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V Mutt

Publications and source records attributed to V Mutt.

At least 37 records · Page 2Linked to original sources
PubMed1989

Sheep neuropeptide Y. A third structural type of a highly conserved peptide.

Mammalian forms of neuropeptide Y (NPY) for which the amino acid sequences have previously been determined, are the human, pig, ox, rabbit, rat, and guinea-pig polypeptides. The only difference among these forms is at position 17, where pig and ox NPY have Leu and the others Met. We now show that sheep NPY differs from all the earlier characterized mammalian forms of NPY by having Asp instead of Glu at position 10. At position 17 it has Leu as do both pig and ox NPY. Consequently, 3 different structural types of mammalian NPY are now known.

Amino Acid Sequence↗
PubMed1989

Effect of natural peptide YY on pancreatic secretion and cholecystokinin release in conscious dogs.

The effects of natural peptide YY on pancreatic secretion under different stimulatory conditions and on fatty acid-induced cholecystokinin release were examined in five conscious dogs with pancreatic and gastric fistulas. Intravenous infusion of natural peptide YY at 1 and 0.2 microgram/kg/hr caused 60 and 40% inhibition of secretin- and cholecystokinin-stimulated secretion, respectively, and 40-50 and 20-40% inhibition of intraduodenal oleate stimulated secretion, respectively. A significant but transient decrease in the plasma cholecystokinin level was observed in response to peptide YY under oleate stimulation. The present study demonstrates that peptide YY has a potent inhibitory effect on both exogenously and endogenously stimulated pancreatic secretion and has a mild suppressive effect on fatty acid-induced cholecystokinin release suggesting that this peptide is an important colonic inhibitor of pancreatic secretion.

Animals↗
PubMed1989

Isolation and characterization of a 60-residue intestinal peptide structurally related to the pancreatic secretory type of trypsin inhibitor: influence on insulin secretion.

We have isolated from pig intestine a 60-residue polypeptide initially identified by its inhibition of glucose-induced insulin secretion from perfused pancreas. The amino acid sequence of this porcine polypeptide was determined and found to be markedly similar to that of the pancreatic secretory trypsin inhibitor (41% residue identities). Furthermore, the disulfide arrangements of these two proteins appear identical, suggesting related overall conformations. However, the polypeptide, now named PEC-60 (peptide with N-terminal glutamic acid, C-terminal cysteine, and a total of 60 residues), was found not to inhibit trypsin. The amino acid sequence is also similar to that of a peptide recently isolated from rat bile/pancreatic juice which stimulates the release of cholecystokinin. The biological role of PEC-60 is not known, but the effect on insulin secretion and the homologies observed suggest important biological activities and interesting structural relationships.

Amino Acid Sequence↗
PubMed1989

Antibacterial peptides from pig intestine: isolation of a mammalian cecropin.

Pig small intestine was used as starting material for a batchwise isolation of a peptide fraction enriched in antibacterial activities against Escherichia coli (anti-Ec factor) and against Bacillus megaterium (anti-Bm factor). Separation and further purification were by different types of chromatography. Sequence analysis showed the anti-Bm factor to be apparently similar to vasoactive intestinal peptide. The anti-Ec factor was found to have a 31-residue sequence that was cecropin-like. It was named cecropin P1 and its structure was confirmed by solid-phase synthesis. Synthetic cecropin P1 with and without C-terminal amide was assayed on eight different bacteria. Mobility comparison between synthetic and natural cecropin P1 indicates that the natural peptide has a free C-terminal carboxyl group.

Amino Acid Sequence↗
PubMed1989

Ulcerogenic tumor syndrome of the pancreas associated with a nongastrin acid secretagogue.

Among 30 patients with islet cell neoplasms or hyperplasia who exhibited marked gastric acid hypersecretion and peptic ulceration and/or diarrhea, fasting plasma gastrin concentrations were less than 150 pg/ml in 11 patients, whereas the remaining 19 patients had hypergastrinemia. Plasma extracts from seven of these 11 patients were assayed for acid secretagogue activity in rats. All seven plasma extracts had secretagogue activity that was not found in the plasma extracts of ten patients with ordinary duodenal ulcer disease. Each of the tumor or pancreatic tissue extracts obtained from nine patients exhibited secretagogue activity in rats even though tissue gastrin content was 101.9 pmol (213.8 ng).g-1 or less. The secretagogue activity of the tumor extracts was confirmed in conscious gastric fistula dogs. The tumors' secretagogue activity, in contrast to gastrin, was destroyed by trypsin. It was eluted between porcine motilin and human gastrin I from a Sephadex G-50 (Pharmacia LKB Biotechnology, Inc., Piscataway, NJ) superfine column and was not retained by CM-cellulose, at pH 8.5. Its retention time during reverse phase HPLC on a C18 column also differed from those of G17 and G34. Thus, this secretagogue activity appeared mediated by a small, acidic peptide with a molecular size of about 2000 to 3000 daltons. The present study indicates that plasma and tumor extracts of these 11 patients contain a gastric acid secretagogue activity mediated by a nongastrin peptide. We suggest that what may be a distinct clinical entity associated with endocrine neoplasms of the pancreas should be considered in the face of excessive acid hypersecretion without fasting hypergastrinemia.

