Platelet-derived growth factor elicits cyclic AMP accumulation in Swiss 3T3 cells: role of prostaglandin production

Partially purified porcine PDGF or purified human PDGF in the presence of phosphodiesterase inhibitors caused marked accumulation of cAMP in Swiss 3T3 cells. The responses were time- and dose-dependent; half-maximal effect was obtained at 0.6 nM PDGF. Indomethacin prevented the increase of cAMP levels in a dose-dependent manner; half-maximal effect was obtained at about 10 nM. Addition of PDGF increased (at least 25-fold) the production of E-type prostaglandins; PGE reached a concentration in the medium of 26 ng/ml 1 hr after treatment with human PDGF. This concentration of PGE produced a similar level of cAMP to that found with PDGF, suggesting that the PDGF-induced increase in cAMP is mediated by E-type prostaglandins released in the culture medium. Increased cAMP levels promoted by PDGF acting through stimulation of E-type prostaglandin synthesis may contribute to signal the initiation of cell proliferation in 3T3 cells.     

Prostaglandin-induced abortion and outcome of subsequent pregnancies: a prospective controlled study

We analysed a prospective series of 204 pregnancies occurring in 168 women after a prostaglandin-induced abortion. The mean (±standard error of mean) interval between abortion and first subsequent conception was 10·4 ± 0·6 months; no patient reported secondary subfertility.Fifty-five of the subsequent pregnancies were terminated, 23 during the second trimester, again using prostaglandins. Of the 149 pregnancies not terminated, 127 were delivered at term, and 19 spontaneously aborted, seven during the second trimester; there was one missed abortion and two ectopic pregnancies. Morbidity in the 127 term pregnancies was infrequent; spontaneous preterm labour occurred in three patients, and four singleton infants weighed less than 2500 g at birth. There was no apparent association between morbidity in the subsequent pregnancies and the period of gestation at the time of the previous abortion, route of prostaglandin administration, or need for post-abortion curettage.The results obtained overall were very similar to a control group of 612 women consecutively admitted for delivery or abortion to the Oxford obstetrical and gynaecological units. There was, however, an increased incidence of spontaneous abortion and placenta praevia after prostaglandin-induced abortion, and the multigravidae in that group had a longer average duration of labour than the control group. Sixty-five per cent of the post-abortion pregnancies were unplanned compared with 36% of the control group.     

On the mechanism of action of 15-methyl-PGF2 alpha as an abortifacient.

Several hours following administration of long acting vaginal suppositories containing 3.0 mg of 15-methyl-PGF2 alpha for interruption of second trimester pregnancies there is an up to 10-fold increase in endogenous production of PGE2 and PGF2 alpha before abortion as reflected by gas chromatographic-mass spectrometric determination of the major plasma metabolites of PGE2 and PGF2 alpha. The data suggest that this increased formation of endogenous prostaglandins contributes to the induced uterine activity during the latter part of the abortion process.     

On the mechanism of action of 15-methyl-PGF2α as an abortifacient

Several hours following administration of long acting vaginal suppositories containing 3.0 mg of 15-methyl-PGF_2α for interruption of second trimester pregnancies there is an up to 10-fold increase in endogenous production of PGE₂ and PGF_2α before abortion as reflected by gas chromatographic-mass spectrometric determination of the major plasma metabolites of PGE₂ and PGF_2α. The data suggest that this increased formation of endogenous prostaglandins contributes to the induced uterine activity during the latter part of the abortion process.     

