Expression of superoxide dismutase and xanthine oxidase in myometrium, fetal membranes and placenta during normal human pregnancy and parturition

Superoxide, an agent which attenuates the half-life of nitric oxide, is metabolized and synthesized by superoxide dismutase (SOD) and xanthine oxidase, respectively. Over the last few years much work has focused on the role of nitric oxide in human parturition. The aim of this study was to determine whether the onset of human parturition is associated with a change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD), manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the uterus. Samples of myometrium, placenta, decidua and fetal membranes were obtained from women before and after the onset of labour at term. Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like immunoreactivity was detected in syncytiotrophoblast cells, villous stromal cells and endothelial cells of blood vessels in the placenta. In the myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial cells and to some vascular smooth muscle cells. In the fetal membranes we observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion, extravillous trophoblast and decidua. There was no difference in SOD enzyme activity or staining intensity for SOD between different cell types before and during labour. Xanthine oxidase immunoreactivity was identified in each of the tissues examined and again there was no difference in immunostaining in tissues obtained from women delivered before or after the onset of labour. These results show that the pregnant uterus is capable of both synthesizing and degrading superoxide and suggest that superoxide dismutase and xanthine oxidase may play a role in the maintenance of uterine quiescence during pregnancy, but not in the initiation of parturition.     

Measurement of interleukin-1 alpha and interleukin-6 in pregnancy-associated tissues

The concentrations of interleukin-1 alpha (IL-1 alpha) and IL-6 in pregnancy-associated tissues were investigated in term labour and delivery in the absence of labour (elective Caesarean section). Samples of amniotic fluid, placenta, fetal membranes, umbilical venous and, where possible, umbilical arterial blood were collected at delivery (37-41 weeks of gestation). Maternal blood was sampled during labour. Fluid and tissue extracts were assayed for IL-1 alpha and IL-6 by radioimmunoassay. Placenta and membranes were examined histologically for evidence of infection. Concentrations of IL-1 alpha and IL-6 in amniotic fluid and membrane extract, and IL-1 alpha in maternal and fetal blood, were raised after the onset of labour. Concentrations of both cytokines in the placenta remained unchanged. There was a good correlation between concentrations of both cytokines in amniotic fluid and membranes. There was also a significant correlation between concentrations of IL-1 alpha and IL-6 in amniotic fluid, placenta and membranes. It is suggested that the fetal membranes or maternal decidua, but not the placenta, internal fetal or maternal tissues, are the main sources of IL-1 alpha and IL-6 during labour.     

A digital subtraction radiography investigation of upper first molar proximal bone density changes in adolescents

The aim of this study was to characterise the localisation and staining intensity of immunoreactive (ir) interleukin-4 (IL-4) and IL-4 receptor (IL-4R) in human placenta and fetal membranes in association with pre-term and term labour, and pre-eclampsia. The data obtained in this study establish the presence of irIL-4 and IL-4R in human placenta and fetal membranes obtained from women at 25-41 completed weeks of gestation. IL-4 and IL-4R immunohistochemical staining was principally localised in villous and chorionic trophoblast, and to amnion epithelial cells. The intensity of IL-4 and IL-4R immunohistochemical staining was not significantly affected by labour status at term or pre-term (p > 0. 05), with the exception of IL-4R in the amnion (p < 0.05). In term amnion, IL-4R was only detectable following labour onset. When data were stratified with respect to the presence or absence of pre-eclampsia, no statistical difference in immunohistochemical localisation or staining intensity for either IL-4 or IL-4R could be identified for any of the tissues studied. Co-localisation of IL-4 and IL-4R within gestational tissues may indicate auto- and/or paracrine mechanisms of action for this cytokine. Tissue-specific, labour-associated induction of IL-4R may contribute to the regulation of biological effects of IL-4 within the uteroplacental unit.     

