of considering the differences and relationship between cortisol and its metabolites allows analytical problems related to quantitative analysis of cortisol alone to be overcome. Furthermore, the developed method has been demonstrated as efficient for antidoping control regarding the potential abuse of corticosteroids, which could interfere with the cortisol metabolism, due to negative feedback on the hypothalamus-hypophysis-adrenal axis. Lastly, this method was found to be suitable for the follow-up of prednisolone that was particularly important considering its pseudo-endogenous origin and correlation with cortisol metabolism. [ABSTRACT FROM AUTHOR]

It is increasingly being recognized that effective communications are key to a successful response to emergency and disaster situations. The ability of the first responder emergency services to communicate among themselves and to share multimedia information directly affects the ability to save lives. This is reflected in increasing public investment in broadband public safety communication systems. These systems have some specific requirements, which are outlined in this article. As LTE is expected to become the most widely deployed broadband communication technology, we examine the capability of LTE to meet these requirements, and identify possible future developments to LTE that could further enhance its ability to provide the necessary service. [ABSTRACT FROM PUBLISHER]