The roles of the cyclo-oxygenases types one and two in prostaglandin synthesis in human fetal membranes at term

Preterm labor in the absence of acute histologic chorioamnionitis is characterized by cellular senescence of the chorioamniotic membranes

BACKGROUND

Decidual senescence has been considered a mechanism of disease for spontaneous preterm labor in the absence of severe acute inflammation. Yet, signs of cellular senescence have also been observed in the chorioamniotic membranes from women who underwent the physiological process of labor at term.

OBJECTIVE

We aimed to investigate whether, in the absence of acute histologic chorioamnionitis, the chorioamniotic membranes from women who underwent spontaneous preterm labor or labor at term exhibit signs of cellular senescence.

STUDY DESIGN

Chorioamniotic membrane samples were collected from women who underwent spontaneous preterm labor or labor at term. Gestational age-matched nonlabor controls were also included. Senescence-associated genes/proteins were determined using reverse transcription quantitative polymerase chain reaction analysis (n = 7-9 each for array; n = 26-28 each for validation), enzyme-linked immunosorbent assays (n = 7-9 each), immunoblotting (n = 6-7 each), and immunohistochemistry (n = 7-8 each). Senescence-associated β-galactosidase activity (n = 7-11 each) and telomere length (n = 15-22 each) were also evaluated.

RESULTS

In the chorioamniotic membranes without acute histologic chorioamnionitis: (1) the expression profile of senescence-associated genes was different between the labor groups (term in labor and preterm in labor) and the nonlabor groups (term no labor and preterm no labor), yet there were differences between the term in labor and preterm in labor groups; (2) most of the differentially expressed genes among the groups were closely related to the tumor suppressor protein (TP53) pathway; (3) the expression of TP53 was down-regulated in the term in labor and preterm in labor groups compared to their nonlabor counterparts; (4) the expression of CDKN1A (gene coding for p21) was up-regulated in the term in labor and preterm in labor groups compared to their nonlabor counterparts; (5) the expression of the cyclin kinase CDK2 and cyclins CCNA2, CCNB1, and CCNE1 was down-regulated in the preterm in labor group compared to the preterm no labor group; (6) the concentration of TP53 was lower in the preterm in labor group than in the preterm no labor and term in labor groups; (7) the senescence-associated β-galactosidase activity was greater in the preterm in labor group than in the preterm no labor and term in labor groups; (8) the concentration of phospho-S6 ribosomal protein was reduced in the term in labor group compared to its nonlabor counterpart, but no differences were observed between the preterm in labor and preterm no labor groups; and (9) no significant differences were observed in relative telomere length among the study groups (term no labor, term in labor, preterm no labor, and preterm in labor).

CONCLUSION

In the absence of acute histologic chorioamnionitis, signs of cellular senescence are present in the chorioamniotic membranes from women who underwent spontaneous preterm labor compared to those who delivered preterm in the absence of labor. However, the chorioamniotic membranes from women who underwent spontaneous labor at term did not show consistent signs of cellular senescence in the absence of histologic chorioamnionitis. These results suggest that different pathways are implicated in the pathological and physiological processes of labor.

Vascular Endothelial Growth Factor Activation of Intramembranous Absorption: A Critical Pathway for Amniotic Fluid Volume Regulation

OBJECTIVE

The purpose of this review is to propose a critical role for vascular endothelial growth factor (VEGF) in mediating the transfer of amniotic fluid from the amniotic compartment through the fetal membranes and fetal surface of the placenta into fetal blood.

METHODS

Experimental findings in humans and animal models on the action of VEGF in mediating fluid transfer are reviewed and interpreted in order to postulate a proposed mechanism for VEGF regulation of amniotic fluid absorption through the fetal membranes and placenta.

RESULTS

Recent scientific advances suggest that up-regulation of VEGF gene expression in the amnion and chorion is associated with increased transfer of amniotic fluid into fetal blood. The possible mechanisms of action for VEGF appear to involve regulation of intramembranous blood vessel proliferation and membrane transport via passive permeation as well as nonpassive transcytotic vesicular movement of fluid.

CONCLUSION

Currently evolving concepts suggest that amniotic fluid volume is regulated through modulation of the rate of intramembranous absorption of amniotic fluid by both passive and nonpassive mechanisms. The permeability factor VEGF appears to be a critical regulator of amniotic fluid transport in the fetal membranes.

The influence of adiponectin on the transcriptomic profile of porcine luteal cells

Reproductive functions are closely related to nutritional status. Recent studies suggest that adiponectin may be a hormonal link between them. Adiponectin is an adipocytokine, abundantly expressed in adipose tissues. It plays a dominant role in lipid and carbohydrate metabolism by stimulating fatty acid oxidation, decreasing plasma triglycerides, and increasing cells' sensitivity to insulin and has direct antiatherosclerotic effects. The hormone is also postulated to play a modulatory role in the regulation of the reproductive system. The aim of this study was to identify differentially expressed genes (DE-genes) in response to adiponectin treatment of porcine luteal ovarian cells. The global expression of genes in the porcine ovary was investigated using the Porcine (V2) Two-color gene expression microarray, 4 × 44 (Agilent, USA). Analysis of the microarray data showed that 701 genes were differentially expressed and 389 genes showed a fold change greater than 1.2 (p < 0.05). Among this number, 186 genes were up-regulated and 203 were down-regulated. The list of DE-genes was used for gene ontology analyses. The biological process list was generated from up-regulated and down-regulated DE-genes. We found that up-regulated products of DE-genes take part in 30 biological processes and down-regulated products in 9. Analysis of the interaction network among DE-genes showed that adiponectin interacts with genes involved in important processes in luteal cells. These results provide a basis for future work describing the detailed interactions and relationships explaining local regulation of adiponectin actions in the ovary of pigs.

A possible role of aryl hydrocarbon receptor in spontaneous preterm birth

Preterm birth (PTB) is defined as birth before 37 weeks of gestation and is a leading cause of neonatal mortality and morbidity. To date, the etiology of spontaneous PTB (sPTB) remains unclear; however, intrauterine bacterial infection-induced inflammation is considered to be one of the major triggers. Aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor. Upon activation, AhR signaling mediates many biological processes. AhR is abundantly expressed in human placentas, primarily in trophoblasts, and several fetal organs and tissues. The activation of AhR signaling can modulate inflammatory responses via promoting production of pro-inflammatory cytokines by the placenta and fetal membranes. These cytokines could enhance expression and/or activity of cyclooxygenase-2 (COX2) in human trophoblasts and amniotic epithelia, which in turn stimulate synthesis and release of prostaglandins (PGs; e.g., PGE2 and PGF2α). Given the discovery of a number of natural and endogenous AhR ligands in human, we hypothesize that in a subset of patients with high AhR expression in placentas and fetal membranes, repeated exposure to these AhR ligands hyperactivates AhR, inducing hyperactivation of the cytokines/COX2/PGs pathway, resulting in myometrial contractions, ultimately leading to sPTB. We further hypothesize that hyperactivation of this AhR pathway can induce sPTB either directly or in synergy with the bacterial infection. Proof of this hypothesis may provide a novel mechanism underlying sPTB.

