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PubMed1984

Tartrate-inhibitable acid phosphatase. Purification from placenta, characterization and subcellular distribution in fibroblasts.

Tartrate-inhibitable acid phosphatase was purified to apparent homogeneity from human placenta. The enzyme is composed of two subunits with an apparent molecular mass of 48 kDa. Each subunit carries one oligosaccharide of the high-mannose/hybride type. The purified enzyme has an isoelectric point of pH 6.2. It cleaves phosphomonoester bonds at acid pH, is competitively inhibited by L-tartrate, Ki = 0.51 microM, and phosphate, Ki = 0.8mM. A monospecific antiserum raised against the purified placental enzyme precipitated 62% and 85% of the tartrate-inhibitable acid phosphatase present in extracts of placenta and fibroblasts, respectively. By means of subcellular fractionation and immunoprecipitation it was shown that the majority of tartrate-inhibitable acid phosphatase is located in lysosomes in normal and mucolipidosis II fibroblasts. In the human Hep G-2 hepatoma cells a significant fraction of the enzyme appears to be associated with non-lysosomal organelles.

Acid Phosphatase↗
PubMed1983

Monodeiodination of thyroxine to 3,3',5'-triiodothyronine in the human placenta.

We studied the characteristics of monodeiodination of thyroxine to T3 and reverse T3 in the human placenta which was obtained at normal delivery. The placentas were homogenized in cold sucrose Tris-HCl buffer, pH 7.5. The microsomal fraction was incubated at 37 degrees C in the air for 1 hr with 2 micrograms of T4 in the presence of 0.05 M DTT. The T3 and reverse T3 generated in the reaction mixture were extracted into cold ethanol and measured by RIA. Among the usual subcellular fractions of the placental homogenate, microsomes were most potent in deiodinating T4 to reverse T3, 17.9 ng/mg protein/micrograms T4/60 min. In microsome, production of reverse T3 from T4 was dependent upon protein concentration, incubation temperature, incubation time, pH and T4 concentration, and unstable to prior heating of the microsomal fraction. The production of T3 from T4 was negligible in the present system. Degradation of T3 in the human placenta was rapid. Although addition of anti-T3 antibody to the reaction mixture suppressed the degradation of T3, it had no effect on the net production of T3, suggesting that the obtained net T3 production rate had not been influenced by its degradation. Degradation of reverse T3 was negligible. These results indicate that the human placenta actively deiodinates T4 to reverse T3 enzymatically. This enzyme system might have some influence on the transplacental passage of thyroid hormone from the mother to the fetus.

Dithiothreitol↗
PubMed1984

Use of monoclonal antibodies to assign phenotypes to placental alkaline phosphatase from cultured human cell lines derived from tumors.

Monoclonal antibodies were used to type placental alkaline phosphatase (ALP) from cell lines established from malignant human tumors by incubating ALP extracts from the cells with antibodies of different allelic specificities and separating free from bound enzyme on polyacrylamide gel electrophoresis. The HeLa-derived cell lines (Hep 2 and WISH) have the type 1 ALP phenotype, while a non-HeLa cell line (HT-3) has the type 2 ALP phenotype. This approach should prove of value for the phenotyping of enzymes and proteins with poorly resolved or altered electrophoretic patterns.

Alkaline Phosphatase↗
PubMed1997

Monoclonal antibodies against the human mannose receptor that inhibit the binding of tissue-type plasminogen activator.

