Measurement of plasma renin activity with use of HPLC-electrospray-tandem mass spectrometry

Background:;The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA). Methods: After incubation (37 degrees C for 3 or 18 h), samples were prepared using C-18 solid-phase extraction. [Val](5)Ang1 was used as the internal standard (IS). Chromatography was performed on a C-18 column, using 200 mL/L ammonium acetate buffer-800 mL/L methanol as the mobile phase. The flow rate was 150 mu L/min, with a chromatographic run time of 5 min/sample. Mass spectrometric detection was in the positive ionization mode with selected reaction monitoring (Ang1 mit 649.0-->784.0; IS mit 641.9-->770.4). Results: The assay was linear over the range 2.5-500 ng Angl/mL, which corresponded to a limit of detection (signal-to-noise ratio of 3:1) of PRA of 0.14 ng Ang1 mL(-1) h(-1). The imprecision (CV) of the assay at PRA values of 26.1, 13.5, 3.2 and 0.78 ng Ang1 mL(-1) h(-1) was 7.0%, 7.0%, 15%, and 11%, respectively. Absolute recoveries were 92.3% (Ang1) and 87.4% (IS). Incubation times of 3 h vs 18 h in the PRA assay gave good agreement at PR

A longitudinal study of the impacts of an annual event on local residents

Understanding the impact of an event on residents' quality of life (QOL) is becoming increasingly important because local residents are the key source of attendees for most events and help ensure the event's survival. This study compares the host community perceptions of the impacts of the Australian Formula 1 Grand Prix over time to determine whether there were changes in resident perceptions of the event's influence on residents' QOL. The same methods were used in each of two separate data collection phases spaced three years apart. Using postal surveys, 279 responses were received each year, although these represented different response rates. Cluster analysis was used to identify residents with varying perceptions. The findings suggest that, over time, the number of respondents in the "unconcerned" category had grown and those with extreme positive and negative perceptions had decreased. The respondents to Phase 2 of the study had an increased appreciation of the economic contribution of the event and the impact on residents' QOL appeared to be less damaging, with fewer concerns about noise and the operational components of the event in the latter cohort. The paper concludes with a discussion of the implications for event organisers and local tourism authorities in managing events for improved residents' QOL