Vaginally administered 16,16-dimethyl-PGE2 for the induction of midtrimester abortion

Thirty patients in the 13th–20th week of gestation underwent therapeutic abortion utilizing vaginally administered 16,16-dimethyl-PGE₂ (free acid) suppositories. The first 15 patients obtained individual doses in the range of 400–1200 μg given every three hours (mean total dose 4.2 mg). In the following 15 patients a fixed dose schedule was used (800 μg followed by 1000 μg every three hours; mean total dose 5.3 mg). All but one of the 30 patients aborted. The mean induction-abortion interval for all patients was 16.8±6.9 hours (mean ± S.D.) With the fixed dose regime the success rate was 100% and the induction-abortion interval 16.0±5.9 hours. Because gastro-intestinal side effects were minimal, neither anti-emetic nor anti-diarrheic medication was required. A slight elevation of temperature was noted in five patients. The uterine response to the vaginal administration of this compound was characterized by a gradual increase in uterine tonus followed by sustained stimulation. The results are interpreted to suggest that the vaginal administration of 16,16-dimethyl-PGE₂ is a useful alternate method for the induction of second trimester abortion. Moreover, this compound seems to cause fewer gastro-intestinal side effects than other prostaglandins administered by the vaginal route at our department.     

Prostaglandin synthesis in rabbit graafian follicles in vitro. Effect of luteinizing hormone and cyclic AMP

We have demonstrated the capacity of isolated follicles from estrous rabbits to synthesize prostaglandins in vitro and to respond to gonadotropins added to the incubation medium with an increased accumulation of these lipids. The increase in both prostaglandins became apparent only after 5 hours of incubation. The effect was specific for hormones with LH activity and the threshold dose of LH appeared to be 0.005 μg/ml. In addition, we have shown that cyclic AMP (0.02 M) added to the incubation medium also increased prostaglandin in this in vitro system and appears to be a likely mediator of this action of LH.     

Prostaglandin synthesis by isolated cells of rat uterus: production rates, and effects of indomethacin and histamine

Luminal epithelial and residual cells (mainly of the endometrial stromal tissue) of proestrous rat uteri have been isolated and cultured in defined medium. The prostaglandins produced during a short-term incubation (2 h) in the presence of 10 microM arachidonic acid (to optimize PG production) were determined by direct assay of the culture medium. For the epithelial cells, PGF2 alpha was produced in greatest amounts, followed by 6-keto PGF1 alpha and PGE, while low levels were synthesized by the residual cells. The synthesis of PGF2 alpha by the epithelial cells was inhibited by incorporating indomethacin into the medium and an IC50 value of 2.3 microM was obtained. Incubations performed with histamine in the absence of exogenous arachidonic acid indicated that the pathways for the production of individual prostaglandins were followed to different relative extents, with the production of 6-keto PGF1 alpha being enhanced for both groups of cells when compared to incubations with arachidonic acid.     

Factors associated with immediate abortion complications.

OBJECTIVE: To identify factors associated with increased risk of immediate complications from induced abortion. DESIGN: Retrospective analysis of a provincial database. SETTING: All Ontario general hospitals in which abortions are performed and all free-standing abortion clinics in Ontario. POPULATION: Women in Ontario aged 15 to 44 years who underwent an induced abortion in the province (without concurrent sterilization) between Jan. 1, 1992, and Dec. 31, 1993. OUTCOME MEASURES: Recording of complications at the time of the procedure, gestational age, type of procedure, place of abortion (hospital or clinic), and patient''s age, parity and history of previous abortion (spontaneous or induced). RESULTS: During the study period 83 469 abortions were performed that met our inclusion criteria. Immediate complications were reported in 571 cases (0.7%). Multivariate logistic regression analysis revealed that, after other variables were controlled for, the patient''s age, parity and history of previous abortions (spontaneous or induced) were not significant risk factors for immediate complications; however, gestational age, method of abortion and place of abortion were significant risk factors (p < 0.001). The odds ratio (OR) for having a complication from abortion was 1.3 (95% confidence interval [CI] 1.02 to 1.63) between 9 and 12 weeks, compared with having one after abortion at 9 weeks or earlier, and increased to 3.3 (95% CI 2.23 to 5.00) after abortion between 17 and 20 weeks. Compared with surgical dilatation and curettage (D&C), instillation of saline and instillation of prostaglandins were more likely to be associated with immediate complications (OR 24.0, 95% CI 13.22 to 43.70, and OR 11.7, 95% CI 6.43 to 21.18, respectively), whereas both suction D&C and insertion of a laminaria tent were less likely to be associated with immediate complications (OR 0.4, 95% CI 0.26 to 0.67, and OR 0.3, 95% CI 0.19 to 0.52, respectively). Compared with women who had an abortion in a free-standing clinic, the risk for immediate complications was greater among those who had an abortion in a hospital, especially a teaching hospital (OR 1.9, 95% CI 1.38 to 2.58), a nonteaching hospital with 200 to 399 acute care beds (OR 3.1, 95% CI 2.27 to 4.21) and a nonteaching hospital with fewer than 200 acute care beds (OR 5.9, 95% CI 4.04 to 8.64). CONCLUSION: The risk of immediate complications from induced abortion is very low. Unlike in previous studies, the woman''s age, parity and history of previous spontaneous or induced abortions were not found to be risk factors. However, advancing gestational age and procedures involving instillation of saline or prostaglandins were predictive factors of immediate complications.     

