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At least 883 records · Page 49Linked to original sources
PubMed1969

The effect of metals on the S-S polypeptide receptor in depolarized rat uterus.

1. Metals potentiate the contractile effects of S-S polypeptides in depolarized rat uterus. Their order of potency is Co(++)>/=Co(+++)>/=Mn(++)>/=Ni(++)>/= Mn(+++)>Zn(++)>/=Mg(++)>Fe(++)>Fe(+++)>/= Ca(++)>Be(++)=Sr(++)=Ba(++)=Cu(++)=O.2. S-S polypeptides with relatively weak oxytocic activity such as lys-vasopressin, arg-vasopressin and orn-vasopressin are strongly potentiated by metals while highly active polypeptides such as oxytocin are weakly potentiated.3. Potentiation by metals was specific for S-S polypeptides; other polypeptides (bradykinin, hypertensin) as well as acetylcholine and isoprenaline were unaffected.4. Potentiation by metals occurs rapidly and is fully reversible. In all cases some activity was retained by S-S polypeptides even in the complete absence of metals.5. A scheme which could account for the observed effects has been formulated. This assumes the formation of a ternary complex between receptor, metal and polypeptide leading to improved alignment between polypeptide and receptor.6. Analogies are discussed between metal enzymes and the S-S polypeptide receptor for which the term metal receptor is proposed.

Angiotensin II↗
PubMed1970

Study of the effects of progesterone therapy on the stilboestrol-induced sensitivity of isolated uteri of hypophysectomized rats.

1. In intact rats progesterone (50 mg/kg) antagonized the effect of stilboestrol (100 mug/kg) on the vaginal smears and the uterine sensitivity. The uterine sensitivity to acetylcholine, oxytocin and 5-hydroxytryptamine was decreased by 6.8, 64 and 14.8 times, respectively, as compared with uteri removed after stilboestrol injections.2. Progesterone therapy in hypophysectomized rats also antagonized the effect of stilboestrol on the vaginal mucosa and on the uterine sensitivity to drugs. The sensitivity to acetylcholine, oxytocin and 5-hydroxytryptamine was decreased by 6.2, 50 and 14.5 times, respectively. Similar results were obtained on uteri removed from sham-hypophysectomized rats.3. On the basis of these results it is suggested that the hypophysis does not play any part in the desensitization of the myometrium to the oxytocic drugs and in the changes found in the vaginal mucosa after progesterone therapy.

Acetylcholine↗
PubMed1977

Time course of lithium-induced alterations in renal and endocrine function in normal and Brattleboro rats with hypothalamic diabetes insipidus.

1. A lithium chloride (1.1 g/kg) supplemented diet was given to Long Evans (LE) and Brattleboro (DI) rats to investigate its actions in the presence (LE) and absence (DI) of vasopressin. 2. During the first 24 h, Li-supplemented LE rats displayed an initial water deficit (drinking less than renal output), increased plasma antidiuretic (ADH) titres and slightly increased plasma renin activities (PRA) and plasma osmolarities. Such changes were qualitatively similar to those seen in rats fed a normal diet, but deprived of water for 24 hours. After 12 days, the Li-supplemented rats had elevated plasma ADH titres, but reduced pituitary oxytocic and antidiuretic activities. 3. The urinary losses of Na, K and Cl exceeded dietary intakes in LE rats on the introduction of the Li-supplement, and the urinary osmolarity fell by 50%. Electrolyte balances were gradually re-established, although drinking and urine production increased in parallel to reach twice the control values by day 12 of the supplement. 4. Aldosterone and corticosterone secretory rates and their peripheral plasma concentrations were unchanged both after 24 h and 28 days of the Li-supplement. 5. Li elicited no water deficit or saluresis in DI rats, and although the polyuria and polydipsia were exacerbated, urinary osmolarity did not change over the 12 day observation period. 6. Li increased Ca excretion in both rat types; after 12 days the PRA of DI but not LE animals were increased. 7. It is concluded that the overall renal actions of Li are tempered by vasopressin rather than adrenocorticosteroids.

Adrenal Cortex↗
PubMed1987

Effects of oxytocin-antagonist injections on luteal regression in the goat.

