Amniotic fluid beta-2 microglobulin in normal and complicated pregnancies

Beta-2 microglobulin concentrations were measured in amniotic fluid samples obtained from normal pregnant women at various stages of gestation and complicated pregnancies during weeks 32-42 of gestation by the ELISA method. The concentration of beta-2 microglobulin in amniotic fluid increases markedly up to the 20-24th weeks of pregnancy and reaches a peak during the second trimester, occasionally reaching an eightfold value compared to the maternal serum concentration, while at term the values are similar. The decrease of amniotic fluid beta-2 microglobulin level in the third trimester reflects the maturation of foetal renal tubular function and suggests that this test may be of significance in determining foetal age. Our results revealing elevated concentrations of beta-2 microglobulin in patients with diabetes, toxaemia and placental insufficiency may indicate slower renal maturation of the foetus.     

Amniotic fluid and hemodynamic model in monochorionic twin pregnancies and twin-twin transfusion syndrome

We developed a mathematical model of monochorionic twin pregnancies and twin-twin transfusion syndrome (TTTS), combining both fetal fluid dynamics and fetoplacental growth and circulation alterations and assuming that transplacental fluid flow from mother to fetus accounts for normal fetal and amniotic fluid volumes. Ten coupled differential equations, describing fetal total body and amniotic fluid volumes, their osmolalities, and fetal blood colloid osmotic pressure, for both donor and recipient twins, were solved numerically. Amniotic flows are controlled by fetal plasma osmolality and hydrostatic and colloid osmotic pressures. We included varying placental anastomoses and placental sharing of the circulations. Consistent with clinical experience, model predictions are: fetofetal transfusion from unidirectional arteriovenous anastomoses cause oligo-polyhydramnios, a normal size recipient but hypovolemic donor; compensating oppositely directed deep and superficial anastomoses moderate discordant development; and anhydramnios results from mild and severe TTTS, where milder forms may even present earlier in gestation than severe TTTS. Unequal placental circulatory sharing may exacerbate discordant development. In conclusion, our model simulates a wide variety of realistic manifestations of amniotic fluid volume and fetal growth in TTTS related to placental angioarchitecture. The model may allow an assessment of the efficacy of current therapeutic interventions for TTTS.     

Amniotic fluid cathelicidin in PPROM pregnancies: from proteomic discovery to assessing its potential in inflammatory complications diagnosis

Background

Preterm prelabor rupture of membranes (PPROM) complicated by microbial invasion of the amniotic cavity (MIAC) leading to histological chorioamnionitis (HCA) significantly impacts perinatal morbidity. Unfortunately, no well-established tool for identifying PPROM patients threatened by these disorders is available.

Methodology/Principal Findings

We performed an unbiased exploratory analysis of amniotic fluid proteome changes due to MIAC and HCA. From among the top five proteins that showed the most profound and significant change, we sought to confirm results concerning cathelicidin ({"type":"entrez-protein","attrs":{"text":"P49913","term_id":"1706745","term_text":"P49913"}}P49913, CAMP_HUMAN), since an ELISA kit was readily available for this protein. In our exploratory proteomic study, cathelicidin showed a ∼6-fold higher concentration in PPROM patients with confirmed MIAC and HCA. We verified significantly higher levels of cathelicidin in exploratory samples (women without both MIAC and HCA: median 1.4 ng/ml; women with both conditions confirmed: median 3.6 ng/ml; p = 0.0003). A prospective replication cohort was used for independent validation and for assessment of cathelicidin potential to stratify women with MIAC leading to HCA from women in whom at least one of these conditions was ruled out. We confirmed the association of higher amniotic fluid cathelicidin levels with MIAC leading to HCA (the presence of both MIAC and HCA: median 3.1 ng/ml; other women: median 1.4 ng/ml; p<0.0001). A cathelicidin concentration of 4.0 ng/ml was found to be the best cut-off point for identifying PPROM women with both MIAC and HCA. When tested on the validation cohort, a sensitivity of 48%, a specificity of 90%, a likelihood ratio of 5.0, and an area under receiver-operating characteristic curve of 71% were achieved for identification of women with MIAC leading to HCA.

Conclusions

Our multi-stage study suggests cathelicidin as a candidate marker that should be considered for a panel of amniotic fluid proteins permitting identification of PPROM women with MIAC leading to HCA.     

