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PubMed1975

Amniotic fluid alphafetoprotein measurements in the early prenatal diagnosis of central nervous system disorders.

Amniotic fluid alphafetoprotein (AFP) has been measured in 520 pregnancies between 8 and 24 weeks of gestation. The normal range of values has been defined for fortnightly periods between these limits. Grossly elevated AFP concentrations were found in four pregnancies leading to spina bifida and nine pregnancies leading to anencephaly. Slightly elevated AFP concentrations were found in one twin pregnancy and two pregnancies affected by rhesus isoimmunisation. Normal AFP values were observed in 36 amniotic fluids from pregnancies where the outcome was rhesus isoimmunisation, an inborn error of metabolism, a cytogenetic disorder or a birth defect unrelated to the central nervous system. The reliability of amniotic fluid AFP in the early prenatal diagnosis of spina bifida and anencephaly and the possibility of performing assays on samples sent by post from any part of the world are emphasized.

Abortion, Spontaneous↗
PubMedDate not supplied

Testosterone levels in midtrimester maternal and fetal plasma and amniotic fluid.

Testosterone was measured in maternal plasma (58 samples), amniotic fluid (71 samples) and fetal plasma (55 samples) in 79 patients between 15 and 23 weeks' gestation. Maternal plasma testosterone levels were unrelated to fetal sex. Amniotic fluid testosterone was significantly higher in male than female fetuses but did not reliably predict fetal sex. A correct diagnosis of fetal sex was made by testosterone assay of pure fetal plasma in 39 out of 40 males and in 15 out of 15 females using 1.70 nmol/l as the cut-off value. This investigation is not the method of choice for routine fetal sexing but may be of value in fetuses suspected of having certain endocrine disorders.

Amniotic Fluid↗
PubMed1978

The measurement of phosphatidate phosphohydrolase in human amniotic fluid.

Phosphatidate phosphohydrolase (EC 3.1.3.4) activity can be found in late gestational human amniotic fluid and is thought to originate in type II alveolar cells of the fetal lungs where it plays an important role in lung surfactant synthesis. In the present study, phosphatidate phosphohydrolase activity was detected and characterized in a 105 000 X g pellet of amniotic fluid using either [32P]phosphatidate or a water-soluble analog, 1-O-hexadecyl-rac-[2-(3)H]glycerol 3-phosphate as substrate. With either substrate, enzyme activity was optimal at pH 6.0. The soluble analog was hydrolyzed with a Km value of 163 micrometer and a V of 30 nmole/min per mg of protein, and offered several advantages over phosphatidate as a substrate for assaying phosphatidate phosphohydrolase in amniotic fluid. Using the synthetic analog, phosphatidate phosphohydrolase activity was measured in the 700 X g supernatant fraction of 30 human amniocentesis samples and compared with another index of fetal lung maturity, the phosphatidylcholine/sphingomyelin ratio. The results suggest that the new phosphohydrolase assay may be clinically useful in the assessment of fetal lung development.

Amniotic Fluid↗
PubMedDate not supplied

Corticosteroids and progesterone in amniotic fluid and maternal plasma of the rat and their relation to parturition.

The concentration of total and free corticosteroids, total progesterone and corticosteroid binding activity were determined in the amniotic fluid of rats on each of the 5 days before birth. The levels of total and free corticosteroids were low 4 days before birth but increased to peak levels (15.8 +/- 2.9 micrograms/100 ml and 6.4 +/- 1.1 micrograms/100 ml, respectively) 1 day prior to birth. These increases in the concentration of corticosteroids in amniotic fluid coincided with changes in the level of free corticosteroids but not total corticosteroids in foetal plasma. The level of corticosteroid binding activity increased from 0.9 +/- 0.15 micrograms corticosterone bound/100 ml 4 days before birth to peak at 13.3 +/- 0.8 micrograms corticosterone bound/100 ml 2 days prior to birth. Preliminary investigations suggest that the binding activity is due to a corticosteroid binding globulin-like protein. The concentration of progesterone in amniotic fluid was low compared to that found in maternal plasma and they were not significantly correlated. The concentration of total and free corticosteroids in maternal plasma did not change significantly (P > 0.05) during the 4 days preceding birth and did not correlate with levels of total and free corticosteroids in amniotic fluid. However, there was a significant negative correlation (P < 0.01) between the declining level of progesterone in maternal plasma and increasing levels of total and free corticosteroids in amniotic fluid.

