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PubMed1975

Characterization of rat chorionic mammotropin.

A placental lactogen or chorionic mammotropin (rCM) has been identified in the serum of pregnant rats by radioreceptor assay (RRA). Two peaks of activity were found, the first between days 11-13 and the second between days 17-21 of pregnancy. Gel filtration of day 12 serum or placental extracts revealed two peaks of lactogenic activity, the first eluting ahead of and the second appearing immediately after 125I-hPRL (human prolactin). On the other hand, when serum or placental extracts from day 17-21 pregnant rats were fractionated in the same manner, only a single peak of lactogenic activity was eluted after 125I-hPROL. The placental concentration of rCM increased from 11 mug/g wet weight at day 12 to 74 mug/g at days 14-15, after which the concentration declined to 29 mug/g on day 21. Electrophoresis of a fraction from G-100 column of a day 12 0r day 20 placental extract or serum with a V-e/V-o ratio of 2.08 revealed a single peak of lactogenic activity by RRA with an Rf equal to 0.43. Large MW rCM (V-e/V-o ratio of 1.35) from serum had an Rf equal to 0.52 whereas the large MW species from placental extracts had a mobility similar to that of small MW fraction. The half-time disappearance rate of serum rCM on day 12 is 19.5 min compared to 1.2 min on days 17-21 of pregnancy.

Animals↗
PubMed1982

Control of luteal function during pregnancy: antiluteolytic and luteotropic properties of the developing mouse conceptus.

Eight experiments were conducted to examine the influence of the conceptus on luteal function in mice. In uterine intact pseudopregnant mice, exogenous treatment with placental extracts or pregnant mouse plasma from Day 8 or Day 10 of gestation did not prolong the life span of the corpora lutea (CL). The interestrous interval (IEI) of hysterectomized pseudopregnant mice was extended by treatment with Day 10 placental extract and was accompanied by elevated plasma progesterone, consistent with the luteotropic nature of the Day 10 conceptus. The IEI of uterine intact pseudopregnant mice was prolonged by the presence of ectopically developing blastocysts and was further extended by a treatment with Day 10 placental extracts but not by treatment with Day 8 placental extracts. Although the ectopic blastocyst delayed the effect of the uterine luteolytic mechanism, there was no indication of luteotropic activity: the ectopic blastocysts were unable to activate the CL of the estrous cycle. In addition, plasma progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured in pseudopregnant, hysterectomized pseudopregnant and pregnant mice on Day 2 through 13 post-mating. The results of these experiments suggest a two-step mechanism in prolonging luteal function during pregnancy which involves two different substances. This mechanism involves an initial signal from the conceptus which blocks the uterine luteolytic mechanism and a subsequent luteotropic stimulus from the Day 10 conceptus which extends luteal life span to approximately the length of gestation.

Animals↗
PubMed1997

Presence of a bioactive and immunoreactive growth-hormone-releasing-factor-like substance in porcine placenta.

The present study was conducted to establish whether growth hormone (GH) releasing factor (GRF) is present in porcine placenta. Various concentrations of placental extracts from sows at 90 and 110 days of gestation were added to porcine anterior pituitary cells in culture. The extract-induced GH secretion was compared to that of GRF(1-29)NH2. Experiments were also performed in the presence of the GRF receptor antagonist N alpha-acetyl(D-Arg2-Ala15) rat GRF(1-29)NH2 (10(-7) M). Significant effects on GH production were obtained with increasing concentrations of placental extracts (p < 0.001). This response was significantly diminished in the presence of the GRF receptor antagonist (p < 0.001). The effect of gestational age at the time of collection of the placenta was nonsignificant (p > 0.1). In addition, using a placental extract from 110 days of gestation, an immunoreactive GRF content of 52-63 ng/mg dry weight was detected. Altogether, the detection of an immunoreactive GRF-like substance in porcine placental extracts and the ability of these extracts to stimulate GH release in a concentration-dependent manner, likely by triggering a GRF-receptor-mediated mechanism, support the presence of GRF in this tissue.

