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

Experimental conditions and parameters involved in high performance liquid chromatography (HPLC) separations of the peptide hormone oxytocin and seven of its diastereoisomers, namely [1-hemi-D-cystine]-, [2-D-tyrosine]-, [4-D-glutamine]-, [5-D-asparagine]-, [6-hemi-D-cystine-], [7-D-proline]-, and [8-D-leucine]-oxytocin, on reverse phase columns were investigated. The effects of solvent, pH, and salt concentration were studied. Using the solvent systems 10% tetrahydrofuran-ammonium acetate buffer or 18% acetonitrile-ammonium acetate buffer and the muBondapak C18 support, oxytocin was separated from each of its diastereoisomers under all conditions studied, but the order of elution of diastereoisomers was highly dependent on solvent and to a lesser extent on pH. Separations of the hormone and its diastereoisomers on reverse phase HPLC and on classical partition chromatography on Sephadex G-25 were compared. The results are discussed in terms of the interactions of the solute with the reverse phase column and the solvent system. Implications of these findings in terms of the different solution conformations of the peptides are discussed.
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PMID:The separation of peptide hormone diastereoisomers by reverse phase high pressure liquid chromatography. Factors affecting separation of oxytocin and its diastereoisomers--structural implications. 3 28

Analysis of the 220 MHz proton magnetic resonance spectra of bovine neurophysins-I and -II and of the effects of pH and succinylation of these spectra has allowed identification of the -CH3 proton resonances of the amino-terminal alanine of both proteins and of the -CH3 resonances of methionine-2 of neurophysin-II. The alanine -CH3 resonance of neurophysin-I is a sharp doublet at all pH values between 1 and 10.5 indicating relatively few restrictions on its mobility. By contrast, the -CH3 resonances of the amino-terminal alanine and methionine-2 of neurophysin-II undergo pH-dependent changes in broadening compatible with the formation of an intramolecular salt-bridge at neutral pH between the protonated alpha-amino and an unprotonated side chain carboxyl. The results suggest that differeces in the properties of the two proteins are partially mediated by conformational differences involving their amino-terminal sequences. The potential usefulness of the amino-terminal resonances as n.m.r. 'reporter' signals is additionally demonstrated by studies of the effects of spin labels on the neurophysin-I amino-terminal alanine resonance; these studies place the amino-terminus of neurophysin-I approximately 14 A from residue 3 of peptides bound to the strong neurophysin hormone-binding site.
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PMID:Identification and observation of alkyl proton resonances of the amino-terminal residues of bovine neurophysins. Evidence for conformational differences between neurophysin-I and neurophysin-II. 3 30

The specifically 13C-labeled (90% 13C-enriched) peptide hormone derivatives [1-hem[2-13C]cystine]oxytocin, [1-hemi[1-13C]cystine]oxytocin, and [2-[-2-13C]tyrosine[-oxytocin and the analogue [3-[2-13C]leucine]oxytocin were prepared by total synthesis and used to study the interactions of the neurohypophyseal hormones with the bovine neurophysins as a function of pH and temperature. Under all conditions, whether high or low pH, the chemical shifts of the labeled carbon atoms of the bound hormones are the same, but they are shifted significantly from their positions in the free hormone. These results indicate that interactions of the side chain and disulfide moieties of the hormone with the neurophysins do not change as a function of pH. At neutral pH and 20--35 degrees C, the labeled atoms of the hormone are in slow exchange (1--5 s-1) with the neurophysins for the above hormone derivatives, but at low pH they are in intermediate or fast exchange depending upon the pH and temperature. At low pH, the dissociation rate constant (koff) is about 100-fold greater than the value at neutral pH, and this increase appears to be due exclusively to the breaking of the salt bridge involving the N-terminal amino group of oxytocin and a side-chain carboxyl group of neurophysin. Since the dissociation constant (Kd) also increases by about 100-fold in going from neutral to low pH, the association rate constant is deduced to be the same at neutral and low pH. In contrast to the low pH results, an increase in pH (from 6.6 to 10.5) leads to a continual decrease in the binding constant but to no apparent change in the dissociation rate constant. The bound hormone is always in slow exchange at high pH, even when the binding constant has been reduced by 2 or 3 orders of magnitude. At high pH, the decrease in binding affinity is due solely to the deprotonation of the alpha-amino group of the free hormone. Thus, at high pH the apparent association rate constant decreases, while the dissociation rate constant remains unchanged.
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PMID:Investigation of the interactions of oxytocin with neurophysins at low pH using carbon-13 nuclear magnetic resonance and carbon-13-labeled hormones. 3 33

