Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INTESTINAL SECRETIONS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65Linked to original sources
PubMed1983

Free amino acid concentrations in the gut lumen of developing rats.

Free amino acid concentrations in the lumen and tissue of small intestine of suckling rats were measured by a micromethod. Almost all amino acid concentrations (Lys excepted) in the intestinal juice decrease until 15 days of age whereby the pattern remains constant. Concomitantly, free amino acid concentrations in the intestinal tissue increase between 10 and 15 days p.p. The pool of amino acids in the intestinal juice, reflecting the nutritional input and its utilization, becomes exhausted during the suckling period. At 20 days of age the rats additionally ate the rat chow and free amino acid concentrations in the intestinal tissue increased again. The decline of the amino acid pool in the lumen of small intestine which is both derived by the mother and exhausted by the growing organism may act as a signal for differentiation via (self-) restriction of substrates for protein accretion.

Amino Acids↗
PubMed1987

Naloxone-reversible antidiarrheal effects of enkephalinase inhibitors.

Thiorphan and acetorphan, two potent inhibitors of enkephalinase (EC 3.4.24.11 membrane-metalloendopeptidase) significantly reduced the castor oil-induced diarrhea in rats when administered intravenously (or orally, for acetorphan) but not when administered intracerebroventricularly. These effects were more marked during the 90 min period following the castor oil challenge but were still significant up to 4-8 h after the latter. Acetorphan was about 6 times more potent than thiorphan. The antidiarrheal activity of both compounds was completely prevented in rats receiving naloxone subcutaneously but not intracerebroventricularly (in the case of thiorphan). In contrast to loperamide, a peripherally acting opiate receptor agonist, the enkephalinase inhibitors did not significantly reduce gastrointestinal transit as measured in the charcoal meal test. The antidiarrheal activity of enkephalinase inhibitors therefore seems attributable to protection of endogenous opioids, presumably outside the brain, and to reduction of intestinal secretion rather than transit.

Amino Acids, Sulfur↗
PubMed1990

Carbachol mimics phorbol esters in its ability to enhance cyclic GMP production by STa, the heat-stable toxin of Escherichia coli.

STa, the heat-stable enterotoxin of Escherichia coli, stimulates membrane-bound guanylate cyclase in enterocytes, elevates cyclic GMP, and results in intestinal secretion of ions and fluid. Using the T84 colon carcinoma cell line as a model. Weikel et al. reported that phorbol esters enhance STa-stimulated cyclic GMP production by 60-140% [(1990) Infect. Immun. 58, 1402-1407]. In the present report we demonstrate that the acetylcholine analog carbachol enhanced toxin-stimulated cyclic GMP accumulation in intact T84 cells by 50-100% and that this effect was blocked by 10 microM atropine and 10 microM sphingosine. Pertussis toxin treatment of the T84 cells did not affect the subsequent response to carbachol. Carbachol, which elevates intracellular calcium in these cells, may act through protein kinase C to enhance cyclic GMP production.

Animals↗
PubMed1986

Evidence of local mechanism involvement in vasoactive intestinal polypeptide release from canine small intestine.

We studied the effect of intraileal administration of a 100-ml test meal, 100 ml of 5% glucose, amino acids, 10% Intralipos, or bile on canine plasma immunoreactive vasoactive intestinal polypeptide (VIP) levels in the mesenteric and femoral veins of dogs. The effects of intravenous administration of caerulein on plasma immunoreactive VIP levels were examined, with or without intraduodenal ballooning, to rule out the effect of bile and pancreatic and gastric juice. In addition, hexamethonium bromide or atropine sulfate was given intravenously before the administration of bile or intravenous caerulein to study the role of the neural pathway on the release of VIP. Basal plasma VIP levels in the mesenteric vein were significantly higher than those in the femoral vein. Intraileal administration of the test meal, 5% glucose, amino acids, or 10% Intralipos induced no variation of mesenteric VIP. Intraileal administration of bile or intravenous caerulein, with or without intraduodenal ballooning, produced a significant increase of plasma VIP in the mesenteric vein. Pretreatment with atropine completely blocked the bile-stimulated VIP release and significantly inhibited the caerulein-stimulated release of VIP. On the other hand, pretreatment with hexamethonium did not significantly decrease the VIP response by bile or caerulein. Thus, the muscarinic receptor probably plays an important role in bile- or caerulein-stimulated release of VIP.

