Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To elucidate the regulation of secretion of beta-endorphin in Nelson's syndrome, both ACTH and beta-endorphin were measured using RIA. We found that beta-endorphin and ACTH were secreted concomitantly in responses to the administration of lysine-8-vasopressin and TRH. Conversely, the administration of somatostatin to this patient reduced the secretion of both beta-endorphin and ACTH. Thus, beta-endorphin is probably secreted cooredinately with ACTH in patients with Nelson's syndrome.
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PMID:Plasma beta-endorphin responses to somatostatin, thyrotropin-releasing hormone, or vasopressin in Nelson's syndrome. 624 30

Growth hormone (GH)-releasing activity has been detected in extracts of carcinoid and pancreatic islet tumors from three patients with GH-secreting pituitary tumors and acromegaly. Bioactivity was demonstrated in 2 N acetic acid extracts of the tumors using dispersed rat adenohypophyseal cells in primary monolayer culture and a rat anterior pituitary perifusion system. The GH-releasing effect was dose responsive and the greatest activity was present in the pancreatic islet tumor. Small amounts of activity were also found in two other tumors (carcinoid and small cell carcinoma of lung) unassociated with GH hypersecretion. Each of the tumors contained somatostatin-like immunoreactivity but the levels did not correlate with the net biologic expression of the tumor. Sephadex G-75 gel filtration indicated the GH-releasing activity to have an apparent molecular size of slightly greater than 6,000 daltons. The GH-releasing activity was adsorbed onto DEAE-cellulose at neutral pH and low ionic strength, from which it could be eluted by increasing ionic strength. The GH-releasing activity was further purified by high pressure liquid chromatography using an acetonitrile gradient on a cyanopropyl column to yield a preparation that was active at 40 ng protein/ml. Partially purified GH-releasing activity, from which most of the bioactive somatostatin had been removed, increased GH release by pituitary monolayer cultures to five times base line. Enzymatic hydrolysis studies revealed that the GH-releasing activity was resistant to carboxypeptidase, leucine-aminopeptidase, and pyroglutamate-amino-peptidase but was destroyed by trypsin and chymotrypsin, indicating that internal lysine and/or arginine and aromatic amino acid residues are required for biologic activity and that the NH2-terminus and CO9H-terminus are either blocked or not essential. The results provide an explanation for the presence of GH-secreting tumors in some patients with the multiple endocrine neoplasia syndrome, type I, and warrant the addition of GH-releasing activity to the growing list of hormones secreted by tumors of amine precursor uptake and decarboxylation cell types.
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PMID:Partial purification and characterization of a peptide with growth hormone-releasing activity from extrapituitary tumors in patients with acromegaly. 624 40

ACTH excretion by cultured nonenzymatically dispersed pituitary tumor cells from a patient with Nelson's syndrome was studied. Hormone release was suppressed by 74 +/- 6% by the addition of 1 microM of the met-enkephalin analog FK 33824, while naloxone (1 microM) stimulated ACTH release by 70 +/- 5%. Somatostatin, dexamethasone, bromocriptine, and cyproheptadine in a concentration of 1 microM each inhibited ACTH release by 25 +/- 2%, 35 +/- 2%, 52 +/- 2%, and 61 +/- 4%, respectively, while lysine vasopressin (0.1 microM) and dibutyryl cAMP (5 mM) stimulated ACTH release by 112 +/- 8% and 220 +/- 4%, respectively. In conclusion, it was shown that the stimuli mentioned above directly affect ACTH secretion by the pituitary tumor cells. The inhibitory action of the met-enkephalin analog and the stimulatory action of naloxone on ACTH secretion make the presence of opiate receptors on this type of tumor likely.
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PMID:A met-enkephalin analog inhibits adrenocorticotropin secretion by cultured pituitary cells from a patient with Nelson's syndrome. 627 Jan 82