Nuclear factor kappa B activation occurs in the amnion prior to labour onset and modulates the expression of numerous labour associated genes

BACKGROUND

Prior to the onset of human labour there is an increase in the synthesis of prostaglandins, cytokines and chemokines in the fetal membranes, particular the amnion. This is associated with activation of the transcription factor nuclear factor kappa B (NFκB). In this study we characterised the level of NFκB activity in amnion epithelial cells as a measure of amnion activation in samples collected from women undergoing caesarean section at 39 weeks gestation prior to the onset of labour.

METHODOLOGY/PRINCIPAL FINDINGS

We found that a proportion of women exhibit low or moderate NFκB activity while other women exhibit high levels of NFκB activity (n = 12). This activation process does not appear to involve classical pathways of NFκB activation but rather is correlated with an increase in nuclear p65-Rel-B dimers. To identify the full range of genes upregulated in association with amnion activation, microarray analysis was performed on carefully characterised non-activated amnion (n = 3) samples and compared to activated samples (n = 3). A total of 919 genes were upregulated in response to amnion activation including numerous inflammatory genes such cyclooxygenase-2 (COX-2, 44-fold), interleukin 8 (IL-8, 6-fold), IL-1 receptor accessory protein (IL-1RAP, 4.5-fold), thrombospondin 1 (TSP-1, 3-fold) and, unexpectedly, oxytocin receptor (OTR, 24-fold). Ingenuity Pathway Analysis of the microarray data reveal the two main gene networks activated concurrently with amnion activation are i) cell death, cancer and morphology and ii) cell cycle, embryonic development and tissue development.

CONCLUSIONS/SIGNIFICANCE

Our results indicate that assessment of amnion NFκB activation is critical for accurate sample classification and subsequent interpretation of data. Collectively, our data suggest amnion activation is largely an inflammatory event that occurs in the amnion epithelial layer as a prelude to the onset of labour.

Cyclooxygenase immunohistochemical staining in the human ductus arteriosus after 24 weeks of gestational age

Cyclooxygenase inhibitors (CI) which contained risks to fetal health were one of the most effective tocolytics. In order to indirectly investigate the effects of CI in human ductus arteriosus, immunohistochemical staining for cyclooxygenase-1 (COX1) and cyclooxygenase-2 (COX2) was evaluated in post-mortem fetuses with gestational ages between 24 and 34 weeks. Neither COX1 nor COX2 staining was related to gestational age. COX1 and COX2 staining in the vessel walls were not related to each other. COX1 staining in the endothelium, inner media and outer media were positively correlated with each other (COX1 endothelium vs IM staining Spearman's rho statistic [rs] = 0.721, p = 0.001; COX1 endothelium vs OM staining [rs] = 0.634, p = 0.004; COX1 IM vs OM staining [rs] = 0.931, p = 0.001). COX2 staining of endothelium was not correlated with either IM or OM staining. In conclusion, COX2 staining in the post-mortem specimens of human ductus arteriosus between 24 and 34 weeks is weak and limited to the endothelium.

Labor and inflammation increase the expression of oxytocin receptor in human amnion

The oxytocin/oxytocin receptor (OXT/OXTR) system plays an important role in the regulation of parturition. The amnion is a major source of prostaglandins and inflammatory cytokine synthesis, which increase both before and during labor. Amnion is a noncontractile tissue; therefore, the role played by OXT/OXTR in this tissue will be fundamentally different from the role played in myometrial contractions. In the present study, we demonstrate increased OXTR mRNA and protein concentrations in human amnion epithelial cells associated with the onset of labor. We show that incubation of primary human amnion epithelial cells with IL1B results in a rapid, transient up-regulation of OXTR mRNA expression, which peaks in prelabor samples after 6 h. Incubation of prelabor amnion epithelial cells with OXT results in a marked increase of prostaglandin E(2) synthesis, and we demonstrate that OXT activates the extracellular signal-regulated protein kinase signal transduction pathway to stimulate up-regulation of cyclo-oxygenase 2 in human amnion epithelial cells. The increased ability of human amnion to produce prostaglandins in response to OXT treatment suggests a complementary role for the OXT/OXTR system in the activation of human amnion and the onset of labor.

[Indometacin: come back of a controversial tocolytic? Obstetrical point of view]

The main aim of tocolysis is to improve the health of newborns. Given the modest impact in terms of perinatal health of tocolysis we must emphasize the use of tocolytics which, equally effective, have fewer maternal side effects than beta-agonists and are devoid of potential complications for mother and the newborn. Inhibitors of prostaglandin synthesis and calcium antagonists of oxytocin seem to meet these criteria. The recent papers for the use of NSAIDs provide no fundamentally new scientific data. This therapy is potentially associated with severe neonatal complications and superiority to calcium channel blockers or antagonists of oxytocin in terms of prolongation of pregnancy is not established. It seems reasonable to reserve them for special situations by their severity, precocity of the age of gestation or by the ineffectiveness of other treatments. In practice, it is recommended not to use NSAIDs first line, beyond 32 weeks and treatment should be of short duration (less than 48 to 72 hours). Ideally, delivery should not occur within 48 hours after stopping treatment.

Evidence for a spatial and temporal regulation of prostaglandin-endoperoxide synthase 2 expression in human amnion in term and preterm parturition

CONTEXT

Prostaglandin-endoperoxide synthase 2 (PTGS2) is a key enzyme involved in parturition. PTGS2 mRNA was found to be differentially expressed between placental amnion (amnion overlying the placental disc) and reflected amnion (amnion of the extraplacental chorioamniotic membranes) in term placentas.

OBJECTIVE

The aim was to evaluate the spatial and temporal regulation of PTGS2 expression in the amnion and the chorion-decidua.

DESIGN

PTGS2 expression was analyzed in the amnion and chorion-decidua obtained from 32 women: term not in labor (n = 12), term in labor (n = 12), and preterm labor (n = 8), by immunoblotting and densitometry. Prostaglandin E(2) (PGE(2)) in the amnion and chorion-decidua was measured by a specific immunoassay.

RESULTS

Compared to preterm labor cases, PTGS2 expression increased at term before the onset of labor far more prominently in placental amnion (4.5-fold; P = 0.002) than in reflected amnion (1.4-fold; P = 0.007). There was a significant increase in PTGS2 expression in reflected amnion (2.9-fold; P < 0.01) but not in placental amnion with labor at term. PTGS2 expression was higher in reflected amnion than in chorion-decidua in labor at term (2.9-fold; P < 0.01). PTGS2 was barely detected in amnion and chorion-decidua with preterm labor. Expression of PGE(2) showed a good correlation with PTGS2 expression (r = 0.722; P < 0.001).

