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)

Immunocytochemical staining experiments on filter paper or nitrocellulose models reveal that many, but not all, neurohormonal peptides, as well as poly-L-lysine, strongly bind a number of labeled reporter molecules, including colloidal gold- or peroxidase-labeled IgG, protein A, streptavidin, and albumin. Peptides displaying this type of (nonspecific) binding are basic; they include ACTH, VIP, opioid peptides, and poly-L-lysine. Pre-absorption of labeled probes with excess ACTH[1-24] or poly-L-lysine abolishes or greatly reduces binding not only to the homologous but also to the heterologous peptides tested. A number of cell types previously reported to display nonspecific immunoglobulin binding contain one or several of the basic neurohormonal peptides shown to display nonspecific absorption of labeled IgG, protein A, streptavidin, and albumin. This nonspecific absorption is reversed neither by high salt nor high pH conditions, nor by a number of detergents and blocking proteins. One dynorphin antiserum also displays nonspecific binding to the peptides as well as to pancreatic glucagon cells, and this nonspecific staining can be blocked by basic peptide pre-absorption (whether homologous or heterologous). These results suggest a need for caution when immunocytochemical studies of a number of basic polypeptides are interpreted, and also suggest the inclusion of novel control procedures in immunocytochemistry.
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PMID:Nonspecific immunocytochemical reactions with certain neurohormonal peptides and basic peptide sequences. 287 24

We demonstrated the presence and the secretion in vivo and in vitro of immunoreactive preproenkephalin B-derived opioid peptides (alpha-neoendorphin, dynorphin and leumorphin) in human phaeochromocytomas. In seventeen human phaeochromocytomas and two human adrenal medullas, the tissue contents of immunoreactive preproenkephalin B-derived opioid peptides (alpha-neoendorphin, dynorphin and leumorphin) and leu-enkephalin were studied by specific RIAs. Compared with a remarkable wide distribution in amounts of immunoreactive leu-enkephalin (1063 +/- 437 pg/mg, mean +/- SE), small amounts of immunoreactive alpha-neoendorphin (22.6 +/- 6.4 pg/mg) and dynorphin (8.5 +/- 1.2 pg/mg) were detected in all seventeen human phaeochromocytomas and the two human adrenal medullas. Leumorphin-like immunoreactivity was detected in only four tumours. Gel chromatographic studies revealed the presence of preproenkephalin B-derived peptides and their high molecular forms. A significant positive correlation between the tumour tissue contents of immunoreactive alpha-neoendorphin and of dynorphin was observed. Nicotine (10(-5), 10(-4) mol/l) significantly stimulated the secretion of immunoreactive alpha-neoendorphin and dynorphin as well as leu-enkephalin and catecholamines from cultured human phaeochromocytoma cells. Administration of 1 mg of glucagon to a patient with medullary phaeochromocytoma induced a rapid increase in the plasma concentration of immunoreactive alpha-neoendorphin with a concomitant increase in plasma catecholamines. These results indicate the presence of preproenkephalin B-derived opioid peptides in human phaeochromocytomas and human adrenal medullas and their secretion in human phaeochromocytomas.
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PMID:Preproenkephalin B-derived opioid peptides in human phaeochromocytomas. 288 41

