Simulation and risk assessment of typical antibiotics in the multi-media environment of the Yangtze River Estuary under tidal effect.

Frequent human activities in estuary areas lead to the release of a large number of antibiotics, which poses a great threat to human health. However, there are very limited studies about the influence of the special natural phenomena on the occurrence and migration of antibiotics in the environment. In this study, we simulated the migration and transformation of six typical antibiotics, including oxytetracycline (OTC), tetracycline (TC), norfloxacin (NOR), ofloxacin (OFX), erythromycin (ETM), and amoxicillin (AMOX), in the environmental media from 2011 to 2019 in the Yangtze River Estuary, by using the level III multi-media fugacity model combined with the factor of tides. The simulation results showed that the most antibiotics mainly existed in soil and sediment while erythromycin were found mainly in water. The concentrations of antibiotics in air, freshwater, seawater, groundwater, sediment, and soil were 10-23-10-25, 0.1-12 ng/L, 0.02-7 ng/L, 0.02-16 ng/L, 0.1-13 ng/g, and 0.1-15 ng/g respectively. Sensitivity analysis showed that the degradation rate (Km) and the soil-to-water runoff coefficient (Kl) were important model parameters, indicating that hydrodynamic conditions had a significant impact on the migration of antibiotics in various environmental phases in estuarine areas. Tide can enhance the exchange between water bodies and cause the transformation of the antibiotics from freshwater to seawater and groundwater, which improved the accuracy of the model, especially the seawater and soil phase. Risk assessments showed that amoxicillin, erythromycin, ofloxacin, and norfloxacin posed a threat to the estuarine environment, but the current source of drinking water did not affect human health. Our findings suggested that, when one would like to exam the occurrence and migration of antibiotics in environment, more consideration should be given to the natural phenomena, in addition to human activities and the nature of antibiotics.

Comparison of external calibration and isotope dilution LC-ICP-MS/MS for quantitation of oxytocin and its selenium analogue in human plasma.

In the present study, a method for quantitation of the pharmaceutical peptide oxytocin (OT) and its diselenide-containing analogue (SeOT) in human plasma was developed using gradient elution LC-ICP-MS/MS. Plasma samples were precipitated with acetonitrile containing 1.0% TFA in a volume ratio of 1+3 (sample+precipitation agent) before analysis. Post-column isotope dilution analysis (IDA) was applied for quantitation and was compared with external calibration. Both calibration methods appeared to be fit for purpose regarding figures of merit including linearity, precision, LOD, LOQ and recovery. Analysis of OT and SeOT showed that selenium-based analysis is considerably more sensitive and selective compared to the sulfur-based analysis. Despite the relatively simpler setup of external calibration, IDA can be advantageous because it compensates for instrument drift and changes in organic solvent concentration. The method was applied for a stability study showing the degradation of OT and SeOT in plasma. The degradation of SeOT was faster than the degradation of OT in plasma. Thus, possible stability effects should be considered before replacing a disulfide bridge with a diselenide bridge or introducing a diselenide label in a potential drug.

Quality of oxytocin and misoprostol in health facilities of Rwanda.

Sustainable Development Goal 3.1 calls for a reduction of the maternal mortality ratio to less than 70 per 100,000 live births by 2030. The most important cause of maternal mortality is post-partum haemorrhage (PPH). Oxytocin injections and misoprostol tablets are medicines of first choice for the management of PPH in low- and middle-income countries (LMICs). Unfortunately, both substances are chemically unstable, and previous studies have revealed serious quality problems of these medicines in LMICs. The present study is the first report on their quality in Rwanda. From 40 randomly selected health facilities (hospitals, health centers, retail pharmacies and private clinics) in different parts of Rwanda, as well as from six wholesalers and government stores, oxytocin injections and misoprostol tablets were collected. Oxytocin storage temperatures in the health facilities were monitored for six months using temperature data loggers, and found to correctly follow the storage requirements stated by the manufacturers (2-8°C, or room temperature) with few minor deviations. Oxytocin injections (57 samples, representing seven batches of four brands) were tested for their oxytocin content and pH value according to the United States Pharmacopeia. Twenty-four samples from three European manufacturers passed all tests. However, all nine samples of one batch of a Chinese manufacturer showed an excessive content of oxytocin (range 117.2-121.5% of the declared amount). Another batch of the same manufacturer showed extreme variations of the concentration of the preservative benzyl alcohol. Misoprostol tablets (25 samples, representing ten batches of six brands) were tested for content and dissolution according to the International Pharmacopoeia. Fifteen samples passed, but all 10 samples of two brands from India failed with extreme deviations, containing only 42.5-48.7% of the stated amount of misoprostol. In conclusion, oxytocin quality in Rwanda was better than reported from other African countries. However, two extremely substandard brands of misoprostol tablets were found. The Rwandan authorities reacted quickly and efficiently, and recalled these substandard medicines from the market. For oxytocin and misoprostol, with their well-known problems of quality and stability, procurement should possibly be restricted to medicines which are WHO-prequalified or which have been manufactured in countries with stringent regulatory authorities.