Intra-arterial administration of 0.25 ml physiological saline to the non-pregnant goat between days 12 and 20 of the oestrous cycle did not affect luteal regression, which was characterized by decreasing peripheral plasma progesterone concentration, beginning on day 13 of the oestrous cycle, and an increase in the plasma concentration of 13, 14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) as oestrus approached on about day 20. Intra-arterial administration of oxytocin antagonist (OA) in saline at a dose of 0.2 microgram kg-1 body weight to goats between days 12 and 20 of the cycle significantly (P less than 0.001) delayed luteal regression beyond day 20 (to day 26). Injection of OA maintained plasma progesterone secretion at 4-5 ng ml-1 till day 23 of the cycle and suppressed the increase in PGFM concentration. Corpus luteum extract (100 microliters) of OA-treated animals released a significant (P less than 0.001) amount of PGF2 alpha from rat uterus in vitro as did authentic oxytocin. This oxytocic material failed to release PGF2 alpha during luteolysis in the goat, suggesting that oxytocin receptors for PGF2 alpha release may be occupied by OA. It is concluded that oxytocin-receptor interaction in the uterus may be the stimulus for PGF2 alpha release which triggers luteal regression in the goat.

Animals↗
PubMed1981

Labour-onset pre-eclampsia.

In a consecutive series of 1,201 singleton pregnancies with pre-eclampsia, the onset occurred during labour in 290 (24.1%). There was no difference between the primiparous and parous patient in this respect (25.9% v 20.7%; P less than 0.10). The tendency for pre-eclampsia to develop during labour increased with advancing maturity of the pregnancy and seldom occurred before 38 weeks of gestation; this was again equally true of the primiparous and parous patient, as was the incidence of severe hypertension (diastolic pressure greater than 110mm Hg) (36.1% v 34.1%). The high incidences of severe hypertension (35.5%), proteinuria (41.7%), and eclampsia (2.1%), and the 1 maternal death testified to the severity of the disease process and the need for aggressive management. After delivery, the clinical signs tended to subside rapidly, but the early third stage of labour was a time of maternal risk, irrespective of whether ergometrine or Syntocinon was the oxytocic agent administered. Analysis of perinatal results showed that the risk to the fetus was minimal.

Adult↗
PubMed1986

Oxytocin induced second trimester uterine rupture.

A case of oxytocin induced rupture of an unscarred uterus during the second trimester is presented. While rupture of the uterus by oxytocic agents in the second trimester has previously been documented, this case is unusual in that fetal parts were palpable through the cervical os, delaying diagnosis and definitive management. Digital palpation of fetal parts through the cervix does not preclude the diagnosis of fetal extrusion secondary to uterine rupture.

Adult↗
PubMed1988

Vaginally administered 16,16-dimethyl-PGE1-methyl ester (Gemeprost) to induce termination of pregnancy after the first trimester.

The results of the first 40 patients, whose pregnancies were terminated using Gemeprost vaginal suppositories are presented. The indication for termination of pregnancy was either fetal abnormality, or fetal death in utero. The mean gestational age was 20.9 +/- 4.4 weeks. 82.5% of patients were delivered within 24 hours, following a mean number of 3.9 +/- 1.3 pessaries. Side-effects were uncommon, and the procedure was well tolerated, with 30% of patients requiring no analgesia, and 60% receiving narcotic analgesia only. The results obtained compare favourably with the overseas experience with this method. Augmentation with oxytocic agents is of questionable value, and routine evacuation of the uterine cavity, under general anaesthesia seems unnecessary. Administration is simple and well tolerated by patients, and this method of pregnancy interruption appears safe, efficient and superior to extra-amniotic infusion of PGF2 alpha.

Abortifacient Agents↗
PubMed1994

The safety of vaginal prostaglandin F2 alpha for the stimulation of labour.

In an audit of 15,102 consecutive deliveries between 1986 and 1991, 3,168 labours were induced with intravenous oxytocin and 824 with 40 mg prostaglandin F2 alpha (PGF2 alpha) vaginal gel. Four hundred and twenty women received PGF2 alpha alone and 404 received PGF2 alpha followed by oxytocin. The main aim of the study was to audit the safety of PGF2 alpha gel to stimulate labour. There were no maternal or neonatal complications attributable to this therapy. In particular, there were no cases of uterine rupture or hyperstimulation requiring surgical or pharmacological intervention. There was little difference in the evidence for fetal distress between induction methods. Although the prostaglandin and oxytocin groups were not comparable in all respects, the results of this large retrospective study confirmed the results of smaller prospective randomized trials showing a significantly shorter labour and reduced analgesia, surgical delivery and postpartum haemorrhage rates in women treated with PGF2 alpha alone. This is the largest reported series of PGF2 alpha induced labours and provides evidence of its safety and is in keeping with physiological data suggesting that PGF2 alpha is the main prostaglandin and oxytocic associated with normal progressive labour. Its apparent safety and potential to reduce both intervention in labour and postpartum complications merits greater attention.

