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PubMedDate not supplied

Observations on the separation of SP1 alpha and SP1 beta by affinity chromatography.

SP1 antigens in late pregnancy blood, in placental extracts and in acidified plasma have been purified on positive affinity chromatography columns with immobilized SP1 antiserum and on negative affinity columns with immobilized antihuman non-pregnancy serum. Both SP1 alpha and SP1 beta are bound by the positive column but only SP1 alpha is bound by the negative column. This is adduced as further support for the view that SP1 alpha is formed by the combination of SP1 beta with a protein present in non-pregnancy serum.

Chromatography, Affinity↗

PubMed1987

Water homeostasis and vasopressin release during rodent and human gestation.

Body tonicity decreases during both human and rodent gestation, manifested by a decrease in Posm of approximately 10 mosm/kg. In humans, the decrease in the osmotic threshold for thirst may precede decrements in the arginine vasopressin (AVP) secretory threshold by several weeks, whereas the metabolic clearance rate of AVP appears markedly increased in the third trimester. The cause of these osmoregulatory changes are unclear, since through 1986 we have been unable to implicate placental extracts, estrogens, progesterone, prolactin, angiotensin II, and certain endorphins in the decreased Posm observed during rat pregnancy. Changes also occur in volume-AVP secretory relationships in pregnancy. For instance, the volume-sensing AVP release mechanisms are altered during gestation in Sprague-Dawley rats in such a way that the increased intravascular volume is recognized as normal.

Animals↗

PubMed1997

In vitro permeation of human chorioamniotic membranes by Campylobacter jejuni.

In vitro penetration of human chorioamniotic membranes by Campylobacter jejuni was investigated by an organ culture model. Membrane permeation was detected by an immunoperoxidase technique and viable bacterial counts of membrane homogenates. Human clinical isolates of C. jejuni inoculated on the maternal side of the membranes penetrated to the fetal side suggesting that chorioamniotic membranes constituted a weak barrier against Campylobacter infection. Chicken fecal isolates did not penetrate chorioamniotic membranes. In vitro culture conditions did not affect the viability of membranes. Human placental extracts and amniotic fluids enhanced the in vitro growth of C. jejuni. These results suggest that certain strains of C. jejuni may penetrate intact fetal membranes and this event may play a role in the pathogenesis of infection.

Amnion↗

PubMed2002

Development of gonadotrophins for clinical use.

The 20th century witnessed the steady development of knowledge about reproductive physiology and endocrinology in animals and humans. These advances led to the identification of higher centres governing the ovary and its follicles. Effects of X-rays on the head and other agents, or excision of the pituitary gland, led to anomalies in oestrous and menstrual cycles in animals and women, respectively. Studies on pituitary and placental extracts revealed the presence of hormones regulating the ovarian follicles and the corpus luteum for the implanting embryo. These were identified as follicle stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic gonadotrophin (HCG). Increasing understanding of the mechanisms of action of these hormones led to treatments of animals and amenorrhoeic women with FSH- and LH-containing preparations in order to induce the growth of follicles and ovulation. Human FSH-rich preparations were obtained by extracting urinary gonadotrophins from the urine of post-menopausal women, and thousands of amenorrhoeic and/or anovulatory patients were treated with human menopausal gonadotrophin (HMG) and HCG to induce multifolliculation and ovulation. The introduction of IVF greatly increased the numbers of women treated in this fashion, now including cyclic women. By the mid-1980s, following the appearance of Creutzfeld-Jakob disease in women treated with gonadotrophins extracted from human pituitaries, and other safety considerations, attempts were being made to purify urinary gonadotrophin preparations, using antibodies. Increasing interest in recombinant preparations, which were pure, highly specific and highly active preparations, characterized the last years of the 20th century and the new millennium. These preparations included recombinant FSH (rFSH), recombinant LH (rLH) and recombinant HCG (rHCG). Yet, in one sense, the recombinant preparations could change the procedures of ovarian stimulation, because they focused attention on the membranal receptor in the follicle, and how best to stimulate it. Small molecules are currently being investigated, with some proving to be very active and specific, and even capable of bypassing many parts of the receptor conformation. Here lies the immediate future of this field, utilizing small, defined molecules at low cost to stimulate follicle growth, ovulation and luteinization, and perhaps one day to remove the need for gonadotrophins in clinical work.

Chorionic Gonadotropin↗

PubMed2001

Role of placenta in the regulation of fetal erythropoiesis.

