Craig M. Zelig

The effect of magnesium sulfate on the activity of matrix metalloproteinase-9 in fetal cord plasma and human umbilical vein endothelial cells

OBJECTIVE Clinical evidence suggests that magnesium sulfate may reduce the risk of fetal neurologic injury in preterm delivery. Matrix metalloproteinase-9 (MMP-9) levels are elevated in preterm labor patients. There is evidence that MMP-9 may break down the blood-brain barrier in humans, causing cytokine mediated cell injury. Our objective was to determine whether the addition of magnesium sulfate attenuates activity of MMP-9, a complex zinc-dependent enzyme, in fetal cord plasma. STUDY DESIGN We collected cord plasma in 6 term, unlabored patients. Using enzyme-linked immunosorbent assay, we measured the activity of MMP-9 with varying concentrations of magnesium sulfate added in vitro. Results were verified using a human umbilical cord vein endothelial cell (HUVEC) line. RESULTS Addition of physiologic doses of magnesium sulfate (0.07 mg/mL) resulted in a 25% decrease in active MMP-9 (P = .03). In a HUVEC line, magnesium sulfate resulted in a 32% decrease in MMP-9 activity (P = .00012). CONCLUSION The addition of magnesium sulfate attenuated MMP-9 activity in cord plasma and in a HUVEC line.

Interaction between maternal obesity and Bishop score in predicting successful induction of labor in term, nulliparous patients.

OBJECTIVE Determine the Bishop score most predictive of induction of labor (IOL) success for different maternal weight groups. STUDY DESIGN Retrospective cohort study. Prospectively collected database utilized to determine the optimum Bishop score within each prepregnancy body mass index (BMI) category of term, nulliparous patients undergoing IOL. RESULTS For the total group (n = 696), Bishop score ≥ 5 was most predictive of success (75% versus 56%, p < 0.0001). Within each BMI category, Bishop score ≥ 5 remained most predictive: normal weight (79% versus 64%, p < 0.01); overweight (72% versus 58%, p = 0.03); and obese (73% versus 45%, p < 0.0001). Overall, nonobese patients had more success than obese patients (70% versus 59%, p < 0.01). The nonobese group had more success than the obese group when the Bishop score was < 3 (57% versus 39%, p < 0.05) but not when it was ≥ 3 (72% versus 65%, p = 0.1). Also, there was a higher fraction of patients with Bishop score < 3 in the obese group compared with the nonobese group (25% versus 14%, p < 0.001). CONCLUSION The optimum Bishop score for predicting successful IOL in nulliparous patients was 5 regardless of BMI class. The higher IOL failure rate observed in obese women was associated with lower starting Bishop scores and was compounded by higher failure rates in obese women with Bishop scores < 3.

Continuous infusion of 17-hydroxyprogesterone caproate into either the fetoplacental or intervillous circulation of a placental cotyledon attenuates vasoconstriction of the fetoplacental arteries by thromboxane mimetic U46619.

OBJECTIVE The objective of the study was to determine whether pretreatment of fetal or maternal placental vasculature with 17-hydroxyprogesterone caproate (17-P) attenuates the vasoactive effect of the thromboxane mimetic U46619. STUDY DESIGN Two cotyledons were obtained from each placenta studied. For the first 5 placentas, the fetal artery of 1 cotyledon from each pair was infused with 17-P. After 30 minutes, a bolus dose of U46619 was administered to both cotyledons. An identical procedure was carried out on the next 5 placentas except that 17-P was infused into the intervillous space. RESULTS The pressure excursion caused by bolus administration of U46619 was less in the cotyledons infused with 17-P, both in the 5 cases in which the fetal vasculature was infused with 17-P (P = .0035) and in the 5 cases in which the maternal vasculature was infused with 17-P (P = .038). CONCLUSION Pretreatment of either the fetal or maternal circuits of the placenta with 17-P attenuates U46619-mediated fetoplacental vasoconstriction.