RESUMO
OBJECTIVE: To identify a reference range for placental growth factor (PlGF) in normotensive women without symptoms or signs of preeclampsia. STUDY DESIGN: Comprising the study cohort were 247 term pregnancies without preeclampsia or adverse neonatal outcomes from 16 sites in the US and Canada. Serial plasma samples were collected in 6 gestational age (GA) intervals between 20+0 and 40+0weeks. Non-parametric percentiles of the distribution of PlGF were estimated in each GA interval and a parametric model was developed to describe the distribution of PlGF as a continuous smooth function of GA (from 20 to 40weeks) in normal healthy pregnancy. Demographic and clinical factors influencing PlGF levels were also examined. RESULTS: There were 1366 evaluable samples collected from 247 subjects (242, 238, 226, 223, 222, and 215 samples in each GA interval, 20-24, 24-29, 29-32, 32-35, 35-37, and 37-40weeks, respectively). The 5th percentile of PlGF was 76.4, 141.1, 139.3, 65.5, 31.7, and 23.4pg/mL in each respective GA interval. The distribution of PlGF is approximately log normal with parameters that vary continuously as a function of GA. PlGF distribution is weakly dependent on maternal age, race/ethnicity, parity, and maximum systolic blood pressure (taken between weeks 20 and 24). Although statistically significant, these factors did not modify PlGF levels by more than ±15%. CONCLUSION: These data provide a valid reference range for PlGF in normal pregnancy.
RESUMO
Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.
