Spectrophotometric Analysis in Umbilical Cords of Infants with Meconium Aspiration Syndrome

We compared spectrophotometric analysis of the umbilical cords of infants with meconium aspiration syndrome (MAS) or with meconium-stained amniotic fluid (MSAF) and healthy infants. In a prospective study, 15 infants with MAS and 37 infants with MSAF were enrolled. Twenty healthy infants formed a control group. The absorption peak of umbilical cords with meconium was significantly higher in the infants with MAS or MSAF than in controls. Spectrophotometric analysis of the umbilical cords with meconium may be useful to identify developed neonates with MAS or MSAF.     

Microscopic changes induced by the intratracheal inoculation of amniotic fluid and meconium in the lung of neonatal rats

Meconium aspiration syndrome is a major contributor to neonatal respiratory distress in infants and it has been sporadically recognized in neonatal animals. This investigation was designed to study the short and long term effects of meconium and amniotic fluid in the lungs of neonatal rats. Seven-day-old rats (n = 123) divided in three groups were intratracheally inoculated with saline solution, amniotic fluid or meconium. Rats were euthanatized on 1, 3, 7, 14, 28, 56 and 112 postinoculation days (PID) and the lungs were examined by light microscopy. Saline solution did not induce any change while amniotic fluid elicited only a mild foreign body response which disappeared by PID 14. In contrast, meconium induced an exudative alveolitis characterized by recruitment of neutrophilsn in the bronchoalveolar spaces. Meconium also induced atelectasis, hyperinflation and thickening of alveolar septa all of which had disappeared by PID 14. Starting at PID 7, neutrophils were progressively replaced by macrophages, giant cells, and some fibroblasts. There were sporadic foci of mineralization starting at PID 14 and lasting up to PID 112. Some mineralized foci became lined with cuboidal epithelial cells at PID 28. Meconium was slowly degraded but still evident by PID 112. It was concluded that inoculation of meconium in neonatal rats induces acute microscopic changes typical of meconium aspiration syndrome. The long term lesions induced by meconium consisted of persistent multifocal histiocytic alveolitis and bronchiolitis reaction with occasional foci of calcification.     

The role of fetal urinary excretion in the transfer of ethanol into amniotic fluid after maternal administration of ethanol to the near-term pregnant ewe

The objective of this study was to determine whether fetal urinary excretion is a major route of ethanol transfer into the amniotic fluid surrounding the fetus following maternal administration of ethanol. Conscious instrumented pregnant ewes between 130 and 137 days' gestation (term, 147 days) with (n = 3) or without (n = 3) a catheter in the fetal bladder were administered 1 g ethanol/kg maternal body weight as a 1-h maternal intravenous infusion. Maternal blood, fetal blood, and amniotic fluid samples were collected at selected times, and fetal urine was collected continuously from the bladder-cannulated fetus during the 14-h study for the determination of ethanol concentrations. Fetal urinary excretion of ethanol occurred, and the total amount of ethanol excreted represented 0.30 +/- 0.07 (SD)% of the maternal ethanol dose. The renal clearance of ethanol by the fetus was 0.43 +/- 0.06 mL/min. The pharmacokinetics of ethanol in the maternal-fetal unit and the amniotic fluid for the bladder-cannulated fetal preparation were similar to the data for the nonbladder-cannulated preparation. The data indicate that fetal urinary excretion of ethanol is a secondary route of ethanol transfer into the amniotic fluid. It would appear that diffusion of ethanol across membranes from the maternal and fetal circulations is a major route of ethanol transfer into this intrauterine compartment.     

Measuring fetal and maternal temperature differentials: a probe for clinical use during labour

The healthy fetus maintains a higher temperature than that of its mother during gestation and labour. This results from the thermal balance between the heat generated by the fetus and the heat loss to its maternal surroundings. The heat loss can be by heat exchange via blood flowing in the umbilical cord and placenta, and via conduction through the fetal skin and amniotic fluid to the maternal wall. The temperature difference between the fetal and maternal tissue may reflect the metabolic state of the fetus and the magnitude and changing patterns of placental blood flow during labour. Physiological changes, such as those induced by epidural analgesia, and fetal infection have been shown to exhibit an increase in the absolute temperature. An intrauterine probe, previously used for non-invasive ECG detection, has been equipped with temperature sensors that measure fetal and maternal skin temperature in utero. Laboratory tests to characterize the performance of the probe reveal that absolute and differential temperatures can be resolved to around 0.01° C with a thermal time constant of approximately 9 s. Ideally the probe body should have infinite thermal insulation or thermal shunting across the probe will occur reducing the measured temperature difference. In this initial probe design, a high thermal isolation between sensors has been achieved but is not perfect, resulting in around 85% of the actual temperature difference across the probe being registered. Average feto-maternal differences of 0.2° C have been measured in a clinical investigation.     