Neurohypophysial hormone-Neurophysin complexes have been prepared from posterior pituitary glands of Artiodactyla (ox, sheep, pig), Perissodactyla (horse) and Cetacea (whale), by fractionated salt precipitation. The components have been separated by molecular sieving in 0.2 M acetic acid and neurophysins have been purified by ion-exchange chromatography on DEAE-Sephadex A-50. Two types of neurophysins, MSEL-neurophysins and VLDV-neurophysins, can be distinguished according to the amino acid residues in positions 2, 3, 6 and 7. MSEL-neurophysins of sheep, ox and pig have been characterized by the amino acid sequence. Ovine and bovine MSEL-neurophysins are nearly identical (one substitution out of 95 residues) and porcine MSEL-neurophysin is very similar (four substitutions and an apparent 3-residue C-terminal deletion). The biological function of neurophysins might be the carriage of neurohypophysial hormones but in this respect, each type of neurophysin is not clearly specific for a given hormone. On the other hand, each neurophysin might share a common precursor with a neurohypophysial hormone, the two parts remaining associated after cleavage. However, in the sheep posterior pituitary gland, the molar proportions of the two types of neurophysins, oxytocin and arginine vasopressin, are not equal, MSEL-neurophysin being more abundant than the other components. If a common precursor exists, neurophysins and neurohypophysial hormones are not merely produced by a simple cleavage mechanism.
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PMID:[Neurophysins of Mammals: evolution and biological signification]. 13 92

Rh-sensitization in cases of spontaneous and induced abortions is discussed. In an intact pregnancy, the average volume of fetomaternal transfusion is about .1-.2 ml. Rh antibodies occur in 2% of the cases of Rh-negative mother with Rh-positive child during the first pregnancy and 11-17% during the second pregnancy. The standard Anti-D dosage in such cases is 250-330 mcg, enough to counteract a fetomaternal transfusion of 30 ml. In the case of spontaneous abortions, the average volume of fetomaternal transfusion ranges from .l-1.0 ml. Fetal erythrocytes are found in 5-25% of pregnant women before the 12th week of pregnancy and 12-45% after the 12th week. The risk of Rh-sensitization ranges from 3-10% in cases of spontaneous abortion; the risk increases with the length of pregnancy. Other factors, e.g., parity, age, and the use of oxytocin during subsequent curettage, show no relationship to the volume of fetomaternal transfusion. In the case of induced abortion, the volume of fetomaternal transfusion is generally greater than .1 ml. Fetomaternal transfusions were more frequent in conjunction with salt water instillation than with vacuum aspiration in pregnancies before the 12th-16th week of pregnancy; the opposite was true for induced abortions performed after the 13th week of pregnancy. Fetomaternal transfusion is also possible in cases of ectopic pregnancy and hydatidiform mole. Anti-D prophylaxis should be used in all cases of spontaneous and induced abortion, ectopic pregnancy, and hydatidiform mole, except in cases before the 6th week of pregnancy. The standard dosage of 250-330 mg should be used, except before the 12th week of pregnancy; in this case, 50 mcg has been shown to be sufficient.
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PMID:[Anti-D prophylaxis after abortions and interruptions]. 21 9

Prostaglandin F2alpha (PGF2alpha) was administered extraamniotically for pregnancy termination in 15 cases of intrauterine fetal death between 18-39 weeks gestation and in 10 cases of fetal abnormality or hydatidiform mole between 16-28 weeks gestation. After thorough cleansing of the cervix a No. 16 Foley catheter was inserted and retained in the extraamniotic space by means of the balloon, inflated with 10 ml of saline. PGF2alpha tromethamine salt (Prostin F2alpha, Upjohn Netherland, was diluted to an aqueous solution of 0.25 mg PGF2alpha/ml and administered via the catheter at 1 hour intervals. Treatment was started with 0.5 mg (2 ml) and the initial dosage was increased by increments of 0.25 mg to a maximum of 1 mg/hour if uterine contractility did not ensue. Temperature, pulse rate, and blood pressure were checked regularly. Antibiotherapy (ampicillin) was routinely given at the beginning of the study but later abandoned. Pethidine was used as an analgesic whenever required. Abortion or delivery was achieved in all 25 cases studied. In all but 1 of the patients with intrauterine fetal death, delivery occurred within 24 hours and the placenta was delivered spontaneously and complete in 11 of the 15 patients (73%). There was no relationship between the duration of fetal death and induction delivery interval. In cases with an abnormal but living fetus or hydatidiform mole, abortion was frequently incomplete and the mean induction abortion interval (24.4 hours) was 10 hours longer than that observed in cases of intrauterine fetal death (14.5 hours). 5 of the 10 patients required intravenous oxytocin from a cervical dilatation of 3-6 cm onwards and from 14-30 hours after the start of PGF2alpha administration. In these cases abortion always followed within 3 hours of starting the oxytocin infusion. Side effects were moderate in both groups of patients and pyrexia of 38 degrees Centigrade or more was never encountered. None of the patients showed any signs of intrauterine infection. Blood loss exceeded 500 ml in 4 of the 25 patients studied (16%), but only 1 patient, with a molar pregnancy, lost as much as 1000 ml. Discontinuous extraamniotic prostaglandin therapy constitutes a safe and effective approach for the active management of intrauterine fetal death.
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PMID:Extraamniotic prostaglandin F2 alpha for intrauterine death and fetal abnormality. 29 60