To study the role of the mannose receptor in cellular uptake and degradation of tissue-type plasminogen activator (t-PA), a set of five monoclonal antibodies (Moab) was generated against the mannose receptor isolated from human placental tissue. All Moab specifically recognised the 175 kDa mannose receptor in a crude placenta extract, as shown in Western blot analysis. By use of immunohistochemistry, we showed that in human placenta only the Hofbauer cells (fetal macrophages) express the mannose receptor. Epitope competition experiments indicated that the Moab bound to at least two different epitopes on the receptor molecule. Moab 14-3, 14-5, and 15-2, which are directed against one of these epitopes, strongly inhibited the interaction between the purified mannose receptor and t-PA. These Moab also inhibited mannose receptor-mediated degradation of t-PA by cultured human macrophages. The low density lipoprotein receptor-related protein (LRP) mediated t-PA degradation was not affected by the Moab. It is concluded that the Moab are useful for studying the expression of the human mannose receptor in Western blot and in immunohistochemistry, and for studying the interactions between the human mannose receptor and the mannose-containing ligand t-PA.

Antibodies, Monoclonal↗
PubMed1991

[Radioimmunoassay of progesterone in peripheral and placental blood of pregnant rabbits and guinea pigs].

Radioimmunoassay of progesterone in systemic and placental blood of pregnant rabbits and guinea pigs. 1. The level of progesterone in pregnant rabbits and guinea pigs serum was measured directly (without extraction) using a RadioImmunoAssay (RIA). 2. Hormonal concentrations in systemic blood were shown to increase with gestational age, being at their highest half-way through pregnancy (16.03 +/- 2.63 ng/ml for rabbits; 319.01 +/- 42.10 ng/ml for guinea pigs) and decreasing at the end of the pregnancy. 3. Progesterone was not detectable in rabbit placental blood, whereas a high level of this hormone was found in guinea pig placental blood, which increased with gestational age. From the 28th to the 56th post-coital day, the level increased from 143.22 +/- 13.15 to 283.30 +/- 36.84 ng/ml. 4. The method used enables to measure correctly progesterone concentrations in rabbit and guinea pig serum without extraction.

Animals↗
PubMed2004

Bovine metalloprotease characterization and in vitro connective tissue degradation.

Metalloproteases that selectively hydrolyze connective tissue proteins may tenderize meat without creating texture problems associated with myofibrillar protein degradation. Our objective was to characterize the activity of bovine placental proteases to determine whether they can improve meat tenderness through disruption of the connective tissue matrix. Enzymes were extracted, crudely purified, and proteolytic activity was assessed against gelatin and collagen under varying pH and temperature conditions using both SDS-PAGE and zymography. Gelatin zymography revealed proteolysis between 57 and 63 kDa, with decreased activity as buffer pH decreased from pH 7.4 to 5.4 (37 degrees C). Proteolytic activity was pronounced at 37 degrees C, moderate at 25 degrees C, and absent at 4 degrees C following 48-h incubation (pH 7.4). Placental enzymes were metalloproteases inhibited by excess EDTA. Maximum proteolysis was achieved in the presence of Ca2+, with or without Mg2+ and Zn2+. Absence of Ca2+ decreased proteolytic activity. Complete degradation of both the 125- and 120-kDa proteins of the alpha-chains of gelatin was achieved following enzyme incubation for 6 h at 37 degrees C or 24 h at 25 degrees C. No degradation was observed following enzyme incubation with native Type I collagen. Given the marked decrease in enzyme activity at pH 5.4 and 4 degrees C (standard industry conditions), bovine placental metalloproteases would not be expected to contribute to connective tissue degradation or improve meat tenderness.

Animals↗
PubMed1982

Maternal-fetal fat transport versus new fat synthesis in the pregnant diabetic rat.