Adult↗
PubMed1989

The therapeutic potential of neuropeptides and monoamines as antagonists of lymphocyte activation.

Neuropeptides and monoamines are found in tissues where immune reactions are initiated such as the skin, gut and respiratory tract. In these tissues they might influence lymphocyte activation in inflammatory diseases. Both stimulatory and inhibitory effects have been described. The inhibitory effects may prove to be of pathophysiological and pharmacological importance. Studies both in vitro and in vivo showing that various neuropeptides and monoamines may inhibit reactions such as T lymphocyte proliferation, Blymphocyte proliferation and antibody synthesis, lymphocyte migration and cytotoxicity, are reviewed.

Animals↗
PubMed1988

Isolation and characterization of porcine diazepam-binding inhibitor, a polypeptide not only of cerebral occurrence but also common in intestinal tissues and with effects on regulation of insulin release.

The polypeptide DBI (diazepam-binding inhibitor) has been purified from the porcine upper intestine, where it is abundant. Porcine mature DBI is composed of 86 amino acid residues and has a blocked N-terminus. The primary structure, the first DBI structure determined at the protein level, differs from those indirectly deduced for human and rat DBI at 11 and 17 positions, respectively. In total, the three mammalian DBIs differ at 22 positions but have exactly identical C-terminal 11-residue segments, highly charged and ending with C-terminal isoleucine. The porcine DBI inhibits both the early and the late phase of glucose-induced insulin release from the isolated perfused rat pancreas. Thus, the results identify by direct analysis the presence of DBI at a non-cerebral localization (gut), establish a novel structural form (porcine) and demonstrate a novel bioactivity (on insulin release). These aspects are of special interest in relation to the conserved segments, including the one at the C-terminal end, which may constitute functionally important parts of the polypeptide. It is possible that DBI belongs to a new family of gut polypeptides which inhibit glucose-mediated insulin release by hormonal and/or neurocrine mechanisms.

Amino Acid Sequence↗
PubMed1988

Effect of neuropeptides and monoamines on lymphocyte activation.

Neuropeptides and monoamines have been found in tissues where immune reactions are initiated such as the skin, gut, and respiratory tract, and in these tissues neuropeptides and monoamines might be involved in the regulation of lymphocyte activation. Studies both in in vitro and in vivo showing that various neuropeptides and monoamines may influence reactions such as T lymphocyte proliferation, B lymphocyte proliferation, and antibody synthesis, lymphocyte migration, and cytotoxicity will be reviewed.

Animals↗
PubMed1988

Isolation from porcine intestinal extracts of a cholecystokinin-like peptide and a peptide with homology to cytochrome oxidase polypeptide VII and chymodenin.

A number of different forms of cholecystokinin (CCK) exist in the brain and intestine. Gel permeation and ion exchange chromatography and high performance liquid chromatography have been used to isolate a peptide from partially purified porcine intestinal extracts with N-terminal homology to porcine brain CCK-58. This peptide contracted both the guinea pig ileum longitudinal muscle and gallbladder muscle and these responses were inhibited by dibutyryl cyclic GMP or proglumide. The potency was approximately 1/100 of that of CCK-8. The reason for this low potency is unclear, but it is possible that a critical part of the biologically active region is modified or that it is a truncated form of CCK-58. A further peptide was isolated with a sequence homologous to cytochrome oxidase polypeptide VII and chymodenin.

Amino Acid Sequence↗
PubMed1987

Isolation and structural characterization of porcine coupling factor 6 from intestinal tissues.

