Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1573-6903
    Keywords: Synaptosome subpopulations ; coexistence ; co-release ; amino acids ; cholecystokinin ; vasoactive intestinal peptide ; somatostatin ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract GABAergic and cholinergic synaptosome populations were isolated by immunomagnetophoresis. Analysis of 8 amino acids showed that the GABAergic population was enriched in GABA (3 fold). The cholinergic population was enriched in citrulline (5 fold). CCK was found in both populations, but was enriched in the GABAergic. No monoamines were found in either subpopulation. Stimulated release (veratridine 50 μm), measured using a superfusion system, showed that glutamate was only released from the cholinergic subpopulation, as was VIP. In the GABAergic population, stimulated SRIF release was slow and prolonged, and the CCK release was delayed and rapid. GABA release was rapid, only occurring during application of the stimulus and only from the GABAergic synaptosomes. The GABAergic release could be modified by GABAA and GABAB targeted drugs. The cholinergic subpopulation exhibited late release of both VIP and CCK, each showing the same time pattern of release. All release was calcium and tetrodotoxin dependent.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0878
    Keywords: Thyroid ; Neuromedin U ; C-cell ; Immunocytochemistry ; Chromatography ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neuromedin U is a novel neuropeptide found to have a widespread distribution extending throughout the mammalian central nervous system, gastrointestinal tract and the endocrine cells of the pituitary gland. In order to investigate the possibility that neuromedin U-like immunoreactivity is also present in the thyroid gland of the adult rat we have examined its localisation and molecular nature by radioimmunoassay, immunocytochemistry and chromatographic analysis. The neuromedin U content of the whole thyroid gland was found to be 331±67 fmol/gland (mean±SEM), and this value significantly decreased (163±17 fmol/gland) as a result of 14 days of treatment with the anti-thyroid agent methimazole (10 mg/rat/day. Thyrotoxicosis induced by exogenous T4 (10 μg/rat/day) failed to alter the thyroid content of this peptide. Immunostaining studies localised neuromedin U to a minor population of parafollicular C-cells in untreated animals. Complementary chromatographic studies revealed a single molecular form of neuromedin U-like immunoreactivity in thyroid tissue extracts which was indistinguishable from synthetic rat neuromedin U standard.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of colonic infusion of various solutions on submaximal pentagastrin-stimulated gastric secretion was determined in healthy volunteers. Hypertonic (823 mOsm/kg) glucose, mannitol, and saline, and also isotonic glucose significantly induced a marked and sustained inhibition of gastric acid secretion of 74%, 66%, 79%, and 54%, respectively. A similar degree of inhibition was obtained for pepsin secretion with hypertonic glucose and mannitol. Isotonic triglycerides and isotonic saline solutions had no significant effect on gastric acid secretion. Hypertonic glucose, mannitol, and saline infusions significantly increased plasma concentrations of enteroglucagon, whereas other solutions had no effect. No correlation, however, was found between the percentage rise of enteroglucagon and the percentage inhibition of gastric secretion obtained from any of the three hypertonic solutions. The physiological significance of these findings remains to be established.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to assess the possible role of the new candidate gut hormone, motilin, in cantrolling the interdigestive migrating motor complex (MMC) in man, 14 normal subjects were studied after an overnight fast by means of three pressure-recording catheters with orifices 25 cm apart in the upper small intestine. The typical aboral progressing bursts of pressure waves occurred at a mean interval of 137 minutes and were preceded by a peak motilin level 25 pmol/liter higher than the lowest level in the postactivity-front quiescent period. To study the effect of exogenous motilin, an infusion of pure porcine motilin at various dose levels was given to 16 normal volunteers shortly after the onset of the phase I quiescent period. Motilin infusion induced an activity front in 12 of the 16 subjects. The mean activity front interval was reduced to 46 min (P〈0.001). This effect could be obtained tained even at the low dose level of 0.4 pmol/kg/min, which produced an increase in plasma motilin level of only 57 pmol/liter. These data suggest that a cyclic rise in plasma motilin levels is one of the factors involved in the production of the activity front of the migrating motor complex in man.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-2568
    Keywords: neuropeptide Y ; high pressure liquid chromatography ; lower esophageal sphincter ; 6-hydroxydopamine ; inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The quantitative distribution of neuropeptide Y (NPY) immunoreactivity has been determined along the length of the gastrointestinal tract in three mammalian species; rat, pig, and guinea pig. The peptide was shown to be present in all regions studied and in all three species. Exceptionally high concentrations were found in the region of the lower esophageal sphincter. Pretreatment of rats with 6-hydroxydopamine depleted NPY concentrations by 30–40%, indicating that NPY is colocalized in part with adrenergic nerves. Characterization of the NPY immunoreactivity by high-pressure liquid chromatography revealed a single major peak. NPY immunoreactivity derived from rat extracts eluted consistently earlier from the column than synthetic porcine standard, indicating minor species differences. Pharmacological studies using longitudinal muscle from guinea pig terminal ileum demonstrated that NPY caused a dose-dependent inhibition of the electrically stimulated, neurally mediated contraction of longitudinal smooth muscle. This suggested that NPY may act presynaptically to inhibit cholinergic transmission. The effects of various NPY fragments were also tested on the same preparation. The C-terminal fragments were active but were considerably less potent than NPY, while the free acid form of NPY and N-terminal fragment (1–19) were completely inactive. Thus, this study has demonstrated the presence of NPY in the gastrointestinal tract of various species, particularly within the lower esophageal sphincter. The pharmacological actions of the peptide suggest a role in the control of nonvascular smooth muscle tone.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-2568
