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At least 433 records · Page 24Linked to original sources
PubMed2005

Differential activation of mitogen activated protein kinases and nuclear factor-kappaB in lipopolysaccharide-treated term and preterm amnion cells.

Intrauterine exposure to amniotic sac infection elicits an inflammatory response from the fetus, which is associated with elevated levels of fetal plasma proinflammatory cytokines, i.e. interleukin-6 (IL-6). We have recently demonstrated that the severity of fetal inflammatory response in terms of gestation period is greater in preterm fetuses than in term fetuses. The activation of mitogen activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappaB) is known to be associated with up-regulation of proinflammatory cytokine gene expression in many cell types. In the present study, therefore, we studied patterns of MAPK and NF-kappaB activation following treatment with bacterial lipopolysaccharide (LPS) in amnion cells obtained from placentas of varying gestational ages to assess whether or not MAPKs and NF-kappaB are differentially regulated during gestation. MAPK phosphorylation was investigated by immunoblot analysis with phosphospecific antibodies. Transient phosphorylations of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) were observed in LPS-treated amnion cells, with the degree of phosphorylation being more pronounced in preterm cases. The results of NF-kappaB-dependent reporter gene expression and electrophoretic mobility shift assay (EMSA) of NF-kappaB were similar to those of ERK 1/2 and JNK activity. To assess whether the results of in vitro observations reflected in vivo results, we further analyzed amniotic fluid and cord blood IL-6 levels in preterm deliveries with placental inflammation. The analysis also revealed a significantly higher level of IL-6 in cases of </=31 weeks gestation when compared with those of more than 31 weeks (P<0.001). All these findings strongly suggest that there is an inverse relationship between gestational age and fetal inflammatory response during human gestation, and that differences in the intensity of MAPK activation and NF-kappaB-dependent transcription pathways are elements of the major underlying mechanism.

Adult↗
PubMed1996

An electron microscope study of the interaction between Trichomonas vaginalis and epithelial cells of the human amnion membrane.

The mechanism of cytopathogenicity of Trichomonas vaginalis is not well established. Adhesion of T. vaginalis to human epithelial cells is considered a prerequisite for parasitic infection and its pathogenic effect. To investigate cytopathological changes in the host caused by T. vaginalis infection, human amnion membrane was used as an in vitro model. T. vaginalis strain WAA38 from axenic culture was allowed to interact with the epithelial layer of the human amnion membrane for 6 and 9 h. Structural changes resulting from the interaction between parasite and host cells were studied with transmission (TEM) and scanning (SEM) electron microscopy. Analysis of the electron microscope data showed that T. vaginalis established contact with the host cells as early as after 6 h of incubation; however, a close attachment of parasites to the epithelial cells occurred only after 9 h. Amoeboid T. vaginalis formed numerous cytoplasmic extensions and adhered to the epithelial cells mostly through the portions of their body opposite the undulating membrane. A dense network of microfilaments was seen at the site of contact between T. vaginalis and epithelial cells. Damaged and desquamated epithelial cells were seen with TEM and SEM only in the areas where parasites were in direct contact with target cells.

Amnion↗
PubMed1981

A study of angiotensin II binding sites in human placenta, chorion, and amnion.

The binding of tritiated angiotensin II to 20,000 x g particulate tractions of human placenta, chorion, and amnion was investigated. Binding to particles from the three tissues reached equilibrium within 10 minutes at 29 degrees C and was displaced by the addition of 1,000-fold excess of unlabeled angiotensin II. Scatchard analysis of the data showed that two classes of binding sites were present in the placental preparation. For the high-affinity site, values of 9 x 10(-9) M and 300 fmoles/mg of protein were obtained for the dissociation constant and the binding capacity, respectively. There was little specific binding in chorion and amnion.

Amnion↗
PubMed1987

Prostaglandin E2 release on the fetal and maternal sides of the amnion and chorion-decidua before and after term labor.

