Management of missed abortion and fetal death in utero

Termination of pregnancy in missed abortion and intra-uterine fetal death was accomplished using vaginal suppositories of 20 mg PGE₂ in 31 cases and the results were compared with oxytocin induction (with or without estrogen pre-treatment) in 17 cases at the doses routinely used in our hospital. The PG suppositories proved much more superior (96.7%) than oxytocin (47.7%), but induced a higher rate of side effects. The latter were not serious and were generally tolerated by the patients. There was a positive correlation between duration of fetal retention in utero and the induction expulsion time. The over all patient acceptance of the method was quite favourable and the approach appears to be a definite advance towards management of these cases.     

Purification of fetal rat hepatocytes

Fetal rat hepatocytes of greater than 90% purity from 16 and 20 day fetuses were prepared by combining the use of sedimentation at unit gravity and discontinuous Percoll gradients. With slight modification the method could also be used to purify 13 day fetal rat hepatocytes. At each day examined the method produced several subpopulations of hepatocytes. Hepatocytes were identified by morphology and the presence of alpha-fetoprotein. Fetal hepatocytes purified in this way were able to attach to a substratum, and retained the ability to synthesize alpha-fetoprotein in short-term culture.     

Almitrine inhibits breathing movements in fetal sheep in utero

Whilst hypoxia stimulates fetal peripheral chemoreceptors, fetal breathing movements do not increase as hypoxia also has central effects. We wondered whether specific stimulation of the arterial chemoreceptors by almitrine would produce a stimulation of fetal breathing movements. When almitrine was given to 5 intact and 3 peripherally-chemodenervated fetal sheep in utero, fetal breathing movements rapidly ceased for 1-12 h. There was also a decrease in the amount of time spent in low voltage electrocortical activity. The effects of almitrine are therefore similar to those of hypoxia, and are independent of the peripheral chemoreceptors. Thus it may be a valuable tool in the study of the control of fetal breathing.     

Serine and glycine transport in fetal ovine hepatocytes

The role of hepatic serine and glycine transport in the regulation of the biosynthesis of serine by the fetal liver has not been studied. The goal of this study was to characterize serine and glycine transport and utilization at physiologic concentrations in primary cultures of fetal ovine hepatocytes. Primary culture of hepatocytes from mid gestation ( approximately 90 days) and term ( approximately 135 days) fetal sheep were studied after overnight serum free culture. At both gestational ages, the initial rate for sodium dependent 300 microM serine transport (1697+/-131 pmoles/min/mg protein at mid, 1765+/-544 at term) was fourfold greater than sodium dependent 300 microM glycine transport (309+/-54 at mid, 579+/-252 at term). At physiologic concentrations (300 microM), 69+/-7% of serine and 49+/-8% of glycine transport was sodium dependent. At term, sodium dependent serine transport has a V(max) of 1751+/-348 pmoles/min/mg protein and a K(m) of 159+/-111 microM. Sodium independent serine transport has a V(max) of 904+/-185 and a K(m) of 416+/-188 microM. Sodium dependent glycine transport has a V(max) of 410+/-69 and a K(m) of 2290+/-895 microM while sodium independent glycine transport exhibits non-saturable kinetics. Glycine (300 microM) sodium dependent transport was not inhibited by methyl-AIB while sodium dependent 300 microM serine transport was inhibited (31%). n-Ethylmaleimide inhibited sodium dependent serine and glycine transport by 36+/-9% and 37+/-2% respectively in term hepatocytes. Cysteine inhibited sodium dependent serine transport by 37%. Sodium independent glycine transport at 300 microM was higher in low glucose (1.1 mM) medium (881+/-76 pmoles/min/mg protein) compared to high glucose (5.5 mM) medium (510+/-60 P=0.004). There were no significant differences in serine or glycine incorporation into RNA, DNA, glycogen or lipid and protein. The predominance of serine transport over glycine at physiologic concentrations suggests that inward cellular amino acid transport of serine and glycine is not likely to be a regulatory mechanism that would favor serine biosynthesis in fetal ovine hepatocytes.     

