Vaginal and abdominal delivery increases maternal urinary 6-keto-prostaglandin F1α excretion

Summary. To study the role of the antiaggregatory and vasodilatory prostacyclin (PGI₂) during human delivery, serial urine samples collected from 13 women delivered vaginally and from eight delivered abdominally were assayed for 6-keto-prostaglandin F_1α (6-keto-PGF_1α a breakdown product of PGI₂) by high-performance-liquid-chromatography and radioimmunoassay. In women delivered vaginally the mean urinary 6-keto-PGF_1α concentration was 41.9 (SE 8.3) ng/mmol creatinine, before the onset of labour and increased progressively to a maximum of 186.5 (SE 47.6) ng/mmol creatinine 2 h after delivery irrespective of the use of oxytocin and epidural analgesia. In women delivered by caesarean section under epidural anaesthesia, the urinary 6-keto-PGF_1α rose from 33.4 (SE 4.2) ng/mmol creatinine to 2153 (SE 314) ng/mmol creatinine 2 h after section. In both groups the increased levels had fallen by 24 h postpartum to levels below those found before delivery. In neonatal urine 6-keto-PGF_1α concentrations were some 12–30 times higher than those in postpartum urine. Thus, vaginal and abdominal delivery is accompanied by significant increases in maternal PGI₂ release, perhaps in the myometrium and/or intrauterine tissues. This may be of significance in the regulation of fetoplacental blood flow and in the prevention of intra- and postpartum thrombosis.     

Effect of vacuum curettage on the concentrations of plasma 6-keto-prostaglandin Flα and serum thromboxane B2

Summary. Serial plasma samples collected before and after vacuum curettage followed by methylergometrine injection in 10 women were assayed for 6-keto-prostaglandin F_lα (6-keto-PGF^1α). The mean 6-keto-PGF_lα concentration was 97.2 (SE 8.8) pg/ml before cervical dilatation. The concentration rose to 128.2 (SE 13.5) pg/ml (P < 0.10) immediately and to 133.3 (SE 17.8) pg/ml (P < 0.05) 1 h after curettage and returned to the initial value within 5 h. Neither methylergometrine nor anaesthesia, nor non-gynaecological surgery, caused changes in the level of plasma 6-keto-PGF_lα. The capacity of the platelets to produce thromboxane A² during spontaneous clotting of blood did not change during vacuum curettage, anaesthesia and non-gynaecological surgery, nor after methylergometrine. The evidence suggests that the pregnant myometrium and/or intrauterine tissues capable of generating prostacyclin (PGI₂) in vitro may release PG1₂ also in vivo .     

Are leukotrienes involved in human uterine contractility?

Summary. The effects of leukotrienes (LT) on the contractility of human and rat myometrial strips in vitro were compared with the effects of prostaglandins (PGs) and oxytocin. Preparations of human myometrial membranes were investigated for the presence and characteristics of LTC₄ receptors. Neither the peptido-leukotrienes (LTC₄, LTD₄, LTE₄) nor LTB₄ had any consistent effect, stimulatory or inhibitory, on human pregnant or non-pregnant myometrium, at doses up to 1·25 μM; nor did they have any effect in rat non-pregnant myometrium. As expected, PGE₂, PGF_2α (0·3 μM) and oxytocin (5 nM) stimulated human pregnant myometrium. PGF_2α stimulated and PGE₂ inhibited human non-pregnant myometrium but oxytocin had no effect; all three compounds stimulated rat non-pregnant myometrium. The binding of ³H-LTC₄ to human myometrium was specific (LTC₄> LTD₄ >>> LTE₄, LTB₄, PGE₂, PGF_2α, arachidonic acid) but of low affinity compared with the binding of ³H-PGE₂ to the same membrane preparations. These data support the view that leukotrienes have little direct influence on myometrial contractility.     