Release of prostaglandin E2 on each of the fetal and maternal sides of the fetal membranes (8 cm2) from term cesarean (no labor) and spontaneous vaginal (labor) deliveries was studied with the use of dual-compartment perfusion chambers. Postlabor amnion released significantly (p less than 0.05) more total prostaglandin E2 (5.66 +/- 1.02 ng, mean +/- SEM) than prelabor tissue (3.34 +/- 1.76 ng) with equivalent prostaglandin E2 levels being released on both sides. A net decrease (p less than 0.001) in prostaglandin E2 release by chorion-decidua was identified after labor (fetal = 0.12 +/- 0.05 ng; maternal = 0.17 +/- 0.09 ng) when compared with that before labor (fetal = 1.28 +/- 0.69 ng; maternal = 2.31 +/- 0.56 ng). Amnion-chorion-decidua released more prostaglandin E2 on the fetal side after labor (2.37 +/- 1.43 ng) than prior to labor (1.49 +/- 0.60 ng); however, prostaglandin E2 on the maternal side was significantly less (p less than 0.05) after labor (0.24 +/- 0.12 ng) when compared with that of the prelabor membrane (2.03 +/- 1.08 ng). Elution of prostaglandin E2 from preincubated membranes and endogenous membrane prostaglandin E2 content showed similar results. Thus concentrations of prostaglandin E2 on the maternal side of the fetal membranes appear diminished after spontaneous labor despite an increased release from the fetal surface.

Amnion↗
PubMed1990

CA 125 is released by human amnion cells in culture.

CA 125 was measured in the medium of human amnion cells in primary culture after confluence. The antigen accumulated as a function of time with a median value of 1897 U/mg protein after 7 days in culture. CA 125 was detectable by immunoperoxidase staining in the cells, which supports the possibility that amnion cells play a role as a source of the CA 125 found in the amniotic fluid.

Amnion↗
PubMed1991

Endothelin production by amnion and its regulation by cytokines.

Cells derived from human amnion, an avascular tissue, produced significant amounts of endothelin 1 and 2, although the rate of biosynthesis was approximately one tenth of that of human umbilical vein endothelial cells. Endothelin 1 and 2 was not produced in measurable amounts by cells derived from chorion laeve or decidua. Production of endothelin 1 and 2 by amnion cells was increased by treatment with the cytokines interleukin-1 beta, tumor necrosis factor, and interleukin-6. The biosynthesis of endothelin 1 and 2 by an avascular tissue is suggestive of a wider role for endothelins than has been recognized.

Amnion↗
PubMed1992

Regulation of intracellular Mg2+ by superoxide in amnion cells.

Changes of intracellular free Mg2+ concentration ([Mg2+]i) in human amnion cells induced by superoxide anion were determined using a highly Mg(2+)-sensitive fluorescent dye Mg(2+)-fura2 or Mg(2+)-indol. Superoxide anion, produced by addition of xanthine oxidase to hypoxanthine, induced decrease of [Mg2+]i. The decrease was significantly inhibited by an anion channel blocker, 4,4'diisothiocyano-2,2' disulfonic acid stilbene (DIDS). Superoxide dismutase (SOD), injected into cells by cell fusion, also inhibited the change of [Mg2+]i, but catalase did not. Superoxide anion induced prompt increase of intracellular pH (pHi) as well as decrease of [Mg2+]i and subsequently activated the increase of intracellular free Ca2+ ([Ca2+]i) and the release of arachidonate. In contrast to superoxide anion, NH4Cl which induces increase of pHi in amnion cells increased [Mg2+]i. The elevation of basal level of [Mg2+]i by Mg(2+)-ionophore inhibited the change of [Ca2+]i and the release of arachidonate induced by superoxide anion. These results suggest that superoxide anion, transported through anion channels into cells, decreases [Mg2+]i directly, not due to a pH-effect and that the decrease of [Mg2+]i may regulate biological functions of the cells via increase of [Ca2+]i.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

The parathyroid hormone-related protein (PTHrP) gene preferentially utilizes a GC-rich promoter and the PTHrP 1-139 coding pathway in normal human amnion.

Parathyroid hormone-related protein (PTHrP) is an oncofetal protein that is widely expressed in mammalian tissues. The PTHrP gene is a complex with three transcriptional start-sites, two TATA boxes and a GC-rich region, and three predicted polypeptide products, PTHrP 1-141, PTHrP 1-139, and PTHrP 1-173. The originally discovered form of PTHrP, PTHrP 1-141, and the classical TATA box promoters are generally assumed to be the major pathways of PTHrP gene expression. We have used the polymerase chain reaction (PCR) to study PTHrP gene expression in the human amnion. Our studies demonstrate that the GC-rich promoter is preferentially used and that PTHrP 1-139 is the major PTHrP mRNA expressed in human amnion. PTHrP 1-139 lacks the carboxy-terminal arginine and histidine residues of PTHrP 1-141; these two basic amino acids could have significant effects on the biological activity of PTHrP. These preferential pathways for PTHrP gene expression are shared by malignant and normal human tissues.

Amnion↗
PubMed1990

Purification and some properties of the fast migrating alkaline phosphatase in FL-amnion cells (the Kasahara isoenzyme) and its cDNA cloning.

