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At least 199 records · Page 11Linked to original sources
PubMed2003

Characterization of beta-lactotensin, a bioactive peptide derived from bovine beta-lactoglobulin, as a neurotensin agonist.

beta-Lactotensin (beta-LT: His-Ile-Arg-Leu) is an ileum-contracting peptide derived from residues No. 146-149 of bovine beta-lactoglobulin. The ileum-contracting activity of beta-LT was blocked by the NT1 antagonist SR48692. beta-LT was selective for the neurotensin NT2 receptor while neurotensin was selective for the NT1 receptor. beta-LT is the first natural ligand showing selectivity for the NT2 receptor. beta-LT showed hypertensive activity after intravenous administration at a dose of 30 mg/kg in conscious rats, while neurotensin showed hypotensive activity. The hypertensive activity of beta-LT was blocked by levocabastine (1 mg/kg, i.v.), an NT2 antagonist. SR48692, which blocked the hypotensive activity of neurotensin, had no effect on the hypertensive activity of beta-LT. These results suggest that the hypertensive activity of beta-LT is mediated by the NT2 receptor. It was concluded that the NT1 and NT2 receptors mediate the opposite effect on blood pressure.

Animals↗
PubMed1993

Ectopic expression of bioactive peptides and serotonin in the sacciform gland cells of teleost skin.

Immunohistochemical methods identified serotonin, and the peptides bombesin and caerulein, in the skin of the teleosts Lepadogaster candollei and Mastacembelus erytrotaenia. In both species, the secretory content of epidermal sacciform cells reacted positively for all three substances. These results are compared with studies on the skin glands of amphibians, which also contain multiple active compounds, and on various neuroendocrine cells of fish. The precise functions of the secretions are not known.

Animals↗
PubMed2005

Animal models of central nervous system immune-mediated diseases: therapeutic interventions with bioactive peptides and mimetics.

Experimental allergic encephalomyelitis (EAE) is a T helper 1 (Th1) mediated autoimmune disease and the principal animal model for multiple sclerosis (MS). Like MS, EAE is characterized by a coordinated inflammatory attack on the myelin sheath in the central nervous system (CNS), with damage to axons. No matter whether the ideal animal model is not yet available, much knowledge concerning the pathogenesis of MS has been achieved through studies on EAE. Dissecting the underlying immune mechanisms provided recognition of several myelin antigens that are vulnerable in autoimmune attack. The beneficial effect and the mechanism of action of a number of the currently used immunomodulating agents in MS therapy were first indicated in EAE. Altered peptide ligands (APL) can modulate T-cell responses to native peptide antigens implicated in the pathogenesis of autoimmune diseases such as MS and EAE. However, peptide therapy is hindered due to the sensitivity of peptides to proteolytic enzymes as well as due to some immune-mediated side effects. A number of cyclic myelin peptide analogs seem to be potential candidates in maintaining the biological function of the original peptide and effective in controlling inflammation in EAE. Additional data regarding the immunomodulating and neuroprotective effect of these much promising agents is required. Based on the data from studies on EAE models, clinical trials should also be designed in order to elucidate the impact of such APL-induced immune responses in MS disease activity. These clinical trials should carefully incorporate monitoring of both clinical, neuroimaging and immunological parameters.

Animals↗
PubMed2005

A yeast extract high in bioactive peptides has a blood-pressure lowering effect in hypertensive model.

It was reported that angiotensin-converting enzyme (ACE) plays an important role in increasing blood pressure. Recently, it was reported that several food hydrolysates have ACE inhibitory effects in the spontaneous hypertensive rat (SHR) model and mildly hypertensive subjects. Therefore, the anti-hypertensive effects of brewer's yeast BY-G were investigated, which contains many kinds of beneficial nutrients (vitamins, minerals, nucleic acids, glutathione, amino acids, etc.). The aim of this study was to evaluate the anti-hypertensive effects of BY-G and its component peptides obtained by enzymatic treatment. The peptide fraction KRF814 was obtained by the hydrolysate of BY-G with alkaline protease and then treated with Amberlite XAD-2. The KRF814, which has an inhibitory effect on ACE in vitro, was obtained. BY-G and KRF814 were fed to male SHR and showed significantly anti-hypertensive effects. KRF814 contained alanyl-phenylalanine (AF) and glycyl-phenylalanine (GF), which significantly decreased systolic BP in the SHR model. The active ingredients of KRF814, AF, and GF had about 60% of the potency of the positive control, which was captopril. It is considered that intake of BY-G or its component peptides as a functional food stuff might be beneficial for improving BP in people with hypertension.

