Role of nitric oxide in the uterus and cervix: implications for the management of labor

Raspberry Leaves and Extracts-Molecular Mechanism of Action and Its Effectiveness on Human Cervical Ripening and the Induction of Labor

The gestational period is an incredibly stressful time for a pregnant woman. Pregnant patients constantly seek effective and reliable compounds in order to achieve a healthy labor. Nowadays, increasing numbers of women use herbal preparations and supplements during pregnancy. One of the most popular and most frequently chosen herbs during pregnancy is the raspberry leaf (Rubus idaeus). Raspberry extracts are allegedly associated with a positive effect on childbirth through the induction of uterine contractions, acceleration of the cervical ripening, and shortening of childbirth. The history of the consumption of raspberry leaves throughout pregnancy is vast. This review shows the current status of the use of raspberry leaves in pregnancy, emphasizing the effect on the cervix, and the safety profile of this herb. The majority of women apply raspberry leaves during pregnancy to induce and ease labor. However, it has not been possible to determine the exact effect of using raspberry extracts on the course of childbirth and the perinatal period. Additionally, it is unclear whether this herb has only positive effects. The currently available data indicate a weak effect of raspberry leaf extracts on labor induction and, at the same time, their possible negative impact on cervical ripening.

The Efficacy of Misoprostol Vaginal Inserts for Induction of Labor in Women with Very Unfavorable Cervices

BACKGROUND

The purpose of the present study was to evaluate the effectiveness of a misoprostol vaginal insert as an induction-of-labor (IOL) agent in women with an unfavorable cervix (Bishop score < 2) in achieving vaginal delivery (VD) within 48 h, depending on the gestational week, with particular emphasis on the cesarean section (CS) percentage, intrapartum analgesia application and possible side effects, such as tachysystole ratio.

METHODS

In this retrospective observational study involving 6000 screened pregnant patients, 190 women (3%) fulfilled the study inclusion criteria and underwent vaginal misoprostol IOL. The pregnant women were collected into three groups: patients who delivered at up to 37 weeks of gestation (<37 Group)-42 patients; patients who delivered between 37 and 41 weeks of gestation (37-41 Group)-76 patients; and patients who delivered after 41 weeks of gestation (41+ Group)-72 patients. The outcomes included time to delivery and mode of delivery, rate of tachysystole, need for intrapartum analgesia, and need for oxytocin augmentation.

RESULTS

Most of the patients delivered vaginally (54.8% in <37 Group vs. 57.9% in 37-41 Group vs. 61.1% in 41+ Group). A total of 89.5% (170/190) of patients delivered within 48 h (<37 Group-78.6% vs. 37-41 Group-89.5% vs. 41+ Group-95.8%). Statistical significance was demonstrated for the increased rate of vaginal deliveries and shortened time to delivery in the 41+ weeks group (p = 0.0026 and p = 0.0038). The indications for cesarean section were as follows: abnormal CTG pattern vs. lack of labor progression: 42.1% vs. 57.9% in <37 Group, 59.4% vs. 40.6% in 37-41 Group and 71.4% vs. 28.6% in 41+ Group. Statistical significance was demonstrated for the increased rate of abnormal CTG patterns as cesarean section indications in the 41+ Group (p = 0.0019). The need for oxytocin augmentation in each group was: 35.7% in <37 Group vs. 19.7% in 37-41 Group vs. 11.1% in 41+ Group. Statistical significance was shown for decreased need for oxytocin augmentation in +41 Group (p = 0.0016). The need for intrapartum anesthesia, depending on the group, was: 78.6% in <37 Group vs. 82.9% in 37-41 Group vs. 83.3% in 41+ Group. Statistical significance was demonstrated for increased need for intrapartum anesthesia application during labor in +41 Group (p = 0.0018). The prevalence of hyperstimulation was similar in all three groups (4.8% vs. 7.9% vs. 5.6% p > 0.05).

CONCLUSIONS

The misoprostol vaginal regimen for IOL used in our study is effective in achieving vaginal delivery within 48 h. In post-term women, the use of this regimen is characterized by an increased rate of vaginal deliveries, a shorter time to delivery and a lower need for oxytocin.

Signaling Pathways Regulating Human Cervical Ripening in Preterm and Term Delivery

At the end of gestation, the cervical tissue changes profoundly. As a result of these changes, the uterine cervix becomes soft and vulnerable to dilation. The process occurring in the cervical tissue can be described as cervical ripening. The ripening is a process derivative of enzymatic breakdown and inflammatory response. Therefore, it is apparent that cervical remodeling is a derivative of the reactions mediated by multiple factors such as hormones, prostaglandins, nitric oxide, and inflammatory cytokines. However, despite the research carried out over the years, the cellular pathways responsible for regulating this process are still poorly understood. A comprehensive understanding of the entire process of cervical ripening seems crucial in the context of labor induction. Greater knowledge could provide us with the means to help women who suffer from dysfunctional labor. The overall objective of this review is to present the current understanding of cervical ripening in terms of molecular regulation and cell signaling.

Impact of Oxidative Stress on Molecular Mechanisms of Cervical Ripening in Pregnant Women

Uterine cervix is one of the essential factors in labor and maintaining the proper course of pregnancy. During the last days of gestation, the cervix undergoes extensive changes manifested by transformation from a tight and rigid to one that is soft and able to dilate. These changes can be summarized as “cervical ripening”. Changes in the cervical tissue can be referred to as remodeling of the extracellular matrix. The entire process is the result of a close relationship between biochemical and molecular pathways, which is strictly controlled by inflammatory and endocrine factors. When the production of reactive oxygen species exceeds the antioxidant capacity, oxidative stress occurs. A physiologic increase of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is observed through pregnancy. ROS play important roles as second messengers in many intracellular signaling cascades contributing to the course of gestation. This review considers their involvement in the cervical ripening process, emphasizing the molecular and biochemical pathways and the clinical implications.

Spontaneous preterm birth: Involvement of multiple feto-maternal tissues and organ systems, differing mechanisms, and pathways

Survivors of preterm birth struggle with multitudes of disabilities due to improper in utero programming of various tissues and organ systems contributing to adult-onset diseases at a very early stage of their lives. Therefore, the persistent rates of low birth weight (birth weight < 2,500 grams), as well as rates of neonatal and maternal morbidities and mortalities, need to be addressed. Active research throughout the years has provided us with multiple theories regarding the risk factors, initiators, biomarkers, and clinical manifestations of spontaneous preterm birth. Fetal organs, like the placenta and fetal membranes, and maternal tissues and organs, like the decidua, myometrium, and cervix, have all been shown to uniquely respond to specific exogenous or endogenous risk factors. These uniquely contribute to dynamic changes at the molecular and cellular levels to effect preterm labor pathways leading to delivery. Multiple intervention targets in these different tissues and organs have been successfully tested in preclinical trials to reduce the individual impacts on promoting preterm birth. However, these preclinical trial data have not been effectively translated into developing biomarkers of high-risk individuals for an early diagnosis of the disease. This becomes more evident when examining the current global rate of preterm birth, which remains staggeringly high despite years of research. We postulate that studying each tissue and organ in silos, as how the majority of research has been conducted in the past years, is unlikely to address the network interaction between various systems leading to a synchronized activity during either term or preterm labor and delivery. To address current limitations, this review proposes an integrated approach to studying various tissues and organs involved in the maintenance of normal pregnancy, promotion of normal parturition, and more importantly, contributions towards preterm birth. We also stress the need for biological models that allows for concomitant observation and analysis of interactions, rather than focusing on these tissues and organ in silos.

