Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An iodine-labelled derivative of beta-endorphin, 125I-Tyr27 beta h-endorphin, was used in carrier-free form to study the binding of beta-endorphin to brain opioid receptors. The experiments were carried out with rat cortex membranes in vitro under conditions that gave a high degree of naloxone reversible binding. Beta h-Endorphin and nonradioactive iodo-Tyr27 beta h-endorphin were found to be identical in their ability to inhibit the binding of 125I-Tyr27 beta h-endorphin. Competition experiments demonstrated the existence of binding sites with higher affinity for beta-endorphin than for a variety of other opioids, including naturally occurring fragments of beta-endorphin. The experiments show that 125I-Tyr27 beta-endorphin possesses similar binding properties to the unmodified peptide and can be used with the advantages of iodine-125 as an isotope for the investigation of beta-endorphin receptors in brain. In experiments employing 125I-Tyr27 beta-endorphin 1-27 as the radioiodinated ligand, binding curves were obtained which showed that beta-endorphin 1-31 was more potent than beta-endorphin 1-27 in inhibiting the binding of the labelled 27 residue peptide. With both the 27 and 31 residue radioligands, magnesium ion enhanced the specific binding whereas sodium ion and guanylyl-imidodiphosphate had a strong inhibitory effect. The data indicate that beta-endorphin 1-27 bindings with reduced affinity to the same receptors as beta-endorphin 1-31 and like the 31 residue peptide exhibits properties characteristic of an agonist.
 ...
PMID:Use of 125I-Tyr27 beta-endorphin for the study of beta-endorphin binding sites in rat cortex. 302 Apr 64

The responsiveness of lipolysis to the stimulatory agonists noradrenaline, corticotropin and glucagon and to the inhibitory agonists N6-phenylisopropyladenosine, prostaglandin E1 and nicotinic acid was investigated with rat white adipocytes incubated with a high concentration of adenosine deaminase (1 unit/ml). The cells were obtained from fed or 48 h-starved euthyroid animals or from fed or starved animals rendered hypothyroid by 4 weeks of treatment with low-iodine diet and propylthiouracil. Hypothyroidism increased sensitivity to and efficacy of all three inhibitory agonists in their opposition of noradrenaline-stimulated lipolysis. Starvation decreased sensitivity to all three inhibitory agonists when opposing basal lipolysis. Hypothyroidism decreased sensitivity to noradrenaline, glucagon and corticotropin by 37-, 4- and 4-fold respectively and decreased the maximum response to these agonists by approx. 50%, 50% and 75% respectively. Starvation reversed decreases in maximum response to these agonists in hypothyroidism. Starvation in the euthyroid state increased sensitivity to glucagon and noradrenaline, but did not alter sensitivity to corticotropin. Cells from hypothyroid rats were relatively insensitive to Bordetella pertussis toxin, which substantially increased basal lipolysis in the euthyroid state.
 ...
PMID:Sensitivity of adipocyte lipolysis to stimulatory and inhibitory agonists in hypothyroidism and starvation. 302 50

Potential therapeutic effects of combined oral contraceptives (COC) rigevidon and ovidon (estrogen:gestagen ratio of 1:5) were studied in 97 women aged 19-35 years. With respect to the anatomical state of the thyroid, the patients were divided into two groups: group 1 included 42 women with normal thyroid function and group 2 included 55 women with euthyroid hyperplasia of the thyroid gland of stage I-II (the anatomical state of the thyroid gland was ranked according to the five-point Swiss scale adopted by WHO in 1975). All patients had a history of pregnancy, normal delivery, or abortion. The state of the pituitary-thyroid system was estimated by absorption of iodine isotopes in the thyroid tissue, and by the blood levels of thyrotropic hormone, thyroxine-binding globulin, thyroxine, and triiodothyronine. Activity of the pituitary- adrenal system was estimated by the blood levels of adrenocorticotropic hormone (ACTH) and cortisol. Blood samples were withdrawn 9 and 10 hours prior to the onset of COC administration, and after 24 and 48 weeks of COC use. The changes in the functional state of the pituitary- thyroid system in groups 1 and 2 were identical throughout the entire period of COC administration. Progressive increase in the levels of thyroxine and triiodothyronine was associated with inhibition of the thyrotropic function of the pituitary seen as decrease in thyrotropin levels. COC administration caused decrease in size of hyperplastic tyroid gland. Prior to COC administration, women in group 2 showed significant elevation of ACTH levels and marked decrease in ACTH levels and increase in cortisol levels in both groups. Normalization of the size of thyroid gland indicated that COC be used therapeutically in patients with thyroid hyperplasia.
 ...
PMID:[Effect of combined oral contraceptives on the hypophyseo-thyroid and hypophyseo-adrenal systems in women with various anatomy of the thyroid gland]. 323 85

