Urinary Metabolites Of Prostacyclin Research Articles

Poor Responsiveness to Low-Dose Aspirin Contributes to Persistent In Vivo Platelet Activation in Polycythemia Vera

▪Introduction . Polycythemia Vera (PV) is a myeloproliferative neoplasm characterized by peripheral erythrocytosis, increased thrombotic risk affecting morbidity and mortality. Low-dose aspirin once-daily (od) is currently recommended for cardiovascular prevention in PV. However, it has been recently suggested that aspirin should be used at 100 mg twice-daily (bid) in PV patients at high cardiovascular risk (JAK2V617F allelic burden, age >60 years) on the assumption of a shorter lasting antiplatelet effect, similarly to essential thrombocythemia. However, pharmacological and clinical data supporting the need for a bid ASA regimen in PV are missing.Methods . We studied the platelet responsiveness to standard aspirin (100 mg od) in PV patients, assessed at the end of the 24-h dosing interval. Patients were diagnosed according to the WHO 2008 criteria, were all on od low-dose aspirin and underwent a run-in phase (7-10 days) where aspirin tablets were always ingested at breakfast. Routine hematochemistry, genotype and allelic burden, clinical characteristics and history, medications were recorded. Serum thromboxane B2 (sTXB2) was measured as ex vivo biomarker of aspirin pharmacodynamics, urinary 11-deidro-TXB2 (TXM) as in vivo index of platelet activation, the major urinary prostacyclin metabolite, 2,3 dinor 6-keto-PGF1α (PGIM), the urinary isoprostane 8-iso-PGF2α and plasma salicylic acid esterase activity.Results . Forty-nine patients (67±10 years, 16 females) on aspirin for ≥1 month gave their informed consent; aspirin compliance and non-steroidal anti-inflammatory drug intake were checked by phone calls and patient's interview on the day of the visit. Nine patients were on phlebotomy only, while the remaining patients were on phlebotomy and hydroxyurea to keep the hematocrit <45%. Average hematologic values were: hematocrit 43.8±3%; erythrocytes 5.3±1.3x106/µL; leukocytes 9.1±4.3x103/µL, platelets 359±165x103/µL, immature platelets 11.8±7.4x103/µL. The median sTXB2 value was 8.6 [2-50] ng/ml, urinary TXM 509 [205-3428] pg/mg creatinine, 8-iso-PGF2α 768 [234-2104] pg/mg creatinine, PGIM 172 [120-275] pg/mg creatinine, plasma esterase activity 53 [47-60] µmol/L salycilic acid/min. Overall, sTXB2 significantly (p<0.01) correlated with immature platelets (rho=0.46), erythrocyte count (rho=0.41), leukocytes (rho=0.39). Patients were then divided according to sTXB2 tertiles, and patients in the lowest tertile showed sTXB2 levels within the expected range (3.4 [2.4-4.2] ng/ml, Figure). The patients in the upper tertile of sTXB2 levels (19.8 [15.3-40.9] ng/ml) were characterized by significantly (p<0.05) higher erythrocyte counts, total platelet counts, and immature platelets (p=0.05), while age, JAK2V617F allelic burden, leukocytes, hematocrit, hemoglobin, and sex distribution were comparable across tertiles. Urinary TXM significantly (p<0.05) correlated with sTXB2 (rho=0.39 and Figure), disease duration (rho=0.33), and leukocytes (rho=0.33). By multivariable analysis, only sTXB2 (p=0.009) positively predicted urinary TXM excretion. Urinary PGIM correlated with 8-iso-PGF2α excretion but not with TXM. Plasma esterase activity correlated with hemoglobin levels (rho=0.33, p=0.04), but not with the hematocrit, erythrocyte count, urinary TXM or sTXB2. JAK2V617F burden was significantly associated with polymorphonucleate count (rho=0.65), hemoglobin (rho=-0.49), and male sex (rho=0.41) while it was unrelated to previous thrombosis, sTXB2, urinary TXM and PGIM. By multivariable analysis JAK2V617F allelic burden predicted leukocyte counts only.Conclusions . A fraction of PV patients characterized by high erythrocyte, platelet and immature platelet count have a reduced response to a standard regimen of low-dose aspirin, which may contribute to persistently enhanced in vivo platelet activation. An improved antiplatelet regimen should be tested in these patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A randomized double-blind trial of 3 aspirin regimens to optimize antiplatelet therapy in essential thrombocythemia