The effects of metabolic inhibition on intracellular calcium and contractility of human myometrium

Objective Hypoxia occurs in the uterus during labour and may contribute to dysfunctional labours. We wanted to establish its effects on pregnant human myometrium and elucidate the mechanisms involved.
Design Scientific study.
Setting University Hospital and laboratories.
Population or Sample Term pregnant women.
Methods We measured contractions and intracellular [Ca²⁺] ([Ca²⁺]_i), in biopsies from term pregnant women undergoing elective caesarean section, and used cyanide to block oxidative phosphorylation.
Main outcome measures Changes in contractility and calcium.
Results Although basal levels of [Ca²⁺]_i and tone rose, spontaneous and agonist-induced Ca²⁺ transients and phasic contractions were rapidly reduced and abolished by cyanide. Neither stimulation of the uterus with oxytocin nor the Ca channel agonist, Bay K8644, prevented the changes produced by cyanide. The tonic force produced by depolarising the myometrium was also decreased by cyanide, but slowly recovered towards control levels, whereas [Ca²⁺]_i was maintained throughout. Similar data were obtained when nitrogen, rather than cyanide, was applied to the depolarised uterus.
Conclusions Impairment of oxidative phosphorylation is a potent depressor of phasic activity in human myometrium, irrespective of how it is produced, and our data suggest its effects lie at and beyond the surface membrane. Stimulation of the hypoxic uterus was not effective, which may explain the unpredictability of oxytocin application in some dysfunctional labours.     

Decreased prostacyclin production by placental cells in culture from pregnancies complicated by fetal growth retardation

Summary. Production of prostacyclin (PGI₂) in vitro by human placental cells from pregnancies complicated by fetal growth retardation was significantly reduced compared with that in placental cells from normal pregnancies of either matched gestation or at term. This appeared to be due to a reduction of synthesis of PGI₂ rather than to any alteration in the rate of its enzymic metabolism. Addition of oestradiol and progesterone increased PGI₂ production by cells from pregnancies with fetal growth retardation in a similar manner to that by cells from first trimester pregnancies, implying that the placental cells are not irreversibly damaged by ischaemia. The decreased PGI₂ production by cells of trophoblastic origin may be an aetiological factor in the thrombotic occlusion of the uteroplacental circulation which impairs fetal growth.     

Production of prostacyclin, 6-keto-PGFlα and thromboxane B2 by human umbilical vessels increases from the placenta towards the fetus

Summary. The aim of this study was to investigate the production of prostacyclin (PGI₂) and thromboxane B₂ (TXB₂) by incubated samples of umbilical arteries and veins taken at different distances (2, 10,20,30 cm) from the placenta to provide additional information relevant to the haemodynamics of umbilical blood flow. The production of PGI₂, and 6-keto-PGF_1α (the stable metabolite of PGI₂), was higher in both veins and arteries as the distance from the placenta at which the vessels were sampled was increased. A similar correlation between production by venous rings and distance from the placenta was observed for TXB₂, but there was no apparent gradient of TXB₂ production by the samples of arterial rings. No statistically significant variations were discernible in the ratio of 6-keto-PGF_1α:TXB₂ (∼50 in the veins and ∼20 in the arteries) in relation to the sampling distance. The significance of these high ratios is discussed in relation to umbilical blood flow and fetal well-being and development.     

Beta-3 versus beta-2 adrenergic agonists and preterm labour: in vitro uterine relaxation effects