Thymic regulation of primate fetal ovarian-adrenal differentiation

We report that fetal thymectomy inhibits oogenesis and induces abnormal ovarian differentiation in rhesus monkeys. In utero thymectomy (n = 5) elevated plasma follicle-stimulating hormone (7.8 +/- 1.1 microgram/ml vs. 4.2 +/- 0.5 microgram/ml; P less than 0.05) and decreased plasma prolactin (24.5 +/- 3.3 ng/ml vs. 76.3 +/- 11.2 ng/ml; P less than 0.05) concentrations compared with intact controls (n = 12), but did not change plasma luteinizing hormone, estradiol, cortisol, dehydroepiandrosterone sulfate, or thymosin-alpha 1 concentrations. In utero thymectomy reduced the weight of neonatal ovaries and adrenal glands, but not hepatic, renal, splenic, or total body weights. After fetal thymectomy, newborn ovaries (n = 8) contained a reduced total number of germ cells (123,926 +/- 11,651 vs. 432,034 +/- 40,311; P less than 0.001). The percentages of individual germ cell types were similar between thymectomized and intact groups (n = 11) except for an increased percentage of preantral-antral follicles in the thymectomy group (P less than 0.01). Our results indicate that the primate fetal thymus regulates antenatal ovarian follicular development, perhaps by interactions between the nascent immunologic and pituitary-ovarian systems.     

Temperature responses following ventilation of the fetal sheep in utero

The mammalian fetus produces significant quantities of heat. This passes to the mother principally through the placenta and to a lesser extent via a pathway comprising the skin, amniotic fluid, and uterine wall. To assess the importance of the lesser pathway, temperature responses were recorded in 7 near-term fetal sheep after intrauterine ventilation with oxygen, after snaring the umbilical cord to block the placental route, and following fetal death. Four distinguishing characteristics of responses were observed: fetal temperature rose 0.10 +/- 0.03 (SEM) degrees C after oxygenation; it rose progressively an additional 0.9 +/- 0.1 degrees C during the 90-min interval after cord snaring; amniotic fluid temperature rose slowly until it was about midway between fetal and maternal temperature; and after fetal death, fetal amniotic fluid temperatures fell slowly. In a simple mathematical model with constant parameters these results could not be explained fully. It was necessary to assume that heat production rose with increased oxygenation and elevated body temperature and that ventilation increased heat transfer through the amniotic fluid, as would occur if chest wall movement were stirring the fluid. Using the model, the value for heat conductance from fetal skin to amniotic fluid was estimated to be 10.5 watts degrees C-1 under basal conditions.     

Initiation of pulmonary gas exchange by fetal sheep in utero

The role of umbilical cord occlusion in the initiation of breathing at birth was investigated using unanesthetized fetal sheep that were provided with access to a tracheal supply of hyperoxic air. Near-term fetuses were studied in utero to eliminate extraneous sensory stimuli. Gasping movements began 1.4 +/- 0.1 min after cord occlusion. Breathing was irregular for several minutes before continuous breathing (greater than or equal to 40 min-1) began 6 +/- 1 min after cord occlusion (n = 10). Arterial PO2 rose significantly from 18 +/- 2 mmHg before occlusion and was 115 +/- 15 mmHg immediately before cord release at 15 or 30 min. Breathing continued even during high-voltage electrocortical activity. Cord release caused the breathing rate to decrease from 77 +/- 13 min-1 during the last 5 min of cord occlusion to 5 +/- 3 min-1 10 min after cord release (P less than 0.002; n = 7). Results indicate the change from placental to lung gas exchange can occur in the absence of sensory and thermal changes normally present at birth and that the transition is reversible.     