Analysis of Variance↗
PubMed2002

Pregnancy-associated and placental proteins in the placental tissue of normal pregnant women and patients with pre-eclampsia at term.

OBJECTIVE: Pre-eclampsia is a placental disease of unknown cause. Maternal circulating concentrations of a number of protein markers are altered (mainly increased) in pre-eclampsia in comparison with controls of matched gestational age. Inhibin A and activin A were found to be elevated even before the onset of the disease. The aim of this study was to compare the levels of inhibin A, activin A: follistatin ratio, leptin, pregnancy-associated plasma protein-A (PAPP-A), human placental lactogen (HPL), placenta growth factor (PLGF) and pregnancy-specific beta1-glycoprotein (SP1) in placental extracts of normal pregnant women and pre-eclampsia patients at term. METHODS: Placental tissue from normal pregnancies (n=14) and patients with pre-eclampsia (n=13) were collected at term (> or =37 weeks of gestation) and stored at -80 degrees C. The frozen tissue pieces were homogenised and the above-mentioned proteins were measured by specific enzyme-linked immunosorbent assays. RESULTS: Placental contents of inhibin A and PAPP-A were significantly higher (P<0.05) in pre-eclampsia placental extracts compared with the controls. Activin A:follistatin ratio was higher (23) in pre-eclampsia extracts than in the controls (15). Leptin, PLGF, SP1 and HPL levels were not altered in the term pre-eclampsia placenta. Inhibin A and PAPP-A contents were increased in the placental extracts of pre-eclampsia patients. CONCLUSION: Our data suggest that the placenta, possibly by a compensatory mechanism, is at least in part responsible for the altered serum levels observed in pre-eclampsia.

Adult↗
PubMed1990

Purification and characterization of proximal sequence element-binding protein 1, a transcription activating protein related to Ku and TREF that binds the proximal sequence element of the human U1 promoter.

The promoter structure of the known small nuclear RNA (snRNA) genes contains two major effectors of transcriptional activity, a proximal sequence element (PSE) and a distal sequence element (DSE). In previous work, methidiumpropyl-EDTA-Fe(II) footprinting was used to demonstrate the existence in human placental extracts of a protein producing footprints within the PSE and the DSE of the human U1 snRNA gene. This protein (PSE1) has now been purified to homogeneity from both human placental extract and K562 cell nuclear extract. PSE1 consists of two subunits, an alpha subunit with an apparent molecular mass of 83 kDa, and a beta subunit with an apparent molecular mass of 73 kDa in K562 nuclear extracts and 63 kDa in placental extracts. Footprinting and UV cross-linking assays indicate that purified PSE1 binds to the PSE and DSE of the U1 gene. Monoclonal antibodies were prepared which specifically recognize the individual subunits of PSE1. PSE1 is immunologically similar to and shares amino acid sequence with a protein (TREF) which binds the human transferrin receptor (HTFR) promoter. An in vitro transcription system was established for a template consisting of a minimal HTFR promoter placed upstream of the human U1 snRNA-coding region and shown by immunodepletion/addback experiments to specifically require PSE1. Transcription from the adenovirus 2 major late promoter was unaffected in these experiments. This result supports a functional role of PSE1 as a transcriptional activating protein, but its role in transcription of snRNA genes remains to be established. PSE1 also has an immunological relationship to and shares amino acid sequence with the p70 and p86 subunits of the human Ku autoantigen. Ku, PSE1, and TREF may thus be identical proteins or members of a family of heterodimeric proteins consisting of related subunits. Our results support earlier proposals that Ku may be a transcriptional activator.

Amino Acid Sequence↗
PubMedDate not supplied

Human embryonal extracts modulate placental function in the first trimester: effects of visceral tissues upon chorionic gonadotropin and progesterone secretion.

