Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLACENTA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2006

[Differential expression of extracellular matrix metalloproteinase inducer in normal placenta and preeclampsia placenta].

OBJECTIVE: To study the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in preeclampsia placenta and the relation with preeclampsia attacks. METHODS: Forty-four samples from pregnant women with preeclampsia (preeclampsia group), 38 samples from pregnant women with eclampsia, and 49 samples from normal pregnancies (control group) were obtained. We detected the expression of EMMPRIN in placenta by immunohistochemistry and the expression of EMMPRIN mRNA by RT-PCR. RESULTS: (1) EMMPRIN positive expression: in preeclampsia group, the moderate expression rate was 18% (8/44) and the strong positive rate was 9% (4/44); in eclampsia group moderate positive rate was 21% (8/38) and strong positive rate 13% (5/38). The difference of the two groups was insignificant (P > 0.05). In control group the moderate positive rate was 12% (6/49) and strong positive rate 82% (40/49), the difference from the preeclampsia and the eclampsia groups was significant (P < 0.001). (2) EMMPRIN mRNA expression: in preeclampsia group EMMPRIN mRNA expression in term placenta (37 - 40 gestational weeks) was 0.342 +/- 0.002, and in eclampsia group 0.344 +/- 0.023; the difference between the two groups was insignificant (P > 0.05). In control group EMMPRIN mRNA expression in term placenta (37 - 40 gestational weeks) was 0.872 +/- 0.094, the differences between the control group and preeclampsia and eclampsia groups were both significant (P < 0.001). CONCLUSION: The decrease in the expression of EMMPRIN in placenta is an important cause of preeclampsia onset; expression rate of EMMPRIN may serve as an indicator in predicting preeclampsia.

Adult↗
PubMed1983

Fetal circulation of the placenta: a comparative study of human and baboon placenta by scanning electron microscopy of vascular casts.

This study was undertaken to compare the ultrastructural appearance of the fetal microvasculature of the baboon and human placenta by the latex injection corrosion-cast technique. The general pattern of distribution of blood vessels in the placenta and the microvasculature were examined primarily by scanning electron microscopy using single and double latex (Cementex) injections of the placentae. The results of these latex injections of the baboon placenta demonstrate that (1) all the fetal arterial vessels of the baboon placenta at about three-quarters of the gestation period have a characteristic tortuosity while the venous vessels have a straight appearance, with no distinct coiling, (2) the arterial vessels exhibit a rough surface contour, (3) on the venous side the wide-calibre vessels are fairly straight and exhibit a smooth luminal surface contour, and (4) the capillary network on the arterial side is dense and highly convoluted, while on the venous side the capillary network is less tortuous. Moreover, no arterial-venous anastomosis was observed by scanning electron microscopy (SEM). The main findings based on observations of the SEM appearance of the human placental casts at three-quarter gestation and at term include the following: (1) the arterial vessels do not exhibit a marked tortuosity but do retain a rough surface contour, (2) stem vessels appear to branch at a horizontal plane before dividing into numerous smaller branches, (3) the venous side has straight, wide-calibre vessels with smooth surface contour, and (4) the capillary bed is densely tortuous on the arterial side and less tortuous on the venous side.

Animals↗
PubMed1998

[Expression of cell adhesion molecules in the extravillous trophoblast in placentas of preterm pregnancies and in placentas at term].

Invasion of the human trophoblast is regulated by cell adhesion molecules (CAM) such as integrins and members of the immunoglobulin superfamily, which also play an important role in a number of immunological reactions. Abnormal trophoblast invasion of the uterus and its arterial system has been related to preterm delivery. We examined the differences of CAM expression in the extravillous trophoblast of preterm (n = 18) and term pregnancies (n = 21). Placenta and decidua frozen sections were examined by double-staining immunohistochemistry using antibodies against the immunoglobulin superfamily (ICAM-1, ICAM-2, ICAM-3, VCAM-1), integrins (alpha 2 beta 1, alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, alpha 6 beta 1) and cytokeratin. The percentage of immunopositive extravillous trophoblast cells and the intensity of immunoreactivity for the mentioned CAM antibodies was assessed. The expression of alpha 3 beta 1, alpha 5 beta 1 and VCAM-1 (p < 0.05) in the extravillous trophoblast of preterm placentas was lower than in normal placentas, whereas the expression of alpha 6 beta 1 in the extravillous trophoblast of preterm placentas was higher than at term (p < 0.05). No differences were observed for alpha 2 beta 1, alpha 4 beta 1, ICAM-1, ICAM-2 and ICAM-3. Our results show that there is a different expression of cell adhesion molecules in the extravillous trophoblast of placentas in preterm delivery. These differences in CAM might be associated with abnormal immunological and cell-cell interactions between mother and developing fetus and thus cause preterm labor and delivery.

