Tissue inhibitor of metalloproteinases: serum levels during pregnancy and labor, term and preterm

OBJECTIVE

To determine the levels in serum of tissue inhibitor of metalloproteinases (TIMP) in pregnancy and to examine the possibility of a time course in relation to parturition, both term and preterm.

METHODS

Serum tissue inhibitor of metalloproteinases was measured using an enzyme-linked immunosorbent assay. A cross-sectional study was conducted in 333 women during pregnancy, labor, and the postpartum period and in 27 nonpregnant volunteers. Longitudinal data were obtained from 22 women who provided a sample at term, during labor, and in the postpartum period.

RESULTS

In uncomplicated pregnancies, serum TIMP levels were low from the onset of pregnancy until 37 weeks' gestation, in comparison to levels in nonpregnant women (P < .001). During the final weeks of pregnancy, levels rose and at 37-42 weeks were similar to nonpregnant levels. The levels did not change with the onset of labor. Serum concentrations of TIMP obtained during preterm labor were elevated compared to a control group of patients at a similar gestation who subsequently delivered at term (P < .01). Serum TIMP levels were significantly higher during the postpartum period than at all other times (P < .001).

CONCLUSIONS

Changes in serum TIMP levels during and after pregnancy may parallel the remodeling of the extracellular matrix that takes place throughout this period. Further work is necessary to evaluate the prognostic value of TIMP for preterm labor.

Tissue collagenase: serum levels during pregnancy and parturition

Serum levels of tissue collagenase, matrix metalloproteinase-1, were measured in both longitudinal and cross-sectional studies, in 332 pregnant women and 27 non-pregnant volunteers. The enzyme-linked immunosorbent assay (ELISA) used is the first described to measure collagenase in serum directly, is specific, and is rapid and reproducible. Levels were determined throughout pregnancy, during term and preterm labour, and in the post-partum period. Serum tissue collagenase levels were elevated in pregnancy (P < 0.001). There was no difference between levels of serum collagenase prior to labour at term and those observed during labour. Similarly, there was no significant difference in levels obtained during preterm labour and those at a similar gestation in women who subsequently delivered at term. No significant decrease in levels had occurred by the 4th post-partum day. In view of these findings of unaltered matrix metalloproteinase-1 levels in association with labour, previous reports of raised serum collagenase activity in association with the onset of spontaneous labour, at term and preterm gestation periods, may be due to increased neutrophil collagenase activity.

Expression of c-kit and kit ligand at the human maternofetal interface

Kit ligand, or stem cell factor, is a recently identified growth factor, which binds to and activates the c-kit proto-oncogene, and which has been shown to act synergistically with other haematopoietic growth factors in the bone marrow. We have previously shown that several isoforms of kit ligand, which arise due to alternative splicing, are expressed in human placenta. In order to elucidate the role of c-kit and its ligand during human placental development we have investigated the expression of c-kit and kit ligand in human first trimester and term placenta as well as in pregnant and non-pregnant endometrium, by immunocytochemistry and flow cytometric analysis. In non-pregnant endometrium no expression of kit ligand was seen. By contrast, in first trimester decidua, kit ligand was strongly expressed by the arterial media of maternal blood vessels. Kit ligand was also expressed throughout pregnancy by invasive fetal extravillous trophoblast, and by fetal fibroblasts within the placental villi. c-kit was found to be expressed on Hofbauer cells within the chorionic villi, and by decidual macrophages at all stages in pregnancy. c-kit was also detected on the small CD56dim subset of uterine large granular lymphocytes which form the major leukocyte population in human first trimester decidua. Our results suggest that kit ligand may be involved in the regulation of fetal macrophages, and in particular in signalling between invading extravillous trophoblast which expresses kit ligand, and maternal leukocytes bearing the c-kit receptor.

Estimating temporary populations

The difficulty of tracking temporary short-term population movements (commuting, seasonal visitation, convention and business travel) is examined, with a focus on Hawaiian statistician Robert Schmitt's work. The author finds that "Schmitt's contributions toward a methodology for estimating daytime populations were important because this approach utilized data sources that were widely available for small areas on at least an annual basis. Consequently, this approach could be used for frequent updates of the estimates, for many areas and at relatively little cost.... The major drawback of the approach is the lack of solid data on temporary residents to serve as larger-area control totals and as a historical base for small-area estimates." The geographical focus is on the United States, particularly Hawaii.