Mid-pregnancy maternal blood nitric oxide-related gene and miRNA expression are associated with preterm birth

Aim: The nitric oxide (NO) pathway modulates inflammation and may influence birth timing. Patients & methods: Case-control analysis of 136 pregnant women with RNA obtained <28 weeks; n = 212 mRNAs and n = 108 miRNAs in the NO pathway were evaluated. NO-pathway mRNA and miRNA transcript counts in women delivering preterm versus at term were compared, miRNA-mRNA expression levels correlated and prediction models generated. Results: Fourteen genes were differentially expressed in women delivering <37 weeks; 13/14 were also differentially expressed in those delivering <34 weeks (q <0.10) versus term births. Multiple miRNA-mRNA pairs were correlated. Models with gene expression better predicted prematurity than models with only clinical or nongenomic predictors. Conclusion: Maternal blood NO pathway-related mRNA and miRNA expression is associated with prematurity.

Effect of prematurity on genome wide methylation in the placenta

Background

Preterm birth is a significant clinical problem and an enormous burden on society, affecting one in eight pregnant women and their newborns. Despite decades of research, the molecular mechanism underlying its pathogenesis remains unclear. Many studies have shown that preterm birth is associated with health risks across the later life course. The “fetal origins” hypothesis postulates that adverse intrauterine exposures are associated with later disease susceptibility. Our recent studies have focused on the placental epigenome at term. We extended these studies to genome-wide placental DNA methylation across a wide range of gestational ages. We applied methylation dependent immunoprecipitation/DNA sequencing (MeDIP-seq) to 9 placentas with gestational age from 25 weeks to term to identify differentially methylated regions (DMRs).

Results

Enrichment analysis revealed 427 DMRs with nominally significant differences in methylation between preterm and term placentas (p < 0.01) and 21 statistically significant DMRs after multiple comparison correction (FDR p < 0.05), of which 62% were hypo-methylated in preterm placentas vs term placentas. The majority of DMRs were in distal intergenic regions and introns. Significantly enriched pathways identified by Ingenuity Pathway Analysis (IPA) included Citrulline-Nitric Oxide Cycle and Fcy Receptor Mediated Phagocytosis in macrophages. The DMR gene set overlapped placental gene expression data, genes and pathways associated evolutionarily with preterm birth.

Conclusion

These studies form the basis for future studies on the epigenetics of preterm birth, “fetal programming” and the impact of environment exposures on this important clinical challenge.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0835-6) contains supplementary material, which is available to authorized users.

Changes in Cervical Nitric Oxide Concentration Correlate With Bishop Score and Cervical Length Modifications in Prostaglandin E2-Mediated Induction of Labor

OBJECTIVE

Nitric oxide (NO) plays a fundamental role in cervical ripening and it is synthesized in the human cervix. We studied the effect of the dinoprostone on cervical NO release in pregnant women, and we investigated the relationship between cervical NO metabolites, cervical length, and Bishop score.

METHODS

Seventy-seven women underwent induction of labor at > or = 37 weeks of gestation, due to post-term pregnancy (23.8%), oligohydramnios (36.3) or preeclampsia (29.9%). Cervical fluid samples for NO metabolites (NOx), Bishop score, and cervical length were assessed immediately before (time 0 [T0]) and 6 hours after (T6) the local application of dinoprostone, a commercially available prostaglandin E2 (PGE2) analog.

RESULTS

The mean patients' age was 34 +/- 3.2 years, mean gestational age at enrollment was 284 +/- 9.2 days, and nulliparous represented 31.2% of the study population. At time 0, Bishop score was less than 4 in 74% (57/77) of the subjects, mean cervical length was 28.6 +/- 5.8 mm, mean NOx concentration was 208.6 +/- 103.8 microM/mL; 6 hours later, at T6, the mean cervical length decreased to 19.5 +/- 8.8 mm, and the mean NOx concentration increased up to 316.7 +/- 240.9 microM/mL. Data were unaffected by parity or by regular uterine contraction patterns. A statistically significant positive correlation was found between changes in cervical NOx levels and Bishop score modification (P < .01; r = .494), as well as between the modification of NO metabolites concentration and cervical shortening (P < .01; r = .307).

CONCLUSIONS

Prostaglandin (PG)-induced cervical ripening is associated with local NO release. NO plays an active role in cervical remodeling since it positively correlates with both cervical shortening and Bishop score increase. NO oxide and PG are the two pathways that, cross activating each other, trigger the cascade of events responsible of cervical ripening.

Cervical dilation before first-trimester surgical abortion (<14 weeks' gestation)

First-trimester surgical abortion is a common, safe procedure with a major complication rate of less than 1%. Cervical dilation before suction abortion is usually accomplished using tapered mechanical dilators. Risk factors for major complications in the first trimester include increasing gestational age and provider inexperience. Cervical priming before first-trimester surgical abortion has been studied using osmotic dilators and pharmacologic agents, most commonly misoprostol. Extensive data demonstrate that a variety of agents are safe and effective at causing preoperative cervical softening and dilation; however, given the small absolute risk of complications, the benefit of routine use of misoprostol or osmotic dilators in first-trimester surgical abortion is unclear. Although cervical priming results in reduced abortion time and improved provider ease, it requires a delay of at least 1 to 3 h and may confer side effects. The Society of Family Planning does not recommend routine cervical priming for first-trimester suction abortion but recommends limiting consideration of cervical priming for women at increased risk of complications from cervical dilation, including those late in the first trimester, adolescents and women in whom cervical dilation is expected to be challenging.