Quality, availability and storage conditions of oxytocin and misoprostol in Malawi.

BACKGROUND: Postpartum haemorrhage (PPH) is the leading cause of maternal mortality in low- and middle-income countries (LMICs). Oxytocin and misoprostol are used for the prevention and treatment of PPH. However, both medicines are chemically unstable and sensitive to environmental conditions. Previous studies reported a high prevalence of substandard oxytocin and misoprostol preparations in LMICs. METHODS: In randomly selected health facilities of four districts of Malawi, the availability of oxytocin and misoprostol was determined, and the knowledge of health workers on storage requirements and use of oxytocics was assessed. Temperature loggers were used to record the storage temperature of oxytocics. Samples of oxytocin injections and misoprostol tablets were collected from the health facilities and from wholesalers. Oxytocin samples were analysed for identity, assay (= quantity of oxytocin) and for pH value according to United States Pharmacopeia 40. Misoprostol samples were analysed for identity, assay, dissolution and related substances according to the International Pharmacopeia 2017. RESULTS: All visited hospitals and health centers had oxytocin available. At non-refrigerated storage sites, the recorded mean kinetic temperature exceeded the oxytocic's storage temperature stated on the labels in 42% of the sites. At refrigerated storage sites, the required temperature of 2-8 °C was exceeded in 33% of the sites. Out of 65 oxytocin samples, 7 (11%) showed moderate deviations from specification, containing 82.2-86.8% of the declared amount of oxytocin. Out of 30 misoprostol samples, 5 (17%) showed extreme deviations, containing only 12.7-30.2% of the declared amount. The extremely substandard misoprostol was reported to the national authorities and to WHO, leading to an immediate recall of the respective brand in Malawi. The UK-based distributor of this brand closed its business shortly thereafter. CONCLUSION: Availability of oxytocin was excellent in Malawi, and its quality was better than reported in previous studies in other LMICs. However, storage conditions at the health facilities often did not meet the requirements. Extremely substandard misoprostol tablets were found, representing a serious risk to maternal health. This shows the need for continued efforts for quality assurance in medicine procurement and registration, as well as for post-marketing surveillance.

Stability of oxytocin along the supply chain: A WHO observational study.

Postpartum haemorrhage is the leading cause of maternal mortality in low-income countries and oxytocin is the drug recommended by WHO for preventing and treating it. There are concerns about the quality of oxytocin available at the service level provider. The study aimed to document how temperature variations along the supply chain affect quality of oxytocin. The study was run from March to June 2015 in four regions of Ghana. 130 ampoules of oxytocin were shipped from the manufacturer to service level following Ghanaian public sector supply chain. Along the supply chain, temperatures were recorded continuously. After one month storage at central, regional and service level, ampoules were sent to laboratory for testing. Quality of the initial oxytocin sample from the manufacturer and the 130 oxytocin samples received from study points were tested according to International Pharmacopeia monograph. Samples fully complied with specifications. Temperature profile showed that the lowest and highest temperatures experienced were -9.9 °C and +30.1 °C. The results of this study indicate that the activity of oxytocin was not affected by these temperature excursions which occurred along the supply chain. The quality of the oxytocin from the manufacturer as well as from the service level was within the required specifications.

