Barriers to enrollment in a randomized controlled trial of hydrocortisone for cardiovascular insufficiency in term and late preterm newborn infants.

OBJECTIVE: To analyze reasons for low enrollment in a randomized controlled trial (RCT) of the effect of hydrocortisone for cardiovascular insufficiency on survival without neurodevelopmental impairment (NDI) in term/late preterm newborns. STUDY DESIGN: The original study was a multicenter RCT. Eligibility: ⩾34 weeks' gestation, <72 h old, mechanically ventilated, receiving inotrope. Primary outcome was NDI at 2 years; infants with diagnoses at high risk for NDI were excluded. This paper presents an analysis of reasons for low patient enrollment. RESULTS: Two hundred and fifty-seven of the 932 otherwise eligible infants received inotropes; however, 207 (81%) had exclusionary diagnoses. Only 12 infants were randomized over 10 months; therefore, the study was terminated. Contributing factors included few eligible infants after exclusions, open-label steroid therapy and a narrow enrollment window. CONCLUSION: Despite an observational study to estimate the population, very few infants were enrolled. Successful RCTs of emergent therapy may require fewer exclusions, a short-term primary outcome, waiver of consent and/or other alternatives.

Effect of maternal diabetes on the expression of genes regulating fetal brain glucose uptake.

Diabetes alters adult brain glucose uptake and glucose transporter 1 gene expression. To investigate the effect of diabetes on genes regulating fetal brain glucose uptake, we examined the effect of moderate (blood glucose 10-16.7 mM, normoinsulinemia) and severe (blood glucose > 16.8 mM, hypoinsulinemia) maternal diabetes on the expression of genes regulating fetal brain glucose uptake in the genetically nonobese diabetic mouse. In the moderately diabetic state, a 50% decline in fetal brain GLUT1 mRNA levels was associated with a 20% increase in the corresponding GLUT1 protein levels. Simultaneously, although fetal brain GLUT3 mRNA and protein levels were barely detectable, no change in hexokinase I enzyme mRNA, protein (115,000 and 100,000 M(r)) or activity, was noted. In the severe form of maternal diabetes GLUT1 protein was unchanged, GLUT3 protein levels remained low, and a 2- to 3-fold increase in the lower molecular form of the hexokinase I protein (100,000 M(r)) and enzyme activity occurred. These observations suggest that moderate and severe forms of maternal diabetes do not affect the fetal brain glucose transporter levels to a physiologically significant extent. The severe form of maternal diabetes, however, enhances 1.5- to 3-fold the expression and activity of hexokinase I. This enzyme mediates the rate-limiting step in brain glucose metabolism, namely the intracellular conversion of glucose to glucose-6-phosphate.

Development of responsiveness of dispersed rabbit adrenocortical cells to synthetic adrenocorticotropic hormone [ACTH-(1-24)] and alpha melanocyte-stimulating hormone.

Although there is a considerable body of evidence suggesting increased activity of the fetal and neonatal adrenal in the rabbit, the mechanism responsible for this increased activity has not yet been determined. This report provides data on the function of dispersed fetal, neonatal, and adult rabbit adrenocortical cells in vitro. During the period between 22-29 days gestation, the fetal rabbit adrenal cortex increases its cell number and three features of in vitro activity: basal corticoid production, responsiveness to synthetic ACTH-(1-24), and maximum corticoid secretory capacity. None of these variables is significantly altered during the first 3-5 days of neonatal life or in adult rabbits. At no time was any corticoid response observed to alpha MSH.

Vesico-umbilical fistula: a complication of umbilical artery cutdown.

A vesico-umbilical fistula occurred following cut down for catheterization of the umbilical artery in a premature infant; a previously unreported complication. Knowledge of the variations in anatomical structure of the urachus and umbilical arteries at birth will help to prevent this complication.

Revisiting early hypothyroidism screening in infants with Down syndrome.