Arginine vasotocin, arginine vasopressin, and oxytocin play a critical role in the stimulation of labor and delivery and in salt and water homeostasis in the newborn infant. The authors present information on their chemistry, secretion, and metabolism, and discuss the clinical effects upon target organs of their presence or absence.
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PMID:Development pharmacokinetics of the posterior pituitary hormones. 38 65

Oxytocin (OT) was synthesized employing the solid phase method. Resins made of copolymers of polystyrene-1%-crosslinked with divinylbenzene gave better yields (73-95%) of Z-Cys(Bzl)-Tyr(Bzl)-Ile-Gln-Asn-Cys(Bzl)-Pro-Leu-Gly-NH2 (I) than 2%-crosslinked resins (10--56%). Reduction of I with Na-liq.NH3 and oxidation with I2-MeOH at -40 degrees minimized dimer and polymer formation, and resulted in good yields (49--54%) of OT. The large volumes of MeOH required when several grams of I are reduced and then oxidized were rapidly evaporated in vacuo, and the residue was desalted by dissolving the peptide in a small volume of glacial acetic acid and filtering to remove the salt. OT was purified by adsorption chromatography on a silica gel column with combinations of MeOH-CHCl3 of graded polarity. Oxytocin elutes with 33% MeOH-CHCl3. After two purification steps by adsorption chromatography, the resulting OT was found to be homogeneous. The hormone was characterized chemically and found to be active biologically.
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PMID:Synthesis of oxytocin using iodine for oxidative cyclization and silica gel adsorption chromatography for purification. 42 90

Medicaments are used to prepare for instrument abortions in the 1st trimester and as inducers of abortion in the 2nd trimester. The effects, side effects, and dangers depend on the substances used and the route of application, which can be vaginal, cervical, injection, instillation, extraamniotic, intraamniotic, intravenous, or intramuscular. In the past, intraamniotic instillation of a 20% salt solution was the most common 2nd trimester method in Japan, the US, and Eastern Europe, giving a success rate of 90%. Serious side effects prompted substitution of extraamniotic instillation, which rarely produces serious side effects. Instillation of a 60% urea solution into the amniotic fluid in combination with oxytocin or prostaglandin produces an abortion in 13-21 hours, with a failure rate of 3% and a frequency of cervical laceration of under 1%. Extraamniotic use of a .1% solution of rivanol yields a success rate of about 85%, with a relatively long average time to explusion of 24-41 hours. In case of failure the procedure can be repeated. The advantage of the Rivanol method is the rarity of infectious complications. Alcohol is not used as a human abortifacient because it produces necrosis in the decidua and placenta. Prostaglandins are used in most 2nd trimester abortions. Research is underway to identify derivatives that will have an extended uterine impact without serious side effects. Different routes of administration have different effectiveness rates and dangers. All prostaglandins cause side effects including pain during uterine contractions, gastro-intestinal reactions, nausea, vomiting, fever, and headaches. Specific preparations are associated with other effects, some of them life-threatening. Emergency treatment should be available when these substances are used. Adjuvant measures may be employed before adminstration of an abortifacient agent to soften the cervix, or after administration to hasten the procedure. The choice of procedure depends upon the personality, health, and other characteristics of the woman and the experience of the doctor and the clinic.
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PMID:[Chemical methods of abortion]. 48 68

1. Bovine neurophysins were prepared by a modified method, in which a Biogel P-60 column was used. This yielded two neurophysin fractions, the first containing neurophysin I and small quantities of the other neurophysins,the second containing neurophysin II and C, and only traces of neurophysin I. 2. Antibodies against neurophysin I, II and C were prepared by an original method, 5 mug in 100 mul water of each of the two fractions were applied on a gel slab and separated by iso-electric focusing in a pH gradient 4--6. The separated bands were visualized with 8-aniline-1-naphthalene sulfonic acid, magnesium salt and strips respectively containing neurophysin I, II or C were cut out. The neurophysin-containing strips were homogenized in complete Freund's adjuvant and injected into rabbits. 3. The specificity of the antisera were tested by immunocytochemistry and by radioimmunoassay. By this latter method, it was determined that cross-reactivity was less than 1%. The cross-reaction, observed with the immunohistochemical method could be eliminated by differential absorption. 4. It was found that neurophysin C antisera were undistinguishable from the neurophysin II antisera, while showing little cross-reactivity with the neurophysin I antisera. This suggests that in vivo neurophysin C is not a real neurophysin, or at least, that it is very similar to neurophysin II. 5. Highly purified bovic focusing method. By modifying a LKB Uniphor electrophoresis apparatus, the elute the proteins without switching off the voltage. The resolution of the technique is close to that offered by analytical gel iso-electric focusing.
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PMID:Bovine neurophysins I, II and C: new methods for their purification and for the production of specific antibodies. 79 44


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