Amniotic fluid 17-hydroxyprogesterone in early pregnancy

The results of measurement of 17-hydroxyprogesterone (17-OH-P) in 125 samples of amniotic fluid (AF) from early amniocenteses are presented. The fetuses from all pregnancies studied were unaffected by congenital adrenal hyperphasia caused by 21-hydroxylase deficiency. The AF 17-OH-P level increases slightly but significantly between the 11th and 15th week of gestation, with a maximum in the 14th week. There is no difference between the values measured in male and female fetuses. The AF 17-OH-P levels from the early gestation were compared with those from the 16th–22nd week of pregnancy (published previously). The overall differences of AF 17-OH-P concentrations when considered in all gestational age groups in the whole period 12–22 weeks were statistically insignificant. Thus, the biochemical prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency and control of its early fetal treatment could be carried out starting from the end of the first trimester in the same way as at the later period of gestation.     

Amniotic fluid arginase in women at term]

Study on 34 cases. A considerable arginasic activity is observed in amniotic fluid in women at the end of pregnancy. This activity is weak, but increased by Mn2+ (about 5 to 8 times). The total amniotic fluid is more active than the surpernatant, the deposit of which has been eliminated. An important part of arginasic activity results from the elements of the deposit (amniotic cells, foetal cells and eventualy erythrocytes in hemorragic amniotic fluid).     

Amniotic fluid 5-hydroxyeicosatetraenoic acid in preterm labor

5-Hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating human uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if preterm labor is associated with changes in the concentration of this metabolite in amniotic acid. Amniotic fluid was obtained by transabdominal amniocentesis from three groups of women with preterm labor: group 1 — women without intraamniotic infection who responded to tocolysis (n = 32); group 2 — women without intraamniotic infection who failed to respond to tocolysis (n = 22); and group 3 — women with intraamniotic infection (n = 14). 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE in women who responded to tocolysis (median = 1412 pg/ml; range: 111–3547) was significantly lower than in women who delivered despite tocolysis (median = 2052 pg/ml; range 136–7774) and women with intraamniotic infection (median = 1876 pg/ml; range: 543–7033) [p < 0.05]). No difference in amniotic fluid concentrations' of 5-HETE were found between women in groups 2 and 3 (p > 0.05).     

Amniotic fluid prostaglandin E2 in preterm labor

These studies were designed to determine amniotic fluid concentrations of prostaglandin E2 (PGE) in women with preterm labor. Amniotic fluid was retrieved by transabdominal amniocentesis from 68 women with preterm labor (less than 37 weeks). Patients were divided into three groups according to the response to tocolysis and the presence or absence of an intraamniotic infection. Amniotic fluid concentrations of PGE2 were significantly greater in women with preterm labor and intraamniotic infection than in women without infection. Patients unresponsive to tocolysis without intraamniotic infection had a significantly greater concentration of PGE2 in amniotic fluid than those responsive to tocolysis.     

Amniotic fluid 5-hydroxyeicosatetraenoic acid in preterm labor

5-Hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating human uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if preterm labor is associated with changes in the concentration of this metabolite in amniotic fluid. Amniotic fluid was obtained by transabdominal amniocentesis from three groups of women with preterm labor: group 1 - women without intraamniotic infection who responded to tocolysis (n = 32); group 2 - women without intraamniotic infection who failed to respond to tocolysis (n = 22); and group 3 - women with intraamniotic infection (n = 14). 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE in women who responded to tocolysis (median = 1412 pg/ml; range: 111-3547) was significantly lower than in women who delivered despite tocolysis (median = 2052 pg/ml; range: 136-7774) and women with intraamniotic infection (median = 1876 pg/ml; range: 543-7033) [p less than 0.05]). No difference in amniotic fluid concentrations' of 5-HETE were found between women in groups 2 and 3 (p greater than 0.05).     

Amniotic fluid prostaglandin D2 in spontaneous and augmented labor

Prostaglandin D2 (PGD2) was quantified in human amniotic fluid obtained from women in various phases of the first stage of spontaneous labor, augmented labor, and induced labor. PGD2 increased significantly only in late labor in the spontaneous and augmented labor groups.     

Amniotic fluid and decidual prolactin during pregnancy in rhesus macaques

In rhesus macaques, the concentration of immunoreactive prolactin in the amniotic fluid remains low during most of the first trimester of pregnancy and then increases abruptly at 60-80 days of gestation. During the second half of pregnancy, large amounts of prolactin accumulate in the amniotic fluid. Much of this amniotic fluid prolactin may originate from the superficial endometrium (decidua). This hypothesis is supported by the increasing amounts of decidual prolactin (dPRL) measured in endometrium obtained at early (50 days), mid-(80 days), and late (greater than or equal to 150 days) gestation. In culture, late pregnancy endometrium released more dPRL than did early pregnancy endometrium. When tissues were cultured in medium without progesterone, the amounts of dPRL measured in the medium declined steadily over 6 days, regardless of the gestational age of the endometrium. dPRL was consistently measured in medium harvested from cultures that received either progesterone or medroxyprogesterone; however, progesterone did not induce an increase in the amounts of dPRL released by cultures prepared from early pregnancy endometrium. This suggests that factors in addition to progesterone may stimulate the increase in dPRL that occurs at midgestation in rhesus macaques.     