We studied erythropoiesis in newborn infants delivered by mothers with normal pregnancy and gestosis. The effects of placental extracts on hemopoiesis in JCR mice were also evaluated. Our results suggest that the placenta is involved in the regulation of fetal erythropoiesis. The placenta activates fetal erythropoiesis during physiological pregnancy, while in pregnant women with gestosis the erythropoiesis-stimulating effect of placentas was less pronounced, which probably determines low reticulocyte content in the umbilical blood.

Animals↗

PubMed2004

Role of apoptosis in functional luteolysis in the pregnant rabbit corpus luteum: evidence of a role for placental-derived factors in promoting luteal cell survival.

Corpora lutea (CL) were isolated from one rabbit ovary on days 4, 8, 16 (peak luteal function), 28 (functional regression) and 30 of pregnancy and processed for biochemical analysis of DNA integrity. Analysis of DNA integrity revealed the presence of oligonucleosomal fragments in day 28 and day 30 CL but not in day 16 CL. The extent of low molecular weight (<15 kb) DNA labeling was 6.6 +/- 0.84 fold higher in day 30 as compared to day 16 CL (mean +/- SEM; n = 4, P < 0.01). In a second series of experiments, healthy CL collected from day 16 pregnant rabbits were incubated for 2 h in the absence or presence of 250 microg/ml of placental extract (PE) obtained from day 16 and/or day 30 placentas. Analysis of DNA integrity revealed that extensive apoptosis occurred in CL incubated in medium alone and in medium containing day 30 PE. In contrast, day 16 PE significantly suppressed apoptosis vs control (70 +/- 4%). In a third series of experiments, expression of mRNA for bcl-x and bax was measured by Northern analysis of CL treated without and with day 16 PE using cRNA probes for bcl-x and bax developed in our laboratory by RT-PCR. Treatment with PE significantly reduced bax mRNA levels but did not change bcl-x mRNA levels. These studies provide evidence that functional luteolysis in the pregnant rabbit CL is correlated with the occurrence of apoptosis. The data suggest that a factor(s) derived from the placenta may be responsible for the prolongation of CL life span during pregnancy by its ability to alter the bax:bcl -x rheostat and suppress apoptosis.

Animals↗

PubMedDate not supplied

Characterization of cDNA for precursor of human luteinizing hormone releasing hormone.

Human reproduction is controlled by the hypothalamic-pituitary-gonadal axis laid down early in fetal development. Luteinizing hormone releasing hormone (LHRH), also termed gonadotropin releasing hormone (GnRH), is a decapeptide and is a key molecule in this control circuit. It is produced by hypothalamic neurones, secreted in a pulsatile manner into the capillary plexus of the median eminence and effects the release of luteinizing hormone and follicle stimulating hormone from gonadotropic cells in the anterior pituitary. The peptide may have further functions, including behavioural ones, as LHRH or LHRH-like immunoreactivity has been found in gonadal tissue, placenta and the central nervous system, and exogenously administered LHRH is shown to affect behaviour. To investigate the biosynthesis of LHRH, we have now isolated cloned genomic and cDNA sequences encoding the precursor form of LHRH, the existence of which had been suggested from chromatographic studies of hypothalamic and placental extracts. These DNA sequences code for a protein of 92 amino acids in which the LHRH decapeptide is preceded by a signal peptide of 23 amino acids and followed by a Gly-Lys-Arg sequence, as expected for enzymatic cleavage of the decapeptide from its precursor and amidation of the carboxy-terminal of LHRH.

Amino Acid Sequence↗

PubMed2001

Molecular characterization of a phosphatidylcholine-hydrolyzing phospholipase C.

