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PubMed1993

Spatial and temporal distribution of corticosteroid-binding globulin and its messenger ribonucleic acid in embryonic and fetal mice.

Glucocorticoids influence fetal development, and their actions are regulated by plasma corticosteroid-binding globulin (CBG). Immunohistochemistry and in situ hybridization were, therefore, used to localize CBG and its mRNA in sections of embryonic and fetal mice and their associated placental tissues from day 5 of gestation until term (day 19). In the fetus, CBG mRNA was first detectable in the hepatocytes on day 11 of gestation. The amount of CBG mRNA in these cells increased transiently to a maximum on days 15-16 of gestation and was negligible by day 19. In hepatocytes, CBG immunoreactivity correlated with the distribution and relative abundance of CBG mRNA. The fetal exocrine pancreas also contained CBG mRNA, but this was only present on days 15-16 of gestation, while immunoreactive CBG persisted in these cells until term. Immunoreactive CBG was detected in the tubular cells of the developing fetal kidney as early as day 13, but CBG mRNA was never found in the fetal kidney, suggesting that the protein is probably sequestered from fetal blood directly or via the glomerular filtrate. The placenta contained immunoreactive CBG throughout gestation, even before its detection in fetal tissues, and it was most abundant in the spongiotrophoblasts and the extracellular matrix surrounding fetal and maternal capillaries. However, CBG mRNA was not detected in the placenta at any gestational age. Therefore, CBG present in the placenta is most likely of maternal origin and may influence the activities of steroid hormones that control placental development and/or function. The presence of smaller immunoreactive polypeptides in placental extracts, compared to CBG in corresponding maternal serum samples, suggests that this process may involve an interaction between maternal CBG and placental proteinases. The results presented here suggest that temporal and spatial changes in the localization of CBG and its mRNA in the fetus may influence the effects of steroid hormones on developing tissues.

Amino Acid Sequence↗

PubMed1975

Serum and Placental lactic dehydrogenase and alkaline phosphatase isoenzymes in normal pregnancy and in pre-eclampsia.

LDH isoenzymes and heat-stable alkaline phosphatase were studied in the serum and placental extract of 20 cases of pre-eclampsia and 10 normal pregnancies as a control. The starch-gel electrophoretic serum and placental isoenzymogram showed that LDH4 and LDH5 were the main isoenzymes in the placenta while LDH1 and LDH2 were the main isoenzymes in the serum in pre-eclampsia. The electrophoretic serum protein pattern in pre-eclamlobulins with decreased albumin fraction, while in the placenta, the albumin fraction was increased together with a decrease in the alpha-globulins. The electrophoretic pattern of serum alkaline phosphatase showed a main band of activity at the B-globulin zone in all cases of normal pregnancy and pre-eclampsia. In the placenta, two additional bands were detected.

Alkaline Phosphatase↗

PubMed1995

Plasma and placental calcitonin gene-related peptide in pregnancies complicated by severe preeclampsia.

OBJECTIVE: Our purpose was to determine the concentration of calcitonin gene-related peptide, a potent vasodilator, in maternal plasma, fetal plasma, and placental tissue from pregnancies complicated by severe preeclampsia. STUDY DESIGN: The following groups were studied: severe preeclampsia (group 1, n = 21), normal pregnancies matched for mode of delivery (group 2, n = 21), and nonpregnant women (group 3, n = 17). Maternal venous blood samples were drawn before labor, and fetal venous samples were drawn from the chorionic plate immediately after delivery. Calcitonin gene-related peptide was also quantified in placental tissue samples from 15 patients in group 1 and 15 patients in group 2. Calcitonin gene-related peptide was measured with a sensitive and specific radioimmunoassay. RESULTS: No differences were found between maternal plasma calcitonin gene-related peptide concentrations in groups 1 and 2 (29.8 +/- 4.2 and 30.4 +/- 4.3 pmol/L, respectively). Both had levels similar to those in group 3 (28.5 +/- 5.4 pmol/L). Maternal plasma concentrations in the preeclamptic group were unchanged 3 days post partum (29.1 +/- 3.6 pmol/L). Fetal plasma calcitonin gene-related peptide concentrations were similar in groups 1 and 2 (30.2 +/- 3.9 and 32.2 +/- 8.8 pmol/L, respectively). A significant correlation was found between maternal and fetal calcitonin gene-related peptide concentrations (r = 0.43, p < 0.01). Like plasma levels, calcitonin gene-related peptide levels in the supernatants of placental extracts were not different in preeclamptic and normal pregnancies (108.0 +/- 70.4 and 100.9 +/- 56.1 fmol/gm, respectively). CONCLUSION: On the basis of plasma and placental concentrations, calcitonin gene-related peptide does not seem to play an important role in the pathophysiologic mechanisms of preeclampsia.

