PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Bioactive peptides”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,243 records · Page 69Linked to original sources
PubMed1996

Interleukin 2 modulates intestinal epithelial cell function in vitro.

Although interleukin 2 (IL-2) has been presumed to have a highly circumscribed range of target cells limited largely to classic immune cell populations, the presence of functional IL-2 receptors in rat epithelial cell lines has recently been demonstrated. Limited information is available about the functional effects of IL-2 on intestinal epithelial cells. The effect of recombinant IL-2 on intestinal epithelial cell migration was assessed using a previously described in vitro model of epithelial restitution by quantitation of cells migrating into standard wounds established in confluent IEC-6 cell monolayers. Transforming growth factor beta content was assessed by Northern blot and bioassay. Exogenous IL-2 enhanced epithelial cell restitution in vitro on average 3.8-fold; this effect was independent of cell proliferation. Enhancement of restitution through IL-2 could be completely blocked through antibodies directed against TGFbeta1 and interleukin-2 receptor, indicating that stimulation of epithelial cell restitution is specifically enhanced by interleukin-2 and mediated through a TGFbeta-dependent pathway. In addition, increased expression of TGFbeta1 mRNA and increased levels of bioactive TGFbeta peptide in wounded monolayers treated with IL-2 compared to unwounded monolayers cultured in serum-deprived medium alone support the notion that enhancement of epithelial cell restitution in vitro is mediated through a TGFbeta-dependent pathway. These studies suggest that IL-2, a potent cytokine whose biological origin and targets have been presumed to be largely limited to lymphocyte and macrophage populations, may play a role in preserving the integrity of the intestinal epithelium following various forms of injuries.

Animals↗
PubMed1996

Two classes of metabolites from Theonella swinhoei are localized in distinct populations of bacterial symbionts.

The marine sponge Theonella swinhoei (lithistid Family Theonellidae, Order Astrophorida) has yielded many important, bioactive natural products, most of which share structural features with bacterial natural products. The presence of microbial symbionts in T. swinhoei has been reported, and it was originally suggested that the cytotoxic macrolide swinholide A and many of the bioactive cyclic peptides from T. swinhoei were all produced by simbiotic cyanobacteria. By transmission electron microscopy, we found four distinct cell populations to be consistently present in T. swinhoei: eukaryotic sponge cells, unicellular heterotrophic bacteria, unicellular cyanobacteria and filamentous heterotrophic bacteria. Purification and chemical analyses of each cell type showed the macrolide swinholide A to be limited to the mixed population of unicellular heterotrophic bacteria, and an anti-fungal cyclic peptide occurred only in the filamentous heterotrophic bacteria. Contrary to prior speculation, no major metabolites were located in the cyanobacteria or sponge cells.

Animals↗
PubMed1995

Quantitation of procholecystokinin and its products in plasma by processing-independent analysis.

A procedure for processing-independent quantitation of procholecystokinin (proCCK) and its products has been applied to plasma. The procedure is based on tryptic cleavage after Lys61 and Arg71 with subsequent monospecific radioimmuno-analysis of fragment 62-71 of human proCCK, which again corresponds to fragment 1-10 of CCK-22. The detection limit of the analysis was 0.2 pmol/l. Plasma was extracted with ethanol. In plasma from 13 healthy volunteers the basal concentration with the above-mentioned radioimmunoassay was 1.1 +/- 0.1 pmol/l (mean +/- S.E.M.) before, and 13.7 +/- 0.6 pmol/l after, incubation with trypsin. Two hours after ingestion of a mixed meal, the plasma concentration was 2.0 +/- 0.1 pmol/l before, and 21.7 +/- 1.2 pmol/l after tryptic cleavage. With a conventional CCK radioimmunoassay specific for the C-terminally amidated and O-sulfated bioactive epitope, the concentration was 1.0 +/- 0.1 pmol/l in the basal state and 4.2 +/- 0.4 pmol/l 2 h after a meal. Tryptic cleavage did not increase the concentrations of amidated, bioactive CCK peptides. In plasma from 37 patients with the carcinoid syndrome, the basal concentration of proCCK and its products was 14.1 (2.8-150.4) pmol/l (median (range)), compared with 0.3 (0-18.8) pmol/l for carboxyamidated CCK. Only two patients had significantly elevated CCK concentrations. We conclude that processing-independent analysis is useful for quantitation of proCCK and its products in plasma, since it quantitates CCK cell secretion more accurately than conventional CCK assays.

