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Results for “PLACENTAL EXTRACTS”

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At least 613 records · Page 34Linked to original sources
PubMed1996

Distribution of interleukin-6 in maternal and embryonic tissues during the first trimester.

Interleukin-6 (IL-6) distribution was investigated in coelomic fluid, amniotic fluid, maternal serum, decidua and placental villous tissue collected from 16 normal pregnancies between 7 and 12 weeks of gestation. IL-6 levels in fluids and tissues were measured by an immunoenzymatic assay and mouse monoclonal antibodies specific for IL-6 were used to localize immunohistochemically IL-6 in decidual and placental tissue. IL-6 was detected in all samples of coelomic and amniotic fluids and in most extracts of placental and decidual tissues. IL-6 concentration was significantly (P < 0.005) higher in the coelomic fluid than in amniotic fluid and was positively correlated with gestational age. Immunostaining for IL-6 was present in both syncytiotrophoblast and extra-villous trophoblast. IL-6 was in significantly (P < 0.001) higher concentration in decidual than in placental tissues. These data indicate that IL-6 is normally present in coelomic and amniotic fluids of early pregnancy and that IL-6 concentrations mainly result from the accumulation of trophoblastic-derived IL-6. During the first trimester IL-6 could play a role in tissue remodelling associated with placentation but also in the haematopoiesis function of the secondary yolk sac and in the generation of new vessels in placental villous tissue.

Animals↗
PubMed1993

The putative iron-responsive element in the human erythroid 5-aminolevulinate synthase mRNA mediates translational control.

The 52-nucleotide 5'-untranslated region of the human erythroid 5-aminolevulinate synthase mRNA contains a 28-nucleotide iron-responsive element-like stem-loop motif. We fused the 5'-untranslated region upstream to the coding sequence of the human growth hormone cDNA. A chimeric construct containing a mutated variant of the presumptive iron-responsive element was similarly synthesized. Translation of the wild type chimeric transcript was markedly repressed (approximately 95%) in rabbit reticulocyte lysates as opposed to the mutant. Both transcripts translated with comparable efficiency in wheat germ extracts. Purified placental iron regulatory factor selectively and markedly inhibited translation of the wild type chimeric transcript (> 90%) when tested in wheat germ extracts. By contrast, translations of either the mutant chimeric transcript or other control mRNA species were unaffected. The proximal position of the iron-responsive element relative to the cap site was shown to be important for translational control, in vitro. Our studies suggest that interaction of the iron regulatory factor with the iron-responsive element sterically hinders formation of the preinitiation complex, resulting in translational repression. Thus inactivation of the repressor protein by critical levels of iron or heme would trigger translation of this mRNA in erythroid cells. Consequently, protoporphyrin and heme synthesis would be subtly coordinated with iron supply.

5-Aminolevulinate Synthetase↗
PubMed2006

Induction of antitumor immunity through xenoplacental immunization.

Historically cancer vaccines have yielded suboptimal clinical results. We have developed a novel strategy for eliciting antitumor immunity based upon homology between neoplastic tissue and the developing placenta. Placenta formation shares several key processes with neoplasia, namely: angiogenesis, activation of matrix metalloproteases, and active suppression of immune function. Immune responses against xenoantigens are well known to break self-tolerance. Utilizing xenogeneic placental protein extracts as a vaccine, we have successfully induced anti-tumor immunity against B16 melanoma in C57/BL6 mice, whereas control xenogeneic extracts and B16 tumor extracts where ineffective, or actually promoted tumor growth, respectively. Furthermore, dendritic cells were able to prime tumor immunity when pulsed with the placental xenoantigens. While vaccination-induced tumor regression was abolished in mice depleted of CD4 T cells, both CD4 and CD8 cells were needed to adoptively transfer immunity to naïve mice. Supporting the role of CD8 cells in controlling tumor growth are findings that only freshly isolated CD8 cells from immunized mice were capable of inducing tumor cell caspases-3 activation ex vivo. These data suggest feasibility of using xenogeneic placental preparations as a multivalent vaccine potently targeting not just tumor antigens, but processes that are essential for tumor maintenance of malignant potential.

Journal Article↗
PubMed1995

Inhibition of growth hormone-releasing factor production in mouse placenta by cytokines using gp130 as a signal transducer.

