Carlyle Crenshaw

Biophysics of the developing heart: III. A comparison of the left ventricular dynamics of the fetal and neonatal lamb heart

Changes in heart rate, left ventricular dimensions, and inotropic state of chronically instrumented lambs from in utero to neonatal life are described and analyzed. Six lambs were instrumented from 5 to 23 days prior to parturition and studied prior to and after birth. Heart rate, aortic systolic and diastolic pressure, left ventricular end-diastolic and peak systolic pressure, and left ventricular minor axis end-diastolic (EDD) and end-systolic dimension (ESD) were monitored. The maximum rate of rise of left ventricular pressure (Pmax), percentage fractional shortening [(EDD - ESD divided by EDD) x 100%; %FS], and the Pmax -interval ratio (this ratio of Pmax of the postextrasystolic potentiated systole to Pmax of the previous regular systole is independent of volume) described contractility. Subsequent to birth: heart rate, aortic systolic and diastolic pressure and left ventricular dimensions increased; during spontaneous rhythm and at equal fetal and neonatal heart rates and ventricular dimensions, %FS and P max increased significantly; and P max -interval ratio changed significantly. An increase in myocardial inotropic state occurs with birth. This enhancement is in addition to the effects of the increase in heart rate and end-diastolic volume that occur with the adaptation to birth.

Effect of exogenous dehydroepiandrosterone upon the fetoplacental biosynthesis of estrogens and its effect upon uterine blood flow in the term pregnant ewe

The fetoplacental unit of the ewe is capable of increasing the biosynthesis of estrogens following the exogenous administration of DHEA to the fetus. The maximum concentrations of estrogens appeared approximately 30 minutes after the administration of DHEA. Uterine blood flow in the pregnant ewe increased approximately 90 minutes after the maximum concentrations of estrogens were noted. The administration of DHEA to the nonpregnant, ovariectomized ewe did not elicit estrogen biosynthesis or changes in uterine blood flow. Isotope experiments in the pregnant ewe demonstrated the incorporation of DHEA into urinary estradiol.

Premature labor and premature rupture of the membranes

Abstract The effects of prolonged rupture of membranes upon the outcome of the mother and the fetus remain a problem in obstetrics. In an attempt to correlate the time interval between premature rupture of the membranes (PROM) and the onset of labor prior to term and maternal and perinatal outcome, a retrospective study was done in patients admitted to the Duke University Medical Center during the 5 year interval 1971 to 1975. Of these patients, 184 had premature labor prior to the rupture of membranes and 151 had PROM. A total of 335 pregnant patients who bore infants weighing from 1,000 to 2,500 grams were studied. Only infants of appropriate weight for their gestational age at birth and without apparent fetal malformations were included in the study. The time interval between rupture of membranes and onset of labor and delivery ranged from 0 hours to 4 weeks. All the patients were divided into three groups according to birth weight. For each group with PROM, the length of time of rupture of membranes prior to labor was compared with the development of neonatal respiratory distress syndrome (RDS) and maternal and neonatal infections. Infants from mothers with premature labor only were used as a reference group. Statistically, the data demonstrated a decrease in RDS in infants weighing from 1,000 to 1,500 grams with an increase in duration of rupture of membranes. This incidence of RDS was not altered when birth weight was above 1,500 grams. The development of fetal pulmonary maturity and the effect of time in relationship to the development of maternal and fetal infections and a possible time for delivery following PROM are discussed.

Acute fatty metamorphosis of the liver: A report of two patients who survived

Two patients with acute fatty metamorphosis of the liver of pregnancy who survived are presented. Clinical and pathologic features, possible etiologic factors, and principles of treatment are discussed. Both patients subsequently were allowed to become pregnant again, both had uncomplicated second pregnancies without evidence of liver disease, and both delivered healthy babies.

Serotonin studies in abnormal pregnancies: A preliminary report

Abstract In this preliminary report, serotonin levels in whole blood and urinary excretion products of serotonin (5-hydroxyindoleacetic acid) have been measured in 150 patients with vascular abnormalities in late pregnancy, and in 59 normal pregnant patients who served as controls. Determinations were made ante partum, on the day of delivery, and post partum. The data suggest that some patients with the toxemias of pregnancy, hypertensive vascular disease, and acute bleeding disorders of late pregnancy have high levels of serotonin. Whether this reflects an increased production or an altered detoxification or excretion is unknown.