CONCLUSION

PTGS2 expression in the amnion shows a distinct spatial and temporal regulation. Spontaneous labor at term and pathological preterm labor clearly differ in amniotic PTGS2 and PGE(2) abundance. Our observations underscore the biological significance of the amnion and amniotic fluid in human parturition.

Experience of the use of nimesulide, a cyclo-oxygenase-2 selective prostaglandin synthesis inhibitor, in the prevention of preterm labour in 44 high-risk cases

We report pregnancy outcome and fetal side effects in women at high risk of second trimester loss and early preterm delivery treated with nimesulide. This was a prospective observational study of 44 women treated with nimesulide from 17 to 32 weeks. All women underwent weekly ultrasound scans for AFI, Doppler studies of the ductus arteriosus and transvaginal assessment of cervical length. Outcome data were collected. Oligohydramnios occurred in 54% of cases; this returned to normal in all cases on discontinuation of treatment. There were no cases of constriction of the ductus arteriosus. Thirty-nine women took home a live baby. The mean gestation at delivery was 33 weeks and 1 day and the mean birth weight was 2105 g. Nimesulide appeared to have a significant benefit in women at high risk of preterm delivery with no long-term harmful effects on the fetus if monitored closely with an intensive ultrasound scanning regimen. Randomised placebo controlled trials are required to assess fully the benefit of COX-2 selective and specific prostaglandin synthesis inhibitors.

Association of preterm birth with sustained postnatal inflammatory response

OBJECTIVE

To investigate fetal or neonatal inflammatory patterns based on 25 inflammatory markers in neonatal dried blood spots samples from infants born preterm and term, collected several days after birth.

METHODS

Dried blood spots samples from 160 neonates were analyzed for 25 inflammatory markers using multiplex technology: 26 neonates born very preterm (before 32 weeks of gestation), drawn at a mean 6 days (95% confidence interval [CI], 5-7 days) after birth; 52 born preterm (32-36 weeks of gestation), drawn at mean 5 days (95% CI, 5-6 days) after birth; and 82 born at term (at or after 37 weeks of gestation), drawn at mean 5 days (95% CI, 5-5 days) after birth. Markers statistically significantly associated with preterm birth were analyzed in a multivariable model together with maternal and neonatal risk factors for preterm birth.

RESULTS

Elevated levels of interleukin (IL)-1beta, IL-6, soluble IL-6ralpha, IL-8, matrix metalloproteinase-9, and transforming growth factor-beta1 and decreased levels of IL-18, brain-derived neurotrophic factor, and C-reactive protein were associated with preterm birth. Maternal risk factors could explain only an increase of IL-1beta, whereas neonatal factors could explain several of the elevated and decreased inflammatory markers in the dried blood spots samples from the infants born preterm compared with the infants born at term.

CONCLUSION

The differences in levels of inflammatory markers in dried blood spots samples from infants born preterm compared with infants born at term supports the hypothesis that inflammation of fetal origin might be a cause of preterm birth.

LEVEL OF EVIDENCE

II.

Pharmacological prevention of prematurity

The acute treatment of premature labour is successful for delaying delivery for short periods of time. Acute tocolysis does not have a significant impact on perinatal outcome. This is likely to be because the process leading to labour occurs over a longer timeframe and therefore therapies instigated as preventative measures are more likely to be successful in delaying delivery. Identification of women at risk of preterm birth is essential to ensure therapies are targeted appropriately. Risk assessments for prediction include previous obstetric history, previous episode of threatened preterm labour, fetal fibronectin status and cervical length. Several groups of pharmacological agents have been studied for the prophylactic treatment of preterm labour. There is no evidence to support the use of tocolytics such as beta-mimetics and oxytocin receptor antagonists. Current studies of calcium channel blockers are too small to draw final conclusions. Non-steroidal anti-inflammatory drugs are associated with side effects on the fetal renal system and ductus arteriosus, making them suitable only for long term use in pregnancy with close ultrasound surveillance. Antibiotics used early in pregnancy in women with abnormal vaginal flora may reduce the risk of preterm birth; however, in women with other risk factors for preterm birth, metronidazole may be associated with an increased risk. The use of progesterone in women with a history of very early preterm labour is likely to be beneficial for preventing preterm labour.

Preterm labour. Biochemical and endocrinological preparation for parturition

Preterm delivery is a common obstetric problem occurring in about 1 in 10 of all births. Preterm babies have a high risk of morbidity and mortality. Such births account for 75% of all major neonatal problems. At the other end of the spectrum, prolonged pregnancy is also a subject of concern because it too is associated with increased fetal morbidity and mortality. Despite extensive research, the mechanisms that control the length of human pregnancy and signal the onset of labour have not been fully determined. This chapter will discuss basic principles in the biology of parturition and the regulation of contraction-associated proteins including the oxytocin receptor. The major pathways regulating contractions and the transcriptional regulation of the main genes that are known to be involved in the onset of labour and parturition will be examined. Some new potentially therapeutic strategies for the biochemical management of preterm labour will be discussed.

Effects of maternally administered drugs on the fetal and neonatal kidney

The number of pregnant women and women of childbearing age who are receiving drugs is increasing. A variety of drugs are prescribed for either complications of pregnancy or maternal diseases that existed prior to the pregnancy. Such drugs cross the placental barrier, enter the fetal circulation and potentially alter fetal development, particularly the development of the kidneys. Increased incidences of intrauterine growth retardation and adverse renal effects have been reported. The fetus and the newborn infant may thus experience renal failure, varying from transient oligohydramnios to severe neonatal renal insufficiency leading to death. Such adverse effects may particularly occur when fetuses are exposed to NSAIDs, ACE inhibitors and specific angiotensin II receptor type 1 antagonists. In addition to functional adverse effects, in utero exposure to drugs may affect renal structure itself and produce renal congenital abnormalities, including cystic dysplasia, tubular dysgenesis, ischaemic damage and a reduced nephron number. Experimental studies raise the question of potential long-term adverse effects, including renal dysfunction and arterial hypertension in adulthood. Although neonatal data for many drugs are reassuring, such findings stress the importance of long-term follow-up of infants exposed in utero to certain drugs that have been administered to the mother.

