Prostacyclin and thromboxane changes predating clinical onset of preeclampsia: a multicenter prospective study

Vasodilator factors in the systemic and local adaptations to pregnancy

We postulate that an orchestrated network composed of various vasodilatory systems participates in the systemic and local hemodynamic adaptations in pregnancy. The temporal patterns of increase in the circulating and urinary levels of five vasodilator factors/systems, prostacyclin, nitric oxide, kallikrein, angiotensin-(1-7) and VEGF, in normal pregnant women and animals, as well as the changes observed in preeclamptic pregnancies support their functional role in maintaining normotension by opposing the vasoconstrictor systems. In addition, the expression of these vasodilators in the different trophoblastic subtypes in various species supports their role in the transformation of the uterine arteries. Moreover, their expression in the fetal endothelium and in the syncytiotrophoblast in humans, rats and guinea-pigs, favour their participation in maintaining the uteroplacental circulation. The findings that sustain the functional associations of the various vasodilators, and their participation by endocrine, paracrine and autocrine regulation of the systemic and local vasoactive changes of pregnancy are abundant and compelling. However, further elucidation of the role of the various players is hampered by methodological problems. Among these difficulties is the complexity of the interactions between the different factors, the likelihood that experimental alterations induced in one system may be compensated by the other players of the network, and the possibility that data obtained by manipulating single factors in vitro or in animal studies may be difficult to translate to the human. In addition, the impossibility of sampling the uteroplacental interface along normal pregnancy precludes obtaining longitudinal profiles of the various players. Nevertheless, the possibility of improving maternal blood pressure regulation, trophoblast invasion and uteroplacental flow by enhancing vasodilation (e.g. L-arginine, NO donors, VEGF transfection) deserves unravelling the intricate association of vasoactive factors and the systemic and local adaptations to pregnancy.

Pathophysiology of placentation abnormalities in pregnancy-induced hypertension

During embryogenesis and development, the fetus obtains oxygen and nutrients from the mother through placental microcirculation. The placenta is a distinctive organ that develops and differentiates per se, and that organizes fetal growth and maternal condition in the entire course of gestation. Several life-threatening diseases during pregnancy, such as pregnancy-induced hypertension (PIH) and eclampsia, are closely associated with placental dysfunction. Genetic susceptibilities and poor placentation have been investigated intensively to understand the pathophysiology of PIH. It is currently thought that “poor placentation hypothesis”, in which extravillous trophoblasts fail to invade sufficiently the placental bed, explains in part maternal predisposition to this disease. Cumulative studies have suggested that hypoxic micromilieu of fetoplacental site, shear stress of uteroplacental blood flow, and aberrantly secreted proinflammatory substances into maternal circulation synergistically contribute to the progression of PIH. For example, soluble form of vascular endothelial growth factor receptor-1 (sVEGFR-1) and soluble form of CD105 are elevated in circulation of PIH mothers. However, it remains to be poorly understood the pathological events in the placenta during the last half of gestation as maternal systemic disorders get worse. For better understanding and effective therapeutic approaches to PIH, it is important to clarify pathological course of PIH-associated changes in the placenta. In this review, current understanding of placental development and the pathophysiology of PIH placenta are summarized. In addition, recent findings of vasoactive signalings in PIH and rodent PIH models are discussed.

Selective serotonin reuptake inhibitor use and risk of gestational hypertension

OBJECTIVE

The purpose of this study was to assess the effects of treatment with selective serotonin reuptake inhibitors (SSRIs) on the risks of gestational hypertension and preeclampsia.

METHOD

The authors analyzed data from 5,731 women with nonmalformed infants and no underlying hypertension who participated in the Slone Epidemiology Center Birth Defects Study from 1998 to 2007. Gestational hypertension was defined as incident hypertension diagnosed after 20 weeks of pregnancy, with and without proteinuria (i.e., with and without preeclampsia). The risks of gestational hypertension and preeclampsia were compared between women who did and did not receive SSRI treatment during pregnancy. Relative risks and 95% confidence intervals (CIs) were estimated using the Cox proportional hazards model, adjusting for prepregnancy sociodemographic, lifestyle, reproductive, and medical factors.

RESULTS

Gestational hypertension was present in 9.0% of the 5,532 women who were not treated with SSRIs and 19.1% of the 199 women who were treated with SSRIs. Among women who received treatment, gestational hypertension was present in 13.1% of the 107 women who received treatment only during the first trimester and in 26.1% of the 92 women who continued treatment beyond the first trimester. The occurrence of preeclampsia was 2.4% among women who were not treated with SSRIs, 3.7% among women who were exposed to SSRIs only during the first trimester, and 15.2% among women who continued SSRI treatment beyond the first trimester. Relative to women who did not receive treatment, the adjusted relative risk of preeclampsia was 1.4 for women who discontinued treatment and 4.9 for women who continued treatment.

CONCLUSION

SSRI exposure during late pregnancy-whether a causal factor or not-might identify women who are at an increased risk for gestational hypertension and preeclampsia. Further investigation is needed in order to separate the effects of treatment with SSRIs from those of underlying mood disorders.

Severe preeclampsia-related changes in gene expression at the maternal-fetal interface include sialic acid-binding immunoglobulin-like lectin-6 and pappalysin-2

Preeclampsia (PE), which affects 4-8% of human pregnancies, causes significant maternal and neonatal morbidity and mortality. Within the basal plate, placental cytotrophoblasts (CTBs) of fetal origin invade the uterus and extensively remodel the maternal vasculature. In PE, CTB invasion is often shallow, and vascular remodeling is rudimentary. To better understand possible causes, we conducted a global analysis of gene expression at the maternal-fetal interface in placental samples from women with PE (n = 12; 24-36 wk) vs. samples from women who delivered due to preterm labor with no evidence of infection (n = 11; 24-36 wk), a condition that our previous work showed is associated with normal CTB invasion. Using the HG-U133A&B Affymetrix GeneChip platform, and statistical significance set at log odds-ratio of B >0, 55 genes were differentially expressed in PE. They encoded proteins previously associated with PE [e.g. Flt-1 (vascular endothelial growth factor receptor-1), leptin, CRH, and inhibin] and novel molecules [e.g. sialic acid binding Ig-like lectin 6 (Siglec-6), a potential leptin receptor, and pappalysin-2 (PAPP-A2), a protease that cleaves IGF-binding proteins]. We used quantitative PCR to validate the expression patterns of a subset of the genes. At the protein level, we confirmed PE-related changes in the expression of Siglec-6 and PAPP-A2, which localized to invasive CTBs and syncytiotrophoblasts. Notably, Siglec-6 placental expression is uniquely human, as is spontaneous PE. The functional significance of these novel observations may provide new insights into the pathogenesis of PE, and assaying the circulating levels of these proteins could have clinical utility for predicting and/or diagnosing PE.