Alpha-fetoprotein in Abortion

The clinical value of maternal serum alpha-fetoprotein (AFP) as a guide to the outcome of threatened abortion was assessed. After the thirteenth week of gestation, abortion occurred more frequently (10/12) in women with abnormal serum AFP levels than in those (2/12) whose AFP concentrations were within the normal range. Low levels were present in women with blighted ovum and high concentrations were associated with intrauterine fetal death. In legal first and second trimester abortions, the circulating maternal AFP levels in postabortion samples were often higher than before abortion, irrespective of whether abortion was performed instrumentally or induced with prostaglandins. Maternal serum AFP levels provide a new means for prediction of the outcome of threatened abortion.     

Prostaglandin biosynthesis by lapine articular chondrocytes in culture

Secondary monolayer and spinner cultures of rabbit articular chondrocytes released into the culture medium prostaglandins the synthesis of which was inhibited by sodium meclofenamate. The prostaglandins measured by radioimmunoassay were, in order of decreasing abundance, prostaglandin E₂, 6-oxoprostaglandin F_1α, (the stable metabolite of prostacyclin) and prostaglandin F_2α. Several lines of evidence indicated that chondrocytes synthesize little if any thromboxane B₂ (the stable metabolite of thromboxane A₂). The presence of prostaglandins was confirmed by radiometric thin-layer chromatography of extracts of culture media incubated with [³H]arachidonic acid-labeled cells. In monolayer culture, chondrocytes synthesized immunoreactive prostaglandins in serum-free as well as serum-containing medium. Monolayer chondrocytes produced higher levels of prostaglandin E₂ relative to 6-oxo-prostaglandin F_1α than did spinner cells, but the latter synthesized more total prostaglandins. The identity of endogenous prostaglandins as well as those synthesized in short-term culture by rabbit cartilage slices was compared to those produced by chondrocytes in long-term culture. Chondrocytes synthesized all of the prosta-glandins found in articular cartilage. Minimal quantities of thromboxane B₂ were detected in cartilage. A higher percentage of 6-oxo-prostaglandin F_1α relative to other prostaglandins was found in cartilage than in either monolayer or spinner chondrocyte cultures. These results demonstrate that articular chondrocytes synthesize prostaglandins and prostacyclin. These prostaglandins may exert significant physiological effects on cartilage, since exogenous prosta-glandins depress chondrocyte sulfated-proteoglycan synthesis and may even promote proteoglycan degradation.     