In vivo and in vitro anti-inflammatory activity of Cryptostegia grandiflora Roxb. ex R. Br. leaves.

BACKGROUND: Despite Cryptostegia grandiflora Roxb. ex R. Br. (Apocynaceae) leaves are widely used in folk Caribbean Colombian medicine for their anti-inflammatory effects, there are no studies that support this traditional use. Therefore, this work aimed to evaluate the effect of the total extract and primary fractions obtained from Cryptostegia grandiflora leaves, using in vivo and in vitro models of inflammation, and further get new insights on the mechanisms involved in this activity. RESULTS: Ethanolic extract of Cryptostegia grandiflora leaves, and its corresponding ether and dichloromethane fractions, significantly reduced inflammation and myeloperoxidase activity (MPO) in ear tissue of mice treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Histological analysis revealed a reduction of edema and leukocyte infiltration. Complementarily, we demonstrated that extract and fractions reduced nitric oxide (NO•) and prostaglandin E2 (PGE2) production in LPS-stimulated RAW 264.7 macrophages, as well as scavenging activity on DPPH and ABTS radicals. CONCLUSIONS: Our results demonstrated for the first time the anti-inflammatory activity of Cryptostegia grandiflora leaves, supporting its traditional use. This activity was related to inhibition of MPO activity, and PGE2 and NO• production. These mechanisms and its antioxidant activity could contribute, at least in part, to the anti-inflammatory effect showed by this plant.

In vivo and in vitro anti-inflammatory activity of Cryptostegia grandiflora Roxb. ex R. Br. leaves

BACKGROUND: Despite Cryptostegia grandiflora Roxb. ex R. Br. (Apocynaceae) leaves are widely used in folk Caribbean Colombian medicine for their anti-inflammatory effects, there are no studies that support this traditional use. Therefore, this work aimed to evaluate the effect of the total extract and primary fractions obtained from Cryptostegia grandiflora leaves, using in vivo and in vitromodels of inflammation, and further get new insights on the mechanisms involved in this activity. RESULTS: Ethanolic extract of Cryptostegia grandiflora leaves, and its corresponding ether and dichloromethane fractions, significantly reduced inflammation and myeloperoxidase activity (MPO) in ear tissue of mice treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Histological analysis revealed a reduction of edema and leukocyte infiltration. Complementarily, we demonstrated that extract and fractions reduced nitric oxide (NO•) and prostaglandin E2 (PGE2) production in LPS-stimulated RAW 264.7 macrophages, as well as scavenging activity on DPPH and ABTS radicals. CONCLUSIONS: Our results demonstrated for the first time the anti-inflammatory activity of Cryptostegia grandiflora leaves, supporting its traditional use. This activity was related to inhibition of MPO activity, and PGE2 and NO• production. These mechanisms and its antioxidant activity could contribute, at least in part, to the anti-inflammatory effect showed by this plant.

Oxytocic plant cyclotides as templates for peptide G protein-coupled receptor ligand design.

Cyclotides are plant peptides comprising a circular backbone and three conserved disulfide bonds that confer them with exceptional stability. They were originally discovered in Oldenlandia affinis based on their use in traditional African medicine to accelerate labor. Recently, cyclotides have been identified in numerous plant species of the coffee, violet, cucurbit, pea, potato, and grass families. Their unique structural topology, high stability, and tolerance to sequence variation make them promising templates for the development of peptide-based pharmaceuticals. However, the mechanisms underlying their biological activities remain largely unknown; specifically, a receptor for a native cyclotide has not been reported hitherto. Using bioactivity-guided fractionation of an herbal peptide extract known to indigenous healers as "kalata-kalata," the cyclotide kalata B7 was found to induce strong contractility on human uterine smooth muscle cells. Radioligand displacement and second messenger-based reporter assays confirmed the oxytocin and vasopressin V1a receptors, members of the G protein-coupled receptor family, as molecular targets for this cyclotide. Furthermore, we show that cyclotides can serve as templates for the design of selective G protein-coupled receptor ligands by generating an oxytocin-like peptide with nanomolar affinity. This nonapeptide elicited dose-dependent contractions on human myometrium. These observations provide a proof of concept for the development of cyclotide-based peptide ligands.