Adrenal Cortex Hormones↗
PubMed1989

Esterase activity in second- and third-trimester amniotic fluid: an indicator of chorioamnionitis.

Accurate and rapid diagnosis of chorioamnionitis poses a major diagnostic dilemma. We previously reported that leukocyte esterase activity in amniotic fluid, as measured by dipstick assay, could be used as an aid in the diagnosis of chorioamnionitis. This study examines the effectiveness of an in vitro spectrophotometric assay of esterase activity in amniotic fluid. We define baseline levels of esterase activity in uninfected amniotic fluid and demonstrate a quantitative increase when infection is present. Fifty-seven amniotic fluid samples obtained at second- and third-trimester amniocenteses were divided into three parts, one for culture and two for a comparison of esterase activities by the dipstick and spectrophotometric methods. In this study, the spectrophotometric assay, because of its higher specificity and sensitivity in the determination of elevated esterase activity, was shown to be more reliable for predicting chorioamnionitis than either the dipstick or culture method.

Amniocentesis↗
PubMed1975

Phospholipids and creatinine in amniotic fluid in relation to gestational age.

185 samples of amniotic fluid were obtained from 174 healthy women with uncomplicated pregnancies in the 15th-43rd week of pregnancy by abdominal amniocentesis or by puncture of the amniotic sac via an amnioscope. The concentrations of creatinine (183 cases), phospholipid phosphorus and the ratio of lecithin/sphingomyelin (L/S-ratio, 130 cases) were determined. The treatment of the amniotic fluid samples (centrifugation, filtration and lipid extraction) and the methods for the determination of L/S-ratio were examined and the accuracy and limitations of the latter method were defined and discussed. The relative amounts of lecithin and sphingomyelin as well as the L/S-ratio and creatinine concentration were closely correlated to gestational age. A L/S-ratio of greater than or equal to 2.25 indicated all women to be greater than or equal to 34th week of pregnancy; 64% of them had reached the 38th week. A creatinine concentration of greater than or equal to 1.8 mg% corresponded to X greater than or equal to 35th week or pregnancy, while 75% of the women had reached at least the 38th week. With a L/S-ratio greater than or equal to 2.25 and a creatinine concentration greater or equal to 1.8 mg% of all women were greater than or equal the 36th week. 71% of the women greater or equal the 38th week fulfilled these critiera. A combination of the two parameters seems to be of a great value in discrimination between gestational ages less than the 36th week and greater than or equal to the 38th week.

Amniocentesis↗
PubMed1977

Amniotic fluid antibacterial mechanisms: newer concepts.

In this review the factors present in human amniotic fluid that may function to inhibit bacterial growth have been examined. It appears that several potential antibacterial systems are present. Lysozyme and B-lysin may significantly contribute to the killing of gram-positive bacteria. Whether or not the remaining antibacterial systems function to inhibit gram-positive organisms remains to be determined. The phosphate-sensitive bacterial inhibitor recently described in our laboratory may represent the primary defense mechanism against gram-negative bacteria in amniotic fluid. Studies are warranted to ascertain whether this antibacterial system also inhibits gram-positive bacteria. The phosphate-sensitive bacterial inhibitor is quite different from other bacterial inhibitors in at least three respects. The system is very sensitive to the ubiquitous phosphate anion. The reason for this sensitivity is unknown and is difficult to explain phylogenetically, since phosphates are present virtually everywhere. To our knowledge this is the first antibacterial system of human origin which has been shown to require a metal cation as an integral part of the bactericidal effect. The peptide component of the phosphate-sensitive bacterial inhibitor is also unique in that it is of the molecular size of antibiotics or hormones. Additionally, the peptide does not appear to contain any unusual amino acids to explain its antibacterial activity. The mechanism of bacterial destruction of the phosphate-sensitive bacterial inhibitor, and its relation to the other antibacterial systems in amniotic fluid, remain to be elucidated.

Amniotic Fluid↗
PubMed1983

Concentrations of prolactin in the plasma of fetal sheep and in amniotic fluid in late gestation and during dexamethasone-induced parturition.

