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

The neurophysins are the carriers of oxytocin and antidiuretic hormone (ADH) along the hypothalamo-neurohypophyseal tract. They are liberated when the hormones are released; their radioimmunoassay which are methodologically more simple than that of the active nonapeptides can be used in clinical practice. Moreover, the separate assay of each major neurophysins bring a specific index of the release of each hormone. The radioimmunoassay for circulating neurophysins appears to be useful for the differential diagnosis of polyuria, water retention and hypothalamic disease. The neurophysins are however devoided of any antidiuretic or oxytocic properties and their half-lives differ slightly from that of circulating hormones: therefore a basal level or values obtained in the course of an inhibitory test must be cautiously interpreted.
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PMID:[The neurophysins (author's transl)]. 73 18

Impaired excretion of a water load is known to occur in adrenal insufficiency and to be corrected by administration of glucocorticoid. Such impairment has been related to either a loss of a permissive effect of glucocorticoids on the diluting segments of the nephron or to an alteration of release, turnover, or action of antidiuretic hormone. Specific and sensitive RIAs for arginine vasopressin and neurophysin were utilized to measure plasma and pituitary levels of neurohypophyseal peptides at baseline and after an intragastrically administered water load. Conscious, unanesthetized, and nonstressed sham-operated, adrenalectomized, and adrenalectomized prednisone-treated rats were studied. The results demonstrate a significant elevation in vasopressin and neurophysin in plasma in adrenalectomized rats maintained in a normal state of hydration. After water loading, the adrenalectomized rats diluted their plasma osmolality but had a decreased urinary volume, increased urinary osmolality, and elevated vasopressin and neurophysin in their plasma. In the pituitary, vasopressin and neurophysin were depleted in adrenalectomized rats, indicating increased secretion of these peptides. It is concluded that elevated vasopressin in plasma may be an important factor in the incomplete water diuresis in adrenal insufficiency.
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PMID:Plasma neurophysin and vasopressin in the rat: response to adrenalectomy and steroid replacement. 74 29

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

Four cases of water intoxication in connection with oxytocin administration during saline-induced abortions are described. The mechanism of water intoxication is discussed in regard to these cases. Oxytocin administration during midtrimester-induced abortions is advocated only if it can be carried out under careful observations of an alert nursing staff, aware of the symptoms of water intoxication and instructed to watch the diuresis and report such early signs of the syndrome as asthenia, muscular irritability, or headaches. The oxytocin should be given only in Ringers lactate or, alternately, in Ringers lactate and a 5 per cent dextrose and water solutions. The urinary output should be monitored and the oxytocin administration discontinued and the serum electrolytes checked if the urinary output decreases. The oxytocin should not be administered in excess of 36 hours. If the patient has not aborted by then the oxytocin should be discontinued for 10 to 12 hours in order to perform electrolyte determinations and correct any electrolyte imbalance.
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PMID:Water intoxication associated with oxytocin administration during saline-induced abortion. 80 83

A method for the preparation of N-maleoylamino acids and esters is reported. These compounds were shown to inhibit both the oxytocin-induced smooth muscle contraction in the isolated rat uterus and the vasopressin-induced water loss from the isolated toad bladder. The inhibitory ability of the maleimides in the toad bladder assay was found to be related to their corresponding partition coefficients by the equation: log 1/C = -0.055 (log P) 2 + 0.227 log P + 3.96. N-Maleoylamino acids can be coupled to peptides to form alkylating reagents which react rapidly with sulfhydryl groups. The synthesis of [1-(N-maleoylglycyl)cysteinyl]oxytocin (3) and [1=(N-maleoyl-11-aminoundecanoyl)cysteinyl]oxytocin (4) as potential affinity labeling reagents is described. These oxytocin analogs were shown to readily react with sulfhydryl-containing compounds; however, neither 3 nor 4 was seen to inhibit in the rat uterus assay at concentrations up to 3 times 10(-5)M. When tested on the mucosal and serosal surfaces of the toad bladder, assay inhibition was seen only on the mucosal surface. These results are discussed with respect to the possible existence of sulfhydryl groups at neurohypophyseal receptors.
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PMID:Alkylating derivatives of amino acids and peptides. Synthesis of N-maleoylamino acids, [1-(N-maleoylglycyl)cysteinyl]oxytocin. Effects on vasopressin-stimulated water loss from isolated toad bladder. 80 6

Extracellularly recorded action potentials were obtained from hypothalamic supraoptic neurones in unanaesthetized rhesus monkeys. Rates and patterns of firing were studied during an initial control period, during 5 successive days of water deprivation and during 4 further days when drinking water was again available. During water deprivation, plasma osmolarity increased progressively from about 300 mOsmoles/kg to about 340 mOsmoles/kg; control values were again reached after 3 days of rehydration. Systematic changes in action potential firing accompanied the changes in plasma osmolarity. Under control conditions, the majority of cells fire slowly and irregularly (type i), whilst a few cells exhibited phases of alternating activity and silence (type p). As dehydration progresses, the frequency of neuronal firing increase and the pattern of firing changes. By the third day the majority of cells are type p with few type i cells being found. By the fourth day, the population consists of type p cells with some others showing a high continuous rate of firing (type c). By the fifth day, these two cell types are found in approximately equal proportions. Rehydration of the animal reverses the situation. We propose that type i cells contribute little, if at all, to hormone secretion, while type p and type c cells would be in a more actively secreting state. According to this view, the three firing patterns would represent different activity states of the same functional population stimulated by the unspecific stimulus of water deprivation rather than functionally different neurones. However, the use of stimuli which selectively release either oxytocin or vasopressin may be needed to answer this problem.
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PMID:Hypothalamic supraoptic neurones: rates and patterns of action potential firing during water deprivation in the unanaesthetized monkey. 81 25