Nitric oxide (NO) inhibits prostaglandin E2 9-ketoreductase (9-KPR) activity in human fetal membranes

Nitric oxide (NO) synthesized by fetal membranes may act either directly inhibiting myometrium contractility or indirectly interacting with tocolytic agents as prostaglandins (PGs). Here we examined if NO could modulate prostaglandin E(2) 9-ketoreductase (9-KPR) activity in human fetal membranes (HFM). 9-KPR is the enzyme that converts PGE(2) into PGF(2alpha), the main PGs known to induce uterine contractility at term. Chorioamnion explants obtained from elective caesareans were incubated with aminoguanidine (AG), an iNOS inhibitor, or NOC-18, a NO donor. NOC-18 (2mM) increased PGE(2) production and diminished PGF(2alpha) synthesis in HFM. AG presented the opposite effect. When we evaluated the activity of 9-KPR by the conversion of [(3)H]-PGE(2) into [(3)H]-PGF(2alpha) and 13,14-dihidro-15-keto prostaglandin F(2alpha) (the PGF(2alpha) metabolite), we found that NOC-18 inhibited 9-KPR activity. Interestingly, AG did not elicit any effect on 9-KPR but l-NAME, a non-selective NOS inhibitor, significantly increased its activity. Our data suggests that exogenous NO inhibits 9-KPR activity in HFM, thus modulating the synthesis of important labor mediators as PGF(2alpha).

Contribution of inducible nitric oxide synthase and cyclooxygenase-2 to apoptosis induction in smooth chorion trophoblast cells of human fetal membrane tissues

We examined the contribution of apoptosis- and oxidative stress-associated genes to apoptosis induction in trophoblast cells of human fetal membrane tissues undergoing apoptosis during in vitro incubation. RT-PCR analyses demonstrated an increased level of HO-1, Mn-SOD, Cox-2, iNOS, TNFalpha, TNFR1, IL-1beta, IL-6, Bax, Bak, and Bad gene expression, while Bcl-2 mRNA expression level decreased. Western blot analyses demonstrated an increase in iNOS, Cox-2, and HO-1 protein levels; a decrease in pro-caspase-3 and 9, proform-PARP, and Apaf-1 protein levels; a leakage of cytochrome c from the mitochondria. An antioxidative reagent, general and selective Cox-2 inhibitors, and an iNOS inhibitor suppressed in vitro progression of the apoptosis. Furthermore, an NO donor reagent induced apoptosis in primary cultured trophoblast cells. Therefore, we concluded that the induction of apoptosis in the smooth chorion trophoblasts is mediated through oxidative stress induction followed by mitochondria damage, suggesting that iNOS and Cox-2 play an important role in the apoptosis induction in trophoblasts of human fetal membrane tissues.

The role of CCAAT/enhancer-binding protein beta in the transcriptional regulation of COX-2 in human amnion

Human labour is associated with increased prostaglandin synthesis within the uterus by the action of the inducible type-2 cyclo-oxygenase enzyme (COX-2). A major source of prostaglandin is the fetal membranes, in particular the amnion, in which expression of COX-2 increases in late pregnancy and with labour. The COX-2 gene promoter contains several putative transcription factor binding sites including those for NF-kappaB, AP-1 and C/EBP and therefore has the features of a rapid response gene. We have previously shown that, in amnion, the NF-kappaB DNA-binding sites in the COX-2 promoter are essential for gene expression and that there is an increase in NF-kappaB activity in amnion with the onset of labour. In this study, we demonstrate that in primary human amnion cells, CCAAT/enhancer-binding protein beta (C/EBPbeta) DNA-binding sites are crucial for the function of the COX-2 gene promoter. Three potential C/EBPbeta DNA-binding sites were identified within the COX-2 promoter which were shown to bind to C/EBPbeta but not to C/EBPalpha, C/EBPdelta, CREB (cAMP responsive element modulator) or CREM. Luciferase reporter constructs with site-directed mutagenesis of the three C/EBPbeta sites in the COX-2 promoter showed reduced expression of luciferase in transient transfection studies. However, comparison of C/EBPbeta protein levels and their DNA-binding activity from cells obtained before and after labour showed no significant differences. This suggests that although C/EBPbeta plays an essential constitutive role in the expression of COX-2, C/EBPbeta may not be directly involved in its regulation in association with human labour.

The abortifacient effects from the seeds of Coix lachryma-jobi L. var. ma-yuen Stapf

This study evaluated the abortifacient effects of the extracts of seeds of Coix lachryma-jobi L. var. ma-yuen Stapf (adlay) in pregnant rats. Pregnant rats were treated with oral administration of adlay seed extracts on d 6 of pregnancy and their fetuses were examined for growth and malformations on d 20 of pregnancy. Following oral administration of 1 g/kg body weight of water extracts but not methanolic extracts, fetal resorptions were significantly increased and mortality of postimplantation was increased. There were no significant differences in the uterine and fetal weight compared to control. Fetal malformations were not observed in the adlay seed extracts-treated pregnant rats. The contractile activity of uteri isolated from rats on d 20 of pregnancy was assessed. The spontaneous uterine contractions were significantly enhanced in rats treated with water extracts of adlay seeds (1 g/kg body weight). Immunoblotting of uteri from rats treated with water extracts of adlay seeds demonstrated an induction of cyclooxygenase-2 (COX-2) protein expression. The water extracts of adlay seeds also enhanced extracellular signal-regulated protein kinase (ERK) 1/2 phosphorylation and protein kinase C (PKC)-alpha translocation from cytosolic to particulate fractions in uteri. These results indicate that the water extracts of adlay seeds are capable of inducing embryotoxicity and enhancing uterine contractility during pregnancy. The enhanced activities of PKC-alpha, ERK1/2, and COX-2 may contribute to these responses.

TOCOX--a randomised, double-blind, placebo-controlled trial of rofecoxib (a COX-2-specific prostaglandin inhibitor) for the prevention of preterm delivery in women at high risk

OBJECTIVE

To assess the safety and efficacy of the long term prophylactic use of rofecoxib (a COX-2-specific inhibitor) in women at high risk of preterm delivery.

DESIGN

A randomised, double-blind, placebo-controlled trial.

SETTING

Queen Charlotte's and Chelsea Hospital, London and Guys and St Thomas' Hospitals, London.

POPULATION

Ninety-eight singleton pregnancies at high risk of preterm labour.

METHODS

Treatment from 16 to 32 weeks. Weekly ultrasound surveillance.

MAIN OUTCOME MEASURES

Fetal renal function and ductus arteriosus blood flow changes. Preterm delivery rates and neonatal outcome.

RESULTS

Rofecoxib caused a reduction in hourly fetal urine production rates (-34%, 95% CI -13 to -50%, P = 0.004) and amniotic fluid index (-2.2, 95% CI -3.2 to -1.2, P < 0.001). This effect did not increase with time on treatment and reversed in all cases on discontinuation of treatment. Rofecoxib had an effect on the ductus arteriosus, increasing maximum systolic velocity (0.1 m/s, 95% CI 0.03-0.16, P = 0.02) and minimum diastolic velocity (0.007 m/s, 95% CI 0.0007-0.013, P= 0.03). This effect increased with time on treatment but was reversed with discontinuation of treatment and had no long term clinical sequelae. There was no difference in preterm delivery rates <30 weeks (28% on placebo vs 33% on rofecoxib, Mantel-Haensel [M-H]-adjusted risk 1.11, 95% CI 0.67-1.87). There were more deliveries <37 weeks in those on rofecoxib (40%vs 67%, M-H-adjusted risk 1.59, 95% CI 1.09-2.32). Rates of preterm prelabour rupture of membranes (PPROM) were higher in those on rofecoxib (RR 2.5, 95% CI 1.3-4.7).