Antibodies, Monoclonal↗
PubMed1996

The association of cigarette smoking with placenta previa and abruptio placentae.

Smoking was recognized as having an adverse effect of pregnancy outcome as early as the mid 1950s. Smoking is a well recognized risk factor for low birthweight infants and has been implicated in preterm birth. The increased risk of both placenta previa and abruptio placentae among women who continue to smoke during pregnancy, is in general, less well recognized, but supported by numerous studies. The purpose of this article is to review the published literature dealing with the risk of placenta previa and abruptio placentae in women who smoke during their pregnancy.

Abruptio Placentae↗
PubMed1997

Expression of vascular endothelial growth factor and placenta growth factor in human placenta.

Normal development and function of the placenta requires invasion of the maternal decidua by trophoblasts, followed by abundant and organized vascular growth. Little is known of the significance and function of the vascular endothelial growth factor (VEGF) family, which includes VEGF, VEGF-B, and VEGF-C, and of placenta growth factor (PIGF) in these processes. In this study we have analyzed the expression of VEGF and PIGF mRNAs and their protein products in placental tissue obtained from noncomplicated pregnancies. Expression of VEGF and PIGF mRNA was observed by in situ hybridization in the chorionic mesenchyme and villous trophoblasts, respectively. Immunostaining localized the VEGF and PIGF proteins in the vascular endothelium, which was defined by staining for von Willebrand factor and for the Tie receptor tyrosine kinase, an early endothelial cell marker. VEGF-B and VEGF-C mRNAs were strongly expressed in human placenta as evidenced by Northern blot analysis. These data imply that VEGF and PIGF are produced by different cells but that both target the endothelial cells of normal human term placenta.

Blotting, Northern↗
PubMed1985

Can a low-lying placenta be the risk factor of cervical incompetence? A preliminary study on the relationship between placenta insertion and anatomical status of uterine cervix.

An attempt was made to verify the hypothesis that a low-lying placenta may be a factor leading to the dynamic form of cervical incompetence. A vaginal evaluation of the cervix was made in 143 pregnant women who by means of ultrasonographic method were found to have low-lying placentas. In as many as 68 out of the 143 studied cases (47.5%), the low-lying placenta coincided with a shortening of the cervix about half its normal length or in both shortening and patency of the uterocervical canal, measuring up to 2 cm in diameter (39 cases). The statistical calculations indicate that a low-lying placenta can influence cervical behaviour and that it appears to be a risk factor of cervical incompetence.

Cervix Uteri↗
PubMed1999

Hypoxia down-regulates placenta growth factor, whereas fetal growth restriction up-regulates placenta growth factor expression: molecular evidence for "placental hyperoxia" in intrauterine growth restriction.