Whole and Disaturated Lung Phosphatidylcholine in Cortisol-Treated, Intrauterine Growth-Retarded and Twin Control Lambs at Different Gestational Ages

Lambs 116--124 days gestation infused in utero for 75 h with cortisol showed, when compared to twin controls, more mature lung histology and pressure-volume relationships. 32P orthophosphate incorporation into whole lung phosphatidylcholine (PC) was increased in the four cortisol-treated lambs at 116--117 days but not at 121, 123, and 124 days gestation. 14C palmitate incorporation into PC or disaturated phosphatidylcholine (DSPC) was not enhanced at 116--117 days gestation. At 121 days in a cortisol-treated and at 128 days in a growth-retarded lamb fetus not treated with cortisol, a larger quantity of DSPC was present although the incorporation of 14C palmitate into DSPC per milligram DNA was the same. This indicated that the synthesis of DSPC had been initiated in the cortisol-treated and growth-retarded animals prior to the controls and at the time of sacrifice both were incorporating 14C palmitate at a similar rate suggesting similar rates of synthesis.

Fetal lamb lung phosphatidylcholine: Response to asphyxia and recovery

Acute fetal asphyxia resulting from maternal blood loss and hypotension causes a reduction in the incorporation of precursors into disaturated phosphatidylcholine, the principal lipid in the pulmonary surfactant. Treatment of the maternal hypotension is associated with return of fetal lung DSPC synthesis to control levels by 72 hours.

A physiologic model of the dehydroepiandrosterone to estrogen conversion system in the fetoplacental unit

A physiologic model of the dynamics of fetoplacental unit dehydroepiandrosterone (HDEA) to estrogen conversion is presented. A mathematical representation of this model is included. The model is used in Part II to determine the rate constant of DHEA to estrogen conversion and to successfully identify those fetuses in jeopardy from placental insufficiency within the population studied. This presentation permits critical comprehension of the model without extensive mathematical background.

The dehydroepiandrosterone loading test: III. A possible placental function test

The dehydroepiandrosterone loading test (DLT) has been used in a small population of normal and high-risk obstetric patients, to date, in an attempt to develop a dynamic test of placental function. In spite of its limited applications, it has shown reliability in discriminating, with statistical significance, between high-risk pregnancies that result in normally grown, undistressed infants, and high-risk pregnancies that result in infants showing signs of placental insufficiency. The present report expands the study population by presenting our data on 40 loading tests performed in 37 high-risk and normal obstetric patients. Results of 19 of these DLTs have been previously reported and are included herein for statistical analysis. The DLT utilizes an excess substrate load of dehydroepiandrosterone to assess the maximum capability of the placenta to convert it to estrogen. Although our previous report did not show false positive or negative results in the conversion rates, the present results (40 DLTs) found two (2 out of 17) false positives (12%) and two (2 out of 19) false negatives (11%). The highly significant correlation between DLT result and pregnancy outcome seen previously was preserved. In addition, the data of another five DLTs in four patients are presented. This group includes a pregnancy with a fetus with multiple congenital malformations, two patients with intrauterine fetal death, and a nonpregnant woman. The results are not included in the statistical analysis, but discussion of these results has interesting pathophysiologic implications.

Fetal lamb lung lavage and its effect on lung phosphatidylcholine.

Summary: The lungs of intrauterine 135–136-day-old lambs were lavaged with amnionic fluid, with or without meconium, to determine the effect on lung phosphatidylcholine (PC) concentration, synthesis, and function. No differences were apparent between animals lavaged with amnionic fluid or amnionic fluid with meconium. When lavaged lungs were compared to nonlavaged controls, no detectable differences were observed in histology or the quantity of saturated (SPC) and unsaturated phosphatidylcholine (UPC). However, the lavaged lungs retained a larger fraction of maximal lung volume at 5 cm H2O distending pressure and the incorporation of (32P) orthophosphate into lung PC was significantly reduced. In addition, two lavaged animals who became acidotic (pH < 7.20) exhibited decreased incorporation of (14C) palmitate into whole lung unsaturated, and saturated phosphatidylcholine.Speculation: These data indicate that amnionic fluid can reduce lamb lung de novo synthesis of PC and may contribute to the alterations in lung PC found in neonatal syndromes of respiratory distress. Acidosis may accentuate this effect.