The development of two monoclonal antibodies for use as second antibodies in immunocytochemistry is described. The antibodies are produced by mouse X mouse hybrid myelomas, and are both of the IgG type. The two antibodies, RB23 and ND13, were used to detect neurophysin by three-step peroxidase-antiperoxidase (PAP) immunostaining, and were "internally labeled" with 3H-lysine for the radioimmunocytochemical localization of neurophysin, substance P, and tyrosine hydroxylase using rabbit first antibodies. The binding sites of RB23 and ND13 on the rabbit IgG antibodies were determined by solid-phase radioimmunoassay, using allotype-specific rabbit serum to compete with RB23 and ND13. It was found that both RB23 and ND13 are directed against the B4 kappa-light-chain allotype. The immunocytochemical localization of adrenocorticotropic hormone and somatostatin with rabbit primary antibodies was not achieved with RB23 or ND13, and it is proposed that these antibodies are not of the B4 allotype. The findings demonstrate that monoclonal second antibodies can be useful general reagents for conventional immunocytochemistry as well as for radioimmunocytochemistry. Furthermore, allotype-specific monoclonal second antibodies may prove useful in the simultaneous immunohistochemical localization of more than one antigen in a given tissue section.
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PMID:Immunocytochemistry with monoclonal anti-immunoglobulin as a developing reagent: application to immunoperoxidase staining and radioimmunocytochemistry. 641 91

The characteristics of terbium-161 diethylene triamine penta-acetic acid (DTPA) labelled octreotide with respect to specific binding to somatostatin (octreotide) receptors on rat brain cortex membranes, biological activity, uptake and excretion by isolated perfused rat livers and metabolism in vivo in normal and tumour-bearing rats were determined and compared to those of indium-111 DTPA-octreotide. The results of the binding studies demonstrate that 161Tb-DTPA-octreotide is a high-affinity radioligand for somatostatin receptors, with an affinity comparable to that of 111In-DTPA-octreotide. Rat growth hormone secretion inhibition experiments showed that 161Tb-DTPA-octreotide has a similar potency to 111In-DTPA-octreotide. 161Tb-DTPA-octreotide appeared to be taken up even less by the isolated perfused rat liver than 111In-DTPA-octreotide, as almost no tracer disappeared from the perfusion medium. Furthermore, hardly any radioactivity was found in the liver, and excretion into the bile was negligible. The biodistribution studies showed that for octreotide receptor-positive organs, such as pancreas and adrenals, uptake of 161Tb-DTPA-octreotide is lower then that of 111In-DTPA-octreotide. However, as the clearance from the blood of the former compound is faster than that of the latter, the tissue/blood ratio is higher in the case of 161Tb-DTPA-octreotide than with 111In-DTPA-octreotide. Furthermore, these studies demonstrated that the uptake of 161Tb-DTPA-octreotide by the renal tubular cells after glomerular filtration can be reduced by administration of lysine or sodium maleate. Increase in urine production before and during the experiment had no effect on the kidney uptake of 161Tb-DTPA-octreotide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evaluation in vitro and in rats of 161Tb-DTPA-octreotide, a somatostatin analogue with potential for intraoperative scanning and radiotherapy. 749 21

The ability of TSH to stimulate synthesis and release of thyroid hormones in ovine thyroid follicles in vitro depends partially on a synergy with insulin-like growth factors (IGFs). The cellular availability of IGFs may be influenced by the release of several IGF binding proteins (IGFBPs). The purposes of these studies was to 1) further characterize the species of IGFBPs synthesized by thyroid follicles, 2) examine the ability of TSH and cortisol to alter IGFBP gene expression and protein release, and 3) investigate the actions of exogenous IGFBPs on thyroid cell function. Adult sheep thyroid follicles were isolated after collagenase digestion, grown to confluence in Coon's modified Ham's F12M medium (OH) with the addition of transferrin, glycylhistidyl-lysine, somatostatin (3H), cortisol and insulin, and maintained in serum-free test media with or without further supplements for up to 48 h. Conditioned media were analyzed for IGFBP presence by Western ligand blotting, and by immunoblotting using specific antisera against bovine IGFBP-2 and human IGFBP-5. IGFBP mRNAs from follicles were identified by Northern blot hybridization using [32P]labeled complementary DNAs encoding ovine IGFBP-1 or -2, and rat IGFBP-4, -5, or -6. Uptake and organification of Na[125I] were measured by incorporation into trichloroacetic acid-precipitable material. Isolated thyroid follicles synthesized four species of IGFBPs in either 0H or 3H medium as detected by ligand blotting, of sizes 40-46, 34, 28, and 18 kilodaltons (kDa), respectively. The 32 kDa IGFBP was identified immunologically as IGFBP-2, whereas the 28 kDa and 18 kDa species were identified as IGFBP-5. Northern blot hybridization of total RNA from cells in 3H medium demonstrated an IGFBP-2 messenger RNA (mRNA) [1.4 kilobase (kb)], an IGFBP-4 mRNA (2.6 kb), and two IGFBP-5 mRNAs (6 kb and 1.8 kb). No IGFBP-1 or -6 mRNAs were detected. Incubation of cultured follicles with TSH (30-500 microU/ml) caused a dose-dependent decrease in the abundance of all IGFBP mRNAs and released proteins, which were reduced further by TSH together with cortisol (10 nM). When the inhibitory effect of TSH and cortisol was removed, IGFBP-2 mRNA increased within 3 h and was 7-fold greater within 12 h. IGFBP-2 did not appear in the conditioned medium until 12 h after TSH removal, along with the other IGFBP species.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Hormonal regulation and biological actions of insulin-like growth factor binding proteins in isolated ovine thyroid follicles. 750 36