While searching for a phospholipase C (PLC) specific for phosphatidylcholine in mammalian tissues, we came across such an activity originating from a contamination of Pseudomonas fluorescens. This psychrophilic bacterium was found to contaminate placental extracts upon processing in the cold. The secreted phosphatidylcholine-hydrolyzing PLC was purified by a combination of chromatographic procedures. As substrates, the enzyme preferred dipalmitoyl-phosphatidylcholine and 1-palmitoyl-2-arachidonoyl-phosphatidylcholine over phosphatidylinositol. The active enzyme is a monomer of approximately 40 kDa. As for other bacterial PLCs, the enzyme requires Ca2+ and Zn2+ for activity; dithiothreitol affected the activity due to its chelation of Zn2+, but this inhibition could be compensated for by addition of ZnCl2. The compound D609, described to selectively inhibit phosphatidylcholine-specific PLCs, caused half-inhibition of the P. fluorescens enzyme at approximately 420 microM, while 50-fold lower concentrations similarly affected PLCs from Bacillus cereus and Clostridium perfringens. Partial peptide sequences obtained from the pure P. fluorescens enzyme after tryptic cleavage were used to clone a DNA fragment of 3.5 kb from a P. fluorescens gene library prepared from our laboratory isolate. It contains an ORF of 1155 nucleotides encoding the PLC. There is no significant sequence homology to other PLCs, suggesting that the P. fluorescens enzyme represents a distinct subclass of bacterial PLCs. The protein lacks cysteine residues and consequently contains no disulfide bonds. Interestingly, P. fluorescens reference strain DSMZ 50090 is devoid of the PLC activity described here as well as of the relevant coding sequence.

Amino Acid Sequence↗

PubMed2001

Inhibin subunits mRNA expression level in human placenta from normal and Down's syndrome pregnancies.

In order to study the mechanisms leading to increased inhibin A and activin A in maternal serum with advancing gestation and increased inhibin A in Down's syndrome pregnancy, the mRNA expression level of inhibin and activin subunits was quantitatively studied in human placenta using Northern blot and semiquantitative RT-PCR analysis. The corresponding protein level was also determined by specific ELISAs for inhibin A, inhibin B, activin A and inhibin pro alphaC in placental extracts. Normal placenta (n=27) showed a slight significant increase in alpha and betaA subunit mRNA levels in term pregnancy, with no change of the corresponding protein level. Placenta from Down's syndrome pregnancies (n=6) did not differ from controls in either mRNA expression or corresponding protein levels. In conclusion, there is a dissociation between inhibin and activin subunit mRNA levels and the corresponding protein levels in maternal serum, and Down's syndrome inhibin A increase is not explained by mRNA expression upregulation. In an additional study, ovarian cortex tissue from term pregnancies (n=3) were examined. Only the alpha subunit mRNA was expressed, at a higher level than in the placenta, suggesting that ovary could be a source of inhibin pro alphaC during pregnancy.

Adult↗

PubMed2003

Expression of pregnancy-associated plasma protein-A (PAPP-A) during human villous trophoblast differentiation in vitro.

Pregnancy-associated placental protein-A (PAPP-A), first isolated from maternal serum, has been identified as a metalloprotease cleaving insulin-like growth factor binding protein-4 (IGFBP-4). The source of PAPP-A during pregnancy is unclear. We therefore investigated PAPP-A expression during in vitro human villous cytotrophoblast cell (CT) differentiation into syncytiotrophoblast (ST). CT were isolated from normal first trimester, second trimester and term placentae (n=10) and cultured to form ST. PAPP-A mRNA was quantified by real-time PCR, and PAPP-A protein expression was studied by immunocytochemistry and TRACE technology with specific monoclonal antibodies. PAPP-A mRNA expression in total placental extracts increased during the course of pregnancy. PAPP-A protein was detected in the cytoplasm of both CT and ST. ST formation in vitro was associated with a 19-fold increase in PAPP-A mRNA expression and an 8-fold increase in PAPP-A secretion into the culture medium. No significant difference in PAPP-A production was observed between cultured cells isolated from early and term placentae. In conclusion, PAPP-A production in vitro, is associated to the differentiation of villous cytotrophoblast cells into syncytiotrophoblast, independently of the age of gestation.

Adult↗

PubMed1997

Preliminary characterization of a placental factor inhibiting breathing in fetal sheep.

Previous studies have revealed a placental extract that inhibits breathing in fetal sheep. In the present study of 29 chronically instrumented sheep at 132+/-1 days of gestation, infusion of the 1-10 kDa extract inhibited breathing in 76% of the experiments whereas Krebs' solution inhibited it in 24%. It retained this activity after 6 months of freezing, after lyophilization, and upon lowering the pH during purification from 8.0 to 4.0, but it inhibited breathing in only 35% when the pH was lowered to 2.0. A significant dose-dependent effect was observed from a 16-fold dilution to a 4-fold concentration. Treatment of the extract with proteinase K or boiling reduced the activity to 30% or 26% inhibition, respectively. The activity was not adsorbed to an ion-exchange column at pH 7.0 or 8.0, but it was at pH 9.0 and it eluted with increasing NaCl concentrations. On a polyacrylamide gel the activity was eluted at a K(av) of 0.66 (82% inhibition), corresponding to between 2.5 and 4.5 kDa. These findings suggest that a peptide produced by the placenta, with a molecular mass between 2.5 and 4.5 kDa, inhibits fetal breathing.