Rats were made diabetic by the injection of streptozotocin on day 12 of pregnancy and were investigated on days 17 and 20 of pregnancy. A significant correlation between both maternal plasma triglyceride and nonesterified fatty acid levels with placental or fetal triglyceride content was found, although fetal weight did not change significantly. In order to investigate the source of the placental and fetal fat the rats received, intragastrically 24 h earlier, 1-14C-triolein (as a preformed fatty acid tracer) and tritiated water (as a marker of de novo fatty acid synthesis). Several maternal tissues, placenta, and fetuses were extracted and analysed for fatty acid radioactivity. Compared with non-diabetic pregnant rats, maternal 14C-label storage was reduced. In contrast, the placental and fetal tissues demonstrated a significant rise in 14C-label, similar in magnitude to the rise in their triglyceride content. The pattern of 3H incorporation also indicated a pronounced decrease in maternal fatty acid synthesis, but no increase in de novo fatty acid synthesis in the fetus or placenta. The findings show that fetal lipids in the pregnant rat originate both from maternal fatty acids and those synthesized in situ. The diabetes-induced increment in fetal triglyceride content is derived, however, from preformed maternal triglycerides or non-esterified fatty acids secondary to the increase in their concentration in the maternal circulation.

Animals↗
PubMed2005

Expression of maspin in gestational trophoblastic disease.

BACKGROUND: Maspin is a tumor suppressor gene whose expression is altered in neoplasia and malignancies of many tissues. In the human placenta, the maspin gene is expressed in trophoblastic cells and might act as an inhibitory regulator of trophoblastic invasion. Hence, in gestational trophoblastic disease (GTD), where there is increased propensity for invasion in the trophoblastic tissue, we hypothesized that maspin expression would be decreased. The present study aimed at investigating the expression of maspin in GTD and its prognostic significance. METHODS: Using immunohistochemical staining, we firstly studied the expression of maspin in hydatidiform moles, with gestational age-matched normal first trimester placenta used as control. A total of 38 cases of hydatidiform moles were studied, including 20 complete moles (CM) and 18 partial moles (PM). Among them, 10 cases of the CM group and 8 cases of the PM group subsequently developed gestational trophoblastic neoplasia (GTN). Immunostaining was also performed on tissue from 4 cases of choriocarcinoma and 5 cases of placental site trophoblastic tumor. Reverse transcriptase-polymerase chain reaction (RT-PCR) was further performed on RNA extracted from 10 hydatidiform moles (5 with GTN and 5 without) and 6 normal first-trimester placentae. RESULTS: In all tissue sections, nuclear expression of immunostaining signal was demonstrated, mainly in the cytotrophoblasts. The percentage of trophoblastic nuclei stained in both complete and partial moles was significantly lower than that in normal first-trimester placenta (P < 0.001). However, there was no significant difference in immunostaining between complete and partial moles (P > 0.05). There was also significantly lower expression of maspin in those cases subsequently developing GTN than those which did not (P = 0.01). Immunostaining on choriocarcinoma and placental site trophoblastic tumor showed reduced expression of maspin in all the tumor cells. Reverse transcriptase-polymerase chain reaction revealed that the expression of maspin was consistently down-regulated in all the hydatidiform mole samples. CONCLUSIONS: Our results suggest that there is down-regulated expression of maspin in gestational trophoblastic diseases, and the down-regulation is more prominent in cases developing gestational trophoblastic neoplasia. This may play a role with prognostic significance in the pathogenesis and malignant transformation of hydatidiform moles.

Choriocarcinoma↗
PubMed2002

Expression of thrombin receptors in endothelial cells and neutrophils from normal and preeclamptic pregnancies.