Isolated sheep thyroid follicles release insulin-like growth factors (IGF)-I and -II together with IGF-binding proteins (IGFBPs). We previously showed that TSH suppresses the biosynthesis and release of IGFBPs in vitro which may increase the tissue availability of IGFs, allowing a synergy with TSH which potentiates both thyroid growth and function. Many of the actions of TSH on thyroid cell function are dependent upon activation of adenylate cyclase, although increased synthesis of inositol trisphosphate and activation of protein kinase C (PKC) have also been implicated. We have now examined whether probable changes in intracellular cyclic adenosine monophosphate (cAMP) or PKC are involved in TSH-mediated suppression of IGFBP release. Confluent primary cultures of ovine thyroid cells were maintained in serum-free Ham's modified F-12M medium containing transferrin, somatostatin and glycyl-histidyl-lysine (designated 3H), and further supplemented with sodium iodide (10(-8)-10(-3) mol/l), dibutyryl cAMP (0.25-1 mmol/l), forskolin (5-20 mumol/l) or 12-O-tetradecanoylphorbol-13-acetate (TPA; 10(-11)-10(-6) mol/l), with or without exposure to TSH (200 microU/ml). The uptake and organification of Na [125I] by cells was examined after test incubations of up to 48 h, and IGFBPs in conditioned media were analysed by ligand blot using 125I-labelled IGF-II. The PKC activity in the cytosol and plasma membrane fractions of cells was measured by phosphorylation of histone using [gamma-32P]ATP, and PKC immunoreactivity was visualized by Western immunoblot analysis. While dibutyryl cAMP or forskolin largely reproduced the stimulatory effect of TSH on iodine organification, they did not mimic the inhibitory effect of TSH on the secretion of IGFBPs of 43, 34, 28 and 19 kDa. Incubation with physiological or pharmacological concentrations of iodide (10(-6)-10(-3) mol/l) for up to 48 h significantly decreased TSH action on iodide uptake and organification but did not alter the inhibitory action of TSH on IGFBP release. Incubation of cells with 10(-11)-10(-6) mol TPA/l for 24 h inhibited the subsequent ability of TSH both to potentiate iodine organification and to suppress IGFBP release. In 3H medium, PKC activity was predominantly recovered from the membrane fraction but, following incubation for 48 h with TSH, the enzyme was no longer translocated to the membrane and was recovered predominantly from the cytosol.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Role of 3', 5' cyclic adenosine monophosphate and protein kinase C in the regulation of insulin-like growth factor-binding protein secretion by thyroid-stimulating hormone in isolated ovine thyroid cells. 751 34

