Biomedical subjects

P Robberecht

Publications and source records attributed to P Robberecht.

291 records · Page 17Linked to original sources

PubMedDate not supplied

Growth factors in colorectal tumorigenesis.

Colorectal tumorigenesis involves complex events including multiple genetic alterations in a well-known multistep mechanism called the adenoma-carcinoma sequence. Furthermore, growth and differentiation of normal and transformed cells are influenced by several growth factors, cytokines and hormones. Most of them, like Transforming Growth Factor alpha, Epidermal Growth Factor, Fibroplast Growth Factors, Insulin-like Growth Factors, and gastrin for instance have mitogenic effects. Transforming Growth Factor beta has however a key role in modulating these factors and has preferentially inhibitory growth effect. It is thought to play a strategic role in colorectal tumorigenesis although its mechanisms of action are complex and only partly understood. The aim of the present study is to review the effects of several growth factors, focusing on the role of TGF-beta in colorectal tumorigenesis.

Cell Transformation, Neoplastic↗

PubMedDate not supplied

Current status on chromogranin A and pancreastatin.

The authors review the biochemical and biological properties of chromogranins and pancreastatin. Chromogranins A, B and C are acidic proteins of a molecular mass of 48,000, 76,000 and 67,000, respectively, located in the secretory granules of the neuroendocrine cells. Since large amounts of chromogranin A were found in most neuroendocrine tumours, chromogranin A plasma determination is a diagnostic tool even in silent tumours. Pancreastatin is a peptide derived from chromogranin A, which inhibits insulin secretion, exocrine pancreatic secretion and gastric acid secretion, and which stimulates glucagon secretion. Pancreastatin has different molecular forms, the major form being a high molecular form of 92 amino acids, found by the authors in human stomach- and colon extracts and in a liver metastasis of a gastrinoma. The controlled proteolysis of chromogranin A in gut neuroendocrine cells generates predominantly the high molecular weight form.

Chromogranin A↗

PubMedDate not supplied

[Recombinant receptors for testing agonists and antagonists of VIP and PACAP receptors].

VIP and PACAP are structurally related neuropeptides. They interact with multiple classes of receptors that have been cloned recently. These receptors may be divided into two main classes: the PACAP type I receptors with a high affinity for PACAP and a low affinity for VIP and the PACAP type II receptors (with a high affinity for PACAP and VIP). Five different forms of the PACAP type I receptors are described and result from an alternative splicing of the messenger. Two distinct forms (VIP1 and VIP2 receptors) of the PACAP type II receptors are described. Considering this high number of variants and the coexistence of several variants in the same cell, the development of cell lines expressing a single type of receptor was required for the testing of selective agonists and antagonists. However, limits in the interpretation of the results obtained in the cell lines expressing the recombinant receptors were obvious: discovery of unusual receptor states and unusual coupling of cellular effectors when a high number of receptors was expressed.

Amino Acid Sequence↗