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PubMed1988

The effect of human amniotic fluid on the isolated perfused rat heart.

To test the hypothesis that amniotic fluid directly affects cardiac function, isolated rat hearts were perfused with varying concentrations of centrifuged and filtered human amniotic fluid. The most consistent change seen was a dose-dependent decrease in coronary flow rate. With 10% concentrations, a wide spectrum of changes was seen in both a positive and a negative direction for left ventricular pressure and change in pressure with respect to time, which were closely correlated with the degree of decrease in coronary flow rate. If amniotic fluid has a direct role in depressing cardiac function in amniotic fluid embolism, it may act by decreasing coronary flow rather than by directly suppressing myocardial activity.

Amniotic Fluid↗
PubMed1989

Mouse embryos cultured in amniotic fluid.

One thousand mouse embryos were collected over a period of 6 weeks and randomly assigned to either amniotic fluid aspirated during routine amniocentesis from normal 16 weeks pregnant patients or Earle's medium. The embryos were cultured for 72 hours at 37 degrees C in 5% carbon dioxide in air. Osmolarity, pH, partial arterial carbon dioxide pressure and HCO3- were checked before culture and again at the end of culture. Embryos were assessed according to the stage of development, namely degenerate embryos, morulae and blastocysts. The blastocysts were further divided according to their stage of development. There was a significant improvement in blastulation rate to fully expanded blastocysts in the embryos cultured in the amniotic fluid. The amniotic fluid was fairly variable in composition, pH and osmolarity, whereas the Earle's medium was very uniform in composition between trials. It was concluded that amniotic fluid drawn at 16 weeks from normal women is a good culture medium for mice embryos.

Amniotic Fluid↗
PubMed1987

Protein analysis in amniotic fluid and fetal urine for the assessment of fetal renal function and dysfunction.

Micromolecular proteins (molecular weight less than 68 kD) in amniotic fluid are assumed to be derived largely from fetal urinary excretion and therefore may reflect fetal kidney function and maturation. Microprotein concentrations in amniotic fluid, neonatal urine and urine of fetuses with bilateral urinary tract dilation were analyzed using microgradient gel electrophoresis to separate proteins according to their molecular size. Alpha-1-microglobulin and beta 2-microglobulin were assayed as singular micromolecular marker proteins. Microproteins in amniotic fluid decreased progressively with advancing gestation during the 3rd trimester. Micromolecular protein concentrations in the first postnatal urine of healthy infants born prematurely or at term were similar to those in amniotic fluid of corresponding fetal age and yielded an identical developmental pattern. A strong correlation existed between the microprotein concentrations in amniotic fluid and fetal urine. It is concluded that fetal urinary production is the main determinant for the microprotein content of amniotic fluid and that a major fetal pathway exists for the intrauterine metabolism of these proteins. The 3rd trimester decrease in amniotic fluid seems to be dependent on the increasing reabsorption capacity of proximal tubular cells representing morphological and functional kidney maturation. The exact diagnostic value of microprotein analysis for the assessment of disturbed fetal kidney function has still to be defined by further investigation.

Alpha-Globulins↗
PubMed1989

Ontogeny of CA 125 antigen in pregnancy: immunoradiometric determination in amniotic fluid and immunohistochemical localization in fetal membranes.

CA 125 antigen was measured in amniotic fluid, maternal blood, cord blood, and fetal urine by a commercially available immunoradiometric assay kit. The amniotic fluid was obtained from 99 normal pregnancies at various gestational ages. The mean antigen levels were 29,676, 3350, and 1680 U/ml in amniotic fluid of the first, second, and third trimesters, respectively. In maternal blood, 12.5% of pregnant women in the first trimester of pregnancy showed elevated levels of CA 125 (65 to 100 U/ml). Late in gestation, CA 125 levels in cord blood and fetal urine were always less than 65 U/ml. Immunohistochemical study of CA 125 in fetal membranes, placenta, and decidua showed the presence of antigen only in the amnion. These results suggest that CA 125 is shed into amniotic fluid directly from the amniotic membrane.