The aim of this study was to investigate whether mouse placenta produces mature mouse GHRF (mGHRF) and whether cytokines regulate placental mGHRF production. Using Sephadex G-50 gel filtration chromatography and reverse phase HPLC, we identified immunoreactive mGHRF in acid-ethanol extract of placental tissues, which had chromatographic characteristics identical to those of hypothalamic mature mGHRF peptide. The major peak of immunoreactive GHRF in the medium from cultured placental cells was resolved by HPLC at a fraction identical to hypothalamic mature mGHRF. Interleukin-6 (IL-6), IL-11, leukemia inhibitory factor (LIF), and oncostatin-M, which all use gp130 as a signal transducer, significantly inhibited mGHRF secretion by cultured placental cells. However, IL-1 alpha and tumor necrosis factor-alpha had no effect on mGHRF secretion. Antibodies to IL-6 or IL-6 receptor completely blocked the inhibitory effect of IL-6 on mGHRF secretion. Anti-LIF, and oncostatin-M inhibited the expression of mGHRF messenger RNA. These results suggest that mouse placenta produces and releases the mature mGHRF, which is indistinguishable by chromatographic criteria from that produced by the hypothalamus, and that signals through gp130 lead to the inhibition of mGHRF production and release in the mouse placenta.

Animals↗
PubMed1996

Localisation of placenta growth factor (PIGF) in human term placenta.

Placenta growth factor (PlGF) is a growth factor which belongs to the vascular endothelial growth factor (VEGF) family and is known to bind to the fms-like tyrosine kinase receptor (flt-1). Using Western blot analysis a 50 kDa band was identified in placental protein extract which corresponded to PlGF homodimer. Immunoreactive PlGF was localised to the vasculosyncytial membrane and in the media of large blood vessels of the placental villi, while staining within the mesenchyme was weak and diffuse. There was moderate staining for PlGF in discrete cells in the chorion and no staining in the epithelial layer of the amnion. The maternal decidual cells showed strong staining for PlGF immunoreactive protein. PlGF mRNA was predominantly expressed by the vasculosyncytial membrane of villous trophoblast, whilst there was no apparent expression of PlGF mRNA within the villous mesenchyme. These results suggest that PlGF may be an important paracrine factor for vascular endothelial cells in placental angiogenesis and an autocrine mediator of trophoblast function.

Blotting, Western↗
PubMed1982

[Thrombogenicity of the vessel: role of microfibrils and of collagen].

Thrombogenicity of the vessel wall: role of the microfibrils and collagen. The study of platelet adhesion to rabbit aortic subendothelium preincubated with highly specific collagenase has revealed that platelets adhere to the microfibrils of the elastic lamina. To certify that an interaction between microfibrils and platelets can occur, microfibrils from two different origins were isolated: placental microfibrils extracted from the villi of human placenta, and aortic microfibrils extracted from adult bovine aorta. Both preparations were histologically homogeneous, and differed in their amino acid composition with an acidic character more pronounced for placental than for aortic microfibrils. Both preparations were able to induce platelet aggregation in plasma, but not after platelet isolation and resuspension in buffer. An interesting feature was the fact that when normal platelets were isolated, washed and resuspended in plasma from severe VWD patients, they were not aggregated by placental or aortic microfibrils. This defect was corrected after perfusion of cryoprecipitate to one patient. Moreover, monoclonal antibody directed against platelet glycoprotein Ib inhibited the aggregation of platelets to microfibrils, not to collagen; this suggested that an axis platelet GPI-FVIII/VWF-microfibrils could represent a pathway for platelet/subendothelium interaction. The adhesion of platelets to collagen seems to involve the staggering of a short amino acid sequence along a collagen fibre. This possibility arises from the requirement for the preservation of the quaternary structure of collagen in the induction of platelet adhesion/aggregation in vitro, and also from the identification and synthesis of a nonapeptide derived from type III collagen, which is also to specifically inhibit the aggregation of platelets by collagen, following its binding to platelet membrane.

Animals↗
PubMed1988

The glycosphingolipid composition of the placenta of a blood group P fetus delivered by a blood group Pk1 woman and analysis of the anti-globoside antibodies found in maternal serum.

To further define the molecules that may mediate spontaneous abortion due to maternal-fetal blood group incompatibility within the P blood group system, we have examined the fine specificities of maternal antibodies and the glycolipid antigens from the placenta of a P infant born to a Pk1 mother. Maternal antibodies obtained during therapeutic plasmapheresis were analyzed to determine their reactivities with placental glycolipid extracts on thin-layer plates. Second antibodies specific for IgM, IgG, and IgA revealed immunoglobulins of all of these classes strongly reactive with one major placental glycolipid that comigrates with globoside. GC/MS analysis confirmed that the major P-active pentaglycosylceramide of placenta has the same structure as that previously shown for the P antigen of red blood cells: GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-Cer. Serum antibodies partially purified by affinity chromatography on globoside-octyl-Sepharose specifically recognize glycolipids that contain terminal GalNAc beta 1-3Gal . . . residues and also recognize the same sequence as an internal determinant in some, but not all, glycolipids with extended globoside core regions. Thus, in the blood group P incompatible fetus, the major P antigen present in placenta has the same carbohydrate structure as the P antigen present in fetal and adult erythrocytes and might be a target for the maternal immune system.

Adult↗