AbstractEssential thrombocythemia (ET) is characterized by abnormal megakaryopoiesis and enhanced thrombotic risk. Once-daily low-dose aspirin is the recommended antithrombotic regimen, but accelerated platelet generation may reduce the duration of platelet cyclooxygenase-1 (COX-1) inhibition. We performed a multicenter double-blind trial to investigate the efficacy of 3 aspirin regimens in optimizing platelet COX-1 inhibition while preserving COX-2–dependent vascular thromboresistance. Patients on chronic once-daily low-dose aspirin (n = 245) were randomized (1:1:1) to receive 100 mg of aspirin 1, 2, or 3 times daily for 2 weeks. Serum thromboxane B2 (sTXB2), a validated biomarker of platelet COX-1 activity, and urinary prostacyclin metabolite (PGIM) excretion were measured at randomization and after 2 weeks, as primary surrogate end points of efficacy and safety, respectively. Urinary TX metabolite (TXM) excretion, gastrointestinal tolerance, and ET-related symptoms were also investigated. Evaluable patients assigned to the twice-daily and thrice-daily regimens showed substantially reduced interindividual variability and lower median (interquartile range) values for sTXB2 (ng/mL) compared with the once-daily arm: 4 (2.1-6.7; n = 79), 2.5 (1.4-5.65, n = 79), and 19.3 (9.7-40; n = 85), respectively. Urinary PGIM was comparable in the 3 arms. Urinary TXM was reduced by 35% in both experimental arms. Patients in the thrice-daily arm reported a higher abdominal discomfort score. In conclusion, the currently recommended aspirin regimen of 75 to 100 once daily for cardiovascular prophylaxis appears to be largely inadequate in reducing platelet activation in the vast majority of patients with ET. The antiplatelet response to low-dose aspirin can be markedly improved by shortening the dosing interval to 12 hours, with no improvement with further reductions (EudraCT 2016-002885-30).

Pharmacokinetic, Pharmacodynamic, and Safety/Tolerability Profiles of CG100649, a Novel COX-2 Inhibitor: Results of a Phase I, Randomized, Multiple-dose Study in Healthy Korean Men and Women

BackgroundCG100649 is a novel anti-inflammatory drug that is currently under development. CG100649 demonstrates a dual mechanism of action on cyclooxygenase-2 and carbonic anhydrase that may result in favorable treatment effects and few adverse gastrointestinal and cardiovascular events. ObjectiveThe objective of this study was to evaluate the safety, pharmacokinetic, and pharmacodynamic profiles of administering multiple oral doses of CG100649 to healthy Korean volunteers. MethodsThis was a randomized, double-blind, placebo-controlled, multiple ascending oral dose study that was performed on 8 male and 8 female subjects per dose cohort. Each subject was randomly selected to receive either a single loading dose followed by 6 days of once-daily placebo (n = 4; 2 male and 2 female subjects) or CG100649 (n = 12; 6 male and 6 female subjects). Each subject was administered 1 of 3 sequential dose levels (8-mg loading dose + 2 mg/d, 10-mg loading dose + 4 mg/d, or 12-mg loading dose + 8 mg/d). Blood samples for pharmacokinetic analysis were obtained ≤480 hours after the last dose. Blood samples for measuring serum thromboxane B2 (TXB2) and ex vivo lipopolysaccharide-stimulated prostaglandin E2 (PGE2) (markers of cyclooxygenase-1 and cyclooxygenase-2 activity, respectively) and urine samples for measuring prostanoid metabolites were collected ≤21 days after the last dose. ResultsDuring steady state, the median Tmax in blood and plasma after the last dose ranged from 3 to 10 hours and 3.5 to 7.3 hours, respectively. Mean terminal t½ values in blood and plasma ranged from 121 to 203 hours and 100 to 167 hours, respectively. Whole blood concentrations were 50 to 70 times higher than plasma concentrations in all 3 dose cohorts in both male and female subjects. Compared with baseline, serum TXB2 diminished by 68% to 91% at 8 hours after the administration of the last dose in all 3 cohorts (P < 0.001). Ex vivo lipopolysaccharide-stimulated PGE2 was maximally inhibited (89%–96%; P < 0.001) by all 3 dose levels on day 7. Urinary prostacyclin metabolite was inhibited by 64% (P < 0.001) on day 7 (12–24 hours) but only by the highest CG100649 dose. There were no clinically significant drug-related changes in blood pressure between treatment groups. The most frequently encountered adverse events were aphthous stomatitis and dyspepsia. ConclusionsCG100649 was well tolerated and demonstrated a whole blood concentration that is ~50 to 70 times higher than in plasma in these healthy subjects. CG100649 suppressed TXB2 and PGE2 at all 3 doses, and only the highest dose suppressed the urinary excretion of the urinary prostacyclin metabolite.