Amniotic Fluid↗
PubMed1997

Broad-spectrum bacterial rDNA polymerase chain reaction assay for detecting amniotic fluid infection among women in premature labor.

We amplified bacterial 16S rRNA encoding DNA (rDNA) with the polymerase chain reaction (PCR) to detect amniotic fluid infection in 69 women in premature labor whose membranes were intact. Bacterial rDNA was detected by PCR in samples from 15 (94%) of 16 patients with positive amniotic fluid cultures. Bacteria were detected by PCR in samples from 5 (36%) of 14 patients with negative cultures and elevated interleukin (IL)-6 levels vs. 1 (3%) of 39 patients with negative cultures and IL-6 levels of < or = 2,000 pg/mL (P < .01). The median amniotic fluid cytokine levels and the pregnancy outcomes were similar for patients with positive amniotic fluid cultures and those with negative cultures and positive rDNA PCR assays. The association between amniotic fluid infection and premature labor may be underestimated on the basis of amniotic fluid culture results. The broad-spectrum bacterial 16S rDNA PCR assay may prove useful for diagnosing amniotic fluid infection.

Amniotic Fluid↗
PubMed1988

Mutagenicity testing of amniotic fluid from diabetic women, with special reference to their smoking habits.

Amniotic fluid from 16 diabetic and 78 healthy women at term was tested for capacity to cause mutations in Salmonella typhimurium bacterial tester strain TA98 (Ames test). Diabetes as well as heavy smoking increased the mutagenic activity of amniotic fluid. The difference between groups of diabetics and controls was significant in both nonsmokers and women who had smoked more than 5 cigarettes the last 48 h before delivery. It seems plausible that metabolic disturbances, perhaps enhanced by a lowered oxygenation, in some instances could produce mutagenic compounds. Mutagenic activity in amniotic fluid may be one of the factors underlying the increased incidence of congenital malformations in the offspring of diabetic women. Early mutations could cause such developmental errors in the embryos, and possibly also in future generations by damage to germ cells. Heavy smoking alone also caused an increase in mutagenic activity in term amniotic fluid. Our findings reflected an enhancing effect of smoking in diabetes. A pregnant diabetic woman who smoked would thus further endanger her already jeopardized pregnancy.

Amniotic Fluid↗
PubMed1993

Acute hemodynamic and respiratory effects of amniotic fluid embolism in the pregnant goat model.

OBJECTIVE: Our purpose was to determine the acute-phase central hemodynamic and respiratory effects of raw, filtered, filtered and boiled, and meconium-containing amniotic fluid. STUDY DESIGN: Pregnant goats (Capra hircus) in the last one third of pregnancy were given freshly collected autologous amniotic fluid in a volume of 2.5 ml/kg of body weight. Observations were then made at 10, 30, 60, 120, and 180 minutes after amniotic fluid embolism. Pulmonary artery catheters and femoral artery lung water catheters were placed for specimen and data collection. RESULTS: Marked pressor responses were observed in both the pulmonary and systemic circulations with all amniotic fluid infusions. The pressor response was similar with raw, filtered, and filtered and boiled amniotic fluid. The pressor response seen with amniotic fluid containing meconium was significantly greater than that seen with the other forms. No significant effects were observed on cardiac or respiratory function except in the meconium group, where transient left ventricular dysfunction was accompanied by an acute increase in extravascular lung water and dysoxia. CONCLUSIONS: The Capra hircus model is appropriate for the further study of amniotic fluid embolism. The acute pressor effects are transient and involve both the systemic and pulmonary circulations. Left ventricular dysfunction and dysoxia were observed only with embolism of amniotic fluid containing meconium.

Amniotic Fluid↗
PubMed1994

Amniotic fluid enhances allogeneic cytotoxic T cell responses, whereas it suppresses mitogen-stimulated lymphocyte proliferation.