Effects of thyroid hormones on the antioxidative status in the uterus of young adult rats

Thyroid hormones and oxidative stress play significant roles in the normal functioning of the female reproductive system. Nitric oxide (NO), a free radical synthesized by nitric oxide synthases (NOS), participates in the regulation of thyroid function and is also a good biomarker for assessment of the oxidative stress status. Therefore, the purpose of this study was to investigate effects of thyroid hormones on uterine antioxidative status in young adult rats. Thirty immature female Sprague-Dawley rats were randomly divided into three groups: control, hypothyroid (hypo-T) and hyperthyroid (hyper-T). The results showed the body weights decreased significantly in both the hypo-T and hyper-T groups and that uterine weights were decreased significantly in the hypo-T group. The serum concentrations of total triiodothyronine (T3) and thyroxine (T4), as well as estradiol (E2), were significantly decreased in the hypo-T group, but increased in the hyper-T group. The progesterone (P4) concentrations in the hypo- and hyperthyroid rats markedly decreased. Immunohistochemistry results provided evidence that thyroid hormone nuclear receptor α/β (TRα/β) and three NOS isoforms were located in different cell types of rat uteri. The NO content and total NOS and inducible NOS (iNOS) activities were markedly diminished in the hypo-T group but increased in the hyper-T group. Moreover, the activities of both glutathione peroxidase (GSH-Px) and catalase (CAT) exhibited significant decreases and increases in the hypo-T and hyper-T groups, respectively. The malondialdehyde (MDA) contents in both the hypo-T and hyper-T groups showed a significant increase. Total superoxide dismutase (T-SOD) activity in the hypo- and hyper-T rats markedly decreased. In conclusion, these results indicated that thyroid hormones have an important influence on the modulation of uterine antioxidative status.

Comparison between nitroglycerin dermal patch and nifedipine for treatment of preterm labor: a randomized clinical trial

OBJECTIVE

Preterm labor and delivery are of the most important complications of pregnancy and have a major role in neonatal mortality and morbidity. Management of preterm labor and prevention from preterm delivery in order to lower these risks have always been under serious concern. The purpose of this study was to compare the effect of nifedipine and nitroglycerin (NG) dermal patch for taking control of preterm labor.

STUDY DESIGN

The study was performed as a randomized clinical trial on women who had been admitted in the hospital diagnosed with preterm labor. In one group, the NG dermal patch and in the other group, nifedipine was prescribed. Then the women of the two groups were followed up to delivery and were compared according to arrest of labor for 2 h, 48 h, 7 days, gestational age at the time of delivery and their adverse effects. The primary outcome was to postpone delivery for 48 h in order to have enough time for prescribing corticosteroids

RESULT

The women of the two groups did not have any significant difference according to age, body mass index, primary Bishop Score, gestational age at the time of tocolytic therapy, history of abortion, vaginal or cesarean delivery and preterm labor. In more women in the NG group, delivery was postponed for 2 h (59 (98.3%) vs 48 (80%), P=0.001), for 48 h (52 women (86.7%) vs 41(68.3%), P=0.016) and also for 7 days (47 (78.3%) vs 37 (61.7%), P=0.046), than the women in the nifedipine group. Gestational age at the time of delivery was higher in the NG group (35.6±1.9 vs 34.3±2.05 weeks, P=0.155), however, it was not statistically significant. Apgar score of minute 5, (P=0.03) and neonatal weight (P=0.04), were more and cesarean deliveries, neonatal intensive care unit (NICU) admission and duration of NICU stay were less in the NG group. Adverse effects were similar, minimal and negligible in both groups.

CONCLUSION

The NG patch is a more effective method for preterm labor control than nifedipine with regard to minimal side effects.

Cell-specific expression and immunolocalization of nitric oxide synthase isoforms and soluble guanylyl cyclase α and β subunits in postnatal porcine uteri

The aim of the present study was to investigate the cellular expression and immunolocalization of nitric oxide synthase (NOS) isoforms and soluble guanylyl cyclase (sGC) subunits in postnatal porcine uteri. Immunohistochemical experiments showed that three isoforms of NOS were mainly localized in the uterine luminal and glandular epithelium and myometrium, and the intensity of immunostaining for iNOS and eNOS was increased gradually with temporal development of the postnatal uterus. In addition, sGC subunits, sGCα1 and β, were present in the uterine luminal and glandular epithelium, myometrium and stromal cells. The uterine NOS activity data showed that the total NOS and iNOS activities were significantly increased at postnatal days 21 and 35. Although constitutive NOS activity was increased at postnatal day 21, it decreased subsequently at postnatal day 35. Immunoblot analysis revealed that iNOS protein expression was significantly increased at postnatal days 21 and 35. Furthermore, sGCα1 protein expression was not significantly changed throughout days 7 to 35. Collectively, our findings suggest that NO/cGMP signaling is involved in the process of postnatal porcine uterine development.

Characterization of the myometrial transcriptome in women with an arrest of dilatation during labor

OBJECTIVE

The molecular basis of failure to progress in labor is poorly understood. This study was undertaken to characterize the myometrial transcriptome of patients with an arrest of dilatation (AODIL).

STUDY DESIGN

Human myometrium was prospectively collected from women in the following groups: (1) spontaneous term labor (TL; n=29) and (2) arrest of dilatation (AODIL; n=14). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated Student's t-test and false discovery rate adjustment were used for analysis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) of selected genes was performed in an independent sample set. Pathway analysis was performed on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database using Pathway Analysis with Down-weighting of Overlapping Genes (PADOG). The MetaCore knowledge base was also searched for pathway analysis.

RESULTS

(1) Forty-two differentially expressed genes were identified in women with an AODIL; (2) gene ontology analysis indicated enrichment of biological processes, which included regulation of angiogenesis, response to hypoxia, inflammatory response, and chemokine-mediated signaling pathway. Enriched molecular functions included transcription repressor activity, heat shock protein (Hsp) 90 binding, and nitric oxide synthase (NOS) activity; (3) MetaCore analysis identified immune response chemokine (C-C motif) ligand 2 (CCL2) signaling, muscle contraction regulation of endothelial nitric oxide synthase (eNOS) activity in endothelial cells, and triiodothyronine and thyroxine signaling as significantly overrepresented (false discovery rate <0.05); (4) qRT-PCR confirmed the overexpression of Nitric oxide synthase 3 (NOS3); hypoxic ischemic factor 1A (HIF1A); Chemokine (C-C motif) ligand 2 (CCL2); angiopoietin-like 4 (ANGPTL4); ADAM metallopeptidase with thrombospondin type 1, motif 9 (ADAMTS9); G protein-coupled receptor 4 (GPR4); metallothionein 1A (MT1A); MT2A; and selectin E (SELE) in an AODIL.

CONCLUSION

The myometrium of women with AODIL has a stereotypic transcriptome profile. This disorder has been associated with a pattern of gene expression involved in muscle contraction, an inflammatory response, and hypoxia. This is the first comprehensive and unbiased examination of the molecular basis of an AODIL.

Vaginal progesterone vs. cervical cerclage for the prevention of preterm birth in women with a sonographic short cervix, previous preterm birth, and singleton gestation: a systematic review and indirect comparison metaanalysis

OBJECTIVE

No randomized controlled trial has compared vaginal progesterone and cervical cerclage directly for the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous spontaneous preterm birth. We performed an indirect comparison of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator.

STUDY DESIGN

Adjusted indirect metaanalysis of randomized controlled trials.