Adult↗
PubMed1990

Procholecystokinin processing in rat cerebral cortex during development.

Using a library of radioimmunoassays for essential sequences of procholecystokinin (proCCK), we have examined the post-translational processing in the rat cerebral cortex from fetal to adult state. The concentration of proCCK in the fetal cerebral cortex was 43 +/- 7 pmol/g tissue (wet weight; mean +/- S.E.M. (n = 20)). It remained constant until day 21 post partum, after which it decreased to undetectable levels. In contrast, the concentration of fully processed, bioactive CCK peptides (i.e. alpha-carboxyamidated CCK) rose from 2 +/- 1 pmol/g in the fetal cortex to 122 +/- 21 pmol/g in the adult. A particularly steep increase occurred from day 7 post partum (13 +/- 2 pmol/g) to day 21 (108 +/- 11 pmol/g). The concentration of glycine-extended intermediates rose gradually from 8 +/- 1 pmol/g in the fetal brain to 55 +/- 6 pmol/g in the adult. Gel chromatography of cortical extracts from day 7, 21 and 100 confirmed the variable processing at the C-terminal amidation site. The results show that the CCK gene is expressed as proCCK already in the fetal brain. However, the covalent modifications of proCCK follow different time courses so that only a small fraction reaches maturation until the first week post partum. We conclude that expression of transmitter-active CCK peptides in the brain is largely regulated at the post-translational rather than at the transcriptional level.

Aging↗
PubMed1992

Isolation and purification of N-formylmethionine aminopeptidase from rat intestine.

The intestinal mucosal epithelium is exposed to products of intestinal bacteria including potent inflammatory N-formylmethionyl oligopeptides. An N-formylmethionine aminopeptidase has been purified 2300-fold from rat intestine and was shown to degrade natural fMet oligopeptides from Escherichia coli culture supernatants with loss of bioactivity (release of specific granule constituents from human polymorphonuclear leucocytes) and immuno-reactivity (assessed using a polyclonal anti-fMet-Leu-Phe antiserum). The enzyme which was specific for N-terminal acyl-methionine residues had a native Mr of 340,000 and comprised four sub-units of Mr 82,000. The presence of this enzyme in intestinal mucosa could prevent absorption of intact bioactive fMet peptides produced by commensal bacteria in the gut lumen.

Amino Acid Sequence↗
PubMed1994

Isolation, sequence, and bioactivity of FMRFamide-related peptides from the locust ventral nerve cord.

The ventral nerve cord of the locust, Locusta migratoria, was examined for the presence of FMRFamide-related peptides (FaRPs). RP-HPLC coupled to an RIA specific for extended -RFamides revealed the presence of several FaRPs eluting at different percentages of acetonitrile. The sequences of five of these peptides were determined. Two sequences are identical to the two peptides previously sequenced from brain and retrocerebral complex of Locusta. These two peptides (PDVDHVFLRFamide and ADVGHVFLRFamide) were inhibitory when tested on locust oviduct contractions. The other peptides are novel with sequences of GQERNFLRFamide, AXXRNFIRFamide, and AFIRFamide. The synthesized peptides were stimulatory when tested on locust oviduct contractions, increasing the frequency and amplitude of spontaneous contractions and resulting in a basal contraction.

Amino Acid Sequence↗
PubMed1996

Production, analysis and bioactivity of recombinant vasoactive intestinal peptide analogs.

Recombinant vasoactive intestinal polypeptide (VIP) analogs were expressed in Escherichia coli as a fusion protein containing tandemly repeated multiple copies of a synthetic VIP gene joined to glutathione S-transferase. The encoded protein contains VIP units separated by a linker peptide, potentially excisable by a double cleavage with endoprotease factor Xa and hydroxylamine. Expression of different polyVIP genes, from 1 to 32 units, was detected and the production of a 16 VIP polymer was performed. MonoVIP analogs appended by 5 or 10 amino acids at their C terminus were released by factor Xa from this polymerized product. They were then submitted to hydroxylamine cleavage to remove the linker sequence to finally obtain a recombinant VIP analog devoid of any amino acid extension. The biological activity of the recombinant polyVIP and VIP analogs was tested. Although less efficient than the natural neuropeptide, some of these components bound to VIP receptor, activated adenylate cyclase in human colonic adenocarcinoma cells and displayed a relaxation activity on guinea pig tracheal rings.