Optical measurements of nucleic acids in the presence of phenol and protein impurities

The concentrations of prostaglandin E2 and F2 alpha have been measured by radioimmunoassay in portions of cord, placenta, amnion, chorion, decidua and myometrium. The samples were obtained at defined periods of pregnancy, and the results have been compared with those obtained from the analyses of endometrial and myometrial tissue removed from women during the secretory phase of a menstrual cycle. The results showed that during pregnancy the mean concentration of prostaglandin E2 was higher (27-518%) than the corresponding value for prostaglandin F2 alpha in all tissues. At term the concentration of prostaglandin E2 (ng/100 mg wet weight of tissue, mean +/- S.D.) was higher in the umbilical cord (5-54 +/- 0-88), decidua (4-02 +/- 1-78) and myometrium (4-19 +/- 1-06), than in the amnion (2-25 +/- 1-27), chorion (1-64 "/- 0-63) or placenta (1-04 +/- 0-25). During labour there was a significant rise (P less than 0.0005, Student's 't' test) in the concentration in decidua (10-76 +/- 4-45), and to a lesser extent (P less than 0-05) in the myometrium (5-84 +/- 2-65) and amnion (4-77 +/- 2-51). The overall concentration in decidua during the first trimester (3-09 +/- 1-02) was significantly lower (P less than 0-005) than in endometrial tissue(16-82 +/- 10-13). The concentration was lower in myometrial tissue from non-pregnant subjects (2-90 +/- 2-21), than in the corresponding tissue removed at term (4-19 +/- 1-06) or during labour 5-84 +/- 2-65). The results for prostaglandin F2 alpha showed a similar pattern, but the values were significantly lower in the umbilical cord, and the percentage changes in concentration in the decidua and myometrium were of a higher magnitude.     

Progressive transformation of germinal centers and nodular lymphocyte predominance Hodgkin''s disease: a comparative immunohistochemical study

Interleukin-1 (IL-1) is a dimorphic cytokine that acts on target cells through high-affinity receptors, type I and type II. It has been implicated in the onset of term and preterm labour with associated intrauterine infection. To define better the potential action of this cytokine in the human fetal membranes and decidua, the objective of this study was to define the type(s) of IL-1 receptors present in the tissues at term, examine the tissue and cellular distribution of the receptor(s) and determine if there were any changes in their expression or distribution with the onset of labour. Tissues were obtained following elective caesarean section (n=12) or normal labour delivery (n=11). Paraffin embedded and frozen sections were examined by immunohistochemistry and in situ hybridization for evidence of the type I and type II receptors and their corresponding mRNAs. In all tissues studied the type I receptor was localized mainly to the decidua and the type II receptor was localized to the decidua and scattered cells in the amnion-chorion mesenchymal layer. In situ hybridization localized type I receptor mRNAs and type II receptor mRNAs to the decidua. The type I and type II receptor protein in the decidua showed a similar pattern of staining as that found for CD-68, a macrophage marker. The pattern of receptor expression and distribution was unrelated to the mode of delivery. No evidence for the presence of the type I or type II receptor or their mRNAs in the amnion epithelial cells or chorion laeve trophoblast was found.     

Stimulation of the switch in myometrial activity from contractures to contractions in the pregnant sheep and nonhuman primate

The process of parturition is regulated by a set of interrelated endocrine, paracrine, and autocrine systems. Many of these systems demonstrate positive feed-forward characteristics. The sequential recruitment of signals that promote the labour process demonstrates that it is not possible to attribute the designation of the factor responsible for the 'initiation of parturition' uniquely to any one signalling mechanism. For this reason we prefer to avoid the term initiation of parturition since, mechanistically, each cellular and molecular mechanism that contributes to the process is itself initiated by an earlier process. In a very real sense, the initiation of parturition can be considered to be fertilisation. Therefore we prefer to describe the key mechanisms involved as promoting, rather than initiating, the process of labour and delivery. Despite many interspecies differences, an increase in maternal plasma oestrogen in late gestation appears to play a central role in promotion of parturition. In both sheep and monkeys signals from the fetal hypothalamo-pituitary-adrenal axis increase oestrogen production by the placenta. We propose that the key fetal adrenal product is cortisol in the sheep and androgen in the monkey. Oestrogen then recruits a range of stimulators, uterotonins, that act on the prepared myometrium to initiate the switch in myometrial activity from contractures to contractions. The various mechanisms central to the process can be considered to be either, or both, activators and/or stimulators of one or more of the key terminal steps involved.     