Neuroendocrine (NE) neoplasms of the human bronchopulmonary tract were examined by electron microscopy, immunocytochemistry, and gel electrophoresis of cytoskeletal proteins from microdissected tissue samples. All samples (carcinoids, well-differentiated NE carcinoma, NE carcinomas of intermediate type, NE carcinomas of the small cell type) contained significant numbers of cells that immunostained for one or more of the following neuroendocrine markers tested: bombesin, calcitonin, ACTH, leu-enkephalin, gastrin, serotonin, somatostatin, alpha-melanocyte-stimulating hormone, vasoactive intestinal peptide, glucagon, insulin, substance P, and neuron-specific enolase. Electron microscopy revealed typical NE cell features, including variable abundant and frequently heterogeneous neurosecretory granules. Tumor cells contained filaments specifically stained with different conventional and monoclonal antibodies to cytokeratins and displayed punctate plasma membrane staining with antibodies to desmoplakins, in agreement with the electron microscopic demonstration of tonofilament bundles and desmosomes. Immunocytochemistry for NE markers and cytoskeletal proteins on consecutive sections revealed both cytokeratins and neuroendocrine substances in single cells. Using gel electrophoresis of cytoskeletal proteins of tissue regions extracted with high salt buffer and detergent, we could detect, in the tumors tested, appreciable amounts of cytokeratin polypeptides 8, 18, and 19, i.e., major cytokeratins also found in certain other lung carcinomas such as adenocarcinomas. Tumor cells were not significantly stained with antibodies to other intermediate filament proteins such as vimentin, desmin, glial filament protein, and neurofilament protein. The results show that NE substances can be synthesized in cells containing a typical epithelial cytoskeleton, i.e., cytokeratin filaments and desmosomes. These findings support the notion of an epithelial character of these tumors and appear in contrast with recent reports that neurofilaments are the only type of intermediate filaments present in carcinoids and other pulmonary NE tumors. These observations may have important implications for the histogenesis of NE carcinomas and for diagnostic pathology.
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PMID:Coexpression of neuroendocrine markers and epithelial cytoskeletal proteins in bronchopulmonary neuroendocrine neoplasms. 298 72

Low concentrations of six peptide hormones; glucagon, vasoactive intestinal peptide, substance P, angiotensin II, lysine-vasopressin, arginine-vasopressin, and the chemotactic peptide fMet-Leu-Phe, activated the capacity for pinocytosis in starved Amoeba proteus. Competitive inhibitors of the chemotactic peptide in leucocytes inhibited activation by fMet-Leu-Phe, suggesting that its action in the amoeba is mediated by specific receptors. The opioid peptides, beta-endorphin, dynorphin (1-13) and leu-enkephalin abolished through a naloxone-sensitive mechanism activation by hormones and several other activating agents. Also, low concentrations of beef and pork insulin inhibited activation by peptide hormones. An insulin analogue of low potency in mammalian cells was inactive in the amoeba. These results support the hypothesis that besides opioid receptors, there may be insulin receptors and possibly receptors for several other peptide hormones in Amoeba proteus.
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PMID:Peptides as modifiers of Na+-induced pinocytosis in starved Amoeba proteus. 300 25

Bombesin-like immunoreactivity (BLI), a putative peptidergic neurotransmitter of the gastrointestinal intrinsic nervous system is released from the isolated perfused rat stomach in response to the classical neurotransmitter acetylcholine and in response to other putative peptidergic neurotransmitters such as vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI) or growth hormone releasing factor (GRF). The secretion of BLI is modulated not only by gastric factors such as the intragastric pH but also by changes of perfusate glucose concentrations indicating that alterations of carbohydrate metabolism might have an effect on gastric neuroendocrine regulation. Since previous studies have shown that insulin, the major regulatory hormone of glucose metabolism, reduces gastric somatostatin and glucagon secretion it was of interest to determine the effect of insulin on gastric BLI and gastrin secretion. The experiments were performed in the isolated perfused rat stomach model. The addition of porcine insulin to the perfusate at concentrations of 50 and 100 microU/ml had no effect on basal BLI and gastrin secretion. The infusion of acetylcholine (2 X 10(-6)M and 4 X 10(-6)M) elicited a stimulation of BLI and gastrin secretion which was not altered by the addition of insulin (100 microU/ml). On the other hand, significant effects of insulin were observed during administration of the two putative peptidergic neurotransmitters VIP and leu-enkephalin. The infusion of VIP at 10(-11)M and 10(-8)M had no effect on BLI and gastrin secretion in the absence of insulin, however, with the addition of insulin (100 microU/ml) the higher dose of VIP (10(-8)M) elicited a significant stimulation of BLI secretion while both doses of VIP (10(-11)M and 10(-8)M) significantly increased gastrin release. Similar to VIP the infusion of leu-enkephalin at doses of 10(-9)M and 10(-6)M had no effect on BLI and gastrin secretion in the absence of insulin. When insulin was added to the perfusate both doses of leu-enkephalin elicited a significant stimulation of BLI secretion while gastrin remained unchanged. The addition of the specific opiate receptor antagonist naloxone (10(-5)M) did not block the effect of leu-enkephalin in the presence of insulin. In addition the effect of naloxone was also examined during cholinergic stimulation. The addition of naloxone (10(-5)M) during the infusion of acetylcholine abolished the stimulatory effect on BLI secretion in the absence of insulin, whereas in the presence of insulin naloxone did not alter cholinergically-induced BLI secretion.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effect of insulin on secretion of bombesin-like immunoreactivity and gastrin from the isolated rat stomach in response to acetylcholine, VIP and leucine-enkephalin. 351 44

