Showing papers on "Fetus published in 1971"

Diagnosis of the respiratory distress syndrome by amniocentesis

Abstract: Studies on 302 amniocenteses show that changes in phospholipids in amniotic fluid (PLAF) reflect those in the lung of the developing fetus. A sudden increase in lecithin concentration after 35 weeks heralds maturity of the pulmonary alveolar lining when respiratory distress syndrome will not occur should the fetus then be born. Clinical interpretation is made on a thin-layer chromatogram by inspection; a lecithin spot clearly larger than that of sphingomyelin marked pulmonary maturity in the fetus.

Enzyme Patterns in Fetal, Adult and Neoplastic Rat Tissues

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Studies on the Circulation of the Previable Human Fetus

Abstract: Extract: The circulation was studied in 33 previable human fetuses (12–272 g) delivered by hysterotomy, while the placenta was still attached. The umbilical vein (UV) and in some instances umbilical or carotid artery (FA) were cannulated. Fetal and maternal pH, PO2, and PCO2 were measured. Radionuclide-labeled microspheres (50 μ in diameter) were injected into the UV on one or more occasions from 1 to 36 min after delivery of the fetus. The distribution of the cardiac output (CO) was calculated from the relative amounts of radioactivity in each organ. In 11 fetuses, FA blood samples were withdrawn during microsphere injection, and CO and actual organ blood flows were measured. With advancing gestational age (10–20 weeks) there was an increase in total inferior vena caval return from 64 to 75% of CO. The proportion of CO to the placenta increased from 17 to 33% and to the gut from 5.5 to 9.2%. Superior vena caval return decreased from 32 to 23%, and the percentage of CO to the kidneys fell from 6.5 to 3.2%. In those fetuses in which repeated observations were made, there was a fairly uniform decrease in proportion of CO distributed to the placenta, probably owing to umbilical vessel constriction. This deterioration was not reflected by UV blood gases which in fact showed a decrease in PCO2 and rise of PO2, when FA showed a rise of PCO2 and fall in PO2 and pH. Associated with the fall in FA pH there was an increase in the proportion of CO to the brain, myocardium, and adrenals. The proportion of CO to the brain increased significantly with increase of FA PCO2. Speculation: The circulation of the previable human fetus may be studied at the time of hysterotomy. It is most important to realize that, even though umbilical venous blood gases may appear to reflect good physiological function, umbilical flow may be markedly decreased. This must be taken into account in all attempts to study placental function.

Bacterial infection in the fetus and newborn.

Abstract: The significance of potentially harmful influences on the fetus and newborn may be judged in two ways. A direct effect on perinatal mortality is the more easily measured; while subtle damage at a period of very rapid growth may have lasting effects, not always immediately obvious, on the ultimate size and function of organs in survivors. Bacterial infection continues to exert an influence in both ways in the perinatal period, for the impact of antibiotic and chemotherapeutic drugs has been less dramatic than at other ages, and humoral and cellular defence mechanisms may differ qualitatively and quantitatively. It is difficult to assess the true extent of this problem from the recent literature, largely because criteria for diagnosis are often inexact. It is not always clear for instance whether septicaemia has been diagnosed on blood culture taken from peripheral veins, or from the umbilical vein which may give false positive results (Lipsitz and Cornet, 1960). Even the morbid anatomist's interpretation of his necropsy material is dependent to some extent on the clinician's diagnostic efforts, as inflammatory change may be minimal when death has been rapid from profound bacterial toxaemia. Previous estimates of bacterial infection among stillbirths range from 3-15%, and among neonatal deaths from 10-20% (Claireaux, 1958), and there may well be racial and geographical variations dependent on social and economic conditions. Even allowing for the fact that neonatal infection is now being sought more energetically, McCracken and Shinefield (1966) suggest a recent increase in the mortality from septicaemia and meningitis. Thus, it may be pertinent to review the various aspects of bacterial and host defence at a time when the fetus can no longer be considered inviolate from marauding Man, and when increasing technical expertise is being lavished on infants who make an untimely exit from the uterus. The growing interest in this subject in recent years is illustrated by the fact that a request for a Medlars search of the literature from 1963 to the middle of 1969 resulted in the retrieval of 17,147 relevant items. The computer rebelled at the size of this 'print-out' so relieving the writer of a 'readout' which would have extended into senescence. Those interested will therefore be deprived of a complete coverage of the problem, and subjected to a personal and language bias. Much reliance has been placed on previous review articles, so that often, and most regrettably, earlier original work goes unacknowledged.

