Multidisciplinary team training reduces the decision-to-delivery interval for emergency Caesarean section.

BACKGROUND: Emergency Caesarean section is performed when the life of the pregnant woman and/or the foetus is considered at risk. A 30-min standard for the decision-to-delivery interval (DDI) is a common practice and is supported by national organisations including The Danish Society of Obstetrics and Gynaecology. Danish obstetric departments report the DDI to a national database. A national arbitrarily set standard recommends that 95% of ECSs should be achieved within the 30-min DDI standard. In 2011, 34.4% of ECSs, performed at our hospital, were achieved within the 30-min time frame. This study aims to evaluate the effect of a simulation-based team training programme on the proportion of ECSs achieved within a 30-min time frame. METHOD: We performed an interventional before-and-after study. We evaluated a total of one hundred 30-min ECSs before and after the intervention. The primary outcome of interest was the proportion of 30-min ECSs achieved within a 30-min time frame. RESULTS: A total of 20 team training courses were held during May/June 2013. These courses trained 239 of 252 team members (comprised of: 36 obstetricians, 45 scrub nurses, 83 midwives, 38 anaesthesiologists, 37 nurse anaesthetists) in handling of 30-min ECS. This corresponds to 95% of staff. The proportion of 30-min ECSs achieved within a 30-min time frame was higher after team training (87.5%, 95% CI 79.2-93.4%) compared with before training (74.0%, 95% CI 64.0-82.4%) (P = 0.017). CONCLUSION: Team training may contribute positively to an increase in the proportion of ECSs achieved within a 30-min time frame.

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.

Characterization of the rat myometrial contractile response to neuropeptide Y.

The in vitro contractile effect of neuropeptide Y (NPY) on rat myometrial strips was for the first time demonstrated and characterised, and the EC50 value estimated to be 267 +/- 87 nM. This effect is presumably mediated by the NPY1 receptor being responsible for postsynaptic effects throughout the peripherial nervous system, thus indicating a direct uterotonic effect of NPY. Further, the effect was demonstrated to the dependent on extracellular Ca2+. Short-term exposures to NPY markedly desensitized the tissue affecting subsequent responses to NPY as well as to oxytocin (OT). This desensitization was time and concentration-dependent, but lasted less than three hours. However, long-term infusions of NPY for 5 days increased to response to both NPY and OT. Long-term infusions of OT caused a marked decrease of the NPY response, and it is concluded that common pathways for up and down regulation of the myometrial responsiveness to several peptide hormones may exist.

Effects of the non-peptide inhibitor OPC-21268 on oxytocin and vasopressin stimulation of rat and human myometrium.

OPC-21268 (1-[-1-[4-(3-acetylaminopropoxy)benzoyl]-piperidyl]-3,4- dihydro-2(1H)-quinolinone), a non-peptide vasopressin V1 receptor antagonist, inhibited oxytocin- and vasopressin-induced contractions of myometrial strips from rats and from full-term pregnant women. Administered intravenously in rats the drug also inhibited uterine contractions caused by infusion of oxytocin. When incubated with purified plasma membranes from rat or human myometrial tissue, OPC-21268 inhibited the specific receptor binding of tritiated oxytocin and vasopressin in a dose-dependent and reversible way.

The nature of receptor binding of oxytocin in myometrial tissue.

The dissociation course of the hormone receptor complexes of rat myometrial oxytocin receptors was studied. The dissociation course was biphasic with a major component displaying an almost irreversible binding character (time constant 0.003 min-1). This irreversibility was independent of hormonal status of the myometrium as well as the type of divalent cation present in the medium, and was not caused by endocytosis of the receptor. However, as addition of EDTA caused an immediate dissociation of all receptor binding, the irreversibility must be of a non-covalent character. It is suggested that new analysis methods for receptor kinetics including the possibility of partly irreversible binding mechanisms should be considered.

The potential of perturbed angular correlation of gamma rays as a tool for dynamic studies of peptides/proteins.

Four peptides and serum albumin have been derivatized with the bicyclic anydride of diethylenetriamine-pentaacetic acid. Procedures were developed to isolate the labelled species and determine the degree of derivatization. By using perturbed angular correlation of gamma-ray spectroscopy it is possible, through the determination of rotational correlation times, to decide whether labelled peptides interact with other molecules (receptors). In the case of the peptide cholecystokinin it is shown that the interaction between the peptide and its corresponding polyclonal antibody can be determined down to 1 pmol hormone. Experiments on 111In- and 111mCd-labelled Gly-Trp showed that, where the 111Cd PAC spectrum directly reflected the rotational motion of the molecule, the 111In PAC spectrum was affected by the nuclear transitions to 111mCd.

Characterization of the endothelin receptors of rat myometrial plasma membranes.

Binding of 125I-endothelin-1 (human endothelin) to purified rat myometrial plasma membranes was assayed. Analysis of binding data displayed binding to two groups of receptors, a high affinity low capacity pool (Kd = 0.22 nM), and a low affinity high capacity pool (Kd = 173 nM). The high affinity pool most likely originated from contamination with vascular cell membranes, and it was concluded that the endothelin affinity to myometrial tissue is low, which is in agreement with earlier reports on the uterotonic potency.

Correlation between myometrial receptor affinity, lipophilicity and antagonistic potency of oxytocin analogues in the rat.