Application of embryo rescue after interspecific crosses in the genus Rhododendron

Interspecific hybridization between evergreen pot azalea (Tsutsusi) cultivars and genotypes of other Rhododendron subgenera or sections (Rhododendron, Hymenanthes, Pentanthera, Vireya) is significantly hampered by many prezygotic and postzygotic barriers. The objective of our work was to overcome spontaneous abortion and lack of endosperm formation and to increase germination rates by establishing an embryo rescue protocol. The optimal germination medium for immature Rhododendron seeds was a basal medium supplemented with 145 μM GA₃. This medium induced germination of fertilized ovules after several sexual combinations of subgenera. Its use was clearly more efficient than in vivo sowing. The direction of the cross significantly influenced the occurrence of abortion, germination and albinism. The obtained seedlings were multiplied on Woody Plant Medium + 4.5 μM 2iP, and rooted afterwards. Finally, about 9% of the germinated ovules resulted in vigorously growing seedlings that were successfully acclimatized.     

Prostaglandins and post-abortion luteolysis in early pregnancy.

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF2alpha(15-me-PGF2alpha) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400mug 15-me-PGF2alpha extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly duriing the same period. Under the experimental conditions of this study neither 15-me-PGF2alpha nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Prostaglandin production by dispersed granulosa and theca interna cells from porcine preovulatory follicles

Prepubertal gilts were treated with 750 IU pregnant mares' serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Dispersed granulosa (GC) and theca interna (TIC) cells were prepared by microdissection and enzymatic digestion from follicles obtained 36, 72 and 108 h after PMSG treatment and incubated for up to 6 h in a chemically defined medium in the presence or absence of arachidonic acid, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and indomethacin. Production of prostaglandin E2 (PGE) and prostaglandin F2 alpha (PGF) was measured by radioimmunoassay. Both GC and TIC had the capacity to produce prostaglandins, with production by each cell type increasing markedly with follicular maturation. PGE was the major prostaglandin produced by both cellular compartments. Only PGE production by GC was consistently enhanced by addition of arachidonic acid to the incubation medium. Neither cell type was responsive to FSH and LH in vitro. Indomethacin inhibited the production of PGE and PGF by both cell types. These results provide convincing evidence for an intrafollicular source of prostaglandins and indicate that both cellular compartments contribute significantly to the increased production of prostaglandins associated with follicular rupture.     

Patterns of prostaglandin production in the bovine fetal and maternal vasculature

Prostaglandin (PG) synthesis by the blood vessel wall may contribute to the regulation of vascular tone and prevent deposition of platelets. The pattern of prostaglandin synthesis was investigated in vascular tissues from fetal, maternal and non-pregnant cows. Thin slices of blood vessels were incubated in Krebs' solution to which was added [1-¹⁴C] arachidonic acid. The radioactive products were extracted from the incubation medium, separated by thin-layer chromatography, and quantitated by scintillation counting. In all blood vessels studied the principal prostaglandin recovered from the incubation medium was 6 keto-PGF_1α, the stable hydrolysis product of prostacyclin; the highest yield of radioactive prostaglandins was obtained with fetal tissues. Only the mesenteric arteries obtained from pregnant and non-pregnant cows demonstrated a biosynthetic capacity comparable to those of the fetal vasculature; pulmonary arteries and aortas of adult animals had a much lower capacity to synthesize prostaglandins. Release of prostaglandins by the ductus arteriosus was also measured by mass fragmentography. Again 6 keto-PGF_1α was the predominant product: 6 keto-PGF_1α = 223 versusPGE₂ = 10 and PGF_2α = 15 ng/g of wet weight of tissue. The identity of 6 keto-PGF_1α was confirmed by mass spectroscopy. The high capacity of fetal blood vessels to synthesize PGI₂ may reflect an important role for this substance in the regulation of the fetal circulation.     

