Showing papers on "Fetus published in 1972"

Development of mammalian sulfur metabolism: absence of cystathionase in human fetal tissues.

Abstract: Extract: Cystathionase activity was absent from human fetal liver and brain as early as 6 weeks of gestation. Hepatic methionine-activating enzyme (26 ± 3 nmoles/mg protein/hr) and hepatic cystathioninesynthase (21 ± 4 nmoles/mg protein/hr) were present (cf. 86 ±16 and 98 ± 19 nmoles/mg protein/hr, respectively, in mature human liver). All three activities were absent from the placenta. Human fetal liver contained higher concentrations of cystathionine (14 ± 2 $mUmoles/100 g wet weight) than mature human liver (0) and human fetal brain (4.0 ± 0.6 $mUmoles/100 g wet weight). Methionine-activating enzyme of human fetal brain, but not liver, showed a tendency to increase with development (coefficient of correlation was 0.62; 0.01 cysteine and liver > kidney > brain. Incorporation of 35S-l-methionine and 35S-l-cysteine incubated with minced liver from four human fetuses showed more active incorporation of methionine (11,836–15,045 dpm/mg protein) than cysteine (7,044–9,856 dpm/mg protein). Speculation: These studies suggest that cysteine is an essential amino acid in human fetuses and in infants for some time after birth, especially if they were born prematurely.

Carcinoembryonic Antigen in Patients With Different Cancers

Abstract: Carcinoembryonic antigen (CEA) is a cancer-specific antigen described by Gold in 1965. It is a glycoprotein present in malignant entodermal tissues, in fetal colonic mucosa, and in the plasma of patients with gastrointestinal tract cancers. We have measured plasma CEA levels in 346 patients using a new procedure which detects an ion-sensitive antigenic site in the carcinoembryonic molecule. Levels in 39 of 48 patients with gastrointestinal tract cancer and 90 of 281 with nonentodermally derived malignancies were abnormal. Following successful therapy CEA level returns to normal (colon, four of four; neuroblastoma, three of three). The identity between the antigen measured in the present study and the carcinoembryonic antigen of Gold has not been established. The assay appears to be useful in the follow-up of patients with cancer and may eventually be of diagnostic value in the asymptomatic patient.

The Ontogenesis of Human Fetal Hormones: I. GROWTH HORMONE AND INSULIN

Abstract: The content and concentration of immunoreactive growth hormone (GH) were measured in 117 human fetal pituitary glands from 68 days of gestation to term and in the pituitary glands of 20 children 1 month to 9 yr of age. Physicochemical and immunochemical properties of GH of fetal pituitary glands and GH from adult pituitary glands were indistinguishable by disc gel electrophoresis, immunoelectrophoresis, starch gel electrophoresis, and radioimmunoassay techniques. In the fetal pituitary gland, the GH content rose from mean levels of 0.44+/-0.2 mug at 10-14 wk of gestation, to 9.21+/-2.31 mug at 15-19 wk, to 59.38+/-11.08 mug at 20-24 wk, to 225.93+/-40.49 mug at 25-29 wk, to 577.67+/-90 mug at 30-34 wk, and to 675.17+/-112.33 mug at 35-40 wk. There was a significant positive correlation between growth hormone content of the pituitary and gestational age, crown-rump length, and the weight of the pituitary gland. The content and concentration (micrograms/milligram) of human growth hormone (HGH) in the fetal pituitary showed significant increments (P < 0.001) for each 4 wk period of gestation until 35 wk. Further increases in the HGH content were noted in pituitaries of children aged 1-9 yr (range of 832 to 11.211 mug). Immunoreactive GH was detected in fetal serum at a concentration of 14.5 ng/ml as early as 70 days gestation, the youngest fetus assayed. At 10-14 wk, the mean concentration of serum growth hormone was 65.2+/-7.6 ng/ml; at 15-19 wk 114.9+/-12.5 ng/ml; at 20-24 wk 119.3+/-19.8 ng/ml; at 25-29 wk 72.0+/-11.5 ng/ml; and 33.5+/-4.2 ng/ml at term. A significant negative correlation of serum growth hormone with advancing gestational age after 20-24 wk was observed (P < 0.001). In 17 fetuses paired serum and pituitary samples were assayed; no significant correlation between the concentration of serum GH and the pituitary content or concentration of GH was demonstrable. The serum concentration of chorionic somatomammotropin (HCS) in the fetus was unrelated to gestational age. Insulin (1-30 muU/ml) was detected in 42 of 46 fetal sera assayed. These data suggest that the appearance and development of the secretory capacity for GH by the human fetal pituitary gland coincides with developmental changes in the portal system and hypothalamus. Maturation of inhibitory central nervous system control mechanisms for secretion of GH may not occur until infancy.