Basic FGF activates phospholipase D in endothelial cells in the absence of inositol-lipid hydrolysis

In the absence of inositol-lipid hydrolysis, mitogenic concentrations of basic fibroblast growth factor (bFGF) stimulated phosphatidylbutanol formation in the presence of butan-1-ol in [3H]myristate-labeled human umbilical vascular endothelial (HUVE) cells, indicating that the fibroblast growth factor receptor was able to couple to the activation of phospholipase D (PLD). The ability of bFGF and 12-O-tetradecanoylphorbol-13-acetate (TPA) to stimulate PLD activity was completely abolished in cells pretreated with 400 nM TPA for 48 h to downregulate protein kinase C (PKC). bFGF-stimulated PLD activity was inhibited by genistein (5 microM; P < 0.02) and the PKC inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7, 5 microM; P < 0.001) as well as by the removal of calcium from extracellular environment. bFGF induced DNA synthesis in a dose-dependent manner, and pretreatment of cells with H-7 inhibited the mitogenic activity of bFGF. These results indicate that activation of PKC is responsible for bFGF-induced PLD activation and the mitogenic activity of bFGF in HUVE cells. A coupled PLD/3-sn-phosphatidate phosphohydrolase pathway may play a role in the regulation of endothelial cell proliferation.

Colocalization of acidic and basic fibroblast growth factor (FGF) in human placenta and the cellular effects of bFGF in trophoblast cell line JEG-3

The placenta undergoes extensive angiogenesis and cellular proliferation to establish adequate blood supply to the fetus. The aim of this study was to compare and contrast the immunolocalization of acidic and basic fibroblast growth factor (FGF) in both first trimester and term placenta and gestational decidua. Human choriocarcinoma cell line JEG-3 were employed as a model of cytotrophoblast and the effect of basic FGF on cell proliferation and phospholipase C and D activation investigated. Basic FGF-immunoreactivity (IR) was detected in or around cytotrophoblast cells and in extravillous trophoblast in first trimester placenta by immunohistochemistry using primary polyclonal rabbit antibodies. Identical staining patterns were produced by acidic FGF antibodies indicating colocalization of acidic FGF and basic FGF. At term, weaker and more diffuse staining was seen in the syncytiotrophoblast surrounding the placenta villi and strong staining was present in the smooth muscle cells of mid and large size placental vessels and in some endothelial cells. Endothelial cells and extravillous trophoblast stained strongly within the decidua at first trimester, whereas the glandular epithelium was weakly stained. Basic FGF induced [3H]thymidine incorporation in JEG-3 cells in a dose dependent manner and caused an increase in inosital phosphate accumulation in cells pre-labelled with myo-[3H]inosital at similar concentrations, suggesting a role of phospholipase C in JEG-3 cell proliferation. However, basic FGF failed to stimulate phospholipase D activity in cells pre-labelled with [3H]myristic acid. The detection of acid FGF and basic FGF on both maternal and fetal side of the placenta during early pregnancy suggests a role for FGF in angiogenesis, whereas localisation of the growth factor at term, when extensive angiogenesis has diminished, would indicate that FGF may be associated with more differentiated functions of the trophoblast. The nuclear localization of basic FGF in dividing but not non-dividing placental cells together with the effect of basic FGF on JEF-3 cells, strongly supports a role for basic FGF in cytotrophoblast proliferation in vivo.

The effects of potassium channel openers on isolated pregnant human myometrium before and after the onset of labor: potential for tocolysis

OBJECTIVE

Our purpose was to investigate the effects and pharmacologic properties of potassium channel openers in isolated pregnant human myometrium.

STUDY DESIGN

Biopsy specimens of myometrium obtained from 67 women during pregnancy and labor were used for isometric recording under physiologic conditions.