Mouse amniotic fluid has been shown to suppress T lymphocyte proliferation and suggested to be important in regulating immunity during pregnancy. In allogeneic pregnancy, cytotoxic T cells in pregnant lymphocytes against paternal transplantation antigen are impaired. We examined the effect of amniotic fluid to the alloreactive CTL responses. Although the amniotic fluid suppressed Con A or LPS stimulated lymphocyte proliferation as previously reported, the amniotic fluid taken from syngeneic C57BL/6 pregnant mice or allogeneic C57BL/6 x BALB/c pregnant mice enhanced the anti-H-2d or anti-H-2k CTL responses dose-dependently. We speculate that amniotic fluid contains not only immunosuppressive factors but also immunoenhancing factors which upregulate the allogeneic CTL responses.

Amniotic Fluid↗
PubMed2005

Cell-free foetal DNA in maternal plasma does not appear to be derived from the rich pool of cell-free foetal DNA in amniotic fluid.

BACKGROUND: Large quantities of cell-free foetal DNA have been detected in amniotic fluid, and it has been proposed that this material may contribute to the pool of cell-free foetal DNA in maternal plasma. METHODS: Twelve maternal blood samples were obtained from pregnant women about to undergo an amniocentesis. Cell-free DNA was extracted from the maternal plasma samples and the matched amniotic fluid samples. The amount of cell-free foetal DNA was quantified by real-time PCR assays for the SRY and RHD genes. RESULTS: Amniotic fluid was found to contain vast quantities of cell-free DNA (median concentration = 3,978 copies/ml amniotic fluid). The concentration of cell-free foetal DNA in maternal plasma was much lower (median concentration = 96.6 copies/ml maternal plasma). No significant correlation could, however, be determined between these two pools of cell-free foetal DNA. CONCLUSIONS: Our data confirm that amniotic fluid contains prodigious quantities of cell-free foetal DNA, but as no relationship exists between this material and that in the maternal circulation, it is unlikely that the amnion contributes to the presence of cell-free foetal DNA in maternal plasma.

Amniotic Fluid↗
PubMed1988

Determination of lamellar body size, number density, and concentration by differential light scattering from amniotic fluid: physical significance of A650.

A new method for characterizing amniotic fluid is presented. The difference in optical absorbance between amniotic fluid diluted with distilled water or glycerol is measured. This differential approach is shown to determine the total light scattered by the surfactant-containing lamellar bodies and not to be affected by interfering chromogens. The lamellar body size, number density, and concentration are in turn quantified from the wavelength dependence of the absorbance difference, which is shown to be accurately predicted by light-scattering theory in the domain of "anomalous diffraction." The concentration of the lamellar bodies is demonstrated to be directly related to the absorbance difference at 650 nm. A maturity criterion, based on that generally accepted for the direct measurement of absorbance at 650 nm (that is, A650 greater than or equal to 0.15), is determined for the differential approach. Hence, measurement of the absorbance difference at 650 nm can be used to assess amniotic fluid both for its optical absorbance and its lamellar body concentration.

Algorithms↗
PubMed2000

[Significance of amnioinfusion and amniotic fluid exchange under continuous internal fetal heart rate monitoring for management of fetal distress during labor].

OBJECTIVE: To discuss the significance of amnioinfusion and amniotic fluid exchange under continuous internal fetal heart rate (FHR) monitoring for management of fetal distress during labor. METHODS: 136 cases with frequent variable deceleration (VD) and meconium stained amniotic fluid during labor were divided into two groups: the study group (68 cases) and the control group (68 cases). The former were treated by amnioinfusion and amniotic fluid exchange, while oxygen inhalation, change of body position, and intravenous infusion for the control group. RESULTS: In the study group, VD disappeared or relieved in 62 cases obviously, and the efficacy rate reached 91.2% (62/68). 48 cases with II degree meconium stained amniotic fluid were treated by amniotic fluid exchange, amniotic fluid became clear or turned to I degree stained in 39 cases. In the control group, VD relieved in 20 cases, the efficacy rate was 19.4%, significantly lower than that of the study group (P < 0.01). In the study group, cesarean section rate was 14.7% neonatal asphyxia 7.4% while they were 47.1% and 48.5% in the control group respectively (P < 0.01; P < 0.01). Neonatal pneumonia caused by meconium aspiration occurred in 13 cases, meconium aspiration syndrome (MAS) 8 cases, with 5 newborns died in the control group, while there was no neonatal death in the study group. There was no significant difference on puerperal morbidity between the 2 groups (P > 0.05). CONCLUSIONS: Amnioinfusion and AF exchange during labor are one of the effective treatment methods for fetal distress and prevention for MAS.