CONCLUSION

Rofecoxib has a significant but reversible effect on fetal renal function and the ductus arteriosus. It does not reduce the incidence of early preterm delivery <30 weeks and is associated with an increased risk of delivery before 37 weeks in women at high risk.

High-performance liquid chromatographic analysis of a selective cyclooxygenase-1 inhibitor SC-560 in rat serum: application to pharmacokinetic studies

A method of analysis of SC-560 (5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole) in biological fluids is necessary to study the kinetics of in vitro and in vivo metabolism. A simple high-performance liquid chromatographic method was developed for simultaneous determination of SC-560 and other products of metabolism in rat serum. Serum (0.1 ml) was precipitated with acetonitrile after addition of the internal standard, testosterone 17-propionate. Separation was achieved on a C(8) column with UV-detection at 240 nm. The calibration curve was linear ranging from 0.02 to 100 microg/ml. The mean recovery was >86.7%. Precision of the assay was <10% (R.S.D.%), and was within 15% at the limit of quantitation (20 ng/ml). Bias of the assay was lower than 15.5%. The limit of detection was 10 ng/ml for a 0.1 ml sample. The assay was applied successfully to the in vivo kinetic study of SC-560 in rats.

Expression and localization of cell adhesion molecules in human fetal membranes during parturition

There is increasing evidence to support the view that human parturition represents an inflammatory process. We have previously demonstrated that parturition is associated with leukocyte invasion and pro-inflammatory cytokine production in the cervix and myometrium. Furthermore, we have shown that several cell adhesion molecules are upregulated in these tissues during labor. In fetal membranes, previous studies have shown intercellular adhesion molecule-1 (ICAM-1) upregulation in association with labor. The role of other adhesion molecules has not been explored. The aims of this study were, therefore, to determine the expression of ICAM-1, platelet endothelial cell adhesion molecule (PECAM), vascular cell adhesion molecule (VCAM) and E-selectin in pre- and post-laboring amnion and choriodecidua and to identify cell types responsible for their expression. Biopsies of fetal membranes were obtained from pregnant women delivered by caesarean section before the onset of labor (n = 8) and following spontaneous vaginal delivery (n = 8). Cell adhesion molecules were identified using immunohistochemistry and messenger RNA expression quantified using Northern analysis. We found that following labor, ICAM-1 mRNA expression was significantly upregulated in amnion and choriodecidua (P < 0.05). PECAM mRNA expression was also increased in choriodecidua (P < 0.05). The main cell types responsible for adhesion molecule expression were leukocytes, amniotic epithelial cells and endothelial cells. The upregulation of ICAM-1 and PECAM mRNA expression in fetal membranes following labor provides further evidence that fetal membranes play an important role in the inflammatory process of parturition.

24 hour rhythm in the timing of pre-labour spontaneous rupture of membranes at term

OBJECTIVE

To study the timing of pre-labour spontaneous rupture of membranes (SROM) in term pregnancies.

DESIGN

Prospective cohort.

SETTING

A maternity hospital in the United Kingdom.

SAMPLE

Women who were more than 37 weeks gestation with confirmed spontaneous rupture of membranes and not in labour after 4 h.

METHODS

Women who were admitted into labour ward with a diagnosis of spontaneous rupture of membranes after 37 weeks of gestation were included. The women's demographic details were recorded and inquiries about whether they had sexual intercourse in the preceding 12 h. The final outcome of their pregnancy was recorded and analysed.

MAIN OUTCOME MEASURES

(1) The exact time of spontaneous rupture of membranes, (2) the time of onset of spontaneous labour, (3) delivery details.

RESULTS

One hundred and ninety-six women were studied. A 24 h rhythm in the timing of spontaneous rupture of membranes was found with 33.2% occurring between 00:00 and 04:00 h. When contractions representing the onset of labour occurred there was no diurnal rhythm to the timing of onset of contractions.

CONCLUSIONS

There is a 24 h rhythm in the timing of spontaneous rupture of membranes in term gestations. The physiological reasons for this rhythm are not understood at the present time.

Rofecoxib Versus Magnesium Sulfate to Arrest Preterm Labor: A Randomized Trial

OBJECTIVE

To compare oral rofecoxib with intravenous magnesium sulfate as a tocolytic.

METHODS

This was a randomized study of patients who were between 22 and 34 weeks of gestation with preterm labor. Patients were randomly assigned to receive either daily oral rofecoxib (50 mg) or intravenous magnesium sulfate for a maximum of 48 hours. Outcome variables included delay of delivery for 48 hours and the incidence of side effects. Data were analyzed by using the Student t test, Mann-Whitney U test, chi(2) test, and repeated-measures analysis of variance. Sample size calculations were based on previous studies of tocolytic efficacy.

RESULTS

Two hundred fourteen patients were randomly assigned (105 received rofecoxib and 109 received magnesium sulfate). Delivery was delayed for 48 hours in 95 (90.4%) and 96 (88%) of the patients in the rofecoxib and magnesium sulfate groups, respectively (relative risk 0.97; 95% confidence interval 0.89, 1.06). To show a statistically significant benefit in delay of delivery past 48 hours, a total of 2,686 patients would be required in each group. There was no difference between the groups over the course of the study in cervical dilatation, amniotic fluid index, or cervical length by vaginal ultrasonography. The median hospital days on the original admission were also similar at 2 for both groups (P =.10). There was a higher reported incidence of maternal side effects in the magnesium sulfate group (relative risk 1.81; 95% confidence interval 1.07, 3.06). There was no difference in the incidence of neonatal side effects.

CONCLUSION

There was no difference between oral rofecoxib and intravenous magnesium sulfate in arresting preterm labor.

Response of fetal prostanoids, nitric oxide, and ductus arteriosus to the short- and long-term antenatal administration of celecoxib, a selective cyclo-oxygenase-2 inhibitor, in the pregnant rabbit

OBJECTIVE

The purpose of this study was to test the hypothesis that the maternal administration of therapeutic doses of celecoxib would not affect ductus arteriosus patency or alter renal and hepatic prostanoids in the fetal rabbit.

STUDY DESIGN

Pregnant rabbits received celecoxib from 13 to 20 days (celecoxib-A), from 13-28 days (celecoxib-B), or vehicle from 13 to 28 days by gavage. Fetal serum and lung tissue were analyzed for nitric oxide oxidation products. Fetal plasma, liver, and kidney were analyzed for prostaglandin levels.

