Air pollution, weight loss and metabolic benefits of bariatric surgery: a potential model for study of metabolic effects of environmental exposures.

BACKGROUND: Emerging experimental evidence suggests that air pollution may contribute to development of obesity and diabetes, but studies of children are limited. OBJECTIVES: We hypothesized that pollution effects would be magnified after bariatric surgery for treatment of obesity, reducing benefits of surgery. METHODS: In 75 obese adolescents, excess weight loss (EWL), high-density lipoprotein (HDL) cholesterol, triglycerides, alkaline phosphatase (ALP) and hemoglobin A1c (HbA1c ) were measured prospectively at baseline and following laparoscopic adjustable gastric banding (LAGB). Residential distances to major roads and the average two-year follow-up exposure to particulate matter <2.5 µm (PM2.5 ), nitrogen dioxide (NO2 ) and ozone were estimated. Associations of exposure with change in outcome and with attained outcome two years post-surgery were examined. RESULTS: Major-roadway proximity was associated with reduced EWL and less improvement in lipid profile and ALP after surgery. NO2 was associated with less improvement in HbA1c and lower attained HDL levels and change in triglycerides over two years post-surgery. PM2.5 was associated with reduced EWL and reduced beneficial change or attained levels for all outcomes except HbA1c . CONCLUSIONS: Near-roadway, PM2.5 and NO2 exposures at levels common in developed countries were associated with reduced EWL and metabolic benefits of LAGB. This novel approach provides a model for investigating metabolic effects of other exposures.

Orbitally induced oscillations in the East Antarctic ice sheet at the Oligocene/Miocene boundary.

Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3-4 degrees C warmer than at present and atmospheric CO2 concentrations were twice as high as today, the Antarctic ice sheets may have been unstable. Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles. But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets. Here we present sediment data from shallow marine cores in the western Ross Sea that exhibit well dated cyclic variations, and which link the extent of the East Antarctic ice sheet directly to orbital cycles during the Oligocene/Miocene transition (24.1-23.7 Myr ago). Three rapidly deposited glacimarine sequences are constrained to a period of less than 450 kyr by our age model, suggesting that orbital influences at the frequencies of obliquity (40 kyr) and eccentricity (125 kyr) controlled the oscillations of the ice margin at that time. An erosional hiatus covering 250 kyr provides direct evidence for a major episode of global cooling and ice-sheet expansion about 23.7 Myr ago, which had previously been inferred from oxygen isotope data (Mi1 event).