RESULTS

Levcromakalim and pinacidil, two prototype potassium channel openers, are potent inhibitors of spontaneous and induced (0.5 nmol/L oxytocin and 10 mumol/L phenylephrine) contractions in isolated human pregnant myometrium, obtained before and after the onset of labor. The sulfonylurea glibenclamide is an apparent competitive antagonist of this inhibition. No antagonism was observed with the sulfonylurea tolbutamide. Both potassium channel openers significantly inhibited contractility evoked by low (10 and 20 mmol/L) but not high (40 and 80 mmol/L) concentrations of extracellular potassium chloride.

CONCLUSION

These findings suggest that the relaxant ability of levcromakalim and pinacidil in human pregnant myometrium is because of potassium channel activation. This introduces a potential new approach for tocolysis.

Expression of mRNA for vascular endothelial growth factor in human placenta

Implantation and growth of the placenta requires extensive angiogenesis to establish the vascular structures involved in exchange. Failure to establish adequate blood supply to the fetus may have serious clinical consequences such as intrauterine growth retardation. Vascular endothelial cell growth factor (VEGF) is a recently identified growth factor with significant angiogenic properties. We have demonstrated the presence of four species of mRNA encoding VEGF in both first trimester and term placenta. In situ hybridization was used to localize the sites of expression of VEGF mRNA in these tissues. VEGF expression was seen in villous trophoblast in the first trimester and in extravillous trophoblast at term, and in both fetal macrophages within the villi and maternal macrophages in the decidua. Glandular epithelium in maternal decidua also expressed VEGF mRNA. The strongest site of expression was in maternal macrophages adjacent to Nitabuch's stria, a zone of necrosis at the site of implantation. This complex pattern of expression suggests that VEGF is involved in angiogenesis on both maternal and fetal sides of the placenta and that macrophages are the primary source of VEGF. However, VEGF may also play a role in term placenta, when extensive angiogenesis has diminished, possibly regulating vascular permeability.

Evaluation of aspects of the protection afforded to sheep immunised with a gut membrane protein of Haemonchus contortus

Experiments were undertaken to evaluate the type of protection conferred against Haemonchus contortus by immunising sheep with H11, a 'hidden' integral gut membrane protein isolated from this parasite. A serial kill experiment showed that worms began to be lost from immunised lambs between seven and 14 days after challenge with a single dose of larvae and adult female worms were more susceptible than male worms. Seven-day-old juveniles survived immunisation even though their intestinal cells became coated with sheep antibody. Immunisation was equally effective against both benzimidazole-resistant and susceptible strains of H contortus. When immunised lambs were subjected to a trickle infection, they were largely protected against the anaemia and egg output observed in the challenge controls. Moreover, they grew as fast and as efficiently as uninfected lambs fed on the same high protein diet and acquired a natural immunity during the course of the trickle infection.

Alternatively spliced mRNAs for human endothelin-2 and their tissue distribution

The cDNA for Endothelin-2 (ET-2) has been previously cloned and characterised; however, ET-2 remains the least studied of the endothelin isopeptides and little is known of its function and location. In the present study reverse transcriptase-polymerase chain reaction revealed the presence of seven alternatively spliced mRNA variants encoding ET-2, with a specific pattern of distribution in various human tissues. Computer alignment and analysis of the DNA sequences demonstrated alternative splicing of five exons of 52, 169, 123, 99 and 174 base pairs, in the carboxy terminal region of the mRNA encoding preproET-2. This region contains sites for the post-transcriptional processing of preproET-2 into mature ET-2, therefore we postulate that post-transcriptional processing may be disrupted or altered in these variants.

Identification and localization of alternately spliced mRNAs for vascular endothelial growth factor in human uterus and estrogen regulation in endometrial carcinoma cell lines

