S. Katsoulis

Gastric emptying time of fluids and solids in healthy subjects determined by 13C breath tests: influence of age, sex and body mass index.

Background and Aim:  Disturbance of gastric emptying leads to a variety of symptoms. Furthermore, gastric motility disorders might play a role in the pathophysiology of functional dyspepsia. In previous studies 13C breath tests were validated as non‐invasive tools in the measurement of gastric emptying time. So far, reliable reference values of healthy subjects are missing and the impact of constitutional traits (age, sex, body mass index [BMI]) needs to be clarified.

Human galanin modulates human colonic motility in vitro. Characterization of structural requirements.

BACKGROUND Human galanin (hGal) is a 30-residue non-amidated gut-brain peptide that shows considerable sequence divergence compared with galanin (Gal) forms of other species. Conflicting results have been reported with regard to the structural requirements for its modulatory action on gut motility. METHODS We investigated the effect of human and rat Gal and substituted analogues of Gal on the contractility of longitudinal muscle strips of the human colon in vitro. RESULTS Both hGal and rGal contracted the preparations in a concentration-dependent and tetrodotoxin-resistant manner without difference in sensitivity. The NH2-terminally truncated peptides hGal (3-30) and rGal (3-29) were inactive, whereas the NH2-terminal fragments, hGal (1-21) and rGal (1-18), remained fully responsive. Single amino acid substitutions at NH2-terminal positions showed divergent results: substitution of Trp2 reduced significantly potency and efficacy, whereas substitutions at positions 1, 3, 4, or 5 did not markedly modify the bioactivity of Gal. Galantide, a high-affinity Gal antagonist in the central nervous system, is a full agonist in human colonic smooth muscle. CONCLUSION The COOH-terminal part of Gal contributes mainly the receptor-binding affinity of the peptide, whereas the NH2-terminal region is essential for biologic activity.

Specific monoclonal antibodies neutralize the action of PACAP 1–27 or PACAP 1–38 on intestinal muscle strips in vitro

The gut-brain neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) is a novel highly conserved member of the secretin-glucagon-VIP peptide family comprising 38 or 27 amino acid residues. In this study, we investigate the actions of PACAP 1-27 or PACAP 1-38 on jejunal and caecal muscle strips from pig or guinea pig and demonstrate the neutralizing effect of two PACAP-specific monoclonal antibodies of the IgG1 subtype, RSP27II and RSP38. These antibodies were used to set up assay systems specific for PACAP 1-27 or PACAP 1-38. Monoclonal antibody RSP27II recognizes exclusively PACAP 1-27, whereas RSP38 binds only PACAP 1-38. PACAP 1-27 and PACAP 1-38 relax taenia caeci dose-dependently in the presence of guanethidine and scopolamine. Both peptides inhibit the spontaneous contractions of porcine jejunal muscle strips equipotently. Monoclonal antibodies RSP27II and RSP38 specifically neutralize the actions of either exogenously applied or endogenously released PACAP. Thus, they represent processing-specific tools to examine the physiological role of both molecular forms of PACAP in the gastrointestinal tract.