Corticotropin-releasing hormone receptor subtype 1 is significantly up-regulated at the time of labor in the human myometrium

Circulating concentrations of CRH rise late in human pregnancy, reaching a peak at labor. The presence of functional CRH receptors, CRH-R1 and CRH-R2, in the human myometrium suggests that CRH may modulate uterine activity. We hypothesized that the number of CRH receptors would be higher in myometrium than fetal membranes (FM) and would change during labor. Myometrial samples were collected from the lower segment (LS) in nonpregnant, preterm (32 +/- 2 weeks), and term (39 +/- 1.6 weeks) pregnant patients before and at labor. Fundus and LS samples were also collected from nonpregnant, pregnant, laboring, and postpartum women. FM were collected at term and at labor. We identified CRH receptors in myometrium and FM by semiquantitative RT-PCR and immunohistochemistry. CRH-R1 messenger ribonucleic acid (mRNA) in the LS was decreased in pregnancy and increased significantly in both preterm and term labor (P < 0.05), but remained unchanged in the fundus. CRH-R2 mRNA was present in 28% of LS myometrium with no change at labor. CRH-R1 and CRH-R2 protein was localized to myometrial smooth muscle in nonpregnant and laboring patients, with lower levels at term. CRH-R1 mRNA was present in chorion and decidua, but CRH-R2 was undetectable in these tissues. We conclude that CRH-R1 is expressed preferentially in myometrium and FM. Changes in CRH receptors during labor are consistent with CRH mediating effects on myometrial activity.     

Histochemical localization of nitric oxide synthase in the human placenta

OBJECTIVES: To study localization, distribution and activity of nitric oxide synthase (NOS) in the human placenta and to speculate the action of nitric oxide (NO) during pregnancy. METHODS: NADPH-diaphorasc histochemical method was used to indicate the distribution, localization and activity of NOS in the placentae of normal term pregnancy (n = 21). Severe pregnancy induced hypertension (PIH) (n = 15), intrauterine growth retardation (IUGR) (n = 2) and villi of early pregnancy (n = 16). RESULTS: The NOS reactive product called blue formazan was found in most of syncytiotrophoblast (STr) and located in top of cells in severe PIH and IUGR placentae. In normal term placentae the blue formazan was found in STr and located in base of cells. The number of blue formazan was more than that of PIH and IUGR placentae. Endothelial cells of most capillaries of the terminal villi in severe PIH and IUGR placentae were found to be deposited with blue formazan, but in normal term pregnancy, blue formazan was found only on rare occasion. CONCLUSION: Distribution and localization of NOS in placentae of normal term pregnancy, severe PIH and IUGR cases and early villi are specific. The NOS activity of STr in severe PIH placentae and IUGR placentae are lower than that of normal term placentae. The distribution and localization of NOS within the STr in severe PIH placentae and IUGR placentae are different from those in normal term placentae. The low activity of NOS secreted by placenta may be relative to the pathogenesis of PIH and IUGR.     

Nitric oxide synthase activities in human myometrium and villous trophoblast throughout pregnancy

OBJECTIVE: To study the changes in nitric oxide synthase activities in human myometrium and trophoblast throughout pregnancy and around delivery. METHODS: Samples of villous trophoblast were collected from women undergoing elective cesarean delivery at term (n = 12) or voluntary termination of pregnancy in the first (n = 27) or second (n = 11) trimesters of pregnancy. Myometrial samples were obtained from nonpregnant women undergoing hysterectomy (n = 5) and pregnant women both before (n = 7) and after (n = 7) the onset of spontaneous labor at term. Nitric oxide synthase activity was quantified for homogenized samples using the L-citrulline assay in the presence and absence of calcium. RESULTS: The highest levels of nitric oxide synthase activity were found in first-trimester villi (range 2-29 nmol L-citrulline/minute/g protein), with a significant fall in activity in the third trimester (range 2-10 nmol L-citrulline/minute/g protein; P < .001 for both calcium-dependent and calcium-independent activity). Myometrial activities were relatively low compared with those in the trophoblast (0-2 nmol L-citrulline/minute/g protein), with no significant differences in calcium-dependent activities between subgroups. Myometrial calcium-independent activities were lower in pregnant than in nonpregnant women (P = .007), with those in labor having levels higher than those not in labor (P = .048). CONCLUSION: Levels of nitric oxide synthase activity are relatively high in villous trophoblast, particularly during the first trimester. Although the contribution to total nitric oxide production in the uterus by myometrial nitric oxide synthase appears to be relatively small, nitric oxide produced by the trophoblast may play a role in maintaining uterine quiescence by a paracrine effect. Further work is needed to test this hypothesis and explore other possible roles for trophoblast-derived nitric oxide in early pregnancy.     