Monitoring of methylergometrine in human breast milk by solid-phase extraction and high-performance liquid chromatography with fluorimetric detection.

A high-performance liquid chromatographic assay has been developed for the detection and quantification of the conventional postnatal uterotonic drug, methylergometrine, in human breast milk using a C-18 reversed-phase column by isocratic elution. The analytical method consisted of sample clean-up by solid-phase extraction, and the fluorescence detection required only 8.5 min per sample for separation and quantitation. This assay gave intra- and inter-assay coefficients of variation of less than 7.9% and 7.7%, respectively, and the detection limit was approximately 50 pg/ml. This method was applied for drug level monitoring in the breast milk of patients given methylergometrine.

Complete NMR analysis of oxytocin in phosphate buffer.

Complete NMR analysis of oxytocin (OXT) in phosphate buffer was elucidated by one-dimensional (1D)- and two-dimensional (2D)-NMR techniques, which involve the assignment of peptide amide NH protons and carbamoyl NH(2) protons. The (1)H-(15)N correlation of seven amide NH protons and three carbamoyl NH(2) protons were also shown by HSQC NMR of OXT without (15)N enrichment.

Liquid chromatographic analysis of oxytocin and its related substances.

A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

Reduction of scar formation in full-thickness wounds with topical celecoxib treatment.

Adult wound repair occurs with an initial inflammatory response, reepithelialization, and the formation of a permanent scar. Although the inflammatory phase is often considered a necessity for successful adult wound healing, fetal healing studies have shown the ability to regenerate skin and to heal wounds in a scarless manner in the absence of inflammation. The cyclooxygenase-2 (COX-2) enzyme, a known mediator of inflammation, has been shown to contribute to a variety of inflammatory conditions and to the development of cancer in many organs. To examine the role of COX-2 in the wound healing process, incisional wounds were treated topically with the anti-inflammatory COX-2 inhibitor celecoxib. Acutely, celecoxib inhibited several parameters of inflammation in the wound site. This decrease in the early inflammatory phase of wound healing had a significant effect on later events in the wound healing process, namely a reduction in scar tissue formation, without disrupting reepithelialization or decreasing tensile strength. Our data suggest that in the absence of infection, adult wound healing is able to commence with decreased inflammation and that anti-inflammatory drugs may be used to improve the outcome of the repair process in the skin by limiting scar formation.

Biochemical evaluation of serum and flexor tenosynovium in carpal tunnel syndrome.

In total, 41 consecutive patients with "idiopathic carpal tunnel syndrome" and abnormal electrophysiologic findings who underwent carpal tunnel release were studied prospectively. The focus of this investigation was the evaluation of the levels of specific chemical mediators within the serum and flexor tenosynovium of these patients. Blood was collected from these patients within 1 week prior to carpal tunnel release, and flexor tenosynovium was obtained at time of surgery. Specimens were then analyzed to determine the levels of interleukins 1 and 6, prostaglandin E(2) (PGE(2)), and malondialdehyde bis diethyl acetal. These values were compared to those of controls who had no evidence of carpal tunnel syndrome. A significant increase was noted in the serum malondialdehyde and tenosynovial levels of malondialdehyde, interleukin 6, and prostaglandin PGE(2) compared to controls. The elevated levels of these biologic factors and the absence of interleukin 1 elevation support a noninflammatory ischemia-reperfusion etiology for so-called "idiopathic carpal tunnel syndrome" that causes progressive edema and fibrosis of the tissues within the carpal canal. These findings correlate with previous histopathology reports. We believe that "idiopathic carpal tunnel syndrome" is an "-osis" not an "-itis."

Determination of misoprostol free acid in human breast milk and serum by gas chromatography/negative ion chemical ionization tandem mass spectrometry.