A polypeptide purified from an extract of thermostable, porcine intestinal peptides was found to correspond to coupling factor 6, previously known as a component of the mitochondrial oxidative phosphorylation system. The intestinal presence of this peptide offers a new source for preparation of the component in large quantities, and possibly suggests further functions of the polypeptide. Amino acid sequence analysis of this porcine form reveals it to be identical to the bovine form, except for two replacements, at position 62 (Thr in the porcine, Phe/Thr in the bovine form), and position 70 (Ala/Val). The extensive conservation suggests strict structural constraints on the functional properties of the polypeptide.

Adenosine Triphosphatases↗
PubMed1987

Analysis of peptide histidine-isoleucine/vasoactive intestinal polypeptide-immunoreactive neurons in the central nervous system with special reference to their relation to corticotropin releasing factor- and enkephalin-like immunoreactivities in the paraventricular hypothalamic nucleus.

The distribution of peptide histidine-isoleucine (PHI) and vasoactive intestinal polypeptide (VIP), two peptides derived from the same precursor molecule, was analysed with immunohistochemistry in the central nervous system of the rat, and to a limited extent in some other species including sheep, monkey and man. Special attention was focused on possible cross-reactivity between PHI antisera and corticotropin releasing factor in parvocellular neurons in the hypothalamic paraventricular nucleus projecting to the external layer of the median eminence. (1) Characterization of the PHI and VIP antisera revealed that they recognized different sequences of the peptide molecules. One of the PHI antisera (PHI-N), although mainly N-terminally directed, also probably contained an antibody population directed against the C-terminal amino acid in PHI which is an amidated isoleucine. Rat and human corticotropin releasing factor but not ovine also have an amidated isoleucine in C-terminal position. (2) PHI- and VIP-like immunoreactivity were found with parallel and overlapping distribution in all areas investigated in the rat central nervous system. In many cases coexistence of the two immunoreactivities could be directly demonstrated. PHI neurons were found in some areas so far not know to contain PHI/VIP neurons, including the dorsal septum, the septofimbrial nucleus, the stria terminalis and lamina V of the spinal cord. (3) Using an antiserum directed against the amino acid sequence 111-122 of the VIP/PHI precursor, immunoreactive cell bodies were seen in some areas containing VIP and PHI neurons. PHI- and VIP-like immunoreactivity were expressed in parallel in increasing amounts in the superficial laminae of the dorsal horn after transection of the sciatic nerve [G. P. McGregor et al. (1984) Neuroscience 13, 207-216; S. A. S. Shehab and M. E. Atkinson (1984) J. Anat. 139, 725; S. A. S. Shehab and M. E. Atkinson (1986) Expl Brain Res. 62, 422-430]. (5) The PHI-N antiserum stains large numbers of immunoreactive cells in the parvocellular part of the paraventricular nucleus and these cells are mostly identical with corticotropin releasing factor-positive neurons. Absorption experiments suggested that this PHI-N-like immunoreactivity to a large extent represented cross-reactivity with rat CRF and that earlier demonstration of many PHI-positive neurons in the paraventricular nucleus probably represents an artefact as proposed by F. Berkenbosch et al. (Neuroendocrinology 44, 338-346). However, some cells did, in fact, contain VIP- as well as PHI-like immunoreactivity as was shown with antisera not cross-reacting with corticotropin releasing factor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Valosin stimulates gastric and exocrine pancreatic secretion and inhibits fasting small intestinal myoelectric activity in the dog.

Valosin, a novel 25-amino acid gastrointestinal peptide with N-terminal valine and C-terminal tyrosine, has recently been isolated from porcine upper gut extracts. Its physiologic role is unknown and it does not belong to one of the structurally related gut peptide families. Assuming that valosin may influence gastrointestinal functions, we investigated the effect of high-performance liquid chromatography-pure valosin on gastric and exocrine pancreatic secretion and on the intestinal myoelectric activity in conscious dogs. Intravenous injection of valosin (0.125-1 microgram/kg) dose-dependently increased gastric acid secretion 80-fold over basal, corresponding to 18% of the maximal pentagastrin-induced effect. Pepsin output increased 10-fold over basal (30% of the pentagastrin-stimulated secretion). Half-maximal stimulation by pentagastrin could be further increased dose-dependently by simultaneous administration of valosin. Pancreatic bicarbonate secretion was stimulated 11-fold over basal at 1.0 microgram/kg, reaching about 6% of the secretin-induced maximal output, whereas protein secretion increased 12-fold over basal, corresponding to about 55% of the cholecystokinin-induced maximal output. In fasted dogs, spontaneously occurring migrating myoelectric complexes were substantially delayed during infusion of valosin at a dose of 0.2 microgram/kg. These experiments indicate that valosin may represent a novel member of the regulatory gastrointestinal peptides.

