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Biomedical subjects

V Mutt

Publications and source records attributed to V Mutt.

At least 163 records · Page 9Linked to original sources
PubMed1980

The lung in relation to vasoactive polypeptides.

Among the metabolic functions of the lungs are the formation, release, activation and inactivation of biologically active peptides. The following peptides may be present or formed in normal lung: vasoactive intestinal peptide or a peptide closely related to it, a spasmogenic peptide not yet fully identified, bradykinin, substance P, a bombesin-like peptide (especially in fetal and neonatal lung), and eosinophil-chemotactic peptides. These peptides are found in special neuroendocrine cells, in neurons, or in mast cells. Normal lung also inactivates bradykinin and activates angiotensin; both processes are catalysed by the same enzyme (kininase II or angiotensin-converting enzyme), located in pulmonary vascular endothelium. Pulmonary tumours and certain non-tumorous lesions can produce and release a variety of peptide hormones that are not normally generated by the lung in substantial amounts. This 'ectopic' secretion of hormones may be detectable only by sensitive assays or may result in specific clinical syndromes.

Animals↗
PubMed1980

Vasoactive intestinal polypeptide in cholinergic neurons of exocrine glands: functional significance of coexisting transmitters for vasodilation and secretion.

By a combination of the indirect immunofluorescence technique with acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) staining, it was shown that vasoactive intestinal polypeptide (VIP) is present in cholinergic (acetylcholinesterase-rich) neurons involved in control of secretion and vasodilation in exocrine glands of cat. The submandibular salivary gland was used as a functional model. Preganglionic nerve stimulation induced an atropine-resistant, hexamethonium-sensitive vasodilation and release of VIP into the venous outflow from the gland and an atropine- and hexamethonium-sensitive secretion. Infusion of VIP antiserum reduced both the vasodilation and secretion. Infusion of VIP caused vasodilation only, whereas acetylcholine caused both vasodilation and secretion. Simultaneous infusion of VIP and acetylcholine in low doses resulted in a marked potentiation of both vasodilation and secretion. The present morphological and functional data support the following hypothesis for regulation of vasodilation and secretion in exocrine glands. Preganglionic cholinergic nerves activate, via nicotinic receptors, postganglionic neurons, causing concomitant release from the same nerve endings of two coexisting putative transmitters, acetylcholine and VIP. Acetylcholine produces mainly secretion by a muscarinic action and VIP causes mainly vasodilation, but the two substances seem to cooperate directly or indirectly in both types of response. Thus, the coexistence of two putative neurotransmitters, VIP and acetylcholine, in one neuron may explain the dual effector response (i.e., the cholinergic secretion and the atropine-resistant vasodilation) caused by nerve stimulation in exocrine glands.

Acetylcholinesterase↗
PubMed1980

Isolation and characterization of chicken secretin.

Chicken secretin has been isolated and its structure determined. It is composed of 27 amino acid residues, and has an amidated C terminus. The amino acid sequence is His-Ser-Asp-Gly-Leu-Phe-Thr-Ser-Glu-Tyr-Ser-Lys-Met-Arg-Gly-Asn-Ala-Gln-Val-Gln -Lys-Phe-Ile-Gln-Asn-Leu-Met-NH2. The structure shows distinct similarities to that of porcine secretin, amino acid identities occur at 14 positions (residues 1-4, 6-9, 11, 14, 17, 20, 24 and 26) but considerable differences are also present among the remaining 13 positions. Chicken secretin further shows a clear structural similarity to the vasoactive intestinal peptide (37% identical positions), the gastric inhibitory peptide (30% identical positions) and to glucagon (52% identical positions), suggesting wide evolutionary and functional relationships.

Amino Acid Sequence↗
PubMed1980

Entero-oxyntin: a stimulant of gastric acid secretion extracted from porcine intestine.

A peptide that further augments gastric acid secretion in cats, maximally stimulated by pentagastrin, was identified in porcine upper small intestine. Since the peptide stimulated basal and maximally pentagastrin-stimulated acid secretion to the same extent, it appears to act on a receptor different from the gastrin receptor and thus may be designated entero-oxyntin, a mediator of the intestinal phase of acid secretion.

Animals↗
PubMed1980

Cholecystokinin (pancreozymin). Synthesis and properties of the N alpha-acetyl-derivative of cholecystokinin 27-33.