We investigated the effect of human first trimester fetal visceral organ extracts upon placental function, as evidenced by secretion of human chorionic gonadotropin and progesterone in explant cultures of 7-10 weeks gestational age trophoblast. Certain alcohol/water or water extracted embryonal tissues, in highly diluted solutions (1:100-1:2,000 final) had significant effects upon secretion of both hormones. The alcohol/water extract produced an opposite effect. This inhibitory effect was also seen when pulses of the water extract were added to the superfused trophoblast. Both heat inactivation at 57 degrees C and treatment with 10 microM p-chloromercurobenzoate eliminated the inhibitory effect, which suggests that the compounds in question are proteinaceous. Also dialysis with exclusion of less than 8,000 daltons abolished the inhibitory effect seen with the untreated water extract. The alcohol/water lung extract at 9 weeks inhibited, while at 10 weeks it stimulated P4 secretion. The water extracted lung had no effect upon P4 secretion. The alcohol/water extract of kidney had no consistent effect upon hCG secretion. The water extract effect was inhibitory. The effect of alcohol/water extract at 9 weeks upon P4 secretion was inhibitory while at 11 weeks it was stimulatory. The water extract had no effect upon P4 secretion. Both alcohol/water and water extracted adrenal inhibited hCG secretion. The alcohol/water extract also increased P4 secretion, while the water extract had no effect. The alcohol/water and water extract liver had no effect upon hCG secretion. The effect of alcohol/water upon P4 secretion was markedly stimulatory, while the water extract had no effect. In conclusion, fetal visceral organs in very dilute concentrations have a significant effect upon placental hormonal secretion in vitro. In case of the lung, the active compound(s) appears to be a protein with a molecular weight of less than 8,000 daltons. The role of the human embryo in modulating early trophoblastic function is suggested.

Adrenal Glands↗
PubMed1983

Detection of immunoreactive human placental oxytocin and its contractile effect on the uterine muscle.

Freshly obtained human placentas from various periods of gestation were quantitatively analysed for their immunoreactive oxytocin (OT) content and its biological activity was examined in a Magnus apparatus by utilizing rat uterus. The mean values for placental immunoreactive OT per gram tissue increased from the first to the second trimester, maintaining its high level to term. The total content of placental OT also increased continually from the beginning of pregnancy to term. Blood levels of estrogen stimulated neurophysin (ESN) and OT were concomitantly enhanced through gestation. Placental extract and synthetic OT showed similar peaks in the elution pattern of ion-exchange chromatography through a carboxymethyl cellulose column. Synthetic OT and placental extract induced marked uterine contraction in diestrous rats. However placental extract previously incubated with OT antiserum failed to induce this effect. Though detection of immunoreactive OT by immunoassay alone does not provide definite identification of pituitary and placental OT, the present study suggests that placental immunoreactive OT could have a contracting effect on the uterine muscle.

Animals↗
PubMed2003

Double radial immunodiffusion as a tool to identify pregnancy-associated glycoproteins in ruminant and nonruminant placentae.

Pregnancy-associated glycoproteins (PAGs) are antigens synthesized in the superficial layers of the ruminant trophoblast. Initially, they were identified either as proteins released into the maternal bloodstream (where they have applications in pregnancy diagnosis) (PAG1) or as molecules binding to the LH receptor (PAG2). In this study, double radial immunodiffusion was used to test the ability of antisera raised against different PAG molecules (bovine, ovine and caprine) to react with placental extracts from nonruminants (rabbit, cat, mouse, pig, and wild pig) and ruminants (cow, ewe, and goat). Placental extracts from all nonruminants tested except rabbit reacted with anti bovine PAG2 (anti-boPAG2). Extracts of ruminant placentas reacted with different antisera, confirming the expression of various PAG molecules. According to the time at which the placentas were collected (early or middle pregnancy), the reaction differed as regards the thickness, position, and number of precipitation lines, suggesting that PAG expression varies as pregnancy progresses. Bos indicus and Bos taurus placental extracts exhibited different reactions with anti-boPAG2: a single precipitation line in the former case and two lines in the latter. This suggests differential expression of boPAG2 related glycoproteins in these two subspecies.