Vestibular macular mapping in man.

Abstract: The normal histology and ultrastructure of the vestibular sensory regions are well known and have been previously described. In the mammalian vestibular maculae, a narrow strip, the striola, and large peripheral areas can be distinguished.'v2 Each vestibular sensory cell is equipped with a hair bundle consisting of many stercocilia and one k in~ci l ium.~ The orientation of the kinocilium determines the polarization of the hair b ~ n d l e . ~ Thc morphological polarization is the same over large areas, and its direction shifts along an imaginary line, which extends through the striola. In the macula utriculi the morphological polarization is directed from the periphery towards the s t r i ~ l a ; ' ~ ~ ~ ~ in the macula sacculi the opposite condition exists.lgG The bending of a hair bundle towards the kinocilium results in a depolarization of the hair ~ ~ 1 1 . ~ 9 ~ According to the pattern of the morphological polarization, a displacement of the whole statoconial membrane which covers the macula results in depolarization of some hair cells and hyperpolarization of others.

Cellular Development of Some Human Organs Before Birth

Abstract: The total amount of DNA and the protein/DNA ratio have been measured in the kidneys, heart, liver, and gastrocnemius muscles of 56 human fetuses and newborn infants of 13-42 weeks' gestational age. The total amount of DNA in each organ approximately doubled every week up to the 25th; thereafter the rate of increase was slower. The protein/DNA ratio in each organ increased rapidly in the last 10 weeks of intrauterine life. Before 30 weeks there was some increase in the protein/DNA ratio in the kidneys, heart, and gastrocnemius muscles, but no significant change in the liver. In 5 small-for-dates infants the protein/DNA ratio was normal, whereas the total DNA tended to be low.

Glucocorticoid Receptors and the Role of Glucocorticoids in Fetal Lung Development

Abstract: The cellular mechanism of glucocorticoid effects upon fetal lung was examined in studies of specific binding activity for corticosteroids Cytoplasm of fetal rabbit lung contains receptor sites for [3H]dexamethasone at a concentration of 043 ± 004 pmol/mg of cytosol protein, and the apparent dissociation constant for the binding reaction is 27 ± 04 nM The ability of various steroids to compete with labeled dexamethasone for binding to receptor correlates with their biologic potency The hormone-receptor complex formed in vitro at 0° binds with high affinity at 20° to isolated lung nuclei It is estimated that there are 9500 nuclear binding sites and 12,000 cytoplasmic receptor sites per fetal lung cell During the last 12 days of gestation in a rabbit, the concentration of cytoplasmic receptor in lung is constant and is 2- to 5-times greater than receptor-site concentration in fetal skin, kidney, heart, muscle, gut, liver, brain, thymus, and placenta These findings demonstrate that the early steps in the mechanism of glucocorticoid action in target tissues are present in lung cells, and suggest that these hormones accelerate fetal lung differentiation and surfactant production in animals by the induction of new protein synthesis mediated by receptor

Developmental Changes in Constriction of the Ductus Arteriosus: Responses to Oxygen and Vasoactive Agents in the Isolated Ductus Arteriosus of the Fetal Lamb

Abstract: Extract: Development of the constrictor response of the ductus arteriosus to O2 and selected vasoactive drugs (acetylcholine and bradykinin) was studied in 20 fetal lambs weighing 680–4800 g (90− to 150-day gestation). The isolated ductus arteriosus was perfused in vitro with Tyrode's solution at constant flow, temperature (38°), pH (7.3–7.4), and (30–40 mm Hg), and the mean pressure difference across the ductus was measured. Ductal resistance was calculated at different levels of (10–700 mm Hg), raised stepwise to produce dose-response curves. Three young fetuses failed to respond initially to O2 and in the other 17 the initial response occurred at progressively lower levels with advancing gestation. The maximal degree of constriction developed showed a progressive increase with advancing gestational age. At any given , both acetylcholine and bradykinin produced a further increase in resistance when added to the perfusion solution, but this further increase was independent of age. The level of at which an initial response occurred was decreased after exposure to acetylcholine but not bradykinin. Speculation: The ductus arteriosus of the fetal lamb constricts when exposed to oxygen. The initial level of at which this constriction occurs decreases, and the maximal degree of constriction increases, with advancing gestational age. The poor response to oxygen of the ductus arteriosus in the immature fetus may be the mechanism responsible for the high incidence of patent ductus arteriosus in premature infants. Constriction following-oxygen may be augmented by the exposure to acetylcholine or bradykinin.

