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Biomedical subjects

C Vaillant

Publications and source records attributed to C Vaillant.

At least 73 records · Page 4Linked to original sources
PubMed1982

A rational approach to the fixation of peptidergic nerve cell bodies in the gut using parabenzoquinone.

Study of the possible chemical mechanisms by which parabenzoquinone acts as a fixative in the localisation of neuronal peptides by immunohistochemistry suggested several possible improvements to standard techniques. In particular, by using favourable conditions for regenerative oxidation reactions, i.e. fixing at 37 degrees C in well oxygenated, slightly alkaline buffer, it was possible to improve the localisation of substance P-, vasoactive intestinal polypeptide-, enkephalin- and somatostatin-like immunoreactive peptides such that nerve cell bodies were routinely visualised without the use of drugs to block axonal transport. Application of the improved fixation method is likely to facilitate study of the organisation of peptidergic systems.

Animals↗
PubMed1982

Distribution and development of peptidergic nerves and gut endocrine cells in mice with congenital aganglionic colon, and their normal littermates.

Studies were made of the distribution of gut hormones and neuropeptides in the gastrointestinal tract of mice with hereditary aganglionic colon (s1/s1) and their normal littermates. Antisera to substance P, vasoactive intestinal polypeptide, and enkephalins demonstrated markedly diminished numbers of immunofluorescent nerve fibers in the aganglionic segment of colon; in contrast, in proximal colon and small intestine the distribution of peptidergic nerve fibers was essentially normal. Mucosal endocrine cells were demonstrated in the colon by antisera to substance P, somatostatin, glucagon, and cholecystokinin; in each case there were similar numbers of cells in s1/s1 and normal mice. Radioimmunoassays for vasoactive intestinal polypeptide and bombesin showed diminished concentrations of immunoreactive material in the aganglionic segment of colon of 16-17-day-old animals. However, assays for CCK--which is predominantly located in endocrine cells--showed similar concentrations of immunoreactive material throughout the gut of s1/s1 and normal mice. It was of interest that the concentrations of immunoreactive substance P were lower than normal not only in the aganglionic segment of colon, but also in proximal colon and distal small intestine, and that at all ages the development of substance P in the intestine was delayed in the s1/s1 mice. The results are consistent with the idea that the constriction of the aganglionic segment of colon develops as a consequence of lack of intrinsic inhibitory neurons, possibly those containing vasoactive intestinal polypeptide. The presence of an aganglionic segment is attributable to delayed migration of the neuroblasts from the neural crest. Thus the findings of normal populations of gut endocrine cells in the aganglionic segment is further support for the view that the embryologic origin of gut endocrine cells is different to that of gut neurons.

Animals↗
PubMed1981

Vertebrate brain-gut peptides related to FMRFamide and Met-enkephalin Arg6Phe7.

Many mammalian brain-gut peptides are known to be represented in invertebrate nervous systems; we have now examined the possibility that an invertebrate neuropeptide occurs in vertebrates. Antisera were raised in rabbits to the molluscan neuropeptide. Phe-Met-Arg-Phe-NH2 (FMRFamide). The antiserum used for radioimmunoassay and immunocytochemistry is highly specific for the C-terminus of the tetrapeptide. In radioimmunoassays of tissue extracts of brain, gut and pancreas of various vertebrates (chicken, frog, dog, rat) concentrations of immunoreactive material up to about 200 pmol/g have been recorded. The immunoreactive material in chicken pancreas behaves on gel filtration and ion exchange chromatography as a molecule that is larger and less basic peptide that FMRFamide. Immunocytochemical studies have demonstrated an endocrine cell origin for FMRFamide-like material in chicken pancreas, and in dog ileum. In brain, FMRFamide can be localised to nerve cell bodies (frog) and nerve fibres (frog and rat). Synthetic FMRFamide has been shown to have excitatory actions on brain stem neurons in the rat. It is suggested that neurons in the rat central nervous system have receptors for FMRFamide that normally bind endogenous material with FMRFamide immunoreactivity.

Animals↗
PubMed1981

Demonstration of carboxyl-terminal PP-like peptides in endocrine cells and nerves.