RESULTS

Four studies that evaluated vaginal progesterone vs placebo (158 patients) and 5 studies that evaluated cerclage vs no cerclage (504 patients) were included. Both interventions were associated with a statistically significant reduction in the risk of preterm birth at <32 weeks of gestation and composite perinatal morbidity and mortality compared with placebo/no cerclage. Adjusted indirect metaanalyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Based on state-of-the-art methods for indirect comparisons, either vaginal progesterone or cerclage are equally efficacious in the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous preterm birth. Selection of the optimal treatment needs to consider adverse events, cost and patient/clinician preferences.

Endocrinology of parturition

The myometrium must remain relatively quiescent during pregnancy to accommodate growth and development of the feto-placental unit, and then must transform into a highly coordinated, strongly contracting organ at the time of labour for successful expulsion of the new born. The control of timing of labour is complex involving interactions between mother, fetus and the placenta. The timely onset of labour and delivery is an important determinant of perinatal outcome. Both preterm birth (delivery before 37 week of gestation) and post term pregnancy (pregnancy continuing beyond 42 weeks) are both associated with a significant increase in perinatal morbidity and mortality. There are multiple paracrine/autocrine events, fetal hormonal changes and overlapping maternal/fetal control mechanisms for the triggering of parturition in women. Our current article reviews the mechanisms for uterine distension and reduced contractions during pregnancy and the parturition cascade responsible for the timely and spontaneous onset of labour at term. It also discusses the mechanisms of preterm labour and post term pregnancy and the clinical implications thereof.

High iNOS mRNA and protein localization during late pregnancy suggest a role for nitric oxide in mouse pubic symphysis relaxation

Remodeling and relaxation of the mouse pubic symphysis (PS) are central events in parturition. The mouse PS remodels in a hormone-controlled process that involves the modification of the fibrocartilage into an interpubic ligament (IpL), followed by its relaxation prior to parturition. It is recognized that nitric oxide synthase (NOS) and consequently nitric oxide (NO) generation play important roles in extracellular matrix modification, and may promote cytoskeleton changes that contribute to the remodeling of connective tissue, which precedes the onset of labor. To our knowledge, no studies thus far have investigated inducible nitric oxide synthase (iNOS) expression, protein localization, and NO generation in the mouse PS during pregnancy. In this work, we used a combination of the immunolocalization of iNOS, its relative mRNA expression, and NO production to examine the possible involvement of iNOS in remodeling and relaxation of the mouse IpL during late pregnancy. The presence of iNOS was observed in chondrocytes and fibroblast-like cells in the interpubic tissues. In addition, iNOS mRNA and NO production were higher during preterm labor on Day 19 of pregnancy (D19) than NO production on D18 or in virgin groups. The significant increase in iNOS mRNA expression and NO generation from the partially relaxed IpL at D18 to the completely relaxed IpL at D19 may indicate that NO plays an important role in late pregnancy during relaxation of the mouse IpL.

A collaboration of aquaporins handles water transport in relation to the estrous cycle in the bitch uterus

Fluid movement through uterine cell membranes is crucial, as it can modulate the tissue imbibition pattern in the different phases of the estrous cycle. To gain insight into the mechanisms underlying steroid-controlled water handling, the presence and distribution of aquaporins (AQPs), integral membrane channel proteins permitting rapid passive water movement, was explored in bitch uterine tissues. Immunohistochemistry and Western immunoblot analysis were used to study the presence of AQP1, AQP2, and AQP5 in the layers of the bitch uterine wall during the different estrous phases. Presence of endothelial nitric oxide-generating enzyme NO synthase (NOS3) was also investigated, as it is known that the vasodilator NOS3 might be involved in the development of uterine edema. The results demonstrated the following: (1) AQP1, AQP2, and AQP5 were present in the uterus of cycling bitches. (2) AQP1 was localized within uterine mesometrial, myometrial, and endometrial blood vessels and in the circular and longitudinal layers of myometrium. AQP1 localization and expression were unaffected by the estrous cycle. (3) The estrogenic milieu was probably at the basis of AQP2 expression in the glandular and luminal epithelium of the endometrium. (4) AQP5 water channels were present in the apical plasma membrane of uterine epithelial cells in coincidence with plasma progesterone increase. (5) NOS3 was localized in the myometrial and epithelial tissues as well as in blood vessels indicating a contribution of this vasoactive peptide to the uterine imbibition processes. Thus, we can hypothesize that a functional and distinctive collaboration exists among diverse AQPs in water handling during the different functional uterine phases.

Nitric oxide detection by DAF (diaminofluorescein) fluorescence in human myometrial tissue

Nitric oxide (NO) is considered to be involved in the modulation of uterine contractility. In the present pilot study, the direct detection of intracellular NO in pregnant human myometrial tissues has been investigated by using the fluorescent indicator 4,5-diaminofluorescein-2 diacetate (DAF-2DA). Pregnant myometrial tissue samples were obtained during Cesarean sections between week 34 and 40 of gestation before the onset of labor. Living explants were loaded with 10 microM DAF-2DA, stimulated with 1 mM arginine, subsequently fixed with glutaraldehyde and examined by fluorescence microscopy. The presence of NO synthases (NOS) was studied by immunohistochemistry. After application of DAF-2DA, DAF fluorescence was located primarily in blood vessels and to a minor extent in myometrial cells. By immunohistochemistry, strong endothelial NOS (eNOS) staining was found in vessel walls. In myometrial cells weak staining of eNOS and inducible NOS was observed. We conclude that the direct NO detection by DAF-2DA provides a new and independent method to identify sites of NO production in myometrium and other heterogeneous tissues.

Nitric oxide in the human uterine cervix: endogenous ripening factor

The human uterine cervix can produce nitric oxide (NO), a free radical with an ultra-short half-life. The release of NO changes during pregnancy and is increased in early nonviable pregnancies compared to normal uncomplicated pregnancies. This review concentrates on the role of NO release in cervical ripening in pregnant women. Also some suggestions on future aspects are discussed.

Nitric oxide metabolite levels in preterm labor

AIM

To investigate the role of nitric oxide metabolites as markers of infection in subjects with preterm labor or preterm premature rupture of membranes (PTPROM). PTPROM means that there was spontaneous rupture of fetal membrane before the onset of labor and gestational age was <37 weeks. This occurs because of imbalance between matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase. The cause of this imbalance that leads to degradation of collagen causing PTPROM is infection. The bactericidal, fungicidal, viricidal and tumoricidal activities of macrophages are determined in part by elaboration of nitric oxide, hence nitric oxide levels have been found to be increased in infections.

METHODS

During an 18-month period 50 women with preterm labor or PTPROM and 50 controls were enrolled prospectively. Blood and urine samples were obtained for analysis of nitric oxide metabolites. Patients with known causes of preterm labor were excluded.