Amino Acids↗
PubMed1988

A rapid and sensitive screening method for the detection of anti-2-acetylaminofluorene immunoglobulins.

A method is described in which anti-2-acetylaminofluorene immunoglobulins may be detected using a simple and sensitive screening procedure. The method is based on immunoglobulin binding of an 125I derivatized 2-aminofluorene radiotracer. Tracer binding is not isotype specific, and thus the method is useful for the detection of either IgG or IgA. Competitive binding experiments with the radiotracer were used to determine the specificity of immunoglobulin response by measurement of cross-reactivity with related ligands. This method allows quantitation of the immune response to the carcinogen in serum and other biological fluids (i.e., intestinal secretions).

2-Acetylaminofluorene↗
PubMed1990

Treatment of endocrine and nonendocrine secretory diarrheal states with Sandostatin.

Endocrine tumors of the gastroenteropancreatic (GEP) axis elaborate excessive amounts of peptides that are potent intestinal secretagogues. The actions of these peptides on intestinal transport of water and electrolytes lead to the accumulation of fluid in the intestinal lumen and diarrhea. One of the most clinically relevant secretagogues is vasoactive intestinal polypeptide (VIP). Other relevant secretagogues elaborated from tumors are serotonin, prostaglandins, and kinins. Sandostatin (octreotide, Sandoz, Basle, Switzerland), a long-acting octapeptide analog of somatostatin, inhibits experimentally induced intestinal secretion and has been used successfully to treat patients with secretory diarrhea refractory to other pharmacotherapy. The effective dose is in the range of 50 to 200 micrograms, given subcutaneously two or three times daily. The mechanism for the inhibitory effect on secretion is not clearly understood but it appears to involve inhibition of the adenylate cyclase-cyclic adenosine monophosphate system as well as interference with calcium as an intercellular mediator of enterocyte secretion. A particularly interesting use of this drug has been to treat the watery diarrhea seen in patients with acquired immunodeficiency syndrome. It is also effective in other types of secretory diarrhea not associated with endocrine tumors. These include diabetic diarrhea, idiopathic secretory diarrhea of infancy, and high output ileostomy diarrhea.

Acquired Immunodeficiency Syndrome↗
PubMed1976

Enteropooling assay: a test for diarrhea produced by prostaglandins.

An assay (enteropooling assay) to test the diarrheogenic property of prostaglandins is described. Fasted rats are given a prostaglandins either orally or subcutaneously, and are killed 30 min later. The entire small intestine is removed and its contents collected into a test tube. The greater the volume of this intestinal fluid, the more diarrheogenic is the prostaglandin. The assay is simple, rapid, quantitative, and predictive of diarrhea. It can be used to grade the relative diarrhoegenic activity of prostaglandins as well as to test agents that may block this effect. The accumulation of fluid into the small intestine is called "enteropooling". It is the sum of (a) the fluid being excreted from the blood into the lumen, and (b) to a lesser extent, the portion of fluid already into the lumen but whose absorption is inhibited by the prostaglandin. The degree of enteropooling depends also on how much fluid flows from the small to the large intestine. Our results support the hypothesis that the diarrhea observed after administration of high doses of prostaglandins is due to accumulation of abundant fluid into the small intestine, and not intestinal hypermotility. This fluid is then carried into the large intestine and eventually expelled as diarrhea. Agents other than prostaglandins were tested for enteropooling activity. Laxatives such as castor oil, hypertonic solutions and bile salts caused enteropooling.