A simple technique for determination of the molecular (Stokes) radius of radioiodinated proteins was developed using the same column and chromatographic conditions employed in routine radioimmunoassay tracer purification. The calibration curve for five radioiodinated standard proteins presented a highly significant correlation (r = -0.996; P less than 0.001) and allowed precise molecular radius determination for labeled human growth hormone (hGH), luteotropin (hLH), follicle-stimulating hormone (hFSH), thyrotropin (hTSH), prolactin (hPRL), and corticotropin (hACTH), enabling detection of differences of the order of +/- 3%. The validity of the method was verified by determining the molecular radius of hGH in both "cold" (unlabeled standards and unknowns) and "hot" (radioiodinated standards and unknowns) systems. The technique can be applied in a very simple manner, requiring just one simple additional calibration run before Sephadex G-100 tracer purification. Furthermore, it can be applied to any protein, even when only extremely limited amounts are available. Since the standards and unknowns are labeled and chromatographed under identical conditions, potential common alterations of the molecule due to oxidation, iodine incorporation, tracer-carrier interactions, etc., are automatically corrected for.
 ...
PMID:Stokes radius determination of radioiodinated polypeptide hormones by gel filtration. 323 67

A newly devised dual labeled iodine isotopic method is described for the detection and quantitation of alterations in thyroxine (T(4)) deiodination rate in man. This method employs the principle of a constant (125)I infusion to serve as a reference source for the generation of (131)I derived from the deiodination of T(4)-(131)I. Measurement of these two iodide isotopes are made in serially timed urine collections and are expressed in terms of a ratio value. Using this technique, it was possible to measure accurately the effects of a single dose of 6-propylthiouracil (6-PTU) in producing inhibition of T(4) deiodination in euthyroid subjects. It was also possible to assess the time of onset, duration of action, and degree of inhibition produced by 6-PTU. Employing single doses of 6-PTU, ranging from 100 to 1000 mg, there was found to be a log dose relationship with a degree of inhibition observed in T(4) deiodination. In control studies T(4) deiodination rate was found to be constant for periods ranging up to 72 hr in normal ambulating subjects. The acute administration of many other agents was employed in an attempt to alter the T(4) deiodination rate. These included diphenylhydantoin, methimazole, triiodothyronine, thyroxine, thyroid stimulating hormone (TSH), adrenocorticotropin (ACTH), hydrocortisone, predinsolone, potassium iodide, epinephrine, and oxytocin. No detectable change in T(4) deiodination rate was observed with these agents in the dosage ranges employed in this study. The lack of any observable alteration in the T(4) deiodination rate in response to this array of drugs and hormones appears to indicate that the availability of T(4) to intracellular sites of deiodination and possibly action is well modulated to resist abrupt changes.
 ...
PMID:A new method for the measurement of acute alterations in thyroxine deiodination rate in man. 431 46

Biologically active iodine-125-labeled adrenocorticotropic hormone (ACTH) binds specifically to ACTH receptors extracted from adrenals. Unlabeled ACTH at 1 picogram per milliliter significantly displaces labeled ACTH from these receptors. This system, which appears to be applicable to all polypeptide hormones, provides a rapid and sensitive method for measurements of biologically active ACTH in dilute whole plasma.
 ...
PMID:Radioreceptor assay of adrenocorticotropic hormone: new approach to assay of polypeptide hormones in plasma. 431 88

Precise local injections of propidium iodide (PI) were made, using an iontophoretic technique, into various regions of the globus pallidus (GP) of rats. The locations of the injection sites and the position of retrogradely labelled caudate putamen (CP) cell bodies demonstrated a topographic arrangement of efferents from the CP projecting to the pallidum. The PI labelled cell bodies in the CP were also counterstained for met-enkephalin immunofluorescence. Cell bodies labelled with PI, which showed co-existing enkephalin immunofluorescence, were found in CP projections to the pallidum.
 ...
PMID:Microiontophoretic injection of fluorescent tracer combined with simultaneous immunofluorescent histochemistry for the demonstration of efferents from the caudate-putamen projecting to the globus pallidus. 618 3