To study an expected transition of misoprostol from human blood into breast milk, a novel method for the determination of its active metabolite misoprostol acid (MPA) was developed. MPA was determined in serum and breast milk samples by an isotope dilution assay using gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS). After addition of (15S)-15-methylprostaglandin E(2) (15-methyl-PGE(2)) as an internal standard, MPA was extracted from both matrices using a reversed-phase cartridge. The prostanoids were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride (PFBHA) and 2,3,4,5,6-pentafluorobenzyl bromide (PFBB) to the pentafluorobenzyl oxime (PFBO)-pentafluorobenzyl ester (PFB) derivatives. The sample was subjected to thin-layer chromatography with ethyl acetate-hexane (1 : 1 (v/v)) as the developing solvent. The corresponding zone was extracted. After derivatization to the trimethylsilyl ether, MPA was determined by GC/NICI-MS/MS using the [molecule (M) - pentafluorobenzyl (PFB)](-) ([P](-)) ions as precursor in the negative ion chemical ionization mode. The product ions used for quantification were [P - 2TMSOH - C(6)F(5)CH(2)OH](-) (MPA) and [P - 2TMSOH - C(6)F(5)CH(2)OH - CO(2)](-)(15-methyl-PGE(2)), respectively. The limit of quantification for MPA was approximately 1 pg ml(-1) in breast milk and serum samples. The correlation coefficients of the calibration curves for MPA were r > 0.997 in the 0.5-2000 pg ml(-1) range for both tested matrices.

Increased exhaled cysteinyl-leukotrienes and 8-isoprostane in aspirin-induced asthma.

The pathogenesis of aspirin-induced asthma (AIA) has not yet been clearly elucidated, although eicosanoid metabolites appear to play an important role. We hypothesized that levels of eicosanoids in exhaled air condensate are abnormal in patients with AIA and that they change in patients receiving steroid therapy. We measured cysteinyl-leukotrienes (cys-LTs), prostaglandin E(2) (PGE(2)), and leukotriene B(4) (LTB(4)), and also 8-isoprostane as a marker of oxidative stress, by enzyme immunoassay in exhaled breath condensate from patients with AIA (17 steroid naive; mean age, 41 +/- 23 years; FEV(1), 63%pred), 26 patients with aspirin-tolerant asthma (ATA) (11 steroid naive; mean age, 47 +/- 18 years; FEV(1), 69%pred), and 16 healthy subjects (mean age, 45 +/- 17 years; FEV(1), 93%pred). Cys-LTs were significantly higher in steroid-naive patients with AIA compared with steroid-naive patients with ATA and healthy subjects (152.3 +/- 30.4 and 36.6 +/- 7.1 versus 19.4 +/- 2.8 pg/ml; p < 0.05 and p < 0.05, respectively). Steroid-naive patients with AIA also had higher levels of 8-isoprostane than normal subjects (131.8 +/- 31.0 versus 21.9 +/- 4.5 pg/ml; p < 0.05). There were significantly lower levels of both cys-LTs and 8-isoprostanes in steroid-treated patients with AIA. There was no difference in either the PGE(2) or LTB(4) level between the patient groups. This is the first study to show that cys-LTs and 8-isoprostanes are elevated in expired breath condensate of steroid-naive patients with AIA, and that cys-LTs are decreased in steroid-treated patients. Exhaled PGE(2) levels are not reduced, so that it is unlikely that a deficiency of PGE(2) is an important mechanism, whereas exhaled LTB(4) levels are unchanged, indicating an abnormality beyond 5-lipoxygenase.

Subcellular distribution of prostaglandin-E2 and prostaglandin-F2 alpha in atrial tissue from patients with mitral valve disease.

The distribution of prostaglandin-E2 (PGE2) and prostaglandin-F2 alpha (PGF2 alpha) was studied in subcellular fractions isolated from homogenates of human atrial fresh tissue by differential centrifugation. Right and left atrial samples were excised from the same heart of six patients with mitral valve disease at the time of open heart surgery. The atrial fractions investigated were mitochondrial (8,500 g pellet), microsomal (100,000 g pellet) and cytosol soluble (100,000 g supernatant) fractions. After extraction of prostaglandins from the three atrial fractions and separation of PGE from PGF series by chromatography on silicic acid column, these prostaglandins were measured by radioimmunoassay. The results showed that PGE2 and PGF2 alpha were located mainly in the soluble cytosolic fraction of right and left atrial tissue (p < 0.001). Furthermore, the prostaglandins levels were higher in left than in right atria of these patients (p < 0.001). The relation between prostaglandins heart generation in response to elevated work load of mitral valve disease is discussed.