Amniotic fluid stem cells to study mTOR signaling in differentiation

The protein kinase mTOR is the central player within a pathway, which is known to be involved in the regulation of e.g., cell size, cell cycle, apoptosis, autophagy, aging and differentiation. mTOR activity responds to many signals, including cellular stress, oxygen, nutrient availability, energy status and growth factors. Deregulation of this enzyme is causatively involved in the molecular development of monogenic human diseases, cancer, obesity, type 2 diabetes or neurodegeneration. Recently, mTOR has also been demonstrated to control stem cell homeostasis. A more detailed investigation of this new mTOR function will be of highest relevance to provide more explicit insights into stem cell regulation in the near future. Different cellular tools, including adult stem cells, embryonic stem cells or induced pluripotent stem cells could be used to investigate the role of mTOR in mammalian stem cell biology. Here we discuss the potential of amniotic fluid stem cells to become a promising cellular model to study the role of signaling cascades in stem cell homeostasis.     

Amniotic fluid embolism and leukotrienes--the role of amniotic fluid surfactant in leukotriene production.

Surfactant rich lipid (lipid) was extracted from cell free 10,000 x g pellets of amniotic fluid. White blood cells (WBC) were isolated from human donors. 36 x 10(7) WBC and 5 g rabbit lung were incubated with pretreated lipid or dipalmitoyl lecithin (lecithin). Leukotrienes (LTs) were identified by high performance liquid chromatography (HPLC) and bioassay, and quantified by radioimmunoassay. Peaks of LTC4 and LTD4 on HPLC and guinea-pig ileum contraction could be identified in lipid and lecithin groups, but not in the control group. LTC4 production by lipid and lecithin groups was significantly higher than that by the control group. An involvement of amniotic fluid surfactant in leukotriene production is suggested.     

Amniotic fluid stem cells to study mTOR signaling in differentiation

The protein kinase mTOR is the central player within a pathway, which is known to be involved in the regulation of e.g., cell size, cell cycle, apoptosis, autophagy, aging and differentiation. mTOR activity responds to many signals, including cellular stress, oxygen, nutrient availability, energy status and growth factors. Deregulation of this enzyme is causatively involved in the molecular development of monogenic human diseases, cancer, obesity, type 2 diabetes or neurodegeneration. Recently, mTOR has also been demonstrated to control stem cell homeostasis. A more detailed investigation of this new mTOR function will be of highest relevance to provide more explicit insights into stem cell regulation in the near future. Different cellular tools, including adult stem cells, embryonic stem cells or induced pluripotent stem cells could be used to investigate the role of mTOR in mammalian stem cell biology. Here we discuss the potential of amniotic fluid stem cells to become a promising cellular model to study the role of signaling cascades in stem cell homeostasis.     

Amniotic fluid levels of tumor necrosis factor-alpha and soluble tumor necrosis factor receptor 1 before and after the onset of labor in normal pregnancies.

Tumor necrosis factor-alpha (TNF-alpha) is present in human placental and uterine cells and promotes the regulation of trophoblast growth and invasion. Tumor necrosis factor receptor 1 (TNF-R1) is a receptor for TNF-alpha, and soluble TNF-R1 (sTNF-R1) is present in amniotic fluid after receptor shedding. We evaluated whether amniotic fluid TNF-alpha and sTNF-R1 levels during labor differed from those before the onset of labor in normal pregnancies. This study enrolled 34 Japanese women experiencing normal pregnancies with single fetuses who had no infection. Of these subjects, 17 went into labor and had subsequent term deliveries (the labor group), and the other 17 underwent cesarean section without labor (the nonlabor group). The average gestational age at entry was 38-39 weeks of gestation. Maternal ages and gestational ages did not differ significantly between the two groups. Amniotic fluid was collected and the TNF-alpha and sTNF-R1 levels were determined by the ELISA method. Each of these levels was compared between the two groups. There was a significant increase in amniotic fluid TNF-alpha levels in the labor group. However, amniotic fluid sTNF-R1 levels did not differ significantly between the two groups. Amniotic fluid TNF-alpha may promote the onset of labor at term and/or term labor contributing to subsequent delivery may induce the production and secretion of TNF-alpha into the amniotic cavity. There was no pregnancy-associated increase in receptor shedding or cell apoptosis at the onset of labor.