RESULT

The nitric oxide metabolites, which included both nitrite levels and citrulline levels were significantly higher both in blood as well as urine in patients with preterm labor and PTPROM compared to controls. Serum nitrite levels in subjects with preterm labor were 376.5 +/- 345 nmol/L while in subjects with PTPROM they were 295.7 +/- 161.1 nmol/L and in controls the levels were 62.7 +/- 33.9 nmol/L. Serum citrulline levels in subjects with preterm labor were 5293.8 +/- 2916.7 nmol/L; in PTPROM they were 6536.6 +/- 609.91 nmol/L and in controls they were 949.8 +/- 67.1 nmol/L. On comparing patients with preterm labor, those in whom preterm labor could not be inhibited had statistically significant higher levels of nitrite in both serum and urine (482.9 +/- 387.7 nmol/L and 754.5 +/- 336.5 nmol/L, respectively) compared to patients in whom labor could be inhibited (172.2 +/- 61.9 nmol/L and 401.8 +/- 236.9 nmol/L, respectively). The citrulline levels were also higher among the group who delivered preterm for both serum and urine (5355.4 +/- 3229.7 nmol/L and 11 482.8 +/- 2541.4 nmol/L, respectively) compared to patients in whom labor could be inhibited (5260.2 +/- 2897.08 nmol/L and 10 651.4 +/- 1502.7 nmol/L, respectively) but this did not reach statistical significance.

CONCLUSION

Higher nitric oxide metabolites in women with preterm labor are marker of subclinical infection.

Isosorbide mononitrate vaginal gel versus misoprostol vaginal gel versus Dilapan-S for cervical ripening before first trimester curettage

OBJECTIVE

To compare the efficacy and safety of vaginal applications of three different principles of cervical priming prior to first trimester curettage, isosorbide mononitrate (ISMN), misoprostol and Dilapan-S, a hygroscopical cervical dilator.

STUDY DESIGN

Pregnant women with missed abortion between 6 and 12 gestational weeks were included and randomly assigned to receive either 80 mg ISMN vaginal gel (group 1) or 200 microg of misoprostol vaginal gel (group 2) or Dilapan-S, a hygroscopical cervical dilator (group 3), for cervical ripening before curettage. Outcome parameters were cervical dilation at the time of operation and maximum dilation reached with Hegar's dilator and the degree of difficulty in mechanical dilation as well as safety and side effects of the preparations.

RESULTS

Sixty-five pregnant women with missed abortion were included and assigned to the three study groups (n=22 for group 1, n=22 for group 2, n=21 for group 3). Misoprostol vaginal gel and Dilapan-S were significantly more effective than ISMN vaginal gel in cervical dilation reached with priming (p<0.005 and p<0.005) and in the degree of difficulty in cervical dilation assessed by the surgeon (p<0.001 and p<0.01). Mild discomfort was indicated by all patients after Dilapan insertion, whereas no patient complained about discomfort after misoprostol or ISMN insertion (p<0001). Three patients suffered from mild hypotension and headache after ISMN treatment, and two had increased vaginal bleeding due to uterine atony during surgery (p<0.05).

CONCLUSION

A vaginal gel of ISMN is less effective for cervical ripening prior to first trimester curettage compared to misoprostol vaginal gel or Dilapan-S. The latter could be an effective and safe alternative to prostaglandin priming avoiding preoperative contractions caused by prostaglandin preparations.

Clinical use of nitric oxide donors and L-arginine in obstetrics

Nitric oxide (NO) is a free radical that plays a fundamental role in human physiology, being involved in the homeostasis of different functions. In obstetrics this molecule is determinant in the physiology of labor and cervical ripening; it possibly plays a fundamental role in the etiology of preeclampsia and intrauterine growth restriction, and it could also be utilized in view of its ability to induce smooth muscle relaxation. Several clinical trials have ascertained the ability of the topical application of NO donors to promote cervical ripening, and also labor induction. There is much less evidence on the use of NO donors in the vascular complications of pregnancy, either as prophylactics or therapeutic agents. Due to the capacity of NO to promote relaxation of smooth muscle, NO donors have been employed as tocolytics with performance similar to other agents. Moreover, although anecdotal, the experience of sudden uterine relaxation using NO donors in obstetric emergencies remains of great clinical value.

Association between 49 infant gene polymorphisms and preterm delivery

The occurrence of preterm delivery has been increasing in the U.S. Previous studies have identified risk factors for preterm delivery that may have genetic influences. We conducted a case-control study comparing the frequencies of 49 genetic polymorphisms among 62 preterm infants and 553 term infants. The polymorphisms that we examined were involved in xenobiotic-metabolism, blood pressure, coagulation, the inflammatory response, cell-cell interaction, or folate-homocysteine metabolism. Univariate analyses on the individual polymorphisms revealed a statistically significant effect for the variant genotypes compared to the wildtype genotypes in SERPINE1 11053G > T (OR = 0.4, 95% CI = 0.2-0.8). This finding suggests the coagulation/thrombophilic pathway may influence the development of preterm delivery.

Quantitative ultrasound assessment of the rat cervix

OBJECTIVE

The purpose of this research was to detect cervical ripening with a new quantitative ultrasound technique.

METHODS

Cervices of 13 nonpregnant and 65 timed pregnant (days 15, 17, 19, 20, and 21 of pregnancy) Sprague Dawley rats were scanned ex vivo with a 70-MHz ultrasound transducer. Ultrasound scatterer property estimates (scatterer diameter [SD], acoustic concentration [AC], and scatterer strength factor [SSF]) from the cervices were quantified and then compared to hydroxyproline and water content. Insertion loss (attenuation) was measured in 3 rats in each of the 6 groups. Discriminant analysis was used to predict gestational age group (cervical ripening) from the ultrasound variables SD, SSF, and AC.

RESULTS

Differences were observed between the groups (SD, AC, and SSF; P < .0001). Quantitative ultrasound measures changed as the cervix ripened: (1) SD increased from days 15 to 21; (2) AC decreased from days 15 to 21; and (3) SSF was the greatest in the nonpregnant group and the least in the day 21 group. Cervix hydroxyproline content increased as pregnancy progressed (P < .003) and correlated with group, SD, AC, and SSF (P < .001). Discriminant analysis of ultrasound variables predicted 56.4% of gestational group assignment (P < .001) and increased to 77% within 2 days of the predicted analysis. Cervix insertion loss was greatest for the nonpregnant group and least for the day 21 group.

CONCLUSIONS

Quantitative ultrasound predicted cervical ripening in the rat cervix, but before use in humans, quantitative ultrasound will need to predict gestational age in the later days of gestation with more precision.

Hormonal regulation of placental nitric oxide and pathogenesis of pre-eclampsia

The placenta is central to foetal growth and development in mammalian pregnancy. Compromised placental function (as found in pre-eclampsia) often results in life-threatening situations for both mother and foetus. The nitric-oxide (NO) signalling cascade is important for placental function, in particular for the development of the vascular network and for maintaining vascular tone. This pathway seems to be regulated by multiple hormonal signals. Emerging evidence suggests that pathogenic mechanisms that are involved in abnormal placental function target specific molecules, such as hormone receptors, that regulate NO release and have subsequent dramatic consequences. Here, we discuss the current knowledge of NO function in the placenta, its hormonal regulation in normal pregnancy and in the pathophysiology of pre-eclampsia, its potential pathogenic mechanisms and possible use as a therapeutic target.

