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Abstract Background One of the most interesting problems in molecular immunology is epitope mapping, i.e. the identification of the regions of interaction between an antigen and an antibody. The solution to this problem, even if approximate, would help in designing experiments to precisely map the residues involved in the interaction and could be instrumental both in designing peptides able to mimic the interacting surface of the antigen and in understanding where immunologically important regions are located in its three-dimensional structure. From an experimental point of view, both genetically encoded and chemically synthesised peptide libraries can be used to identify sequences recognized by a given antibody. The problem then arises of which region of a folded protein the selected peptides correspond to. Results We have developed a method able to find the surface region of a protein that can be effectively mimicked by a peptide, given the structure of the protein and the maximum number of side chains deemed to be required for recognition. The method is implemented as a publicly available server. It can also find and report all peptide sequences of a specified length that can mimic the surface of a given protein and store them in a database. The immediate application of the server is the mapping of antibody epitopes, however the system is sufficiently flexible for allowing other questions to be asked, for example one can compare the peptides representing the surface of two proteins known to interact with the same macromolecule to find which is the most likely interacting region. Conclusion We believe that the MEPS server, available at http://www.caspur.it/meps, will be a useful tool for immunologists and structural and computational biologists. We plan to use it ourselves to implement a database of "surface mimicking peptides" for all proteins of known structure and proteins that can be reliably modelled by comparative modelling.

Object: The question of whether preoperative therapy with somatostatin analogs can improve surgical outcome in acromegaly has not been definitively answered. In this paper, the authors report the effects of preoperative treatment with somatostatin analogs in a large sample of patients with acromegaly., Methods: Between 1990 and 2003, 399 consecutive patients with acromegaly underwent surgery at the Istituto Scientifico San Raffaele. Thirty-three patients who had previously undergone surgery or radiation treatment, 48 patients treated with somatostatin analogs for fewer than 3 months, and patients who had stopped therapy for too long a time before surgery were excluded from the study. One hundred forty-three patients who had received somatostatin analogs prior to surgery (Group 1) were randomly matched to 143 patients who had never been treated with somatostatin analogs (Group 2). Matching criteria were tumor size and invasiveness into the cavernous sinus. Before surgery, Group 1 patients showed reduction of growth hormone levels to less than 50% of baseline in 64% of cases, but insulin-like growth factor-I was normalized in only 19.5%. Surgical remission occurred in 81 Group 1 patients (56.6%) and in 91 Group 2 patients (63.6%; p = 0.28). No significant difference in the remission rate was observed when cases were analyzed according to tumor size or invasiveness. Logistic regression analysis confirmed that pretreatment with somatostatin analogs was not associated with surgical outcome. Surgical morbidity was mild and similar in Group 1 and Group 2 patients (7 and 5.6%, respectively; p = 0.81). Surgical remission and complication rates in patients with acromegaly who received treatment with somatostatin analogs prior to surgery were not significantly different from those of matched patients who did not receive these agents., Conclusions: At present, the routine use of presurgical therapy with somatostatin analogs for patients with acromegaly cannot be recommended.