Objective 1. To investigate the effects of the selective beta-3 adrenoreceptor agonist, BRL 37344, on human pregnant myometrial contractility in vitro . 2. to compare these effects with those of the beta-2 adrenoreceptor agonist, ritodrine.
Methods Isometric tension recording was performed under physiological conditions in isolated myometrial strips from biopsies obtained at elective caesarean section. Following pre-incubation with oxytocin (  10^-9 M  ), the effects of cumulative additions of BRL 37344 or ritodrine (  10^-8–10^-3.5 M  ) on myometrial contractility were investigated. Results were expressed as  -log EC₅₀ (pD₂)  and mean maximal inhibition achieved for both drug compounds.
Results BRL 37344 exerted a concentration dependant relaxant effect on myometrial contractions in all strips exposed [pD₂, 7.26 (0.48) (SEM); mean maximal inhibition 61.98 (4.89%);   n = 6  ]. Similarly, ritodrine exerted a concentration dependant inhibition of myometrial contractility in all strips exposed [  pD₂= 7.40 (0.28)  ; mean maximal inhibition 59.49 (3.97%);   n = 6  ]. There was no significant difference between calculated pD₂ values (   P = 0.65  ) or mean maximal inhibition achieved (   P = 0.79  ).
Conclusions The beta-3 adrenoreceptor agonist BRL 37344 induced relaxation of human myometrial contractions with similar potency to that of the most commonly used tocolytic agent ritodrine. This raises the possibility that the novel beta-3 adrenoreceptor agonists may have potential as therapeutic agents for human preterm labour. In view of their reported reduced cardiovascular side effects their potential clinical use requires further evaluation.     

Primary and myoma-associated menorrhagia: role of prostaglandins and effects of ibuprofen

Summary. The release of 6-keto-prostaglandin F_1α(6-keto-PGF_1α), a metabolite of prostacyclin (PGI₂) and thromboxane B2 (TxB2), a metabolite of thromboxane A2 (TxA2), was estimated in endometrial biopsies taken from 12 menorrhagic and 12 healthy women during the luteal phase of the cycle. The releases of 6-keto-PGF_1α and TxB2 were normal, but the ratio TxB2/6-keto-PGF_1α was inversely related to menstrual blood loss in women with measured menstrual blood loss exceeding 70 ml. In the second part of the study, 24 women with excessive menstrual bleeding (13 with primary menorrhagia, 10 with uterine fibro-myomas, one with haemostatic factor VIII deficiency) were treated at random with ibuprofen (600mg/day and 1200mg/day) and with a placebo. Ibuprofen 1200 mg/day reduced (P<0.01) median blood loss from 146 ml (range 71–374 ml) to 110 ml (30–288 ml) in primary menorrhagia but had no effect on blood loss in women with uterine fibroids and factor VIII deficiency. Blood loss was normal in six women and was not affected by ibuprofen. Thus, our data suggest that there is a PGI₂ dominance in the endometrium of patients with menorrhagia. In addition, primary, but neither fibromyoma nor coagulation defect-associated menorrhagia, can be treated by ibuprofen.     

Amniotic fluid prostaglandins do not reflect human fetal lung maturation

Summary. Experimental data suggest the involvement of classic prostaglandins (PG), prostacyclin (PGI,) and thromboxane A₂ (Tx A₂ ) in fetal pulmonary development. To explore this possibility in man, we assayed serial amniotic fluid samples from 33 women for 13, 14 -dihydro-15-keto-PGF_2α (M-PGF_2α a metabolite of PGF_2α), 6-keto-PGF_1α (a breakdown product of prostacyclin (PGI₂)), and thromboxane B₂ (a metabolite of TxA₂) as well as for the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol. No difference in these prostanoids was seen between the samples with the immature (< 2) or mature 2) L/S ratio, or between the samples with undetectable or detectable phosphatidylglycerol. The L/S ratio matured in 16 women and phosphatidylglycerol became detectable in 19 women during serial smpling, but even in these women the changes in the amniotic fluid prostanoids were inconsistent. It is concluded that the amniotic fluid M-PGF_2α, 6-keto-PGF_1α, and TxB₂ do not reflect fetal pulmonary maturity.     