Biomarkers↗

PubMed1992

Properties and functions of human placental opioid system.

Human placental villus tissue contains opioid receptors and peptides. Kappa opioid receptors (the only type present in this tissue) were purified with retention of their binding properties. The purified kappa receptor is a glycoprotein with an apparent molecular weight of 63,000. Two opioid receptor mediated functions were identified in trophoblast tissue, namely regulation of acetylcholine and hormonal (human chorionic gonadotrophin and human placental lactogen) release. Placental content of kappa receptors increases with gestational age. Term placental content of kappa receptors correlates with route of delivery (higher in those abdominally obtained). Opioid use and/or abuse during pregnancy affects placental receptor content at delivery, as well as its mediated functions. Opioid peptides identified in placental extracts were beta-endorphin, methionine enkephalin, leucine enkephalin and dynorphins 1-8 and 1-13. Dynorphin 1-8 seem to be the predominant opioid peptide present in placental villus tissue.

Acetylcholine↗

PubMed2001

Differential levels of interleukin 6 in maternal and cord sera and placenta in women with pre-eclampsia.

BACKGROUND: Interleukin 6 (IL-6) is a T helper 2 cytokine with a variety of properties including pro-inflammatory characteristics. It has, therefore, been implicated in the pathophysiology of abnormal pregnancies. OBJECTIVE: To investigate the association between IL-6 and pre-eclampsia by estimating the differential levels of IL-6 in maternal and cord serum and supernatant of homogenized placental tissue. METHODS: 50 primigravidae with pre-eclampsia and 50 matched normotensive primigravidae served as controls. At delivery, maternal and cord blood were collected and the serum extracted. Placental blocks were homogenized and sonicated in RPMI solution and the supernatant collected. The total protein concentration was determined and IL-6 levels assayed with an ELISA technique. RESULTS: Placental IL-6 (170 and 186 pg/mg protein) was threefold that in the maternal (64 and 58 pg/mg protein) and cord serum (63 and 72 pg/mg protein; p < 0.01). There was no significant difference in the mean IL-6 levels in maternal and cord serum or placenta in both pre-eclamptic women and normotensive controls nor in pre-eclamptic patients with babies with intra-uterine growth restriction or in pre-eclamptic patients with babies with an appropriate birth weight and in normotensive controls. CONCLUSION: There are no differences in the maternal and cord sera and placental levels of IL-6 in pre-eclamptic and normotensive women, indicating that IL-6 may not have a role in the pathophysiology of pre-eclampsia.

Adult↗

PubMed1981

Isolation and characterization of Fc gamma receptors from human placenta.

Placental extract was prepared with Tris-HCl buffer pH 7.4 containing EDTA and 2-mercaptoethanol. It agglutinated erythrocytes (E) sensitized with subagglutinating amounts of IgG antibodies from rabbits, guinea pigs and mice, but not E sensitized with IgG from chickens. E or E sensitized with F(ab)2 or IgM antibodies were not agglutinated. The agglutination of EA by the extract was inhibited by human, rabbit and guinea pig IgG, but not by bovine and porcine IgG. Aggregated IgG was more inhibitory than monomeric IgG. IgG3 was the most effective subclass. The extract inhibited the formation of EA rosettes with human mononuclear cells, but did not influence the formation of E or EAC rosettes. The significance of the disulfide bonds and the C gamma 3 and C gamma 2 regions was implied by the finding that the extract neither agglutinated E sensitized with preparations of mildly reduced and alkylated IgG, nor with Facb fragments. These preparations did not inhibit the agglutination. The results strongly indicated that the active component was solubilized placental Fc receptor (FcR). Functionally active FcR was purified by affinity chromatography using aggregated human IgG coupled to Sepharose 4B. SDS-PAGE if the purified FcR under reducing conditions showed one distance band corresponding to approx. 47,000 daltons. The band neither consisted o Ig fragments nor Clq. A rabbit antiserum against the FcR inhibited the agglutination of EA by the extract and stained th FcR-positive areas in placenta.

