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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A radioimmunoassay (RIA) for oxytocin (OT) in urine is described. 125I-OT was prepared, and antibodies were raised in rabbits against OT coupled to bovine serumalbumine. This allowed us to set up of RIA for OT which limit of detection is 1.25 pg/tube (0.6 microU). The use of an extraction procedure using CG50 Amberlite is essential. The recovery after extraction reaches 70.5%. pH 5 is the optimum pH were urine samples must be stored. The superposition of the elution peak of endogenous OT on that of exogenous hormone is an argument in favour of the validity of such an extraction procedure. Daily urinary excretion of OT reaches 9.58 mU +/- 3.48 in 18 healthy young men.
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PMID:[Radioimmunoassay of urinary oxytocin in man]. 4 Jun 75

The reputation of the predictive accuracy of a negative oxytocin challenge test (OCT) has been somewhat tarnished by recent sporadic reports of intrauterine fetal death relatively soon after a negative OCT. We have analyzed probable causes and the possibilities of reducing to a minimum "false-negative" results of the OCT. In particular, several of these reports did not take into account the loss of baseline fetal heart rate (FHR) variability recorded during the OCT and, in the absence of late decelerations, the OCT was interpreted as negative. We suggest that recordings showing a loss of baseline beat-to-beat FHR variability and a negative OCT illustrate a complete inability of the fetus to react to any stimulus and that, in these cases, a negative OCT should in no way be reassuring, but rather a warning sign of severe fetal compromise. Two cases are presented to illustrate this phenomenon.
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PMID:Loss of beat-to-beat variability and a negative oxytocin challenge test: an ominous prognostic sign. 4 63

Both biophysical and biochemical techniques may be used to diagnose fetal distress. Fetal heart rate monitoring should be thought of as a screening technique to define a population at significant risk for fetal acidosis. The addition of fetal scalp blood sampling improves the clinician's diagnostic accuracy. The hallmark of treatment is to alleviate the stress on the fetus, to restore intervillous and cord blood flow, and, hence, to improve fetal oxygenation. This improvement may be accomplished by (1) discontinuing oxytocin, (2) correcting maternal hypotension, (3) administering oxygen to the mother, and (4) attempting to alleviate cord compression by changing the relationship of the fetal presenting part to the umbilical cord and pelvis.
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PMID:Diagnosis and management of fetal distress. 4 83

Mucosal acidification to pH 6.5 reduced by 88% the oxytocin- (2.2 x 10(-8) M) elicited increase of water permeability in frog urinary bladder. Mucosal alkalinization (pH 10.5) increased by as much as 200% the response to the same concentration of oxytocin. These effects were not observed when supramaximal concentrations of oxytocin were imployed. Similar changes were found when the serosal pH was modified. The hydrosmotic responses elicited by serosal hypertonicity or cyclic AMP plus theophylline were also affected by mucosal or serosal changes of the hydrogen in concentration, suggesting an effect at a post-cyclic AMP level. Important interactions were found between luminal pH and serosal hypertonicity when experimental conditions were employed similar to those observed in the collecting duct of mammalian nephron. Freeze-fracture studies showed that the number of intramembranous aggregates of particles induced by ADH in the luminal membrane was reduced by mucosal acidification and augmented by an increase in medium pH.
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PMID:Influence of mucosal and serosal pH on antidiuretic action in frog urinary bladder. 4 16

Case reports of three patients who had fits as a consequence of hyponatremia are presented. Each patient was in spontaneous labor at term and received conventional doses of oxytocin for augmentation. The pathogenesis, diagnosis and treatment of this entirely iatrogenic condition are discussed. The differences between these and similar cases in the literature are stressed.
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PMID:Hyponatremic fits in oxytocin-augmented labors. 4 79

Sixty patients with previous stillbirths were given active antepartum, intrapartum and early postnatal care. A majority (75%) had a history of repeated stillbirths, and responsible pathology was detected in 55% of the cases. In the present pregnancy, 90% of the patients suffered complications, each of which was diagnosed and treated. Most of the group were hospitalized. Tests for serial urinary estrogens were done for 75% of the women. Other special assessments of maturity with amniotic fluid, oxytocin challenges and fetal monitoring were carried out in selected cases. After confirming maturity and degree of antepartum stress, labor was induced when appropriate. There was liberal recourse to cesarean section (18.3%), but no maternal mortality. Overall fetal salvage was 75%.
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PMID:Active management of high-risk pregnancy. 4 86

During suckling, anaesthetized lactating rats release regular (about every 7 min) but brief pulses of oxytocin (0.5--1.0 mu.) which produce single transient increases in intramammary pressure. Drugs which selectively impair synaptic transmission were used to determine the role of dopamine and noradrenaline in regulating this natural reflex. Diethyldithiocarbamate (100--200 mg/kg, i.v.) and alpha-methylparatyrosine (100--400 mg/kg, i.v.) which inhibit the synthesis of catecholamines both blocked the suckling-induced release of oxytocin. The milk-ejection reflex was also inhibited in a dose-dependent manner by the intravenous administration of the dopamine antagonists, fluphenazine (0.7 mg/kg), pimozide (1.4 mg/kg), cis-dupenthixol (4.5 mg/kg) and metoclopramide (6.0 mg/kg), and caused a significant inhibition P less than 0.01) of the reflex in 50% of the rats tested. The alpha-adrenoceptor antagonist phenoxybenzamine (1.4 mg/kg) was similarly effective. Dopamine (40 micrograms), bromocriptine (10 micrograms), apomorphine (100 micrograms), noradrenaline (10 micrograms) and phenylephrine (2 micrograms) injected into the cerebral ventricles evoked a sustained release of oxytocin which produced multiple increases in intramammary pressure; isoprenaline (4 micrograms) was ineffective. The release of oxytocin evoked by dopamine and noradrenaline was prevented by cis-flupenthixol and phenoxygenzamine respectively. None of the drugs used affected the mammary sensitivity to exogenous oxytocin nor were their actions modified by pretreatment with propranolol (1 mg/kg). The results suggest that the neural pathway for the reflex release of oxytocin during suckling in the rat contains both dopaminergic and noradrenergic synapses, the latter acting through alpha-adrenoceptors and being distal in the pathway to the dopaminergic component.
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PMID:Dopaminergic control of oxytocin release in lactating rats. 4 80