Hormonal control of glycogenolysis in parenchymal liver cells by Kupffer and endothelial liver cells

Conditioned media of isolated Kupffer and endothelial liver cells were added to incubations of parenchymal liver cells, in order to test whether secretory products of Kupffer and endothelial liver cells could influence parenchymal liver cell metabolism. With Kupffer cell medium an average stimulation of glucose production by parenchymal liver cells of 140% was obtained, while endothelial liver cell medium stimulated with an average of 127%. The separation of the secretory products of Kupffer and endothelial liver cells in a low and a high molecular weight fraction indicated that the active factor(s) had a low molecular weight. Media, obtained from aspirin-pretreated Kupffer and endothelial liver cells, had no effect on the glucose production by parenchymal liver cells. Because aspirin blocks prostaglandin synthesis, it was tested if prostaglandins could be responsible for the effect of media on parenchymal liver cells. It was found that prostaglandin (PG) E1, E2, and D2 all stimulated the glucose production by parenchymal liver cells, PGD2 being the most potent. Kupffer and endothelial liver cell media as well as prostaglandins E1, E2, and D2 stimulated the activity of phosphorylase, the regulatory enzyme in glycogenolysis. The data indicate that prostaglandins, present in media from Kupffer and endothelial liver cells, may stimulate glycogenolysis in parenchymal liver cells. This implies that products of Kupffer and endothelial liver cells may play a role in the regulation of glucose homeostasis by the liver.     

Single extra-amniotic injection of prostaglandin E2 in viscous gel to induce mid-trimester abortion.

In a preliminary study a single extra-amniotic injection of 1.5 mg of prostaglandin E-2 incorporated into an aqueous viscous gel was given to 24 patients aborted within 24 hours, and the mean induction-abortion interval (plus or minus S.E. of mean) was 13.5 plus or minus 1.5 hours. Vomiting occurred in seven patients, and transient severe uterine cramps, pallor, nausea, and shivering occurred in one patient immediately after injection. Complete abortion occurred in 20patients. A delay in the time taken to abort seemed to be associated with an immediate and rapid rise in uterine tone after the injection which required prompt analgesia; this probably reflected rapid decidual absorption and dissolution of the prostaglandins away from their site of action. The degree of distention of the catheter-retaining balloon did not influence abortion times.     

Prostaglandins and post-abortion luteolysis in early pregnancy

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF_2α (15-me-PGF_2α) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400μg 15-me-PGF_2α extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly during the same period. Under the experimental conditions of this study, neither 15-me-PGF_2α nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Induction of Abortion by Extra-amniotic Administration of Prostaglandins E2 and F2 α

The use of prostaglandins E₂ and F₂α, administered by extra-amniotic instillation, for the induction of abortion was studied in 94 patients in the first and second trimesters of pregnancy. Abortion was successfully induced in 87% of patients within 36 hours and in 94% within 48 hours. The mean abortion time was 22·4 hours. In 60% of patients abortion was complete.Though the differences were not statistically significant, on average multigravid patients aborted more quickly than primigravidae, while the mean abortion time in PGE₂-treated patients was less than in those receiving PGF₂α.No serious complications occurred. Some side effects were observed. Occasional vomiting was the commonest symptom but the incidence of side effects was lower than with alternative routes of administration. A leucocytosis was often noted but there were no significant instances of infection.The method has proved a safe and effective means of terminating pregnancies in the second trimester.     

Prostaglandins and post-abortion luteolysis in early pregnancy

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF₂ (15-me-PGF₂) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400g 15-me-PGF₂ extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly during the same period. Under the experimental conditions of this study, neither 15-me-PGF₂ nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Prostaglandin F2α Metabolite Levels Following an Embryo Transfer Procedure in the Mare

Hormonal, chemical, and mechanical stimuli can activate the arachidonic acid cascade and result in formation of prostaglandins and related substances. These compounds can have a profound role in the initiation of the inflammatory process (Higgins & Lees 1984). Prostaglandin (PG) F2α is the key hormone in reproductive physiology with well-known effects on reproductive performance e.g. luteolysis and abortion. An activation of the arachidonic acid cascade, caused by mechanical manipulation during an embryo transfer procedure, might be one explanation for early embryonic loss.