Percentiles of intrauterine placental volume and placental volume relative to fetal volume: A prospective magnetic resonance imaging study.

INTRODUCTION: We aimed to provide percentiles of intrauterine placental growth and placental growth relative to fetal growth (placental to fetal ratio) by measuring placental and fetal volumes by magnetic resonance imaging (MRI). METHODS: In this prospective study, 107 unselected singleton pregnancies were examined by MRI at gestational week 27 and 37. Based on the estimated volumes of the placenta and the fetus, we calculated median and percentiles at gestational weeks 27 and 37. RESULTS: Median placental volume at gestational week 27 was 513 cm3 (Inter Quartile Range (IQR) 182 cm3), and 831 cm3 (IQR 252 cm3) at week 37. The 10th - 90th percentiles included placental volumes between 392 and 717 cm3 at gestational week 27, and 631-1087 cm3 at week 37. The placental to fetal ratio was significantly higher at gestational week 27 than at week 37, with a median ratio of 0.54 (IQR 0.18) and 0.31 (IQR 0.08), respectively (p < 0.001). The 10th-90th percentiles included placental to fetal ratios between 0.43 and 0.73 at gestational week 27 and 0.25-0.39 at week 37. DISCUSSION: At gestational week 27, the placental volume was about half the size of the fetal volume, whereas at week 37, the placental volume was about one third of the fetal volume. This finding suggests that placental growth was less prominent than fetal growth after gestational week 27. Knowledge about the distribution of intrauterine placental size in the general population of pregnancies are prerequisites for diagnosing abnormal placental size.

IL-18 neutralization during alveolar hypoxia improves left ventricular diastolic function in mice.

AIM: In patients, an association exists between pulmonary diseases and diastolic dysfunction of the left ventricle (LV). We have previously shown that alveolar hypoxia in mice induces LV diastolic dysfunction and that mice exposed to hypoxia have increased levels of circulating interleukin-18 (IL-18), suggesting involvement of IL-18 in development of diastolic dysfunction. IL-18 binding protein (IL-18BP) is a natural inhibitor of IL-18. In this study, we hypothesized that neutralization of IL-18 during alveolar hypoxia would improve LV diastolic function. METHODS: Mice were exposed to 10% oxygen for 2 weeks while treated with IL-18BP or vehicle. Cardiac function and morphology were measured using echocardiography, intraventricular pressure measurements and magnetic resonance imaging (MRI). For characterization of molecular changes in the heart, both real-time PCR and Western blotting were performed. ELISA technique was used to measure levels of circulating cytokines. RESULTS: As expected, exposure to hypoxia-induced LV diastolic dysfunction, as shown by prolonged time constant of isovolumic relaxation (τ). Improved relaxation with IL-18BP treatment was demonstrated by a significant reduction towards control τ values. Decreased levels of phosphorylated phospholamban (P-PLB) in hypoxia, but normalization by IL-18BP treatment suggest a role for IL-18 in regulation of calcium-handling proteins in hypoxia-induced diastolic dysfunction. In addition, MRI showed less increase in right ventricular (RV) wall thickness in IL-18BP-treated animals exposed to hypoxia, indicating an effect on RV hypertrophy. CONCLUSION: Neutralization of IL-18 during alveolar hypoxia improves LV diastolic function and partly prevents RV hypertrophy.