Structural characteristics of term human fetal membranes: a novel zone of extreme morphological alteration within the rupture site

OBJECTIVE: To determine the structural characteristics of the rupture site of term fetal membranes (amniochorion and decidua) that rupture spontaneously after the onset of labour. DESIGN: Fourteen term fetal membranes were examined immediately after delivery at the light microscope level. Multiple samples were taken along the whole rupture site and long an axis between this site and placental edge. Morphometric analysis of the thickness of the constituent layers of the fetal membranes was performed. SETTING: Leicester Royal Infirmary Maternity Hospital. RESULTS: A restricted zone of extreme altered morphology, characterised by marked swelling and disruption of the connective tissue, thinning of the trophoblast layer and thinning or absence of decidua, was identified in the rupture site of all patients. Morphometric analysis of the thickness of membrane layers showed that these changes and the ratio between the thickness of the connective tissue layers and that of the trophoblast and decidua (termed fetal membrane morphometric index) were significant between the zone of extreme altered morphology and the rest of the membranes. CONCLUSIONS: The morphological features of the zone of extreme altered morphology suggests that it represents an area of structural weakness of the membranes. Since this zone did not include the whole length of the rupture site, it is likely that it was present before membrane rupture and was generated during pregnancy. We hypothesise that the zone of extreme altered morphology represents the site of initial rupture after which the tear is transmitted through the membranes to produce the rupture site. It is possible that if these changes become more extreme, then prelabour membrane rupture may occur. Further characterisation of this zone may help to understand the mechanism of its genesis and its role in predisposing the fetal membranes to rupture.     

Cytokine secretion by human fetal membranes, decidua and placenta at term

Cytokines such as monocyte chemotactic peptide-1 (MCP-1), interleukin-8 (IL-8), RANTES (Regulated on Activation and Normally T-cells Expressed and presumably Secreted) and interleukin-10 (IL-10) are thought to play pivotal roles in immune recognition, acceptance of the fetal allograft, maintenance of pregnancy and parturition. Their secretion and regulation within the third trimester uterus is, however, less well defined. We therefore investigated the release of these cytokines by third trimester amnion, chorion, placenta and decidua, and studied the influence of prostaglandin E2 (PGE2) infusion on their release in a dynamic placental cotyledon perfusion system. MCP-1 was released predominately by the chorion (78.2 +/- 7.3 pg/mg wet tissue weight; mean +/- SEM), decidua (112.4 +/- 5.2 pg/mg) and placenta (101.8 +/- 5.0 pg/mg) with low amounts from the amnion (1.3 +/- 0.4 pg/mg). High concentrations of IL-8 were released by the amnion (39.9 +/- 5.3 pg/mg), chorion (52.8 +/- 1.9 pg/mg), decidua (42.2 +/- 1.5 pg/mg) and placenta (45 +/- 1.3 pg/mg). Release of RANTES was not detectable from the amnion but was detected in moderate amounts from the chorion (6.0 +/- 1.2 pg/mg), decidua (15.2 +/- 1.4 pg/mg) and placenta (26.9 +/- 1.6 pg/mg). Low concentrations of IL-10 were secreted by the chorion (6.8 +/- 0.8 pg/mg), decidua (9.0 +/- 0.9 pg/mg) and placenta (3.3 +/- 0.3 pg/mg) with none detectable from the amnion. MCP-1, IL-8, RANTES and IL-10 were all released by perfused placental cotyledons. PGE2 stimulated release of MCP-1, IL-8 and IL-10 into the maternal and of MCP-1 and IL-8 into the fetal circulation of the placenta but had no effect on RANTES release. It is suggested that MCP-1 and IL-8 may be involved in the inflammatory process of parturition and IL-10 in the protection of the fetal allograft. In addition, PGE2 may have an important immunomodulatory role within the uterus at term.     