Animals↗
PubMed1990

Cecectomized rat. A model of experimental secretory diarrhea in conscious animals.

Evaluation of antisecretory antidiarrheal agents in animal models is limited primarily to extrapolations of efficacy from enteropooling studies in vivo, isolated intestinal loops in situ, and Ussing flux chamber preparations in vitro. While these standard techniques are useful, they do not mimic secretory diarrhea. Our studies indicate that in rats, the cecum may serve a "reservoir" function in response to secretagogue administration. Thus, diarrhea is not observed consistently and reliably in this species to allow valid evaluation of potential antidiarrheal agents. Therefore, we have developed a reproducible model of secretory diarrhea utilizing conscious cecectomized rats by surgical resection of the cecum, without compromising ileocecal patency, and by the use of potent intestinal secretagogues. Animals quickly recover and maintain normal growth and other physiologic parameters for as long as 60 days. After 48 hr on standard chow, secretory diarrhea can be induced by oral administration of standard intestinal secretagogues (dimethyl prostaglandin E2, cholera toxin, or carbachol). Dimethyl prostaglandin E2 (300 micrograms/kg, p.o.) induces diarrhea within 1 hr that continues for approximately 3.5 hr. Oral administration of known antidiarrheal agents chlorpromazine (10 mg/kg), clonidine (1 mg/kg), or morphine (10 mg/kg) all significantly reduce fecal output within 30-60 min following administration. These studies indicate that in the rat, the cecum may serve as a fluid reservoir during periods of small intestinal hypersecretion and that the cecectomized rat serves as a useful, accurate, and reliable tool for evaluating new compounds with proposed antidiarrheal activity.

Animals↗
PubMed1980

Intestinal immunity following a single intraperitoneal immunisation in lambs.

A single intraperitoneal injection of ovalbumin in oil adjuvant in young lambs has been shown to result in the appearance in the intestinal lamina propria of antibody-containing cells, most of which contained antibody of IgA specificity. Intraperitoneal immunisation of lambs with a Salmonella typhimurium vaccine during the suckling period provided protection against postweaning challenge with live organisms. This response was shown to be associated with specific IgA antibody in intestinal secretion.

Animals↗
PubMed1994

Epitopic analysis of the Toxoplasma gondii major surface antigen SAG1.

T and B cell epitopes of the major Toxoplasma gondii surface antigen SAG1 were studied following CNBr fragmentation. Three fragments, F1, F2 and F3, were obtained, of 19, 16.5 and 14 kDa, respectively. The positions of F1 F2 and F3 within the SAG1 protein were identified by N-terminal sequence determination. The F1 fragment located on residues 125-269 contains the C-terminus, and the fragment F2 (residues 1-124) is located at the N-terminal region. F3 is a C-terminal peptide about 40 amino acids shorter than the F1 fragment (residues 165-269). Polyclonal antibodies obtained from infected animals or humans and a monoclonal anti-SAG1 antibody did not recognize either the reduced protein or the reduced fragments on immunoblotting. The monoclonal antibody 1E5 did not recognize fragment F1. Mouse IgA and IgG antibodies from infected mouse sera and intestinal secretions, as well as human IgG antibodies, only recognized the whole protein and the F1 fragment. These results suggest that the fragment F1 encompasses all B cell epitopes recognized on the SAG1 protein after infection with the parasite and that the sequence 125-165 is essential for the structural integrity of these B cell epitopes. Murine anti-SAG1 T cell proliferation was observed in SAG1 immunized CBA/J mice (H-2k) and BALB/c mice (H-2d), but not in C57BL/6 mice (H-2b). The three fragments F1, F2 and F3 were able to induce specific proliferation of anti-SAG1 T cells from CBA/J mice, while only the F1 and F2 fragments induced specific blastogenesis of anti-SAG1 T cells from BALB/c mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1996

A continuous epitope from transmissible gastroenteritis virus S protein fused to E. coli heat-labile toxin B subunit expressed by attenuated Salmonella induces serum and secretory immunity.

