Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tyrosine aminotransferase (TAT) induction by glucagon and dexamethasone in the liver of tumor-bearing chickens was studied and compared with induction in healthy animals. The transplantable tumor was caused by inoculation of cells from a cell line induced by MC29 avian leukosis virus. TAT was hardly detectable in tumor tissue of control and dexamethasone-treated chickens, but it was induced by glucagon to levels which were significant although very low when compared to those in host liver or the liver of non-tumor-bearing controls after glucagon treatment. Dexamethasone failed to induce TAT in host liver at 8 A.M. while it significantly indiced TAT in the normal liver at the same time of the day. Similar failure of TAT induction was not detectable when glucagon was used instead of dexamethasone. Furthermore, it was found that diurnal variations in basal and dexamethasone or glucagon-induced TAT levels are considerably mitigated in host liver as compared to those observed in the liver of healthy animals. The possible reasons for these findings are discussed.
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PMID:Tyrosine aminotransferase induction in normal and tumor-bearing chickens. 0 Mar 37

A radioimmunoassay procedure for guanosine 3',5'-cyclic monophosphate (CGMP) is described. The procedure is based on competitive binding between [3H]CGMP and non-radioactive CGMP, with separation of bound and unbound CGMP by Millipore filtration. The binding reaction showed very high specificity to CGMP, had a broad pH optimum, and reached equilibrium within a short time. A simple procedure for the pruification of assay samples using Dowex AG 50W-X2 resin is also described. CGMP contents in urine samples were assayed without purification. Injection of glucagon into healthy human volunteers resulted in a small but significant reduction in urinary CGMP level, whereas CAMP excretion increased dramatically.
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PMID:Rapid radioimmunoassay for guanosine 3',5'-cyclic monophosphate using tritiated ligand. 0 Mar 74

Acetylated derivatives of glucagon have been prepared by reacting this hormone under various conditions with acetic anhydride. They have been chemically characterized by the use of a 14C-labeled reagent, by peptide mapping techniques following hydrolysis by pronase and chymotrypsin, and by spectroscopy. Acetylation in sodium acetate (pH 5.5) results in a full substitution of the alpha-amino group of the N-terminal histidyl residue, but in a partial (about 0.3 acetyl group per residue) substitution of the epsilon-amino group of the lysyl residue 12. The monosubstituted (on the alpha-amino group) and the disubstituted (on both amino groups) acetylated components have been separated by chromatography on DEAE-cellulose and CM-cellulose. Acetylation in sodium bicarbonate (pH 8.0) results in a complete substitution of both amino groups and of the hydroxyl groups of the tyrosyl residues 10 and 13. Complete deacetylation of the O-acetyltyrosyl residues occurs upon treatment with hydroxyl-amine. Mono, di and tetraacetylglucagon are homogeneous when analyzed by disc gel electrophoresis; di and tetrasubstituted derivatives show an increased mobility towards the anode. 125I-labeled derivatives of acetylglucagon show higher distribution coefficients in the aqueous two-phase dextran/poly(ethylene glycol) system than do similar derivatives of glucagon. Acetylation decreases in parallel the ability of glucagon to stimulate the activity of adenylate cyclase and to bind to its receptors in liver cell membranes of the rat. The biological potencies of the mono, di and tetrasubstituted derivates are, respectively, about 10, 1 and 0.1% that of native glucagon. The binding properties of the material dissociated from the acetylglucagon-receptor complex suggest that the reduction in biological activity results from a decrease in the intrinsic affinity of the modified glucagon for the receptors, as well as from the presence of small amounts of residual, unreacted glucagon. Studies with 125I-labeled derivatives of glucagon indicate that acetylation decreases the rate of association and increases the rate of dissociation of the hormone-receptor complex.
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PMID:Acetylglucagon: preparation and characterization. 0 Dec 70