Early placental development occurs in an environment of relative hypoxia. Hypoxia promotes angiogenesis and up-regulates vascular endothelial growth factor (VEGF) expression while it down-regulates placenta growth factor (PIGF) that possess 53% homology with VEGF. Morphological studies show poor placental vascular development and an increase in the mitotic index of cytotrophoblasts in intrauterine growth restriction (IUGR). We hypothesized that the reported relatively high oxygen level in the intervillous space in contact with IUGR placental villi will limit angiogenesis by changes in VEGF and PIGF expression and function. Western immunoblot analysis demonstrates a diametric expression of PIGF and VEGF proteins throughout pregnancy with PIGF levels increasing and VEGF levels decreasing, consistent with placental oxygenation. In IUGR placentae, the ratio of PIGF/GAPDH mRNA was increased by 2.3-fold (p < 0.03) and PIGF protein levels were also increased, (p < 0.05) as compared with gestationally-matched normal placentae. PIGF mRNA and protein were localized to the trophoblast bilayer and villous mesenchyme of the human placenta throughout gestation. In vitro studies demonstrated that increasing oxygen tension (hyperoxia) up-regulated PIGF protein in term placental villous explants, whereas hypoxic culture of a term trophoblast choriocarcinoma cell line (BeWo) down-regulated PIGF mRNA and protein and VEGFR-1 (Flt-1) autophosphorylation. The addition of PIGF-1 to a spontaneously transformed first trimester cytotrophoblast cell line stimulated DNA synthesis while PIGF-2 had little effect. VEGF and PIGF exert their biological actions by means of a common receptor VEGFR-1. In the first trimester trophoblast cells, PIGF-1 increased the association of phosphorylated extracellular signal-related kinase (ERK) with VEGFR-1 immunoprecipitates while both PIGF-1 and PIGF-2 also potentiated endogenous VEGF mediated association of phosphorylated extracellular related kinase (ERK) with VEGFR-2 (KDR). More importantly, the addition of PIGF-1 had little effect while PIGF-2 inhibited cell growth in cultured endothelial cells derived from human umbilical vein. Nitric oxide (NO) is reported to promote angiogenesis and PIGF-2 inhibited the basal release of NO from the first trimester trophoblast. The tissue expression and functional studies support the hypothesis of "placental hyperoxia" in early-onset IUGR because hypoxia down-regulates trophoblast PIGF levels, PIGF expression is increased in IUGR, and PIGF-2 inhibits endothelial cell growth. Taken together, these changes provide a cellular explanation for the observed poor angiogenesis in the pathogenesis of IUGR and show that the two PIGF isoforms may modulate trophoblast and endothelial cell function differently, possibly through potentiation of VEGF mediated activation of VEGF-2.

Cell Line↗
PubMed1991

Placenta membranacea with placenta increta: a case report and literature review.

The pregnancy of a patient with placenta membranacea associated with placenta increta and a live-born infant is described, and the literature covering placenta membranacea is reviewed. A total of 26 cases of placenta membranacea in the second and third trimesters have been reported. The condition appears to have an incidence of 1:20,000-40,000, and there have been 14 reported live births associated with this rare placental anomaly. Antepartum and postpartum hemorrhage were reported to complicate 83 and 50% of the cases, respectively. Approximately 30% of the cases involved some form of abnormal placental adherence.

Adult↗
PubMed2003

Placenta: regularization of neovascularization. Microvascularization pattern of the rabbit term placenta.

Mammalian blastocyst produces membranes that gradually attach in the endometrial epithelium and establish a close relationship between fetal and maternal circulatory systems for physiologic exchange. This fact results in the formation of a combined organ, the placenta. Placentation includes extensive neovascularization in maternal and embryonic placental tissues. Recent studies, particularly of genetically altered mice, have greatly improved our understanding of the molecular basis of the development of the vascular system. Numerous factors have been implicated in the regulation of the neovascularization process of the placenta. The aim of this article is to highlight briefly the pattern circulation of the rabbit term placenta as an example of the microvascularization of hemochorial placenta typical of humans and to summarize the main factors responsible for modulating the growth of decidual placental vessels and the vasculogenesis of the basal plate.

Animals↗
PubMed2001

Human placenta as a 'dual' biomarker for monitoring fetal and maternal environment with special reference to potentially toxic trace elements. Part 1: physiology, function and sampling of placenta for elemental characterisation.