Animals↗
PubMed1980

Thyrotropin-releasing hormone-like bioactivity in placenta: evidence for the existence of substances other than Pyroglu-His-Pro-NH2 (TRH) capable of stimulating pituitary thyrotropin release.

The purpose of this study was to investigate the chemical nature of the TRH-like bioactivity and immunoreactivity in extracts of human placenta. Methanolic extracts of human placenta contained nearly 36 ng TRH-like bioactivity/g dried tissue. The immunoreactivity of this extract was only 3 ng/g dried tissue. Two molar acetic acid extracts of human placenta yielded 9 ng TRH-like bioactivity/g dried tissue. The immunoreactivity of these acetic acid extracts, however, was 5.5 ng/g dried tissue. When these placental extracts were subjected to gel filtration chromatography, the bioactivity was found to reside in two fractions which were distinct from synthetic TRH. Furthermore, the immunoreactivity present in these placental extracts was also chromatographically distinct from that of synthetic TRH. In conclusion, these experiments confirm the presence of substantial quantities of materials in placenta which possess TRH-like immunoreactivity and bioactivity. These results also argue that the immunoreactive fractions are not bioactive and provide firm evidence that neither the TSH-releasing substances nor the TRH-like immunoreactivity found in human placenta are identical to pyroglu-His-Pro-NH2.

Animals↗
PubMed1990

Differential modulation of the in vitro lymphocyte activation pathways by soluble and solubilized placental substances.

Soluble and detergent-solubilized placental extracts were studied for their modulatory effects upon the proliferation of lymphocytes stimulated by various activating agents. It was shown that soluble placental extract (SPE) exerted an inhibitory effect on the lymphoproliferation triggered by alloantigen or LPS but not by Con A or the combined action of PMA + calcium ionophore A 23187. This effect was also observed with SPE precipitated by 30% of ammonium sulfate (SPE30). On the other hand, a solubilized placental extract (SzPE) that was obtained by using octyl-beta-D-glucopyranoside inhibited the stimulation triggered by alloantigen, LPS, and Con A but did not affect the protein kinase C pathway. The modulatory effects were observed not only when SPE (or SPE30) and SzPE were added at the time of culture initiation but also at 24 h before or after the activating agents. Preincubation with SPE30 or SzPE immobilized on plastic surface, however, transduced an enhanced lymphoproliferative response to alloantigen and mitogen Con A but not to LPS. The above results suggest that placental substances exerted their modulatory effects by interfering mainly with the antigen or mitogen lymphoproliferation pathways.

Adjuvants, Immunologic↗
PubMed1976

Lactogenic and growth hormone-like activities in pregnancy determined by radioreceptor assays.

Factors with growth hormone and lactogenic activities have been identified in serum samples and placental extracts of 9 species using a radioreceptor assay for prolactin or lactogens (RRA-PRL) and one for growth hormone-like activity (RRA-GH). The concentrations of placental lactogen (PL) and growth hormone-like activity (GHLA) in pregnancy were different in each species. The levels of PL began to rise at or before mid-pregnancy and either remained elevated until term (hamster, goat, sheep, monkey, and human), declined gradually after reaching peak concentrations just beyond mid-pregnancy (guinea pig), or had 2 peaks of activity (mouse, rat). The peak concentrations in different species ranged from 350 ng/ml in the cow to 45,000 ng/ml in monkey serum samples. The concentrations of GHLA were similar to PL levels in the guinea pig, goat, cow, and monkey but were lower than PL levels in the sheep and human. The maximal concentrations of PL and GHLA in placental extracts varied from 1 mug/g in guinea pigs to 200 mug/g in sheep. The ratio of lactogenic/growth hormone-like activity of both serum and placental extracts varied greatly among the various species. Gel filtration studies of serum samples revealed that PL and GHLA in the hamster, mouse and rat had different elution volumes, whereas, in the remaining species, the two activities co-eluted.