One of two main FL-amnion cell alkaline phosphatase (AP), the fast migrating one (FL-APF) has been reported to be identical to Kasahara isoenzyme (K.I.), which occurs preferentially in sera of patients with primary hepatoma. We purified FL-APF of which the apparent molecular weight was 135,000 by gel filtration, and that of the subunit was 62,000 on SDS/PAGE, indicating homodimeric structure of FL-AL-APF. FL-APF was found to react with monoclonal antibody against adult intestinal AP, but not with monoclonal antibody to placental AP. We isolated FL-APF cDNA clone from FL-amnion cells, of which cDNA was 2525 base pairs in length. Nucleotide sequence of the coding region and the 3' untranslated region was identical to the sequence of human adult intestinal AP cDNA. But the untranslated region of the 5' end of the isolated clone was slightly longer than that of intestinal AP. Hence, FL-APF (K.I.) may occur by altered glycosylation of intestinal AP.

Alkaline Phosphatase↗
PubMed1991

Interleukin-6 stimulates prostaglandin production by human amnion and decidual cells.

The effects of interleukin-6 on prostaglandin production by cells from two key sources on intrauterine prostaglandin, i.e. amnion and decidua, have been evaluated. Interleukin-6 induced a concentration-related increase in prostaglandin production by amnion and decidual cells. The concentrations of interleukin-6 required for this stimulatory action are within the range measured in amniotic fluid of women with intrauterine infections and preterm labor. Hence, interleukin-6 may contribute to the mechanism of preterm labor under these conditions.

Amnion↗
PubMed1984

Adhesion of human amnion epithelial cells to extracellular matrix. Evidence for multiple mechanisms.

Human amnion epithelial cells attach and flatten slowly (approximately 65 min) onto plastic in the presence of serum but much more rapidly (20-30 min) onto subcellular matrix (SCM) deposited by the same cells. This matrix contains both fibronectin and laminin, but neither molecule on its own can reproduce its adhesive properties. Cells attach on surfaces containing fibronectin and laminin and extend filopodial and lamellipodial areas of cytoplasm without extensive flattening in the perinuclear region. Matrix deposited onto plastic by amnion epithelial cells has trypsin-sensitive and trypsin-resistant, papain-sensitive adhesion-promoting components. Cell spreading triggered by the latter but not the former can be inhibited by pretreating the adhering cells with heparin. Other GAGs are without effect. The results are discussed in terms of multiple interactions between epithelial cells and basal laminae.

Amnion↗
PubMed1991

Secretion of lysosomal hydrolases by cultured human amnion epithelial cells.

Primary microcultures of human amnion epithelial cells were established, starting from sterile term placentae. Over a period of 1 week in culture, the epithelial cells release into the extracellular medium substantial amounts of some lysosomal hydrolases, such as sphingomyelinase, N-acetyl-beta-glucosaminidase, alpha-fucosidase, beta-glucuronidase, alpha-mannosidase, and arylsulfatase. Judging from experiments conducted with the protein synthesis inhibitor, cycloheximide, the enzymes released are not newly synthesized forms, but very likely derive from lysosomes. The constitutive secretion of lysosomal enzymes, coupled with lack of immunogenicity, makes amnion epithelial cells a convenient source of enzymes for implantation in attempts of enzyme replacement therapies.

Acetylglucosaminidase↗
PubMed1989

ED-A sequence containing fibronectin in human amniotic fluid and amnion epithelial cells.

1. Human amniotic fluid fibronectin (aFn) was studied by using a monoclonal antibody 52DHl (DH) that recognizes the extra domain (ED-A) sequence of cellular Fn (cFn). 2. In immunoblotting the DH antibody reacted with a sharp polypeptide band at the top of the bulk of the diffuse aFn. Another monoclonal antibody 52BF12 (BF) against the cell binding site of Fn, recognized the whole aFn. 3. The ED-A sequence containing cFn (EcFn) formed a constant proportion in aFns from all amniotic fluid preparations studied. 4. In amniotic membranes the DH antibody revealed bright subepithelial immunofluorescence. 5. Also isolated and cultured human amnion epithelial cells were strongly positive in immunofluorescence and secreted EcFn into the culture medium as revealed by immunoblotting. 6. The results indicate that aFn is a composition of at least two different Fn subtypes of which the EcFn most probably originates from amnion epithelial cells.

Amnion↗
PubMed1986

A quantitative in vitro assay of polymorphonuclear leukocyte migration through human amnion membrane utilizing 111in-oxine.