Chromatography, Affinity↗

PubMed1987

An inhibitor of plasminogen activation from human placenta. Purification and characterization.

Placental extracts contain inhibitors of human urinary urokinase. These extracts form a heterogeneous population of complexes with 125I-urokinase that are recognizable by changes in gel filtration profile and mobility during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Treatment with reducing agents eliminated the size heterogeneity without loss of activity, thereby allowing the placental inhibitor to be purified. Active inhibitor has been isolated in apparently homogeneous form after an eight-step procedure that included salt extraction, ammonium sulfate fractionation, column chromatography on CM-cellulose, DEAE-Sepharose, and hydroxylapatite, chromatofocusing, preparative gel electrophoresis, and hydrophobic chromatography. The purified inhibitor has Mr = 47,000. The inhibitor is relatively specific for plasminogen activators since it does not inhibit the action of plasmin, factor XIIa, plasma kallikrein, or thrombin. The inhibitor forms complexes with 1:1 stoichiometry that block the active sites of urokinase (but not prourokinase) and both one- and two-chain forms of tissue plasminogen activator. The stability of these complexes in sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggest that they are based on covalently bonded structures. Although both types of plasminogen activator are inhibited, the rate of interaction is significantly faster with urokinase, tissue plasminogen activator being inhibited less efficiently. The complexes formed can be dissociated by mild alkali or hydroxylamine, thereby regenerating both enzymes and inhibitor at their original molecular weights. The results suggest that the complexes are stabilized by ester-like bonds; these might involve the hydroxyl of serine at the active site of the proteases and a carboxyl group in the inhibitor.

Amino Acids↗

PubMed1998

Human chorionic gonadotropin beta-core fragment is present in the human placenta.

The presence of hCG beta-core fragment (beta-core) in the human placenta has been controversial. To clarify its presence in the villous tissue, first, we developed an enzyme immunoassay which is highly specific for beta-core. Then, we investigated the presence of beta-core immunoreactivity in the supernatants of placental organ culture and those of primary culture of trophoblasts as well as in the placental extracts at different stages of gestation. The immunoreactivity of beta-core was demonstrated in each sample, and the amount was at least 5% of intact hCG immunoreactivity. Immunohistochemical analysis of the placental tissue showed localization of beta-core immunoreactivity to the syncytiotrophoblast. Western blot analysis of the supernatants of organ culture as well as urine samples of pregnant women showed two major bands with molecular weight of approximately 15000. On the other hand, beta-core immunoreactivity in the pregnant sera ranged from 0.1 to 0.19% of intact hCG immunoreactivity. These results suggest the presence and possible secretion of beta-core fragment in the human placenta, and its immunoreactivity in the serum is likely to be reduced due to its short half life in the maternal blood.

Cell Extracts↗

PubMed1996

Expression of the growth hormone gene in ovine placenta: detection and cellular localization of the protein.

In several species, placenta has been found to express GH-related proteins. In the ovine placenta, such a protein, ovine chorionic somatommamotropin, has been described, but its involvement in the fetal/placental growth process is not clearly established. The aim of this study was to investigate the occurrence of another GH-related peptide in the ovine placenta. Placental extracts (days 30-140 of pregnancy) showed GH immunoreactivity between days 35-70. SDS-PAGE analysis of these extracts indicated that this immunoreactivity corresponded to 22- and 28-kDa proteins. GH-like immunoreactivity was localized on cotyledonary frozen sections in the syncytium and the trophectoderm. Northern blot analysis of placental RNA showed the expression of GH-hybridizing transcripts migrating to the same position as that of GH pituitary messenger RNA (mRNA). Those transcripts were highly expressed between days 40 and 50. Their sequence analysis showed the existence of three GH mRNA (GHP1, GHP2, and GHP3). GHP1 is identical to pituitary GH mRNA and probably codes for the 22-kDa protein. GHP2 and GHP3 encode the same protein, which differs from GHP1 by four amino acids. This study establishes the expression of GH gene and GH-immunoreactive proteins in the ovine placenta.

