Palaeoproteomics guidelines to identify proteinaceous binders in artworks following the study of a 15th-century painting by Sandro Botticelli's workshop.

Undertaking the conservation of artworks informed by the results of molecular analyses has gained growing importance over the last decades, and today it can take advantage of state-of-the-art analytical techniques, such as mass spectrometry-based proteomics. Protein-based binders are among the most common organic materials used in artworks, having been used in their production for centuries. However, the applications of proteomics to these materials are still limited. In this work, a palaeoproteomic workflow was successfully tested on paint reconstructions, and subsequently applied to micro-samples from a 15th-century panel painting, attributed to the workshop of Sandro Botticelli. This method allowed the confident identification of the protein-based binders and their biological origin, as well as the discrimination of the binder used in the ground and paint layers of the painting. These results show that the approach is accurate, highly sensitive, and broadly applicable in the cultural heritage field, due to the limited amount of starting material required. Accordingly, a set of guidelines are suggested, covering the main steps of the data analysis and interpretation of protein sequencing results, optimised for artworks.

Proton pump inhibitor use and association with spontaneous bacterial peritonitis in patients with cirrhosis and ascites.

OBJECTIVE: To evaluate the literature regarding the efficacy and safety of proton pump inhibitors (PPIs) when they are used in patients with cirrhosis and ascites. DATA SOURCES: A literature search was conducted using MEDLINE (1966-May 2012) and Web of Science (1990-May 2012) with the terms proton pump inhibitor, antisecretory therapy, cirrhosis, ascites, spontaneous bacterial peritonitis, and Clostridium difficile. The search was restricted to articles published in English on the use of PPIs in humans. Reference citations from identified published articles were reviewed for relevant information. STUDY SELECTION AND DATA EXTRACTION: All articles in English identified from the data sources were evaluated for inclusion. One case series, 8 retrospective case-control trials, and 1 meta-analysis were identified. DATA SYNTHESIS: Cirrhosis may cause complications such as portal hypertension, esophageal varices, and ascites. Patients may be prescribed PPIs without clear indications or because of their propensity to develop upper gastrointestinal symptoms and bleeding. However, gastric acidity is a major nonspecific defense mechanism and there is insufficient evidence on the need for chronic acid suppression in patients with cirrhosis. It is postulated that the portal hypertensive environment in cirrhosis and the acid suppression from PPIs can increase the risk of spontaneous bacterial peritonitis and C. difficile infection in patients with cirrhosis with ascites. Several retrospective studies and 1 meta-analysis have confirmed this association. CONCLUSIONS: Patients with cirrhosis and ascites should be monitored carefully while on PPIs for a possible increased risk of infection from spontaneous bacterial peritonitis and C. difficile. Prospective randomized trials are needed to confirm this association. Clinicians should be aware of this lesser known adverse effect of PPIs.

Area-dependent migration by ringlet butterflies generates a mixture of patchy population and metapopulation attributes.

Interpretation of spatially structured population systems is critically dependent on levels of migration between habitat patches. If there is considerable movement, with each individual visiting several patches, there is one "patchy population"; if there is intermediate movement, with most individuals staying within their natal patch, there is a metapopulation; and if (virtually) no movement occurs, then the populations are separate (Harrison 1991, 1994). These population types actually represent points along a continuum of much to no mobility in relation to patch structure. Therefore, interpretation of the effects of spatial structure on the dynamics of a population system must be accompanied by information on mobility. We use empirical data on movements by ringlet butterflies, Aphantopus hyperantus, to investigate two key issues that need to be resolved in spatially-structured population systems. First, do local habitat patches contain largely independent local populations (the unit of a metapopulation), or merely aggregations of adult butterflies (as in patchy populations)? Second, what are the effects of patch area on migration in and out of the patches, since patch area varies considerably within most real population systems, and because human landscape modification usually results in changes in habitat patch sizes? Mark-release-recapture (MRR) data from two spatially structured study systems showed that 63% and 79% of recaptures remained in the same patch, and thus it seems reasonable to call both systems metapopulations, with some capacity for separate local dynamics to take place in different local patches. Per capita immigration and emigration rates declined with increasing patch area, while the resident fraction increased. Actual numbers of emigrants either stayed the same or increased with area. The effect of patch area on movement of individuals in the system are exactly what we would have expected if A. hyperantus were responding to habitat geometry. Large patches acted as local populations (metapopulation units) and small patches simply as locations with aggregations (units of patchy populations), all within 0.5 km2. Perhaps not unusually, our study system appears to contain a mixture of metapopulation and patchy-population attributes.