Repair of human endometrium after menstruation and preparation of the endometrium for implantation involves profound angiogenic changes. Vascular endothelial cell growth factor (VEGF) is a recently identified growth factor with significant angiogenic properties. Four species of mRNA encoding VEGFs were identified in human endometrium and myometrium. All species were present throughout the menstrual cycle. Two species, VEGF165 and VEGF121, were present in peripheral leukocytes, indicating tissue-specific splicing of the two other VEGF transcripts. In situ hybridization of mRNA encoding VEGF was not restricted to vascular smooth muscle but was present in epithelial and stromal cells of endometrium throughout the cycle, and the distribution changed during the course of the cycle. All four species of VEGF were expressed by the endometrial carcinoma cell lines Ishikawa, HEC 1-A, and HEC 1-B. Estradiol increased steady-state levels of mRNA encoding VEGF in a dose- and time-dependent manner in HEC 1-A cells. Conditioned medium from these cells possessed angiogenic activity that was depleted by passage through a heparin affinity column. None of the cell lines demonstrated mRNA for acidic or basic fibroblast growth factor (FGF), despite previous reports of the identification of immunoreactive basic FGF in HEC 1-A and HEC 1-B cells. These findings show that VEGFs, not FGFs, are the principal angiogenic growth factors secreted by these cells and that human endometrium expresses a secreted angiogenic growth factor whose site of expression changes during the menstrual cycle.

Perimenstrual complaints in women complaining of PMS, menorrhagia, and dysmenorrhea: toward a dismantling of the premenstrual syndrome

Four groups of women were compared in terms of their perimenstrual symptoms, reported menstrual blood loss and period pain, and neuroticism scores: three patient groups were referred to a Gynaecology Outpatient Clinic because of menorrhagia (N = 101), PMS (N = 104), dysmenorrhea (N = 56), and a control group (N = 105). The three patient groups showed considerable overlap in a number of symptoms. This has led us to postulate three factors contributing to perimenstrual complaints: a) a 'timing factor' linked to the ovarian cycle; b) a 'menstruation factor,' associated with the buildup of the endometrium and its shedding; and c) a 'vulnerability factor,' one aspect of which, 'neuroticism,' was measured in this study. Depressive symptoms, which were the most important in leading women to seek help for their PMS, were related to all three factors. Depressive mood changes seemed to be linked to the 'timing factor' but were noticeably worse and more prolonged in women with high neuroticism, heavy bleeding, or severe pain. One premenstrual symptom, food craving, was of considerable interest. This was weakly related to neuroticism, not apparently affected by the 'menstruation factor' and differed in severity between those in the PMS group and the other three groups. It is potentially relevant that both carbohydrate craving and depression are linked to serotonergic changes in the brain, which may prove to be particularly marked in the late luteal phase.

Properties of large-conductance K+ channels in human myometrium during pregnancy and labour

The conversion of the electrically silent pregnant uterus to highly excitable at term represents a dramatic physiological event which is poorly understood. Here we provide the first description, from single-channel recordings, of a large conductance (212 pS) calcium-activated potassium channel (BKCa) in human pregnant myometrium which, in labour tissue, is either absent or has been considerably altered in its physiological and pharmacological properties. In the latter, the K+ channels have an identical conductance (221 pS) and K+ selectivity to BKCa channels but exhibit no Ca2+ or voltage sensitivity. We have termed these BK channels. Furthermore, the activity of the BKCa channel from pregnant tissue is inhibited by internal application of Ba2+ but not tetraethylammonium (TEA), whereas the activity of the BK channel is sensitive to internal TEA but not Ba2+. The role of the BKCa channel may be to suppress myometrial activity during gestation whereas BK channel activity may be important in providing a Ca(2+)-independent K+ conductance which would allow cytoplasmic Ca2+ levels to rise without activating a counteracting Ca(2+)-dependent outward current, normally provided by the BKCa channels which, by its very nature, would tend to oppose depolarization. The findings suggest that K+ channels may have an important role in determining the functional activity of the myometrium.

Immunohistochemical localization of acidic and basic fibroblast growth factors in normal human endometrium and endometriosis and the detection of their mRNA by polymerase chain reaction