Pancreatic polypeptide (PP) has been isolated from the pancreas of several species, and has been localized by immunohistochemistry to a distinct population of pancreatic endocrine cells. Recently, PP-like immunoreactivity has been demonstrated outside the pancreas, in gut endocrine cells and central and peripheral nerves, in studies using antisera raised to natural PPs. The antigenic determinants recognised by these antisera are not known in any detail, and, therefore, the identity of the molecules in these extrapancreatic localizations is also unknown. We have raised an antiserum to the synthetic COOH-terminus of PP (PP6), which, therefore, is directed exclusively towards the biologically active, invariant region of mammalian PPs. PP6-like immunoreactivity was localized in pancreatic cells which were revealed also by antiserum to human PP (hPP). Outside the pancreas, no localizations were obtained with anti-hPP antiserum, whereas antiserum to PP6 demonstrated immunoreactivity in a variety of tissues including gut glucagon cells, adrenal chromaffin cells, and nerve fibres in the gastrointestinal tract and adrenal gland. We would suggest that the wide distribution in nerves and endocrine cells of PP6-immunoreactive material, which may be biologically active, should be taken into account in the search for a physiological role for PP.

Adrenal Glands↗
PubMed1981

Family studies of hypergastrinemic, hyperpepsinogenemic I duodenal ulcer.

Antral G-cell hyperfunction is a rare cause of hypergastrinemia, hyperchlorhydria, and duodenal ulcer disease. We found evidence for a familial basis for this disorder. The probands were two young men with aggressive duodenal ulcer who had basal and postprandial hypergastrinemia, hyperpepsinogenemia I, and basal and pentagastrin-stimulated hyperchlorhydria. All characteristics returned to normal after antrectomy and vagotomy. Antral gastrin concentrations and quantitative G-cell counts were normal, indicating hyperfunction of G-cells rather than hyperplasia. Four of 10 first-degree relatives of the two patients shared with them the combination of postprandial hypergastrinemia and hyperpepsinogenemia I. The aggregation of these abnormalities in tow families, each identified by a proband with hypergastrinemic, hyperpepsinogenemic l duodenal ulcer, suggests that antral G-cell hyperfunction may have a genetic basis.

Adolescent↗
PubMed1980

The distribution and cellular origin of vasoactive intestinal polypeptide in the avian gastrointestinal tract and pancreas.

The distribution and origins of vasoactive intestinal peptide (VIP) in the gut and pancreas of the turkey were studied by radioimmunoassay of tissue extracts and by immunocytochemistry. Several antisera were used that vary in their specificity for different regions of porcine or chicken VIP. Radioimmunoassays using NH2-terminal specific antisera that react almost equally with porcine and chicken VIP's revealed signficant amounts of immunoreactive VIP in extracts of pancreas, brain and all regions of the gastrointestinal tract from crop to colon. Highest concentrations (300 pmol/g) were found in the colon muscle, and concentrations were generally low (< 20 pmol/g) in the mucosal layers of the small intestine. After ion exchange chromatography of extracts on CM-Sephadex three immunoreactive forms of VIP were separated corresponding to the three molecular forms previously found in mammalian gut extracts. In immunocytochemical studies nerve fibres were found throughout the gut, and in the pancreas. Immunoreactive nerve cell bodies were also identified in the submucous plexus throughout the gut, but were particularly prominent in the oesophagus and pancreas. It has previously been shown that VIP is a strong stimulant of the flow of pancreatic juice in birds whereas the structurally related hormone secretion, which is known to control the flow of pancreatic juice in mammals, is a weak stimulant. It is proposed that in birds VIP might regulate the pancreas, and other aspects of gut function, as a neurotransmitter or neurohormone.

Animals↗
PubMed1979

The avian proventriculus is an abundant source of endocrine cells with bombesin-like immunoreactivity.

Radioimmunoassays using specific bombesin antisera revealed high concentrations of immunoreactivity in the turkey proventriculus, and negligible amounts of activity elsewhere in the gut. In immunohistochemical studies the same antisera revealed abundant endocrine-like cells in proventriculus mucosa, and isolated cells in small intestinal mucosa. In contrast to the rat, immunoreactivity was not demonstrated in nerves.

Animals↗
PubMed1979

Cellular origins of different forms of gastrin. The specific immunocytochemical localization of related peptides.

We have localized the antigenic determinants for the main forms of gastrin (big gastrin, G34, and little gastrin, G17) in hog antral mucosa using sequence specific antibodies and an indirect immunofluorescence technique. Populations of monospecific antibodies were obtained after affinity immunoadsorption to remove populations of unwanted specificity. The specificity of the purified antisera was established by direct binding of 125I labeled peptides to antisera at the same dilutions as those used in immunocytochemistry. The results indicate that in hog antral mucosa there is a single population of cells with the antigenic determinants of the C-terminal region of G17 and G34, the N-terminal region of G17, the N-terminal region of G34, and the intact G17 molecule. In duodenum there are cells with only C-terminal reactivity; since gastrin and CCK share a common C-terminal sequence it is concluded that this cell type contains CCK-like peptides rather than gastrin.

Animals↗