Pre-eclampsia: the pivotal role of the placenta in its pathophysiology and markers for early detection

Pre-eclampsia is the second leading cause of maternal morbidity and mortality in the United States. Infants born to affected mothers face a five-fold increase in death rate [Lain and Roberts 2002; National Heart Lung and Blood Institute 2001]. Although pre-eclampsia has been recognized by physicians for millennia, relatively little is known about its pathogenesis or prevention. Predicting its development is often extremely difficult, perhaps leading the Greeks to use the name 'eklampsis' meaning lightening. Recent studies provide novel insights into the role of the placenta in the development of pre-eclampsia and demonstrate novel markers to assist in predicting the onset of disease and potential therapeutic targets. Following an introduction which highlights the classification of hypertensive disorders of pregnancy and defines incidence and adverse outcomes of pre-eclampsia, this manuscript will discuss the role of the placenta in the pathophysiology of pre-eclampsia and recent markers that may predict its onset.

Markers of oxidative stress and systemic vasoconstriction in pregnant women drinking > or =48 g of alcohol per day

BACKGROUND

The precise pathway by which alcohol causes the characteristic features of fetal alcohol spectrum disorders is unknown. Proposed mechanisms for fetal injury from maternal alcohol use include cellular damage from oxidative stress and impaired fetal oxygenation related to maternal systemic vasoconstriction. Our objective was to compare the levels of urinary markers of oxidative stress and systemic vasoconstriction between women consuming large amounts of alcohol during pregnancy and women who did not drink alcohol during pregnancy.

METHODS

Pregnant women consuming > or =48 g alcohol per day (n = 29) on average and pregnant women who abstained from alcohol use (n = 39) were identified using detailed interviews and home visits. Random maternal urine specimens were collected. Urinary levels of the oxidative stress marker, 8-isoprostane F2alpha, and of the vasoactive prostaglandin metabolites, 2,3-dinor-6-keto-prostaglandin F1alpha (a vasodilator) and 11-dehydro-thromboxane B2 (a vasoconstrictor), were measured using mass spectrometric methods. All analyte levels were corrected for urinary creatinine.

RESULTS

In crude analyses, there was no significant difference in 8-isoprostane F2alpha between pregnant drinkers and nondrinkers (2.16 vs. 2.08 ng/mg creatinine, respectively, p = 0.87). There were no significant differences between the drinking and nondrinking groups in levels of 2,3-dinor-6-keto-prostaglandin F1alpha (1.03 vs. 1.17 ng/mg creatinine, respectively, p = 0.50), 11-dehydro-thromboxane B2 (0.72 vs. 0.59 ng/mg creatinine, respectively, p = 0.21), or the ratio of vasodilatory metabolite to vasoconstrictive metabolite (1.73 vs. 2.72, respectively, p = 0.14). Adjusting for maternal age, marital status, smoking, and gestational age at sampling did not substantially alter the results.

CONCLUSION

Our results show no difference in levels of urinary eicosanoid markers of oxidative stress and systemic vasoconstriction between pregnant women who drink heavily and pregnant women who abstain. These findings speak against a role for maternal oxidative stress or systemic vasoconstriction in the pathogenesis of alcohol damage to the fetus.

Pre-eclampsia: clinical manifestations and molecular mechanisms

Preeclampsia affects 3-5% of pregnancies and can have a significant impact on health for both mother and fetus. Risk factors include maternal co-morbidities such as obesity and chronic hypertension, paternal factors, and genetic factors. New hypertension and proteinuria during the second half of pregnancy are key diagnostic criteria, but the clinical features and associated prognostic implications are somewhat heterogeneous and may reflect different mechanisms of disease. Renal dysfunction and proteinuria correspond to the pathologic finding of glomerular endotheliosis, and generally resolve after cure of preeclampsia through fetal and placenta delivery. The molecular mechanisms behind this disease are being discovered and refined. The initial etiologic agents are currently unknown. Pathologic studies show abnormal development of an ischemic placenta with a high-resistance vasculature, which cannot deliver an adequate blood supply to the fetoplacental unit. Endothelial dysfunction plays a central role in the pathogenesis of the maternal syndrome. Dysfunctional endothelial cells produce altered quantities of vasoactive mediators, which lead to a tip in the balance towards vasoconstriction. An imbalance in circulating angiogenic factors is emerging as a prominent mechanism that mediates the endothelial dysfunction and the clinical signs and symptoms of preeclampsia. Soluble fms-like tyrosine kinase 1 (sFlt1), an endogenous anti-angiogenic factor that is a potent vascular endothelial growth factor (VEGF) antagonist, is highly elevated in preeclampsia. VEGF is not only important in angiogenesis, but also in maintaining endothelial health including the formation of endothelial fenestrae (a hallmark of the glomerular vascular endothelium). sFlt1 overexpression in animals induces glomerular endotheliosis with the loss of endothelial fenestrae that resembles the renal histological lesions of preeclampsia. More severe forms of preeclampsia, including the HELLP syndrome, may be explained by a concomitant elevation in both sFlt1 and soluble endoglin, another anti-angiogenic factor. Unraveling of the molecular mechanisms behind preeclampsia may help to expand our armamentarium to treat patients in a more directed fashion, as current management consists of supportive care and expedited delivery. Finally, long-term outcomes of women with preeclampsia include a significantly increased risk for hypertension and cardiovascular disease, including mortality, which may warrant more aggressive screening and treatment in this population.

Molecular mechanisms of preeclampsia

Preeclampsia is a major cause of maternal, fetal and neonatal mortality worldwide. The mechanisms that initiate preeclampsia in humans have been elusive, but some parts of the puzzle have begun to come together. A key discovery in the field was the realization that its major phenotypes, such as hypertension and proteinuria, are due to excess circulating soluble fms-like tyrosine kinase-1 (sFlt-1, also referred to as sVEGFR-1). sFlt-1 is an endogenous anti-angiogenic protein that is made by the placenta and acts by neutralizing the pro-angiogenic proteins vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). More recently, soluble endoglin, another circulating anti-angiogenic protein was found to synergize with sFlt-1 and contribute to the pathogenesis of preeclampsia. Abnormalities in these circulating angiogenic proteins are not only present during clinical preeclampsia, but also antedate clinical symptoms by several weeks. This review will summarize our current understanding of the molecular mechanism of preeclampsia, with an emphasis on the recently characterized circulating anti-angiogenic proteins.

Pathophysiology and medical management of systemic hypertension in preeclampsia

Hypertension that complicates preeclampsia in pregnancy is a disorder that requires special consideration in both prevention and pharmacologic treatment. In recent years, few advances have been made regarding the pathophysiology and prevention of preeclampsia; however, there have been some promising results from studies on possible modes of screening women for preeclampsia before clinical signs and symptoms are apparent. The recommendations for first-line drug therapy for the hypertensive complications of preeclampsia have changed little, primarily because first-line medications have had the advantage of extensive research experience. Recent clinical trials have demonstrated the efficacy and safety of various second-line drugs for the hypertensive complications of preeclampsia; whether these therapies can eventually replace the standard recommended first-line medications will require more extensive long-term investigation.