Choice of specimen from human subjects for monitoring pollutants proven to be detrimental to human health depends on the criteria chosen, namely real-time monitoring (RTM) or long-term monitoring (LTM). Specimens such as whole blood, urine, saliva and breast milk are commonly used from living subjects for RTM of toxic metals. However, sampling blood requires an invasive procedure. On the other hand, hair (with some limitations), bone (especially for the assessment of bone seeking elements), adipose tissue (mainly for organic pollutants) and liver (for both organic and inorganic toxicants) are used as specimens for LTM. With the exception of hair, generally these specimens are obtained at post-mortem. In context of health-related biomonitoring, placenta as a specimen has not received as much attention as it deserves. It is a unique sample requiring no invasive procedure, and offers possibilities for RTM, in particular as a dual purpose specimen for evaluating the pollutant burden exerted on the mother as well as on the fetus. Obtaining representative samples of placenta for elemental composition studies is a difficult task, because of heterogeneous mix of placental cells and decidual matter tainted with maternal and fetal blood. Therefore, the present sampling practices for placental tissue, and guidelines to safeguard the validity of the sampled material have been reviewed in part 1 with the following conclusions: medico-legal and ethical matters should be properly addressed before collecting the placenta; it is advisable to collect the entire placenta even if it includes the umbilical cord; further preparatory work is to be carried out in a clean laboratory and depends upon the purpose of the investigation; homogenising the entire sample may prove to be technically challenging but this step is crucial to obtain representative samples, handling the entire sample may be unavoidable; and an alternative method of procuring representative samples would require random samples from multiple sites, pooled, homogenised and assayed to confirm homogeneity.

Adult↗
PubMed2003

Circadian expression of Mel1a and PL-II genes in placenta: effects of melatonin on the PL-II gene expression in the rat placenta.

In the mammal, melatonin regulates the seasonal and/or circadian rhythm of PRL levels. Since several members of the PRL gene family are expressed during late pregnancy, we investigated the relationship between the expression of placental lactogen (PL)-II-one member of the PRL family- and melatonin, as well as the placental expression of one of the receptors for melatonin, melatonin receptor 1a (Mel(1a())). Herein we provide the first demonstration that Mel(1a) is not only expressed in the rat placenta, but that it is spatially and temporally regulated throughout late pregnancy. In situ hybridization and Northern blot analyses show that Mel(1a) mRNA is localized in the rat placenta on gestational day 19, and is mainly restricted to the spongiotrophoblast and trophoblast giant cells. Interestingly, the junctional zone of the placenta at this time showed the strongest gene expression when the tissue was obtained at 16:00 h (daytime) and showed the least expression when it was obtained at 04:00 h (night-time). In contrast, the labyrinth zone showed the strongest expression in tissue obtained at night and showed the least expression in tissue obtained during the day. PL-II gene expression also exhibited a circadian rhythm but the direction of the fluctuation was exactly opposite to that of the Mel(1a) gene, such that at night the junctional zone had the strongest expression, while the labyrinth zone had the weakest. In vitro treatment of placental tissue with an melatonin agonist, chloromelatonin, greatly decreased PL-II mRNA levels. That Mel(1a) plays a regulatory role in the expression of PL-II in the late-pregnancy rat placenta is strongly suggested by the pattern of its own spatial and temporal expression.

Actins↗
PubMed1989

Localization of human placenta lysyl oxidase on human placenta, skin and aorta by immunoelectronmicroscopy.

Polyclonal antibodies to human placenta lysyl oxidase (Kuivaniemi et al., 1984) were used to localize the enzyme at ultrastructural level in human placenta, skin and aorta, by using the indirect immunogold method. The antibodies were tested on thin sections of tissues fixed and embedded in various experimental conditions. With all methods employed, the immunoreaction was always positive on collagen fibers in all tissues examined, independently of the age of the subjects. In placenta, the reaction was also slightly positive on matrix microfilaments and cells. In dermis, fibroblasts and elastin were scarcely positive in a normal 5 day-old child, in a child with skin hyperelasticity, and in two babies with osteogenesis imperfecta type II; whereas they were negative in two 16 and 40 year-old normal subjects. In aorta, the immunoreaction was always positive on collagen, scarcely positive on cells and on elastin of a 24 week-old fetus, of a normal child, and of two babies who died of complications associated with O.I. type II; on the contrary, the reaction was negative on cells and elastin fibers of a 16 week-old fetus, and of a normal 19 year-old girl. When present on elastin, gold particles were localized mostly inside the fibers. Contrary to what was observed by Kagan and coworkers on bovine aorta by using antibodies against aortic lysyl oxidase (Kagan et al., 1986), no specific localization of gold particles could be observed on or adjacent to the elastin/associated microfibrils. The results indicate that antibodies raised against placenta lysyl oxidase recognize collagen-associated as well as elastin-associated epitopes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2007

Avoiding manual removal of placenta: evaluation of intra-umbilical injection of uterotonics using the Pipingas technique for management of adherent placenta.