Animals↗
PubMed1985

Keratinocyte growth-promoting activity from human placenta.

Extracts of term human placenta were tested for enhancement of proliferative growth of primary cultures of human keratinocytes. Saline extracts or supernatants from homogenates were dialyzed extensively, lyophilized, and tested in subcultures of keratinocytes in MCDB 153 medium with 0.1 mM Ca++ containing only defined supplements (insulin, hydrocortisone, transferrin, ethanolamine, phosphoethanolamine). Cells plated in the absence of EGF at moderately high densities (1000-3000 cells per cm2) formed colonies and grew in the presence of placental extract at 25-500 micrograms/ml. Extracts of cord serum or maternal serum were inactive, suggesting that the activity is derived from placental tissue. The activity is not EGF, since the activity in the placental extract, unlike EGF, did not promote growth at low cell density, was synergistic with EGF under some conditions, and did not produce changes in colonial morphology which occurred in the presence of EGF. Unlike keratinocyte growth-promoting activity in bovine hypothalamic extract, the activity is non-dialyzable and is destroyed at 100 degrees C. Placental extract could not replace any of the defined components of the medium and is therefore distinct from them. The presence of activity in the placenta with distinctive properties suggests that this is a previously undescribed material with growth-promoting properties for epithelium.

Cell Count↗
PubMed1984

Steroid sulfatase = aryl sulfatase C? Chromatographic and electrophoretic properties in extracts from placental microsomes and skin fibroblasts.

Although the deficiency of steroid sulfatase (STS) as well as aryl sulfatase C (ASC) activities in patients with X-linked recessive ichthyosis has been confirmed by several groups all over the world, the question whether STS = ASC is not yet completely answered. To obtain more information, Miranol H2M extracts from placental microsomes and cultured skin fibroblasts were subjected to gel permeation chromatography and polyacrylamide gel electrophoresis. STS (3H-dehydroepiandrosterone sulfate) and ASC (4-methylumbelliferone sulfate) activities were estimated in the eluted gel permeation chromatography fractions and within the same gel cylinders in half gel slices. None of these two methods allowed a separation of the two microsomal sulfatase activities. From these results and from different behavior of STS and ASC (not deficient in uncultured skin preparations of X-linked recessive ichthyosis, different kinetic properties between STS and ASC, etc.) we propose microsomal sulfatase activities to be assembled in an enzyme aggregate.

Arylsulfatases↗
PubMed1983

Human laminin isolated in a nearly intact, biologically active form from placenta by limited proteolysis.

A protein with properties of laminin has been isolated from human placental extracts by using monoclonal antibodies. Placental tissue was extracted with 0.5 M NaCl and high molecular weight proteins were isolated from the extract by salt precipitation and gel filtration on Sepharose 6B. The resulting protein fraction which contained material cross-reactive with anti-sera to rat laminin was used as immunogen to prepare hybridomas. Thirteen hybrids produced antibodies which reacted with basement membrane-associated antigens in indirect immunofluorescence of tissues. One of these, 4E10, was characterized in detail. This monoclonal antibody reacted with human laminin as shown by several lines of evidence. Immunoprecipitation from metabolically labeled culture media of a human amniotic epithelial cell line with the 4E10 antibody followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed polypeptides with Mr similar to those of rat laminin. Immunochromatography of placental extracts obtained by limited pepsin digestion yielded material with main polypeptides at 160 and 130 kilodaltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reduction. These peptic fragments cross-reacted with rat laminin in immunodiffusion and enzyme immunoassay, and a polyclonal antiserum against the fragments reacted with basement membranes in tissues in a manner identical with the 4E10 antibody. Electron microscopic images of the human peptic fragments showed structures similar to the cross-shaped images of murine laminins, although the short arms were truncated to various degrees or even absent. The isolated peptic fragments also displayed biological activity similar to that of murine laminins in that the outgrowth of neurites by neuronal cells was promoted on plates coated with the fragments.