Animals↗

PubMed1994

A dot-immunobinding assay for the demonstration of soluble Fc gamma receptors.

We have developed a sensitive dot-immunobinding assay to demonstrate and characterize the functional activity of soluble Fc gamma receptors (FcR). Samples containing soluble FcR were immobilized on a nitrocellulose membrane. Immune complexes of horseradish peroxidase and rabbit IgG antibodies to horseradish peroxidase (HRP) were allowed to react with nitrocellulose-bound FcR, and the immune complexes were visualized by HRP developer. The intensity of the grey dots reflected the amount of immune complex bound. Binding of immune complexes to placental extract containing soluble FcR was inhibited completely by IgG and Fc fragments, but not by F(ab')2 fragments, IgA and IgM. The method was used to characterize the subclass specificity of solubilized placental FcR. Human Fc fragments, and intact IgG1 and IgG3 proteins inhibited the binding whereas preparations of F(ab')2, IgG2 and IgG4 did not. In conclusion, the dot-immunobinding assay described is a rapid and simple method for the demonstration and characterization of functionally active soluble FcR.

Antigen-Antibody Complex↗

PubMed1984

Optimal conditions for detection of reverse transcriptase activity in human placentas.

Optimal conditions for detecting reverse transcriptase activity in human placental extracts are described. They vary with the state of the placenta at birth and are influenced by relative amounts of detergent, monovalent cation, and protein in the reaction mixture. Demonstrating activity of the placental enzyme requires detergent, but the enzyme is sensitive to high detergent concentrations. This sensitivity can be be altered by lowering the monovalent cation concentration from 0.154 to 0.034 M and by adding protein to the reaction mixture. The detection of reverse transcriptase in Rauscher murine leukemia virus and baboon endogenous type C virus, but not in the Mason-Pfizer monkey type D virus, shows similar requirements.

Animals↗

PubMed2005

Novel placental expression of 2,3-bisphosphoglycerate mutase.

2,3-Bisphosphoglycerate mutase (2,3-BPGM), an erythroid-expressed enzyme, synthesises 2,3-bisphosphoglycerate (2,3-BPG), the allosteric modulator of haemoglobin. This ligand has a higher affinity for adult haemoglobin than for fetal haemoglobin and differential binding of it facilitates transfer of oxygen between adult and fetal blood by lowering the affinity of adult haemoglobin for oxygen. This paper reports the discovery that 2,3-BPGM is synthesised in non-erythroid cells of the human placenta. Western blot analysis of placental extracts revealed high levels of 2,3-BPGM in the human placenta. Immunohistochemical staining and in situ hybridisation experiments indicated that abundant 2,3-BPGM is present in the syncytiotrophoblast layer of the placental villi at the feto-maternal interface. A cytochemical staining technique showed that the placental 2,3-BPGM is active, indicating that 2,3-BPG is synthesised in the outermost cells of the placenta. These observations demonstrate an unexpected and abundant presence of an enzyme key to oxygen release from adult haemoglobin, at the interface between maternal and fetal circulations.

Bisphosphoglycerate Mutase↗

PubMed1984

Origins and significance of the increased plasma alkaline phosphatase during normal pregnancy and pre-eclampsia.

Total alkaline phosphatase (AP) was measured in maternal plasma, cord plasma and placental extracts in normal and in pre-eclamptic pregnancies. Total plasma AP was significantly elevated during the last two trimesters in normal and pre-eclamptic pregnancies, but contrary to previous reports, both placental and bone AP isoenzymes contributed to the significant elevation of total AP in both types of pregnancy. There was no placental AP isoenzyme in cord plasma but total cord plasma AP was higher in normotensive pregnancies than in pre-eclamptic pregnancies. Total AP concentration in placental tissue was higher in normotensive pregnancies than in pre-eclamptic pregnancies. A correlation was established between placental weights and maternal circulating placental AP.

