Electrogastrography.

Electrogastrography (EGG) is the recording and the interpretation of gastric electrical activity. Recordings can be made from the gastrointestinal mucosa, serosa, or skin surface. Because of its ease of use, cutaneous EGG has gained wide acceptance. Many technical problems have been solved to obtain a good graph. The EGG is usually evaluated in terms of changes in the EGG waves amplitude and frequency. Deviations from the normal frequency of 3 cycles per minute may be referred to as brachy- or tachyarrhythmia. The clinical use of EGG has been most widely evaluated in patients with gastroparesis and functional dyspepsia. Scintigraphic gastric emptying is considered the gold standard test for evaluating gastroparesis and 13C-octanoate breath test an ideal alternative because does not use ionizing radiation. While gastric emptying evaluates the efficiency of gastric emptying, EGG focuses on the underlying myoelectrical activity. Using both EGG and 13C-octanoate breath test will be possible to detect many subset of dyspeptic patients and to understand the underlying problem.

Somatostatin receptor subtypes: basic pharmacology and tissue distribution.

The heptahelical receptor superfamily constitutes the largest single family of transmembrane-signalling molecules that regulate a wide range of physiological processes. The five somatostatin receptors represent a distinct subgroup of this seven transmembrane receptor superfamily. They range in size from 356 to 391 amino acids with 39-57% protein identity between the subtypes with 100 residues strictly conserved among the somatostatin receptor sequences. A high grade of mRNA homology exists in somatostatin receptor subtypes cloned from different species. Following somatostatin receptor binding and functional activity studies, two alternative models of ligand-binding interaction have been hypothesised. One relies on the presence of a binding pocket within the receptor structure constituted by specific amino acids residues, the other denies the presence of such binding structures and suggests that it is the interaction of agonists with specific extracellular and/or transmembrane domains that determine stable receptor structure conformation. Somatostatin receptors, as, indeed, all G-protein-coupled receptors are able to regulate their responsiveness to agonist exposure. This agonist-specific regulation includes three main events, namely, desensitisation, receptor internalisation and receptor degradation. The cell expression of somatostatin receptor subtypes, at the mRNA level, has been characterised in rodent and in human organs with multiple subtype expression in brain and peripheral tissues.

Unlabelled somatostatin analogues in treatment of digestive endocrine tumours.

Somatostatin analogues are considered first-line therapy in patients with digestive endocrine tumours. Indeed, several studies have investigated their efficacy in the control of specific symptoms and in the decrease of tumour markers. However, randomised controlled trials are needed in order to better define their role in non functioning tumours and their effect on tumour growth, which have seldom been assessed. Several new drugs have been developed over the last few years such as, for example, new long-acting formulations, universal analogues binding to all five somatostatin receptors subtypes, and cytotoxic analogues, all of which offer a promising therapeutic tool in the near future, even if further studies are needed to determine their efficacy and safety in man.

[Medical treatment of digestive neuroendocrine tumours]. / Terapia medica dei tumori neuroendocrini digestivi.

Surgery is the only therapy able to cure patients with digestive neuroendocrine tumor. However, due to the presence of diffuse metastases, radical surgery is often not feasible. In these cases, medical treatment plays a critical role, because of its ability to control symptoms in functioning tumors and to inhibit tumor growth. Different therapeutic approaches, such as chemotherapy, hepatic artery chemoembolization and targeted radio-nuclide therapy can be used alone or combined to the biologic treatment with somatostatin analogues and interferon. However, an accurate staging by imaging procedures plus a histological, immunohistochemical and biomolecular examination must be performed before planning an optimal medical treatment.

Human circular colonic smooth muscle cells possess active somatostatin receptors.

BACKGROUND & AIMS: Somatostatin alters in vivo colonic motility in different species including humans. Few data are available on a cellular basis that could explain the effects of somatostatin on human colon motility. To address these issues we studied the effects of somatostatin on isolated human circular colonic smooth muscle cells to establish whether its actions are directly or neurally mediated. METHODS: Circular smooth muscle cells were prepared by enzymatic digestion from surgical specimens of human colon (Sigma) and resuspended in HEPES buffer containing protease inhibitors. RESULTS: Cholecystokinin (1 nM), carbachol (30 nM) and KCl (20 mM) each caused a contraction of 17%, 16.5% and 15%, respectively. 1 microM of either somatostatin-14, somatostatin-28 or SMS 201-995 alone were able to produce a contraction of 5.1%, 5.7%, and 6.8%, respectively. When smooth muscle cells were preincubated with each of the above-mentioned somatostatin analogs, cholecystokinin-mediated contraction was dose-dependently inhibited only in the presence of antiproteases. The half-maximal effective concentration (EC50) for somatostatin-14, somatostatin-28 and SMS 201-995 were similar (3.5, 5.6, 3.2 nM, respectively). CONCLUSIONS: Somatostatin acts directly on human circular colonic smooth muscle cells through specific somatostatin receptors. SMS 201-995, a somatostatin receptor subtype-2 preferring analogue, shows a high affinity in inhibiting cholecystokinin-mediated contraction, suggesting the presence of somatostatin receptor subtype-2 on human circular colonic smooth muscle cells.

Staging of digestive endocrine tumours using helical computed tomography and somatostatin receptor scintigraphy.

BACKGROUND: In patients with digestive endocrine tumours, complete pre-operative staging is essential in planning proper management and evaluating treatment efficacy. To date, somatostatin receptor scintigraphy (SRS) is considered the 'gold standard' imaging procedure, and very few data are available concerning the use of helical computed tomography (hCT). This study aimed to determine the diagnostic accuracy and the ability to modify the surgical management of hCT, alone or combined with SRS. PATIENTS AND METHODS: Sixty patients were staged before surgery by hCT, SRS and tumour markers, and included in group 1 if suitable for radical surgery, otherwise in group 2. All patients underwent laparotomy followed by subsequent re-staging. RESULTS: SRS sensitivity was 77%, 48% and 67% for primary, lymph-node and liver lesions, respectively. hCT sensitivity was 94%, 69% and 94% for primary, lymph-node and liver lesions, respectively (P = 0.02 versus SRS, for liver lesions). During pre-operative evaluation, hCT correctly staged 92% and SRS 75% of patients (P = 0.02). hCT provided additional information in 17% of patients. CONCLUSIONS: Since hCT has been shown to be extremely accurate, providing essential information for the planning of surgical treatment compared with that of SRS, both techniques should be used in the pre-operative work-up of digestive endocrine tumours.