BACKGROUND: Manual removal of placenta is performed in 1-3% of cases, and whilst a well established and relatively safe procedure, it is not without complications, which include infection, hemorrhage, uterine rupture, and occasional maternal death. METHODS: A three-arm randomized controlled trial of 50 IU Syntocinon (in 30 ml N saline) versus 800 mcg misoprostol (in 30 ml N saline) versus 30 ml N saline alone (control), injected into the placental bed via the umbilical vein using the Pipingas method. A group sequential research model (triangular test: PEST4) was adopted to minimize the sample size, as retained placenta is a relatively uncommon condition. RESULTS: No significant difference in the rate of manual removal was observed between the control and Syntocinon groups. On triggering the automatic stopping rule for this arm of the trial all subsequent cases recruited were allocated to receive either Syntocinon or misoprostol. After a total of 54 cases a significant reduction in manual removal of placenta was observed in the misoprostol group, triggering the automatic stopping rule and terminating the trial. CONCLUSION: Misoprostol (800 mcg) dissolved in 30 ml N saline and administered by intraumbilical injection using the Pipingas technique significantly reduces the need for manual removal for retained adherent placenta, whereas Syntocinon has similar effectiveness to injection of N saline alone.

Female↗
PubMed2003

The expression of proprotein convertase PACE4 is highly regulated by Hash-2 in placenta: possible role of placenta-specific basic helix-loop-helix transcription factor, human achaete-scute homologue-2.

PACE4 is a member of the mammalian subtilisin-like proprotein convertase (SPC) family, which contribute to the activation of transforming growth factor (TGF) beta family proteins. We previously reported that PACE4 is highly expressed in syncytiotrophoblasts of human placenta [Tsuji et al. (2003) BIOCHIM: Biophys. Acta 1645, 95-104]. In this study, the regulatory mechanism for PACE4 expression in placenta was analyzed using a human placental choriocarcinoma cell line, BeWo cells. Promoter analysis indicated that an E-box cluster (E4-E9) in the 5'-flanking region of the PACE4 gene acts as a negative regulatory element. The binding of human achaete-scute homologue 2 (Hash-2) to the E-box cluster was shown by gel mobility-shift assay. The overexpression of Hash-2 caused a marked decrease in PACE4 gene expression. When BeWo cells were grown under low oxygen (2%) conditions, the expression of Hash-2 decreased, while that of PACE4 increased. In both cases, other SPCs, such as furin, PC5/6, and PC7/8, were not affected. Further, PACE4 expression was found to be developmentally regulated in rat placenta. By in situ hybridization, Mash-2 (mammalian achaete-scute homologue 2) mRNA was found to be expressed in the spongiotrophoblast layer where PACE4 was not expressed. In contrast, the PACE4 mRNA was expressed mainly in the labyrinthine layer where Mash-2 was not detected. These results suggest that PACE4 expression is down-regulated by Hash-2/Mash-2 in both human and rat placenta and that many bioactive proteins might be regulated by PACE4 activity.

Animals↗
PubMed1981

Compensation mechanisms for experimental reduction of the functional capacity in the guinea pig placenta. I. Changes in the maternal and fetal placenta vascularization.

After experimental reduction of its functional capacity, the placenta of the guinea pig has been studied microscopically for changes in the maternal and fetal vascularization pattern which could be interpreted as a compensation for this reduction. The functional capacity has been reduced in four ways. In the experimental groups the volume compared with untreated controls. The volume density of fetal capillaries in the labyrinthine part of the placenta was increased significantly compared with untreated controls. The surface density of these vessels, however, remained the same as in the control placentas. The volume density and surface density of the maternal lacunae did not change significantly. The conclusion is that after experimental reduction of its functional capacity the only structural modification in the guinea pig placenta involving the maternal and fetal vascularization, which can be interpreted as a compensation mechanism, is a widening of the fetal capillaries in the labyrinth.

