Respiratory impairment of older persons: when less means more

BACKGROUND: Among older persons, within the clinical context of respiratory symptoms and mobility, evidence suggests that improvements are warranted regarding the current approach for identifying respiratory impairment (i.e., a reduction in pulmonary function). METHODS: Among 3,583 white participants aged 65–80 (Cardiovascular Health Study), we calculated the prevalence of respiratory impairment using the current spirometric standard from the Global Initiative for Obstructive Lung Disease (GOLD) and an alternative spirometric approach termed Lambda-Mu-Sigma (LMS). Results for GOLD- and LMS-defined respiratory impairment were evaluated for their (cross-sectional) association with respiratory symptoms and gait speed, and also for the 5-year cumulative incidence probability of mobility disability. RESULTS: The prevalence of respiratory impairment was 49.7% (1,780/3,583) when using GOLD and 23.2% (831/3,583) when using LMS. Differences in prevalence were most evident among participants who had no respiratory symptoms, with respiratory impairment classified more often by GOLD (38.1% [326/855]) than LMS (12.3% [105/855]); as well as among participants who had normal gait speed, with respiratory impairment classified more often by GOLD (46.4% [1,003/2,164]) than LMS (19.3% [417/2,164]). Conversely, the 5-year cumulative incidence probability of mobility disability for respiratory impairment was higher for LMS than GOLD (0.313 and 0.249 for never-smokers, and 0.352 and 0.289 for ever-smokers, respectively), but was similar for normal spirometry by LMS or GOLD (0.193 and 0.185 for never-smokers, and 0.219 and 0.216 for ever-smokers, respectively). CONCLUSION: Among older persons, the LMS approach (versus the GOLD approach) classifies respiratory impairment less frequently in those who are asymptomatic, and is also more strongly associated with mobility disability

Characterization of suboxic groundwater colloids using a multi-method approach

Anoxic groundwater colloid properties were measured using a minimally perturbing procedure for sampling, sample preparation and analysis. Analytical methods included atomic force microscopy (AFM), flow field flow fractionation (FlFFF), transmission and scanning electron microscopy (TEM and SEM). Shallow groundwater samples were found to have abundant iron rich nanoparticles (NP) with diameters of 10-30 nm as well as a smaller heterogeneous polydisperse dissolved organic matter (DOM) fraction. AFM results showed NP with average heights of 10 ± 2 nm, which was corroborated by high resolution (HR) TEM and SEM. FlFFF with UV254 nm detection showed particles with number average diffusion coefficients of 2-3 × 10^-10 m^2 s^-1 and hydrodynamic diameters between 1.5-2 nm, probably representing smaller organic macromolecules. Aeration of the samples resulted in extensive agglomeration of NP to form larger (>50 nm) colloids, and the reduction of UV-absorbing material detected in the 0.5-4 nm range. The complementary methods described have potential applications for investigating the fate and transport of NP in suboxic hotspots such as leachate plumes, waste water treatment plants and within the hyporheic mixing zone