Growth factors play a role in the cyclical growth and vascularization of normal endometrium. Abnormal endometrial proliferation and neovascularization may result in endometriosis. This study determines the presence and localization of acidic and basic fibroblast growth factors (aFGF and bFGF respectively) in endometrium of normal women, and in normal and ectopic endometrium of women with endometriosis. Endometrium was obtained at curettage or hysterectomy for benign disease, or laparoscopy for endometriosis. aFGF- and bFGF-immunoreactivity was detected at different phases of the menstrual cycle by immunohistochemistry using primary polyclonal rabbit antibodies. Expression of mRNA for aFGF and bFGF was determined in normal endometrium by nested reverse transcriptase polymerase chain reaction (RT-PCR). aFGF- and bFGF-immunoreactivity were both detected in endometrium from normal women, and in normal and ectopic endometrium of women with endometriosis. The pattern of staining with the two different FGFs was the same: immunoreactivity was predominantly confined to glandular epithelial cells and did not change throughout the menstrual cycle. Little or only light staining was seen in stromal cells and myometrium, and the pattern of staining did not differ between endometriotic and normal tissue. The presence of mRNA for aFGF and bFGF was demonstrated in normal endometrium. The detection of aFGF and bFGF mRNA in normal endometrium and aFGF- and bFGF-immunoreactivity in normal and endometriotic tissues suggests that these peptides may play a role in the proliferation and angiogenesis of normal and ectopic human endometrium.

Endothelin-2 mRNA splice variants detected by RT-PCR in cultured human vascular smooth muscle and endothelial cells

Our aim was to examine the hypothesis that vascular smooth-muscle cells (VSMCs) express only ETA mRNA and endothelial cells express only ETB mRNA and to determine which ET mRNA isoforms are expressed in these cell cultures. Using the reverse transcriptase polymerase chain reaction, we were able to detect ETB, ET-1 and splice variant ET-2 mRNA in cultured human umbilical vein endothelial cells (HUVECs) and ETA and splice variant ET-2 mRNA in cultured aortic smooth-muscle cells. The presence of ET-2 mRNA in cultured VSMCs has not been previously reported. These results agree with the hypothesis that ET-1 may be released from vascular endothelial cells to act predominantly on ETA receptors on VSMCs to stimulate contraction of the underlying smooth-muscle cells, and that endothelium-derived relaxing factor release may be mediated predominantly via the ETB receptors on HUVECs. The role of ET-2 expression from HUVECs and VSMCs is less clear.

Presence of messenger ribonucleic acid for endothelin-1, endothelin-2, and endothelin-3 in human endometrium and a change in the ratio of ETA and ETB receptor subtype across the menstrual cycle

The aim of the present study was to determine whether mRNA for the three endothelin peptides (endothelin-1, endothelin-2, and endothelin-3) and the two known receptor subtypes (ETA and ETB) was present in human endometrium at different stages of the menstrual cycle (menstrual, early and mid-proliferative, and early, mid-, and late secretory). Endometrium was obtained from women undergoing surgery for benign disease, and total RNA was extracted using a guanidinium isothiocyanate method. mRNA for endothelin peptide and receptor was detected using the reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers. mRNA for endothelin-1, endothelin-2, and endothelin-3 was demonstrated throughout the menstrual cycle, and three splice variants of mRNA encoding endothelin-3 were found in all samples. The ratio of ETA to ETB receptor mRNA was found to change throughout the menstrual cycle. In the proliferative phase, amplified cDNA product was almost exclusively confined to the ETA receptor, whereas an increase in the amplified product of the ETB receptor cDNA was seen in the secretory and menstrual phases. These studies show that mRNA for endothelin-1, endothelin-2, and endothelin-3 is present in human endometrium at all stages of the menstrual cycle and suggest that different physiological actions of the endothelin peptides may be mediated through changes in the ratio of the ETA and ETB receptor subtypes.

Activation of phospholipase A2 and phospholipase C by endothelin-1 in human endometrium