Tumor Immunity in Hamsters Immunized with Fetal Tissues

Abstract: Hamster and mouse fetal cells were shown to contain antigen cross-reactive with simian virus 40 (SV40)-induced tumor specific transplantation antigen in stimulating a surface reactive, cytostatic (C) antibody against SV40 tumor target cells in diffusion chambers. The antibody was synthesized when 10-day, but not 14-day, irradiated fetal cells were injected into adult, syngeneic hamsters, and these animals were subsequently found to exhibit immunity to SV40 tumor cell challenge. The spectrum of fetal antigens present in hamster fetus was extended to adenovirus 31-stimulated tumors, and the experimental data afford an explanation of the variability previously noted in the status of immunity to tumor challenge in hamsters immunized with syngeneic fetal tissues. The failure of unirradiated fetal cells to induce transplantation immunity was correlated in this work with the development of embryomas or teratomas at the site of immunization. Males responded to fetal immunization better than did female animals although multiparous, pregnant hamsters developed C antibody during pregnancy, and lost it post-partum. The role of fetal antigenic expression in cancer and cancer immunology is considered in relation to these findings.

Adult Hemoglobin Synthesis by Reticulocytes from the Human Fetus at Midtrimester

Abstract: The synthesis of adult-type hemoglobin was measured in small samples of peripheral blood cells from 9- to 18-week human fetuses. Hemoglobin indistinguishable from hemoglobin A was identified by ion-exchange chromatography, electrophoresis at p H 8.6, tryptic peptide analysis, and the insensitivity of its synthesis to the action of O-methylthreonine. Synthesis of hemoglobin A accounted for 8 to 14 percent of total hemoglobin synthesis and was demonstrated in as little as 10 microliters of fetal blood. These studies provide sensitive methods for the detection of β chain types in hemoglobin synthesized by the human fetus at midtrimester. If methods to obtain small quantities of fetal blood at midtrimester become available, these techniques should be applicable to the antenatal detection of sickle cell anemia and related hemoglobinopathies.

Human IgG subclasses in maternal and fetal serum.

Abstract: . The four subclasses of IgG were quantitatively determined in a panel of fetal and maternal sera. It was found that all four subclasses pass from the mother to the fetus.

The effects of maternal hypoxia and hyperoxia upon the neonatal pulmonary vasculature.

Abstract: The fetal and newborn pulmonary artery has thickened media by comparison to that of the older infant. In this study we investigated the proposition that chronic maternal hypoxia during the latter part of gestation might induce further thickening of the neonatal pulmonary artery media. Relative medial thickness was determined by the ratio of the arterial media to external diameter. The mean ratio of small pulmonary arteries of progeny of hypoxic mothers was significantly thicker in each size group between 50 and 150 microns as compared to those born to mothers who spent their gestation in air or hyperoxic environments. Medial hypertrophy was most pronounced in the smaller arteries of the hypoxic group; no intersize variations were found between the control or hyperoxic groups. Medial thickness decreased in all arteries through 2 weeks of age; this decrease was greatest in control and hyperoxic arteries. The possible relationship of hypertrophied pulmonary arterial media and abnormally increased neonatal pulmonary vascular resistance is discussed.