Subcellular distribution of prostaglandin-E2 and prostaglandin-F2alpha in atrial tissue from patients with mitral valve disease

The distribution of prostaglandin-E2 (PGE2) and prostaglandin-F2alpha (PGF2alpha) was studied in subcellular fractions isolated from homogenates of human atrial fresh tissue by differential centrifugation. Right and left atrial samples were excised from the same heart of six patients with mitral valve disease at the time of open heart surgery. The atrial fractions investigated were mitochondrial (8,500 g pellet), microsomal (100,000 g pellet) and cytosol soluble (100,000 g supernatant) fractions. After extraction of prostaglandins from the three atrial fractions and separation of PGE from PGF series by chromatography on silicic acid column, these prostaglandins were measured by radioimmunoassay. The results, showed that PGE2 and PGF2alpha were located mainly in the soluble cytosolic fraction of right and left atrial tissue (p<0.001). Furthermore, the prostaglandins levels were higher in left than in right atria of these patients (p<0.001). The relation between prostaglandins heart generation in response to elevated work load of mitral valve disease is discussed.

Interaction of chymotrypsin with carbetocin ([1-deamino-1-monocarba-2-O-methyltyrosine]-oxytocin).

The results of the present study describe the course of reaction and the products following chymotrypsin treatment of the oxytocin analogue carbetocin ([1-deamino-1-monocarba-2-O-methyltyrosine]-oxytocin). The metabolites were analyzed and identified through TLC, HPLC and mass spectrometry. The main product emerging after treatment of carbetocin with chymotrypsin is 9-desglycineamide carbetocin indicating preferential hydrolysis of the peptide bond between leucine at position 8 and carboxyterminal glycineamide. At the same time the stability of the bond between tyrosine at position 2 and isoleucine at position 3 appears significantly enhanced through the alkylation of the hydroxyl group of tyrosine.

Nitric oxide in human fetal membranes at term gestation: effect on prostaglandin E2 release.

OBJECTIVES: To examine the in vitro release of nitric oxide (NO) by human fetal membranes at term gestation and to investigate whether NO could stimulate prostaglandin E2 (PGE2) release by these tissues. STUDY DESIGN: Explants of fetal membranes (n = 17) were incubated either in the presence of sodium nitroprusside (NP), or L-Arginine (L-Arg), or bacterial lipopolysaccharide (LPS), or in the absence of the above substances (controls). NO and PGE2 concentrations in culture medium were assayed by the Griess reaction and radioimmunoassay, respectively. RESULTS: Fetal membranes spontaneously released NO in culture medium; incubation with NP increased the production of both NO and PGE2. L-Arg and LPS enhanced PGE2 output by tissues but did not influence NO production. CONCLUSIONS: An NO-generating activity might be present in human fetal membranes. NO stimulates PGE2 release by these tissues.

The transfer of prostaglandin E2 across ovine fetal membranes in vivo.

OBJECTIVE: This study investigated whether prostaglandin E2 (PGE2) can cross intact fetal membranes in vivo. METHODS: We have developed a novel ovine model using in vivo dialysis systems, positioned between the fetal membranes and decidua and in the amniotic cavity. Sheep were given 25 microCi, 50 ng [3H]PGE2 or 1 mg PGE2 to the amniotic cavity, and radioactivity or PGE2/PGEM concentrations in dialysates were determined. RESULTS: Endogenous basal PGE2 concentrations were significantly higher in extra-amniotic than in intra-amniotic dialysates (715 +/- 436 versus 80 +/- 31 pg/mL; mean +/- standard error of the mean; P < .05). After injection of [3H]PGE2 into the amniotic cavity, no radioactivity was detected in the extraamniotic dialysate, and this was not influenced by labor induced by ACTH administration to the fetus. In contrast, intra-amniotic injection of 1 mg PGE2 resulted in marked transfer of PGE2 across the fetal membranes to the extra-amniotic dialysis system. CONCLUSION: These results suggest that PGE2 can cross the ovine fetal membranes in vivo, escaping metabolism in the chorion.