When Rana cancrivora were collected from fresh water and dehydrated (weight loss 4-10%) by exposure to saline, the plasma titre of hydro-osmotic activity, measured by amphibian bladder assay, was increased three-to fourfold. This activity, which was abolished by thioglycollate and by incubation with tyrosinase or trypsin, was ascribed to vasotocin. The plasma vasotocin activities (hydrated and dehydrated frogs respectively) were estimated to be 0-03-0-5 and 0-15-0-25 mug/1; if referred to oxytocin as a standard the equivalent values were 10 and 30-60 mu./ml. Assuming that the increase represented released pituitary hormone, the amount of vasotocin released by osmotic dehydration was calculated to be of the order of 1 ng. Pituitary glands of hydrated and dehydrated frogs were estimated to have 0.15 and 0-18 mug vasotocin/gland respectively. The possible physiological function of released vasotocin in promoting reabsorption of urea from the urinary bladder is discussed in relation to the euryhaline ability of R. cancrivora.
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PMID:Vasotocin-like activity in the plasms of the euryhaline frog (Rana cancrivora) after transfer from fresh water to saline. 81 47

Using a new antiserum, an enzymatic radioiodination of arginine vasopressin (AVP), and the methodology of Robertson et al. (1,2), we have developed a sensitive and specific radioimmunoassay for plasma AVP in the monkey. The sensitivity of the assay is 0.5 muU/ml, the cross reaction with oxytocin (OT), minimal. We used this assay to study the effects that variations in blood osmolality have in regulating AVP secretion in unanesthetized, chair-restrained, chamber-isolated, adult female rhesus monkeys. Under water ad lib conditions, plasma AVP and osmolality were relatively constant, averaging 1.7 +/- 0.6 (SD) muU/ml and 298 +/- 3 mosmol/kg, respectively. Water loading decreased plasma AVP and osmolality to 0.6 +/- 0.2 muU/ml and 282 +/- 6 mosmol/kg, respectively. When fluid restriction increased osmolality, plasma AVP rose progressively to twice the baseline after 1 day, and to 6 times the baseline after 3 days. The rise in plasma AVP was linearly correlated with the rise in osmolality (r = 0.93; P less than 0.001). Intravenous infusions of hypertonic saline produced significant rises in plasma osmolality and plasma AVP. There was a dose-related rise in plasma AVP that declined later at the expected rate with the infusion of physiological amounts of synthetic AVP.
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PMID:Radioimmunoassay of arginine vasopressin in Rhesus monkey plasma. 81 49

By means of an experimental i.v. and i.m. oxytocin administration the quantitative relation between the amount of oxytocin and the quantity of ejected milk in goats was confirmed. With increasing oxytocin doses the latency period after the i.v. administration shortened, from 0.33 min. after 50 mU to 0.21 min. following 1000 mU. After the 2000 mU dose the latency period did not substantially change any more (0.18 min). The situation was nevertheless different after the i.m. oxytocin administration. No ejection followed after the 50 mU dose. Beginning with the 500 mU dose the latency period shortened, from 2.91 min. to 1.30 min. after the 2000 mU dose. With both administration manners the ejection time was prolonged up to the 1000 mU dose, then it did not substantially change. Similarly also the amount of ejected milk increased with the two administration methods up to 1000 mU, amounting to 20.6% after the i.v. and to 17.9% after i.m. administration. After 2000 mU the amount of milk ejected failed to substantially change, amounting to 19.4% with both administration manners. In experiments with manual udder stimulation with respect to feeding, the stimuli during feeding were found to influence the course of the milk ejection reflex. As compared with the pre-feeding experiments, the latency period after feeding was prolonged from 0.83 min. to 1.49 min; the amount of alveolar milk expressed in per cent of the total milk yield obtained decreased from 18.9 to 7.9%, and the ejection time shortened from 2.29 to 0.70 min. In the study the effect of various feeds on the alveolar milk ejection was also followed. Water administration did not call forth dropping off of the milk. Feeding hay called forth the ejection of 2.5% of alveolar milk occurring after an 0.25 min. latency period. Pollard provoked the ejection of 3% and the ejection time shortened from 2.29 toats (20%) can at least partially be ascribed to milk release during food intake.
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PMID:[Milk ejection in goats and its influencing by feed]. 82 45

Midtrimester abortions were induced in 295 patients with a combination of intra-amniotic urea and intravenous oxytocin. The mean injection-abortion interval was 26.4 hours. Abortion occurred spontaneously within 50 hours of amnioinfusion in 257 patients. The macerating effect of the hypertonic urea on fetal tissues allowed easy termination of the remaining 38 pregnancies by suction curettage at 50 hours after injection. Decreased urinary output occurred during the oxytocin infusions, but water intoxication was prevented by close monitoring of urinary output and serum electrolytes, and by the use of a concentrated solution of oxytocin in normal saline, allowing the administration of small volumes.
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PMID:Induction of midtrimester abortion with intra-amniotic urea and intravenous oxytocin. 83 17


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