Comparison of intravenous oxytocin and prostaglandin E2 for accelerating labour.

In a prospective study of 52 consecutive women who required acceleration of labour intravenous prostaglandin E2 (PGE2) was used as the oxytocic agent. These mothers were matched for age, parity, height, gestational age, initial cervical dilatation, and station and position of the fetal head with 52 women whose labours were accelerated with oxytocin; both drugs were equally effective. Acceleration to delivery intervals, second-stage durations, the number of assisted deliveries, and Apgar scores were similar regardless of the oxytocic used. Although PGE2 compares well with oxytocin, it offers no further advantages and is more expensive and less well tried than oxytocin.     

Comparison of natural and synthetic prostaglandin E2 tablets in labour induction.

A multicentre, randomized, double-blind trial compared the efficacy and safety of and tolerance to natural and synthetically produced prostaglandin E2 tablets in the induction of labour in 202 women. The compounds were similarly effective, inducing labour in approximately 66% of patients. The total dose required and the interval between induction and delivery were similar in the two groups, as were the Apgar scores at 1 and 5 minutes and the incidence of maternal and fetal side effects.     

Pathogenesis of neonatal hyperbilirubinaemia after induction of labour with oxytocin.

To determine the pathogenesis of neonatal hyperbilirubinaemia after oxytocin-induced labour venous cord blood from 95 healthy newborn infants was examined. Of these, 15 were delivered by elective caesarean section, 40 after spontaneous labour, and 40 after oxytocin-induced labour. There was no significant difference in any haematological or biochemical variable between the first two groups. Infants born after oxytocin-induced labour, however, showed clear evidence of increased haemolysis associated with significantly decreased erythrocyte deformability (P less than 0.001). In-vitro studies showed a time- and dose-related reduction in erythrocyte deformability in response to oxytocin. The findings suggest that the vasopressin-like action of oxytocin causes osmotic swelling of erythrocytes leading to decreased deformability and hence more rapid destruction with resultant hyperbilirubinaemia in the neonate.     

Uterine priming with oral prostaglandin E2 prior to elective induction with oxytocin.

Fifty pregnant women at term, with a cervix unfavorable for induction, were electively induced with intravenous oxytocin after priming with either oral prostaglandin E2 or a placebo. Oral PGE2 was effective in increasing the Bishop score and in inducing labor prior to the induction, but did not increase the incidence of successful inductions.     

Prostaglandin release from preparations used vaginally for the induction of labour

The release and absorption profiles from the vagina of PGE2 in different vehicles used for cervical ripening and labour induction have been studied observing changes in concentrations of PGE metabolite (PGEM) and PGF metabolite (PGFM). In all groups a rise in PGEM concentration occurred over the 6 hour observation time but with wide variation. The profiles obtained differed markedly between the preparations under investigation correlating with the uterine contractions generated. PGFM generally showed little change. The model used could be explored further to enable modification of the vehicles used for PGE2 incorporation to achieve improved clinical results.     

Inducing labour with vaginally administered prostaglandin E2.

In 50 consecutive pregnant women at a 125-bed community hospital with 1000 deliveries annually, labour was induced with prostaglandin E2 administered intravaginally. There were no stillbirths or neonatal deaths, and complications in the mothers were few. In nine women (18%) oxytocin was subsequently administered because of a failure of labour to progress; in spite of this, cesarean section was required in two (4%) of the patients. The overall cesarean section rate was 6%. Prostaglandins have been used routinely to induce labour in the United Kingdom for several years. This noninvasive method is safe, effective and well received by women in a community hospital setting, including those wanting "natural childbirth".     

The induction of labour by the intravenous infusion of prostaglandin F2alpha

Labour was induced by the intravenous infusion of prostaglandin F2alpha in 106 patients at 36-44 weeks of pregnancy. The induction was successful in 80% of the women. The total dose needed ranged from 0.1 to 14.2 mg of PGF2alpha. The uterine activity and fetal heart rate were recorded by cardiotocography. The contraction pattern and induction-delivery time were the same as reported for induction with oxytocin. In one case uterine hyperactivity occurred after rupture of the membranes. No serious adverse effects were seen, but in a few cases local irritation was noted at the site of infusion. The condition of the infants was generally good. It might be concluded that PGF2alpha seems valuable for the induction of labour, but due to the risk for over-stimulation careful supervision is needed.     