Animals↗
PubMed1990

Isolation of plasminogen activator inhibitor-2 (PAI-2) from human placenta. Evidence for vitronectin/PAI-2 complexes in human placenta extract.

Plasminogen activator inhibitor-2 (PAI-2), found in human placenta and pregnancy plasma, was prepared in a highly purified and functionally active form from human placenta. The purification was achieved by a combination of Rivanol and ammonium sulfate precipitation, followed by chromatography on DEAE Affigel Blue, hydroxylapatite and phenylalanine-Sepharose. PAI-2, which is precipitated by low Rivanol concentrations, can be selectively redissolved from the pellet by increasing the Rivanol concentration in the presence of a reducing agent, i.e. dithiothreitol. The purified protein shows a molecular mass of 45 kDa in SDS PAGE, cross-reacts with monoclonal antibodies against PAI-2 (Mab'PAI-2), and inhibits the amidolytic activity of urokinase-type plasminogen activator (u-PA) towards the chromogenic substrate Glu-Gly-Arg-pNA (S-2444). The specific activity of the purified inhibitor was 52,300 units/mg, attaining 71,000 units/mg in peak fractions. In the immunopurification of placental extract on anti-PAI-2 Sepharose, the eluate showed the expected reaction with Mab' PAI-2, and it also cross-reacted with anti-vitronectin serum. In order to complement these results, anti-vitronectin Sepharose was used for immunopurification of placenta extract. In Western Blot experiments the eluates of anti PAI-2 Sepharose and anti-vitronectin Sepharose both showed a heterogeneous pattern of high molecular weight bands recognized by either polyclonal antiserum against vitronectin or Mab'PAI-2. In either case, reduction of the eluates releases mainly a 45-kDa band, which is recognized by Mab'PAI-2, or 80-kDa and 76-kDa bands recognized by anti-serum against vitronectin. These data suggest that the predominant form of PAI-2 in placenta extract is heterogeneous and of high molecular mass, containing complexes in which vitronectin is covalently bound to PAI-2 by disulfide bridges.

Blotting, Western↗
PubMed1977

Development of trophoblast and placenta of the mouse. A reinvestigation with regard to the in vitro culture of mouse trophoblast and placenta.

At 5 days post conceptionem (p.c.) shortly after implantation, giant cell transformation starts at the abembryonic pole of the blastocyst, spreading over the mural trophoblast; 1 day later, the first ectoplacental giant cells appear at the base of the fast growing ectoplacental cone (derived from the polar trophoblast). Giant cell transformation expands over it periphery. Thus, by the 8th day p.c., the conceptus is separated from the maternal tissue by a continuous layer of giant cells, variable in thickness. Giant cells reach their greatest size by 10 days p.c. in the mural tophoblast and by 12 days p.c. in the chorioallantoic placenta. They are probably no longer formed after that stage. Around the 8th day p.c., the allantois reaches contact with the ectoplacental cone, which develops into the chorioallantoic (definitive) placenta. At 9 days p.c., its four zones can already be discriminated: chorionic plate, labyrinth, junctional zone (trophospongium), and zone of giant cells, respectively. Within the next day, the chorioallantoic placental circulation is established. The yolk sac placental circulation is established by the 9th day p.c. The villi of the proximal layer of the yolk sac increase in size and number, and their capillary network becomes more dense until the 12th to 14th day p.c. This provides evidence that the yolk sac placenta exerts its function--to a certain extent--beyond the establishment of the definitive placenta. Around the 14th day p.c., the placental labyrinth reaches its definitive features. Fetal capillaries in the labyrinth, branching from unbilical blood vessels within the septa of connective tissue are surrounded by trophoblast cells. They form a dense vascular network bathing in maternal blood. The structures of the placental zones remain almost the same during further development, the borders becoming sometimes little blurred. Adjacent to the chorionic plate, subchorionic clefts appear at the 14th day p.c. These clefts become confluent to form the intraplacental space, regularly communicating with the yolk sac cavity. At the end of gestation (19th day p.c.) there is a considerable amount of eosinophilic material ('fibrinoid') between the zone of giant cells and the decidua, probably produced by the giant cells.

Animals↗