The need for chaotropic eluents in immunoaffinity chromatography is a consequence of the high affinities of antibodies towards their antigens. This affinity is decreased and elution of antiglucagon antibodies from a column of immobilized glucagon can be achieved under mild conditions when the steric complementarity to the antibody binding site is perturbed by selective chemical modification of the hormone. The effects of reaction with 2-hydroxy-5-nitrobenzyl bromide, tetranitromethane and hydrogen peroxide have been studied. Conversely, treatment of immobilized antibodies with 2-hydroxy-5-nitrobenzyl bromide facilitates the elution of glucagon during immunoaffinity chromatography. The general implications of these results are discussed.
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PMID:Avoidance of strongly chaotropic eluents for immunoaffinity chromatography by chemical modification of immobilized ligand. 0 98

A membrane preparation was obtained from rat striated muscle. The preparation used has been shown to contain plasma membranes by electron microscopy as well as by enrichment in specific activity of both a plasma membrane enzyme "marker" (5'-nucleotidase) and cell surface 125I-incorporated radioactivity. The characteristics of 125I-insulin binding to this striated muscle preparation were studied, and it was found that 125I-insulin readily and specifically binds to this membrane preparation. The binding reaction was time, pH, and temperature dependent with optimal steady-state binding conditions occurring at 20 degrees C and at pH 7.6. Under these conditions (20 degrees C, pH 7.6) skeletal muscle plasma membranes displayed little ability to degrade insulin. Binding of 125I-insulin was readily inhibited at physiologic concentrations of unlabeled insulin and the specificity of this receptor for insulin was demonstrated by finding that high concentrations of glucagon, b-LH, b-FSH, p-PRL, hCG, TSH, and HGH were without effect on 125I-insulin binding and that insulin analogues inhibited binding in proportion to their biologic activity. When membranes from older, fatter rats were compared to membranes from younger, lean animals, 5'-nucleotidase specific activity and insulin degrading activity were found to be comparable. On the other hand, insulin binding to membrane receptors was decreased 30%-40% in the older, fatter animals. Thus, these studies indicate that (1) specific insulin receptors exist in skeletal muscle plasma membranes, and (2) membranes from older, fatter rats have fewer receptors than those from younger, lean animals.
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PMID:Insulin receptors of skeletal muscle: specific insulin binding sites and demonstration of decreased numbers of sites in obese rats. 0 34

(1) A system is described for studying the short-term effects of agents on proinsulin synthesis in vitro, as measured by the incorporation of [3H]leucine into isolated proinsulin. (2) Of the agents tested, glucose has the most marked, and apparently earliest, effect on proinsulin synthesis. (3) The adenyl cyclase system participates in the regulation of proinsulin synthesis since exogenous cyclic AMP, glucagon, and caffeine are stimulatory. When cyclic AMP is added to the medium in the presence of glucose, it is the most potent agent acting on the adenyl cyclase-phosphodiesterase system. (4) The addition of NADPH to isolated rat islets inhibits proinsulin and Bulk Protein synthesis in vitro.
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PMID:Regulation of proinsulin synthesis in isolated rat islets. 0 29

150-200 g heavy, Walker-carcinoma bearing, male Sprague-Dawley-rats showed rapid, tumour weight dependent, loss of liver glycogen until complete depletion in tumour groups heavier than 40 g/animal. Simultaneously the glycogen mobilization after massive glucagon stimulation, was successivly diminished and finally abolished in different groups with increasing tumor weight. Concomitantly the spontaneous and stimulated activity of liver phosphorylase a was found markedly reduced in advanced tumour cachexia, the extent of stimulation of liver phosphorylase a activity by intracardial injections of epinephrine not being altered. Tumour induced inhibition of glycogen mobilization thus appears to have been excluded. To account for the relative late pronounced hypoglycemia in peripherial rat blood in face of the early loss of liver glycogen, accelerated gluconeogenesis has been postulated. In accord with this spontaneous rise in liver tyrosine amino transferase was found in tumour bearing rats along with a doubled maximal stimulation value after medrol injection as compared to control groups. This behavior could not be shown for liver alanine aminotransferase and liver fructose 1,6-di-phosphatase. The former showed no differences between control and tumour groups neither of spontaneous nor of stimulated activity. The latter showed only a very reluctant rise after massive stimulation by triamcinolone for 3 days in the control groups, the tumour bearing groups showing no deviation from spontaneous control values.
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PMID:[Biochemical investigations of cancer cachexia. II. Depletion of glycogenolysis and stimulation of gluconeogenesis in Walker carcinoma 256 bearing rats (author's transl)]. 0 45

