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Proper matrix application is crucial in obtaining high quality matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI). Solvent-free sublimation was essentially introduced as an approach of homogeneous coating that gives small crystal size of the organic matrix. However, sublimation has lower extraction efficiency of analytes. Here, we present that a simple sonication step after the hydration in standard sublimation protocol significantly enhances the sensitivity of MALDI MSI. This modified procedure uses a common laboratory ultrasonicator to immobilize the analytes from tissue sections without noticeable delocalization. Improved imaging quality with additional peaks above 10 kDa in the spectra was thus obtained upon sonication treatment.ᅟ [ABSTRACT FROM AUTHOR]

A criticalanalysis of virtual screening results published between2007 and 2011 was performed. The activity of reported hit compoundsfrom over 400 studies was compared to their hit identification criteria.Hit rates and ligand efficiencies were calculated to assist in theseanalyses, and the results were compared with factors such as the sizeof the virtual library and the number of compounds tested. A seriesof promiscuity, druglike, and ADMET filters were applied to the reportedhits to assess the quality of compounds reported, and a careful analysisof a subset of the studies that presented hit optimization was performed.These data allowed us to make several practical recommendations withrespect to selection of compounds for experimental testing, definitionof hit identification criteria, and general virtual screening hitcriteria to allow for realistic hit optimization. A key recommendationis the use of size-targeted ligand efficiency values as hit identificationcriteria. [ABSTRACT FROM AUTHOR]