Production and excretion of urea by the fetal lamb

Abstract: The urea production rate of the fetal lamb has been measured in 10 pregnant ewes studied who were free of operative stress. The measurement of the fetal urea production rate was made by utilizing an independent measurement of placental urea clearance by the infusion of urea tagged with radioactive carbon (14C) into the fetal circulation and the endogenous concentration difference for urea between umbilical arterial blood and maternal arterial blood. It was shown that the concentration difference of urea between umbilical arterial and maternal arterial blood is significantly elevated during the first four days of recovery from surgery, with a mean value of 0.06 mg/ml plasma water on the first day. By the fifth postoperative day this concentration difference has decreased to a mean value of 0.034, which does not change from the fifth to the twelfth postoperative days. This study demonstrates that urea is excreted across the placenta at a rate of approximately 0.54 mg/min/kg fetal weight. By comparison with the urea excretion rate of adult sheep, this is a high rate of fetal urea excretion. It was demonstrated that the urea excretion rate across the placenta could be increased threefold by an infusion of ammonium lactate into the fetus. Thus, the endogenous urea excretion rate of 0.54 mg/min/kg fetal weight does not represent the maximum rate of urea production for the fetus. The finding of a high urea production rate in fetal life is new and contrary to the common belief that nitrogen catabolism plays a minor role in fetal life. These studies demonstrate that as much as 25% of the fetal oxygen consumption could be accounted for by the catabolism of amino acids.

Development of myocardial sympathetic innervation in the fetal lamb.

Abstract: Extract: The hearts of ten fetal lambs with gestational ages ranging from 75 days to term (150 days) and of two neonatal lambs were studied by the Falck-Owman mono-amine fluorescence technique to determine the pattern of development of the sympathetic nervous system. At 75–85 days of gestation, no sympathetic fibers are present in the heart, but brightly fluorescent dopamine-containing cells are diffusely scattered throughout the myocardium. Between 75–85 and 100–110 days, large nerve trunks begin to grow in along the coronary arteries and small branches are first distributed to the coronary arteries and later to the myocardium. There is continued growth of sympathetic fibres and, by term, an extensive network exists that supplies a large number of myocardial cells. Some growth occurs after birth, and continued innervation probably persists for several weeks. These findings are helpful in explaining the physiological observations of increasing autonomic activity in the circulation of the fetal lamb, and they suggest that growth of myocardial sympathetic nerves is one of the final steps in development of cardiovascular control. Speculation: The innervation of the myocardium by sympathetic fibers is incomplete before birth in the lamb. If the same pattern of development is present in the human fetus and infant, it is very likely that the circulation of the premature infant lacks the ability to respond to stress through sympathetic stimulation.

Embryonic-Fetal Toxicity and Teratogenic Effects of a Group of Methacrylate Esters in Rats

Abstract: Monomers of five methacrylate esters and acrylic acid were administered at three dose levels to female rats on days 5, 10, and 15 of gestation. The incidences of resorptions, dead fetuses, gross abnormalities, and skeletal malformations are presented for each of these groups. Mean fetal weights also were determined for each group, and those of the monomer-treated groups were significantly smaller (P ≤ 0.01) than those of the untreated controls.

Effect of sustained maternal hyperglycaemia on the fetus in normal and diabetic pregnancies.

Abstract: The effect of prolonged maternal hyperglycaemia on fetal plasma glucose and insulin concentrations was investigated in eight normal and nine diabetic patients. It was found that under fasting conditions the fetal glucose concentration in gestational diabetic pregnancies tended to be lower than in normal pregnancies. Insulin measurements suggested that this may be due to fetal hyperinsulinism in the diabetic group. During glucose infusion, regardless of the degree of maternal hyperglycaemia, the fetal glucose concentration was limited in 12 out of 13 cases to less than 200 mg/100 ml, with only small differences between normal and diabetic pregnancies. It is proposed that the placenta prevents unlimited transport of glucose to the fetus; yet in diabetic pregnancies a sequence of increased maternal-fetal glucose transport, fetal hyperinsulinism, and fetal hypoglycaemia may contribute to the observed perinatal mortality.