Thrombin receptors, i.e. proteinase-activated receptors (PARs), are expressed in endothelial cells (ECs) and neutrophils and directly affect platelet function and thrombosis. Although endothelial dysfunction and neutrophil activation have been demonstrated in women with preeclampsia (PE), the expression and regulation of PARs have not been defined in PE. In this study, we measured the expression of PARs in ECs and in neutrophils derived from normal and preeclamptic pregnancies. We also examined the effects of placental factors on PAR expression in these cells in vitro. ECs were isolated from umbilical cords (human umbilical vein ECs) from normal and preeclamptic pregnancies. Neutrophils were isolated from blood obtained from nonpregnant, uncomplicated pregnant, and preeclamptic women. Total RNA was extracted from the first-passage (P1) ECs (normal and PE) and from normal P1 ECs incubated with conditioned media derived from normal and preeclamptic placental cultures. The mRNA expression of thrombin receptor (PAR1), PAR2, and PAR3 was measured by ribonuclease protective assay. The expression of glyceraldehyde 3-phosphate dehydrogenase was used as an internal control for each sample. We found that: 1) PAR1 expression was enhanced in ECs from PE, compared with ECs from normal pregnancies; 2) PAR2 expression was expressed in PE ECs but not in normal ECs; 3) neutrophils from nonpregnant women, normal, and preeclamptic pregnancies expressed PAR2, whereas only neutrophils from normal and preeclamptic pregnancies expressed PAR1; and 4) factors released from preeclamptic placenta up-regulated PAR1 and PAR2 expression in ECs but not in neutrophils. We conclude that mRNA expression of PAR1 and PAR2 is increased in ECs derived from preeclamptic pregnancies. Up-regulation of thrombin receptor expression in neutrophils may be a unique phenomenon during pregnancy but not apparently unique to PE. Factors released from the placenta are likely candidates in regulating PAR expression in ECs and may contribute to the platelet activation and vascular endothelial dysfunction in PE.

Cells, Cultured↗
PubMed1982

Isolation, purification, and characterization of mouse placental lactogen.

Mouse placental lactogen was purified 1840-fold from BALB/c placentae from days 14-18 of gestation with an overall yield of 29%. The purification procedure included alkaline homogenization and extraction, ammonium sulfate precipitation, hydrophobic interaction chromatography on Phenyl-Sepharose, ion-exchange chromatography on CM- and DEAE-cellulose, and gel exclusion chromatography on Sephadex G-100. On 10% alkaline polyacrylamide gels, mouse placental lactogen had an Rf of 0.19. Electrophoresis in gels containing NaDodSO4 showed a single band with a mobility corresponding to a Mr of 23,000 +/- 1000. The isoelectric point, determined by isoelectric focusing in 8 M urea/5% 2-mercaptoethanol, was 7.1. When tested in the pigeon crop sac assay, 10 micrograms of mouse placental lactogen produced stimulation comparable with that evoked by 10 micrograms of ovine prolactin. In the rabbit mammary gland radioreceptor assay, mouse placental lactogen was 150% more potent than ovine prolactin in displacing 125I-labeled ovine prolactin from rabbit mammary gland membranes. Iodinated purified mouse placental lactogen could be displaced from rabbit mammary gland membranes by mouse placental lactogen, mouse prolactin, and ovine prolactin. Ovine prolactin was 45% as avid as mouse placental lactogen is displacing 125I-labeled mouse placental lactogen from rabbit mammary gland membranes. Mouse placental lactogen did not crossreact with antisera to mouse prolactin or mouse growth hormone in a radioimmunoassay.

Animals↗
PubMed1991

Purification from human pregnancy serum of a low molecular weight mitogen similar to placental lactogen and growth hormone.

Recently, we isolated from the serum of pregnant women a factor that induced rapid proliferation of a lactogen-dependent rat lymphoma cell line (Nb2). This mitogenic factor is reasonably specific to pregnancy, since it was present in serum samples from second trimester as well as term-pregnant women, but not in those of adult men or cycling females. It is unlikely that this mitogenic activity (referred to as pregnancy mitogen [PM]) is due to contamination by classical lactogens, since acetone fractionation of serum yielded a preparation devoid of placental lactogen and prolactin, as determined by radioimmunoassays. Further purification of acetone precipitates from term-pregnant serum by ion exchange chromatography and gel filtration yielded a mitogenic activity with a relative mol wt of approximately 10,000. PM activity in the NB2 cell bioassay was not affected by the presence of prolactin antiserum. However, its activity was immunoneutralized by coincubation with anti-placental lactogen serum and, to a lesser extent, anti-growth hormone serum. It appears that PM was not generated by our extraction procedure, since gel filtration of whole serum also yielded a bioactive fraction of approximately 10 kDa. PM was further purified to homogeneity by high-performance liquid chromatography. Examination of the preliminary amino acid composition of PM revealed differences from that of a bioactive fragment of growth hormone and a corresponding portion of placental lactogen, suggesting that PM could be either a molecular variant of these hormones or a novel protein.