An animal model of intrauterine growth retardation induced by synthetic thromboxane a(2)

OBJECTIVE

Intrauterine growth retardation (IUGR) is an important cause of prenatal and neonatal morbidity, and neurologic abnormalities. Although several animal models of IUGR have been developed for scientific investigation, few models approximate the pathophysiology in human fetal growth failure resulting from pregnancy-induced hypertension and preeclampsia. We developed an animal model of IUGR in which fetal growth restriction was induced by administering a synthetic thromboxane A(2) analogue (STA(2)) to the mother.

METHODS

Timed pregnant Sprague-Dawley rats were used in this study. STA(2) was delivered into the peritoneal cavity of the pregnant female at a rate of 20 ng/h from day 13 of pregnancy. The effectiveness of this model was evaluated by monitoring the overall growth of the fetuses and neonates and measuring the weight and biochemical composition of individual organs.

RESULTS

Fetuses and neonates from the STA(2) group showed a highly significant weight reduction throughout the observation period from day 19 of gestation to postnatal day 7. Weight reduction near and at term exceeded 10% and became more pronounced during the first week after birth. Fetuses on the 20th gestational day exhibited a pattern of growth retardation characteristic of asymmetrical IUGR in which the weight reduction was prominent in the liver with relative sparing of the brain. However, the decrease in brain weight was more than 10%. The protein, DNA, and RNA contents of the liver were lower in the STA(2) group. The protein content of the forebrain and brainstem also decreased significantly in the STA(2) group compared with the control; however, the DNA content of the forebrain was higher in the STA(2) group.

CONCLUSIONS

This animal model may mimic human IUGR more closely than previous models because the growth restriction is induced in a truly chronic manner.

Soluble endoglin contributes to the pathogenesis of preeclampsia

Preeclampsia is a pregnancy-specific hypertensive syndrome that causes substantial maternal and fetal morbidity and mortality. Maternal endothelial dysfunction mediated by excess placenta-derived soluble VEGF receptor 1 (sVEGFR1 or sFlt1) is emerging as a prominent component in disease pathogenesis. We report a novel placenta-derived soluble TGF-beta coreceptor, endoglin (sEng), which is elevated in the sera of preeclamptic individuals, correlates with disease severity and falls after delivery. sEng inhibits formation of capillary tubes in vitro and induces vascular permeability and hypertension in vivo. Its effects in pregnant rats are amplified by coadministration of sFlt1, leading to severe preeclampsia including the HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome and restriction of fetal growth. sEng impairs binding of TGF-beta1 to its receptors and downstream signaling including effects on activation of eNOS and vasodilation, suggesting that sEng leads to dysregulated TGF-beta signaling in the vasculature. Our results suggest that sEng may act in concert with sFlt1 to induce severe preeclampsia.

Erythrocyte omega-3 and omega-6 polyunsaturated fatty acids and preeclampsia risk in Peruvian women

OBJECTIVE

This case-control study was conducted in Lima, Peru, from June 1997 through January 1998 to assess whether alteration in maternal erythrocyte omega-3 (n-3) and omega-6 (n-6) fatty acids was associated with increased risk of preeclampsia.

METHODS

A total of 99 preeclampsia and 100 normotensive pregnant women were included. Maternal erythrocyte n-3 and n-6 fatty acids were determined using capillary gas chromatography/mass spectrometry and expressed as micromolar (mM) concentrations. We employed logistic regression procedures to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULT

n-3 fatty acids were consistently lower in preeclampsia cases than controls. After adjusting for confounders, the corresponding ORs for preeclampsia across decreasing quartiles of sum of long-chain n-3 fatty acids were 1.0, 3.3, 2.4, and 3.3, respectively (P=0.07 for trend). A similar pattern was observed for eicosapentenoic acid (20:5n-3, EPA) and docosahexenoic acid (22:6n-3, DHA). There was no clear evidence of an association between arachidonic acid (20:4n-6, AA) and preeclampsia risk, the ORs in successively lower quartiles were 1.0, 1.1, 1.0, and 1.5 (P=0.48 for trend). A similar pattern was seen for the sum of long-chain n-6 fatty acids.

CONCLUSION

In Peruvian women, low erythrocyte n-3 fatty acids appeared to be associated with an increased risk of preeclampsia.

Pathophysiology and Medical Management of Systemic Hypertension in Pregnancy

Hypertension in pregnancy includes a group of distinct disorders that require special consideration in both prevention and pharmacologic treatment. In recent years, there have been few advances regarding the pathophysiology and prevention of preeclampsia or in the recommendations for first-line drug therapy for its hypertensive complications. Similarly, the recommendations for pharmacologic treatment of women with chronic hypertension antedating pregnancy have changed little primarily because first-line medications have the advantage of having had more extensive research experience. Recent clinical trials have demonstrated the efficacy and safety of various second-line drugs for the hypertensive disorders of pregnancy; whether these therapies can eventually replace the standard recommended medications will require more extensive long-term investigation.

Circulating Angiogenic Factors in the Pathogenesis and Prediction of Preeclampsia

Preeclampsia is a major cause of maternal, fetal, and neonatal mortality worldwide. Although the etiology of preeclampsia is still unclear, recent studies suggest that its major phenotypes, high blood pressure and proteinuria, are due in part to excess circulating soluble fms-like tyrosine kinase-1 concentrations. Soluble fms-like tyrosine kinase-1 is an endogenous antiangiogenic protein that is made by the placenta and acts by neutralizing the proangiogenic proteins vascular endothelial growth factor and placental growth factor. High serum soluble fms-like tyrosine kinase-1 and low serum free placental growth factor and free vascular endothelial growth factor have been observed in preeclampsia. Abnormalities in these circulating angiogenic proteins are not only present during clinical preeclampsia but also antedate clinical symptoms by several weeks. Therefore, this raises the possibility of measuring circulating angiogenic proteins in the blood and the urine as a diagnostic and screening tool for preeclampsia. The availability of a test to predict preeclampsia would be a powerful tool in preventing preeclampsia-induced mortality, especially in developing nations, where high-risk specialists are limited. This review will summarize our current understanding of the role of circulating angiogenic proteins in the pathogenesis and clinical diagnosis/prediction of preeclampsia.

Preeclampsia: a renal perspective

Preeclampsia is a syndrome that affects 5% of all pregnancies, producing substantial maternal and perinatal morbidity and mortality. The aim of this review is to summarize our current understanding of the pathogenesis of preeclampsia with special emphasis on the recent discovery that circulating anti-angiogenic proteins of placental origin may play an important role in the pathogenesis of proteinuria and hypertension of preeclampsia.

Soluble Fms-like tyrosine kinase 1 and endothelial dysfunction in the pathogenesis of preeclampsia

Preeclampsia, a pregnancy-specific syndrome of hypertension and proteinuria, is characterized by defective placental vasculogenesis and widespread maternal endothelial dysfunction. Although the manifestations of preeclampsia are primarily maternal, the burden of morbidity and mortality is often on the neonate, since the only effective treatment-delivery of the fetus and placenta-often results in iatrogenic prematurity. In this review, we summarize recent advances in our understanding of the pathophysiology of preeclampsia, including normal and aberrant placental vascular development and evidence for endothelial dysfunction. We describe recent evidence that supports a novel mechanism in which a maladaptive shift in placental production of angiogenic factors such as soluble fms-like tyrosine kinase 1 (a circulating antiangiogenic protein) may play an important role in the pathogenesis of preeclampsia.