Animals↗
PubMed1987

Pancreastatin and islet hormone release.

The effect of pancreastatin on the release of insulin, glucagon, and somatostatin was studied in the isolated perfused rat pancreas. After an initial equilibration period (-20 to 0 min) with a basal glucose concentration (3.3 mM), the pancreata were perfused with either 16.7 mM glucose (0-40 min) or with 20 mM arginine (0-20 min). Pancreastatin was introduced 10 min prior to and throughout the administration of the high glucose and arginine and continued during their perfusion. As expected, the glucose and the arginine augmented insulin and somatostatin release. Pancreastatin (1 and 10 nM) markedly suppressed the first phase of insulin release with both insulinogogues used, while the early somatostatin secretion was not significantly decreased. However, the peak incremental somatostatin response to arginine was reduced by 50% (P less than 0.05). Conversely, the peptide (10 nM) tended to augment arginine-induced glucagon release. Pancreastatin (100 nM) also suppressed glucose-stimulated insulin release from isolated rat islets. These pancreastatin-mediated alterations in islet hormone release are reminiscent of those known to characterize non-insulin-dependent diabetes. Therefore, the significance of pancreastatin in islet physiology and pathophysiology deserves special consideration.

Animals↗
PubMed1986

Iodinated derivatives of the vasoactive intestinal polypeptide (VIP) are agonists at the cat pancreas and the rat submandibular salivary gland.

Porcine VIP was iodinated by the chloramine-T method. The reaction products, which were separated by high pressure liquid chromatography, included residual native VIP, oxidized VIP and at least two iodinated VIP species. The iodo-VIP derivatives were recognized by antibodies raised against VIP and by VIP receptors. Furthermore, they appear to be approximately equipotent agonists to VIP in activating the adenylate cyclase in membranes from the rat submandibular salivary gland and in the stimulation of pancreatic secretion in vivo.

Adenylyl Cyclases↗
PubMed1986

Structural requirements for gastric inhibitory polypeptide (GIP) receptor binding and stimulation of insulin release.

The effect of bovine GIP 1-42 and several of its fragments in competing with the binding of 125I-GIP to beta-cell plasma membranes from transplantable hamster insulinoma, and in stimulating insulin release from the isolated perfused rat pancreas, was investigated. Our results, in association with the results of previous studies, indicate that the sequence 17-38 is necessary for receptor binding and biological activity of GIP. By contrast, the N-terminal portion of GIP can be removed without seriously impairing the activity of the molecule.

Animals↗
PubMed1986

Influence of beta-endorphin, somatostatin, substance P and vasoactive intestinal peptide on the proliferative response of human peripheral blood T lymphocytes to mercuric chloride.

The influence of beta-endorphin, somatostatin, substance P (SP) and vasoactive intestinal peptide (VIP) was tested on the proliferative response to mercuric chloride of human peripheral blood T lymphocytes, cultured for 5 days. When beta-endorphin, 10(-8) M, was added 1 h after mercuric chloride, there was an enhancement of the response, while a slight suppression was obtained with a 10(-6) M concentration of SP and VIP. When beta-endorphin, 10(-7)-10(-9) M, somatostatin, 10(-6)-10(-9) M, and SP, 10(-11)-10(-12) M, were added 3 days after mercuric chloride, they enhanced the response. At 10(-6) M, SP gave a suppressive effect.

Cell Division↗
PubMed1986

Modulating effect of beta-endorphin, somatostatin, substance P and vasoactive intestinal peptide on the proliferative response of peripheral blood T lymphocytes of nickel-allergic patients to nickel sulfate.

The influence of beta-endorphin, somatostatin, substance P (SP) and vasoactive intestinal peptide (VIP) was tested on the proliferative response of peripheral blood T lymphocytes of nickel-allergic subjects to nickel sulfate. With somatostatin, 10(-6)-10(-10) M, SP, 10(-9) and VIP, 10(-7)-10(-8) M, added 1 h after nickel sulfate, there was an enhancement of the response, while a slight suppression was obtained with SP, 10(-6) M. At 3 days after nickel sulfate, beta-endorphin, 10(-6)-10(-12) M, somatostatin, 10(-7)-10(-9) M and SP, 10(-7)-10(-11) M, gave an enhancement of the response.

Cells, Cultured↗