    Keywords: gastrointestinal tract ; pancreas ; 7B2 ; radioimmunoassay ; gel chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution of a novel pituitary protein (7B2) was determined in the gastrointestinal tract and pancreas of four mammalian species (man, pig, guinea pig, and rat) by a specific radioimmunoassay. The highest concentrations of cross-reacting immunoreactive 7B2 (IR-7B2) were observed in the pancreas and the proximal gut (antrum or duodenum). While the intestinal concentrations varied widely among species, pancreatic IR-7B2 concentrations appeared to be similar in all four species. In the rat, pancreatic islets were found to contain high concentrations of IR-7B2 (5.73± 0.14 fmol/islet, mean± sem). Neonatal capsaicin treatment and enteric nerve section did not affect the concentrations of IR-7B2 in the rat intestine. Layer separation of human gut showed that IR-7B2 is mainly (71± 8%) present in the epithelial fraction. Chromatographic analysis of intestinal and pancreatic extracts from the four species on Sephadex G-100 showed the presence of two immunoreactive peaks at Kav 0.3 and 0.6, but there were both inter- and intraspecies variations in the proportions of the larger and smaller molecular forms.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1573-2568
    Keywords: cystic fibrosis ; gastrointestinal motility ; gut hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intestinal dysmotility may be an important factor contributing to various gastrointestinal complications associated with cystic fibrosis. Motilin, enteroglucagon, neurotensin, and peptide YY may each play a role as endocrine hormones influencing gastrointestinal motor activity. Fasting children with cystic fibrosis (N=8) and controls (N=18) received a liquid nutrient test meal (fat 4 g/100 ml, protein 4 g/100 ml, carbohydrate 20 g/100 ml, 125 kcal/100 ml; 200 ml/m2) containing lactulose (5 g/100 ml), and the plasma concentrations of these peptides were studied. Mouth-to-cecum transit time was simultaneously studied using the breath H2 technique. Fasting levels of peptide YY and the postprandial response of all four peptides were significantly increased in those with cystic fibrosis. In repeat studies on those with cystic fibrosis after a period of altered pancreatic enzyme supplementation, no significant changes in peptide concentrations were observed. A rise in breath H2 permitting estimation of mouth-to-cecum transit time was noted in 17 control subjects (70–220 min, median 140). In contrast, a rise occurred in only two with cystic fibrosis after low-dose enzyme (70 and 180 min), and four after high-dose enzyme replacement (120–230 min, median 155). Altered gut hormone secretion may play a role in the pathophysiology of intestinal dysmotility in patients with cystic fibrosis.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PHI (peptide histidine isoleucine) is a recently identified porcine peptide, present in large quantities in the intestine, which has sequence homologies with VIP, an established intestinal secretagogue, and with secretin, glucagon, and GIP. The effects of PHI on jejunal, ileal, and colonic fluid and electrolyte transport were studied in the pig. PHI appears to be an intestinal secretagogue inducing a reversible net secretion of fluid and electrolytes in jejunum and ileum and less marked effects in the colon.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of this study was to develop a radioimmunoassay for PHI and use this to assess its intramural distribution in the human intestine. The antibody was harvested following immunization with porcine PHI conjugated to bovine serum albumin by glutaraldehyde, and the iodinated PHI tracer was prepared by the Iodo-gen method. The assay system showed no cross-reaction with other members of the glucagon-secretin family of peptides and was sensitive to changes of PHI of 2 fmol/tube (95% confidence). High concentrations of immunoreactive PHI were found in the human intestine, exclusively localized in the nonendocrine gut layers, suggesting a possible neuroendocrinological or neurotransmitter role for PHI.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Luminal nutrients exert a powerful trophic effect on small bowel mucosa. Recent evidence suggests that a circulating factor, possibly enteroglucagon, is also growth-promoting. In order to study the isolated effect of nonluminal influences on bowel mucosa, Thiry-Vella fistulae (TVF) were constructed in rats. Circulating enteric hormone concentrations were manipulated by resecting different lengths of remaining gut. Thirty-two male Wistar rats had either 25%, 50%, 75%, or 90% proximal small bowel resection. In each animal the first 25% of resected bowel was exteriorized as a Thiry-Vella fistula. Seven control rats underwent jejunal transection. Twelve days postoperatively the fasted animals were killed, and circulating and tissue concentrations of enteroglucgon and CCK were estimated by radioimmunoassay. Crypt-cell production rate was used as an index of cellular proliferation in the Thiry-Vella fistulae. Proximal small bowel defunctioned in the Thirty-Vella fistulae had a significantly lower crypt-cell production rate and enteroglucagon and CCK content than the equivalent segment in transected rats. Further small bowel resection produced a subsequent increase in circulating enteroglucagon and CCK concentrations, an increase in the Thiry-Vella fistula content of these hormones, and a doubling of the crypt-cell production rate in the Thiry-Vella fistulae. These results show that circulating enteroglucagon and CCK concentrations match closely with enterocyte production even when luminal influences are excluded. It is suggested that circulating factors may play a major role in postresectional ileal hyperplasia. This hyperplasia apparently affects endocrine cells as well as enterocytes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...