RESULTS

The ductus arteriosus was patent in both treatment groups. Celecoxib induced elevations of plasma prostaglandin E(2) production. In celecoxib-B liver and kidney, the 6-keto-prostaglandin F(1alpha) and prostaglandin F(2alpha) levels were increased, and the prostaglandin E(2) and thromboxane B(2) levels were decreased substantially.

CONCLUSION

This preliminary evaluation demonstrates that the maternal administration of celecoxib does not influence fetal ductus arteriosus patency adversely in rabbits.

Prostaglandin inhibitors in preterm labour

Prematurity accounts for the majority of neonatal morbidity and mortality in the developed world. The process of labour resembles inflammation, with prostaglandin and cytokine production both before and during labour. Anti-inflammatory drugs therefore have the potential to prevent preterm delivery. Indomethacin is the only tocolytic drug proven to delay delivery beyond 37 weeks and to reduce the incidence of low birth weight (<2500 g). There are, however, fetal side-effects such as ductal constriction and impaired renal function associated with its use. It is the type 2 isoform of cyclo-oxygenase (COX-2), which is important for the production of prostaglandins within intrauterine tissues and that up-regulation of COX-2 is associated with labour. Although indomethacin is currently the most common non-steroidal anti-inflammatory drug (NSAID) used in the treatment of preterm labour, it was hoped that COX-2-selective drugs, used as tocolytics, would target COX-2 activity and potentially spare COX-1-specific fetal side-effects. Experience with sulindac and nimesulide has been linked with both constriction of the ductus arteriosus and oligohydramnios. It is unclear whether this is due to COX-2-dependent side-effects, or due to accumulation of drug in the fetal circulation leading to levels that would cause COX-1 inhibition. Currently, the use of COX-2-selective drugs should therefore be confined to randomized controlled trials.

The effects of non-steroidal anti-inflammatory compounds on human myometrial contractility

OBJECTIVE

To investigate the effects of inhibitors of COX-1 or COX-2 on myometrial prostaglandin synthesis and on spontaneous contractions in human myometrium.

METHODS

Cultured myometrial cells were incubated with SC 58560 (COX-1 selective inhibitor) or SC 58236 (COX-2 selective inhibitor), and the production of prostaglandins determined by ELISA. Spontaneously contracting strips of isolated gravid human lower segment myometrium were incubated with SC 58236, meloxicam, DFU, or nimesulide (COX-2 selective inhibitors), with SC 58560 (COX-1 selective inhibitor) or indomethacin (non-selective inhibitor).

RESULTS

SC 58236 inhibited the production of prostaglandins from myometrial cells, whereas SC 58560 had less effect. Nimesulide (100 microM) and indomethacin (300 microM) completely inhibited myometrial contractions, whereas meloxicam, DFU, SC 58236 and SC 58560 had less effect.

CONCLUSIONS

There was no relationship between the inhibition of prostaglandin production and the effects of the compounds on contractility. Myometrial prostaglandin synthesis does not seem to be essential for spontaneous contractility.

Progesterone represses interleukin-8 and cyclo-oxygenase-2 in human lower segment fibroblast cells and amnion epithelial cells

Labor is preceded by cervical ripening through upregulation of interleukin (IL)-1beta, IL-8, and increased prostaglandin synthesis via inducible type 2 cyclooxygenase (COX-2). Progesterone maintains myometrial quiescence during pregnancy. In this study, we examined the effects of IL-1beta and progesterone on IL-8 and prostaglandin E2 (PGE2) synthesis and IL-8 and COX-2 mRNA and promoter activity in amnion cells and lower segment fibroblast (LSF) cells. In both cell types, progesterone had no effect on basal IL-8 or PGE2 synthesis. In LSF cells, IL-1beta significantly increased IL-8 and PGE2 synthesis and COX-2 and IL-8 mRNA expression, but progesterone significantly attenuated these effects. In prelabor amnion cells, IL-1beta also increased IL-8 and PGE2 synthesis and both COX-2 and IL-8 mRNA and promoter expression; however, progesterone significantly attenuated these effects on IL-8 and PGE2 synthesis and COX-2 expression. In postlabor amnion cells, IL-1beta increased IL-8 and PGE2 synthesis and COX-2 expression, but progesterone did not attenuate the effect of IL-1beta upon IL-8 synthesis. Progesterone repression of IL-8 and COX-2 in LSF cells suggests that IL-8 and COX-2 have similar regulatory mechanisms in LSF cells and that progesterone may play a role in maintenance of cervical competence. The lack of effect of progesterone on IL-8 in postlabor cells may be the result of downregulation of the progesterone receptor during labor.

Prenatal effects of DuP-697-the irreversible, highly selective cyclooxygenase-2 inhibitor

DuP-697 (5-bromo-2-(4-fluorophenyl)-3-[4-(methylsulfonyl)phenyl]-thiophene), like celecoxib and rofecoxib, is a vicinal diaryl heterocycle highly selective cyclooxygenase-2 (COX-2) inhibitor. The aim of the study was to evaluate prenatal tolerability of DuP-697. The drug was administered orally in Tween 80 water suspension once a day to pregnant Wistar rats, on Days 7-18 of gestation. The initial dose, similar to the rat antipyretic dose, was set at 0.05 mg/kg. The middle dose, 3.5 mg/kg, corresponded to the rat anti-inflammatory and analgesic dose. The high dose was set at 35.0 mg/kg. Control animals received Tween 80 water suspension. On Day 21 of gestation, fetuses were delivered by laparotomy and double stained with alcian blue and alizarin red S or examined using the Wilson technique. Intrauterine growth retardation occurred in the groups exposed to the middle and highest dose of DuP-697. Minimal reactive and degenerative hepatic changes were found in both drug-exposed and control groups. Skeletal malformations were seen occasionally in all drug-treated and control groups. A significant increase in skeleton variations, such as delayed and asymmetrical ossification, was observed in fetuses exposed to the highest drug dose when compared with the control. These changes were not increased (P<0.1) in the middle drug-dose group. The experimentally-derived NOAEL for developmental toxicity was 0.05 mg/kg, and the corresponding LOAEL was 3.5 mg/kg.

Effect of selective vs. non-selective cyclo-oxygenase inhibitors on fetal membrane prostaglandin synthesis

Increased expression of the inducible isoform of cyclo-oxygenase (COX-2) and prostaglandin output from fetal membranes is a key stage in human parturition. Prostaglandin production can be inhibited by non-steroidal anti-inflammatory drugs (NSAIDs), but these may also inhibit cyclo-oxygenase enzymes in fetal tissues, and hence cause potentially serious side effects. We have compared the concentrations of NSAIDs that inhibit maximal PGE2 synthesis from intact human fetal membrane explants in vitro with those found in human plasma after standard anti-inflammatory treatment. The concentrations of all six drugs that caused a 50% inhibition of fetal membrane prostaglandin output were lower than average plasma levels achieved during treatment. This effect was greatest for nimesulide and indomethacin, indicating that these drugs require further study at low doses in vivo, as this could achieve the same tocolytic effect with diminished adverse fetal effect. These drugs were also the most potent inhibitors of fetal membrane prostaglandin output, consistent with their effects on COX-2 activity.