The role of cervical cerclage in obstetric practice: can the patient who could benefit from this procedure be identified?

This editorial critically examines the definition of "cervical insufficiency." The definition, the clinical ascertainment, efforts to develop an objective method of diagnosis, as well as the nature of cervical disease leading to spontaneous mid-trimester spontaneous abortion and preterm delivery are reviewed. The value and limitations of cervical sonography as a risk assessment tool for spontaneous preterm delivery are appraised. The main focus is on the role of cervical cerclage to prevent an adverse pregnancy outcome. The value of assessing the presence or absence of endocervical inflammation in the outcome of cerclage placement is discussed.

Urinary cyclic guanosine 3',5'-monophosphate and cyclic adenosine 3',5'-monophosphate changes in spontaneous and induced onset active labor

BACKGROUND

The aim of this prospective, randomized study was to investigate the changes in urinary cyclic guanosine 3',5'-monophosphate (cGMP) and cyclic adenosine 3',5'-monophosphate (cAMP) between the latent and the active phases of spontaneous and prostaglandin E(1) (PGE(1))-induced labor.

METHODS

Seventy singleton pregnant women at 36-41(+) weeks' gestation without signs of fetal distress were enrolled. The first group consisted of 35 pregnant women in whom labor was induced by PGE(1) applied intravaginally. The second group consisted of 35 women who had spontaneous active labor. Clinical data of the two groups were assessed as labor progressed.

RESULTS

After the onset of active labor, urinary cGMP/creatinine (U cGMP/Cr) decreased in both groups with the percentage decline of 35.2 and 9.7, respectively, but this difference was only significant in the PGE(1)-induced group (P=0.033). After the onset of active labor, urinary cAMP/creatinine (U cAMP/Cr) decreased in both groups with the percentage decline of 36.5 and 15.6, respectively, but this difference was only significant in the PGE(1)-induced group (P=0.001). The duration of the latent phase was significantly shortened in the PGE(1)-induced group compared with the spontaneous labor group (P<0.05).

CONCLUSIONS

Decreased U cGMP/Cr and U cAMP/Cr may be a transition from the latent to the active phase in PGE(1)-induced labor. Our results suggest that U cGMP/Cr and U cAMP/Cr can serve as easily obtained secondary messenger markers of myometrial contractility and cervical ripening at the onset of active labor. The NO-cGMP system and the G-protein alpha-cAMP system in the human uterus may concomitantly contribute to uterine quiescence during pregnancy and show downregulation in U cGMP/Cr and U cAMP/Cr at the initiation of active labor.

Unaltered innervation of the human cervix uteri in contrast to the corpus during pregnancy and labor as revealed by PGP 9.5 immunohistochemistry

OBJECTIVE

To examine the occurrence of the general neuronal marker protein gene product 9.5 (PGP 9.5) in the human corpus (isthmus region) and the cervix uteri during pregnancy and parturition

STUDY DESIGN

Biopsies were taken from the upper edge of the hysterotomy during caesarean section (CS) at term (n=5), in labor (n=5) and from the corresponding area in the non-pregnant uterus after hysterectomy (n=5). Cervical biopsies were obtained transvaginally from the anterior cervical lip. Serial cryostate sections were prepared for immunohistochemistry using polyclonal antibodies to PGP 9.5.

RESULTS

Nerve fibers displaying PGP 9.5 immunoreactivity were observed in all sections from the three groups examined. They were identified in muscle tissue, in the stroma, and around blood vessel walls. A 30-fold decline of immunoreactive nerve fibers was observed in the isthmus part of the corpus uteri at term compared to the non-pregnant. There were no significant differences between the immunoreactivity in the cervix uteri of the three groups

CONCLUSIONS

The innervation of the cervix uteri is dense and unaltered throughout pregnancy and labor. In contrast, the corpus is almost denervated. Further studies are needed to clarify the reason and the impact of these findings.

mRNA expression and localization of bNOS, eNOS and iNOS in human cervix at preterm and term labour

BACKGROUND

Preterm birth is the primary cause of the neonatal mortality and morbidity. There will be no preterm birth without a cervical softening. Nitric oxide (NO) is shown to be a mediator of term cervical ripening. The aim of this study was to investigate mRNA expression of the three isomers of NO synthases (NOS) and to identify them by immunohistochemistry in the human cervix at preterm birth compared to term.

METHODS

The three isomers of NOS--inducible (iNOS), endothelial (eNOS) and neuronal (bNOS)--were investigated in the human cervix. The expression of mRNA was determined using Real-Time Multiplex RT-PCR. The localisation of synthases in the cervical tissue was analysed using immunohistochemistry. Cervical biopsies were obtained from 4 groups of women without clinical signs of infection: preterm (PTL), term labour (TL), preterm not in labour (PTnotL) and term not in labour (TnotL) patients. One-Way ANOVA, Kruskal-Wallis, Student t-test or Mann-Whitney test were applied as appropriate to determine statistically significant differences among the groups.

RESULTS

Patients in preterm labour had significantly (p < 0.01) higher mRNA levels of all the three NOS isomers compared to those in term labour. Women not in labour, irrespective of gestational age, thus with unripe cervices, had significantly lower eNOS mRNA levels compared to those in labour (p < 0.01). Immunoreactivity for all three NO synthases was observed in each examined sample in all groups. The bNOS staining was the most prominent.

CONCLUSION

The mRNA levels were higher in the preterm labour group compared to the women at term labour. The significant increase of the eNOS mRNA expression, from the unripe to the favourable cervical state during labour, may indicate a role of eNOS and supports the role of NO in the cervical ripening process. All the three synthases were identified by immunohistochemistry in all the groups of study.

Nitric oxide as putative second messenger in nerve-induced cervical gland secretion in the guinea-pig

Uterine cervical secretory cells receive a sympathetic cholinergic secretomotor innervation. It has been suggested that glandular nitric oxide (NO) production is a prerequisite for muscarinic-induced carbohydrate secretion in the endometrium and the seminal vesicle. A similar pattern for nerve-induced carbohydrate secretion in the cervix could be assumed. Nitric oxide synthase (NOS) activity was evaluated via formation of L-citrulline from L-arginine. The NADPH-diaphorase nitroblue technique was used for histochemical investigation. The cervix with the adjacent hypogastric nerve was placed in an isolated organ bath and the secretion was evaluated as an amount of carbohydrate. A calcium-dependent formation of citrulline was found in the cervix indicating NO formation. Strong NADPH-staining cells were found in the glandular ducts and in the glandular linings of the cervix. Stimulation of the hypogastric nerve induced carbohydrate secretion, which was inhibited by N-nitro-L-arginine methyl ester (L-NAME). D-NAME did not affect the secretory response. Carbachol and the NO donor glyceryl trinitrate (GTN) induced carbohydrate secretion in the cervical glands. No synergistic effect was noted probably due to an all-or-none type of secretion. N-nitro-L-arginine (L-NNA) and L-NAME inhibited carbachol-induced secretion. The results suggest that glandular NO production is a prerequisite for the autonomic nervous modulation of cervical secretion in the guinea-pig. This could have implications regarding fertility and fecundity.