Factors predisposing to pre-eclampsia in women with gestational diabetes

BACKGROUND

Lipid abnormalities occur before the onset of pre-eclampsia but their role in its pathogenesis is unclear. We tested the hypothesis that lipid abnormalities precede and contribute to the development of pre-eclampsia using women with gestational diabetes (GDM) as a focus population.

METHODS

One hundred and eighty-four women with a diagnosis of GDM were studied. Anthropometry, blood pressure, fasting lipids, glucose homeostasis, markers of inflammation and endothelial damage were measured and family history of disease was assessed to determine those measures at diagnosis of GDM that best predicted the development of pre-eclampsia.

RESULTS

Twelve percent of women with GDM developed pre-eclampsia. At diagnosis of GDM, total cholesterol, low-density lipoprotein and high-density lipoprotein cholesterol and triglycerides were not different in women who subsequently developed pre-eclampsia (GDM-PE). GDM-PE had elevated body mass index, blood pressure, fasting glucose, insulin, uric acid, and C-reactive protein (CRP), which have all been linked with the 'metabolic syndrome'. They had a greater degree of microalbuminuria and more frequently reported a family history of hypertension and maternal gestational diabetes. In logistic regression, the significant independent predictors for developing pre-eclampsia were fasting glucose, CRP, a family history of hypertension and the proband's mother having gestational diabetes.

CONCLUSION

The results suggest that, in GDM, increased severity of insulin resistance and related features of the 'metabolic syndrome', rather than lipid abnormalities, are precursors to the development of pre-eclampsia and hence are likely to be implicated in the pathophysiology of this disorder. Moreover, these women are likely to be at particularly high risk of long-term cardiovascular disease and Type 2 diabetes.

The role of regular physical activity in preeclampsia prevention

Preeclampsia affects 2-7% of pregnancies and is a leading cause of maternal and fetal morbidity and mortality. Despite extensive study, the etiology of preeclampsia is poorly understood. Abnormal placental development, predisposing maternal constitutional factors, oxidative stress, immune maladaptation, and genetic susceptibility have all been hypothesized to contribute to the development of preeclampsia. Physical conditioning and preeclampsia have opposite effects on critical physiological functions. This suggests that regular prenatal exercise may prevent or oppose the progression of the disease. Epidemiologic studies show that occupational and leisure-time physical activity is associated with a reduced incidence of preeclampsia. We hypothesize that this protective effect results from one of more of the following mechanisms: 1) stimulation of placental growth and vascularity, 2) reduction of oxidative stress, and 3) exercise-induced reversal of maternal endothelial dysfunction. Future research should include prospective epidemiological case-control studies that accurately measure occupational and leisure-time physical activity. Controlled randomized clinical trials examining the effects of prenatal exercise on biochemical markers for endothelial dysfunction, placental dysfunction, and oxidative stress are also needed. If future research supports the idea that exercise effectively protects against preeclampsia, this would provide a low-cost intervention that could dramatically improve prenatal care for women at risk of this disease.

Angiogenic Factors in the Pathogenesis of Preeclampsia

Preeclampsia affects 5-10% of pregnancies and is responsible for substantial maternal and neonatal morbidity and mortality. It is believed to be a two-stage disease with an initial placental trigger with no maternal symptoms followed by a maternal syndrome characterized by hypertension, proteinuria, and endothelial dysfunction. The first stage is thought to be due to shallow cytotrophoblast invasion of maternal spiral arterioles leading to placental insufficiency. The diseased placenta in turn releases soluble angiogenic factors that induce systemic endothelial dysfunction and clinical preeclampsia during the second stage. This review will discuss the role of circulating angiogenic factors of placental origin as potential mediators of the systemic endothelial dysfunction and the clinical syndrome of preeclampsia and provide an evolutionary explanation for this phenomenon.

Prostacyclin, thromboxane A and the effect of low-dose ASA in pregnancies at high risk for hypertensive disorders

BACKGROUND

The aim of this study was to investigate the prostanoid production in pregnancies at high risk for hypertensive disorders, and the effect of low-dose acetylsalicylic acid (ASA) on prostanoids.

MATERIAL AND METHODS

Ninety women with a bilateral notching in uterine arteries screened by Doppler ultrasound at 12-14 gestational weeks were randomized to the ASA (0.5 mg/kg/day) or placebo group. Forty-three women in both groups were followed up throughout the pregnancy. Urine samples were taken at baseline, and at 24-26 and 32-34 weeks of gestation to determine the urinary 11-dehydrothromboxane B(2) (u-11-dehydro-TxB(2)) and 2,3-dinor-6-keto-prostaglandin F(1alpha) (u-2,3-dinor-6-keto-PGF(1alpha)), the metabolites of thromboxane A(2) and prostacyclin, respectively.

RESULTS

In the pregnancies with pregnancy-induced hypertension (PIH) before 37 gestational weeks, the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydro-TxB(2) ratio did not increase as much as in other pregnancies (P = 0.028). In the placebo group pregnancies with preeclampsia had significantly lower 2,3-dinor-6-keto-PGF(1alpha) (P = 0.019) at 12-14 weeks of gestation compared to other pregnancies. In the placebo group the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydroTxB(2) ratio remained unchanged throughout the pregnancy, with no significant difference between pregnancies with a normal or an adverse outcome. In the ASA group the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydro-TxB(2) ratio increased (P < 0.001, early vs. midpregnancy). Again, the changes were similar in pregnancies with a normal or an adverse outcome.

CONCLUSION

The balance of prostacyclin and thromboxane A(2) shifted in an unfavorable direction in pregnancies complicated by PIH. ASA had a favorable effect on the prostanoids.

Placental protein 13 (PP-13): effects on cultured trophoblasts, and its detection in human body fluids in normal and pathological pregnancies

Placental tissue protein 13 (PP-13), one of the 56 known placental proteins identified till today, was purified from placentas obtained from women at delivery, and used to evoke antibodies against it. The purified PP-13 was lysed to peptides, which were sequenced, leading to the full-length cDNA sequencing and its expression in Escherichia coli. Sequence analysis in databases showed homology to the galectin family. Of the various antibody preparations developed, a pair of monoclonal antibodies (MAbs) coupled to the recombinant PP-13 (PP-13-R) was used for the immunodetection of PP-13 in pregnant women's serum with the solid-phase ELISA format. With a dynamic range of 25-500 pg/mL with no background in non-pregnant women's serum and men's serum, the ELISA test was suitable for the detection of PP-13 in the 1st, 2nd, and 3rd trimesters. PP-13 levels slowly increase during pregnancy. In the 1st trimester, lower than normal PP-13 levels were found in fetal growth restriction (IUGR), preeclampsia (PE), and particularly in early PE (<34 weeks of gestation). In the 2nd and 3rd trimesters, higher than normal concentrations were found in PE, IUGR and in preterm delivery (PTD). Application of PP-13 to cultured trophoblasts elicited depolarization carried by calcium ions, followed by liberation of linoleic and arachidonic acids from the trophoblast membrane, and a subsequent elevation of prostacyclin and thromboxane. These effects were negligible when PP-13 derived from the placentas of patients with IUGR, PE or PTD was used. The results are discussed in view of the potential utilization of PP-13 for early serum screening to assess the risk to develop placental insufficiency, coupled to a differential analysis of the various pathologies by analyzing cultured trophoblasts.