Adult↗
PubMed1994

The use of syntocinon in the management of excessive fluid absorption during endometrial ablation.

Five cases of intravenous oxytocin use during endometrial laser ablations complicated by excessive fluid absorption are reported. In each of the 5 cases it was possible to measure the rate of fluid absorption before and after the administration of this medication. There was a marked reduction in fluid absorption in 4 of the 5 cases, although the small number in the study did not allow statistical significance to be reached. The clinical benefit observed supports earlier work at this institution which suggests that oxytocic agents may be of value in cases of excessive fluid absorption through their action in contracting the myometrium and thereby compressing myometrial veins.

Absorption↗
PubMed1998

Sublingual glyceryl trinitrate for uterine relaxation at Caeserean section--a prospective trial.

We report a prospective study on the use of sublingual glyceryl trinitrate at Caesarean section to induce uterine relaxation; 23 women were entered into the study with both emergency and elective cases considered. A metered dose spray was used to deliver a dose of 400 or 800 microgrammes of glyceryl trinitrate to the women. There were no major side-effects of hypotension or postpartum haemorrhage. The mean maximal systolic blood pressure drop in the patients following drug administration was 18% of the systolic pressure prior to drug administration. Subjective assessment of uterine tone showed the uterus to contract well postdelivery in response to standard oxytocic regimens. Minimal maternal side-effects were reported. We conclude that glyceryl trinitrate is a safe form of uterine relaxation at Caesarean section which may be used in emergency situations and may also be given prophylactically in cases such as breech presentation and in delivery of the preterm infant where fetal trauma is possible. The use of a metered-dose sublingual spray is ideally suited to obstetric practice, being both easy to use and also rapidly administered.

Administration, Sublingual↗
PubMed2006

Uterine rupture: preventable obstetric tragedies?

BACKGROUND: Although ruptured uterus is nowadays a rare obstetric emergency in Western countries, it is still alarmingly common in developing countries, where it remains a major cause of maternal mortality and morbidity. AIMS: To review the recent experience of uterine rupture at a tertiary obstetric unit in eastern Nepal and to recommend improvements in the current management of labour, especially obstructed labour, in a poorly resourced country. METHODS: All cases of uterine rupture managed from March 2002 to March 2006 were identified retrospectively, and details were retrieved from medical records. RESULTS: Fifty-two women suffered from uterine rupture during the four-year period, approximately one woman per month. Most were unbooked multigravidae, with no antenatal care. They nearly all began labour at home in the absence of a skilled birth attendant. After prolonged labour, usually prolonged second stage, various interventions had often been attempted at home or in other health facilities before admission. Most were shocked and required urgent laparotomy and blood transfusion. Many required intensive care and ventilatory support. Forty-six per cent required hysterectomy and 5.8% subsequently suffered from a urogenital fistula. The maternal mortality rate in this series was 13.5%, and the stillbirth rate was 94.2%. CONCLUSIONS: Unsafe obstetric practices were identified, especially the injudicious use of oxytocic drugs and fundal pressure in prolonged second stage. Several achievable improvements in obstetric care are recommended, particularly aimed at reducing the delay in women reaching emergency obstetric care when labour is prolonged.

Adolescent↗
PubMed1989

Views of mothers and midwives participating in the Bristol randomized, controlled trial of active management of the third stage of labor.

Mothers and midwives who had participated in the Bristol randomized controlled trial of active versus physiologic management of the Third Stage of Labor were asked for their views. One hundred ninety-one mothers (11% of the total randomized) and 49 midwives completed self-administered questionnaires. Both mothers and midwives commented adversely about the length of the third stage under physiologic management. In general, their views were in accord with the conclusions of the main trial (based on clinical data, including maternal blood loss, length of third stage, need for therapeutic oxytocic agents, and specified neonatal morbidity) in favor of continuing with the current practice of active management.

Attitude of Health Personnel↗
PubMed1986

Vasopressin and oxytocin levels in human neonates. Relationships with the evolution of labour and beta-endorphins.