Animals↗
PubMed2001

Delivery of bioactive peptides and proteins across oral (buccal) mucosa.

The identification of an increasing array of highly potent, endogenous peptide and protein factors termed cytokines, that can be efficiently synthesized using recombinant DNA technology, offers exciting new approaches for drug therapy. However, the physico-chemical and biological properties of these agents impose limitations in formulation and development of optimum drug delivery systems as well as on the routes of delivery. Oral mucosa, including the lining of the cheek (buccal mucosa), floor of mouth and underside of tongue (sublingual mucosa) and gingival mucosa, has received much attention in the last decade because it offers excellent accessibility, is not easily traumatized and avoids degradation of proteins and peptides that occurs as a result of oral administration, gastrointestinal absorption and first-pass hepatic metabolism. Peptide absorption occurs across oral mucosa by passive diffusion and it is unlikely that there is a carrier-mediated transport mechanism. The principal pathway is probably via the intercellular route where the major permeability barrier is represented by organized array of neutral lipids in the superficial layers of the epithelium. The relative role of aqueous as opposed to the lipid pathway in drug transport is still under investigation; penetration is not necessarily enhanced by simply increasing lipophilicity, for other effects, such as charge and molecular size, also play an important role in absorption of peptide and protein drugs. Depending on the pharmacodynamics of the peptides, various oral mucosal delivery systems can be designed. Delivery of peptide/protein drugs by conventional means such as solutions has some limitations. The possibility of excluding a major part of drug from absorption by involuntary swallowing and the continuous dilution due to salivary flow limits a controlled release. However these limitations can be overcome by adhesive dosage forms such as gels, films, tablets, and patches. They can localize the formulation and improve the contact with the mucosal surface to improve absorption of peptides and proteins. Addition of absorption promoters/permeabilizers in bioadhesive dosage forms will be essential for a successful peptide/protein delivery system.

Animals↗
PubMed2006

Bioactive peptides in ovine and caprine cheeselike systems prepared with proteases from Cynara cardunculus.

The potential angiotensin-converting enzyme (ACE)-inhibitory and antioxidant activities of peptides in water-soluble extracts, obtained from raw and sterilized ovine and caprine cheeselike systems coagulated with enzymes from the plant Cynara cardunculus, were assessed. Prior to the assay, the 3,000-Da permeate from 45-d-old cheeselike systems was fractionated by tandem chromatographic techniques. Several peaks were obtained in each chromatogram, but only some were associated with ACE-inhibitory or antioxidant activity or both. Peptides Tyr-Gln-Glu-Pro, Val-Pro-Lys-Val-Lys, and Tyr-Gln-Glu-Pro-Val-Leu-Gly-Pro-* from beta-casein, as well as Arg-Pro-Lys and Arg-Pro-Lys-His-Pro-Ile-Lys-His-* from alpha(s1)-casein exhibited ACE-inhibitory activity. Peptides released upon cleavage of the peptide bond Leu190-Tyr191 (either in ovine or caprine beta-casein), and corresponding to the beta-casein sequence Tyr-Gln-Glu-Pro-*, possessed antioxidant activity.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2002

In vitro studies of activation of phagocytic cells by bioactive peptides.