Women and Omega-3 Fatty Acids

Omega-3 fatty acids (omega-3 FA) are constituents of the membranes of all cells in the body and are precursors of locally produced hormones, eicosanoids, which are important in the prevention and treatment of various diseases, especially in women. Omega-3 FA are of interest in some of the most common conditions affecting women. One mechanism underlying dysmenorrhea is a disturbed balance between antiinflammatory, vasodilator eicosanoids derived from omega-3 FA and proinflammatory, vasoconstrictor eicosanoids derived from omega-6 FA. Increased intake of omega-3 FA can reverse the symptoms in this condition by decreasing the amount of omega-6 FA in cell membranes. An increased prostacyclin/thromboxane ratio induced by omega-3 FA can facilitate pregnancy in women with infertility problems by increasing uterine blood flow. Supplementation with omega-3 FA during pregnancy lowers the risk of premature birth and can increase the length of pregnancy and birth weight by altering the balance of eicosanoids involved in labor and promote fetal growth by improving placental blood flow. Intake of omega-3 FA during pregnancy and breast feeding may facilitate the child's brain development. There is also some evidence that supplementation with omega-3 FA might help to prevent preeclampsia, postpartum depression, menopausal problems, postmenopausal osteoporosis, and breast cancer. Furthermore, because elevated triglyceride levels are associated with cardiovascular disease, especially in women; and because omega-3 FA have powerful effects on triglycerides, women in particular gain from an increased intake of these fatty acids. This is especially important in women receiving hormone therapy, which can increase triglyceride levels. The quality of the omega-3 FA preparation is important. It should have an appropriate antioxidant content not to induce lipid peroxidation, and its content of dioxin and polychlorinated biphenyls (PCBs) should be well below the established safe limit.

Prostaglandin synthases: recent developments and a novel hypothesis

Cells are continuously exposed to cues, which signal cell survival or death. Fine-tuning of these conflicting signals is essential for tissue development and homeostasis, and defective pathways are linked to many disease processes, especially cancer. It is well established that prostaglandins (PGs), as signalling molecules, are important regulators of cell proliferation, differentiation and apoptosis. PG production has been a focus of many researchers interested in the mechanisms of parturition. Previously, investigators have focussed on the committed step of PG biosynthesis, the conversion by prostaglandin H synthase (PGHS; also termed cyclo-oxygenase, COX) of arachidonic acid (AA) (substrate) to PGH2, the common precursor for biosynthesis of the various prostanoids. However, recently the genes encoding the terminal synthase enzymes involved in converting PGH2 to each of the bioactive PGs, including the major uterotonic PGs, PGE2 (PGE synthase) and PGF2alpha (PGF synthase), have been cloned and characterized. This review highlights how the regulation of the expression and balance of key enzymes can produce, from a single precursor, prostanoids with varied and often opposing effects.

Eicosanoids in preeclampsia

Preeclampsia is characterized by an imbalance between two cyclooxygenase metabolites of arachidonic acid, thromboxane and prostacyclin, that favors thromboxane. Because of the biologic actions of these two eicosanoids, this imbalance might explain major clinical symptoms of preeclampsia, such as hypertension, platelet aggregation and reduced uteroplacental blood flow. In the maternal circulation, this imbalance is primarily manifested by decreased production of prostacyclin by endothelial cells. Platelet thromboxane synthesis is only increased in severe preeclampsia. In the placenta and in leukocytes, the imbalance is exacerbated by increased production of thromboxane coupled with decreased production of prostacyclin in both mild and severe preeclampsia. Longitudinal measurements of urinary metabolites of thromboxane and prostacyclin reveal that the thromboxane/prostacyclin imbalance predates the onset of clinical symptoms of preeclampsia. The imbalance between thromboxane and prostacyclin is most likely caused by oxidative stress, which is manifest in preeclampsia by increased lipid peroxidation and decreased antioxidant protection. Oxidative stress may drive this imbalance because lipid peroxides activate the cyclooxygenase enzyme to increase thromboxane synthesis, but at the same time they inhibit prostacyclin synthase to decrease prostacyclin synthesis. Low-dose aspirin therapy (50-150 mg/day) has been considered for the prevention of preeclampsia because it selectively inhibits thromboxane synthesis. Several studies reported dramatic decreases in the incidence of preeclampsia with low-dose aspirin therapy. However, two large multicenter studies reported only modest decreases, which dampened enthusiasm. The two large studies were "intent to treat" studies which included patients who were noncompliant and who discontinued the use of aspirin. In one of the studies for which compliance statistics were available only 53% of the aspirin group had a compliance rate greater than 75%, which raises a question as to whether the effectiveness of aspirin was being tested. Low-dose aspirin therapy should not yet be dismissed for the prevention of preeclampsia, but be reconsidered with emphasis on compliance using doses of aspirin in the range of 100-150 mg/day combined with antioxidants.

Cardiovascular and thromboembolic events following hypertensive pregnancy

BACKGROUND

Hypertension is a common complication of pregnancy. Previous evidence has linked pregnancy-related hypertension to maternal cardiovascular disease. We conducted a population-based cohort study to estimate the risks for cardiovascular and thromboembolic events in women with pregnancy-related hypertension.

METHODS

We analyzed data from all singleton births recorded in Washington State from 1987 to 1998. Mothers were classified as having gestational hypertension, preeclampsia, or chronic hypertension based on hospital discharge and birth record information. Birth records were linked to subsequent hospitalizations within Washington State. Proportional hazards models were used to estimate the relationship between each form of pregnancy-related hypertension and subsequent risk for cardiovascular and thromboembolic events.

RESULTS

We identified 31,239 eligible hypertensive pregnancies from 807,010 births. During follow-up, there were 118 hospitalizations for a first acute cardiovascular event and 172 hospitalizations for a first thromboembolic event. Gestational hypertension, mild preeclampsia, and severe preeclampsia were associated with 2.8-fold (95% confidence interval [CI], 1.6 to 4.8), 2.2-fold (95% CI, 1.3 to 3.6), and 3.3-fold (95% CI, 1.7 to 6.5) greater risks for cardiovascular events, respectively. Severe preeclampsia was associated with a 2.3-fold (95% CI, 1.3 to 4.2) greater risk for thromboembolic events.

CONCLUSION

Preeclampsia and gestational hypertension are associated with increased risk for cardiovascular events. Pregnancy-induced hypertension appears to be an important risk factor for the development of future cardiovascular disease in young women.