Amino Acids↗
PubMed1984

Transuteroplacental metabolism of cortisol and cortisone during mid- and late gestation in the baboon.

We measured uterine extraction (i.e. metabolism) and transuteroplacental interconversion of cortisol (F) and cortisone (E) to determine whether metabolism across the uterus changes during pregnancy and contributes to the MCR of these corticosteroids. On day 100 (n = 4) or 170 (n = 3) of pregnancy (term = day 184), baboons (Papio anubis; 14-18 kg) were sedated with ketamine, and a constant infusion (0.38 ml/min) of 8-12 microCi [3H]F and 9-15 microCi [14C]E in 80 ml 0.9% NaCl-1% ethanol was initiated (time zero) via a maternal antecubital vein. At 60 min, animals were laparotomized, and at 70, 80, and 90 min, blood samples were obtained from right and left uterine veins and from a maternal saphenous vein. At 95 min, a transverse incision was made in the uterus, the fetus was isolated, and blood samples were obtained from the umbilical vein and artery. The cord was then clamped, and the fetus was delivered. Radio-labeled F and E were extracted from serum and purified by sequential paper chromatography, and metabolic parameters were calculated. Endogenous F and E levels were determined by RIA. In the mother, the percent conversions of E to F at midgestation (mean +/- SE; 72 +/- 4) and late gestation (65 +/- 3) were similar and exceeded (P less than 0.01) respective values for oxidation of F to E (51 +/- 7 and 46 +/- 7, respectively), indicating that maternal corticosteroid metabolism favors F formation and is unchanged during the second half of gestation. In contrast, corticosteroid metabolism across the uterus and placenta (transuteroplacental) was altered during pregnancy. At midgestation, transuteroplacental conversion of E to F (37 +/- 9) exceeded (P less than 0.05) the reverse reaction (18 +/- 3), whereas oxidation of F to E at term (28 +/- 4) was 7-fold greater (P less than 0.05) than reduction of E to F (4 +/- 1). At midgestation, essentially all of the F and E in umbilical vein was derived from maternal F. This contrasts with that observed in near-term baboons in which only 41 +/- 9% of the F and 64 +/- 8% of the E entering the fetal circulation was of maternal origin. As a result of uterine, placental, and fetal metabolism, 30% of the F and 15% of the E in maternal circulation were extracted by the uterus at both mid- and late gestation. We conclude that transuteroplacental corticosteroid metabolism changes from reduction at midgestation to oxidation at term.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Fetal magnesium homeostasis in the sheep.

The fetal plasma magnesium concentration exceeds that of the mother but the difference is small compared to that of ionized calcium concentration. Although not fully independent of changes in maternal magnesaemia, fetal magnesaemia showed a high degree of autonomy during both hypermagnesaemic and hypomagnesaemic changes induced in the ewe. As with calcium, the placental gradient is reversed after fetal thyroparathyroidectomy (TXPTX) with thyroxine replacement. During perfusion in situ of the placenta from such TXPTX fetuses isolated from the fetus itself, a stable positive placental gradient of magnesium concentration could be re-established between the perfusing blood and the maternal circulation. As with calcium, this gradient could be increased by fetal calf parathyroid extract, parathyroid hormone-related protein (PTHrP 1-141), PTHrP (1-84) but not by PTHrP (1-34). It was concluded that a mid-molecule portion of PTHrP can stimulate a putative placental pump which is responsible for the gradients of both calcium ions and magnesium across the ovine placenta.

Animals↗
PubMed1987

[Discovery of a placental variant of human growth hormone: biochemistry, physiology and implication in the secretion of hypophyseal forms].