Evidence for independent regulators of organ maturation in fetal rabbits

Abstract: The degree of organ development bears a relationship to gestational age, but in a given infant not all organs need be at the same stage of development. The range of variation of organ maturation can be best studied in an animal with a large litter, such as the rabbit, in which gestation can be precisely timed. Body weight, ossification centers, and lung "maturity," defined as distensibility and stability on deflation, were all measured. Marked variations within a litter allowed study of the relationships between them. Body weight and the number of ossification centers were closely correlated at the same gestational age (R = 0.88, p 001). Ossification centers were less well correlated with gestational age. Lung "age," on the other hand, was more closely related to gestational age than body weight. A single injection of the fetus with 9-fluoroprednisolone, a glucocorticoid, at 24 days resulted in an acceleration of lung maturation, defined in terms of distensibility and the presence of surfactant by 26 to 27 days. No increase in lung weight took place. Similarly, the glucocorticoid had no effect on body size or the number of ossification centers, suggesting that regulators of maturation of these organs are independent.

Control of Glucose Metabolism in the Human Fetus and Newborn Infant

Abstract: Publisher Summary As normal human gestation progresses, the secretion of a hormone that is unique to the trophoblast—human placental lactogen—begins early in pregnancy and increases toward term, and the concentration of this hormone in maternal plasma rises progressively. In association with the high plasma levels sustained at term, resistance to the normal enhancement of glucose uptake by insulin develops in pregnant women. Thus, the rate of glucose metabolism by the fasting pregnant woman declines, and the decreased maternal uptake of glucose helps to preserve the fasting plasma level of glucose even though it diffuses continuously to the fetus. Although insulin resistance can be demonstrated in late pregnancy, normal glucose tolerance is maintained; after the ingestion of glucose, the plasma insulin response is enhanced. Thus, at the end of gestation, a hormonal factor other than placental lactogen causes an excessive insulin response to glucose stimuli. Throughout pregnancy, there is a net placental diffusion of glucose from the mother to the fetus as long as the mother remains either normoglycemic or hyperglycemic; but the protein hormones which could participate in the control of fetal glucose metabolism are transferred poorly.

Fetal bile salt metabolism: I. The metabolism of sodium cholate-14C in the fetal dog

Abstract: Cholate metabolism was studied in fetal dogs 1 wk before term and was compared with cholate metabolism in adult dogs. Tracer amounts of sodium cholate-14C were administered to the fetus in utero by intravenous infusion over 6 hr. Fetal plasma disappearance, biliary excretion, tissue distribution, and placental transfer of cholate were measured over 10 hr. Infused cholate-14C was cleared rapidly from fetal plasma principally by the fetal liver and to a minor extent by placental transfer to the mother. The taurine conjugate was formed in the fetal liver and was excreted into the proximal small intestine via the biliary tree. Indirect evidence for the functioning enterohepatic circulation of bile salt in the fetus was obtained. Comparison with the results of similar experiments in adult dogs showed that the fetal liver was almost as efficient as the adult liver in the uptake, conjugation, and excretion of tracer amounts of cholate-14C. The maximal rate of excretion of radiolabel attained by the fetus was somewhat slower than in the adult (82.8 ±1.4% and 96.1 ±4.0% [mean ±SE] of the infusion rate, respectively), and the proportion of the total dose excreted by the fetal liver during 10 hr was smaller (81.4 ±1.3% vs. 96.6 ±4.4%). This difference could be only partly accounted for by placental transfer (2.8 ±0.6% of the fetal dose). Labeled cholate and taurocholate were excreted by the fetus at similar rates, which suggests that, under the conditions of study, conjugation had little influence on the rate of transfer of cholate across the liver cell. It is concluded that the fetal dog, 1 wk before birth, has a remarkably mature and efficient mechanism for the uptake and excretion of cholate.

A-V differences of free fatty acids and glycerol in the ovine umbilical circulation.