Haemostatic changes in pregnancy

Normal pregnancy is accompanied by changes in the coagulation and fibrinolytic systems. These include increases in a number of clotting factors (I, II, VII, VIII, IX and XII), a decrease in protein S levels and inhibition of fibrinolysis. As gestation progresses, there is also a significant fall in the activity of activated protein C, an important anticoagulant. While these physiological changes may be important for minimizing intrapartum blood loss, they entail an increased risk of thromboembolism during pregnancy and the post-partum period.

Prenatal screening, epidemiology, diagnosis, and management of preeclampsia

The cause of preeclampsia remains unknown. The disease manifests itself across a broad clinical spectrum from mild to severe, conferring vastly different morbidities and suggesting possibly different disease processes. Oxidative stress, endothelial dysfunction, maternal-fetal immune incompatibility, and abnormal placental implantation are among the suggested causes. The need for a marker or set of markers that allow for definitive diagnosis and assessment of future risk of preeclampsia is tremendous. Ultrasound techniques and several markers have been identified that are increased among patients with preeclampsia, but no test is highly sensitive. In the future, a combination of markers likely will be used to assess risk and, establish the diagnosis, and test treatment strategies. Such an approach would allow for more refined treatment studies of patients who are at highest risk for preeclampsia.

Aspirin (100 mg) used for prevention of pre-eclampsia in nulliparous women: the Essai Régional Aspirine Mère-Enfant study (Part 1)

OBJECTIVE

To reduce the incidence of pre-eclampsia in nulliparous women, in accordance with the suggestion of a recent meta-analysis that low dose aspirin might decrease this incidence by more than half if used early enough in and at a sufficient dose during pregnancy (more than 75 mg).

DESIGN

Multicentre randomised double-blinded placebo-controlled trial.

SETTING

Twenty eight centres in Northern of France and one in Belgium.

POPULATION

Three thousand and two hundred ninety-four nulliparous women recruited between 14 and 20 weeks.

METHODS

Randomisation to either 100 mg aspirin or placebo daily from inclusion through 34 weeks.

MAIN OUTCOME MEASURES

Preeclampsia was defined as hypertension (> or =140 and or 90 mmHg) associated with proteinuria (> or =0.5 g/L).

RESULTS

The aspirin (n = 1644) and placebo (n = 1650) groups did not differ significantly in the mothers' incidence of pre-eclampsia (28 of 1632 [1.7%] vs 26 of 1637 [1.6%]; relative risk, RR, 1.08, 95% CI 0.64-1.83), hypertension, HELLP syndrome or placental abruption, or in the children's incidence of perinatal deaths or birthweight below the 10th centile. The incidence of babies with birthweight below the third centile was significantly higher in the aspirin group, with no explanation. The incidence of maternal side effects was higher in the aspirin group, principally because of a significantly higher rate of haemorrhage.

CONCLUSIONS

Aspirin at a dose of 100 mg does not reduce the incidence of pre-eclampsia in nulliparous women. Aspirin (100 mg) is associated with an increase in bleeding complications.

Randomised comparison of uterine artery Doppler and aspirin (100 mg) with placebo in nulliparous women: the Essai Régional Aspirine Mère-Enfant study (Part 2)

OBJECTIVE

To assess the effectiveness of a pre-eclampsia prevention strategy based on routine uterine artery Doppler flow velocity waveform examination during the second trimester of pregnancy, followed by a prescription for 100 mg aspirin in the case of abnormal Doppler findings.

DESIGN

Multicentre randomised controlled trial.

SETTING

Eleven centres in the north of France and one in Belgium.

POPULATION

One thousand and eight hundred and fifty-three nulliparous women recruited between 14 and 20 weeks of gestation.

METHODS

Randomisation either to undergo a uterine Doppler examination between 22 and 24 week of gestation or to take a placebo. Women with abnormal Doppler waveforms received 100 mg of aspirin daily from Doppler examination through 36 weeks.

MAIN OUTCOME MEASURES

Pre-eclampsia was defined as hypertension (> or = 140 and/or 90 mmHg) associated with proteinuria (> or = 0.5 g/L).

RESULTS

One thousand two hundred and fifty-three women (67%) were randomised into the systematic Doppler group and 617 (33%) into the placebo group. Of the 1175 patients in the Doppler group who underwent this examination, 239 (20.3%) had abnormal uterine artery Doppler and received a prescription for aspirin. Despite the aspirin prescription, the frequency of pre-eclampsia did not differ between the systematic Doppler group and the placebo group (28 of 1237 [2.3%] vs 9 of 616 [1.5%]; RR = 1.55, 95% CI 0.7-3.3). Furthermore, the groups did not differ in the frequency of children who were very small for their gestational age (< or =3rd centile) or for perinatal deaths. Compared with patients with normal Doppler findings, those with abnormal Doppler were at high risk of pre-eclampsia (RR = 5.5, 95% CI 2.5-12.2) and of giving birth to a small-for-gestational-age child (RR = 3.6, 95% CI 1.6-8.1).

CONCLUSION

Despite its sensitivity in screening for pre-eclampsia, routine uterine Doppler in the second trimester cannot be recommended for nulliparous patients.

Prostacyclin/thromboxane early changes in pregnancies that are complicated by preeclampsia

OBJECTIVE

The purpose of this study was to examine 6-keto-prostaglandin F(1)(alpha) and thromboxane B(2) plasma levels throughout normotensive and preeclamptic pregnancies and to analyze the predictive values of these quantifications for the detection of preeclampsia during the second trimester of pregnancy.

STUDY DESIGN

Blood samples were collected from 30 healthy, nonpregnant women and at 4-week intervals from a cohort of nulliparous women who were recruited before 16 weeks of gestation. Preeclampsia developed in 26 patients; 52 normotensive control subjects were matched from the same cohort. The 6-keto-prostaglandin F(1)(alpha) and thromboxane B(2) were assayed by radioimmunoassay. Trends were compared between pregnancy groups and with the nonpregnant women. Predictive values were determined with the second-trimester assessments.

RESULTS

The 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio decreased throughout pregnancy in women with preeclampsia; there were no significant changes in normotensive women. We found higher thromboxane B(2) levels within the group with preeclampsia during the first gestational trimester (preeclampsia, 188 +/- 17 pg/mL; control, 119 +/- 4.8 pg/mL [mean +/- SEM]; P =.001). During the third trimester, patients with preeclampsia had lower 6-keto-prostaglandin F(1)(alpha) levels than did control subjects (preeclampsia, 191 +/- 9.8 pg/mL; control, 288 +/- 10 pg/mL; P =.001). The 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio was suitable to calculate predictive values; the best cutoff point and time interval were 3.0 and 22 to 26 weeks of gestation, respectively. Sensitivity, specificity, and positive and negative predictive values were 88%, 97%, 69%, and 99%, respectively; the odds ratio was 14.6 (95% CI, 6.9-30.4).

CONCLUSION

The prostacyclin/thromboxane ratio favored vasoconstriction early in gestation in women in whom preeclampsia developed. A 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio of <or=3.0 at 22 to 26 weeks of gestation had a high predictive value for the development of preeclampsia.

Neutrophil activation and production of reactive oxygen species in pre-eclampsia

OBJECTIVE

To investigate neutrophil NADPH oxidase activation and subsequent production of reactive oxygen species (ROS) in pre-eclampsia.