OBJECTIVE: To identify if the incidence of hypothyroidism in infants with Down syndrome is higher than previous childhood estimates (15%) when examined prior to the standard retesting at 6 months of age. STUDY DESIGN: A retrospective observational cohort study of 122 children with Down syndrome admitted to a university-based birthing hospital between May 2000 and March 2012. Demographic data (for example, date of birth, gender, gestational age, inborn) and diagnostic data (Down syndrome, congenital heart disease and gastrointestinal disease) were cross-linked with thyroid hormone laboratory tests (total thyroxine, free thyroxine and thyroid stimulating hormone) to determine incidence of identified hypothyroidism and thyroid testing prior to 4 months of age (n=80). RESULT: In all, 32.5% were found to have any hypothyroidism. Of these, 14 were primary hypothyroidism (17.5%) needing supplemental T4 therapy, 12 were compensated hypothyroidism (15%) and euthyroid was identified in 54 infants (67.5%). CONCLUSION: Despite normal newborn screens, the incidence of any hypothyroidism (early compensated hypothyroidism and primary hypothyroidism) was higher than previously reported.

Glucocorticoids increase pulmonary epidermal growth factor receptors in female and male fetal rabbit.

Experimental evidence in animals and humans suggest that glucocorticoids enhance fetal pulmonary maturation. Mechanisms of glucocorticoid effects remain unclear; but apparently include up regulation of fetal pulmonary insulin and beta-adrenergic receptors. A role of Epidermal Growth Factor (EGF) in fetal lung maturation through plasma membrane bound receptors has been recently proposed. Betamethasone, 0.085 mg/kg, was administered on 25th and 26th day of gestation to the rabbit doe. Fetal pulmonary EGF receptor characteristics in male or female fetuses were studied on the 27th day of pregnancy. The percent specific binding of 125-I-EGF to lung plasma membranes (LPM) and the number of receptor sites per mg of LPM protein or DNA content were significantly higher in the glucocorticoid treated female as well as male fetuses when compared to the control pups, with no difference in the Kd. Presence of high affinity receptors for EGF and their up regulation by glucocorticoids support the hypothesis that EGF plays an important role in fetal lung maturation and that some of the beneficial effects of glucocorticoids in decreasing the incidence of HMD may be mediated through its interaction with EGF.

Inulin space studies in fetal sheep.

Extracellular volume was estimated in fetal sheep by measuring the 14C inulin space in 6 in situ unanesthetized fetal lambs at gestational ages ranging from 120 to 145 days (term = 150 days). The total inulin space ranged from 979 to 1,510 ml. A positive correlation between total inulin space and gestational age (r = 0.65) was noted, such that fetal lambs of 120 days gestation had a predicted inulin space of 1,072 ml and fetal lambs near term at 145 days gestation had an inulin space of 1,422 ml. However, since fetal weight increases with gestation, inulin space expressed as a percent of body weight actually decreased with gestational age (r = -0.80), so that at 120 days gestation the fetus would have an estimated inulin space of 59% of body weight and at 145 days the fetus would have an inulin space of only 34% of body weight.

A differential effect of thyroxine and glucocorticoids on fetal brain and heart insulin receptor.

We investigated the effect of thyroxine (T4), glucocorticoids, and T4 + glucocorticoids on the maturation of fetal rabbit brain and heart insulin receptors. Five doses of T4 over 10 days (50 micrograms/kg body weight per dose) were administered to the mother; significant amounts crossed the placenta (fetal serum free T4 = 0.75 +/- 0.08 versus a control of 0.21 +/- 0.02 ng/dl, p less than 0.02) and increased the specific binding of [125I]insulin to 30-day-old fetal heart membranes from a control of 3.6 +/- 0.74% per 100 micrograms protein to 5.8 +/- 0.19% (p less than 0.05). Curvilinear Scatchard plots revealed an increase in receptor number X 10(7) micrograms protein-1 from 137 +/- 4 to 244 +/- 39 (p less than 0.05) with no change in receptor affinity. No appreciable alteration by T4 in the [125I]insulin-specific binding and receptor number of 30-day fetal brains was noted. Fetal heart glycogen content was decreased and there was a small increase in plasma glucose concentration in the T4-treated group (each p less than 0.02). Betamethasone at 0.17 mg/kg did not affect the specific binding of [125I]insulin to 27-day fetal heart or brain plasma membranes, although a decrease in heart glycogen content and an increase in plasma glucose concentration were observed (each p less than 0.02). Also T4 + betamethasone did not alter the [125I]insulin binding to 27-day fetal heart or brain plasma membranes, but resulted in an additive effect (a marked depletion) on cardiac glycogen (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogeny of rat lung type IV collagenase mRNA expression and collagenolytic activity during the perinatal period.