Eicosanoid Production following One Bout of Exercise in Middle-Aged African American Pre- and Stage 1 Hypertensives

Endothelial dysfunction and a sedentary lifestyle may be involved in the development of hypertension which is proliferative among middle-aged African Americans (AA). Signaling molecules derived from the oxidation of 20-carbon fatty acid molecules known as eicosanoids influence vascular tone. The relationship between aerobic fitness and eicosanoid formation following exercise in middle-aged African American hypertensives is unknown. Purpose. To determine the relationship between aerobic capacity and eicosanoid formation after a bout of moderate-intensity exercise in middle-aged AA hypertensives. Methods. Ten sedentary hypertensive AA underwent 50 min of aerobic exercise at 65% VO2max. Urine was collected for 24 hr on two occasions, prior to testing and immediately following the bout of exercise. Urinary metabolites of prostacyclin (6-keto PGF1α) and thromboxane (11-dTXB2) were measured during the day and night periods by high-performance liquid chromatography (HPLC). Results. 6-keto PGF1α levels significantly increased (P = .04) following the bout of exercise compared to the control day. There was a significant relationship (r = .49, P < .05) between 6-keto PGF1α levels and VO2max during the exercise day. Conclusion. Based on this preliminary study, there appears to be a relationship between aerobic capacity and exercise-induced 6-keto PGF1α production in middle-aged hypertensive AAs. AAs with lower VO2max had lower 6-keto PGF1α formation.

Coxibs strike back

Coxibs strike back

Circulating neutrophils maintain physiological blood pressure by suppressing bacteria and IFNγ-dependent iNOS expression in the vasculature of healthy mice

AbstractWhether leukocytes exert an influence on vascular function in vivo is not known. Here, genetic and pharmacologic approaches show that the absence of neutrophils leads to acute blood pressure dysregulation. Following neutrophil depletion, systolic blood pressure falls significantly over 3 days (88.0 ± 3.5 vs 104.0 ± 2.8 mm Hg, day 3 vs day 0, mean ± SEM, P < .001), and aortic rings from neutropenic mice do not constrict properly. The constriction defect is corrected using l-nitroarginine-methyl ester (L-NAME) or the specific inducible nitric oxide synthase (iNOS) inhibitor 1400W, while acetylcholine relaxation is normal. iNOS- or IFNγ-deficient mice are protected from neutropenia-induced hypotension, indicating that iNOS-derived nitric oxide (NO) is responsible and that its induction involves IFNγ. Oral enrofloxacin partially inhibited hypotension, implicating bacterial products. Roles for cyclooxygenase, complement C5, or endotoxin were excluded, although urinary prostacyclin metabolites were elevated. Neutrophil depletion required complement opsinization, with no evidence for intravascular degranulation. In summary, circulating neutrophils contribute to maintaining physiological tone in the vasculature, at least in part through suppressing early proinflammatory effects of infection. The speed with which hypotension developed provides insight into early changes that occur in the absence of neutrophils and illustrates the importance of constant surveillance of mucosal sites by granulocytes in healthy mice.