Amino Acid Sequence↗
PubMed2005

Synthesis and bioactivities of two multiple antigen peptides as potential vaccine against schistosoma.

Based on the two antigenic peptides, 26-43 (P26) and 116-131 (P116), derived from 28 kDa glutathione S-transferase of Schistosoma mansoni (Sm28GST), two multiple antigenic peptides (MAPs), (P26)4-MAP and (P116)4-MAP with the same oligomeric lysine core, were synthesized by stepwise solid-phase peptide synthesis method. The antigenicities and protective effects of these two MAPs were examined on experimental animals. As shown in the dot-ELISA result, the synthetic MAPs could be recognized and bound by immunoglobins in both patient's and infected-rabbit's sera. After Kunming mice were immunized with (P26)4-MAP, the worm burden reduction rate and the liver egg reduction rate were 59.9% and 61.1%. In (P26)4-MAP or (P116)4-MAP immunized BALB/c mice, the worm burden reduction rates were 37.5% and 62.5%, respectively, and the liver egg reduction rates were 35.1% and 54.0%, respectively.

Amino Acid Sequence↗
PubMed2006

Intranasal administration of IGF-I improves behavior and Purkinje cell pathology in SCA1 mice.

Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by the expansion of polyglutamine repeat within ataxin-1 protein. Cerebellar Purkinje cells are the primary targets of SCA1 pathology. These cells synthesize insulin-like growth factor-I (IGF-I) and express its receptors during their entire life. The aim of present study was to determine if intranasally administered IGF-I to SCA1 transgenic mice suppresses toxic effects of ataxin-1. Two-week old SCA1 heterozygous animals were randomly divided into two treatment groups of IGF-I (30 and 60 microg IGF-I/animal) and a vehicle-treated control group. The wildtype animals served as normal controls. IGF-I or vehicle was administered at 48 h intervals for the total of 10 doses. Animals were then subjected to rotarod test, sacrificed, brains removed and processed for immunohistochemical and Western blot analysis. Radiolabeled IGF-I and bioactive TAT peptide accumulated in the brains of SCA1 mice following intranasal administration validating the use of intranasal route. SCA1 mice showed SCA1 pathology with impaired motor function and downregulation of calcium binding proteins as compared to wildtype mice. However, 30 and 60 microg IGF-I-treated animals showed improved performance on the rotarod as compared to vehicle-treated SCA1 mice with significant improvement (p < 0.05) on day 3 in 60 microg IGF-I group. The immunohistochemical data further showed partial recovery in the expression of calbindin D28k and protein kinase C-gamma in Purkinje cells in IGF-I-treated SCA1 animals. Our results indicate that suppression of ataxin-1-mediated adverse effects by intranasal IGF-I treatment may be of a therapeutic value to treat SCA1.

Administration, Intranasal↗
PubMed2005

Novel bioactive parathyroid hormone and related peptides in teleost fish.

We report the identification, gene expression and biological activity of two parathyroid hormones (PTH; PTHA and PTHB), two PTH-related peptides (PTHrP; PTHrPA and PTHrPB) and a PTH-like ligand (PTH-L) with hybrid characteristics in puffer fishes (Takifugu rubripes and Tetraodon fluviatilis). Experimental data are consistent with PTH-L and PTHrPA having calciotropic activities equivalent, respectively, to tetrapod PTH and PTHrP. We hypothesise on the basis of phylogenetic and functional analysis that PTH-L could be a fish relic of an ancestral PTH/PTHrP gene.

Amino Acid Sequence↗
PubMed2002

Guanylin and functional coupling proteins in the human salivary glands and gland tumors : expression, cellular localization, and target membrane domains.