Purified myometrial plasma membrane fractions were prepared from rats treated with oestradiol to induce oestrus. The binding affinities of 11 antagonistic oxytocin analogues to the oxytocin receptor of the plasma membranes were measured. Furthermore, lipophilicity of the peptides was assessed by reversed-phase high pressure liquid chromatography. No significant correlation was found between lipophilicity of the analogues and values for antagonistic potencies or binding affinities. Also, receptor-binding affinity did not correlate with in-vitro antagonistic activity whereas a significant correlation was obtained between binding affinities and in-vivo antagonistic potency for analogues void of partial agonist properties. It is concluded that neither receptor affinity nor lipophilicity in the analogues can predict the potency of the antagonists in vitro. However, receptor affinity was found to be a relatively good predictor of the in-vivo potency, while the usefulness of measuring antagonistic potency in vitro is questioned.

Receptor-binding characteristics and contractile responsiveness of the myometrium following prolonged infusion of bradykinin and oxytocin in rats.

Binding of [3H]oxytocin to purified myometrial plasma membranes was unaffected by continuous infusion of bradykinin over 5 days in rats pretreated with oestradiol 2 days before collection of tissue. In contrast, oxytocin treatment resulted in a 76% decrease in maximal binding of [3H]oxytocin and thereby in oxytocin receptor concentration without affecting the dissociation constant. The KM value (molar concentration giving half maximal contraction) of isolated uterine strips stimulated with oxytocin was increased and maximal contractile responses were reduced following oxytocin infusions. The binding of [3H]bradykinin to purified plasma membranes was influenced by treatment with both oxytocin and bradykinin. Bradykinin infusions down-regulated the bradykinin receptor concentration by 19%, while the receptor affinity remained unchanged. Maximal contraction (Emax) values of isolated strips stimulated with bradykinin exhibited a slightly attenuated response and KM values were significantly enhanced. Long-term treatment with oxytocin down-regulated myometrial bradykinin receptors by 31%. In addition, oxytocin infusions caused Emax to decrease and KM to increase in experiments with isolated uterine strips stimulated with bradykinin. It is concluded that the down-regulation of oxytocin and bradykinin receptors following prolonged exposure to oxytocin may result from changes in a common pathway for intracellular peptide receptor processing. Likewise, the increased KM values of isolated myometrial strips (despite unchanged dissociation constants) suggest that prolonged oxytocin treatment affects the coupling between receptor activation and contractile response.

Oxytocin receptors and contractile response of the myometrium after long term infusion of prostaglandin F2 alpha, indomethacin, oxytocin and an oxytocin antagonist in rats.

Binding of [3H]oxytocin to isolated myometrial plasma membranes was not affected by the presence of prostaglandin (PG)F2 alpha or E2 in the incubation medium. Long-term treatment with PGF2 alpha or indomethacin had no effect on oxytocin receptor concentrations and dissociation constants of myometrial plasma membranes nor on maximal contractility or KM values of isolated uterine strips exposed to oxytocin. Infusion of oxytocin for 5 days in non-pregnant rats resulted in a decrease in oxytocin receptor concentrations in myometrial plasma membranes whereas the binding affinity to oxytocin was unaffected. Isolated uterine strips from similarly treated rats showed a reduced maximal contractile response to oxytocin and an elevated KM value, possibly indicating an influence of oxytocin on the coupling between receptor occupancy and contractility. Treatment for 5 days with desamino1-[D-Tyr(O-ethyl)2-Thr4-Orn8] oxytocin (an oxytocin antagonist) increased the concentration of myometrial oxytocin receptors. In addition KD values of these receptors were elevated. The present results indicate that prolonged exposure to oxytocin leads to a down-regulation of the myometrial receptor concentration, which is not caused by ligand-receptor interaction in itself. The concerted effect of oxytocin and prostaglandins on myometrial contraction does not appear to involve modulation of the oxytocin receptor by prostaglandins.

Uterotonic activity and myometrial receptor affinity of 1-deamino-1-carba-2-tyrosine(O-methyl)-oxytocin.

The contractile effect of the analogue 1-deamino-1-carba-2-tyrosine(O-methyl)-oxytocin (carbetocin) on isolated myometrial strips from rats was compared with that of oxytocin. The uterotonic activity of the analogue was 15 +/- 3 IU/mg as compared with 438 +/- 41 for oxytocin, however, the response was more prolonged and could not be abolished by washing of the preparation. Despite the low biological activity of carbetocin, its binding affinity to receptors of isolated myometrial plasma membranes was of the same order of magnitude as that of oxytocin. On the basis of the present results it is concluded that a longer half-life of the analogue at the receptor compartment may be a contributing factor to the prolonged uterotonic effect observed in vivo.

Processing and secretion in the neurohypophysis. Stability of isolated secretory vesicles and role of internal pH.

A possible role of low pH in secretory vesicles for processing and secretion in the neurohypophysis was investigated. Subcellular fractionation of guinea-pig neural lobes revealed that a proton present in the membranes from this tissue could not be ascribed to secretory vesicles. However, a proton pump was found in coated microvesicles. Secretory vesicles isolated from rats and guinea pigs were stable under conditions known to lyse secretory vesicles from the adrenal medulla owing to the generation of a proton gradient. These results suggest that the internal pH of secretory vesicles from the neurohypophysis is closer to neutral than is the pH in chromaffin secretory vesicles. Processing of a neurophysin-glycopeptide intermediate from the biosynthesis of vasopressin in intact secretory vesicles incubated in vitro was activated by the addition of NH4Cl, known to increase the intravesicular pH. This activation of neurohormone processing was also apparent in isolated nerve endings incubated in the presence of NH4Cl, suggesting that NH4Cl can also be used to increase the intravesicular pH in intact nerve endings. However, NH4Cl did not affect the secretion of neurohormones, indicating that a low intravesicular pH is not important for exocytosis in the neurohypophysis. Our results indicate that a low pH generated during processing by mechanisms other than ATP-dependent proton transport may inhibit the processing enzymes, thereby preventing extensive breakdown of neurohormone precursors.