Inherited human cPLA2α deficiency is associated with impaired eicosanoid biosynthesis, small intestinal ulceration, and platelet dysfunction

Cytosolic phospholipase A2alpha (cPLA2alpha) hydrolyzes arachidonic acid from cellular membrane phospholipids, thereby providing enzymatic substrates for the synthesis of eicosanoids, such as prostaglandins and leukotrienes. Considerable understanding of cPLA2alpha function has been derived from investigations of the enzyme and from cPLA2alpha-null mice, but knowledge of discrete roles for this enzyme in humans is limited. We investigated a patient hypothesized to have an inherited prostanoid biosynthesis deficiency due to his multiple, complicated small intestinal ulcers despite no use of cyclooxygenase inhibitors. Levels of thromboxane B2 and 12-hydroxyeicosatetraenoic acid produced by platelets and leukotriene B4 released from calcium ionophore-activated blood were markedly reduced, indicating defective enzymatic release of the arachidonic acid substrate for the corresponding cyclooxygenase and lipoxygenases. Platelet aggregation and degranulation induced by adenosine diphosphate or collagen were diminished but were normal in response to arachidonic acid. Two heterozygous single base pair mutations and a known SNP were found in the coding regions of the patient's cPLA2alpha genes (p.[Ser111Pro]+[Arg485His; Lys651Arg]). The total PLA2 activity in sonicated platelets was diminished, and the urinary metabolites of prostacyclin, prostaglandin E2, prostaglandin D2, and thromboxane A2 were also reduced. These findings characterize what we believe is a novel inherited deficiency of cPLA2.

Effects of Etoricoxib and Comparator Nonsteroidal Anti‐Inflammatory Drugs on Urinary Sodium Excretion, Blood Pressure, and Other Renal Function Indicators in Elderly Subjects Consuming a Controlled Sodium Diet

This multicenter, double-blind, randomized, placebo-controlled, parallel-group study assessed renal function during dosing with etoricoxib 90 mg daily, celecoxib 200 mg twice daily, and naproxen 500 mg twice daily. Male and female subjects 60 to 81 years old (n = 85), in sodium balance on a controlled, normal sodium diet, were treated for 15 days. There were no clinically meaningful between-treatment differences in urinary sodium excretion, creatinine clearance, body weight, or serum electrolytes during the 2 weeks of treatment. Etoricoxib and celecoxib had no effect on the urinary thromboxane metabolite, 11-dehydrothromboxane B(2), while significantly decreasing the urinary prostacyclin metabolite, 2,3-dinor-6-keto PGF(1alpha). Decreases were greater for both metabolites following naproxen. Ambulatory systolic blood pressures were significantly higher than placebo for all treatments, with moderately greater increases for etoricoxib relative to other active treatments on day 14. Ambulatory diastolic blood pressures were significantly higher than placebo for etoricoxib and naproxen but not for celecoxib.

Balancing prostanoid activity in the human vascular system

The imbalance theory proposes that arterial thrombosis is dependent on a ratio or balance between the cyclooxygenase (COX)-1-dependent generation of thromboxane in platelets and the COX-2-dependent generation of prostacyclin in the endothelium. Accordingly, by reducing endothelium-derived prostacyclin levels, selective COX-2 inhibitors would increase susceptibility to vasoconstriction, platelet activation and atherothrombosis. This imbalance theory has been frequently used to legitimize the potential for increased cardiovascular risk associated with the use of these agents. Surprisingly, the imbalance theory is based not on human vascular biology but on the analysis of urinary prostacyclin metabolites. In this review, I discuss the theory in the context of direct studies of human vascular biology, which indicate that the imbalance theory is based on incorrect assumptions and is not plausible.

Targeted Cyclooxygenase Gene (Ptgs) Exchange Reveals Discriminant Isoform Functionality

The prostaglandin G/H synthase enzymes, commonly termed COX-1 and COX-2, differ markedly in their responses to regulatory stimuli and their tissue expression patterns. COX-1 is the dominant source of "housekeeping" prostaglandins, whereas COX-2 synthesizes prostaglandins of relevance to pain, inflammation, and mitogenesis. Despite these distinctions, the two enzymes are remarkably conserved, and their subcellular distributions overlap considerably. To address the functional interchangeability of the two isozymes, mice in which COX-1 is expressed under COX-2 regulatory elements were created by a gene targeting "knock-in" strategy. In macrophages from these mice, COX-1 was shown to be lipopolysaccharide-inducible in a manner analogous to COX-2 in wild-type macrophages. However, COX-1 failed to substitute effectively for COX-2 in lipopolysaccharide-induced prostaglandin E2 synthesis at low concentrations of substrate and in the metabolism of the endocannabinoid 2-arachidonylglycerol. The marked depression of the major urinary metabolite of prostacyclin in COX-2 null mice was only partially rescued by COX-1 knock-in, whereas the main urinary metabolite of prostaglandin E2 was rescued totally. Replacement with COX-1 partially rescued the impact of COX-2 deletion on reproductive function. The renal pathology consequent to COX-2 deletion was delayed but not prevented, whereas the corresponding peritonitis was unaltered. Insertion of COX-1 under the regulatory sequences that drive COX-2 expression indicated that COX-1 can substitute for some COX-2 actions and rescue only some of the consequences of gene disruption. Manipulation of COX-2 also revealed a preference for coupling with distinct downstream prostaglandin synthases in vivo. These mice will provide a valuable reagent with which to elucidate the distinct roles of the COX enzymes in mammalian biology.