Twenty-seven cases of medullary carcinoma of the thyroid gland (MCT) were studied by light microscopy, immunocytochemistry, and electron microscopy. Immunoreactivity for neuron-specific enolase (NSE) and calcitonin was present in all tumors. The numbers of peptides and serotonin demonstrated in each case varied from one to eight. Bombesin was present in 18 of the 27 cases, serotonin in 15, leu-enkephalin in 8, somatostatin in 8, gastrin in 3, substance P in 1, vasoactive intestinal peptide (VIP) in 1, and ACTH in 1. Insulin and glucagon were not encountered in any of the tumors. Immunoreactivity for thyroglobulin was seen in five primary tumors as well as in one lymph node metastasis. The finding of concurrent production of calcitonin and thyroglobulin within the same tumor is enough to question the dogma of the separate origin of follicular cells and C-cells. We were unable to attach any clinical importance to the production of multiple peptides and/or amines.
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PMID:Medullary carcinoma of the thyroid gland: an immunocytochemical study. 390 54

Homogeneous porcine calpain (Ca2+-dependent cysteine proteinase) was found to hydrolyze a variety of peptides and synthetic substrates. Leu-Trp-Met-Arg-Phe-Ala, eledoisin-related peptide, alpha-neoendorphin, angiotensin I, luteinizing hormone-releasing hormone, neurotensin, dynorphin, glucagon, and oxidized insulin B chain were cleaved with a general preference for a Tyr, Met, or Arg residue in the P1 position preceded by a Leu or Val residue in the P2 position. No great difference in specificity was found between low-Ca2+-requiring calpain I and high-Ca2+-requiring calpain II. 4-Methylcoumaryl-7-amide (MCA) derivatives having a Leu(or Val)-Met(or Tyr)-MCA or a Leu-Lys-MCA sequence were also cleaved by either calpain I or calpain II with preference for Leu over Val by a factor of 9 to 16. Calpains I and II showed similar but not identical kinetic behavior for individual substrates. The Km and kcat values ranged from 0.23 to 7.08 mM and 0.062 to 0.805 s-1 for the calpains, while kcat/Km values for the calpains were only 1/433 to 1/5 of those for papain with a given substrate. With succinyl-Leu-Met(or Tyr)-MCA, calpains I and II were half-maximally activated at 12 and 260 microM Ca2+, respectively, and competitively inhibited by leupeptin (Ki = 0.32 microM for I and 0.43 microM for II) or antipain (Ki = 1.41 microM for I and 1.45 microM for II). Thus, this is the first report describing the specificity and kinetics of calpains I and II.
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PMID:Comparative specificity and kinetic studies on porcine calpain I and calpain II with naturally occurring peptides and synthetic fluorogenic substrates. 609 35

