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

Although only about 8 per cent of pregnancies end prematurely, as much as 75 per cent of perinatal deaths are due to prematurity. Since it is difficult to identify the predisposing factors in individual cases and to prevent the premature onset of labor, it is necessary to try to arrest such labor when it occurs. A theoretical scheme for the mechanism of labor in the human subject is presented. This permits the identification of four possible points of attack: (1) replacement of progesterone to reduce the myometrial sensitivity to oxytocin, (2) administration of beta-mimetic agents to relax the uterus and make it unresponsive to stimuli, (3) administration of ethanol to block oxytocin secretion, and (4) administration of anti-inflammatory drugs to inhibit prostaglandin synthesis. Results obtained with ritodrine, a beta-mimetic agent, and with ethanol are presented as illustration. Ritodrine gave somewhat better results than ethanol, possibly because the treatment was continued after discharge of the patients.
Am J Obstet Gynecol 1976 Dec 01
PMID:Prevention of prematurity. 1 89

Ritodrine hydrochloride was administered parenterally to pregnant ewes during spontaneous or oxytocin-induced uterine activity. The effects of ritodrine on the uterus and cardiovasculature were assessed both with and without simultaneous administration of either alpha or beta blockade. Ritodrine was found to be an effective inhibitor of both spontaneous and induced uterine activity. Ritodrine did cause maternal tachycardia but no significant hypotension. Alpha-adrenergic blockade did not influence the effects of ritodrine. Beta blockade with propranolol reversed the uterine and cardiovascular effects of ritodrine, whereas beta blockade with practolol reversed the cardiovascular effects without interfering with the inhibition of uterine activity produced by ritodrine.
Am J Obstet Gynecol 1976 Dec 15
PMID:Effect of ritodrine on uterine activity, heart rate, and blood pressure in the pregnant sheep: combined use of alpha or beta blockade. 1 90

The endopeptidase, post-proline cleaving enzyme, has been purified 10,500-fold in an overall yield of 18% from lamb kidney. The enzyme possesses a specific activity of 45 mumol/mg/min as tested with the substrate Z-Gly-Pro-Leu-Gly (Km = 6.0 X 10(-5)), has a molecular weight of 115,000, is comprised of two subunits with a molecular weight of 57,000, and exhibits maximal activity at pH 7.5 to 8.0. With the exception of the -Pro-Pro linkage, the -Pro-X-peptide bond (X equals L- and D-amino acid residues) located internally in the peptide sequence can be hydrolyzed (cleavage occurs faster when X = lipophilic side chain as compared to X = acidic side chain). The appropriate -Pro-X- bonds in zinc-free porcine insulin, oxytocin, arginine vasopressin, angiotensin II, bradykinin-potentiating factor were cleaved. Human gastrin, adrenocorticotropic hormone, denatured guinea pig skin collagen, and ascaris cuticle collagen were not degraded. Dipeptides with the structure Z-Pro-LD-X competitively inhibit post-proline cleaving enzyme.
J Biol Chem 1976 Dec 10
PMID:Post-proline cleaving enzyme. Purification of this endopeptidase by affinity chromatography. 1 73

The specificity of bovine spleen cathepsin B2 has been investigated by means of some natural oligo- and polypeptides, i.e. glucagon, melittin, insulin A and B chain, bradykinin, angiotensin I and II, oxytocin ACTH, clupein and salmin. The enzyme is primarily a carboxypeptidase which hydrolyzes peptide linkages of most amino acids common to proteins. In addition, cathepsin B2 displays amidase and esterase activity without requiring a free carboxyl group. The main pH optimum is between 4 and 5, in some cases higher.
Biochim Biophys Acta 1976 Dec 08
PMID:On the specificity of bovine spleen cathepsin B2. 1 11

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.
Mayo Clin Proc 1979 Dec
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.
Am J Physiol 1979 Dec
PMID:Influence of mucosal and serosal pH on antidiuretic action in frog urinary bladder. 4 16

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.
J Endocrinol 1979 Dec
PMID:Dopaminergic control of oxytocin release in lactating rats. 4 80

Immuno-enzyme histochemical investigations showed that, in the magnocellular hypothalamo-hypophysial neurosecretory system of the rat, vasopressin and oxytocin are synthetized in separate neurons. Both the vasopressin neurons and the oxytocin neurons are present in both the supraoptic and the paraventricular nuclei in about the same number. Preferential location of the two kinds of rat neurosecretory neurons is not as obvious as in the bovine hypothalamus. Their perikarya do not show distinct morphological differences. The two kinds of neurosecretory perikarya are the origin of separate vasopressin-containing and oxytocin-containing axons respectively. In the neural lobe, the distribution of the two different types of axons is described.
Cell Tissue Res 1975 Dec 02
PMID:Identification of the vasopressin producing and of the oxytocin producing neurons in the hypothalamic magnocellular neurosecretroy system of the rat. 5 2

The chief obstetrical problems encountered today in the prenatal evaluation of the high-risk fetus are presented. Advantages and pitfalls or recent techniques utilized in the management of the high-risk pregnancy are discussed. They include: a prenatal scoring system for identifying the high-risk population; examination of the karyotype of cells in amniotic fluid, and quantitation of alpha-fetoprotein levels in maternal plasma and amniotic fluid for the early prenatal detection of birth defects; ultrasonography for the intrauterine diagnosis of fetal growth retardation and assessment of fetal maturity; the use of maternal urinary estriol excretion, maternal plasma human placental lactogen levels and the oxytocin stress test for the early detection of fetal distress; estimation of fetal maturity by amniotic fluid analysis of lecithin or lecithin-sphingomyelin ratios, creatinine and Blue Nile fetal cell staining. Newer, still experimental, techniques (e.g., fatal breathing movements, fetoscopy, and dehydroepiandrosterone plasma clearance) are viewed in light of further possible decreases in maternal and perinatal mortality.
Environ Health Perspect 1976 Dec
PMID:Antepartum evaluation of the high-risk fetus: problems and prospects. 7 Dec 31

Intraamniotic urea and prostaglandin F2 alpha (PGF2a) combinations for midtrimester abortion were compared in the following series: 8 multiparas given 80 gm urea in 135 ml 5% dextrose and 5 mg PGF2a, 8 multiparas given urea only, 150 nulliparas and multiparas given urea and 5 mg PGF2a, and 180 given urea and 10 mg PGF2a. In the 2 small series, there was 1 failure in the urea group. Mean abortion times were 28.8 hours after urea, 18.3 hours after urea and 5 mg PGF2a, and 16.3 and 17.5 hours in the 2 large series given urea and 10 and 5 mg PGF2a, respectively. Urea caused loss of fetal heart tones within 2 hours, had a half-life in amniotic fluid of 3 hours, caused a low frequency of late emesis, and resulted in short-lived burning or warm sensation in 1 case of accidental intravascular injection. Oxytocin infusions were used frequently for failure to abort within 24 hours, or lack of uterine contractions after membrane rupture or incomplete abortion. PGF2a accelerated uterine tone, frequency, and integrated uterine pressure over the values measured in subjects given urea only.
Am J Obstet Gynecol 1977 Dec 01
PMID:Intra-amniotic urea and prostaglandin F2alpha for midtrimester abortion: clinical and laboratory evaluation. 7 92


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