Adolescent↗

PubMed1999

Recombinant and tissue extract thromboplastins for determination of international normalised ratio in over-anticoagulated patients.

The international normalised ratio (INR)/international sensitivity index (ISI) system is established for calibration of thromboplastins for laboratory monitoring of oral anticoagulant therapy. The calibration procedure employs patients stabilised on oral anticoagulants, and is therefore validated for patients within the therapeutic range. For practical reasons, the system is used for patients at all levels of therapy, including over-anticoagulated patients with particularly low levels of factors II, VII and X. We studied patients within and above the therapeutic range, using a thromboplastin containing recombinant human tissue factor (Innovin) and two tissue extract thromboplastins. In samples with INRs from 2.0 to 4.0, there was good agreement between results obtained with the three systems (mean INRs within 4% of each other). In patients with INRs > 4.0, results with a human placental extract reagent (Thromborel S) were similar to those obtained with a rabbit brain thromboplastin (IL PT Fib Hs Plus); mean INRs were 6.30 and 6.32 respectively (not significant). Results with Innovin (mean INR: 7.67) were significantly (P < 0.001) greater (on average by 22%) than those obtained with the other two materials. The discrepancy between results with different reagents negatively correlated with factor VII levels. Thus, the lower the factor VII level, the greater was the discrepancy between INRs. Unexpectedly, there was a positive correlation between factor V level and the difference between INRs with different reagents. Thus, the higher the factor V level, the greater was the discrepancy between INRs. The effect of these differences at higher INRs on patient management is unknown, but the recently revised UK guidelines recommend that management of these patients should be influenced by clinical factors, reducing the relative importance of discrepancies between results obtained with different systems.

Anticoagulants↗

PubMed1996

Immunofluorometric assay of prostaglandin D synthase in human tissue extracts and fluids.

A two-site sandwich-type assay for human prostaglandin D (PGD) synthase (beta-trace) was developed with two monoclonal antibodies and using time-resolved fluorometry as the detection technique. The assay is precise (CVs < 10%), accurate, and highly specific for PGD synthase and has a detection limit of 0.05 microgram/L. Using this assay, we measured PGD synthase concentrations in serum, urine, amniotic fluid, cerebrospinal fluid (CSF), seminal plasma, breast cyst fluid, breast discharge fluid, breast milk, and breast tumor extracts. The highest concentrations were found in CSF. We identified proteolytic degradation of PGD synthase in amniotic fluid. Fetal tissues contained various amounts of the enzyme, with the highest values being found in brain and heart. In placental extracts, PGD synthase content was greatest at 11-28 weeks of gestation-in accordance with the concentrations measured in amniotic fluids for this gestational period. We conclude that PGD synthase is ubiquitous and is present in many fluids and tissues of adults and fetuses. This first quantitative and sensitive assay of PGD synthase should facilitate expansion of knowledge on this enzyme and possibly will have applications for diagnosis and monitoring of human diseases.

Adult↗

PubMed1988

Immunoreactive growth hormone-releasing hormone in rat placenta.

It has been shown that immunoreactive and biologically active GH-releasing hormone (GHRH)-like material is present in rat placenta. To investigate the role of placental GHRH, we measured it in human and rat placenta of different gestational stages, using specific RIA systems. GHRH and somatostatin contents in median eminence, pituitary GH contents, and plasma GHRH levels were also quantified in rats. Immunoreactive GHRH was detectable in rat placenta [13 days of gestation, 1.4 +/- 0.4 (+/- SD); 16 days, 1.4 +/- 0.2; 20 days, 1.7 +/- 0.4 ng/g] but not in human placenta (less than 0.06 ng/g in both full-term and mid-term placenta). GHRH concentrations in rat placenta did not change significantly during pregnancy, but total contents increased progressively in relation to placental growth. GHRH and somatostatin contents in median eminence of pregnant rats were not different from those of control female rats. In contrast, rat pituitary GH contents in pregnant rats were significantly lower than those of control female rats. Immunoreactive GHRH was not detectable in plasma of either pregnant rats or nonpregnant rats. Molecular sieve chromatography revealed two peaks of immunoreactive GHRH in rat placental extracts: a major peak eluted in the position of synthetic rat GHRH and a minor peak in the higher molecular weight region. In contrast, a single peak in the position of rat GHRH was observed in rat median eminence extracts. Detection of immunoreactive GHRH in rat placenta but not in human may suggest that the mechanism of GHRH gene expression in placenta is species specific. Failure of detection of immunoreactive GHRH in rat maternal circulation suggests that placental GHRH may not affect the maternal hypothalamic pituitary axis. Presence of high molecular weight materials of immunoreactive GHRH in rat placenta but not in median eminence suggests that posttranslational processing of the GHRH precursor molecule may be different in the two organs. Placental GHRH may have a paracrine function or may be secreted into fetal circulation and contribute to fetal growth.