Adult↗
PubMed1976

Amniotic fluid surface tension during pregnancy.

A good correlation between the amniotic fluid surface tension and gestational age was found in 51 amniotic fluid samples from normal pregnancies. The samples were obtained between the 20th and 43rd week of gestation. A good relation also exists between amniotic fluid lecithin concentration and fluid surface tension, and between said surface tension and the foam test carried out according to Clements et al. (4).

Amniotic Fluid↗
PubMedDate not supplied

Prenatal cytogenetic diagnosis of the fragile X chromosome: feasibility and speed of in situ clonal method in amniotic fluid cell tissue culture.

We have had experience with over 300 amniotic fluid specimens for prenatal diagnosis for the fragile X chromosome [fra(X)], and the flask method of tissue culture has been routinely utilized requiring extended tissue culture periods of 3-4 weeks. The use of the in situ clonal method of tissue culture for routine prenatal cytogenetic diagnosis of amniotic fluid cells has shortened tissue culture time and resulted in more rapid reporting; however, it has not been widely employed for fra(X) prenatal diagnosis. The simultaneous use of both methods of tissue culture has resulted in the detection of 2 cytogenetically fra(X) positive cases in amniotic fluid, with more rapid reporting and satisfactory expression of the fra(X) with the in situ clonal method. Thus, the use of the in situ clonal method of tissue culture for fra(X) prenatal diagnosis in amniotic fluid cells is feasible, faster and can serve as a more rapid cytogenetic adjunct to the newer DNA testing methods.

Amniotic Fluid↗
PubMed1996

Low molecular mass proteins and urinary enzymes in amniotic fluid of healthy pregnant women at progressive stages of gestation.

OBJECTIVES: Amniotic fluid alpha1-microglobulin (alpha1-m) and beta2-microglobulin (beta2-m) levels, as well as N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities, were measured in the course of uncomplicated pregnancies to assess their variations as gestation progresses. DESIGN AND METHODS: Samples were obtained from 141 healthy pregnant women divided into three groups on the basis of gestational stage. Quantitative estimation of proteins was performed immunometrically and enzyme activities were determined spectrophotometrically. RESULTS: It was found that, during pregnancy, alpha1-m and beta2-m concentrations as well as AAP activity significantly decrease, although their reduction patterns vary. Controversial results were found for NAG activity: the normalization of values for amniotic fluid creatinine significantly changed the reduction pattern of this enzyme. No statistically significant differences were found between male and female fetuses for amniotic fluid values of the biochemical substances studied. CONCLUSIONS: The behavior observed for alpha1-m, beta2-m, and AAP might be linked to the progressive development and maturation of fetal renal tubular function. Amniotic fluid total NAG activity seems not to depend only on fetal urinary excretion.

Acetylglucosaminidase↗
PubMed1980

Characterization of triacylglycerol lipase activity in human amniotic fluid.

A radiochemical assay was used to measure the triacylglycerol lipase activity found in normal human amniotic fluid at term. Enzyme activity was characterized in a partially purified extract of amniotic fluid and was found to be optimal at pH 8.0 +/- 0.2 in the presence of 5mM sodium taurocholate, with the use of emulsified tri-[3H]oleoyl glycerol as the substrate. The assay described made it possible to determine the lipase activity in as little as 25 microliters of a 12,000 x g supernatent of whole amniotic fluid as the source of enzyme. The lipase appeared to be distinct from another triacylglycerol lipase measurable in fetal membranes. In turn, it was shown that the amniotic fluid enzyme exhibited several catalytic properties which resembled those of pancreatic lipase. i.e., its substrate specificity, the bimodal effect of bile salt, and the influence of authentic pancreatic colipase on the catalytic process. The results suggest that the assay of triacylglycerol lipase activity may be clinically useful in the detection of enzyme abnormalities in human amniotic fluid.