Thromboxane A2 and prostacyclin levels in molar pregnancy

Summary. Plasma levels of thromboxane (TX) A₂ and prostacyclin (PGI₂), as measured by radioimmunoassay of their respective stable metabolites TXB₂ and 6–keto PGF_1α, were studied in six molar pregnancies immediately before, immediately following and 24 h after evacuation of the uterus. The mean (SD) levels for TXB₂ were 150 (41), 137 (32) and 125 (25) pg/ml respectively, and for 6–keto PGF_1α the respective values were 225 (52), 226 (127) and 213 (49) pg/ml. There was no significant difference in the levels of prostanoids between the samples taken at the various time intervals. The concentration of these prostanoids in molar intravesicular fluid was also determined. Their respective mean (SD) pg/ml values were 3682 (760) for TXB₂ and 2969 (744) for 6–keto PGF_1α. In 15 normal pregnancies of equivalent gestation, the mean amniotic fluid levels of TXB₂ and 6–keto PGF_lα were 34 (17) and 146 (86) pg/ml respectively. The ability of molar trophoblast to generate the prostanoids from [¹⁴C]arachidonic acid in vitro was also demonstrated. Mean (SD) values for TXB₂ and 6-keto PGF_1α were 12.2 (2.6) and 13.2 (1.8) pg/mg protein/min, respectively. It is likely that the high concentrations of prostanoids in vesicular fluid reflect the synthesizing ability of the villus vesicles. The mole contributes little to the circulatory prostanoids possibly because its villi are deficient in blood circulation.     

Primary dysmenorrhoea: the importance of both prostaglandins E2 and F2α

Summary. Menstrual fluid was collected in a contraceptive diaphragm from 16 women with primary dysmenorrhoea and 12 matched control subjects without dysmenorrhoea. Prostaglandins F_2α (PGF_2α), E₂ (PGE₂) and 6-oxo-prostaglandin F_1α (6-oxo-PGF_lα) were extracted and measured using gas-chromatography: mass spectrometry (GC:MS). The concentrations of both PGF_2α and PGE₂ were higher on days 1 and 2 in the dysmenorrhoea group than in the control group and the concentration of PGF_2α was higher on day 1 than on day 2 in the dysmenorrhoea group. The concentrations of 6-oxo-PGF_1α (the stable metabolite of PGI₂) were low in both groups. These results confirm suggestions that PGF_2α is important in the aetiology of dysmenorrhoea and also indicate that PGE₂ may be involved.     

Topographical distribution of prostaglandin E receptors in human myometrium

Summary. The binding of radiolabelled prostaglandin (PG) F_2α and PGE₂ by human myometrium was measured in vitro and the distribution and characteristics of the binding sites in non-pregnant and pregnant uteri were studied. PGF_2α binding sites were of low affinity (Kd 30 nM) and could be occupied by PG of the E series with higher affinity than PGF_2α itself. PGE binding sites were of high affinity (Kd 1·5 nM) and highly specific for PG of the E series, suggesting that they represent true PGE receptors. The concentration of PGE receptors was higher in nonpregnant than in pregnant uteri at term. In non-pregnant uteri the concentration of PGE receptors was highest in the fundus and decreased towards the cervix; in term pregnant uteri the concentration was constant in all areas. In both non-pregnant and pregnant uteri there was a significantly lower PGE binding affinity in cervix than in myometrium from the fundus-corpus area. The concentrations and affinity of PGE receptors were similar during the proliferative and secretory phases of the menstrual cycle and were not influenced by age of the patient. PGE receptors were not influenced by the presence or absence of primary dysmcnorrhoca but appeared to be increased in unexplained menorrhagia.     

Regional differences in vascular responses in the human uterus

Summary. Tissue specimens from the fundus, isthmus and distal cervix were obtained from 14 women at hysterectomy at various phases of the menstrual cycle. Ring preparations of small intramyomctrial and intracervical arteries were dissected and mounted in organ baths; isometric tension was recorded and responses to contractile agents were studied. The amplitude of responses to K⁺ (124mmol/l) of the vessel preparations ranked fundus isthmus > cervix. While similar pD₂ values for noradrenaline (NA) were found, the E_max values ranked cervix isthmus fundus (cervix > fundus). The pD₂ values for arginine-vasopressin (AVP) showed minor differences, while the E_max values for this peptide ranked fundus isthmus cervix (fundus > cervix). Arteries from the fundus and isthmus displayed weak, inconsistent contractile responses to prostaglandin F_2α, but more pronounced contractions were induced by this prostanoid in arterial preparations from the distal cervix. The results suggest regional differences in vascular mechanical responses to endogenous vasoactive agents in the human uterus.     