Animals↗

PubMed2003

Demonstration of a non-steroidal, non-inhibin factor in the ovine corpus luteum of pregnancy that reduces pituitary responsiveness to GnRH-induced LH secretion in vitro.

The decline in pulsatile LH secretion and pituitary responsiveness to GnRH as pregnancy advances may be due to non-steroidal factors secreted by the ovine corpus luteum of pregnancy. Corpora lutea from ten ewes on days 70-80 of gestation were homogenized, charcoal-treated and, together with charcoal-treated follicular fluid from superovulated women, were subjected to inhibin immunoaffinity chromatography, reducing dimeric inhibin A and B by >90% and abolishing inhibin bioactivity. These preparations were investigated using cultures of rat pituitary cells. GnRH-induced LH and FSH secretion in vitro was reduced by ovine corpus luteum extract and human follicular fluid by 47+/-5% and 42+/-5% of control LH and by 37+/-5% and 50+/-10% of control FSH, respectively (P<0.001). Extracts prepared from corpora lutea and placentae that were collected on days 50, 90 and 120 of pregnancy (five ewes per stage of pregnancy) showed increased GnRH-induced LH-suppressing bioactivity, particularly in the case of the placental extracts, with a threefold increase in activity. When partially purified by pseudochromatofocusing, GnRH-induced LH-suppressing bioactivity in extracts of ovine corpora lutea was identified at pH 5.40 and 5.77. Although these values are similar to published gonadotrophin surge-attenuating factor (GnSAF) bioactivity pI values, a GnSAF-blocking antiserum had no consistent effect on ovine corpus luteum extract GnRH-induced LH-suppressing bioactivity. It was concluded that the ovine corpus luteum of pregnancy contains a non-steroidal, non-inhibin factor, probably not GnSAF, that has the ability to reduce pituitary responsiveness to GnRH in vitro.

Animals↗

PubMed1993

Purification, characterization, and cellular localization of the 100-kDa human placental GTPase-activating protein.

Human placenta contains, in addition to the ubiquitous p120-GTPase-activating protein (GAP), another isoform of 100 kDa, which is specific to this organ. We have established a method for purifying this placental p100-GAP to near homogeneity. The purified p100-GAP allowed the preparation of polyclonal and monoclonal anti Ras-GAP antibodies. Two monoclonal antibodies were selected for a two-site enzyme immunoassay. This simple and accurate assay in turn facilitated the detection of the GAPs during purification. The purified p100-GAP has a specific activity identical to and catalytic properties similar to those of native p120-GAP. Sequence analysis of p100-GAP revealed almost total identity to the known corresponding sequences predicted by the cDNA. The purified p100-GAP kept its activity for 1 year when stored at -80 degrees C. Our immunometric assay showed GAP to be present in human placental extracts at the exceptional abundance of about 0.1% of the total protein content. Quantitative assays showed p100-GAP to be up to 10 times more abundant than p120-GAP. Use of our antibodies allowed the specific localization of placental GAPs to cytotrophoblasts and in the syncytiotrophoblast barrier. Hence p100-GAP is shown to be found only in trophoblasts. The large quantity of p100-GAP in trophoblasts suggests that it may play a regulatory role in the proliferation or the differentiation of this cell type.

Amino Acid Sequence↗