We examined the effects of thyroid-stimulating hormone (TSH) on basic fibroblast growth factor (basic FGF) expression in isolated ovine thyroid follicles in vitro, and the effects of exogenous basic FGF on thyroid growth and function, to elucidate the significance of increased basic FGF expression during TSH-induced rat thyroid hyperplasia in vivo. Primary cultures of ovine thyroid follicles were maintained in serum-free Ham's modified F-12M medium containing transferrin, somatostatin, and glycyl-histidyl-lysine (designated 3H) with or without basic FGF alone, or in combination with TSH (100 microU/mL) and cortisol (10 nM). Following 48 h incubation, cells were harvested and total RNA prepared for the detection of basic FGF mRNA using Northern blot analysis and ribonuclease protection assay. Basic FGF in the cytoplasm and extracellular matrix fractions was quantified by radioimmunoassay. Basic FGF mRNA transcripts of 3.7, 3.0, and 2.2 kb, respectively, were found in thyroid follicles cultured in 3H medium, and the abundance of each increased between 2- and 3-fold following incubation with 10-50 microU/mL TSH, although higher concentrations of TSH were less effective. Similar results were seen using a more sensitive ribonuclease protection assay. Cells cultured in control, 3H medium contained 2.4 +/- 0.5 fmol immunoreactive basic FGF/micrograms cell DNA within the cytoplasm and 21.1 +/- 1.5 fmol/micrograms DNA within the extracellular matrix (mean +/- SD, n = 6). A significant increase (p < 0.05) in basic FGF content was seen in both cell compartments following incubation with 50 or 100 microU/mL TSH, while 250 microU/mL was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Basic fibroblast growth factor (basic FGF) in isolated ovine thyroid follicles: thyrotropin stimulation and effects of basic FGF on DNA synthesis, iodine uptake and organification, and the release of insulin-like growth factors (IGFs) and IGF-binding proteins. 751 16

A previous in vivo study implicated the YAP3 and KEX2 genes in the proteolytic maturation of anglerfish prosomatostatins which were heterologously expressed in the yeast Saccharomyces cerevisiae. In the present report, we have determined the cleavage specificity of these enzymes by incubating them in vitro with synthetic peptides mimicking the potential processing sites present in the somatostatin precursors and with full length prosomatostatin I. The Yap3 enzyme was prepared from a membrane fraction of a YAP3-overexpressing yeast, and a soluble form of Kex2 obtained from the culture medium of insect cells which had been infected with a recombinant baculovirus expressing the KEX2 gene. The identity of the cleavage products was confirmed by amino acid analysis. Our results show that both endoproteases generate mature SRIF-28 from prosomatostatin-II but that only Yap3 can process the homologous monobasic cleavage site (ie single arginine residue) found in prosomatostatin-I. Both enzymes were also shown to recognize the Arg-Lys doublet found in prosomatostatin-I producing a lysine-extended form of SRIF-14, which indicates that cleavage occurred C-terminal to the arginine residue. In addition, Kex2 also hydrolyzed C-terminal to the Pro-Arg motif to release a tripeptide-extended form of SRIF-14. However, neither endoprotease could cleave after the Arg-Lys doublet to release mature SRIF-14. Taken together, our results indicate that the yeast Kex2 and Yap3 endoproteases have distinct, though overlapping, substrate specificities. The results also strongly support the role of Yap3 as a proprotein convertase which perhaps defines a new family of processing enzymes.
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PMID:Cleavage of prosomatostatins by the yeast Yap3 and Kex2 endoprotease. 781 27

The neuropharmacologic basis of infantile spasms and the mechanism by which adrenocorticotropic hormone (ACTH) exerts its therapeutic effects are unknown. This is a critical review of cerebrospinal fluid neurotransmitters or their metabolites in infantile spasms before and during treatment with ACTH, and of clinical drug trials with drugs acting on neurotransmission. Cerebrospinal fluid studies have shown lower gamma-aminobutyric acid (GABA), ACTH, and 5-hydroxyindoleacetic acid concentrations in patients with infantile spasms compared to controls, elevated lysine and glutamate, variable or no differences in homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, norepinephrine, corticotropin-releasing hormone, and beta-endorphin. Chronic treatment with ACTH in infantile spasms reduces cerebrospinal fluid GABA, beta-endorphin, and somatostatin, increases norepinephrine and tyrosine, and has variable or no effect on homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, 5-hydroxyindoleacetic acid, histamine, and tryptophan. Small therapeutic trials with drugs that act through different neurotransmitters such as methysergide, alpha-methylparatyrosine, various benzodiazepine agonists, and vigabatrin lend some support to a role for GABA and monoamines in infantile spasms. These data, though promising, provide only a hint of potential neurotransmitter disturbances, and more basic and clinical data are needed.
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PMID:Putative neurotransmitter abnormalities in infantile spasms: cerebrospinal fluid neurochemistry and drug effects. 791 15


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