Total wrist fusion. A functional assessment

OBJECTIVE: Pregnancy induced hypertension has been shown to be associated with a normal or low activity of the maternal circulating renin-angiotensin system (RAS) but little is known of the local RAS in placenta and fetal membranes. The present study attempts to determine, at full term of human preeclamptic pregnancies, the activity of the chorioplacental renin-angiotensin system. PATIENTS AND MEASUREMENTS: We analysed the concentrations of active renin, prorenin, angiotensin converting enzyme (ACE) and angiotensin II in homogenates of human placenta and fetal membranes from preeclamptic patients at full term pregnancy. The values of renin, ACE and angiotensin II found in the patients with moderate preeclampsia (gestosis index 0-1) (n = 10) were compared with those of normal pregnant women (n = 8). RESULTS: Our experiments showed that in preeclamptic pregnancies, the chorion membrane contained the highest concentrations of active renin (2905 +/- 152 pg/g, mean +/- SD), prorenin (21,315 +/- 2849 pg/g) and ACE (1258 +/- 302 U/g) whereas the placenta had more angiotensin II than the chorion and amnion (741 +/- 45 vs 456 +/- 40 and 428 +/- 64 pg/g, respectively). In the placenta, as in the fetal membranes, no significant difference was found in the levels of active renin, ACE or angiotensin II between hypertensive patients and normal subjects but a slightly lower level of chorionic prorenin (P < 0.05) was observed in pregnancy induced hypertension. CONCLUSION: These findings indicate that in moderate preeclampsia (gestosis index 0-1), the activity of the renin-angiotensin system in term human placenta and fetal membranes remains essentially normal.     

Nitric oxide synthase activity in the gravid rat uterus decreases a day before the onset of parturition

OBJECTIVE: Our purpose was to determine the timing, tissue location, and isoform of the uterine nitric oxide synthase activity decrease at term in gravid rat uteri. STUDY DESIGN: Nitric oxide synthase specific activity was assayed in rat uteri 11 through 22 days' gestation by the difference in radiolabeled arginine to citrulline conversion with and without the cofactor reduced nicotinamide adenine dinucleotide phosphate. Nitric oxide synthase isoform was assessed by calcium sensitivity and subcellular location. RESULTS: Rat uterine nitric oxide synthase activity decreased between days 15 and 21 of gestation but did not decrease further at term (day 22), before and after the onset of labor. Decidual nitric oxide synthase activity exceeded the myometrial activity at 15 days' gestation, but then the two were equal at 18 through 22 days' gestation. The nitric oxide synthase activity was calcium insensitive except for half the decidual cytosolic activity on day 15. CONCLUSION: The decrease in pregnant rat uterine nitric oxide synthase activity coincides with the preparation of the uterus for parturition rather than the final activation of labor.     

Gestational changes in the levels of transforming growth factor-beta1 (TGFbeta1) and TGFbeta receptor types I and II in the human myometrium

As term approaches, a number of key proteins [contraction-associated proteins (CAPs)] are expressed within the human myometrium that are essential for the activation of powerful coordinated contractions during labor. The nature of the signals that switch on the synthesis of CAPs in vivo is not known. The ryanodine-sensitive intracellular Ca2+ release channel (RyR2) is a CAP whose expression in vitro is activated by transforming growth factor-beta (TGFbeta). The present experiments were performed to determine whether TGFbeta and TGFbeta receptors are present in the human myometrium at term and to explore the idea that they might form part of a signaling system in vivo. TGFbeta receptor types I and II, but not III, were demonstrated in myometrial smooth muscle in tissue taken from nonpregnant, pregnant nonlaboring, and spontaneous laboring women. Western blotting was used subsequently to determine the relative expression of TGFbeta receptor types I and II. Using nonpregnant myometrium as a baseline control the levels of expression of receptor types I and II were significantly increased by 168 +/- 19% (n = 6) and 162 +/- 22% (n = 7) in pregnant nonlaboring myometrium. In spontaneous laboring myometrium the levels of TGFbeta receptor type I and II expression were 93 +/- 12% (n = 6) and 85 +/- 11% (n = 7), respectively, compared to nonpregnant control values and were significantly lower than levels in pregnant nonlaboring tissues. The total TGFbeta1 levels in the myometrial tissues were 334 +/- 10, 534 +/- 73, and 674 +/- 106 pg/g tissue wet wt in nonpregnant, pregnant nonlaboring, and spontaneous laboring myometrium (n = 3 in each group), respectively. Thus, the TGFbeta signaling system appears to be up-regulated in the myometrium before the onset of parturition. The apparent loss of receptors in the spontaneous laboring samples in the presence of elevated total levels of TGFbeta may be indicative of agonist-induced receptor down-regulation. These observations support the idea that cytokines, in particular TGFbeta1, may play a role in the normal processes that prepare the myometrium for parturition at term.     