Effects of physical conditioning on lipids and arachidonic acid metabolites in untrained boys: a longitudinal study

In addition to a variety of lipids, 2 products of the arachidonic acid cascade, prostacyclin and thromboxane, are involved in the pathogenesis of atherosclerosis as a result of their effects on platelet function and on the vascular endothelium. The aim of the present investigation was to ascertain if a sub-maximal 8 week endurance training period followed by a 4 week detraining period would have any effects on high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), triglycerides (TG), 2,3-dinor-6-keto-prostaglandin F(1alpha) (2,3-dinor-6-keto-PGF(1alpha)), the urinary metabolite of prostacyclin, 2,3-dinor-thromboxane B2 (2,3-dinor-TXB2), the urinary metabolite of thromboxane, and the ratios of TC to HDL-C and of 2,3 dinor-6-keto-PGF(1alpha) to 2,3-dinor-TXB2. Thirty-eight boys aged 10-14 were randomly divided into exercise (n = 21) and control (n = 17) groups. The exercise group trained on a bicycle ergometer 4 times/week, 1 h/session, at 80% of their physical working capacity at a heart rate of 170 beats/min (PWC(170)), for 8 weeks. The control group did not participate in any specific physical exercise program. The results showed that relative to the control group, the exercise group had a significant increase in HDL-C and 2,3-dinor-6-keto-PGF(1alpha) concentrations at the end of the 4th (p < 0.05 and p < 0.001, respectively) and the 8th week (p < 0.01 and p < 0.001) of training, respectively; a significant increase in the 2,3 dinor-6-keto-PGF(1alpha) - 2,3-dinor-TXB2 ratio (p < 0.05 and p < 0.01 at the same intervals); a significant decrease in TG at the end of the 8th week of training (p < 0.05); and a significant decrease in the TC--HDL-C ratio at the end of the 4th (p < 0.05) and 8th weeks of training (p < 0.001).

Early vasodilator response to anodal current application in human is not impaired by cyclooxygenase-2 blockade

It is generally acknowledged that cutaneous vasodilatation in response to monopolar galvanic current application would result from an axon reflex in primary afferent fibers and the neurogenic inflammation resulting from neuropeptide release. Previous studies suggested participation of prostaglandin (PG) in anodal current-induced cutaneous vasodilatation. Thus the inducible cyclooxygenase (COX) isoform (COX-2), assumed to play a key role in inflammation, should be involved in the synthesis of the PG that is released. Skin blood flow (SkBF) variations induced by 5 min of 0.1-mA monopolar anodal current application were evaluated with laser-Doppler flowmetry on the forearm of healthy volunteers treated with indomethacin (COX-1 and COX-2 inhibitor), celecoxib (COX-2 inhibitor), or placebo. SkBF was indexed as cutaneous vascular conductance (CVC), expressed as percentage of heat-induced maximal CVC (%MVC). Urinalyses were performed to test celecoxib treatment efficiency. No difference was found in CVC values at rest: 14.3 +/- 4.0, 11.9 +/- 3.2, and 10.9 +/- 2.0% MVC after indomethacin, celecoxib, and placebo treatment, respectively. At 10 min after the onset of anodal current application, CVC values were 22.2 +/- 4.9% MVC (not significantly different from rest) with indomethacin, 85.7 +/- 15.3% MVC (P < 0.001 vs. rest) with celecoxib, and 70.4 +/- 13.1% MVC (P < 0.001 vs. rest) with placebo. Celecoxib significantly depressed the urinary prostacyclin metabolite 6-keto-PGF(1alpha) (P < 0.05 vs. placebo). Indomethacin, but not celecoxib, significantly inhibited the anodal current-induced vasodilatation. Thus, although they are assumed to result from an axon reflex in primary afferent fibers and neurogenic inflammation, these results suggest that the early anodal current-induced vasodilatation is mainly dependent on COX-1-induced PG synthesis.