Tracheoesophageal malformation: pathogenetic evidence provided by two cases

BACKGROUND: The aim of this observational study is to examine cases of upper respiratory atresia, in an effort to seek pathogenetic evidence suggestive of either a primary defect in embryogenesis or of a secondary etiology. METHODS: Archival material of 412 fetal and perinatal autopsies with congenital malformations was reviewed in an effort to identify infants with complete upper airway obstruction without tracheoesophageal (TE) communication. Histological sections of the upper and lower respiratory tract were examined, seeking evidence of previous amniotic fluid or meconium aspiration, indicated by the presence of amniotic squamous epithelial cells, lanugo hair, or bile-stained meconium in the airways. Immunohistochemical stain for epithelial membrane antigen (EMA) and high-molecular-weight cytokeratin (CK1) were used to identify amniotic fluid and keratinizing squamous epithelial cells. RESULTS: Eight infants with upper airway obstruction were identified, three of them without a TE communication. Two of the latter, one infant with multiple atresia born at 34 weeks gestation and another with tracheal atresia born at 32 weeks, presented evidence of amniotic fluid aspiration in their lungs. CONCLUSIONS: Evidence of amniotic fluid aspiration in the above two cases indicates that there had been a previous patency of the upper respiratory pathway, since the absence of a TE fistula excludes any communication with the oronasal cavity. This implicates a secondary pathogenesis for at least some cases of upper airway obstruction.     

Meconium enhances platelet-activating factor and tumor necrosis factor production by rat alveolar macrophages

Meconium aspiration syndrome (MAS) frequently results in inactivation of surfactant, persistent pulmonary hypertension (PPHN) and respiratory failure among newborn infants. Inflammation and inflammatory mediators play an important role in MAS. Since alveolar macrophages are thought to be very important cells in the pathogenesis of various inflammatory diseases, we evaluated whether meconium could stimulate rat alveolar macrophages to generate platelet-activating factor (PAF) and tumor necrosis factor (TNF)-alpha in vitro. We also examined the response to A23187 (calcium ionophore), 1-0-Hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (synthetic PAF) and dexamethasone on meconium-induced release of PAF and TNF-alpha. PAF and TNF-alpha concentrations from supernatant fluid were measured after high-performance liquid chromatography purification by specific radioimmunoassay, and TNF-alpha concentrations were determined by using an enzyme-linked immunosorbent assay. Our results showed that alveolar macrophages exposed to meconium could enhance PAF and TNF-alpha production in a dose (0.1, 1, 5 and 10%, P<0.01)-dependent way. In the presence of A23187, the capability of meconium to stimulate PAF production was further enhanced in the supernatant fluids. Furthermore, treatment with synthetic PAF significantly increased the generation of TNF-alpha in response to meconium. On the other hand, dexamethasone effectively inhibited both PAF and TNF-alpha production stimulated by 5% meconium (P<0.01, P<0.01; respectively). We suggest that alveolar macrophages and PAF, TNF-alpha play an important role in the pathogenesis of lung injury and severe complications in MAS. Furthermore, the protective effect of glucocorticoids in MAS could be due, at least in part, to a suppression of PAF and TNF-alpha generation.     

Prenatal diagnosis of congenital anomalies in an intrauterine growth retarded fetus

Summary Chromosome analysis of amniotic fluid cells and amniotic fluid alpha-fetoprotein determinations were used to investigate a fetus with severe intrauterine growth retardation in the third trimester. The karyotype was 47,XY,18+ and increased alpha-fetoprotein levels indicated the presence of congenital malformations. We suggest that when severe fetal growth retardation is detected early in the antepartum course, amniotic fluid alpha-fetoprotein and amniotic fluid cell chromosome studies be done to determine if congenital anomalies may be an etiological factor.     

