Commercially available preparations of natural porcine glucose-dependent insulinotropic polypeptide (GIP) were subjected to reverse phase HPLC. The material was found to give rise to 4 peaks which were characterized by HPLC-retention time and N-terminal sequence analysis. They represented: intact porcine GIP(1-42), 58% (wt/wt); the GIP-fragment des-tyr-ala-GIP(3-42), 32% (wt/wt); cholecystokinin (CCK)-33 2% (wt/wt); CCK-39 2% (wt/wt). HPLC-pure GIP(1-42) stimulated insulin release in rat isolated pre-cultured pancreatic islets in the presence of 16.7 mM glucose up to 240% vs. control, whereas the fragment des-tyr-ala-GIP(3-42) did neither increase insulin release nor exhibit antagonistic activity to GIP(1-42) at 100 ng/ml. These results indicate that commercially available porcine GIP-preparations may contain the biologically inactive des-tyr-ala-GIP(3-42) in high amounts, and in addition may be contaminated by CCK-peptides. HPLC-characterization of these peptide preparations prior to any biological study is crucial.

Pericardiocentesis is the treatment of choice for primary symptomatic pericardial effusion. In recurrent pericardial effusion surgical approaches appear to be preferable.

The analogues tested are biologically active and resistant to degradation by dipeptidyl peptidase IV. Their greater metabolic stability may help to realize the potential of GLP-1 analogues in diabetes therapy.

No abstract

No abstract