Hours Of Extrauterine Life Research Articles

Human newborn hypergastrinemia: an investigation of prenatal and perinatal factors and their effects on gastrin.

Summary: Because gastrin is a potent gastric acid stimulus and gastric acid secretion begins soon after birth, we measured umbilical cord serum gastrins. We also examined multiple factors present during the gestation, labor, delivery, and immediate postpartum period to see what effect, if any, these might have on the serum gastrins. Two groups were studied: 217 newborn infants and 802 adults without Zollinger-Ellison syndrome. The newborns' median serum gastrin was 100 pg/ml compared to the adult median of 39 pg/ml. The newborn mean was 135 pg/ml and the corresponding adult value was 40 pg/ml (P < 0.001). Twenty-nine newborns had gastrin determinations greater than 200 pg/ml; five were greater than 500 pg/ml. All adult values were less than 200 pg/ml. Thirty-five neonatal and maternal factors were analyzed to determine their effect on the gastrin levels found. No factor was found to have a significant effect except that Negro infants and maternal sickle cell trait were found to be associated with increased values. Nineteen maternal medications were also evaluated. None, including oxytocin and atropine, were found to have any effect. Serum gastrin levels continued to be elevated at hour 4 (x = 80 pg/ml) and hour 8 (x = 72 pg/ml) of life. The newborns secreted small amounts of gastric acid in response to this stimulus (range = 0.010 to 0.022 mEq/kg/hr). Speculation: During the transition to extrauterine life, the fetus is exposed to many varied stimuli. Increased vagal activity and catecholamine secretion are two physiologic reactions which occur in response to these stimuli. Both of these are known to stimulate gastrin release from G cells during extrauterine life and may account for the increased levels found at the time of delivery. The elevated gastrin levels found after birth may also be in response to these factors; however, decreased metabolism may play a role too. It is known that the kidney is the major site for gastrin metabolism in adults. The newborn kidney may not be capable of rapidly metabolizing the large gastrin load presented to it during these first hours of extrauterine life. Continued high secretion of gastrin by the G cell may also play a role in the elevated serum levels found. The low gastric acid secretion in response to these high gastrin levels may be due to decreased parietal cell responsiveness during this period of life. Decreased parietal cell mass could also be responsible. Finally, if the predominant gastrin molecule was not the G-17 moiety, decreased acid secretion would be expected.

Disturbances of perinatal carbohydrate metabolism in rats exposed to methylmercury in utero

Pregnant rats were given a single subcutaneous injection of methylmercuric chloride (at 4 or 8 mg/kg) on the ninth day of gestation. Foetal (2 days prenatal), newborn and postnatal (6 days post partum) animals from the methylmercury-treated mothers were investigated with respect to parameters of carbohydrate metabolism. In the absence of any physical abnormalities, foetal rats exposed to methylmercury in utero showed diminished concentrations of plasma glucose and liver glycogen concentrations and a lower hepatic glucose-6-phosphatase activity compared to control animals. Newborn rats from the methylmercury-treated mothers showed an impairment in glycogen mobilization in the first hours of extra-uterine life which was accompanied by a severe and protracted hypoglycaemic response. Postnatal rats exposed to methylmercury in utero exhibited higher liver glycogen concentration and decreased body weights compared to control rats. The results point to a derangement of perinatal carbohydrate metabolism in the offspring of pregnant rats exposed briefly to low doses of methylmercury during gestation (“metabolic teratogenesis”). The postnatal hypoglycaemic episode in exposed rats may contribute to the pathogenesis of the neurological disturbances revealed by these animals in later life.

Effect of Environmental Temperature on Glucose-induced Insulin Response in the Newborn Rat

Blood glucose and plasma insulin and glucagon concentrations were determined in full-term rats delivered by cesarean section and exposed to 37 degrees C. or 24 degrees C. environmental temperature during the first hours of extrauterine life. When newborn rats were maintained at thermal neutrality (37 degrees C.), a transient period of hypoglycemia of two hours occurred, associated with a rapid fall in plasma insulin and a rise in plasma glucagon concentrations. During cold exposure (24 degrees C.), the blood glucose level remained stable over the four hours studied; the decrease of plasma insulin was sluggish while the rise of plasma glucagon was unchanged. In newborn rats maintained at 37 degrees C., an intraperitoneal glucose load one hour after delivery produced a marked rise in blood glucose and plasma insulin concentrations one hour later. The distribution of experimental points suggested a sigmoidal dose-response curve. By contrast in newborn rats kept at room temperature (24 degrees C.) the same glucose load did not induce any increase in plasma insulin in spite of hyperglycemia. However, phentolamine resulted in pronounced plasma insulin rise in hypothermic newborns in response to glucose administration. From these observations it is concluded that the in-vivo unresponsiveness of the beta cells to glucose at birth, reported by others, is mainly due to the experimental conditions.

Radiologic evaluation of the premature newborn rabbit after pharyngeal deposition of surfactant

Premature rabbit fetuses were delivered by hysterotomy and, prior to the first breath, a concentrated homologous surfactant suspension was deposited in the pharynx. With repeated radiograms, the effect of this treatment was studied during the first two hours of extrauterine life. The lung aeration was quantitated with densitometry, and the chest expansion was assessed by measuring the inferior angle formed by the fourth ribs. In comparison with control animals, the treated animals demonstrated a greater chest expansion, and their lungs were significantly better aerated. Clinical application has to await further studies.