Cystic fibrosis transmembrane conductance regulator (CFTR)-mediated secretion of an electrolyte-rich fluid is a major but incompletely understood function of the salivary glands. We provide molecular evidence that guanylin, a bioactive intestinal peptide involved in the CFTR-regulated secretion of electrolyte/water in the gut epithelium, is highly expressed in the human parotid and submandibular glands and in respective clinically most relevant tumors. Moreover, in the same organs we identified expression of the major components of the guanylin signaling pathway, ie, guanylin-receptor guanylate cyclase-C, cGKII, and CFTR, as well as of the epithelial Cl(-)/HCO(3)(-) anion exchanger type 2 (AE2). At the cellular level, guanylin is localized to epithelial cells of the ductal system that, based on its presence in the saliva, is obviously released into the salivary gland ducts. The guanylin-receptor guanylate cyclase-C, cGKII, CFTR, and AE2 are all confined exclusively to the apical membrane of the same duct cells. These findings implicate guanylin as intrinsic regulator of electrolyte secretion in the salivary glands. We assume that duct epithelial cells synthesize and release guanylin into the saliva to regulate electrolyte secretion in the ductal system by an intraductal luminocrine signaling pathway. Moreover, the high expression of guanylin in pleomorphic adenoma and Warthin tumors (cystadenolymphoma), the most common neoplasms of salivary glands, predicts guanylin as a significant marker in tumor pathology.

Adenolymphoma↗
PubMed2001

Synthesis and biological evaluation of pseudostellarin B.

A new potent bioactive cyclic peptide pseudostellarin B has been synthesised. The structure was elucidated by elemental analyses, IR, 1H NMR, 13C NMR and FAB mass spectral data. The synthesised compound was also screened for its antibacterial, antifungal, antiinflammatory and anthelmintic activities.

Animals↗
PubMed1998

Neutral endopeptidase-24.11 (NEP) activity in human fibroblasts during development and ageing.

Neutral endopeptidase-24.11 (NEP, EC 3.4.24.11) is a cell surface Zn metallopeptidase that hydrolyzes bioactive regulatory peptides. Using a spectrofluorimetric procedure, we assessed NEP activity in plasma membranes of normal human skin and lung fibroblasts. We found a considerable increase in NEP activity during fetal-to-adult transition. Adult skin fibroblasts from an old donor exhibited significantly higher levels of NEP activity than cells from young donors. Interestingly, however, the NEP activity of fibroblasts from a centenarian donor was similar to that of cells from young donors. Increased levels of NEP activity were also found in in vitro aged lung fibroblasts. Finally, adrenocorticotropin hormone (ACTH (1-24)), a regulatory peptide that can be cleaved by NEP, provoked an increase in enzymic activity in fetal and young adult donor fibroblasts and a decrease in this activity in fibroblasts from adult and old donors. This finding suggests that ageing may affect NEP activity.

Adult↗
PubMed1999

Kinin receptors are expressed in human astrocytic tumour cells.

Tissue kallikrein (TK) is known to be present in several tumours in which increased KLK1 (TK) gene expression has been demonstrated. By degrading components of the extracellular matrix, TK may facilitate tumour proliferation and invasion. The vasodilatory effect of the bioactive kinin peptides causes an increase in vascular permeability, thereby enhancing metastasis. Since kinins act by receptor-linked signal transduction mechanisms, the aim of this study was to elucidate the localization and expression of kinin B1 and B2 receptors in surgical samples of human astrocytic tumours. Tumour tissue collected was processed for light, confocal and electron microscopy (EM) and RNA extraction. The mean high intensity of immunolabeling in tumour cells was quantified in pixels per square micrometer using the Analysis 2.1 Prosystem (Soft-Imaging Software, Germany, 1996). The ultrastructural localization of B1 and B2 kinin receptors was performed on ultrathin sections of the resin-embedded tissue, using immunogold-labeled probes. In the human brain, immunoreactive B2 occurs in cortical neurones but not in glial cells, and immunolabeling for B1 receptors is absent in cortical areas. In the present study, in all of the tumours studied so far, immunolabeling for B2 (28.42 pixels/microm2, n = 12) and B1 (14.07 pixels/ microm2, n = 10) was observed on the astrocytic cells. Immunoreactive kinin receptors were also present in endothelial cells of the stromal blood vessels. At EM, the average number of immunogold particles was 14 for B2 receptors and eight for B1 receptors. The immunoreactive B2 receptors were located closer to the periphery of the tumour cells while B1 immunolabeling was observed throughout the cell.

Adolescent↗
PubMedDate not supplied

Structural identification of beta- and gamma-human atrial natriuretic polypeptides.