Maternal dietary protein deficiency decreases nitric oxide synthase and ornithine decarboxylase activities in placenta and endometrium of pigs during early gestation

Little is known about the mechanism responsible for retarded placental and fetal growth induced by maternal dietary protein malnutrition. On the basis of the recent finding that nitric oxide (NO) and polyamines (products of L-arginine) play an important role in embryonic and placental development, the present study was designed to determine whether protein deficiency decreases placental and endometrial activities of NO synthase (NOS) and ornithine decarboxylase (ODC) (the first and key regulatory enzyme in polyamine synthesis). Primiparous gilts selected genetically for low or high plasma total cholesterol concentrations (low line and high line, respectively) were mated and then fed 1.8 kg/d of isocaloric diets containing 13% or 0.5% crude protein. At d 40 or 60 of gestation, they were hysterectomized, and placenta and endometrium were obtained for incubations, NOS and ODC assays, and measurements of free amino acids and polyamines. Maternal dietary protein restriction decreased arginine and ornithine concentrations, constitutive and inducible NOS activities and NO production, as well as ODC activity and polyamine concentrations in placenta and endometrium of both lines of gilts. Placental NO synthase activity and NO generation were lower in high line gilts than in low line gilts. ODC activities and polyamine concentrations in placenta and endometrium were decreased at d 60 compared with d 40 of gestation. These changes in placental and endometrial synthesis of NO and polyamines during early gestation may be a mechanism responsible for reduced placental and fetal growth in protein-deficient gilts and for altered conceptus development in high line gilts.     

The effects of 3,4-dihydroxyacetophynone on the activity of nitric oxide synthetase in placental vascular endothelial cells and smooth muscle cells and on the level of endothelin-1 in plasma from pregnancy-induced hypertension patients

OBJECTIVE: To observe the effects of 3,4-dihydroxyacetophynone (DHAP), one of the constituents of a traditional Chinese herbal medicine, on the activities of endothelial nitric oxide synthetase (NOS) in vascular endothelial cells (VEC) and vascular smooth muscle cells (VSMC) of placenta and the level of endothelin-1 (ET-1) in the plasma from PIH patients. METHOD: 22 nulliparous PIH patients were randomly divided into PIH group and DHAP treatment group. Each patients in DHAP group received intravenous administration of DHAP (160-240 mg/d). Blood samples were collected before the administration of DHAP and (or) before cesarean section. The placenta were assayed for nitric oxide synthase activity using histochemical analysis; the concentration of ET in plasma was measured by radioimmunoassays. 10 normal pregnant women or 10 nonpregnant women were served as controls. RESULTS: In normal pregnant controls, NOS activity was much higher than that in the PIH group; in DHAP group, there was some recovery of NOS activity after DHAP treatment. The concentration of ET was higher in PIH group than that of normal pregnant controls, but it decreased significantly after DHAP therapy (P < 0.05, vs PIH group or before DHAP therapy). CONCLUSION: This study indicates that DHAP is effective in the treatment of PIH and its mechanism of action may be due to the adjustment of NO/ET imbalance in PIH patients.     