Animals↗

PubMed1981

Detection of enzyme polymorphism by using monoclonal antibodies.

Six monoclonal antibodies against human placental alkaline phosphate [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1], a highly polymorphic enzyme, were tested for reactivity against a panel of 295 placental extracts that had been typed electrophoretically. The products of the three common alleles as well as several rare alleles could be discriminated by the various antibodies. In some cases differences between allelic products were reflected by essentially "all-or-none" reactions, but in other cases the differences were smaller and demonstrable only by quantitative analysis of the binding. Evidence for allelic differences not detectable electrophoretically was also obtained.

Alkaline Phosphatase↗

PubMed2006

Rupture of uterine scar 3 weeks after vaginal birth after cesarean section (VBAC).

Uterine scar rupture in vaginal birth after cesarean section (VBAC) usually occurs during labor or after placental extraction. We report herein the case of a patient who had a cesarean section in her first pregnancy and a VBAC in her second. The present one also ended with a normal VBAC and a documented intact scar, which then ruptured three weeks later.

Adult↗

PubMed1987

Phorbol ester induces the biosynthesis of glycosylated and nonglycosylated plasminogen activator inhibitor 2 in high excess over urokinase-type plasminogen activator in human U-937 lymphoma cells.

The tumor-promoting phorbol ester PMA induces changes in the histiocytic human lymphoma cell line U-937 akin to cellular differentiation (Ralph, P., N. Williams, M. A. S. Moore, and P. B. Litcofsky, 1982, Cell. Immunol., 71:215-223) and concomitantly stimulates the biosynthesis of plasminogen activator inhibitor 2 (PAI 2) and of urokinase-type plasminogen activator (u-PA). PAI 2 is found in a nonglycosylated intracellular and a glycosylated secreted form. The former appears to be identical to PAI 2 previously purified from placental extracts and large-scale U-937 cell cultures. The sixfold increase of PAI 2 antigen measured 24 h after PMA treatment in cell extracts and conditioned media is accompanied by an equal increase of active PAI 2 mRNA, whereas the 6 to 13-fold increase of u-PA antigen in the same samples is associated with only a 1.5-fold mRNA increase. The increase of PAI 2, but not of u-PA, biosynthesis requires transcription. A 50-fold molar excess of PAI 2 over u-PA is found in both extracts and conditioned media of PMA-treated cells. PAI 2 represents at least 0.3% of total de novo synthesized protein 24 h after induction with PMA. Thus, PAI 2, but not u-PA, is an abundant product of this precursor analogue of the mononuclear phagocyte lineage, and might represent a new marker for monocyte/macrophage differentiation.

Cell Differentiation↗

PubMed1994

Adhesive properties of osteopontin: regulation by a naturally occurring thrombin-cleavage in close proximity to the GRGDS cell-binding domain.

Osteopontin (OPN) is a secreted adhesive glycoprotein with a functional glycine-arginine-glycine-aspartate-serine (GRGDS) cell-binding domain. An interesting feature of OPN structure is the presence of a thrombin-cleavage site in close proximity to the GRGDS region. Cleavage of OPN by thrombin is likely to be of physiological importance, because cleavage of blood plasma OPN occurs naturally after activation of the blood coagulation pathway. To investigate functional consequences of OPN cleavage by thrombin, cell attachment and spreading assays were performed with uncleaved and cleaved forms of OPN. For all cell lines examined, thrombin-cleaved OPN promoted markedly greater cell attachment and spreading than uncleaved OPN. Cell attachment and spreading on thrombin-cleaved OPN was inhibited both by the soluble GRGDS peptides and an OPN-specific antibody raised to the GRGDS domain of OPN, thus implicating the GRGDS region in mediating the increased cell attachment and spreading observed on thrombin-cleaved OPN. Because the GRGDS sequence in OPN is only six residues from the thrombin-cleavage site, the data suggest that possibility that thrombin cleavage allows greater accessibility of the GRGDS domain to cell surface receptors. To investigate receptors that recognize uncleaved and thrombin-cleaved OPN, affinity chromatography was performed on placental extracts; the cell surface integrin alpha v beta 3 bound to columns constructed either with native or thrombin-cleaved OPN and was selectively eluted from each with soluble GRGDS peptide and EDTA. Moreover, adhesion assays performed in the presence of alpha v beta 3 blocking monoclonal antibody LM609 identified alpha v beta 3 as a major functional receptor for thrombin-cleaved OPN. Several lines of evidence suggest that cleavage of OPN by thrombin occurs in vivo, such as in tumors and at sites of tissue injury, and adhesion assay data presented here indicate that such cleavage is important in the regulation of OPN function.