A number of hemodynamic, pharmacologic and metabolic interventions were found to change the extent of acute ischemic injury of the myocardium and subsequent necrosis following experimental coronary artery occlusion. Reduction in myocardial damage occurred by decreasing myocardial oxygen demands (beta-adrenergic blocking agents, intra-aortic balloon counterpulsation, external counterpulsation, nitroglycerin, decreasing afterload in hypertensive patients, inhibition of lipolysis, and digitalis in the failing heart); by increasing myocardial oxygen supply either directly (coronary artery reperfusion or elevating arterial pO2), or through collateral vessels (elevation of coronary perfusion pressure by alpha-adrenergic agonists, intra-aortic balloon counterpulsation); or by increasing plasma osmolality (mannitol, hypertonic glucose); presumably by augmenting anaerobic metabolism (glucose-insulin-potassium, hypertonic glucose); by enhancing transport to the ischemic zone of substrates utilized in energy production (hyaluronidase); by protecting against autolytic and heterolytic damage (hydrocortisone, cobra venom factor, aprotinin). Augmentation of myocardial ischemic damage occurred as a consequence of increasing myocardial oxygen requirements (isoproterenol, glucagon, ouabain, bretylium tosylate, tachycardia); by decreasing myocardial oxygen supply either directly (hypoxia, anemia) or through reduction of collateral flow (hemorrhagic hypotension, minoxidil) or by decreasing substrate availability glycemia). Pilot studies have been carried out in patients with hyaluronidase, nitroglycerin, intra-aortic balloon counterpulsation, beta-blocking agents and Arfonad and have shown that these interventions may also reduce myocardial damage, suggesting that the concept of reduction in infarct size following coronary occlusion is applicable clinically.
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PMID:Effects of metabolic and pharmacologic interventions on myocardial infarct size following coronary occlusion. 0 95

The specificity of thermomycolase toward glucagon and the oxidized A and B chains of insulin was investigated. Extensive digestion of glucagon occurred when conducted at pH 7.0 and 45 degrees C for 40 min, whereas hydrolysis of only three peptide bonds occurred at pH 7.0 and 28 degrees C for 5 min. A similar situation was observed for the oxidized B chain of insulin, which exhibited only a single major cleavage after 5 min at 25 degrees C. No well-defined specificity for particular amino acid residues was evident, but ready hydrolysis of peptide bonds occurred within sequences containing non-polar residues. This endoproteinase must therefore possess an extended hydrophobic binding site for polypeptides. Thermomycolase hydrolysed acetylalanylalanylalanine methyl ester and elastin-Congo Red at 22 and 8.5 times the rate of porcine elastase respectively. A limited degradation of native collagen and significant hydrolysis of benzyloxycarbonyl-Gly-Pro-Leu-Gly-Pro were suggestive of some collagenase-like activity. No keratinase activity was apparent.
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PMID:The substrate specificity of thermomycolase, an extracellular serine proteinase from the thermophilic fungus Malbranchea pulchella var. sulfurea. 0 73

In cell-free preparations (washed 600 x g pellets) of human renal medulla, glucagon produced a dose-dependent stimulation of adenylate cyclase. The stimulation of renal medullary adenylate cyclase by saturating concentrations of glucagon was additive to the saturating doses of vasopressin. Furthermore, L-isoproterenol stimulated renal medullary adenylate cyclase in a dose-dependent manner, and this stimulation was blocked by DL-propranolol. Stimulation of the renal medullary adenylate cyclase by maximal doses of glucagon and L-isoproterenol was additive. DL-Propranolol did not inhibit stimulation of glucagon. Thus, the results indicate the existence of a specific adenylate cyclase that is responsive to glucagon--distinct from the isoproterenol-sensitive adenylate cyclase and the previously described vasopressin-sensitive adenylate cyclase in human renal medulla. We suggest that the renal tubular effect of glucagon may be mediated by glucagon-dependent cyclic-AMP production in renal tissue.
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PMID:Glucagon-sensitive adenylate cyclase in human renal medulla. 0 66


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