The concentration of prolactin in samples of fetal plasma and amniotic fluid collected from sheep with indwelling catheters has been measured by radioimmunoassay. There was considerable variation between animals in the concentration of prolactin in fetal plasma which ranged from less than 2 micrograms/l to greater than 50 micrograms/l. In five out of eight fetuses which were sampled at intervals throughout the last 30 days of pregnancy, there was an increase in the concentration of prolactin in the plasma before parturition. The concentration of prolactin in amniotic fluid was consistently low (approximately 1 microgram/l). Induction of premature parturition by intrafetal infusion of dexamethasone was accompanied by an increase in the concentration of prolactin in only one of three fetuses infused. These results indicated that prolactin is present in fetal plasma but that an increase in prolactin in fetal plasma before the onset of parturition does not always occur. The low concentration of prolactin in amniotic fluid contrasts with the high concentrations of this hormone found in the amniotic fluid of the primate.

Amniotic Fluid↗
PubMed1990

Effects of heavy metals on alpha-fetoprotein in maternal sera and amniotic fluid of pregnant mice.

This report describes the effects of low levels of copper, nickel and lead salts on the concentrations of alpha-fetoprotein (AFP) in the sera and amniotic fluid of pregnant Nylar mice. During the early and mid-gestation (9-17 days), pregnant mice were injected intraperitoneally twice with heavy-metal salt solutions and were autopsied two days following the second injection. Maternal sera and amniotic fluid (AF) were collected and AFP levels were quantified by radial immunodiffusion. Metal levels determined by X-ray fluorescence spectroscopy in individual samples confirmed the presence of trace metals in the fetus. Low doses of nickel and copper were associated with elevated AFP levels in amniotic fluid in 15-17 day pregnant animals, while maternal serum AFP levels mostly remained unchanged. Decreased concentrations of maternal serum AFP occurred with increased doses of copper and lead in contrast to elevated concentrations of AFP in amniotic fluid. Furthermore, there was an increase in fetal wastage when higher doses of copper and lead were administered. A reduction of secondary litter size (F1 generation) with low dosage levels of lead was also observed. These results imply that the fetal-maternal transfer of AFP may either be impaired or reflect increased leakage or decreased placental permeability in the presence of sublethal doses of copper and lead. These findings suggest that the parallel measurements of AFP concentrations in sera and amniotic fluid might be employed for assessment of embryo- and fetotoxicity when heavy metal intake is suspected during pregnancy.

Amniotic Fluid↗
PubMed1999

Amniotic fluid nitric oxide metabolites, cyclic guanosine 3',5' monophosphate and dimethylarginine in alloimmunized pregnancies.

OBJECTIVE: To determine the relationship between gestational age or the Liley index (the severity of fetal hemolysis) and the amniotic fluid total nitrite (NOx), cyclic guanosine 3',5 'monophosphate (cGMP) and dimethylarginine (DMA) concentrations. We hypothesized that the concentrations of these components change because of fetal growth or adaptation to fetal anemia. STUDY DESIGN: Amniotic fluids (n=64) were obtained between 23 and 37 weeks from fifty-three patients at risk for alloimmunization. Amniotic fluids from the pregnancies with a Liley index=1 were considered as controls (n=17). Creatinine (C, microMol) was determined with the Jaffé reagent, nitrite (NOx, microMol) with the Griess reagent, cGMP (nMol) by an enzyme immunoassay and DMA (microMol) after HPLC. Multiple regression analysis was used for separating the effects of growth and the estimated degree of anemia. RESULTS: The concentration of NOx, cGMP and DMA was not related to the Liley index or whether or not the fetuses needed blood transfusions. The concentrations of creatinine (C), NOx and cGMP increased during pregnancy (in weeks;W) (C=-69.2+6.28W; r2=0.532; P<0.0001, NOx=-17.6+1.29W; r2=0.106; P=0.01, cGMP=-20.9+1.05W; r2=0.414; P<0.0001). The DMA concentration (3.8+/-0.8(SD) and the NOx/creatinine ratio (181+/-110 mM/M) did not change with gestational age. The cGMP/creatinine ratios (microM/M) increased (cGMP/C=-41.8+4.31W; r2=0.134; P=0.007) whereas the DMA/creatinine ratio (mM/M) declined during pregnancy (DMA/C=73.1-1.34W; r2=0.278; P=0.0002). Consequently, the NOx/DMA and cGMP/DMA ratios increased (NOx/DMA=-6.96+0.43W; r2=0.105; P=0.02, cGMP/DMA=-5.9+0.29W; r2=0.391; P<0.0001). CONCLUSIONS: The concentrations in amniotic fluid of cGMP and NOX, but not of DMA increase during gestation. The cGMP/creatinine ratio increases also whereas that of DMA decreases. The changes in products of the NO-cGMP pathway are independent of mild to moderate fetal hemolysis and may result from fetal growth as well as from reduced inhibition of NO synthase by DMA. Gestational age related effects should be taken into account when analyzing nitric oxide metabolites in amniotic fluids.