Antigenic site D from the spike protein of transmissible gastroenteritis virus (TGEV), which is a continuous epitope critical in neutralization, has been expressed as a fusion protein with E. coli heat-labile toxin B subunit (LT-B) in attenuated S. typhimurium. Synthetic peptides containing the sequence of site D induced TGEV neutralizing antibodies when inoculated subcutaneously in both rabbits and swine. A synthetic oligonucleotide encoding residues 373-398 of TGEV S protein, including antigenic site D, was cloned in frame with the 3' end of LT-B gene, into a plasmid used to transform S. typhimurium delta asd chi 3730. A collection of 6 recombinant plasmids designated pYALTB-D I-VI encoding LTB-site D fusions with a variable number of site D sequences were selected. Four of the 6 LTB-site D fusion products expressed in S. typhimurium chi 3730 formed oligomers (pentamers) that dissociated at > 70 degrees. S. typhimurium chi 3730 (pYALTB-D) V and VI expressed the oligomer forming products with higher antigenicity. Partially purified LTB-site D fusion product expressed from S. typhimurium chi 3730 (pYALTB-D) V induced anti-TGEV neutralizing antibodies in rabbits. Recombinant vaccine strain S. typhimurium delta cya delta crp delta asd chi 3987 transformed with plasmid pYALTB-D V expressed constitutively products that formed oligomers presumably containing 20 copies of site D, and showed a high stability in vitro. This recombinant strain was orally inoculated in rabbits and induced TGEV specific antibodies in both serum and intestinal secretion.

Amino Acid Sequence↗
PubMed1996

The pathogenesis of cryptosporidiosis.

Human infection with the protozoan parasite Cryptosporidium parvum has recently emerged as a global public health problem. Although infection is unrelenting in patients classically regarded as immunocompromised, a tantalizing observation is that infection with this parasite results in both acute self-limited as well as chronic diarrhea in young children. Recent data have begun to elucidate multiple potential mechanisms by which parasitism of the intestinal epithelium may yield an intestinal secretory response. However, a central issue for future studies is to understand how Cryptosporidium infection in young children results in such a broad spectrum of clinical presentation. An answer to this question is likely to result through a dual understanding of how systemic or enteric immunity impacts on intestinal secretory responses and how intra-cellular parasitism alters intestinal epithelial cell function and signals the submucosal intestinal compartment. The virulence factors of Cryptosporidium mediating these events need to be identified. Douglas Clark and Cynthia Sears here review the current understanding of the pathogenesis of intestinal secretion in response to Cryptosporidium infection, and discuss key questions requiring additional study.

Journal Article↗
PubMedDate not supplied

BCG-induced mucosal immune responses.

The induction of mucosal immune responses is particularly important for protection against diseases for which entry and pathogenesis are clearly related to the mucosal system, such as salmonellosis, AIDS or tuberculosis. We investigated the immune responses in guinea-pigs vaccinated by BCG via the respiratory compared to the intradermal route. The results demonstrate that the aerogenic BCG induced a better activation of broncho-alveolar macrophages and a substantially improved protective effect against a virulent challenge with Mycobacterium tuberculosis. We also used a DNA recombinant BCG expressing LacZ gene to investigate the influence of various routes of administration on the immunogenicity of the beta-galactosidase, a foreign antigen expressed by the LacZ-BCG recombinant. Thus, lymph-node proliferative responses, delayed type hypersensitivity and antibody responses specific for beta-galactosidase can be produced in guinea-pigs immunized orally, respiratorily and intradermally. The respiratory and especially the oral route of administration produced higher mucosal and systemic immune responses compared with the intradermal route of immunization. Moreover, the oral immunization of mice with recombinant BCG induced IgA responses which can be detected both in sera and in intestinal secretions. In conclusion, BCG recombinants may be of potential use as an adjuvant vaccine.

Animals↗