Prostaglandin E2 induction of monoblastic differentiation utilizes both cAMP and non-cAMP dependent signalling systems.

U937 cells can be induced to express receptor for complement 5a (C5aR) by sequential 2 day treatments of cells with dihydroxyvitamin D-3 (1,25(OH)2D3) followed by prostaglandin E2. We asked whether the action of prostaglandin E2 to cause maximal C5aR expression required only activation of the cAMP-dependent protein kinase (PKA). Prostaglandin E2 dose dependently activated PKA in control and 1,25(OH)2D3 treated cells; by 4 h the PKA did not respond to further prostaglandin E2 challenge. We hypothesized that prostaglandin E2 actions transduced via PKA should be complete by 4 h; i.e., C5aR induction should be equivalent in cells treated with prostaglandin E2 for 4 h and for 2 days. All cells were treated for the first 2 days with 1,25(OH)2D3 and the second 2 days with prostaglandin E2 or cAMP analogs. C5aR number was measured after 4 days total culture. 4 h pulse treatments with agents were given at the end of the 1,25(OH)2D3 treatment. Cells exposed to a 4 h pulse of prostaglandin E2 had only 68.2 +/- 4.4% the amount of C5aR seen in cells continuously exposed to prostaglandin E2. Continuous culture with a cAMP analog pair (50 microM each of 8-thiomethyl-cAMP + N6-benzoyl-cAMP), which caused a 41.7% +/- 10.8% increase PKA activation above basal, resulted in only 51% +/- 16% of the C5aR numbers seen in cells cultured for 2 days with prostaglandin E2, where PKA remained at basal activity. We therefore concluded that C5aR expression caused by prostaglandin E2 could not be ascribed entirely to duration or degree of activation of cAMP-dependent signalling pathways. We investigated the possibility that the calcium sensitive protein kinase C was involved. Cytoplasmic protein kinase C was increased 154% +/- 14% above control in cells treated with sequential 2 days treatments of 1,25(OH)2D3 and prostaglandin E2. A 147% +/- 2% increase in membrane associated protein kinase C was also seen 10 min after phorbol myristate acetate stimulation in the above treatment group. Finally, phorbol myristate acetate augmented the C5aR induction caused by cAMP analog. We propose that the mechanism of prostaglandin E2 synergism with 1,25(OH)2D3 in causing C5aR induction in U937 cells includes signal transduction not only by the cAMP cascade, but also via protein kinase C modulated pathways.     

Prostaglandin E2 localization in the rat ileum.

Summary The application of anti-prostaglandin E₂ immunoglobulin to plastic-embedded thin sections of the rat ileum has permitted the localization of prostaglandin E₂ in this tissue. In agreement with the published data (Chock & Schmauder-Chock (1988), Schmauder-Chock & Chock (1989)), the results also suggest the presence of an arachidonic acid cascade in the granules of various secretory cells of the gut. Since antibody labelling was found within the secretory granules of connective tissue mast cells, goblet cells, and Paneth cells, the presence of the arachidonic acid cascade in these granules is implied. The appearance of prostaglandin E₂ over the non-cellular internal elastic lamina of arterioles suggests that it may have been secreted along with the elastin. The even distribution of prostaglandin throughout the cytoplasm of the erythrocyte is consistent with the concept that this cell scavenges the eicosanoid from the circulation. These data further link the secretorh granule to the production of eicosanoids and therefore illustrate the potential sources of prostaglandins in the rat ileum.     