Amniotic Fluid↗
PubMed1990

Biochemical and immunochemical identification of the fetal polypeptides of human amniotic fluid during the second trimester of pregnancy.

1. Human amniotic fluid contains a complex mixture of proteins, of which only the minority are of fetal origin. We have identified the fetal polypeptides of second trimester amniotic fluid samples by two different methods. 2. The first method was the side by side comparison of silver-stained two-dimensional polyacrylamide gels of amniotic fluid polypeptides with pregnant female plasma polypeptides, after passage of both through a Blue Sepharose affinity column to remove albumin. The second method was the identification of the fetal polypeptides in two-dimensional Western blots with an antiserum made specific for fetal proteins. 3. Using these techniques we have identified 13 major fetal polypeptide fractions with apparent molecular weights of 220, 200, 82, 70, 59, 52, 50, 36, 30, 25, 20, 18 and 11 kDa. Five of these polypeptides, with molecular weights of 82, 59, 50, 20 and 18 kDa, have not previously identified. The identification of these fetal components provides a reference base for molecular studies of normal and pathological fetal development.

Amniotic Fluid↗
PubMed1990

Maternal dehydration: impact on ovine amniotic fluid volume and composition.

Maternal dehydration consistent with mild water deprivation or moderate exercise results in maternal and fetal plasma hyperosmolality and increased plasma arginine vasopressin (AVP). Previous studies have demonstrated a reduction in fetal urine and lung fluid production in response to maternal dehydration or exogenous fetal AVP. As fetal urine and perhaps lung liquid combine to produce amniotic fluid, maternal dehydration may affect the amniotic fluid volume and/or composition. In the present study, six chronically-prepared pregnant ewes with singleton fetuses (128 +/- 1 day) were water deprived for 54 h to determine the effect on amniotic fluid. Maternal plasma osmolality (306.5 +/- 0.9 to 315.6 +/- 1.9 mOsm/kg) and AVP (1.9 +/- 0.2 to 22.2 +/- 3.2 pg/ml) significantly increased during dehydration. Similarly, fetal plasma osmolality (300.0 +/- 0.9 to 312.7 +/- 1.7 mOsm/kg) and AVP (1.4 +/- 0.1 to 10.4 +/- 2.4 pg/ml) increased in parallel to maternal values. Amniotic fluid osmolality (276.8 +/- 5.7 to 311.6 +/- 6.5 mOsm/kg) and sodium (139.8 +/- 4.8 to 154.0 +/- 5.4 mEq/l) and potassium (9.1 +/- 1.3 to 13.9 +/- 2.4 mEq/l) concentrations increased while a significant (35%) reduction in amniotic fluid volume occurred (871 +/- 106 to 520 +/- 107 ml). These results indicate that maternal dehydration may have marked effects on maternal-fetal-amniotic fluid dynamics, possibly contributing to the development of oligohydramnios.

Amniotic Fluid↗
PubMed1985

Theoretical effects of amniotic fluid volume changes on surfactant concentration measurements.

A baseline model for consideration of the theoretical effects of amniotic fluid volume changes on surfactant concentration measurements has been constructed. The baseline data include: a polynomial equation that best fits experimental data comparing amniotic fluid lecithin concentration measurements to gestational age, inflow of 0.450 L of surfactant-poor fluid into the amniotic fluid per day, outflow of 0.450 L of surfactant-rich fluid per day, and volume of 1.0 L of amniotic fluid between 30 to 31 and 38 to 39 weeks' gestation. With this model the incremental amounts of lecithin necessary to achieve the concentration levels derived from the polynomial equation have been calculated. The quantity of lecithin needed was calculated at intervals of 0.1 day for 56 days. Polyhydramnios and oligohydramnios were then allowed to develop hypothetically by modifying the inflow or outflow of fluid while keeping the quantity of lecithin added exactly the same as was determined from the baseline data. Chronic polyhydramnios or oligohydramnios had minimal effects on the concentration measurements. The effects of acute polyhydramnios (or oligohydramnios) were greater when the change in volume was due to an increased (or decreased) volume of inflow as compared to a decreased (or increased) volume of outflow.

Acute Disease↗