During the several decades that hormones have been considered for roles in the control of feeding, certain ones have gained special attention, although the role assigned to any one hormone has varied from time to time. Three classes of hormones have been considered in this review: gastrointestinal, brain, and pancreatic. Of these classes, two have obtained the most compelling evidence for a physiological role in the control of feeding. CCK, an intestinal and brain hormone, appears to be involved in satiety. Glucagon of pancreatic origin appears also to play an important role in satiety. These hormones, when sequestered by a specific antibody, cause a delay in satiety and thus increase food intake. Insulin, another pancreatic hormone, has been considered for several roles in the control of feeding. Recently, attention has been given to the possibility that insulin of the CSF provides an integrated link between the metabolic state of the adipose tissue and the brain structures concerned with the control of feeding. Thus, insulin may be a primary hormone involved in the maintenance of energy balance or of body-weight. Finally, brain opiate peptides, e.g. dynorphin, are very likely involved in the transmission of information concerned with the interaction of feeding and maintenance of energy balance. Clearly, hormones play primary roles in the control of feeding behaviour and the regulation of energy balance, but much remains to be done to establish their specific actions or components of the associated physiological systems.
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PMID:Hormones and feed intake. 613 74

Preliminary observations have indicated the existence of characteristic spectra of gastroenteropancreatic (GEP) neurohormonal peptides in endocrine tumors arising in foregut, midgut, and hindgut derivatives. In order to further explore this feature of GEP endocrine neoplasms, islet cell tumors from 14 patients were studied, as were endocrine tumors of the stomach, duodenum, and upper jejunum from 6, 5, and 2 patients, respectively. All tumors were examined immunohistochemically with antisera raised against islet hormones [insulin, somatostatin, glucagon, pancreatic polypeptide (PP)], peptides of the gastrin family [gastrin, cholecystokinin (CCK)], peptides of the secretin family [secretin, vasoactive intestinal peptide (VIP)], and substance P, neurotensin, leu-enkephalin, beta-endorphin, motilin, calcitonin, and ACTH. In addition, an ultrastructural investigation was made. Whenever possible, the immunohistochemical observations were correlated with the clinical manifestations and with the results of radioimmunochemical determination of GEP neurohormones in the blood. The pattern of immunoreactive neurohormonal peptides and the clinical picture were those to be expected in endocrine tumors arising in foregut derivatives. Some principles are proposed for the classification of GEP endocrine tumors on the basis of their histopathologic growth pattern, their spectrum of neurohormonal peptides, and their clinical manifestations.
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PMID:Neurohormonal peptides in endocrine tumors of the pancreas, stomach, and upper small intestine: I. An immunohistochemical study of 27 cases. 613 99

It is now clear that a variety of neuropeptides interact with the more classically defined neurotransmitters to stimulate or inhibit feeding. An extensive peripheral peptide satiety system has been identified. Peptides involved in this system include cholecystokinin, bombesin, gastrin-releasing peptide, glucagon, somatostatin, and possibly thyrotropin-releasing hormone and calcitonin. Some of these peptides appear to inhibit feeding by activating ascending fibers in the vagus, whereas others exert their actions independent of the vagus. In addition, neuropeptides appear to play a role in producing the neuromodulatory effects of taste on appetite, and hormones from the endocrine system modulate neuropeptide effects on feeding. The central appetite regulatory system appears to be arranged in a cascade, with an interaction between dynorphin and dopamine producing a part of the feeding drive. This drive is held in check by a variety of neuropeptides including calcitonin, corticotropin-releasing factor, and bombesin. In turn, these peptides are modulated by a norepinephrine-alpha-aminobutyric acid (GABA) system. Neurotensin, serotonin, cyclohistidyl proline diketopiperazine, and the peripheral satiety system appear to modulate the norepinephrine-GABA disinhibitory system. By the judicious use of neuropharmacological modeling we have developed a model of the neurotransmitter interactions involved in appetite regulation that can act as a springboard for the design of future experiments to unravel the mysteries of appetite regulation.
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PMID:Neuropeptides and appetite: contribution of neuropharmacological modeling. 614 55


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