Atrial natriuretic polypeptides (ANPs) of varying chain length have been identified recently in human and rat atrial tissue. Their potent natriuretic-diuretic activities indicate their key role in the regulation of extracellular fluid volume and electrolyte balance. Furthermore, human and rat cDNAs encoding their precursor have been cloned and identified. Natriuretic-diuretic activity in human atrial extract comprises three distinct components (alpha, relative molecular mass (Mr) approximately 3,000; beta, Mr approximately 6,000; gamma, Mr approximately 13,000). However, only the 3,000-Mr peptide, alpha-human atrial polypeptide (alpha-hANP), comprising 28 amino acids, has so far been identified. We report here the purification and sequence analysis of two novel hANPs of higher Mr, beta- and gamma-hANP, both of which exhibit natriuretic and hypotensive activity. gamma-hANP, composed of 126 amino acids, carries the alpha-hANP sequence at its carboxy terminus. The identification of gamma-hANP reveals that the peptide, being the largest form of hANP, is processed directly from a 151-residue precursor by removal of a 26-residue signal peptide. In contrast, beta-hANP (56 residues) comprises an anti-parallel dimer of alpha-hANP; such a dimeric peptide possessing bioactivity has never been found in the tissue as an endogenous entity.

Amino Acid Sequence↗
PubMed2004

Guanylin regulates chloride secretion in the human gallbladder via the bile fluid.

BACKGROUND & AIMS: The biliary epithelium of bile ducts and gallbladder modifies the composition of primary hepatic bile by absorption and secretion of an electrolyte-rich fluid. The underlying transport mechanisms, however, are still incompletely understood. We investigated the expression, the cellular localization, and the functional role of guanylin, a bioactive intestinal peptide involved in the cystic fibrosis transmembrane conductance regulator (CFTR)-regulated electrolyte/water secretion, in the human gallbladder. METHODS: Peptide-specific antibodies were raised to localize guanylin and its affiliated signaling proteins, i.e., the guanylin receptor, guanylate cyclase C (GC-C), cGMP-dependent protein kinase type II (cGKII), and CFTR in the human gallbladder and cholangiocarcinoma cells (Mz-Cha-1) by RT-PCR, Western blot, and immunocytochemistry. A sensitive ELISA was used to assess the range of guanylin concentration in human bile fluid. The functional role of guanylin was investigated in subconfluent Mz-Cha-1 cell monolayers by isotope efflux experiments. RESULTS: Guanylin and its affiliated signaling proteins are highly expressed in the human gallbladder. Guanylin is localized to secretory epithelial cells of the gallbladder and is present in the bile, whereas GC-C, cGKII, and CFTR are confined exclusively to the apical membrane of the same epithelial cells. Functional studies in Mz-Cha-1 cells identify guanylin as a specific regulator of biliary Cl(-) secretion that very likely is mediated by an intracellular increase of cGMP-concentration. CONCLUSIONS: Based on the present findings and on the functional role of guanylin in other epithelia, it is likely that gallbladder epithelial cells synthesize and release guanylin into the bile to regulate electrolyte secretion by a paracrine/luminocrine signaling pathway.

Bile↗
PubMed2006

Health implications of milk containing beta-casein with the A2 genetic variant.

Milk from dairy cows has long provided a high quality source of protein and selected micronutrients such as calcium to most populations. Recently, a relationship between disease risk and consumption of a specific bovine ss-casein fraction either A1 or A2 genetic variants has been identified. Populations, which consume milk containing high levels of ss-casein A2 variant, have a lower incidence of cardiovascular disease and type 1 diabetes. Furthermore, consumption of milk with the A2 variant may be associated with less severe symptoms of autism and schizophrenia. The mechanism of action focuses on ss-casein A1 and related forms preferentially that are able to produce a bioactive opioid peptide, ss-casomorphin-7 (ss-CM-7) during digestion. Infants may absorb ss-CM-7 due to an immature gastrointestinal tract. Adults, on the other hand, appear to reap the biological activity locally on the intestinal brush boarder. ss-CM-7 can potentially affect numerous opioid receptors in the nervous, endocrine, and immune systems. Whether there is a definite health benefit to milk containing the A2 genetic variant is unknown and requires further investigation.

Adult↗