The effect of formyl chemotactic peptide (fCTP, fMet-Leu-Phe), beta-amyloid peptides (beta-AP, 1-42, 1-16 and 25-35), and bradykinin (BK) on functional activity of phagocytic cells has been investigated. Wheat germ agglutinin (WGA) was also used as a model membrane binding agent of polypeptide nature. Murine monocyte-macrophage cell line J774.2 and normal human blood polymorphonuclear (PMN) cells were used as target phagocytic cells. Their activity was quantitatively estimated by measuring phagocytosis of killed yeast cells. Beta-AP (1-41) maximally stimulated phagocytosis at 0.1 microg/ml, BK--at 1.0 microg/ml, and fCTP--at 2.0 microg/ml. Beta-AP (1-16) and beta-AP (25-35) were inactive in used test-systems. Phagocytosis-inducing activity of beta-AP (1-42) and BK reached maximal levels in 2 h and decreased after 4-6 h of incubation. Phagocytosis numbers were compared with the indicators of phagocytic cell activation, such as absorption of neutral red dye, glucose utilization, production of super-oxide anion (NBT-test) and nitrite accumulation (indicator of NO production). NBT-test, which may be related to the killing ability of phagocytic cells towards the ingested objects, was positive only in stimulated PMN leukocytes, while the nitrite accumulation was detected only in stimulated macrophages. Nitrite accumulation in macrophages was markedly induced by lipopolysaccharide and to a lower extent by 0.5 microg/ml beta-AP (1-42). In high dose (5.0 microg/ml) beta-AP suppressed nitrite accumulation in macrophages stimulated by lipopolysaccharide. Other studied peptides were inactive in inducing nitrite accumulation. Transforming growth factor type beta suppressed phagocytic activity of PMN cells activated by beta-AP or WGA. The anti-inflammatory drugs (indomethacin and L-lysine aescinate) inhibited beta-AP (1-42)-induced phagocytosis. The interrelations between the regulatory pathways of BK, beta-AP and fCTP are discussed.

Amyloid beta-Peptides↗
PubMed2003

A new addition to the structural bioinformatics toolbox: 3D models of short bioactive peptides from multiple sequences using feedback restrained molecular dynamics (FRMD).

Modem molecular biology techniques allow the use of new approaches for the 3D mapping of 1D information. Molecular biology techniques are capable of producing large amounts of 1D information (sequences) from a number of different sources (phage displays, ESTs, etc.). In this work, we present a technique that takes advantage of large sets of 1D information and increasingly available computer power to create 3D models. For the purpose of validation the technique is first applied to the modeling of an erythropoietin analog of known 3D structure from 1D information only. The technique is then used to model the immunoreactive region of echinococcus granulosus AgB based on phage raised mimotopes for which there is no previous structural information. The technique here presented is of general application to similar problems where 1D information is available and structure activity relationships (SAR) is needed.

Animals↗
PubMed1992

Bioactive peptides and serotonin in the gut endocrine cells of the crocodile, Crocodylus niloticus (Laurenti 1768): an immunocytochemical study.

Little is known about peptide-storing endocrine cells in the gut of the Nile crocodile. As in the case of other reptiles, particularly the alligator, a limited range of peptide-storing cells was found in the gut of the crocodile. They were somatostatin, glucagon, gastrin, neurotensin and pancreatic polypeptide. The topographical distribution of cells immunoreactive to somatostatin and gastrin in the gut of the crocodile is comparable to the situation in the alligator. Glucagon and neurotensin immunoreactive cells have a much wider distribution in the gastro-intestinal tract of the crocodile compared to the alligator. Cholecystokinin and bombesin cells previously reported in the small intestine of the alligator were not detected in this study. This is the first report to demonstrate pancreatic polypeptide and serotonin immunoreactivity in the gut of a crocodilian specie.

Alligators and Crocodiles↗
PubMed1991

Structural systematics of bioactive peptides and their biosynthetic implications.

Structures of natural peptides have been linearized according to their biosynthetic constructions. The structural diversities of these peptides originate from highly complex enzyme systems, that are often found to be integrated to polyenzymes. Polyenzymes are constructed from similar elements or modules, and structural variations can be understood from mutational events and rearrangements at the DNA-level.

Enzymes↗