DESIGN

Baseline values and the activated response of neutrophils upon stimulation of the NADPH oxidase with the agonists was measured. Neutrophils from 17 third-trimester pre-eclamptic and 17 age- and gestation-matched normal pregnant women were examined.

METHODS

Neutrophil ROS production was measured by both lucigenin- and luminol-derived chemiluminescence. The abundance of the various phox proteins was examined using Western blotting techniques. Lucigenin-derived ROS generation was significantly increased in neutrophils isolated from women with pre-eclampsia compared with normotensive controls in the case of both agonists [n-formyl-met-leu-phe (fMLP): pre-eclamptic 2.071 +/- 0.336 relative light units seconds (RLU.s) and normotensive 1.141 +/- 0.249 RLU.s, P = 0.035; phorbol-12-myristate-13-acetate (PMA): pre-eclamptic 34.954 +/- 2.634 RLU.s and normotensive 17.208 +/- 3.325 RLU.s, P = 0.0001]. Luminol-derived ROS generation was also significantly increased in the neutrophils isolated from the women with pre-eclampsia compared with the normotensive controls in the case of both agonists (fMLP: pre-eclamptic 1.955 +/- 0.316 RLU.s and normotensive 1.058 +/- 0.191 RLU.s, P = 0.023; PMA: pre-eclamptic 4.108 +/- 0.351 RLU.s and normotensive 3.073 +/- 0.332 RLU.s, P = 0.042). There were no differences between the relative abundance of the phox proteins in the two groups.

CONCLUSIONS

Neutrophils isolated from women with pre-eclampsia during the third trimester showed increased sensitivity to agonist stimulation and produced significantly more ROS than age-matched normotensive controls. This was not due to an increased abundance of any of the phox proteins. Increased ROS production in pre-eclampsia may highlight a role for neutrophils in the oxidative stress and associated endothelial dysfunction that are characteristic of the condition.

Hypertensive emergencies: diagnosis and management

The treatment of hypertension is preventive medicine. This principle applies in the emergency room as well as the clinic. However, there are crucial contrasts between these two care settings related to specific goals of management for real emergencies and nonemergency conditions. In the emergency room, rapid triage is necessary to separate those who can safely be sent home for future clinic assessment from those who require immediate interventions including short stays in 24-hour observation units or hospitalization for more serious problems. This review focuses on decisions related to hypertension management in the emergency room and over brief periods of observation and treatment. Strategy is supported by evidence-based considerations whenever possible. Where outcome studies are not available, we rely on the rationale derived from relevant clinical research.

Recent Insights into the pathogenesis of pre-eclampsia

Pre-eclampsia is more than pregnancy induced hypertension. The emerging view described in this presentation is that pre-eclampsia is secondary to the interactions of reduced placental perfusion with diverse maternal factors that alter endothelial function. The maternal contribution is from factors that antedate pregnancy and are influenced by the usual metabolic adaptations of pregnancy. The endothelium and other targets for the effects of these interactions are more sensitive to insults during pregnancy because of activation of the inflammatory cascade as a normal part of pregnancy. At least part of the response to reduced placental perfusion may be a fetal adaptive response to attempt to overcome the reduced delivery of nutrients. A reasonable convergence point for the interaction is at the level of oxidative stress. This hypothesis has both encouraging and discouraging corollaries. The diversity of maternal factors argues that there will be no single gene to explain the disorder and no single 'magic bullet' to treat the disorder. However, it is encouraging that the recognition of maternal predisposition to the disorder directs therapy to prevent pre-eclampsia at a specific target in subsets of women. Finally, the suggestion that some of the maternal alterations are due to fetal adaptive responses encourages careful choices of agents and meticulous infant follow up in well planned clinical trials.

The effect of Enalapril on PGI(2) and NO levels in hypertensive patients

The effects of the angiotensin-converting enzyme inhibitors (ACEIs), may be partially mediated by the kinins' paracrine influence. Their actions may be exerted through nitric oxide and prostacyclin (PGI(2)) synthesis stimulation. The aim of our study was to determine whether the antihypertensive effect of Enalapril correlated with the increment in the plasmatic levels of NO and PGI(2) in essential moderate hypertensive patients. Normalization of blood pressure was observed in 20 patients, four on the 28th day, 15 on the 42th day and one on the 56th day. Enalapril-respondent subjects showed increased nitrate/nitrite levels on the 14th day (30% increment), on the 28th day (64%), on the 42th day (93.5%) and on the 56th day (96.2%) compared with basal levels, but they did not modify the circulating 6-keto PGF(1 alpha) levels. Four non-respondent patients showed a diminution in nitrate/nitrite and 6-keto PGF(1 alpha) circulating levels along the treatment. We conclude that the administration of 5-30 mg of Enalapril increases circulating NO metabolites in respondent-essential hypertensive subjects. The lack of responsiveness to the treatment may be related to the presence of risk factors such as those linked to an increase of oxidative stress. Finally, we consider that the evaluation of circulating NO may represent a predictive of the response to Enalapril in essential hypertensive patients.

Placental regulation of fatty acid delivery and its effect on fetal growth--a review

More than 90 per cent of the fat deposition in the fetus occurs in the last 10 weeks of pregnancy during which it increases exponentially to reach a rate of accretion of around 7 g/day close to term. All of the n -3 and n -6 fatty acid structure acquired by the fetus has to cross the placenta and fetal blood is enriched in long chain polyunsaturated fatty acids (LCPUFA) relative to the maternal supply. The placenta may regulate its own fatty acid substrate supply via the action of placental leptin on maternal adipose tissue. Fatty acids cross the microvillous and basal membranes by simple diffusion and via the action of membrane bound and cytosolic fatty acid binding proteins (FABPs). The direction and magnitude of fatty acid flux is mainly dictated by the relative abundance of available binding sites. The fatty acid mix delivered to the fetus is largely determined by the fatty acid composition of the maternal blood although the placenta is able to preferentially transfer the important PUFA to the fetus as a result of selective uptake by the syncytiotrophoblast, intracellular metabolic channelling of individual fatty acids, and selective export to the fetal circulation. Placental FABP polymorphisms may affect these processes. There is little evidence to suggest that placental delivery of fatty acids limits normal fetal growth although the importance of the in utero supply may be to support post-natal development as most of the LCPUFA accumulated by the fetus is stored in the adipose tissue for use in early post-natal life.

17beta-estradiol increases rat cerebrovascular prostacyclin synthesis by elevating cyclooxygenase-1 and prostacyclin synthase

BACKGROUND AND PURPOSE

It has been reported that estrogens modulate peripheral vascular synthesis of vasodilatory hormones, including prostacyclin. If this occurs in the cerebral circulation, it could have important consequences in the modulation of cerebral hemodynamic function and improvement of stroke outcome. We investigated the hypothesis that in vivo 17beta-estradiol treatment of ovariectomized rats increases cerebrovascular prostacyclin production via elevation of the enzymes responsible for prostacyclin synthesis.