Cyclooxygenase-2 promotes early atherosclerotic lesion formation in LDL receptor-deficient mice.

Atherosclerosis has features of an inflammatory disease. Because cyclooxygenase (COX)-2 is expressed in atherosclerotic lesions and promotes inflammation, we tested the hypotheses that selective COX-2 inhibition would reduce early lesion formation in LDL receptor-deficient (LDLR-/-) mice and that macrophage COX-2 expression contributes to atherogenesis in LDLR-/- mice. Treatment of male LDLR-/- mice fed the Western diet with rofecoxib or indomethacin for 6 weeks resulted in significant reductions in atherosclerosis in the proximal aorta (25% and 37%) and in the aorta en face (58% and 57%), respectively. Rofecoxib treatment did not inhibit platelet thromboxane production, a COX-1-mediated process, but it significantly reduced the urinary prostacyclin metabolite 2,3-dinor-6-keto-PGF1alpha. Fetal liver cell transplantation was used to generate LDLR-/- mice null for expression of the COX-2 gene by macrophages. After 8 weeks on the Western diet, COX-2-/- --> LDLR-/- mice developed significantly less (33% to 39%) atherosclerosis than control COX-2+/+ --> LDLR-/- mice. In both the inhibitor studies and the transplant studies, serum lipids did not differ significantly between groups. The present studies provide strong pharmacological and genetic evidence that COX-2 promotes early atherosclerotic lesion formation in LDLR-/- mice in vivo. These results support the potential of anti-inflammatory approaches to the prevention of atherosclerosis.

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-PGF1 αand 2,3-dinor-6-keto-PGF1 α) and thromboxane A2(TxB2and 2,3-dinor-TxB2) 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-PGF1 α/ TxB2-ratio as well as the 2,3-dinor-6-keto-PGF1α/ 2,3-dinor-TxB2-ratio did not significantly change in pregnancy.Conclusion:Prostacyclin and thromboxane do not seem to play an important role in sodium balance during pregnancy.

Solid- and liquid-phase extraction for the gas chromatographic–tandem mass spectrometric quantification of 2,3-dinor-thromboxane B 2 and 2,3-dinor-6-oxo-prostaglandin F 1α in human urine

Whole body synthesis of thromboxane A 2 is best assessed by quantifying non-invasively its major urinary metabolite, i.e., 2,3-dinor-thromboxane B 2 (2,3-dn-TxB 2), by gas chromatography–mass spectrometry (GC–MS) or GC–tandem MS. Methods based on these techniques usually require a series of extraction and purification procedures including solid-phase extraction (SPE) and thin-layer chromatography (TLC) or liquid chromatographic separation of authentic or derivatized 2,3-dn-TxB 2. Taking advantage of the inherent accuracy of GC–tandem MS and the high selectivity of the extraction of methoximated 2,3-dn-TxB 2 on phenylboronic acid SPE cartridges we developed a method that involves only SPE steps prior to quantification by GC–tandem MS. The method was validated by performing in parallel an additional TLC step. Method mean accuracy and precision were of the order of 103% and 95%, respectively. The method allows furthermore co-processing of the same urine sample to quantify accurately and rapidly the major urinary metabolite of prostacyclin, i.e., 2,3-dn-6-oxo-prostaglandin (PG) F 1α, by GC–tandem MS. The limit of detection of the method was below each 5 pg of 2,3-dn-TxB 2 and 2,3-dn-6-oxo-PGF 1α per 5 ml of urine. Our study suggests that dinor metabolites of isothromboxanes and isoprostacyclins are not abundantly present in human urine.

Is proteinuric pre-eclampsia a different disease in primigravida and multigravida?