Circulating antithrombins in pregnancy

Summary. In a cross-sectional study circulating levels of antithrombins, antithrombin III¹α-antitrypsin and α₂-macroglobulin were measured in groups of 20 women before pregnancy, during each trimester and post partum . Blood levels of antithrombin III were signicantly lower, α¹ antitrypsin higher and %aL₂-macroglobulin no different when compared with those of the non-pregnant and puerperal states. These findings suggest that there may be not only an increase in total antithrombin production, but also a qualitative change in antithrombin'activity', the principal protein during pregnancy being α¹-antitrypsin.     

The effect of the antiprogestin RU 486 on uterine contractility and sensitivity to prostaglandin and oxytocin

Summary. The effect of RU 486, a steroid acting as an antiprogestin at the receptor level, on uterine contractility and sensitivity to the prostaglandin analogue, 16-phenoxy-PGE₂ methyl sulfonylamide (16-phe-noxy-PGE₂) and to oxytocin was studied in 29 women in early pregnancy. Seven untreated women at the same stage of pregnancy served as controls. In the untreated women no spontaneous uterine contractility was recorded and the response to 0.25 mg 16-phenoxy-PGE, was characterized by an increase in uterine tonus with superimposed irregular contractions of low amplitude. Treatment with 25 mg RU 486 twice daily resulted in the appearance of regular uterine contractions at 24 h in two out of five patients and in all patients at 36, 48 and 72 h after the start of RU 486 treatment. The withdrawal of progesterone influence changed the inactive early pregnant uterus into an active organ. Administration of 16-phenoxy-PGE₂ caused an obvious stimulation of both frequency and amplitude of the contractions. In addition, the significantly increased sensitivity to the prostaglandin analogue, but not to oxytocin, was already apparent 24 h after the start of RU 486 treatment. We have previously shown that the addition of one intramuscular injection of 16-phenoxy-PGE₂ on the fourth day of treatment with RU 486 (25 mg twice daily) significantly increased the abortifacient effect of the antiprogestin during early pregnancy. The present study suggests that a shorter treatment may be possible.     

Distribution of prostaglandin endoperoxide synthase and prostacyclin synthase in the late pregnant uterus

Summary. Prostacyclin (PGI²) synthase and prostaglandin endoperoxide synthase (cyclo-oxygenase; PGH synthase) were measured with specific immunoradiometric assays in myometrial microsomes from different areas of a primigravid uterus at 34 weeks gestation. PGH synthase concentrations increased significantly from fundus toward lower segment ( P <0·005), but that trend did not apply to PGI² synthase concentrations, which were significantly higher on the placental than on the non-placental side of the uterus ( P <0·005). PGI² synthase concentrations showed no further increase with increasing proximity to the placental bed. In myometrium underneath the placental bed there was an inverse relation between the PGH and PGI² synthase concentrations ( r =0·86; P <0·0l) which did not apply to other regions of the uterus. The data suggest that local rather than general mechanisms control uterine PGH and PGI² synthase concentrations, and that uterine prostaglandin and PGI² production strongly depend on anatomical relations that have been neglected in previous studies on uterine prostaglandin biosynthesis.     

Determinants of umbilical cord arterial 8-iso-prostaglandin F2alpha concentrations