Prostaglandin E2-dependent induction of B cell unresponsiveness. Role of surface Ig and Fc receptors

Previously, we demonstrated that two signals were required for accessory cells to induce B cell unresponsiveness: tolerogenic Ig and PG. The purpose of this study was to investigate whether PGE2, in an accessory cellfree system, promoted fluorescein-specific B cell unresponsiveness in conjunction with ligands which bound to surface Ig (sIg) and/or FcR. Several conditions were found whereby PGE2 was obligatory for unresponsiveness. In the presence of aggregated, but not monomeric non-Ig fluorescein-Ag, direct plaque-forming cell responses were reduced by 60%. In contrast, engagement of the B cell FcR by aggregated IgG2b or by the 2.4G2 anti-FcR mAb failed to induce unresponsiveness, even when PGE2 was present. These data suggested that PGE2 could promote sIg-mediated negative signaling. A second condition where PGE2 promoted unresponsiveness occurred when sIg and FcR were simultaneously engaged by monomeric ligands. However, when sIg and FcR were cross-linked, PGE2-independent B cell unresponsiveness occurred. Interestingly, when subinhibitory doses of cross-linking agents were used, PGE2 dependent negative signaling resulted. PGE2 can thereby promote B cell unresponsiveness in three different situations. First, when sIg is extensively cross-linked by aggregated antigens or those with repeating determinants. Second, when sIg is engaged by monomeric antigen and when the B cell FcR is also occupied. Third, under conditions where B cell sIg and FcR are inadequately cross-linked. These situations can occur in vivo when macrophages in the B cell microenvironment (i.e., follicles) secrete PGE2 and when Ag with repeating epitopes, or immune complexes capable of binding B cell sIg and FcR are present. Thus, PGE2 can serve as an important regulatory element in limiting antibody formation.     

Selective induction of labour.

In a prospective study of 1000 consecutive primigravidae labour was induced on 95 occasions. None of 16 perinatal deaths and none of 4 cases of suspected brain damage occurred after prolonged pregnancy or pre-eclampsia. It is concluded that a low incidence of induction is compatible with good results and that enthusiasm for the statistical concept of high risk in obstetric practice should be reviewed in the interest of mothers and children as individuals.     

Prostaglandin endoperoxides 21. Covalent binding of levuglandin E2 with proteins

Levuglandin E2 (LGE2), a gamma-ketoaldehyde produced by rearrangement of the prostaglandin endoperoxide PGH2 under the aqueous conditions of its biosynthesis, binds covalently with ram seminal vesicle microsomes. Totally synthetic 5,6-ditritio-LGE2 was prepared and used to determine that rapid covalent binding of LGE2 (initially 800 microM) occurs with 6.4 microM bovine serum albumin (greater than 10 equiv within 1 min) which approaches saturation (approximately 16 equiv) after 40 min at 37 degrees C.     

Induction of labour with a sustained-release prostaglandin E2 vaginal pessary.

A new polymer vaginal pessary providing sustained constant release of prostaglandin E2 was administered to 66 patients before planned induction of labour. Effective ripening of the unfavourable cervix was achieved in each of 18 primigravidas, in eight of whom labour was initiated without further treatment. When the cervix was moderately favourable the need for orthodox induction of labour was obviated in 16 out of 23 primigravidas and 21 out of 23 multigravidas. This method of sustained release of prostaglandin E2 is simple and convenient and readily acceptable to the patient; it is an important step in the development of non-invasive methods of inducing labour.     

The induction of labour by the intravenous infusion of prostaglandin F2α

labour was induced by the intravenous infusion of prostaglandin F_2α in 106 patients at 36–44 weeks of pregnancy. The induction was successful in 80% of the women. The total dose needed ranged from 0.1 to 14.2 mg of PGF_2α. The uterine activity and fetal heart rate were recorded by cardiotocography. The contraction pattern and induction-delivery time were the same as reported for induction with oxytocin. In one case uterine hyperactivity occurred after rupture of the membranes. No serious adverse effects were seen, but in a few cases local irritation was noted at the site of infusion. The condition of the infants was generally good.It might be concluded that PGF_2α seems valuable for the induction of labour, but due to the risk for overstimulation careful supervision is needed.