Human endometrium contains specific binding sites for iodinated endothelin (ET)-1, ET-2 and ET-3, and ET-1 stimulates prostaglandin (PG) F2 alpha synthesis from explants of proliferative endometrium in short-term culture. This study has investigated the cellular responses of normal proliferative endometrium to ET-1. Radioimmunoassay was used to measure PG release and Dowex anion-exchange column chromatography was utilized to assess the accumulation of inositol phosphates. Endothelin-1 induced a significant increase in PGF2 alpha release (basal median: 1465 pg/mg per 60 min (range: 541-3935 pg/mg per 60 min); ET-1-stimulated: 1813 pg/mg per 60 min (1021-5714 pg/mg per 60 min); P < 0.04 using Wilcoxon signed rank test). The effect of ET-1 was attenuated in the presence of the phospholipase A2 inhibitor quinacrine. Endothelin-1 induced a rapid, transient and concentration-dependent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), measured by the accumulation of tritiated inositol phosphates. Following a 1-min stimulation with ET-1 (100 nmol/l), [3H]inositol mono-, bis- and trisphosphate fractions increased from median values of 490.0 d.p.m./mg dry wt (range: 348.0-807.0 d.p.m./mg dry wt), 120.0 d.p.m./mg dry wt (93.6-144.1 d.p.m./mg dry wt) and 67.0 d.p.m./mg dry wt (54.2-85.0 d.p.m./mg dry wt) to 939.0 d.p.m./mg dry wt (635.9-1596.0 d.p.m./mg dry wt; P < 0.03), 145.0 d.p.m./mg dry wt (127.0-293.9 d.p.m./mg dry wt; P < 0.05) and 146.0 d.p.m./mg dry wt (77.5-187.0 d.p.m./mg dry wt; P < 0.03) respectively. These results suggest that ET-1 activates the phospholipase A2 and PtdIns(4,5)P2-specific phospholipase C in human proliferative endometrium, resulting in the generation of PGF2 alpha and second messengers respectively which are pivotal to endometrial function.

The effect of progesterone and human interferon alpha-2 on the release of PGF2 alpha and PGE from epithelial cells of human proliferative endometrium

Progesterone and interferon-like trophoblastic proteins modulate prostaglandin (PG) synthesis from endometrium in early ovine and bovine pregnancy. Enriched epithelial cells were prepared from human endometrium removed in the proliferative phase of menstrual cycle (n = 8). Progesterone at a concentration of 1 microM suppressed PGE release from the cells during the first 24 hours in culture. After 48 hours in culture progesterone at a dose of 100 nM and 1 microM suppressed both the release of PGF2 alpha and PGE from the cells and this suppression was maintained for a further two days. Addition of exogenous 30 microM arachidonic acid (AA) abolished this effect of progesterone on both PGF2 alpha and PGE release. Interferon alpha-2 did not suppress the basal release of PGF2 alpha nor PGE. In the presence of progesterone, interferon alpha-2 attenuated the progesterone mediated suppression of PGF2 alpha but not PGE release from endometrial cells. These findings suggest that progesterone suppresses the basal release of PGs from human endometrium, but unlike the sheep, interferon alpha-2 does not exert this action on human endometrium.

Evaluating the forecast accuracy and bias of alternative population projections for states

"A common perception among producers (and users) of population projections is that complex and/or sophisticated techniques produce more accurate forecasts than simple and/or naive techniques. In this paper we test the validity of that perception by evaluating the forecast accuracy and bias of eight commonly used projection techniques drawn from...four categories [trend extrapolation, ratio extrapolation, cohort-component, and structural]. Using data for [U.S.] state population projections from a number of different time periods, we find no evidence that complex and/or sophisticated techniques produce more accurate or less biased forecasts than simple, naive techniques."

Expression of messenger RNA for kit-ligand in human placenta: localization by in situ hybridization and identification of alternatively spliced variants

Kit-ligand is a novel polypeptide growth factor which binds and activates the c-kit protooncogene, a receptor tyrosine kinase. We used the technique of reverse transcription-polymerase chain reaction to demonstrate the expression of this growth factor in human placenta. In situ hybridization showed that kit-ligand mRNA is expressed in cytotrophoblast and syncytiotrophoblast cells in the placenta, and in fetally derived extravillous trophoblast cells which have invaded the maternal endometrium. Five species of mRNA encoding variants of kit-ligand were identified by nested reverse transcription-polymerase chain reaction. Cloning and sequencing indicate that these variants arise by alternative splicing of the kit-ligand transcript. One of these species, KL486, uses a novel splice site in exon 8. There is a different pattern of expression of the variants in amnion, chorion, trophoblast, and placenta, indicating tissue-specific control of splicing.