METHODS

Cerebral blood vessels from 17beta-estradiol-treated and nontreated ovariectomized rats were isolated and examined for prostacyclin synthesis by enzyme-linked immunosorbent assay or for protein levels of cyclooxygenase-1, prostacyclin-synthase, and cytosolic phospholipase A2 by immunoblot analysis.

RESULTS

We report that chronic in vivo 17beta-estradiol treatment significantly enhanced basal prostacyclin synthesis in rat cerebral blood vessels by 2.6-fold over control. 17beta-estradiol treatment also resulted in a 5.1-fold increase of cyclooxygenase-1 protein and a 6.7-fold increase of prostacyclin-synthase protein in the cerebral vasculature. There was no effect of estrogen on levels of cytosolic phospholipase A2.

CONCLUSIONS

Our findings suggest that estrogen influences the biosynthesis of prostacyclin, which may be important in the regulation of cerebral blood flow and thrombosis. This finding may shed light on the mechanisms that govern sex-based differences in cerebrovascular disease.

Possible beneficial effect of exercise, by reducing oxidative stress, on the incidence of preeclampsia

We hypothesize that regular exercise enhances antioxidative enzymes in pregnant women, which reduce oxidative stress and, thus, the incidence of preeclampsia. Oxidative stress with enhanced lipid peroxide formation could lead to endothelial dysfunction in preeclampsia. Other conditions, such as increased transferrin saturation and decreased iron-binding capacity, directly and indirectly promote the process of oxidative stress and subsequent endothelial dysfunction. Exercise increases oxidative metabolism and produces a prooxidant environment. This acidic environment during exercise (at or beyond anaerobic threshold) promotes oxygen release from hemoglobin and increases in PO(2) in tissues, as well as releases iron from transferrin. When exercise is repeated regularly, the body promptly adjusts so that oxidative stress is eliminated or reduced. The body's adaptations to a regular exercise habit seem to have an antioxidant effect. In humans, training effects have been identified with an enhanced activity of antioxidative enzymes. Another concerted adaptation that regular exercise brings to women's bodies is resistance against production of prooxidants by increasing the number of mitochondria. Equally important is a training effect that decreases susceptibility to lipid peroxidation. Evidence suggests that physically active women are less likely to develop preeclampsia. In theory, intracellular and extracellular conditions resulting from regular exercise should counteract the enhancement of oxidative stress, thus interfering with the process leading to endothelial dysfunction. This position paper describes a hypothesis and includes a brief review of exercise physiology and biochemical research in preeclampsia. Unlike other preventive treatments, such as aspirin or calcium supplements, a regular exercise habit leads to a positive and healthy lifestyle without concern of side effects.

Urinary vasodilator and vasoconstrictor angiotensins during menstrual cycle, pregnancy, and lactation

Since normal human pregnancy is characterized by normotension in the face of an increased renin-angiotensin-aldosterone system (RAAS), we evaluated the temporal pattern of urinary excretion of a novel vasodilator within this system, angiotensin-(1-7) (Ang-[1-7]), during the menstrual cycle, pregnancy, and lactation. The urinary profiles of Ang I, Ang II, human chorionic gonadotropin, 17beta-estradiol, and progesterone were also determined. During the menstrual cycle, urinary Ang-(1-7) and Ang II remained stable (mean cycle value: 94.6 +/- 11.3 and 11.4 +/- 1.1 pmol/g of creatinine, respectively) in nine females. In 10 normal pregnant women, urinary Ang-(1-7) and Ang II increased throughout gestation, averaging 1499.8 +/- 310 and 224.4 +/- 58 pmol/g of creatinine, respectively (p < 0.05) at wk 35 and falling during lactation to 394.0 +/- 95 and 65.7 +/- 20 pmol/ g of creatinine (p < 0.05), respectively. The Ang-(1-7)/Ang II ratio was unchanged in the different reproductive periods. During the menstrual cycle, Ang II and Ang-(1-7) correlated with 17beta-estradiol and progesterone using multivariate analysis (r = 0.31, p < 0.001) and r = 0.28, p < 0.02, respectively). During gestation, 17beta-estradiol and progesterone correlated with urinary Ang-(1-7) (r = 0.48, p < 0.001 and r = 0.47, p < 0.001, respectively) and Ang II (r = 0.24, p < 0.03 and r = 0.25, p < 0.03, respectively); by multiple regression, only Ang-(1-7) correlated with both steroids (r = 0.49,p < 0.001). The progressive rise of Ang-(1-7) throughout gestation, probably modulated by estrogen and progesterone, suggests a physiologic counterregulation within the RAAS.

Thromboxane A(2) limits differentiation and enhances apoptosis of cultured human trophoblasts

Prostanoids influence differentiation in diverse cell types. Altered expression of cyclooxygenase and prostaglandins has been implicated in the pathophysiology of placental dysfunction, which results in preeclampsia and fetal growth restriction. We hypothesized that prostanoids modulate differentiation and apoptosis in cultured human trophoblasts. Villous cytotrophoblasts were isolated from term human placentas and cultured in serum-free medium. The level of human chorionic gonadotropin was used as a marker of biochemical differentiation of primary trophoblasts, and syncytia formation was used as a marker of morphologic differentiation. Of the prostanoids tested, we found exposure to thromboxane A(2) hindered both biochemical and morphologic differentiation of cultured trophoblasts. As expected, human chorionic gonadotropin levels in the media were elevated in a concentration-dependent manner in the presence of the thromboxane synthase inhibitor, sodium furegrelate, or the thromboxane A(2) receptor blocker SQ 29,548. Furthermore, thromboxane A(2) enhanced trophoblast apoptosis, determined using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, cell morphology, and a concentration-dependent increase in p53 expression. We conclude that thromboxane A(2) hinders differentiation and enhances apoptosis in cultured trophoblasts from term human placenta. We speculate that thromboxane may contribute to placental dysfunction by restricting differentiation and enhancing apoptosis in human trophoblasts.

Urinary prostaglandin excretion in pregnancy: the effect of dietary sodium restriction

INTRODUCTION

Dietary sodium restriction results in activation of the renin-angiotensin-aldosterone-system. In the non-pregnant situation renin release in response to a low sodium diet is mediated by prostaglandins. We studied the effect of dietary sodium restriction on urinary prostaglandin metabolism in pregnancy.

PATIENTS AND METHODS

In a randomized, longitudinal study the excretion of urinary metabolites of prostacyclin (6-keto-PGF(1 alpha)and 2,3-dinor-6-keto-PGF(1 alpha)) and thromboxane A(2)(TxB(2)and 2,3-dinor-TxB(2)) was determined throughout pregnancy and post partum in 12 women on a low sodium diet and in 12 controls.

RESULTS

In pregnancy the excretion of all urinary prostaglandins is increased. The 6-keto-PGF(1 alpha)/ TxB(2)-ratio as well as the 2, 3-dinor-6-keto-PGF(1 alpha)/ 2,3-dinor-TxB(2)-ratio did not significantly change in pregnancy. CONCLUISION Prostacyclin and thromboxane do not seem to play an important role in sodium balance during pregnancy.