Using two monoclonal antibodies (Mabs), each specific of two distinct hGH epitopes, we evidenced a decrease in serum 22K hGH in pregnant women and increasing levels of a GH-related factor, different from hPL. This factor was extracted from the placenta and partially characterized. Because of its binding to GH hepatic receptors with at least the potency of 22K hGH, it was named human placental growth hormone (hPGH). This hormone alone or together with hPL could therefore take over the role of the lacking pituitary GH in the mother during the last half of pregnancy.

Female↗
PubMed1976

[Induction of N-acetyllactosamine synthetase activity in the mouse mammary gland by prolactin and placental lactogen hormone].

The authors show that the ovine prolactine promote induction of N. acetyl lactosamine synthetase in tissue culture of mammary glands of pregnant mice. A crude extract of human placenta has also a lactogenic activity as tested by the same method, but in this case the blank values are very high for large concentration of crude extract. The molecular forms of HCS are tested: the slow band has a lactogenic activity, the intermediate band has no activity and the rapid band seems to be inhibitory.

Animals↗
PubMed1983

Centrifugal analyzer used for enzyme immunoassay of progesterone and choriomammotropin.

Recently we developed an enzyme immunoassay involving the use of steroid delta-isomerase (EC 5.3.3.1) as enzyme label and exclusion-affinity chromatography for rapid separation of free antigen-enzyme conjugate that bound to antibodies (J. Immunol. Methods 35: 267-284, 1980). Here we describe an automated version of this procedure, for immunoassay of progesterone and choriomammotropin (human placental lactogen) in serum with the use of a centrifugal analyzer. After incubation, suitable dilutions of sera or extract plus antiserum, conjugate, and double antibody were filtered on an estradiol affinity gel-filtration column; the enzyme activity of the filtrates was determined with the centrifugal analyzer. Results correlate well with those obtained by radioimmunoassay: r (progesterone) = 0.980, r (choriomammotropin) = 0.940. The within-run and between-run precision, specificity, sensitivity, accuracy, and speed of this system make it a useful tool for immunoassay.

Autoanalysis↗
PubMed1975

Association of fibrinogen and microfibrils with trophoblast basement membrane.

Two non-collagenous placental antigens have been detected both in membranes isolated from terminal villi by sieving and sonication and in acetic acid extracts of the villi. One of the antigens is apparently fibrinogen based on immunologic and chemical data. The second, detectable with anti-membrane antiserum after absorption with fibrinogen remained with the fibrinogen-like antigen during isoelectric precipitation at pH 4.7, electrophoresis at pH 8.6 and chromatography on DEAE cellulose. Fractions of villi in which the two antigens occur comprise more than a third of the weight of the villi. The fibrinogen-related antigen was concentrated in placental basement membranes compared to kidney and lung basement membranes. A third antigen common to the membranes, to glomerular basement membrane and to alveolar basement membrane was also detected.

Amino Acids↗
PubMedDate not supplied

Corticotrophin-releasing factor in human placenta: localization, concentration and release in vitro.

Corticotrophin-releasing factor (CRF) immunoreactivity was demonstrated by immunohistochemical staining in the cytotrophoblast of the early pregnancy placenta, in the decidua and in the amnion. This localization is different from that of adrenocorticotrophic hormone (ACTH) and beta-endorphin, which are present in the syncytiotrophoblast. The release of immunoreactive CRF was demonstrated from both early and term placental tissues in vitro. The mean amounts of CRF in the early and term pregnancy placental/decidual extracts were 0.99 +/- 0.5 ng/g and 19.7 +/- 3.1 ng/g, respectively. A slightly greater amount of CRF was found in extracts from term placentae and in cord venous plasma collected after spontaneous vaginal delivery than in those collected at elective caesarean section performed before the beginning of labour.

Adrenocorticotropic Hormone↗