Urinary nitric oxide metabolite changes in spontaneous and induced onset active labor

BACKGROUND

The aim of this prospective, randomized study was to investigate the changes in urinary nitric oxide (NO) metabolite between the latent and the active phases of spontaneous and either prostaglandin E(1) (PGE(1)) or prostaglandin E(2) (PGE(2))-induced labors.

METHODS

Eighty-eight singleton pregnant women at 36-41(+) weeks' gestation without signs of fetal distress were enrolled. The first group consisted of 29 pregnant women in whom labor was induced by PGE(1) applied intravaginally. The second group consisted of 29 pregnant women with labor induced by PGE(2) applied intracervically. The third group consisted of 30 women, who had spontaneous active labor. Clinical data of the three groups were assessed as labor progressed.

RESULTS

Urinary nitric oxide/creatinine (U NO/Cr) decreased significantly after the onset of active labor in all three groups (p < 0.005), with the percentage decline of 42.2%, 28.6% and 10.1%, respectively. The magnitude of the difference in decline in U NO/Cr after active labor between the PGE(1)-induced and the spontaneous labor group was significantly reduced (p = 0.0047) after adjustment for potential confounders using the generalized estimating equations test (GEE). The duration of the latent phase was significantly shortened in the PGE(1)-induced group as compared with the spontaneous labor group (p < 0.01).

CONCLUSIONS

Decreased U NO/Cr may facilitate transition from the latent to the active phase either in spontaneous or induced labors. Our results indicate that U NO/Cr can serve as an easily obtained marker for use in controlling myometrial contractility and cervical ripening at the onset of active labor. The nitric oxide system is present in the human uterus and may contribute to uterine quiescence during pregnancy and show down-regulation in U NO/Cr at the initiation of active labor.

Prostaglandins and the myometrium and cervix

Prostaglandins have long been thought to play important roles in the mechanism of parturition. Here we review the involvement of prostaglandins in myometrial and cervical functions with emphasis on human labor and birth. In addition, the cellular sources of prostaglandins as well as their interactions with various other endocrine, paracrine and physical factors, such as oxytocin, corticotropin releasing hormone, nitric oxide, platelet activating factor, cytokines, endothelin and stretch are also addressed together with their potential role in the molecular reorganization of cervical structure associated with labor and delivery. Finally, the premier role of progesterone in pregnancy maintenance and parturition is juxtaposed with the proposed "fine-tuning", modulatory role of prostaglandins and the above listed factors in the regulation of parturition.

Thrombospondin 2 deficiency in pregnant mice results in premature softening of the uterine cervix

The gradual disorganization of collagen fibers in the stromal connective tissue of the uterine cervix is characteristic of progressive cervical softening during pregnancy. A lack of thrombospondin (TSP) 2 has been shown to be associated with altered collagen fibril morphology of connective-tissue-rich organs such as skin and tendon. The goal of this study was to determine the role of TSP2 in cervical softening by studying a TSP2-null mouse line. Creep testing showed that, in the nonpregnant animal and on Day 10 of pregnancy, there was no difference between the cervical extensibility of the wild-type and the TSP2-deficient mice. However, by Day 14 of pregnancy, the TSP2-null mice showed 4.5-fold increase in cervical extensibility, and by Day 18, a 6.1-fold increase, when compared with wild-type mice. A further indicator of compromised cervical integrity was that, on Days 14 and 18 of pregnancy, the cervix of TSP2-null mice broke rapidly under standard loading conditions that did not break the cervix of wild-type mice. Western blotting showed that TSP2 was expressed in the cervix of mice on Days 14 and 18 of pregnancy but not on Day 10 or in the nonpregnant animal. As determined by immunohistochemistry, the amount of matrix metalloproteinase 2 (MMP2) in the cervix of TSP2-null mice increased 11-fold on Day 14 of pregnancy and 19-fold on Day 18. Thus, TSP2-null mice provide an animal model to assist in the understanding of the molecular basis of spontaneous, premature softening of the uterine cervix.

Effects of endotoxin and macrophage-related cytokines on the contractile activity of the gravid murine uterus

Immune cell trafficking and activity are implicated in the parturition process, but little is known about the role of macrophages in control of uterine contractility at term. In the present study, we tested the hypothesis that endotoxin (lipopolysaccharide [LPS]) enhances uterine contractile activity through a mechanism that involves activation of resident macrophages. Various uterotonins and anti-inflammatory mediators were added to a standard muscle bath preparation that contained strips of uterus from Day 15 pregnant C3H/HeN mice. Spontaneous and agonist-induced contractile activity was enhanced following LPS treatment. LPS increased amplitude but not frequency of contractions. Addition of anti-inflammatory cytokines, interleukin 10 or transforming growth factor beta, to suppress macrophage activation did not block LPS-induced increases in contractility. By contrast, indomethacin given to block prostaglandin production suppressed the LPS-induced increase in amplitude of contractions. These findings suggest that an inflammatory response, possibly mediated by activation of macrophages and prostaglandins, participates in the regulation of amplitude but not frequency of contractile activity by the murine uterus before onset of parturition.

FGL2 prothrombinase messenger RNA expression in gravid and nongravid human myometrium

OBJECTIVE

Thrombin is a potent uterotonic agent that may play an important role in human parturition. FGL2 is a prothrombinase that cleaves prothrombin to thrombin. The purpose of this study was to determine FGL2 messenger RNA expression in human myometrium and to assess its relationship to the expression of EP3-6 prostaglandin receptor and inducible nitric oxide synthase.

STUDY DESIGN

Myometrium was obtained from gravid women who underwent cesarean delivery (n = 19), from premenopausal (n = 10) and menopausal (n = 10) women who underwent hysterectomy, and from nonpregnant women who received 200 mg of misoprostol vaginally 12 hours before hysterectomy (n = 8). FGL2 messenger RNA expression was determined with the use of semiquantitative polymerase chain reaction and was compared with previously determined messenger RNA expression levels for EP3-6 and inducible nitric oxide synthase for the same samples. Statistical analysis was performed with the use of independent t test, Fisher exact test, analysis of variance, and linear regression, where appropriate.

RESULTS

All samples that were analyzed contained demonstrable quantities of FGL2 messenger RNA. The highest FGL2 expression was found in gravid women, followed by women who were treated with misoprostol, by premenopausal nonpregnant women, and by menopausal women (P <.0001, analysis of variance). Significantly higher levels of FGL2 expression were found in the gravid women compared with the women who were treated with misoprostol (P <.001), the premenopausal nonpregnant women (P <.001), and the menopausal women (P <.0001). FGL2 messenger RNA expression correlated with EP3-6 and inducible nitric oxide synthase expression in all samples combined (r = 0.55, P <.0001; and r = 0.67, P <.001, respectively).