羊水栓塞妊娠大鼠血清中PLA2和PAF的水平变化研究

摘要 目的：探讨羊水栓塞妊娠大鼠血清中PLA2和PAF的水平变化。方法：30只健康妊娠大鼠均分为生理盐水组（A组）、羊水组（B组）及羊水胎粪混合组（C组）。将健康妊娠大鼠麻醉,麻醉效果生成后,全部切除大鼠子宫后关腹,分离出左颈总动脉,并将二通道生理记录仪与其连接,连续监测血液动力学指标,随后将生理盐水、羊水和羊水胎粪混合液腹腔静脉注射于大鼠,1小时后取大鼠肺组织,用HE、APK染色结合CK16免疫组织化学法来检测模型是否制作成功。实验前后1小时两个取血点时,在制备好的羊水栓塞模型大鼠左颈动脉插管处各取1 mL血。采取酶联免疫检测法,测定血清、羊水及羊水胎粪混合液中 PLA2、PAF 的含量。获得的数据用SPSS 20.0软件进行处理,采用配对 t 检验、协方差分析及相关回归分析对血清PLA2、PAF 的浓度进行分析。结果：B组和C组的3个血液动力学指标（动脉收缩压、舒张压及平均动脉压）均显著低于A组（P<0.05）,而B组与C组的4个血液动力学指标均无显著性差异（P>0.05）。同时,A组、B组与C组之间在心率改变方面无显著性差异（P>0.05）。HE染色中,B组与C组大鼠的肺间质显著变宽,且有充血、水肿及炎性细胞浸润,而A组无此现象。AMP染色中,B组和C组大鼠的肺小管中可见被染成蓝色的不定形物质和桃红色的角化鳞状上皮,而A组无此现象。CK16染色中,B组和C组大鼠的肺小管中,可以看到被染成黄色的颗粒和鳞状上皮,而A组无此现象。实验1小时后所取血液中,B组和C组的PLA2与PAF的含量显著高于A组（P<0.05）,且C组中升高程度更大。妊娠大鼠羊水与羊水胎粪混合液中均检测到PLA2和PAF,且羊水胎粪混合液中二者的含量均高。实验1小时前所取的血液中,PLA2和PAF浓度无相关性（P=0.762,R=0.012）,而实验1小时后所取血液中,PLA2和PAF浓度呈正相关关系（P=0.002,R=0.437）。结论：羊水栓塞妊娠模型大鼠羊水和胎粪中均有PLA2和PAF,且实验1小时后所取血液中,PLA2和PAF含量在B组和C组中显著高于A组,说明羊水和胎粪中含有使PLA2、PAF水平增高的刺激因子。     

Meconium-stained amniotic fluid activates polymorphonuclear leukocytes ultrastructural and enzyme-cytochemical evidence

The purpose of the present study was to demonstrate morphological evidence that meconium-stained amniotic fluid activates polymorphonuclear leukocytes. We used Boyden chamber techniques to determine the chemotactic activity of meconium-stained amniotic fluid for leukocytes, and ultrastructural enzyme-cytochemistry for peroxidase and alkaline phosphatase to characterize the leukocyte features induced by contact with meconium-stained amniotic fluid. Amniotic fluid with meconium staining enhanced migration of leukocytes. These leukocytes exhibited more numerous cytoplasmic processes and more prominent phagosomes compared to peripheral blood leukocytes. Peroxidase and alkaline phosphatase activity were evident on the phagosomal membranes. Our results indicate that meconium-stained amniotic fluid activates or stimulates polymorphonuclear leukocytes. Meconium-stained amniotic fluid induced leukocyte activation might play important roles in the pathophysiology of initiation of term labor or of the meconium aspiration syndrome.     

Prenatal diagnosis in 200 pregnancies with a 1-in-4 risk of cystic fibrosis

Summary Prenatal diagnosis of cystic fibrosis was performed in 200 pregnancies with a 1-in-4 risk, and was based on significant modifications in amniotic fluid taken at 17, 18, 19 weeks of pregnancy, of six enzymatic assays: gamma-glutamyl-transpeptidase, aminopeptidase M, and alkaline phosphatase (total and isoenzymes). On the basis of normal values, normal outcome was predicted in 135 pregnancies reaching term, all the babies were normal. On the basis of significantly abnormal enzymatic values, an affected fetus was predicted in 56 pregnancies, 53 were terminated, and 3 went to term; the infants were affected. There were discrepancies in enzymatic values in nine cases, in eight cases normal outcome was predicted, six babies were normal and two were affected; in one case an affected baby was predicted, the pregnancy went to term and the baby is normal. Criteria giving evidence for cystic fibrosis in fetuses have been described: macroscopic observation of a typical meconium ileus, significant increase of albumin content in the meconium, and PAS-positive mucus-like material in some pancreatic acini. Using these criteria, diagnosis of cystic fibrosis has been confirmed in all the examined fetuses. The recurrence rate of cystic fibrosis was 22.5% in 147 diagnoses in which the index case had cystic fibrosis without a history of meconium ileus at birth, but was 47.5% when the index case had meconium ileus. The results of the study suggest that prenatal diagnosis of cystic fibrosis can be performed with an accuracy of 98%.     