Metabolic and hormonal responses to cooling the fetal sheep in utero

The metabolic and hormonal effects of cooling 10 fetal sheep in utero (115-142 days of gestation) for 2h were studied. The fetal core temperature fell by 2.81 +/- 0.14 degrees C while the maternal temperature fell 0.86 +/- 0.15 degrees C. This hypothermia caused a significant rise in the fetal and maternal plasma glucose concentrations (P less than 0.001) and a fall in the fetal insulin concentrations (P less than 0.01). The fetal plasma lactate and cortisol concentrations rose rapidly (P less than 0.01) while the growth hormone fell (P less than 0.01) and remained low until cooling ceased when a rapid rebound occurred. There was no significant change in any of the fetal iodothyronines and no elevation of nonesterified free fatty acid concentrations, in contrast to the rapid rise (P less than 0.01) which occurred when newborn lambs were cooled. These observations demonstrate that appropriate glucose, insulin, lactate and cortisol responses to hypothermia have differentiated by 120 days of gestation. However, neither a thyroid hormone response nor an elevation in free fatty acid levels was observed. Thus not all components of the thermogenic response to hypothermia can be demonstrated in the late gestation fetail sheep in utero.     

Haemodynamic and catecholamine responses to hypothermia in the fetal sheep in utero

Chronically catheterised fetal sheep (117-134 days) were cooled in utero via a tubing coil placed around the fetal trunk through which cold water was circulated for one hour. The fetal core temperature was reduced by 5.51 +/- 0.61 degrees C. This hypothermia was associated with tachycardia (P less than 0.001) and hypertension (P less than 0.001) (n = 12). The tachycardia was abolished by treatment with propranolol (n = 4) and the hypertension by treatment with phentolamine (n = 5). Blood flow in the left umbilical artery was measured by an electromagnetic flow probe in 4 fetuses and rose (P less than 0.001) with fetal cooling. The increase in blood flow was abolished by treatment with either phentolamine or propranolol. These observations are consistent with a redistribution of fetal blood flow from peripheral tissues to placental and thermogenic tissues during cooling. Fetal plasma adrenaline and noradrenaline concentrations rose (P less than 0.01) during fetal cooling (n = 5). These studies demonstrate that catecholamine and cardiovascular responses to environmental hypothermia have differentiated prior to birth in the sheep fetus.     

Measurement of umbilical blood flow in fetal lambs in utero.

We continuously measured umbilical blood flow in fetal lambs in utero by placing an electromagnetic flow transducer around the common umbilical artery. Umbilical arteries originate from a short common segment as the terminal branches of the descending aorta. This segment was isolated by a retroperitoneal surgical approach and encircled with a specially constructed electromagnetic flow transducer. Catheters were also placed in fetal vessles to monitor pressure and derive flow values by the radionuclide-labeled microsphere technique. The fetus and ewe were allowed to recover for two days before studies were performed. Average umbilical blood flow obtained in 11 animals with the transducer was 199 ml/kg per min. In seven animals flow measurements obtained with the transducer were compared with those derived from microsphere injections. Paired measurements varied by an average of only 5.3%. This technique makes possible the accurate and instantaneous measurement of umbilical blood flow in fetal lambs in utero over a prolonged period.     

Pulmonary pressure-flow relationships in the fetal lamb during in utero ventilation

Pressure-flow relationships in the ventilated lung have not been previously determined in undelivered fetal sheep. Therefore we studied 11 late-gestation chronically prepared fetal sheep during positive-pressure ventilation with different gas mixtures to determine the roles of mechanical distension and blood gas tensions on pressure-flow relationships in the lung. Ventilation with 3% O2-7% CO2 produced a substantial fall in pulmonary vascular resistance even though arterial blood gases were not changed. Increases in pulmonary arterial PO2 during ventilation were associated with falls in pulmonary vascular resistance beyond that measured during mechanical distension. Decreases in pulmonary arterial PCO2 and associated increases in pH were also associated with falls in pulmonary vascular resistance. Pulmonary blood flow ceased at a pulmonary arterial pressure that exceeded left atrial pressure, indicating that left atrial pressure does not represent the true downstream component of driving pressure through the pulmonary vascular bed. The slope of the driving pressure-flow relationship in the normal mature fetal lamb was therefore different from the ratio of pulmonary arterial pressure to pulmonary arterial flow. We conclude that mechanical ventilation, increased PO2 and decreased PCO2, and/or increased pH has an important influence on the fall in pulmonary vascular resistance elicited by positive pressure in utero ventilation of the fetal lamb and that the downstream driving pressure for pulmonary blood flow exceeds left atrial pressure.     

