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Biomedical subjects

C Crenshaw

Publications and source records attributed to C Crenshaw.

At least 37 records · Page 2Linked to original sources
PubMed1979

Fetal lamb lung lavage and its effect on lung phosphatidylcholine.

UNLABELLED: 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 less than 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.

Amniotic Fluid↗
PubMed1977

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.

Acute Disease↗
PubMed1977

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.

Animals↗
PubMed1977

Studies on ovine placental lactogen secretion by homologous radioimmunoassay.

The concentrations of ovine placental lactogen (oPL) have been determined in maternal plasma, umbilical cord plasma, and allantoic fluid by an homologous radioimmunoassay for oPL which is sensitive to 0-1 ng hormone. Ovine placental lactogen was first detected in maternal plasma at 41-50 days of gestation and reached a peak concentration of 2547 +/- 226 (S.E.M.) ng/ml at 121-130 days in ewes with singleton gestations. The oPL concentration in cord plasma was 336-4 +/- 60-3 ng/ml and in allantoic fluid was 29-6 +/- 6-4 ng/ml. After surgical removal of the placenta, oPL disappeared from maternal plasma with a half-life of 29-1 +/- 1-3 min.

Allantois↗
PubMed1976

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

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.

Dehydroepiandrosterone↗
PubMed1976

A physiologic model of the dehydroepiandrosterone to estrogen conversion system in the fetoplacental unit. II. Preliminary clinical application--the dehydroepiandrosterone loading test.

A dehydroepiandrosterone (DHEA) loading test (DLT) is described. The results of 19 DHEA loading tests in as many third-trimester obstetric patients are presented. Analysis involves inspection of the raw data and the application of the physiologic model of the DHEA to estrogen conversion system described in the preceding paper (Part I). The DLT results show that within the population studied, the conversion rate of DHEA to estrogens is lower in patients with placental insufficiency than in normal patients (N = 5, p = 0.002) or in patients with various complications of pregnancy who deliver normally grown, undistressed infants (N = 6, p = 0.001). Routine clinical application must await more extensive evaluation to preclude the existence of forms of placental insufficiency not detected by this means, or normal states resulting in "false-positive" tests. These initial clinical results are intended primarily to demonstrate the potential clinical applicability of the physiologic model described in Part I.

Dehydroepiandrosterone↗
PubMed1975

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.

Animals↗
PubMed1975

Development of the sheep as an animal model to study placental lactogen physiology.

Ovine placental lactogen, purified from term sheep cotyledons, has been found to have chemical and biologic properties similar to those of human placental lactogen, ovine growth hormone, and ovine prolactin. OPL stimulates lactation in vivo and in vitro and binds to prolactin and growth hormone membrane receptors. Its binding to growth hormone receptors is approximately 20 times greater than that of hPL, suggesting that its somatotrophic potency is greater than that of hPL. Preliminary in vivo studies in the sheep indicate that oPL affects maternal carbohydrate, lipid, and protein metabolism and that its effects are, in part, similar to those of hPL and growth hormone.

Animals↗