This study aimed to identify if the clinical features of proteinuric pre-eclampsia or the biochemical markers of endothelial dysfunction associated with this syndrome are altered according to parity in a direction that would suggest a different pathophysiology. Groups of 27 primigravid and 35 multigravid women with pre-eclampsia (defined as blood pressure &gt; 140/90 mmHg and 2+ proteinuria) were studied ante-partum, and at 6 weeks and 6 months post-partum. Clinical markers of severity of pre-eclampsia, including blood pressure, markers of renal, hepatic and coagulatory function, and biochemical markers of endothelial dysfunction were measured. Fetal outcome was assessed by birthweight and birthweight percentile. Ante-partum systolic blood pressure was 10 mmHg higher in the primigravida, and this difference was independent of age and anti-hypertensive medication. Analysis of systolic blood pressure before and after delivery showed the primigravid women to have elevated systolic blood pressure over the whole time period (P&lt; 0.01). The primigravid women had more severe hepatic dysfunction, with elevated aspartate aminotransferase levels, but plasma creatinine, proteinuria, platelet counts and haematocrit were similar, indicating that renal and coagulatory function and plasma volume were affected to the same extent in the two groups and were independent of parity. Birthweight was similar in the two groups, and the percentage of infants weighing less than the 10th centile for gestation was also similar. Biochemical markers of endothelial dysfunction, assessed by measuring the urinary prostacyclin metabolite 2,3-dinor-6-oxo-prostaglandin F1α and plasma endothelin 1, did not differ according to parity. There were no differences in a number of other biochemical markers of pre-eclampsia, including plasma albumin, uric acid, triacylglycerol, and total, low-density lipoprotein and high-density lipoprotein cholesterol. Basophil, monocyte and lymphocyte counts were elevated before delivery in primigravid women with pre-eclampsia. The differences in lymphocyte counts persisted post-partum. Further studies are required to clarify the role, if any, of monocytes, basophils and lymphocytes in the pathophysiology of pre-eclampsia. In conclusion, the elevated systolic blood pressure and raised aspartate aminotransferase levels observed in primigravida suggest a more severe form of pre-eclampsia. The lack of differences in birthweight and other biochemical and endothelial markers of severity of pre-eclampsia do not suggest a different pathophysiology; however, the persistently higher white cell counts in the primigravid pre-eclamptics are of interest, and might reflect differences in immune responses in the two groups. We suggest that studies of the pathophysiology of pre-eclampsia should include multigravida, as long as there is adequate post-partum follow-up to exclude underlying disease.

Is proteinuric pre-eclampsia a different disease in primigravida and multigravida?

This study aimed to identify if the clinical features of proteinuric pre-eclampsia or the biochemical markers of endothelial dysfunction associated with this syndrome are altered according to parity in a direction that would suggest a different pathophysiology. Groups of 27 primigravid and 35 multigravid women with pre-eclampsia (defined as blood pressure >140/90 mmHg and 2+ proteinuria) were studied ante-partum, and at 6 weeks and 6 months post-partum. Clinical markers of severity of pre-eclampsia, including blood pressure, markers of renal, hepatic and coagulatory function, and biochemical markers of endothelial dysfunction were measured. Fetal outcome was assessed by birthweight and birthweight percentile. Ante-partum systolic blood pressure was 10 mmHg higher in the primigravida, and this difference was independent of age and anti-hypertensive medication. Analysis of systolic blood pressure before and after delivery showed the primigravid women to have elevated systolic blood pressure over the whole time period (P<0.01). The primigravid women had more severe hepatic dysfunction, with elevated aspartate aminotransferase levels, but plasma creatinine, proteinuria, platelet counts and haematocrit were similar, indicating that renal and coagulatory function and plasma volume were affected to the same extent in the two groups and were independent of parity. Birthweight was similar in the two groups, and the percentage of infants weighing less than the 10th centile for gestation was also similar. Biochemical markers of endothelial dysfunction, assessed by measuring the urinary prostacyclin metabolite 2, 3-dinor-6-oxo-prostaglandin F(1alpha) and plasma endothelin 1, did not differ according to parity. There were no differences in a number of other biochemical markers of pre-eclampsia, including plasma albumin, uric acid, triacylglycerol, and total, low-density lipoprotein and high-density lipoprotein cholesterol. Basophil, monocyte and lymphocyte counts were elevated before delivery in primigravid women with pre-eclampsia. The differences in lymphocyte counts persisted post-partum. Further studies are required to clarify the role, if any, of monocytes, basophils and lymphocytes in the pathophysiology of pre-eclampsia. In conclusion, the elevated systolic blood pressure and raised aspartate aminotransferase levels observed in primigravida suggest a more severe form of pre-eclampsia. The lack of differences in birthweight and other biochemical and endothelial markers of severity of pre-eclampsia do not suggest a different pathophysiology; however, the persistently higher white cell counts in the primigravid pre-eclamptics are of interest, and might reflect differences in immune responses in the two groups. We suggest that studies of the pathophysiology of pre-eclampsia should include multigravida, as long as there is adequate post-partum follow-up to exclude underlying disease.