Corticotropin releasing factor (CRF) has recently been identified, purified and shown to be a 41-amino acid polypeptide that stimulates secretion of beta-endorphin and ACTH. The metabolic clearance rates (MCR) of I125-CRF and I125-TyroCRF were measured in cynomologus monkeys using the pulse injection and the continuous infusion methods. Hunter-Bolton reagent was used for iodination of CRF and the chloramine-T method for Tyro-CRF. Gel chromatography was used to separate free iodine (and radioiodinated small fragments) from iodinated CRF in plasma samples. Disappearance of I125-CRF or I125-Tyro-CRF could be modeled with two components (bi-exponential). Plasma half-life of I125-CRF was 17.1 +/- 2.44 min (mean +/- SE, n=4) for the fast component and 198 +/- 5.3 min for the slow component. The MCR of I125-CRF using the pulse injection technique was 0.44 +/- 0.06 L/Kg/d, n=4 and the volume of distribution 213.5 +/- 12 ml, n=4, roughly equal to the plasma volume. Continuous infusion of I125-CRF and of I125-Tyro-CRF gave MCR's ranging between 2.23 -= 5.08 L/Kg/d, n=4. I125-ACTH MCR, measured for comparison using the same technique, was 5-10 fold higher. Thus, the plasma half-life of CRF is longer than for all other known hypothalamic peptides and its metabolic clearance rate relatively low and considerably less all other known hypothalamic peptides and its metabolic clearance rate relatively low and considerably less than that of ACTH. Strong binding of CRF to plasma proteins may be responsible for the small volume of distribution and lower MCR values for the pulse injection method.
 ...
PMID:Metabolic clearance rate and plasma half-life of radioiodinated corticotropin releasing factor in a primate. 628 52

Intracerebroventricular administration of all three prototype non-peptide opioid receptor (mu, kappa and sigma) agonists, morphine, ketocyclazocine and N-allyl-normetazocine (SKF 10,047) induced hyperthermia in rabbits. Similar administration of peptide opioids like beta-endorphin (BE), methionine-enkephalin (ME) and its synthetic analogue D-ala2-methionine-enkephalinamide (DAME) also caused hyperthermia. As expected, the synthetic enkephalin DAME was more potent than the parent enkephalin. Of the three anion transport systems (iodide, hippurate and liver-like or L) present in the choroid plexus, it is suggested that only the L transport system seems to be important to ventricular inactivation of BE and DAME since iodipamide (an inhibitor of the L transport system) augmented the hyperthermia produced by BE and DAME. Prostaglandins (PG) and norepinephrine (NE) were not involved in peptide and non-peptide opioid-induced hyperthermia because a PG synthesis inhibitor, indomethacin, and an alpha-adrenergic receptor blocker, phenoxybenzamine, had no thermolytic effect on them. Likewise cAMP was not required since a phosphodiesterase inhibitor, theophylline, did not accentuate the hyperthermia due to peptide and non-peptide opioids. Naloxone-sensitive receptors were involved in the induction of hyperthermia by morphine. BE, ME and DAME since naloxone attentuated them. In contrast, the hyperthermic response to ketocyclazocine and SKF 10,047 were not antagonized by naloxone.
 ...
PMID:Peptide and non-peptide opioid-induced hyperthermia in rabbits. 630 8

We have studied the behaviour of 125I-labelled alpha-MSH under different experimental conditions. Until now, the chloramine T method had been used by most investigators with variable results. We have tested three other labelling techniques based on 125I mild oxidation: (1) an enzymatic method with lactoperoxidase, (2) a sparingly soluble chloramine method (T.D.G.U.) and (3) modified chloramine T procedure, 'the iodine volatilization method'. Labelled hormone obtained after each kind of iodination was assayed for immunoreactivity. In addition, time course degradation was measured by classical RIA incubation procedures. Charcoal-dextran was used to separate bound and free antigen. We have found chloramine T-iodinated alpha-MSH to be significantly more damaged than preparations obtained by other methods and to be less stable when stored at -18 degrees C. No differences were found between the differently labelled 125I-labelled alpha-MSH fresh preparations in binding to surface receptors of human melanoma cell lines in culture.
 ...
PMID:Comparison and evaluation of different methods for alpha-MSH labelling. 675 23


<< Previous 1 2 3 4 5 Next >>