Eicosanoid synthesis and Helicobacter pylori associated gastritis: increase in leukotriene C4 generation associated with H. pylori colonization

The importance of pro-inflammatory leukotriene C4 in Helicobacter pylori (H. pylori) associated gastritis in man is unknown. Fresh gastric biopsy specimens from 28 dyspeptic patients were obtained: 10 showed normal antral histology with no evidence of H. pylori, the remaining 18 patients exhibited histological gastritis and were H. pylori positive as assessed by histology, culture and urease test. Twelve of these 18 patients received 240 mg twice daily colloidal bismuth subcitrate for four weeks before re-endoscopy. Gastric biopsies from H. pylori positive patients were incubated under basal and Ca(2+)-ionophore mediated conditions: Radioimmunoassay analysis of the supernatant showed basal release of prostaglandin E2 and leukotriene C4 was slightly but not significantly elevated in H. pylori positive mucosa. However in H. pylori positive mucosa there was an 85% increase in leukotriene C4 synthesis when biopsies were incubated with ionophore, compared to only 13% increase in H. pylori negative mucosa (p less than 0.02). After eradication of H. pylori by colloidal bismuth subcitrate, there was a clearance of inflammatory cell infiltrate as assessed by histology and a significant reduction in ionophore-mediated leukotriene C4 formation compared with before treatment (p less than 0.02). These results suggest that H. pylori gastritis is associated with increased capacity to generate leukotriene C4, which may amplify the damaging effects of the bacteria on gastric mucosa.

Platelet-activating factor stimulates phospholipase C activity in human endometrium

Human preimplantation embryos secrete platelet-activating factor (PAF), which stimulates prostaglandin E2 synthesis from secretory endometrium. This study investigated the action of PAF on phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-specific phospholipase C activity in human endometrium. Slices of normal endometrium were incubated with 5 microCi/ml myo-[2-3H] inositol for 3 h at 37 degrees C in 95% O2 and 5% CO2 to label tissue phosphoinositides. Inositol phosphates were extracted using trichloroacetic acid precipitation and diethylether neutralization and production was measured using Dowex 1-X8 anion-exchange column chromatography. PAF induced rapid and concentration-dependent accumulation of inositol phosphates (IP) from secretory endometrium, but had no effect on endometrium removed in the proliferative phase of the menstrual cycle. The IP3 fraction was significantly elevated from a median value of 14.0 c.p.m. mg-1 dry wt [range: 8-41 c.p.m. mg-1 dry wt] to 28.0 c.p.m. mg-1 dry wt [range: 11-87 c.p.m. mg-1 dry wt, P less than 0.002] following 1 min exposure of secretory endometrium to PAF-acether, in the presence of 10 mM LiCl. PAF-induced hydrolysis of PtdIns(4,5)P2 was inhibited by the specific PAF receptor antagonist WEB 2086, in a dose-dependent manner (P less than 0.02), indicating that in human endometrium PtdIns(4,5)P2 hydrolysis is mediated via a PAF receptor. These results indicate that PAF receptor coupling activates endometrial PtdIns(4,5)P2-specific phospholipase C only in the secretory phase of the menstrual cycle, suggesting that the PAF response may be under ovarian steroid regulation. It is proposed that the ability of the endometrium to respond to PAF appears to be a feature of the preparation of this tissue for implantation and that the second messengers generated may play a role in cellular processes involved in the maternal recognition of very early human pregnancy.

Endothelin-like immunoreactivity in human endometrium

Endothelin-like immunoreactivity (ET-IR) was detected immunocytochemically in glandular epithelium and vascular endothelium of human endometrium and myometrium. Primary antibody was raised in rabbits against the carboxy-terminal heptapeptide of endothelin 1 (ET-1), ET-1(15-21), and compared with antibodies raised against the cyclized amino-terminal, ET-1(2-13), and commercially obtained antibodies against the whole ET-1 or ET-3 molecule. Binding was visualized using the peroxidase technique in sections counter-stained with haemalum. Staining was seen in each of 15 sections from eight women in the proliferative (five) or secretory (three) phase of the cycle. Intense staining was present in the cytoplasm of endometrial glands and vascular endothelium, and was greatest at the endometrial-myometrial junction. The pattern of staining was similar with all primary antibodies tested. The demonstration of ET-IR in endometrium suggests that the endothelins may play a role in control of the uterine vascular bed.