The extracellular matrix is important in the cellular differentiation and morphogenesis of the lung. The basement membrane (BM), an integral part of the extracellular matrix, is composed primarily of type of IV collagen. The metabolism of type IV collagenase is important in remodeling of BM that occurs during growth. We examined the ontogeny of rat lung type IV collagenase mRNA expression, type IV collagenolytic activity and type IV collagen content during the perinatal period. In addition, the effect of prenatal glucocorticoid (GC) treatment on fetal lung type IV collagenase mRNA expression and type IV collagenolytic activity was studied. Lung polyadenylated RNA was extracted and subjected to Northern blot analysis and laser densitometry after hybridization with human type IV collagenase (approximately 72 kD) and rat actin cDNA probe. Type IV collagenolytic activity and type IV collagen concentration were quantitated by an enzymatic and a radioimmunoassay, respectively. While lung type IV collagenase mRNA to alpha-actin ratio and type IV collagenolytic activity were highest prior to birth (21-day fetus), the lung type IV collagen concentration was lowest at this time. Prenatal GC treatment did not influence type IV collagenase mRNA expression or the collagenolytic activity. A role for fetal lung type IV collagenase in preparation for the neonatal pulmonary vascular and/or alveolar adaptation is proposed.

Varying brain insulin concentrations differentially regulate the fetal brain insulin receptor.

We investigated the downregulating effect of varying states (physiologic and pharmacologic) of systemic and intracranial hyperinsulinism on the 28 to 30 day fetal rabbit brain insulin receptor. Alloxan-induced maternal diabetes (n = 5) produced mild fetal hyperinsulinemia (D) (plasma insulin concentrations = 59.80 +/- 8.10 microU/ml, control = 26.25 +/- 3.70; p less than 0.01), whereas systemic administration (IMI) of 1.0 U (n = 4) and 2.0 U (n = 4) of insulin to the fetus resulted in moderate (103.13 +/- 34.63 microU/ml) and severe (288.3 +/- 51 microU/ml) fetal hyperinsulinemia respectively. All three states of systemic hyperinsulinemia neither altered the fetal brain insulin content nor the brain insulin receptor number and affinity. 0.01 U (n = 4) of intracranial insulin administration (ICI) increased the brain insulin content four-fold (p less than 0.01) but did not alter the brain insulin receptor number or affinity. 0.1 (n = 5) and 2.0 U (n = 7) of intracranial insulin increased the brain insulin content to supraphysiologic concentrations (p less than 0.01) and decreased the fetal brain insulin receptor number (p less than 0.01), the affinity remaining constant. We conclude that 1) regardless of the ability of insulin to cross the blood brain barrier, the downregulation of the brain insulin receptor is insulin dose-dependent and 2) the downregulation of the fetal brain insulin receptor is not a physiologic but a pharmacologic effect of insulin.

Acute bronchospasm resembling status asthmaticus during the neonatal period.

Recently, we encountered four neonates who developed severe reversible partial lower airway obstruction. This communication describes their clinical course and the pathogenesis and treatment of acute bronchospasm resembling status asthmaticus and leading to life-threatening respiratory acidosis.

Effect of simultaneous administration of betamethasone and triiodothyronine (T3) on the development of functional pulmonary maturation in fetal rabbit.

Recent experimental evidence suggests that a combination of glucocorticoid and thyroid hormone may be more effective than either hormone alone in accelerating morphologic as well as biochemical mammalian fetal lung maturation. We have demonstrated that IM administration of T3 to the rabbit doe is associated with enhanced functional fetal lung maturation. We investigated the effect of simultaneous administration of T3 and betamethasone on the development of functional fetal lung maturation and the duration of survival after premature delivery. On day 25 and 26 of pregnancy, T3 (175 micrograms/kg/dose) betamethasone (85 micrograms/kg/dose), T3 plus betamethasone or the appropriate amount of the vehicles were injected. The functional fetal pulmonary maturity and the duration of survival after premature delivery were assessed on day 27 of gestation. Although enhanced functional fetal lung maturation was observed after T3 or betamethasone administration, there was no additive effect after simultaneous administration of both. The duration of survival on premature delivery was enhanced in betamethasone but not T3 or T3 plus betamethasone group when compared to control. Further animal experimentation seems necessary before a clinical trial of T3 plus betamethasone therapy is considered.

The fetal heart insulin receptor responds differently to varying plasma insulin concentrations.

