Redox and electrophilic properties of vapor- and particle-phase components of ambient aerosols.

Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semi-volatile components may also contribute to many adverse health effects.

Determination of metal-based hydroxyl radical generating capacity of ambient and diesel exhaust particles.

Numerous studies have suggested the association of reactive oxygen species (ROS) with adverse health effects derived from exposure to airborne particulate matter (PM) and diesel exhaust particles (DEP). This redox activity has been attributed to both inorganic and organic species present in these particles, but a clear distinction has not been established between the contribution of each. This article describes an application of an analytical procedure, based on the reaction of salicylic acid with hydroxyl radical to form dihydroxybenzoate (DHBA) isomers, to measure transition metal-based redox activity associated with ambient and diesel exhaust particles.

Testosterone metabolic clearance and production rates determined by stable isotope dilution/tandem mass spectrometry in normal men: influence of ethnicity and age.

The metabolic clearance rate (MCRT) and production rate (PRT) of testosterone (T) were measured using constant infusion of trideuterated (d3) T and quantitating serum d3T by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Serum unlabeled T (d0T) was measured by LC-MS-MS, and serum total T (d3T + d0T) was measured by RIA. Mean MCRR (measured by LC-MS-MS) in young white men (1272 +/- 168 liters/d) was not significantly different from young Asian men (1070 +/- 166 liters/d).