COX-2 inhibitors and their role in gynecology

This review summarizes current knowledge about the roles of cyclooxygenases and prostaglandins in reproductive medicine. With the development of COX-2 specific inhibitors, new therapeutic options are available to obstetricians and gynecologists, offering better-tolerated alternatives to conventional NSAIDs. The analgesic effectiveness of COX-2 specific inhibitors is well established, and they are already in use in a range of painful conditions. Both celecoxib and valdecoxib are indicated for the treatment of primary dysmenorrhea, and may be effective in postoperative pain, including hysterectomy, and pain associated with endometriosis. There is also speculation that COX-2 specific inhibitors may be effective tocolytic agents without the risks to the fetus seen with conventional NSAIDs. The role of COX-2 in oncogenesis is also under investigation, and COX-2 specific inhibitors may eventually be used in the prevention and treatment of gynecologic malignancies.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader will be able to describe the two types of cylooxygenase enzymes (COX), to list the effects and side effects of NSAIDs and COX-2 medications, and to outline the various changes in COX expression during pregnancy.

In vitro study of tocolytic effect of rofecoxib, a specific cyclo-oxygenase 2 inhibitor. Comparison and combination with other tocolytic agents

OBJECTIVE

The aim of this work was to study and compare the tocolytic effects of rofecoxib with indomethacin, ritodrine, nicardipine and atosiban. We also studied the combination of rofecoxib with each agent.

DESIGN

In vitro animal experimental study.

SETTING

Non-selective cyclo-oxygenase (COX) inhibitors have potent tocolytic effect. However, they also have major fetal side effects that seem to be due to COX-1 inhibition. A specific COX-2 inhibitor could be a potent tocolytic agent with less fetal toxicity.

SAMPLE

Myometrial strips from pregnant Wistar rats at 18 days of gestation.

METHODS

Isometric tension was recorded from 112 pregnant rat myometrial strips in vitro. Strips were exposed to increase molar concentration of one drug or combination.

MAIN OUTCOME MEASURES

Contractile activity was assessed by calculating the area under the curve, to obtain a dose-response curve of each drug. EC50 and mean maximal inhibiting concentration were compared using ANOVA. Chemical interaction was defined for each combination.

RESULTS

The in vitro tocolytic effect of rofecoxib was demonstrated. Contractile activity stopped at a concentration of 1.6 x 10(-7) M. Effective concentrations were 1000 times less than for indomethacin and significantly lower than ritodrine and atosiban. Rofecoxib combined with ritodrine had a synergic effect. Other combinations only had an additive effect.

CONCLUSIONS

Rofecoxib has a potent tocolytic effect in vitro. The high specificity and low effective concentrations of COX-2 may result in low fetal toxicity. Animal fetal side effects need to be explored.

Cyclooxygenase-1-selective inhibition prolongs gestation in mice without adverse effects on the ductus arteriosus

Preterm delivery is the leading cause of neonatal mortality and contributes significantly to infant morbidity. Classical cyclooxygenase (COX) inhibitors, such as indomethacin, which inhibit both COX-1 and COX-2, are effective for delaying premature labor, but their use is limited by serious complications to the fetus and neonate, including adverse effects on the ductus arteriosus (DA). Using isoform-selective inhibitors, we characterized the roles of the COX isoforms in the initiation of labor and the regulation of fetal and neonatal DA closure in mice. Chronic inhibition of COX-2 during pregnancy (gestation days 15-18) significantly increased neonatal mortality by preventing closure of the DA after birth, whereas acute COX-2 inhibition near the end of term (gestation day 18) constricted the fetal DA. In contrast, the inhibition of COX-1 during pregnancy lacked these prenatal and postnatal adverse effects on the DA and effectively delayed the initiation of full-term labor and LPS-induced preterm labor. These findings suggest that premature fetal DA closure or neonatal patent DA observed following indomethacin tocolysis in women may result from the inhibition of COX-2. Therefore, COX-1-selective inhibitors may provide effective treatment to delay preterm labor with fewer adverse effects on fetal or neonatal health than nonselective or COX-2-selective inhibitors.

Phenotypes of the COX-deficient mice indicate physiological and pathophysiological roles for COX-1 and COX-2

The development of mice deficient in either cyclooxygenase-1 (COX-1) or COX-2, as well as mice deficient in both COX isoforms, has provided models to elucidate the physiological and pathophysiological roles of these enzymes. The findings obtained with the COX-deficient mice suggest that COX-2 may be more important than COX-1 for supplying prostaglandins (PGs) to maintain tissue homeostasis. Furthermore, both isoforms may be involved in the development of diseases, such as inflammation and cancer. Therefore, the contribution of each isoform to the prevention or development of disease is more complex than originally described. Studies with the COX-deficient mice suggest that in addition to COX-2-selective inhibition, therapeutic advances may also be achieved with COX-1-selective inhibitors which lack gastrointestinal side effects.

Phospholipase A(2) and cyclooxygenase gene expression in human preimplantation embryos

Phospholipase A(2) (PLA(2)) and cyclooxygenase (COX) are two key enzymes in PG synthesis; the latter has two forms, COX-1 and COX-2. mRNA was extracted from single preimplantation embryos and examined for PLA(2), COX-1, and COX-2 gene expression by RT-PCR to investigate whether PLA(2) and COX genes are expressed in human preimplantation conceptuses from zygote to blastocyst stage and to compare COX-1 and COX-2 gene expression within the same stage of embryonic development. Expression of PLA(2), COX-1, and COX-2 was detected in 48, 37, and 45%, respectively, of total embryos examined. COX-1 was expressed in approximately 66% of early human preimplantation embryos from zygote to two-cell stage, whereas COX-2 was expressed in about 58% of later stage embryos from eight-cell to blastocyst stage (P < 0.05). Furthermore, COX-2 mRNA and protein were localized to trophectoderm in blastocyst stage embryos. In conclusion, PLA(2), COX-1, and COX-2 are expressed during early human embryonic development and may contribute to the production of PGs such as PGE(2) in human embryogenesis. COX-1 and COX-2 are differentially expressed, with COX-2 being primarily expressed by trophectoderm in late-stage human preimplantation embryos, which may promote embryonic differentiation and implantation.