Lung expansion and the formation of the alveolar lining layer in the fullterm newborn rabbit.

Light and electron microscopic studies of lungs from fullterm newborn rabbits, 0-24 hours after birth, revealed a patchy alveolar air expansion during the first few hours of extra-uterine life. Fairly uniform aeration of alveoli was noted 6-24 hours after birth but minor "unexpanded" areas were still present after 24 hours. In the fetal pulmonary fluid as well as in the alveolar lining layer formed after the onset of breathing there are multiple large phospholipid complexes, and a discontinuous multilamellar surface film can be demonstrated in some alveoli from 2 hours after birth. Apparently, the neonatal adaptation of the rabbit lung is a protracted process, not even complete at the age of 24 hours.

Induction of enzyme activity during fetal development. The appearance of ornithine transcarbamylase activity in rat liver.

The activity of ornithine transcarbamylase, an enzyme of the urea cycle, has been measured in the liver of fetal, newborn, and adult rats in order to identify the time of development at which this aspect of liver function begins, and to elucidate the control mechanisms by which enzymes are induced during development. In the fetus, the activity of this enzyme reaches a peak immediately before birth and drops sharply during the first hours of extrauterine life. Enzyme activity increases in response to injected carbamyl phosphate. Once genetic competence is achieved, the hepatocyte is capable of responding rapidly and sensitively to metabolic stimuli such as the accumulation of the products of protein metabolism.

THE VENOUS PLASMA FREE AMINO ACID LEVELS DURING THE FIRST HOURS OF LIFE

SummaryDuring the first hours of extrauterine life the venous plasma of the fasting normal newborn shows a fast decline of valine, leucine, isoleucine, lysine and alanine levels, while the glycine level and the ornithine/arginine quotient seem to increase. These changes are not caused by urinary excretion and are the same as those found in calorie undernutrition.The fasting newborn of mothers with hypertension of pregnancy, who are underweight and short for gestational age, have increased levels of valine, leucine and isoleucine during the first hours after birth and a tendency towards a more rapid decline of the levels thereafter. The alanine and proline levels seem to “resist” the general decline during the initial fast. These changes in the homeostasis of plasma free amino acids are not due to short gestational period. They are the same as those found in protein deficiency.

Renal function of normal full-term infants in the first hours of extrauterine life: I. Infants delivered naturally and given a placental transfusion

Renal function in the immediate neonatal period was studied in 8 healthy full-term infants given placental transfusion by cord stripping. Great variations in urine flow rate, inulin and PAH clearance, osmolality, and osmolal and inulin U/P ratios were encountered. These did not correlate with systemic blood pressure, acid-base state, or arterial oxygen level. Until the underlying mechanisms are understood it is not possible to generalize about the renal function in the newborn infant.

CIRCULATORY CHANGES FOLLOWING BIRTH OF THE CALF AND THE EFFECT OF HYPOXIA.

Circulatory and ventilatory measurements were made during the course of 66 cardiac catheterizations in 20 unanesthetized Jersey calves, age two hours to eight weeks. The salient findings were: 1. The pulmonary arterial pressure was high during the first two to three hours of extra-uterine life (up to 80 mm Hg) and it decreased rapidly (30 to 40 mm Hg) during the next nine to ten hours. 2. The pulmonary ventilation appeared good, judging by the active appearance of the calves, the volumes of respired air, the arterial blood gases, and the ventilatory response to hypoxia. 3. The pulmonary blood flows in these calves were not higher in the first hours of life than on subsequent days, and there was little contribution to the pulmonary blood flow by a left to right shunt through the ductus arteriosus. 4. Hypoxia, if severe, could increase the pulmonary arterial pressure to systemic levels on the day of birth, but not in older calves. 5. Pulmonary vasoconstriction sometimes followed puncture of the aorta or other procedures in calves less than twelve hours old. The lability of the pulmonary blood vessels during the first hours of extra-uterine life suggested that large changes in pulmonary vascular tone also occur in utero.

REPARATIVE PHENOMENA IN LUNGS OF NEONATES WITH HYALINE MEMBRANES

Destructive changes have been described by others in the respiratory bronchioles, alveolar ducts, and alveoli associated with hyaline membranes in the lungs of infants who died in the first few hours of life. After 24 hours of extra-uterine life, cellular proliferative phenomena appear in these same areas and are almost always present after 48 hours of extra-uterine life. It is suggested that these represent a reparative process related to the early destructive changes associated with the formation of the hyaline membrane, rather than a purely reactive phenomenon associated with the formation of phagocytes involved in the removal of the membranes.

CAN INTRACRANIAL BIRTH INJURIES BE PREVENTED?

In the face of certain facts now definitely established by careful clinical study of the new-born infant and by thorough anatomic investigations made on stillborn infants and those dying within a few days after birth, we may well ask ourselves the question, Can intracranial birth injuries be prevented? Nystagmus can be observed in about 35 per cent of all babies born after perfectly normal labors, the incidence of this anomaly rising to almost 80 per cent in the first-born, and to 100 per cent in those with abnormal presentations. Retinal hemorrhages are discovered within the first twenty-four hours of extra-uterine life in probably more than 12 per cent of infants. Smaller and larger hemorrhages in the substance of the brain, outside of the fairly common pial and tentorial hemorrhages, are found at autopsy in about 65 per cent of all young infants. Lacerations in various dural folds, with or without