The acetyl-derivative of the biologically active C-terminal 7-peptide portion of cholecystokinin (CCK), N-acetyl-O-sulfate-L-tyrosyl-L-methionyl-glycyl-L-tryptophyl-L-methionyl-L-aspartyl-L-phenylalanine amide was prepared by the condensation of 2-peptide segments with 1-isobutyloxycarbonyl-2-isobutyloxy-1,2-dihydroquinoline as coupling reagent. The N-terminal residue, tyrosine was incorporated by the active ester method. The same 7-peptide was prepared also by stepwise chain-lengthening, starting with the C-terminal residue. The 9-fluorenylmethyloxycarbonyl group was applied for the protection of alpha-amino functions. In the release of amylase from acinar cells of the pancreas of guinea pigs, the acetyl-7-peptide amide was about 3 times more potent than CCK 27-33 and equal in potency to CCK 26-33. The new derivative strongly stimulated the contraction of the in situ guinea pig gall bladder.

Amino Acid Sequence↗
PubMed1979

L-alanine--an essential amino acid for growth of lymphocytes in vitro.

A factor an ultrafiltrated (UM 10) extracts of calf thymus, liver and spleen stimulated the uptake of 3H-thymidine in DNA of cultured lymphocytes. The factor was purified by ion-exchange chromatography and gel chromatography and identified as alanine, which is lacking in the culture medium, RPMI 1640. An optimal amount of L-alanine increased the uptake of 3H-thymidine in DNA of lymphocytes from different species by about 100%. L-alanine should be regarded as a growth factor for lymphocytes in vitro and should be added to RPMI 1640, when this tissue culture medium is used for lymphocytes.

Alanine↗
PubMed1979

Localization and possible function of peptidergic neurons and their interactions with central catecholamine neurons, and the central actions of gut hormones.

The localization of various neuropeptides is described in the gut and in the hypothalamus in the rat. Evidence is given for the presence of material resembling corticotropin-like intermediate peptide in arcuate and periarcuate neurons, projecting to various hypothalamic nuclei, limbic areas and the thalamus. beta-Endorphin and glucagon decrease dopamine turnover in the median eminence, while secretin increases dopamine turnover and vasoactive intestinal polypeptide (VIP) has no effect. beta-Endorphin, VIP, secretin, and glucagon all produce discrete changes in norepinephrine turnover in various hypothalamic nuclei. Mainly increases of norepinephrine turnover were observed. These catecholamine turnover changes appear to cause changes in the secretion of prolactin and growth hormone. The results therefore indicate that gut hormones and opioid peptides may act directly on the hypothalamus on specific types of receptors to participate in the control of hypothalamic functions such as control of hormone secretion from the anterior pituitary and of food intake. It seems possible that gastrointestinal peptides released from the gastrointestinal tract into the circulation under certain circumstances could reach the hypothalamus and modulate its activity via the above-mentioned mechanisms. It may therefore be speculated that disturbances in gastrointestinal functions could lead to pathological changes in food intake via modulation of hypothalamic activity.

Adrenocorticotropic Hormone↗
PubMed1979

Some contributions to the chemistry of the gastrointestinal hormones.

Twenty-five years ago we described an extraction procedure for porcine secretin in which the intestinal tissue is briefly boiled in water and then extracted with dilute acid at low temperature. Boiling in water, which inactivates proteolytic enzymes, does not extract secretin, and extraction with acid in the cold will minimize cleavage of acid labile peptide structures. This extraction procedure has formed the basis for the isolation not only of secretin but also of cholecystokinin-pancreozymin (CCK) and, in collaboration with other laboratories, of the vasoactive intestinal peptide (VIP), the gastric inhibitory peptide (GIP), and motilin. Recently it has been used for the isolation of an N-terminally extended somatostatin from intestinal tissue, and of a peptide, from both nonantral gastric and intestinal tissues, with gastrin-releasing and probably cholecystokinin-releasing properties. A technique has been worked out permitting the chemical analysis, in certain cases, of polypeptide hormones in the presence of other polypeptides, the polypeptide mixture being exposed to fragmentation conditions known to result in characteristic hormone fragments, which are then extracted and quantitated. The technique can also be useful for the isolation of previously unknown peptides by identifying fragments of such and tracing them back to their peptides of origin.

Amino Acid Sequence↗