Preterm labour

Studies in the past year have clarified the roles of inflammatory mediators in preterm labour. Exploration of possible genetic predisposition is just beginning. Ultrasound measurement of cervical length has the potential to predict women at risk of preterm delivery several weeks before it occurs. Biochemical testing such as fetal fibronectin can possibly increase its predictive value and differentiate true preterm labour from more innocent preterm contractions. The use of antibiotics for preterm premature rupture of membranes has been clarified with the ORACLE I trial, which shows health benefits for the neonate with the use of erythromycin, whereas antibiotics do not seem to play a beneficial role in spontaneous preterm labour without evidence of clinical infection. There have been further studies suggesting that agents other than beta-agonists are preferable for acute tocolysis and that repeated doses of corticosteroids should be used with caution.

Cyclooxygenase-2--10 years later

The enzyme cyclooxygenase (COX) catalyzes the first step of the synthesis of prostanoids. In the early 1990s, COX was demonstrated to exist as two distinct isoforms. COX-1 is constitutively expressed as a "housekeeping" enzyme in most tissues. By contrast, COX-2 can be up-regulated by various pro-inflammatory agents, including lipopolysaccharide, cytokines, and growth factors. Whereas many of the side effects of nonsteroidal anti-inflammatory drugs (NSAIDs) (e.g., gastrointestinal ulceration and bleeding, platelet dysfunctions) are caused by a suppression of COX-1 activity, inhibition of COX-2-derived prostanoids facilitates the anti-inflammatory, analgesic, and antipyretic effects of NSAIDs. During the past few years specific inhibitors of the COX-2 enzyme have emerged as important pharmacological tools for treatment of pain and arthritis. However, although COX-2 was initially regarded as a source of pathological prostanoids only, recent studies have indicated that this isoenzyme mediates a variety of physiological responses within the organism. The present review assesses recent advances in COX-2 research, with particular emphasis on new insights into pathophysiological and physiological functions of this isoenzyme.

Cyclooxygenase-2 inhibitor NS398 preserves neuronal function after hypoxia/ischemia in piglets

Anoxic stress attenuates NMDA-induced pial arteriolar dilation via a mechanism involving actions of cyclooxygenase (COX)-derived reactive oxygen species (ROS). We examined whether the selective COX-2 inhibitor NS398 would protect neuronal function after global hypoxia/ischemia (H/I) in piglets. Pial arteriolar responses to NMDA (10-100 micromol/l) were determined using intravital microscopy in anesthetized piglets before and 1 h after H/I. Study groups received vehicle, 0.3, 1, or 5 mg/kg NS398, or 0.3 mg/kg indomethacin (n = 7, 6, 6, 5 and 8, respectively) i.v. 20 min prior to H/I. H/I reduced NMDA- induced dilation to 44 +/- 6% (100 micromol/l NMDA, mean +/- s.e.m.) of the pre-ischemic response in vehicle animals (p < 0.05). However, NS398 dose-dependently protected arteriolar dilation to NMDA (77 +/- 8, 81 +/- 16, and 102 +/- 10% preservation at 0.3, 1 and 5 mg/kg, respectively). Indomethacin caused similar preservation. However, indomethacin but not NS398 reduced serum thromboxane B(2) levels to undetectable values. In conclusion, COX-2 appears to be a major source of ROS in the piglet cerebral cortex after H/I.

Placental transfer of SR49059 in the human dually perfused cotyledon in vitro

SR49059 is an antagonist of vasopressin V(1a)receptors currently developed as a tocolytic drug. We investigated the transplacental transfer of SR49059 in vitro using the single pass dually perfused human cotyledon model. Thirteen placentae were collected from normal term pregnancies immediately after delivery. The placental transfer of SR49059 was tested at steady state at three different concentrations (100 ng/ml, 200 ng/ml and 500 ng/ml) along with that of antipyrine 20 mg/l as a reference substance. Concentrations were assayed by liquid chromatography with UV (antipyrine) or mass spectrometry (SR49059) detection. At steady state, the mean+/-s.d. fetal transfer rate of SR49059 was 10.80+/-4.33 per cent, 9.34+/-4.41 per cent, and 11.78+/-3.26 per cent at 100 ng/ml, 200 ng/ml and 500 ng/ml, respectively. The corresponding clearance indices were 0.29+/-0.14, 0.25+/-0.08, and 0.31+/-0.06, respectively. The absence of saturation kinetics is consistent with a passive mechanism of transfer. Moderate amounts of SR49059 are transferred from the maternal to the fetal circulation. The clearance index of SR49059 appeared to be very similar to that of ritodrine, which is currently used as a tocolytic.

Effects of conjugated linoleic acids and docosahexaenoic acid on rat liver and reproductive tissue fatty acids, prostaglandins and matrix metalloproteinase production

Long chain n-6 and n-3 fatty acids play important roles in labor and delivery. These effects may be mediated by prostaglandin (PG) synthesis and by regulation of matrix metalloproteinases (MMPs), both of which play roles in uterine contraction, cervical ripening and rupture of fetal membranes. The effects of altering dietary n-6:n-3 long chain fatty acid ratios, and the addition of dietary conjugated linoleic acids (CLA) and docosahexaenoic acid (DHA) on fatty acid composition of reproductive tissues, PG synthesis in liver and reproductive tissue and serum MMP levels were examined in pregnant rats. Modified AIN-96G diets with n-6:n-3 ratios of 7:1 and 34:1 with and without added 1.1% (by weight) conjugated linoleic acid (CLA) and/or 0.3% (by weight) DHA were fed through day 20 of gestation. Reproductive tissues readily incorporated both DHA and CLA. CLA significantly (P<0.05) depressed PGF(2 alpha)synthesis in placenta, uterus and liver by 50% when the n-6:n-3 ratio was 7:1 and by 66% at 34:1 ratio. Significant differences (P<0.05) in PGE(2)synthesis in uterus and liver were seen only between groups fed the high ratio of n-6:n-3 without CLA, and the low ratio with CLA. Addition of CLA to DHA containing diets depressed PGF(2alpha) by one-third in uterus and liver (P<0.05). Serum MMP-9 and active MMP-2 were suppressed (P<0.05) by addition of either CLA or DHA.

New insights into physiological and pathophysiological functions of cyclo-oxygenase-2

During the past few years specific inhibitors of the cyclo-oxygenase-2 enzyme have emerged as important pharmacological tools for treatment of patients with rheumatoid arthritis or osteoarthritis. In comparison to traditional nonsteroidal anti-inflammatory drugs, specific cyclo-oxygenase-2 inhibitors may provide equal efficacy in terms of antiinflammatory and analgesic action, with significantly fewer gastrointestinal side effects. Although cyclo-oxygenase-2 was once regarded as a source of pathological prostanoids, recent studies have indicated that this isoenzyme also fulfills a variety of physiological functions within the organism. The present review assesses recent advances in cyclo-oxygenase-2 research, with particular emphasis on new insights into the biology of this isoenzyme.