Publications

Exposure to air polluted with particles less than 2.5 micron in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18 to 20 hr after inhalation of fine and ultrafine magnesium oxide particles produced from a furnace system model. We compared postexposure studies with control studies from the same six subjects. Mean +/- standard deviation (SD) cumulative magnesium dose was 4,138 +/- 2,163 min x mg/m3. By weight, 28% of fume particles were ultrafine (<0.1 micron in diameter) and over 98% of fume particles were fine (<2.5 micron in diameter). There were no significant differences in BAL inflammatory cell concentrations, BAL interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor, pulmonary function, or peripheral blood neutrophil concentrations postexposure compared with control. Our findings suggest that high-dose fine and ultrafine magnesium oxide particle exposure does not produce a measurable pulmonary inflammatory response. These findings are in marked contrast with the well-described pulmonary inflammatory response following zinc oxide particle inhalation. We conclude that fine and ultrafine particle inhalation does not result in toxicity in a generic manner independent of particle composition. Our findings support the concept that particle chemical composition, in addition to particle size, is an important determinant of respiratory effects.

OBJECTIVES

We sought to determine prospectively the prevalence, evolution and embolic risk of valve excrescences in normal subjects and patients with and without suspected cardioembolism.

BACKGROUND

Valve excrescences detected by transesophageal echocardiography (TEE) have been considered a cardioembolic substrate in selected patients.

METHODS

Ninety healthy volunteers (Group I) and 88 patients without suspected cardioembolism and a normal TEE (Group II) were studied and followed up clinically for 58 +/- 21 and 48 +/- 20 months, respectively. To assess the evolution of valve excrescences, 45 of these subjects underwent repeat TEE at 31 +/- 13 months. The findings in Groups I and II were compared with those of Group III--49 patients referred for TEE for suspected cardioembolism.

RESULTS

Valve excrescences were detected in 34 subjects (38%) in Group I and in 41 patients (47%) in Group II. In Group III, 20 patients (41%) had excrescences, but 85% of them had other potential cardiac or vascular sources of embolism. In all groups, mitral valve excrescences were predominant (68% to 76%), followed by aortic (38% to 50%) and right-sided valves (<10%). Excrescences were equally frequent in men and women and between all age groups studied. During follow-up in Groups I and II, excrescences persisted unchanged, and 1 (1.4%) of 74 patients with and 2 (2%) of 99 subjects without excrescences had cerebral ischemic events (80% power to detect a clinically meaningful difference of 4%).

CONCLUSIONS

Valve excrescences are common on the left-sided heart valves of normal subjects and patients regardless of gender and age; they persist unchanged over time and do not appear to be a primary source of cardioembolism.