We investigated in vivo the effect of varying plasma concentrations of insulin on the 28- and 30-day-old fetal rabbit heart insulin receptors using plasma membranes. Alloxan induced maternal diabetes (n = 5) associated with fetal hyperglycemia and mild hyperinsulinemia (59.80 +/- 8.10 microU/ml versus a control of 26.25 +/- 3.70, p less than 0.01) increased the insulin receptor number from a control (30 d) of 168 +/- 1.01 to 320 +/- 34 X 10(10)/mg protein (p less than 0.01). Fetal administration of 1.0 U of insulin (n = 4) resulting in normoglycemia and moderately high plasma insulin concentrations (103.3 +/- 34.63 microU/ml versus a control of 13.72 +/- 1.60, p less than 0.05) did not alter the insulin receptor number (28 d). On the other hand fetal administration of 2.0 U of insulin (n = 4) resulting in hypoglycemia and severely high plasma insulin concentrations (288.3 +/- 51 microU/ml versus a control of 13.72 +/- 1.60, p less than 0.01) decreased the insulin receptor number from a control (28 d) of 200 +/- 23 to 82 +/- 23 X 10(10)/mg protein (p less than 0.01). The receptor affinity remained constant. We conclude that the downregulation (decrease) of the fetal heart insulin receptors in vivo is not a physiologic but a pharmacologic effect of insulin.

Effect of maternal administration of thyrotropin-releasing hormone or DN1417 on functional and morphologic fetal rabbit lung maturation and duration of survival after premature delivery.

Though maternal treatment with thyrotropin-releasing hormone (TRH) for prevention of hyaline membrane disease has been utilized, precise mechanisms of TRH in accelerating fetal lung maturation remain unclear. We studied the effect of maternally administered TRH or DN1417 (an analog of TRH) on functional and morphologic fetal rabbit lung maturation and the duration of survival after premature delivery. Because DN1417 retains the neurotransmitter but not the neuroendocrine effects of TRH, this study enables us to determine which of these effects was responsible for enhancement of lung maturation. TRH or DN1417 (0.2 mg/kg/dose) or saline was injected intravenously into New Zealand White rabbit does 48, 36, 24, 12 and 2 h prior to sacrifice on day 27 of gestation. Functional pulmonary maturity was assessed by pressure-volume hysteresis, and morphologic maturity was assessed by histologic technique. Maternal administration of TRH or DN1417 enhanced both functional and morphologic fetal lung maturation as well as the duration of neonatal survival after premature delivery. We propose that the effect of TRH in fetal lung maturation is due to neurotransmitter rather than neuroendocrine effects.

GLUT 1-glucose transporter protein in adult and fetal mouse lung.

We observed approximately 45-50 kD GLUT 1 protein in mouse lung homogenates and demonstrated a greater abundance in fetus compared to adult. In situ immunohistochemical analysis demonstrated GLUT 1 expression only in the perineural sheath of nerves. While the trapped fetal red blood cells expressed GLUT 1 abundantly, adult red blood cells were devoid of GLUT 1. No GLUT 1 was evident in fetal and adult lung alveolar and bronchiolar epithelial cells, vascular endothelial cells and the lung mesenchymal elements. Thus, GLUT 1 is not the major lung glucose transporter.

Cardiogenic shock associated with perinatal asphyxia in preterm infants.

Fetal and neonatal biophysical and biochemical changes were studied in four preterm infants who developed cardiogenic shock as a result of severe perinatal asphyxia. Fetal distress was documented by the presence of severe late and variable decelerations associated with decreased fetal heart rate variability. Severity of fetal acidosis was decumented by scalp and umbilical cord blood pH. Apgar scores at 1, 5, and 10 minutes were all equal to or less than 5. Although the clinical findings shortly after birth resembled respiratory distress syndrome, it was possible to make a primary diagnosis of cardiac failure with the recognition of cardiomegaly, hepatomegaly, electrocardiographic changes of myocardial hypoxia, decreased myocardial contractility, elevated central venous pressure, and severe lactic acidosis. The treatment of heart failure, including use of inotropic agents, resulted in rapid improvement in the clinical condition, with reversal of the abnormal findings within 24 to 36 hours. Concomitant with this improvement, the increase in arterial blood pressure was paralleled by increase in peripheral (toe) temperature.

Altered thyroidal states modulate the insulin receptor characteristics of the developing rabbit brain.