Amniocentesis↗
PubMed1982

Cultivated cells from mid-trimester amniotic fluids: IV. Cell type indentification via one and two-dimensional electrophoresis of clonal whole cell homogenates.

Clones of cultivated amniotic fluid cells that have distinct morphologic and growth characteristics (F, AF and E-type) were examined by one-dimensional SDS polyacrylamide gel electrophoresis (SDS-PAGE) and by two-dimensional electrophoresis employing isoelectric focusing and SDS-PAGE (IEF-PAGE). No qualitative differences in band pattern were observed in SDS-PAGE between the various amniotic fluid cell types, but consistent quantitative differences in the ratios of four bands of presumed filamentous proteins provided good distinction between amniotic fluid cells and postnatal skin fibroblast-like cells. By adding separation on the basis of electrical charge to that of molecular size (IEF-PAGE), we observed reproducible qualitative differences in the protein spot patterns between F and both AF and E-type amniotic fluid cells. At least eight discrete proteins appear not be synthesized by prenatal F-type cells in comparison with their isogenic AF and E counterparts under identical culture conditions. The two-dimensional electrophoretic patterns thus confirm that F and AF amniotic cells, in spite of their morphologic and growth kinetic similarities, are developmentally distinct cell types that retain their differentiated states in culture.

Amniotic Fluid↗
PubMed1999

Urinary trypsin inhibitor levels in amniotic fluid of normal human pregnancy: decreased levels observed at parturition.

OBJECTIVE: Urinary trypsin inhibitor, a light chain of inter-alpha-trypsin inhibitor, is reported to inhibit uterine contractility during pregnancy. The objective was to measure amniotic fluid urinary trypsin inhibitor levels in women throughout pregnancy. STUDY DESIGN: We determined levels of urinary trypsin inhibitor in human amniotic fluid (n = 40) by means of Western blot analysis. For quantification, computerized scanning and densitometry were used. Results were analyzed for statistical significance with the Mann-Whitney U test. RESULTS: During pregnancy, mean amniotic fluid urinary trypsin inhibitor levels (+/-SD) were 1.5 +/- 0.22, 1. 2 +/- 0.18, and 0.58 +/- 0.24 micromol/L at 15 to 22 (n = 10), 30 to 35 (n = 5), and 37 to 40 (n = 10) weeks' gestation, respectively. There was a significant negative correlation of urinary trypsin inhibitor level with gestational age. A significant difference was observed in amniotic fluid urinary trypsin inhibitor levels before and after (0.10 +/- 0.03 micromol/L; n = 15) the onset of labor. CONCLUSION: Amniotic fluid urinary trypsin inhibitor levels decrease significantly at term. These results support the hypothesis that parturition may occur through the down-regulation of urinary trypsin inhibitor, which may decrease uterine contractility and maintain the uterus in a state of quiescence during pregnancy.

Amniotic Fluid↗
PubMed1992

Pregnancy-associated major basic protein in amniotic fluid.

The pregnancy-associated major basic protein, a protein elevated in the sera of all pregnant women, is virtually identical to the eosinophil granule major basic protein. To determine whether pregnancy-associated major basic protein is present in amniotic fluid, we examined samples from both early and late gestation by a double antibody radioimmunoassay. A total of 112 amniotic fluids were tested and all but three contained levels of pregnancy-associated major basic protein greater than 400 ng/ml. Amniotic fluid pregnancy-associated major basic protein antigenic activity was immunochemically identical to that of the eosinophil granule major basic protein and also had identical physicochemical properties such as heat stability and the need for reduction and alkylation. Although the majority of amniotic fluid samples (90 of 112) were obtained from healthy women with normal gestations, the remaining 21 amniotic fluid samples were from women with Rh sensitization and from one gestation complicated by intrauterine growth retardation.