In order to find out whether arterial and venous cord levels of vasopressin (VP) and oxytocin (OT) might be linked to one or more obstetric parameters and to beta-endorphin (BEP) secretion, 42 successively delivered neonates were studied. Arterial and venous cord blood levels of these peptides were not statistically different whenever the neonates were born vaginally with or without foetal distress, after induction of labour by oxytocic drugs, or by elective caesarean section. BEP levels in cord and maternal blood do not seem to be linked with AVP or OT. The results of the group of infants born after uncomplicated vaginal delivery analyzed with regard to obstetric parameters, led to the following conclusions: arterial cord VP correlated with venous cord VP, with arterial cord OT and with the duration of membrane rupture; arterial cord OT correlated with venous cord OT and with the time taken by the cervix to dilate from 5 to 10 cm, suggesting that the foetal pituitary gland is sensitive to the evolution of labour.

Cesarean Section↗
PubMed1983

Maternal "en face" orientation during the first hour after birth.

Data are presented on the amount of time that 97 mothers spent in the "en face" position in the first hour postpartum, during which time contact between mother and infant was uninterrupted. The mean times varied with cultural background, relationship with the child's father, attitude toward childbirth, and administration of oxytocics.

Attitude↗
PubMed1969

A study of the parameters of electrical stimulation of unmyelinated fibres in the pituitary stalk.

1. The milk-ejection response in lactating rabbits has been used to study the effect of electrical stimuli of different types applied to the supraopticohypophysial tract in the pituitary stalk.2. Sine-wave alternating-current pulses were compared with balanced biphasic square-wave pulses of the same frequency and peak-to-peak current strength. At a pulse duration of 2-4 msec the square-wave stimulation was less effective than the sine wave, but at a pulse duration of 8 msec and over, more effective.3. Above threshold levels of 0.12 mA for the current strength, and of 0.5 msec for the pulse duration, the response increased with increasing current strengths to 2.4 mA and increasing pulse durations to 10 msec.4. With constant and effective strength and duration of the pulse a slight diminution of the response was seen as the frequency was diminished from 100/sec to 50/sec. Further diminution in the frequency revealed that at some point between 50 and 10 c/s a sudden abrupt diminution in the magnitude of the responses occurred over a small range of frequency. This was a reversible phenomenon and it is suggested that it may be related to neurosecretory events occurring in the nerve terminals.5. Stimuli with parameters within the ranges mentioned above are effective in eliciting an oxytocic response on the uterus in the rabbit and ovulation responses (when applied to the hypothalamus) in rats and rabbits. It appears likely that stimuli with such parameters are suitable for experiments concerned with stimulation of the hypothalamus.

Animals↗
PubMed1962

Angiotensin II: its metabolic fate.

Randomly labeled tritiated angiotensin has been prepared with a specific activity of 300 microc/mg and with undiminished pressor and oxytocic activity. After infusion, angiotensin accumulated in the kidneys, adrenal glands, and uterus. Thirty minutes after infusion high levels of radioactivity appeared in brain, but the electrophoretic mobility differed from that of angiotensin II. Incubation of angiotensin with hemolyzed human red blood cells or diluted human plasma rapidly inactivated the pressor activity with production of metabolic products separable by paper chromatography. But if undiluted plasma is used with incubation up to 6 hours, no loss of activity occurs.

Adrenal Glands↗
PubMed1986

Structure of pressinoic acid: the cyclic moiety of vasopressin.

Arginine vasopressin consists of a 20-membered, disulfide-linked macrocyclic ring system called pressinoic acid to which is attached a COOH-terminal tripeptide. The molecular conformation of pressinoic acid has been determined from single crystal x-ray diffraction data. The 20-membered macrocyclic ring, stabilized by two intramolecular hydrogen bonds, has a type I beta-bend centered on Gln4 and Asn5 and a highly distorted type II' bend centered on Phe3 and Gln4. In vasopressin the Asn5 side chain extends away from the macrocyclic ring system and hydrogen bonds to the terminal tripeptide, but in pressinoic acid the Asn5 side chain lies over the molecule and forms a strong hydrogen bond to the nitrogen of Tyr2. The absence of pressor activity in pressinoic acid may be a result of both the loss of the COOH-terminal tripeptide and the incorrect orientation of the Asn5 side chain. Whether this class of hormones has pressor or oxytocic activity is determined by the orientation of the Tyr2 side chain, that is, whether it is extended away from or over the ring system, respectively. In pressinoic acid, the Tyr2 side chain is in the expected "pressor conformation," that is, extended away from the ring system, and is stabilized through a hydrophobic interaction with the Phe3 side chain. Thus, the conformation of the pressinoic acid molecule partly explains the activity of vasopressin-like hormones.

Arginine Vasopressin↗