Urinary prostacyclin metabolites in patients with IgA nephropathy

Background. Urinary 6-keto-prostaglandin F1α (6kPGF) is an index of renal prostacyclin (PGI2) synthesis, while urinary 2,3-dinor-6-keto-prostaglandin F1α (23d6kPGF) reflects extrarenal PGI2 synthesis. We therefore examined the relationship between the urinary excretion of PGI2 metabolites and the deterioration of renal function and histopathological findings.

Effects of smoking on prostacyclin formation and platelet aggregation in users of oral contraceptives

Objective: The aim of this review was to determine which subgroups within the population of smokers and oral contraceptive users are at especially elevated risk for thromboembolic events. Study Design: This review covers 10 articles published between 1981 and 1996 that examined the effects of smoking and oral contraceptive use, in conjunction or independently, on factors affecting the coagulation pathway, particularly the expressions of prostacyclin and thromboxane. Results: Heavy, prolonged, or current nicotine use was associated with a reduction in the urinary metabolite of prostacyclin (prostaglandin I 2 ) in oral contraceptive users. Smoking and increased excretion of thromboxane were also linked, and in 1 study the effect was dose related. These changes were associated with increased platelet aggregation. Oral contraceptive use and concurrent smoking increased the risk of acute myocardial infarction by a ratio of 10.1. Although most of this risk was seen among smokers who used second-generation oral contraceptives (odds ratio 11.1), with a much reduced odds ratio for smokers who used third-generation oral contraceptives (odds ratio 3.1), the study was not controlled for estrogen dose. A reduction in myocardial infarction risk compared with that in the 1970s was seen for all oral contraceptive users, probably because of the reduced hormonal doses in current preparations. Conclusion: Smoking, not oral contraceptive use, constitutes the greater cardiovascular risk. However, cigarette smoking and oral contraceptive use act synergistically to increase the risk of thromboembolic events. Differences in oral contraceptive formulations may mitigate the increased risk resulting from concurrent smoking and use of oral contraceptives, but whether the progestin component or the lowered estrogen dose is responsible is unclear. (Am J Obstet Gynecol 1999;180:S364-8.)

Blood Pressure and Vasoactive Hormones in Mild Preeclampsia and Normal Pregnancy

Objective: Changes in vasoactive hormones are reported to play an important role in the pathogenesis of preeclampsia linking placental hypoperfusion with hypertension, systemic disease, and proteinuria. We, therefore, studied diurnal patterns of vasoactive hormones in mild preeclampsia.Methods: Venous blood samples were drawn every 2 h over 25 h for measurements of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), norepinephrine, renin activity, and aldosterone and two urine collections (12 h each) for stable prostaglandin metabolite measurements. The patients were nine women with mild preeclampsia and, for comparison, nine control women matched for gestation and parity.Results: Women with mild preeclampsia had higher norepinephrine levels throughout 25 h, and lower systemic prostacyclin production as measured by the urinary 2,3-dinor-6-keto PGF1α excretion during the daytime. Plasma endothelin and ANP and BNP concentrations tended to be higher throughout 25 h in preeclampsia, but differences between the two groups did not reach levels of statistical significance. Plasma renin activity and aldosterone did not differ between the groups. Whereas control women exhibited a diurnal variation in plasma norepinephrine, ANP, BNP, and aldosterone, and in both urinary prostacyclin and thromboxane A2 metabolites, this was less distinct or absent in patients with mild preeclampsia.Conclusions: We conclude that mild preeclampsia is associated with elevated plasma norepinephrine levels, lower systemic daytime production of prostacyclin, and blunting of the normal diurnal variation for a number of indices including plasma levels of BNP, ANP, norepinephrine, and aldosterone, and urinary prostacyclin metabolites.