Amniotic Fluid↗
PubMed1974

Assessment of fetal lung maturity by estimation of amniotic fluid palmitic acid.

The measurement of palmitic acid in amniotic fluid has been shown to be a rapid means of assessing the lecithin concentration. The level of palmitic acid increases quickly when the fetal lung matures at about 35 weeks' gestation, and the level in amniotic fluid obtained 24 hours or less before delivery clearly distinguishes which infants are likely to develop respiratory distress syndrome and which are mature.

Amniotic Fluid↗
PubMed1977

The relationship of amniotic fluid insulin levels and the lecithin-sphingomyelin ratio.

Amniotic fluid insulin levels and the lecithin-sphingomyelin ratio were determined in 62 samples of 33 insulin-dependent diabetic patients from the 29th to the 44th week of gestation inclusive and in 42 samples of 38 gestational diabetic patients from the 35th to the 43rd week of gestation inclusive. (Gestational age was measured by ultrasonography.) The level of insulin in the amniotic fluid did not appear to affect the lecithin-sphingomyelin ratio.

Amniotic Fluid↗
PubMed1987

Total phospholipids in lung and amniotic fluid of chick in determining lung maturity.

The total phospholipid (TPL) concentration in lung and amniotic fluid of chick increases with the advancement of incubation period. A positive correlation (r = 0.77) exists between the lung and amniotic fluid phospholipids. Highest value of TPL was observed at the end of incubation period. Interestingly, in few samples of both lung and amniotic fluid, low concentrations of TPL were also observed.

Amniotic Fluid↗
PubMed2004

Amniotic fluid and cord plasma erythropoietin levels in pregnancies complicated by preeclampsia, pregnancy-induced hypertension and chronic hypertension.

AIMS: The purpose of the present study was to compare fetal and neonatal outcomes with amniotic fluid erythropoietin (EPO) levels obtained in the antepartum period in pregnancies complicated by preeclampsia, pregnancy-induced hypertension or chronic hypertension. METHODS: Erythropoietin concentrations were measured in amniotic fluid within 2 days before delivery and in cord blood at birth in 75 hypertensive women and in 23 healthy controls delivered by cesarean section before labor contractions. Erythropoietin levels did not influence clinical decisions. RESULTS: Amniotic fluid erythropoietin levels correlated highly significantly with cord plasma EPO levels and were significantly higher in pregnancies complicated by hypertension than in control pregnancies. Umbilical arterial pH, acid-base and blood gas values at birth were not different from controls. Both cord plasma and amniotic fluid erythropoietin levels correlated with cord blood pH, acid-base and blood gas values at birth in the study group. Newborn infants admitted to the newborn intensive care unit had significantly higher fetal erythropoietin levels and were more acidotic, hypoxemic and hypoglycemic than infants admitted to the normal care nursery. CONCLUSIONS: Our findings suggest that elevated amniotic fluid erythropoietin levels are markers of chronic or subchronic fetal hypoxia and are associated with neonatal morbidity in pregnancies complicated by hypertension.

Adult↗
PubMed1990

Changes in amniotic fluid concentrations of prostaglandins E2 and F2 alpha in women with preterm labor.

There is a paucity of data regarding the concentration of prostaglandins (PGs) in the amniotic fluid of women with preterm labor. The purpose of this study was to determine if preterm labor is associated with changes in amniotic fluid concentration of prostaglandins E2 and F2 alpha. Amniotic fluid was retrieved by transabdominal amniocentesis from women with preterm labor and intact membranes. Patients were classified into three groups according to the response to tocolysis and the presence or absence of intra-amniotic infection. PGE2 and PGF2 alpha were measured using specific and sensitive RIA kits. Amniotic fluid concentrations of PGE2 and PGF2 alpha were significantly higher in women with preterm labor and intra-amniotic infection than in women without infection, regardless of the response to tocolysis. These data suggest that both PGs are involved in the mechanism of preterm labor and may have prognostic value.

Amniotic Fluid↗