Surfactant protein A modulates the lipopolysaccharide-induced inflammatory response related to preterm birth

Surfactant protein A (SP-A) functions in homeostasis of lung surfactant and in innate immunity. SP-A is secreted by the fetal lung into amniotic fluid. Additionally it has been detected in gestational tissues. We propose that SP-A influences intrauterine inflammation that is commonly associated with preterm birth, the main underlying cause of neonatal mortality and morbidity. We used our previously established mouse model of LPS-induced preterm birth of live-born pups to investigate the role of SP-A in preterm birth. Mice overexpressing rat SP-A (rSP-A) under the control of human SP-C promoter were used. Cytokine concentrations in maternal and fetal serum and in amniotic fluid and mRNA levels of several inflammatory mediators in lungs and in intrauterine tissues were quantified using Cytometric Bead Array and RNase Protection Assay, respectively. Higher levels of SP-A mRNA were observed in fetal lungs and intrauterine tissues of rSP-A mice compared with wild-type. Using Western blot we detected excess of SP-A protein in fetal lung and in amniotic fluid of rSP-A animals. Despite some differences in the basal levels of TNF-α and IL-10 between rSP-A and wild-type animals, there were no differences in the duration of pregnancy. However, the levels of TNF-α, IL-10 and some other inflammatory mediators in intrauterine tissues and in amniotic fluid differed significantly between the mouse lines after maternal LPS given at 17 dpc. We conclude that SP-A modulates the levels of intrauterine inflammatory mediators involved in preterm birth and may contribute to inflammatory processes related to spontaneous preterm labor.     

Clinical proteomics in obstetrics and neonatology

Clinical proteomics has been applied to the identification of biomarkers of obstetric and neonatal disease. We will discuss a number of encouraging studies that have led to potentially valid biomarkers in the context of Down's syndrome, preterm birth, amniotic infections, preeclampsia, intrauterine growth restriction and obstructive uropathies. Obtaining noninvasive biomarkers (e.g., from the maternal circulation, urine or cervicovaginal fluid) may be more feasible for obstetric diseases than for diseases of the fetus, for which invasive methods are required (e.g., amniotic fluid, fetal urine). However, studies providing validated proteomics-identified biomarkers are limited. Efforts should be made to save well-characterized samples of these invasive body fluids so that many valid biomarkers of pregnancy-related diseases will be identified in the coming years using proteomics based analysis upon adoption of ‘clinical proteomics guidelines’.     

The design and development of a biosensor to measure the concentration of meconium in amniotic fluid

Meconium aspiration syndrome occurs in 0.2% to 1% of all deliveries and has a mortality rate as high as 18%. The disease is responsible for 2% of all perinatal deaths. Meconium may be classified as being thick or thin, but this assessment is normally performed visually by clinicians. A "meconiumcrit" analysis has been developed to objectively define the concentration of meconium. However, this analysis does not provide real-time continuous readings. This study focused on the design and development of a sensor to provide an objective, continuous, real-time assessment of meconium thickness. Meconium has an absorption spectrum centered at 410 nm and observes Beer's law. Blue light centered at 430 nm was delivered through meconium solutions, and a photodiode translated the strength of the incoming light into a voltage. This voltage was analyzed by a microcontroller to determine the concentration of meconium.     

Changes in lung liquid dynamics induced by prolonged fetal hypoxemia

Our aim was to determine the effect of prolonged fetal hypoxemia, induced by reduced maternal uterine blood flow (RUBF), on fetal lung liquid secretion, flow, and volume. In chronically catheterized fetal sheep, lung liquid volume (VL) and the secretion rate of lung liquid (Vs) were measured before and after a 24-h period of either RUBF or normoxemia. Tracheal fluid flow and the incidence of fetal breathing movements (FBM) were measured before, during, and after the 24-h period. In normoxic control fetuses Vs was not significantly altered. After 24 h of RUBF, Vs was significantly (P less than 0.005) reduced compared with pre-RUBF values. During 24 h of RUBF the incidence of FBM declined initially but returned to control values after 12-16 h. In seven of eight fetuses, over the 12- to 24-h period of RUBF, large amounts of liquid (22.7-62.6 ml) were drawn into the lungs during FBM, resulting in a net movement of amniotic fluid into the lungs. During the 18- to 24-h period of RUBF, changes in the incidence of FBM were found to be significantly and positively correlated (r = 0.86, P less than 0.005) with the changes in VL that occurred over the 24-h period. Thus, prolonged RUBF can result in the inhalation of large volumes of amniotic fluid by the fetus, which could be a cause of in utero meconium aspiration.     