Protein Absorption by the Intestine of the Fetal Rat in Utero

Abstract: Horseradish peroxidase (molecular weight, about 40,000) injected into the amniotic sacs in pregnant rats has been identified ultrastructurally, 6 to 18 hours later, within the fetal intestine in the absorptive cells and the underlying vascular endothelium. This indicates that macromolecular protein within amniotic fluid swallowed by the fetus can be absorbed and transported by fetal intestine, and may indicate that physiological compounds can be transported by this enteric route to contribute to fetal development.

Cholesterol Metabolism and Placental Transfer in the Pregnant Rhesus Monkey

Abstract: The placental transfer of cholesterol (5-cholesten-3β-ol) was investigated by giving pregnant rhesus monkeys cholesterol-1α-3H or cholesterol-4-14C and then determining the cholesterol specific activity (SA) in maternal serum and in fetal serum and tissues. An isotopic steady state was established in five pregnant animals by the daily feeding of a tracer dose of cholesterol-4-14C. Comparison of maternal and fetal serum cholesterol SA revealed that an average of 42.6% of the serum cholesterol in the term fetus originated by transfer from the maternal blood. The remainder presumably arose by fetal synthesis de novo. Fetal tissues had cholesterol SA equal to or slightly less than that of fetal serum, except for brain which had a SA only 5% that of fetal serum. In other studies a single intravenous dose of radioactive cholesterol was given to either mother or fetus in late pregnancy. The time for detectable passage across the placenta in either direction was between 4 and 24 hr. With maternal administration of the isotope, there was equilibration of maternal and fetal serum cholesterol SA after 10-12 days. With fetal injection of isotopic cholesterol, however, the maternal cholesterol SA never attained a level more than 5% of fetal SA. This indicated that the net cholesterol flux was strongly in the direction of mother to fetus. Serum cholesterol levels were significantly greater in maternal than in fetal serum (80.3±18.5 vs. 59.6±15.6 mg/100 ml). Maternal serum cholesterol concentration in the monkey was significantly lower in late pregnancy than during the puerperium. Studies of breast milk indicated that approximately two-thirds of milk cholesterol was transferred from the maternal blood.

Birth weight, fetal age and perinatal mortality

Abstract: 4 sets of data that give perinatal mortality rates by birth weight and duration of pregnancy have been studied to discover the relative contributions of birth weight and fetal age to perinatal mortality. 2 approaches are used: graphic representation and the Mantel-Stark method of indirect standardization. Consistently in all sets of data birth weight makes the predominant contribution to perinatal mortality. The contribution of fetal age seems to be notable only in the period around 37 to 42 weeks of gestation. The implications of these findings for prediction and prevention of pregnancy outcomes and for characterizing syndromes of fetal growth and maturity are noted. To raise birth weight could be an important therapeutic measure and should be attempted.(AUTHORS MODIFIED)

Sources of Plasma 17α-Hydroxyprogesterone in Human Pregnancy

Abstract: Sources of 17α-hydroxyprogesterone (17-OHP) in human pregnancy were studied by measuring its plasma concentrations in blood samples of umbilical artery (UA), umbilical vein (UV), retroplacental space (RPS), maternal ovarian (OV) and maternal peripheral vein (PV) of eight patients in mid-pregnancy and five patients at term. The following means and standard deviations (sd) of 17-OHP were found for term pregnancy: UV, 22.2 ± 2.8; UA, 14.0 ± 2.3; PV, 6.6 ± 0.6; OV, 24.5 ± 5.0; and RPS, 29.7 ± 3.8 ng/ml. The mean (±sd) 17-OHP plasma levels at mid-pregnancy were: UV, 15.7 ± 4.3; UA, 11.9 ± 3.6; RPS, 17.0 ± 6.2; OV, 11.5 ± 2.0; and PV, 2.3 ± 0.3 ng/ml. The ovarian vein and RPS 17-OHP plasma levels which were 7- and 4-fold above PV levels in both mid-pregnancy and at term indicate placental and ovarian secretion of 17-OHP. Taking the different blood flows into account, it appears that at term the bulk of 17-OHP is produced by the placenta. Administration of hydrocortisone to six patients prior to cesarea...