Hemoglobin A1c and C-reactive protein are independently associated with blunted nocturnal blood pressure dipping in obesity-related prediabetes.

Blunted nocturnal dipping in blood pressure (BP) is associated with increased cardiovascular disease (CVD) risk in middle-aged/older adults. The prevalence of blunted nocturnal BP dipping is higher in persons with obesity and diabetes, conditions that are also associated with elevated aortic stiffness and inflammation. Therefore, we hypothesized that elevated glycemia, inflammation and aortic stiffness would be inversely associated with the magnitude of nocturnal systolic BP dipping among middle-aged/older adults with obesity at high CVD risk. Twenty-four hour ambulatory BP monitoring, aortic stiffness (carotid-femoral pulse wave velocity, CF-PWV), hemoglobin A1c (HbA1c) and inflammation (C-reactive protein, CRP) were measured in 86 middle-aged/older adults with obesity and at least one other CVD risk factor (age 40-74 years; 34 male/52 female; body mass index=36.7±0.5 kg m-2; HbA1c=5.7±0.04%). In the entire cohort, CRP (ß=0.40±0.20, P=0.04), but not HbA1c or CF-PWV was independently associated with systolic BP dipping percent (Model R2=0.07, P=0.12). In stratified (that is, presence or absence of prediabetes) multiple linear regression analysis, HbA1c (ß=6.24±2.6, P=0.02) and CRP (ß=0.57±0.2, P=0.01), but not CF-PWV (ß=0.14± 2.6, P=0.74), were independently associated with systolic BP dipping percent (Model R2=0.32, P<0.01) in obese adults with prediabetes but were absent in obese adults without prediabetes (Model R2=0.01 P=0.95). However, nocturnal systolic BP dipping percent (P=0.65), CF-PWV (P=0.68) and CRP (P=0.59) were similar between participants with and without prediabetes. These data suggest that impaired long-term glycemic control and higher inflammation may contribute partly to blunted BP dipping in middle-aged/older adults with obesity-related prediabetes.

Interaction of the onset of spring and elevated atmospheric CO2 on ragweed (Ambrosia artemisiifolia L.) pollen production.

Increasing atmospheric carbon dioxide is responsible for climate changes that are having widespread effects on biological systems. One of the clearest changes is earlier onset of spring and lengthening of the growing season. We designed the present study to examine the interactive effects of timing of dormancy release of seeds with low and high atmospheric CO2 on biomass, reproduction, and phenology in ragweed plants (Ambrosia artemisiifolia L.), which produce highly allergenic pollen. We released ragweed seeds from dormancy at three 15-day intervals and grew plants in climate-controlled glass-houses at either ambient or 700-ppm CO2 concentrations, placing open-top bags over influorescences to capture pollen. Measurements of plant height and weight; inflorescence number, weight, and length; and days to anthesis and anthesis date were made on each plant, and whole-plant pollen productivity was estimated from an allometric-based model. Timing and CO2 interacted to influence pollen production. At ambient CO2 levels, the earlier cohort acquired a greater biomass, a higher average weight per inflorescence, and a larger number of influorescences; flowered earlier; and had 54.8% greater pollen production than did the latest cohort. At high CO2 levels, plants showed greater biomass and reproductive effort compared with those in ambient CO2 but only for later cohorts. In the early cohort, pollen production was similar under ambient and high CO2, but in the middle and late cohorts, high CO2 increased pollen production by 32% and 55%, respectively, compared with ambient CO2 levels. Overall, ragweed pollen production can be expected to increase significantly under predicted future climate conditions.