Analysis of metopirone-induced hypertrophy of adrenals in fetal rats encephalectomized in utero

Pregnant rats were treated with 30 mg metopirone (M) each day for 2 days and autopsied on the third day in various gestational periods (Days 18-20, 19-21, and 20-22). Control rats were treated with saline alone (S). The adrenals of intact fetuses in M-treated dams were significantly heavier than those of intact fetuses in S-treated dams in every experimental period. In both M- and S-treated dams, the adrenals of encephalectomized (E) fetuses were lighter than those of intact littermates. However, in the experimental period of Days 18-20 and 19-21, the adrenals of E fetuses in M-treated dams were slightly but significantly heavier than those of similar E fetuses in S-treated dams. In contrast, in the experimental period Days 20-22, there was no significant difference in the weight of adrenals of E fetuses of M- and S-treated dams. These changes in fetal adrenal weight were reflected histologically in parallel changes in the size of adrenocortical cells. The observations suggest that the fetal adrenal hypertrophy following maternal treatment with metopirone can occur to some extent independent of the fetal brain, but that close to the end of gestation the hypertrophy occurs completely under the control of the fetal brain.     

In utero transplantation of fetal liver stem cells in humans.

Following 15 years experience in postnatal fetal liver transplantation (FLT), we have developed a new therapeutical method, namely the in utero transplantation of stem cells from the human fetal liver. This early transplant takes advantage of the immunological tolerance that exists in young fetal recipients. The three fetuses that we treated were 28, 26, and 12 weeks of age (weeks after fecundation). The first two patients had immunodeficiencies, the third one had thalassemia major. Donor cells were obtained from 7- to 10-week-old fetuses, with conditions approved by the National Committee for Bioethics. Donors and recipients were not matched. The fetal cells were infused through the umbilical vein of the first two patients and injected intraperitoneally into the third one, under ultrasonic visualization. The first patient, born in 1988, has evidence of engraftment and reconstitution of cell-mediated immunity: initially 10% than 26% of lymphocytes of donor origin (with distinct phenotype), T cell responses to tetanus toxoid and candida antigens. This child, who had bare lymphocyte syndrome, has no clinical manifestation of the disease and lives normally at home. The second child was born in 1989 and it is too early for a thorough evaluation of the immunological effects of the transplant, although donor cell engraftment has been proven (Y chromosome in this female patient). The third patient has also evidence of donor cell take (Y chromosome in a female patient) but the effect on thalassemia has not yet been fully analyzed (donor hemoglobin present in small quantity). In all three cases, no side effect of any kind developed in the mother nor in the fetus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Platelet-activating factor induces glycogen degradation in fetal rabbit lung in utero

The role of platelet-activating factor (PAF, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in initiating glycogen breakdown in the fetal rabbit lung was assessed by intraperitoneal administration of this potent ether-linked glycerophospholipid. Forty-five min after in utero injection of PAF (2.5 X 10(-7) mol), fetal pulmonary and hepatic glycogen concentrations were reduced from 326 to 256 and from 9.8 to 6.6 micrograms of glycogen/mg protein, respectively. Glycolytic activity was similarly increased as judged by an elevation of lactate (2-fold) in lung, liver, and plasma upon PAF injection. These actions of PAF were dose- and time-dependent. The glycogenolytic response did not occur when an equimolar dose of the inactive enantiomer, D-PAF was injected. Pretreatment of the fetus with a specific PAF receptor antagonist, SRI-63-441, prevented the PAF response. We have previously demonstrated (Hoffman, D. R., Truong, C. T., and Johnston, J. M. (1986) Biochim. Biophys. Acta 879, 88-96) that PAF biosynthesis and PAF concentrations increase significantly on day 24 of fetal rabbit lung development. A concurrent decrease in pulmonary glycogen concentration at this point of gestation is potentially reflective of the PAF-induced action. Thus, these observations would suggest a role for PAF in the normal physiology of fetal lung maturation.