Simplified Induction of Labour for the Patient with a Dead Baby in Utero

The problem posed by the presence of a dead fetus in utero after the first trimester is important because of the psychological attitude of the patient and the danger of hypofibrinogenemia. In the past, induction of labour in these patients has often been difficult, and surgery has had to be undertaken to empty the uterus.In these patients, labour was induced by inserting a needle with a trocar through the abdominal wall under local anesthesia into the amniotic sac. Approximately 200 ml. of amniotic fluid is withdrawn and replaced with a slightly larger amount of 20% saline solution. Labour began within 24 hours and delivery occurred within the next 14 hours. There have been no complications or failures with this technique in the cases reported in the literature.     

Prenatal Diagnosis of Tay-Sachs Genotypes

Hexosaminidase activity was determined in cultured and uncultured amniotic fluid cells taken from seven pregnant women who had previously given birth to infants with Tay-Sachs disease. Complete deficiency of hexosaminidase A was found in one case, indicating a Tay-Sachs fetus. The diagnosis was confirmed on examination of various tissues after therapeutic abortion. Of the other six cases three were considered heterozygous and three homozygous normal. These diagnoses were confirmed postnatally on examination of cord blood leucocytes, peripheral leucocytes, and urine. The activity of hexosaminidase A is appreciably decreased in dead cells and hence in uncultured amniotic fluid cells. Hence reliable identification in utero of the three genotypes may be achieved only by examining the cultured living amniotic cells.     

羊水菌群的研究进展

传统观念认为胎儿在宫内发育的过程是无菌的。随着研究方法的快速发展,针对于微生物的研究方法从传统的培养到现代分子生物学检测的进步,研究者已经认识到胎盘、羊水中具有微生物的存在。目前的研究尚不能明确胎儿宫内胎盘、羊水的菌群来源及菌群转移的具体途径,但已有的研究提示羊水菌群最可能来源为母亲肠道、生殖道以及口腔。本文综述了研究者对羊水菌群认识的转变、羊水菌群的来源以及羊水菌群与早产的相关性。     

Labour: when to worry.

To ensure an optimum result in pregnancy it is essential that the physician be alert in the antenatal period to recognize those women and their babies who are at risk during labour. Premature labour, with its attendant risk of respiratory distress syndrome in the newborn, continues to be an important factor in perinatal morbidity and mortality. Early recognition of predisposing factors and the judicious use of myometrial inhibiting agents have helped to reduce the incidence of fetal prematurity in these cases. A long interval between rupture of the membranes and delivery continues to be a danger to both mother and fetus. Delivery is recommended when gestation is beyond 36 weeks or when there are signs of incipient infection, and once labour has begun antibiotics should be used prophylactically. Failure of labour to progress should be recognized and managed aggressively in its early stages. Amniotomy and oxytocin infusion have reduced considerably the incidence of prolonged labour and its risks to both mother and fetus. The role of intrapartum monitoring of the fetal heart rate, measurement of the pH in the fetus''s scalp blood and assessment of amniotic fluid is discussed, as is the monitoring of maternal well-being.     

Amniotic fluid induces rapid epithelialization in the experimentally ruptured fetal mouse palate--implications for fetal wound healing

Cleft of the secondary palate is one of the most common congenital birth defects in humans. The primary cause of cleft palate formation is a failure of fusion of bilateral palatal shelves, but rupture of the once fused palate has also been suggested to take place in utero. The possibility of post-fusion rupture of the palate in humans has hardly been accepted, mainly because in all the cleft palate cases, the cleft palatal edge is always covered with intact epithelium. To verify whether the intrauterine environment of the fetus plays roles in wound healing when the once fused palate is torn apart, we artificially tore apart fetal mouse palates after fusion and cultivated them in culture medium with or without mouse or human amniotic fluid. We thereby found that the wounded palatal edge became completely covered with flattened epithelium after 36 hours in culture with amniotic fluid, but not in culture without amniotic fluid. Using histological and scanning electron microscopic analyses of the healing process, it was revealed that the epithelium covering the wound was almost exclusively derived from the adjacent nasal epithelium, but not from the oral epithelium. Such actions of amniotic fluid on the fetal wound were never simulated by exogenous epidermal growth factor (EGF), albumin, or both. In addition, the rapid epithelialization induced by amniotic fluid was not prevented by either PD168393 (an inhibitor of the EGF receptor-specific tyrosine kinase) or SB431542 (a specific inhibitor of TGFbeta receptor type I/ALK5). The present study provides new insights into the unique biological actions of amniotic fluid in the repair of injured fetal palate.