A modified amnion chemotaxis assay is described for measurement of polymorphonuclear leukocyte(s) (PMNL) migration (random and directed) into a viable membrane. The primary modifications are the use of 111In-oxine-labelled PMNL and replacement of the nitrocellulose 'trap' filter with a type I collagen sponge. The modifications resulted in four important benefits: the quantification of PMNL migration was simplified; reader subjectivity was eliminated; the information gained of the migration process was enhanced; and the assay time was decreased. The amnion chemotaxis assay with the modifications reported should provide the means of evaluating several aspects of the inflammatory response of PMNL.

Amnion↗
PubMed1992

Advantages and pitfalls of amnion inversion repair for the treatment of large unruptured omphalocele: results of 22 cases.

This is a report of our experience with 22 cases of large unruptured omphaloceles treated by amnion inversion during the period 1973 through 1990. The method is characterized by three stages: (1) a silastic sheet is sutured directly to the skin around the amniotic membrane, under local anaesthesia, without dissection between the skin and the amnion; (2) the reduction of herniated viscera into the abdominal cavity is achieved by squeezing the sheeting using a specially modified stapler; and (3) the amniotic membrane is preserved intact, and inverted into the abdominal cavity at the time of abdominal wall closure. Of the 22 infants, 19 survived with satisfactory results. Two patients died of multiple associated anomalies, and the remaining patient died of sepsis arising at the time of the final abdominal closure. This procedure has proved to be effective and safe for high-risk patients with congenital heart diseases, anal atresia, tracheoesophageal fistula, or bronchial stenosis and prematurity. The practical aspects of the procedure, as well as its advantages and pitfalls, are illustrated.

Amnion↗
PubMed1985

Comparative study of the effects of two tocolytic agents (magnesium sulfate and alcohol) on the ionic transfer through the isolated human amnion.

The effects of two tocolytic agents (MgSO4 and ethanol) on ionic transfer through the isolated human amnion were observed and compared. The ionic transfer was estimated by conductance and ionic flux measurements. MgSO4 increased the ionic conductance (Gt) on the fetal side; it also increased the ionic fluxes from fetus to mother and from mother to fetus, but it decreased the flux ratio. Ethanol decreased Gt in both directions as well as the ionic fluxes; the flux ratio, however, remained constant. Thus, the two tocolytic agents (MgSO4 and ethanol) show a negative effect on ionic transfer through the human amnion.

Amnion↗
PubMed1978

Specific production of prostaglandin E by human amnion in vitro.

Prostaglandin production by intra-uterine human tissues has been investigated using a method of tissue superfusion. Tissues were obtained at elective Caesarean section and after spontaneous vaginal delivery. It was found that all the tissues studied (amnion, chorion, decidua and placenta) produced more prostaglandin E (PGE) and 13,14-dihydro-15-keto-prostaglandin F (PGFM - the major circulating metabolite of prostaglandin F) than prostaglandin F (PGF). Amnion produced significantly more PGE (but not PGF or PGFM) than any other tissue. Prostaglandin production by each tissue was similar whether it was taken at elective Caesarean section or after spontaneous vaginal delivery.

Amnion↗
PubMed1992

Proinflammatory cytokines interact synergistically with epidermal growth factor to stimulate PGE2 production in amnion-derived cells.

Recent evidence has implicated cytokines and growth factors in the initiation of parturition in women. In the present study, the amnion-derived cell line WISH was used to determine whether proinflammatory cytokines (interleukins 1 beta, 6, and 8, tumor necrosis factor-alpha, and granulocyte/macrophage colony stimulating factor) could amplify epidermal growth factor-induced prostaglandin E2 production. WISH cells were preincubated with cytokines (0.0001-10 ng/ml) for 60 min and then challenged with EGF (10 ng/ml) for 4 hrs after which PGE2 production was measured by radioimmunoassay. EGF, IL-1 beta and TNF-alpha alone caused a dose-dependent increase in PGE2 production, while IL-6, IL-8 and GM-CSF were ineffective over the dose range tested. When cells were preincubated with IL-1 beta or TNF-alpha, there was a dose-dependent potentiation of EGF-induced PGE2 production that was greater than the sum of EGF alone and IL-1 beta or TNF-alpha alone. In each case, the minimum dose of IL-1 beta or TNF-alpha which amplified EGF-induced PGE2 production was 0.1 ng/ml (p less than 0.05, Student's t-test). These data show that low concentrations of IL-1 beta or TNF-alpha may serve to amplify EGF-mediated PGE2 biosynthesis in amnion-derived cells and suggest that cytokines may modulate EGF function in responsive cells.

Amnion↗