We investigated the effect of propylthiouracil (PTU)-induced hypothyroidism and T4-induced hyperthyroidism on the fetal and neonatal rabbit brain insulin receptors (number and affinity) using plasma membranes. PTU administration to the pregnant mothers resulted in low serum-free T4 and normal total T3 concentrations, while T4 therapy to the mothers resulted in high serum-free T4 and high total T3 concentrations in the fetus and neonate. PTU-induced hypothyroidism did not affect the fetal brain insulin receptors, cholesterol content (brain homogenate) or protein content. On the other hand, brain insulin receptor number and total brain cholesterol content decreased in the neonate. T4 therapy at 100 micrograms/kg reversed the serum T4 to the control value and normalized the neonatal brain insulin receptor number and cholesterol content while a higher dose of T4 (200 micrograms/kg) increased the neonatal brain insulin receptor number, cholesterol and protein content. We conclude that altered thyroidal states modulate the brain insulin receptor (number and affinity) in neonatal, but not fetal brain plasma membranes.

Ontogenesis of the insulin receptor in the rabbit brain.

We delineated the ontogeny of the brain insulin binding, insulin receptor number and affinity using plasma membranes isolated from the rabbit. Specific 125I-insulin binding and receptor number expressed per milligram of protein increased from the 20 day gestation fetus to the 1-day-old newborn, declining thereafter to attain adult values by day 6 of postnatal life. Specific 125I-insulin binding and the receptor number in the adult brain was less than the fetal and neonatal (1 day) brain receptors. Although a similar trend was observed specifically during fetal development, the changes in receptor number expressed per microgram DNA were not significant in the neonatal period. The adult brain insulin receptor number was higher than the 20- to 27-day fetus and similar to that of the 30-day fetus and the 1- to 5-day newborns. The total receptor number correlated linearly with the brain plasma membrane protein increment velocity. The affinity of the receptors increased during early fetal development (20-27 days) and remained constant thereafter in the postnatal period. We conclude that the ontogenic changes of the brain insulin receptors are similar to the ontogenic changes of brain plasma membrane protein. The developmental changes are more pronounced when the receptor number is expressed per milligram protein versus microgram DNA.

Delayed ultrastructural lung maturation in the fetal and newborn hypothyroid (Hyt/Hyt) mouse.

Thyroid hormones influence fetal and neonatal lung growth and maturation. However, the effect of naturally occurring, genetically determined hypo- or hyperthyroidism on fetal or neonatal lung maturation has not been examined. In the hyt/hyt mouse, primary hypothyroidism, which is characterized by a high serum TSH concentration, is transmitted as an autosomal recessive trait. It occurs due to a mutational defect in the beta-subunit of the TSH receptor. We studied the lung ultrastructure of the fetal [18-d-gestation (term = approximately 19.5 d)] and neonatal (< 1-d-old) hyt/hyt mouse. In addition, disaturated phosphatidylcholine and total phospholipid contents of newborn hyt/hyt mouse lungs were determined. Male and female hyt/hyt mice with a high serum TSH concentration were made euthyroid by adding 3,5,3'-triiodothyronine to drinking water and then mated. Balb-c mice served as euthyroid controls. Fetal and neonatal hyt/hyt mice had a higher serum TSH concentration than the Balb-c controls. Fetal hyt/hyt mouse lungs showed a large amount of intracellular glycogen and fewer lamellar bodies in epithelial type II cells compared with Balb-c fetal mouse lungs. The neonatal hyt/hyt mouse also showed signs of lung immaturity such as persistent epithelial cell glycogen, few lamellar bodies, reduced disaturated phosphatidylcholine content, and absent tubular myelin. We conclude that fetal and neonatal lung maturation is delayed in the hyt/hyt mouse with primary hypothyroidism.

Hyperoxia induces interstitial (type I) and increases type IV collagenase mRNA expression and increases type I and IV collagenolytic activity in newborn rat lung.

Oxygen toxicity is attributed to the reaction of oxygen metabolites with cellular components leading to cell destruction. Activation of latent human neutrophil interstitial collagenase by reactive oxygen species has been demonstrated. The potential role of collagenases in hyperoxic lung injury has not been investigated. We studied the effect of hyperoxia on newborn rat lung water content, morphology and ultrastructure, interstitial (type I) and type IV collagenase gene expression and type I and IV collagenolytic activity. We observed that hyperoxia causes pulmonary edema, alters newborn rat lung morphology in a sequential manner and produces ultrastructural alterations, induces type I and increases type IV collagenase mRNA expression, and increases type I and IV collagenolytic activity. A role for type I and IV collagenase in hyperoxic newborn lung injury or in the recovery following the injury is proposed.