Antibodies, Monoclonal↗
PubMed1982

Modification of thymocytes subsets during pregnancy analysed by flow microfluorometry: role of the alloantigenic status of the conceptus.

Modifications of thymus subsets during pregnancy were monitored using flow microfluorometry and fluorescein-labelled lectins or antibodies. Essentially, it was found that the percentage of peanut lectin-negative (PNA-) cells increased significantly during pregnancy. More interestingly, in the strains tested, the percentage of PNA- cells was more increased in allogeneic than syngeneic pregnancy. This PNA- increase could be mimicked by extracts from syngeneic placenta, but the largest increase in PNA- cells was always observed by injection of allogeneic placental extract, or syngeneic placental extract plus allogeneic cells. These findings suggest that the alloantigenic status of the conceptus does play a role in induction/maintenance of thymus involution, suggesting that it is not a mere hormonal phenomenon and that it could play a role in the events leading to the acceptance of the allogeneic conceptus by the maternal immune system.

Animals↗
PubMedDate not supplied

Multiple forms of rat placental lactogen-II (rPL-II): purification and partial characterization of rPL-II.

The present study was designed to develop a procedure for purifying rPL-II and a homologous radioimmunoassay (RIA) for rPL-II. Molecular profiles of rPL-II were also investigated in tissue and plasma. rPL-II was purified 3,780-fold, based on its radioreceptor assay (RRA) activity compared to ovine prolactin (0PRL), from the placenta of day 18 pregnant rats using ammonium sulfate precipitation and chromatography on phenyl-Sepharose, DEAE-TOYOPEARL 650S, AF-chelate TOYOPEARL 650M and Sephadex G-100. Electrophoretic analysis on SDS gel revealed molecular weight heterogeneity of purified rPL-II, which consisted of three proteins; a major form with a molecular weight of 20.0 K and two minor forms with molecular weights of 20.6 K and 21.0 K under non-reducing conditions. One of the minor forms of rPL-II observed under non-reducing conditions disappeared with 2-mercaptoethanol treatment and the rest of the hormones migrated as 24.5 K and 25.0 K molecular weight species, suggesting that it is a cleaved form of rPL-II. Purified rPL-II displaced 125I-labelled oPRL from binding sites on rabbit mammary gland membranes in a dose-dependent manner. rPL-II and rPRL were, respectively, 21 and 2 per cent as effective as oPRL in the displacement. Antibody to purified rPL-II was raised in rabbits and a homologous RIA for rPL-II was developed. No displacement was observed with rPRL, rGH, oPRL, and other pituitary hormones up to 1,000 ng/ml. Molecular profiles of rPL-II in the placental tissue and plasma from day 18 pregnant rats were examined by gel chromatography on Sepharcryl S-300 HR and by Western blotting. Chromatography of the placental extracts revealed a single peak, which accounted for 86 per cent of the total RIA activity. Anti-rPL-II antiserum detected proteins of at least three molecular sizes as monomeric forms with molecular weights of 20.0, 20.6, and 21.0 K in the non-reducing placental extracts. One of them disappeared with 2-mercaptoethanol treatment and other two proteins had molecular weights of 24.5 and 25.0 K, indicating monomeric heterogeneity of rPL-II in the tissue. The elution profile of day 18 plasma in RIA activity gave two major peaks; the first, eluting just after the void volume (approximate molecular weight of 530 K) accounted for 35 per cent of the total RIA activity, and the second coinciding with the same elution volume as the monomeric form in the placental extract constituted about 26 per cent of the total RIA activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