Objective To determine the concentration of 8-isoPGF_2α in cord blood as a measure of oxidative stress during labour, and to compare them with other established parameters of in vivo lipid peroxidation and with the acid-base status of the newborn.
Method Umbilical cord arterial and venous blood samples were collected from 81 singleton term deliveries for determination of 8-isoPGF_2α, malondialdehyde and organic hydroperoxides. In addition, metabolites derived from the oxidative metabolism of purines during hypoxia-reoxygenation and routine cord blood of oxygen saturation, pH, pO₂, pCO₂, HCO₃ and base excess were measured.
Results Arterial concentrations of 8-isoPGF_2α were significantly higher in cases with fetal distress, tight nuchal cord (   P < 0.001  ), the umbilical coiling index, and male sex (   P < 0.05  ) (R²= 0.48). No correlation was found with any parameter of acid-base status. In arterial and venous blood the concentrations of organic hydroperoxides and hypoxanthine significantly correlated with the fetal nuchal cord (   P < 0.001  ) (R²= 0.26 and 0.16, respectively).
Conclusion Our findings indicate that 8-isoPGF_2α in cord arterial blood is a suitable parameter to quantify a possible oxidative stress in the fetus during labour. Measurements of the F₂-isoprostane concentrations in cord blood at labour provide a clinically useful method to assess the perinatal outcome.     

Maternal plasma prostaglandin E2 metabolite levels during human pregnancy and parturition

Summary. Because of methodological problems associated with the measurement in biological fluids of both prostaglandin E₂ (PGE₂) and its unstable principal circulating metabolite 13,14-dihydro-15-keto-PGE₂ (PGEM), there is little reliable information on these prostaglandins in human pregnancy and parturition. The recent discovery of a stable PGEM degradation product 11-deoxy-13,14-dihydro-15-keto-11β, 16-cyclo-PGE₂ (bicyclo-PGEM) has provided a means of studying endogenous plasma levels of PGEM which circumvents the problems encountered with direct measurements of PGE₂ and PGEM. Using a radioimmunoassay for bicyclo-PGEM we have therefore determined maternal peripheral plasma PGE₂ metabolite levels during human gestation. PGE₂ metabolite levels did not alter significantly during the second or third trimesters nor during labour. This contrasts with maternal peripheral plasma levels of the principal circulating metabolite of PGF_2α 13,14-dihydro-15-keto-PGF_2α (PGFM) which increases several fold during labour. Compared t o PGE₂ therefore. PGF_2α may be quantitatively the more significant prostaglandin associated with human parturition.     

Prognostic Value of Plasma Oestradiol-17β and Human Placental Lactogen in High-risk Pregnancies

Summary: Serial estimations of plasma oestradiol-17(E₂) and human placental lactogen (HPL) were made in 58 high-risk pregnancies. In pregnancies complicated by marked hypertension, intrauterine growth retardation, and intra-uterine death, plasma E₂ did not reflect fetal well-being accurately, unlike HPL which was accurate in predicting fetal outcome. In diabetic pregnancy, plasma E₂ and HPL levels were similar to those found in normal pregnancy.     

Standard dose cisplatin with rhG-CSF allows sufficient harvesting of PBSC for autotransplantation in patients with ovarian cancer

We have investigated the feasibility of a program of autologous peripheral blood stem cell (PBSC) harvesting and transplantation in patients with ovarian cancer. From four patients, PBSC was collected during hematopoietic recovery following aplasia induced by standard dose cisplatin 70 mg m⁻² with etoposide 500 mg m⁻² or adriamycin 40 mg m⁻² and cyclophosphamide 500 mg m⁻² plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) at a dose of 75 µg day⁻¹ given intracutaneously. In apheresed patients, we harvested an average of 2.31 × 10⁵ kg⁻¹ colony-forming unit granulocyte/macrophage (range 0–5.22) per cycle. Low hematologic toxicity was observed during the hematopoietic reconstitution of the four patients subjected to PBSC support with G-CSF (5 µg kg⁻¹ day⁻¹ given by continuous infusion) after high-dose chemotherapy (carboplatin 900 mg m⁻² and etoposide 900 mg m⁻²). The patients were not evaluable for a response because we performed consolidated high-dose chemotherapy. However, no evidence of recurrence has been observed 11.8 months (range 2–19) after high-dose chemotherapy. We can conclude that standard dose cisplatin in combination with etoposide or adriamycin and cyclophosphamide plus rhG-CSF allows sufficient harvesting of PBSC for autotransplantation in patients with ovarian cancer.