In a prospective randomized study spontaneous and oxytocin induced labor "for convenience" have been compared with respect to uterine activity, duration of labor, the condition of the fetus and the newborn infant. The study consists of 84 normal patients, of whom 43 were induced at full term by amniotomy and oxytocin infusion using the Cardiff Infusion System Mark II; 41 patients served as controls. No difference in maternal age, number of previous pregnancies and pelvic score one week before the day of delivery were found between the groups. The following parameters were calculated: duration of labor, uterine activity, amount of bleeding in the third stage of labor, number of early and late decelerations as well as number of episodes of bradycardia in the CTG-recordings, birth weight, Apgar score one and five minutes post-delivery and blood gases in mother and child 60 seconds after delivery. No significant differences between the two groups were found. It is concluded that there are no increased risks to mother or fetus compared to normal labor provided that there is cephalic presentation and normal pregnancy, careful selection with respect to the length of pregnancy and the condition of the cervix and that the Cardiff infusion system is used with intrauterine pressure recording and continuous fetal heart monitoring.
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PMID:Spontaneous labor and elective induction--a prospective randomized study. I. Effects on mother and fetus. 4 68

The various neurohumoral and intrinsic factors that control the uteroplacental hemodynamics in health and disease and in responses to physiologic and pharmacologic stimuli have been reviewed. The following conclusions may be derived: We still need improvement in our methodology of monitoring uterine blood flow. The present methods, which have some reliability, are not easily applicable to human subjects and even in animals their use presents problems of accuracy and sensitivity with which the investigator must become familiar. The marked and progressive increase in uterine blood flow that occurs during pregnancy is caused by complex factors, some of which are hormonal and hemodynamic in nature. The increased vascularity of the pregnant uterus and the opening of the arterioles during the process of formation of the intervillous space are important factors that facilitate the increase in uterine blood flow. The increment seems to be totally derived from the increment in the cardiac output that occurs during pregnancy. There seems to be no redistribution among the regional blood flows of the body. In the anesthetized condition the blood flow to the uterus depends largely on the perfusing pressure; the critical closing pressure seems to be around the 40 mm Hg level. This linear flow-pressure relationship does not, however, apply to the unanesthetized condition. A rise or fall in the perfusing pressure in the conscious state may be accompanied by an increase or decrease in the uterine blood flow, depending on the underlying mechanisms. Factors that lead to alpha-adrenergic stimulation produce an increase in uterine vascular resistance and a decrease in flow, irrespective of the status of the perfusing pressure. beta-adrenergic stimulation may increase uterine blood flow either through their vasodilating action or through their myometrial relaxing effects. Hypertensive diseases are most often accompanied by a decrease in uterine blood flow, whereas hypoxic states may decrease the flow even though the arterial pressure may not change significantly. It is extremely risky to extrapolate from information obtained in the anesthetized animal to the unanesthetized, conscious animal. Likewise, data obtained from normotensive conditions may not hold true for the hypertensive or hypotensive states. This is of particular relevance when one is dealing with the effects of pharmacologic agents that act on the cardiovascular system. Uterine contractions, whether induced through spontaneous or oxytocin-induced labor, produce a decrease in uterine blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Control of the uteroplacental circulation in health and disease. 4

The successful termination of 19 consecutive late 1st and 2nd trimester pregnancies using a combination of intravenous prostaglandin E2 (PGE2) and oxytocin (Syntocinon) is reported. PGE2 (5 mg in 500 ml of 5% glucose) was initially infused at the rate of 2.5 mcg/minute and then increased to 5 mcg/minute after half an hour. The infusion was increased to a maximum of 10 mcg/minute. Oxytocin was infused 2 hours after the PGE2 at a constant rate of 128 mU/minute. Mean total dose of PGE2 used was 5.9 mg at an overall rate of 6.1 mcg/minute. Average induction/delivery interval was 16 hours, with only 1 patient taking more than 24 hours. Abortion was complete in 13 cases (68%). Vomiting occurred in 13 women; pain was minor and was controlled by pethidine. Mild and transient thrombophlebitis was also reported. There were no reported cases of diarrhea and or cervical damage. Compared to the use of intravenous PG alone, PG given intraamniotically alone or with intravenous oxytocin, and PG given extraamniotically alone or with intravenous oxytocin, this study shows that a combination of intravenous PGE2 and oxytocin at the dose level described is closer to meeting all the desired criteria for the acceptability of any abortion method (ease and safety of administration, side effects, lengths of induction delivery interval, and effectiveness in terms of success rate and uterine evacuation).
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PMID:Letter: Intravenous prostaglandins and oxytocin for mid-trimester abortion. 4 97


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