Renin-like immunoreactivity in human placenta and fetal membranes

Five antibodies that stained renin in the kidney were used to investigate the presence of renin in human placenta and fetal membranes. Despite a large number of experimental approaches to enhance penetration of the immunoglobulins, only two of them showed immunostaining in placenta and fetal membranes. Staining was found in placental syncytiotrophoblast, the amnionic epithelium overlying the placenta, and in glandular epithelial cells present in the decidua adhering to the fetal membranes. It was most consistent, however, in a small infiltrating cell type dispersed through the fetoplacental layers. The two antibodies that revealed immunostaining in all preparations showed high affinity cross-reactivity with cathepsin D. Among other, less plausible, explanations, this raises the possibility that the bulk of 'renin' found in placenta and fetal membranes is not identical to renal renin, but may be cathepsin D or a substance related to both cathepsin D and renin.     

Type II phospholipase A2 in human gestational tissues: extractable immuno- and enzymatic activity in fetal membranes

In this study, we have established the presence of immunoreactive (ir) Type II PLA2 in human amnion and choriodecidua obtained from women at term prior to the onset of labour. The content of irType II PLA2 present in 1 M NaCl extracts of choriodecidua and amnion averaged 3.5 +/- 3.1 and 10.6 +/- 5.2 ng/mg tissue protein (n = 3), respectively. PLA2 enzymatic activity present in the same tissues averaged 1.3 +/- 0.2 and 1.9 +/- 0.7 nmol phosphatidylethanolamine (PE) hydrolysed/mg tissue protein per h (n = 3), respectively. To allow intra-patient comparison of the relative distribution in gestational tissues, irType II PLA2 and PLA2 enzymatic activity was also determined in placenta obtained from the same group of women, and averaged 26.0 +/- 7.0 ng/mg tissue protein and 3.5 +/- 1.0 nmol PE hydrolysed/mg protein per h (n = 3), respectively. As has been previously reported for human placenta, the recovery of Type II PLA2 and PLA2 enzymatic activity from amnion and choriodecidua was increased between 16- and 25-fold when tissues were homogenized in high-ionic strength media (i.e., 10% (w/v) ammonium sulphate or 1 M NaCl) compared with that recovered when tissues were homogenized in low-ionic strength media (i.e., 0.32 M sucrose-20 mM Hepes). The data obtained represent the first quantitative estimates of immunoreactive Type II PLA2 in human amnion and choriodecidua, and support the conclusion that previous analyses of the PLA2 enzymatic activity present in gestational tissues have essentially excluded the contribution made by this PLA2 isozyme to net enzymatic activity. We suggest that this isozyme represents a major component of the PLA2 enzymatic activity present in human gestational tissues at term and that it contributes significantly to the phospholipid metabolism and arachidonic acid release which occurs during late pregnancy and at the time of labour.     

Expression of laminin and nidogen genes during the postimplantation development of the mouse placenta

The expression patterns of laminin A, B1, B2, and nidogen genes were identified by in situ hybridization in postimplantation mouse extraembryonic tissues and maternal decidua during the period when the chorioallantoic placenta is established. Laminin and nidogen genes were not coordinately expressed either in the decidua or in trophoblast cells, indicating that these genes are regulated independently in these cell types during the establishment of the placenta. Laminin A mRNA was absent from the decidua except in the outer layer of cells adjacent to the myometrium and in the central decidual zone adjacent to the remnant of the uterine epithelium on Day 9. At this stage laminin B1, B2, and nidogen genes were strongly expressed in these cells and also in other regions of the decidua. Laminin B1 mRNA was present at higher levels in the decidua capsularis than in the decidua basalis, while nidogen mRNA showed highest expression in the decidua basalis. Laminin B2 mRNA was produced uniformly throughout the decidua at very high levels, suggesting that laminin B2 chains may be an important component of the decidual matrix. By Day 11, the nidogen gene was expressed only in endothelial cells lining the maternal blood spaces within the decidua. Laminin B1 and nidogen mRNAs were found at high levels within trophoblast giant cells at all stages, while laminin A mRNA was detected in trophoblast giant cells at later stages and laminin B2 mRNA was not produced in high levels by these cells. The patterns of gene expression show a very high degree of regional specialization, suggesting that the extracellular matrices in different regions of the decidua and extraembryonic membranes are likely to be composed of quite different ratios of laminin and nidogen polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)