Biomedical subjects

R K Creasy

Publications and source records attributed to R K Creasy.

At least 91 records · Page 5Linked to original sources

PubMed1977

Glucose and oxygen metabolism in normally oxygenated and spontaneously hypoxemic fetal lambs.

Whole blood glucose and oxygen concentration were measured in chronically catheterized fetal lambs, some of whom had implanted common umbilical artery flow transducers. Ten of the fetuses were well oxygenated (femoral arterial PaO2 less than 18 torr) and 13 fetuses had evidence of chronic hypoxemia (femoral arterial PaO2 less than 18 torr). The mean glucose uptake (54.0 +/- 7.6 S.E.M. mM. per kilogram per day), umbilical blood flow (230 +/- 13 S.E.M. ml. per kilogram per minute), and glucose/oxygen ratio (0.503) were the same in both fetal groups. The oxygenated fetuses had higher glucose levels at ang given maternal glucose concentration than the hypoxemic animals (p less than 0.001y and showed a correlation between glucose again across the placental circulation and the transplacental driving force for glucose (p less than 0.002). The hypoxemic fetuses, who had a higher per kilogram oxygen consumption than the oxygenated fetuses (p less than 0.05), showed no correlation between the amount of glucose taken up and the transplacental glucose concentration gradient.

Animals↗

PubMed1977

Uterine priming with oral prostaglandin E2 prior to elective induction with oxytocin.

Fifty pregnant women at term, with a cervix unfavorable for induction, were electively induced with intravenous oxytocin after priming with either oral prostaglandin E2 or a placebo. Oral PGE2 was effective in increasing the Bishop score and in inducing labor prior to the induction, but did not increase the incidence of successful inductions.

Administration, Oral↗

PubMed1977

Fetal umbilical venous-arterial differences of citrate in the chronically catheterised sheep.

Whole blood citrate concentration was measured simultaneously in the umbilical vein, fetal femoral artery and maternal artery in seven chronically catheterised pregnant ewes and their fetuses. The mean citrate concentration was 0-321 mmoles/litre in the umbilical vein, 0-297 mmoles/litre in the fetal femoral artery and 0-095 mmoles/litre in the maternal artery. The mean concentration difference for citrate across the fetal placental circulation was 0-024 mmoles/litre but this was not statistically significant (P less than 0-1).

Animals↗

PubMed1976

Effect of ritodrine on uterine activity, heart rate, and blood pressure in the pregnant sheep: combined use of alpha or beta blockade.

Ritodrine hydrochloride was administered parenterally to pregnant ewes during spontaneous or oxytocin-induced uterine activity. The effects of ritodrine on the uterus and cardiovasculature were assessed both with and without simultaneous administration of either alpha or beta blockade. Ritodrine was found to be an effective inhibitor of both spontaneous and induced uterine activity. Ritodrine did cause maternal tachycardia but no significant hypotension. Alpha-adrenergic blockade did not influence the effects of ritodrine. Beta blockade with propranolol reversed the uterine and cardiovascular effects of ritodrine, whereas beta blockade with practolol reversed the cardiovascular effects without interfering with the inhibition of uterine activity produced by ritodrine.

Adrenergic alpha-Antagonists↗

PubMed1976

Prenatal diagnosis of congenital anomalies in an intrauterine growth retarded fetus.

Chromosome analysis of amniotic fluid cells and amniotic fluid alpha-fetoprotein determinations were used to investigate a fetus with severe intrauterine growth retardation in the third trimester. The karyotype was 47,XY,18+ and increased alpha-fetoprotein levels indicated the presence of congenital malformations. We suggest that when severe fetal growth retardation is detected early in the antepartum course, amniotic fluid alpha-fetoprotein and amniotic fluid cell chromosome studies be done to determine if congenital anomalies may be an etiological factor.

Abnormalities, Multiple↗

PubMed1976

Hyperfibrinogenemia and polycythemia with intrauterine growth retardation in fetal lambs.

Plasma concentrations of albumin and fibrinogen and arterial hematocrits were determined during the last third of gestation in growth-retarded and control fetal lambs. The mean fetal plasma albumin concentration increased slightly as term approached and was not significantly different in the two groups. The mean plasma fibrinogen concentration did not change in the control fetuses, but was significantly elevated in the growth-retarded fetuses, as was the mean arterial hematocrit. The theoretical implications of these findings relative to capillary blood flow are discussed.

Animals↗

PubMed1976

Acetate as a metabolic substrate in the fetal lamb.

Fetal acetate metabolsim was studied in chronically catheterized fetal lambs of 110-141 days' gestation. Acetate concentration was measured enzymatically in whole blood drawn simultaneously from maternal and fetal pre- and postplacental vessels. The oxygen content of the fetal blood samples was also measured. Fetal umbilical venous acetate concentration was found to be proportional to the maternal arterial acetate concentration and had a mean value of 0.366 mM. Fetal blood acetate increased significantly, by a mean of 0.081 mM, during circulation through the placenta. This increase was proportional to both the maternal acetate concentration and the concentration gradient of acetate across the placenta. The mean maternal arterial acetate concentration was 1.153 mM. Maternal blood lost significant amounts of acetate, 0.112 mM, during circulation through the uterus and appeared to be the source of the acetate being gained by the fetus. It is estimated that a total of 23 mmol of acetate/kg of fetal weight is being taken up by the fetus each day, providing it with 0.560 g of carbon/kg. Comparisons of acetate uptake with fetal oxygen uptake indicate 10% of the daily fetal oxygen consumption would be required to completely oxidize the acetate being gained by the fetus.

Acetates↗

PubMed1976

Lactate and pyruvate as fetal metabolic substrates.

Lactate and pyruvate concentration differences across the fetal umbilical circulation and the maternal uterine circulation were measured in a chronic sheep preparation. Significant gains in lactate in both the fetal and maternal circulations were observed. The lactate taken up by the fetus would account for 32% of fetal oxygen consumption if oxidized. There was no significant change in pyruvate concentration across the fetal umbilical circulation; however, pyruvate was gained by maternal uterine blood.

Animals↗

PubMed1975

Effect of temperature on optical density of rabbit blood in dye dilution studies.

The optical desity of rabbit blood increased on cooling. This increase was additive to the deflection produced by indocyanine green at all concentrations measured. If calibration curves were not corrected for any increase in optical density produced by cooling the blood, and error (minimum 11%) was introduced in the estimation of cardiac output. The effect of temperature was investigated with three different densitometers. Its wave-length dependence did not follow the absorption spectrum of oxyhemoglobin.

Animals↗

PubMed1975

Appearance of paoproteins of pulmonary surfactant in human amniotic fluid.

We have isolated and partially characterized the protein found in surface-active material from adult human lungs, and have determined the time of appearance of this protein in amniotic fluid. Fluids were drawn at gestational ages from 12 to 44 wk, and were assayed for their concentration of apoprotein by an agglutination immunoassay. Surfactant apoprotein ((defined as that protein which is reproducibly found in purified preparations of surface active material) was usually first detected from 30 to 32 wk gestation, and its concentration increased almost fivefold to a maximum at 37 wk. The change in apoprotein concentration was approximately paralleled by the change in phospholipid concentration. At all gestational ages there was wide variability in both phospholipid and apoprotein concentrations, and the time of appearance of the apoprotein in amniotic fluid differed among fetuses. The results suggest that the presence of surfactant apoprotein in amniotic fluid is coincident with the biochemical and morphological maturation of the fetal lung, and are additional evidence that this apoprotein is cosecreted with the lipids of surface-active material.

Amniotic Fluid↗

PubMed1974