Amino Acid Sequence↗

PubMed2005

Molecular forms and microheterogeneity of the oligosaccharide chains of pregnancy-associated CA125 antigen.

BACKGROUND: The cancer antigen CA125 has a very complex molecular architecture in terms of both protein backbone and oligosaccharide chains. In this study, we examined the molecular forms and microheterogeneity of oligosaccharide chains of pregnancy-associated CA125, as a first step towards gaining an insight into its possible involvement as a ligand in carbohydrate-dependent interactions. The glycobiochemical properties of CA125 may be of diagnostic and biomedical importance as specific markers of physiological and pathological conditions of early pregnancy, as well as targets in different therapeutic procedures. METHODS: Pregnancy-associated CA125 was characterized by gel filtration and ion-exchange chromatography, followed by lectin-affinity chromatography with a panel of plant lectins as ligands. RESULTS: CA125 antigen isolated from first trimester placental extract was found to be heterogeneous in respect to molecular mass and the existence of different glyco-isoforms. Thus, elution profiles from the lectin-affinity columns demonstrated molecular subpopulations bound with low, intermediate and high affinity. Under the applied experimental conditions, CA125 bound most strongly to Triticum vulgaris agglutinin (WGA) and Ricinus communis agglutinin (RCA), but low affinity interactions occurred with the other lectins tested. CONCLUSIONS: The assessment of the carbohydrate composition of N- and O-glycans of pregnancy-associated CA125 was in general agreement with available data on CA125 of cancer origin. The main difference was observed in reactivity to Canavalia ensiformis agglutinin (ConA) and Phaseolus vulgaris erythroagglutinin (PHA-E) binding.

Biomarkers↗

PubMed1984

Human placental DNA methyltransferase: DNA substrate and DNA binding specificity.

We have partially purified a DNA methyltransferase from human placenta using a novel substrate for a highly sensitive assay of methylation of hemimethylated DNA. This substrate was prepared by extensive nick translation of bacteriophage XP12 DNA, which normally has virtually all of its cytosine residues replaced by 5-methylcytosine (m5C). Micrococcus luteus DNA was just as good a substrate if it was first similarly nick translated with m5dCTP instead of dCTP in the polymerization mixture. At different stages in purification and under various conditions (including in the presence or absence of high mobility group proteins), the methylation of m5C-deficient DNA and that of hemimethylated DNA were compared. Although hemimethylated , m5C-rich DNAs were much better substrates than were m5C-deficient DNAs and normal XP12 DNA could not be methylated, all of these DNAs were bound equally well by the enzyme. In contrast, from the same placental extract, a DNA-binding protein of unknown function was isolated which binds to m5C-rich DNA in preference to the analogous m5C-poor DNA.

DNA (Cytosine-5-)-Methyltransferases↗

PubMed1977

Preliminary characterization of isoimmunogenic placental antigens in the rabbit.

By isoimmunization of adult virgin female rabbits with rabbit placental extracts we have demonstrated the production of humoral antibody against two antigens, Ag-1 and Ag-2. Neither antigen is a normal serum protein, nor are they allotype proteins. Ag-1 has an alpha-2 mobility and a molecular weights of about 400,000. Ag-2 exhibits a gamma mobility but was not characterized. The antibody activity directed to Ag-1 in immune sera was the complement-fixing IgG fraction. Direct fluorescence-labeled antibody technique revealed that Ag-1 is a ubiquitous intracellular antigen primarily localized in the nucleus. The fast-growing, SV-40 virus-transformed rabbit kidney cell line (TRK-1) expressed much higher levels of Ag-1 than the slow-growing, non-transformed normal rabbit kidney cell line (LLC-RK1). The possibility that elevation of Ag-1 production is associated with rapid cell proliferation is discussed.

Animals↗