CONCLUSION

The expression of FGL2 messenger RNA is increased in gravid myometrium compared with nonpregnant samples. Its expression significantly correlates to EP3-6 and inducible nitric oxide synthase expression. FGL2 prothrombinase expression may mediate the role of thrombin in human parturition.

The expression of EP3-6 and inducible nitric oxide synthase messenger RNA are correlated in pregnant and misoprostol-treated but not in nongravid or menopausal myometrium

OBJECTIVE

Our purpose was to investigate the expression level of inducible nitric oxide synthase (iNOS) in nongravid and gravid human myometrium and assess its relation to the expression of EP3 prostaglandin receptor isoforms.

STUDY DESIGN

Myometrial tissue from a cohort of gravid, nongravid, and menopausal subjects and from nongravid subjects exposed to misoprostol was obtained and analyzed for iNOS messenger RNA (mRNA) expression and compared with previously determined mRNA levels for the EP3-6 prostaglandin receptor from the same samples by means of semiquantitative polymerase chain reaction.

RESULTS

Significantly higher levels of iNOS mRNA expression were found in the gravid compared with premenopausal nongravid (P <.02) and menopausal (P <.05,) samples. Linear regression analysis of iNOS versus EP3-6 expression showed a positive correlation between all studied samples (n = 47, P <.0001, r = 0.815). Among individual groups, a significant linear correlation was found only in pregnant (n = 10, P <.0001, r = 0.785) and misoprostol-exposed (n = 7, P =.0256, r = 0.815) subjects. No correlation between iNOS and EP3-6 mRNA levels was noted in the nongravid premenopausal groups (n = 10, P =.205, r = 0.350), although a nonsignificant trend was found for the menopausal group (n = 10, P =.0535, r = 0.624). When the data from pregnant patients were stratified, both laboring and nonlaboring women displayed the observed correlation (n = 6, P <.0001, r = 0.993; and n = 13, P =.008, r = 0.697, respectively).

CONCLUSION

iNOS and EP3-6 expression are strongly correlated in gravid and misoprostol-treated, nongravid myometrium.

Characterising the corticotropin-releasing hormone (CRH) receptors mediating CRH and urocortin actions during human pregnancy and labour

The mechanism of human labour remains unresolved. One of the most important regulatory signals, however, appears to be corticotropin-releasing hormone (CRH), a hypothalamic peptide that controls the body's response to stress, which is also produced by the placenta and intrauterine tissues during pregnancy. CRH belongs to a family of peptides that includes urocortin, which shares sequence homology with CRH and is also expressed by the placenta and intrauterine tissues. During human pregnancy circulating CRH appears to have five main target tissues: the myometrium, the placenta, the fetal membranes, the fetal adrenal cortex and the vasculature. In these tissues CRH plays a role in the control of myometrial contractility,placenta vasodilation, peptide and prostaglandin production and adrenal steroidogenesis and probably many more, yet unidentified processes. The actions of CRH in these tissues are mediated via specific G-protein coupled membrane-bound receptors. These receptors have different functional characteristics, depending on where they are expressed and on the stage of pregnancy. In addition, their function depends upon other intracellular signals via communication between signalling cascades. These findings led us to propose a hypothesis for a dual role of CRH and other CRH-like peptides during pregnancy and labour.

Nitric oxide for treatment of threatened preterm labor

OBJECTIVE

The aim of our study was the assessment of effectiveness of nitroglycerin as a donor of nitric oxide, administered in the form of transdermal therapeutic system, applied in the treatment of threatening preterm labor.

PATIENTS AND METHODS

The study was carried out on 30 pregnant patients with the symptoms of threatening preterm labor between 27th and 34th week of gestation. The patients were given nitroglycerin in the form of transdermal system releasing 5 mg of nitroglycerin in 24 h.

RESULTS

In our study the decrease in contractility and relaxation of uterus was observed in all obstetric patients. No changes in the fetal pulse rate and cardiotocographic tracing in the course of treatment and after completing treatment were observed.

CONCLUSION

Nitroglycerin in the form of transdermal therapeutic system releasing nitric oxide may be an effective and safe tocolytic drug, however, further investigation needs to be performed.

Induction of proliferative lesions of the uterus, testes, and liver in swiss mice given repeated injections of sodium arsenate: possible estrogenic mode of action

Inorganic arsenic (As) is a human carcinogen but has not been unequivocally proven carcinogenic in rodents. For instance, one older study indicates that repeated iv injections of sodium arsenate might induce lymphomas in Swiss mice (58% incidence) (Osswald and Goerttler, Verh. Dtsch. Ges. Pathol. 55, 289-293, 1971), but it was considered inadequate for critical evaluation of carcinogenic potential largely because of issues in experimental design. Therefore, we studied repeated iv sodium arsenate injection and neoplastic response in male and female Swiss mice. Groups (n = 25) of mice received sodium arsenate (0.5 mg/kg, iv) or saline (control) once/week for 20 weeks and were observed for a total of 96 weeks when the study ended. Differences in survival and body weights were unremarkable. In females, arsenate induced marked increases in the incidence and severity of cystic hyperplasia of the uterus compared against controls. Arsenate also was associated with a rare adenocarcinoma of the uterus. Hyperplastic uterine epithelium from arsenate-exposed animals showed strong positive immunostaining for the proliferating cell nuclear antigen (PCNA). There was also an upregulation of estrogen receptor (ER) immunoreactive protein in the early lesions of uterine luminal and glandular hyperplasia, although a progressive decrease in its expression was seen in the severe hyperplastic or neoplastic epithelium. In common with the preneoplastic and neoplastic gynecological lesions in humans, the levels of immunoreactive inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine-containing proteins were greater in the uterine hyperplastic epidermis and their intensity was positively correlated with the severity of the lesions. Arsenate-induced uterine hyperplastic lesions also showed a strong upregulation of cyclin D1, an estrogen-associated gene product essential for progression through the G1 phase of the cell cycle. In other tissues, arsenate increased testicular interstitial cell hyperplasia incidence and severity over control but without affecting the incidence of tubular degeneration. Arsenate also induced increases in hepatic proliferative lesions (HPL; foci of alteration + neoplasia), but only in females. Significant skin changes (incidence of hyperkeratotic lesions) and renal lesions (severity of nephropathy) also occurred in arsenate-treated females. Thus, repeated arsenate exposure, though not outright tumorigenic in the present study, was associated with proliferative, preneoplastic lesions of the uterus, testes, and liver. Estrogen treatment has been associated with proliferative lesions and tumors of the uterus, female liver, and testes in other studies, supporting a hypothesis that arsenate might somehow act through an estrogenic mode of action.