Abstract: Conclusions1. Measurement of venous-arterial differences across the umbilical circulation of the sheep fetus in utero and across the maternal uterine circulation in the chronic animal preparation shows no significant passage of free fatty acids to the fetus. This is true despite relatively high maternal blood free fatty acid concentrations. There is a small venous-arterial difference of glycerol across the umbilical circulation; this is, however, sufficient to account for only a small portion of the fetal oxygen consumption due to substances other than glucose. Free fatty acids and glycerol therefore do not appear to constitute a significant part of the metabolic fuel supplied by the mother to the sheep fetus in utero.2. The fetuses of fasted ewes show an elevation of blood free fatty acid and glycerol concentrations. Measurements of venous-arterial differences across the umbilical circulation indicate that this free fatty acid and glycerol rise is of fetal origin.3. Fetal infusion of norepinephrine resul...

Cytomegalovirus mononucleosis in a first trimester pregnant female with transmission to the fetus

Abstract: An understanding of the pathogenesis of congenital cytomegalovirus (CMV) infections is hampered by the fact that the majority of adult infections are subclinical. This prevents documentation of the time of fetal infection. In the instance described, a 17-year-old pregnant female developed cytomegalovirus mononucleosis during her first trimester. CMV was recovered from her convalescent urine at 12 weeks9 gestation and from amniotic fluid at 21 weeks9 gestation. Following a therapeutic abortion at 22 weeks9 gestation, CMV was recovered from multiple fetal organs. Cord serum contained 14 mg/100 ml IgM which is elevated for a 22-week fetus. The IgM fraction of the cord serum contained specific CMV antibodies as demonstrated by indirect hemagglutination and indirect immunofluorescence techniques. This suggests that, under abnormal circumstances such as intra-uterine infections, fetuses may be capable of synthesizing detectable levels of specific IgM antibodies as early as 22 weeks9 gestation.

Ontogeny of heart-rate controls in hamster, rat, and guinea pig.

Abstract: ADOLPH, E. F. Ontogeny of heart-rate controls in hamster, rut, and (G~rn pi+ Am. J. Physiol. 220(6): 1886-1902. ,\ 1971.-The aim was to ascertain to what extent the resting heart rate at various ages was subject to autonomic influences. Three drugs were agents for blocking or for enhancing these influences. Fetuses in utero were drug injected while the mother was under anesthesia and fetal electrocardiograms were being recorded. Infants and adults were unanesthetized and restrained; all were kept at 37 C body temperature. Isoproterenol (a catecholamine) accelerated the heart in fetal stages. However, a certain fraction of individuals did not respond in fetus and early infant. Propranolol (an adrenergic blocker) decelerated the heart in all stages tested. Atropine (a chclinergic blocker) accelerated the heart in most postnatal stages (hamster, rat) and also in late prenatal stages of guinea pig. Amounts of acceleration usually increased with age, but in rat decreased in adult stages. In hamster the catecholamine effect was suppressed in early infancy. In general, adrenergic influences upon heart rates were present at earlier ages than cholinergic influences.

Onset of Lymphocyte Function in the Developing Human Fetus

Abstract: Extract: Lymphocytes capable of responding to phytohemagglutinin (PHA) were present in human fetal thymus tissue by 12-week gestational age and in spleens 2–4 weeks later. In spleens, establishment of the PHA response was associated with the appearance of small lymphocytes in cuffs surrounding central arterioles. Speculation: Onset of PHA responsiveness in lymphocytes obtained from the embryonic thymus precedes that of the spleen. It would be of particular interest to know when bone marrow cells and lymph node lymphocytes start to show this function.

Effects of Gestational Age, Birth and Feeding on the Insulinogenic Response to Glucose and Tolbutamide by Fetal and Newborn Rat Pancreas

Abstract: Perinatal maturation of the pancreatic beta cells was studied in the rat. Insulin synthesis proceeded rapidly be tween the twentieth gestational day and the third postnatal day. The insulin concentration in the pancreas and the amount of insulin available per gram of body weight reached a maximum sixty hours after birth and then decreased slowly toward the values observed in the adult rat. The pancreatic beta cells became responsive to glucose and to tolbutamide during the twenty-third day after fertilization, This phenomenon seemed to be related to the gestational age and not to act of birth or to feeding, although feeding appeared to increase the insulinogenic response to glucose.