Boosting learning and inference in Markov logic through metaheuristics

Markov Logic (ML) combines Markov networks (MNs) and first-order logic by attaching weights to first-order formulas and using these as templates for features of MNs. State-of-the-art structure learning algorithms in ML maximize the likelihood of a database by performing a greedy search in the space of structures. This can lead to suboptimal results because of the incapability of these approaches to escape local optima. Moreover, due to the combinatorially explosive space of potential candidates these methods are computationally prohibitive. We propose a novel algorithm for structure learning in ML, based on the Iterated Local Search (ILS) metaheuristic that explores the space of structures through a biased sampling of the set of local optima. We show through real-world experiments that the algorithm improves accuracy and learning time over the state-of-the-art algorithms. On the other side MAP and conditional inference for ML are hard computational tasks. This paper presents two algorithms for these tasks based on the Iterated Robust Tabu Search (IRoTS) metaheuristic. The first algorithm performs MAP inference and we show through extensive experiments that it improves over the state-of-the-art algorithm in terms of solution quality and inference time. The second algorithm combines IRoTS steps with simulated annealing steps for conditional inference and we show through experiments that it is faster than the current state-of-the-art algorithm maintaining the same inference quality.     

The Antimicrobial Peptide Temporin G: Anti-Biofilm,Anti-Persister Activities,and Potentiator Effect of Tobramycin Efficacy Against Staphylococcus aureus

Bacterial biofilms are a serious threat for human health, and the Gram-positive bacterium Staphylococcus aureus is one of the microorganisms that can easily switch from a planktonic to a sessile lifestyle, providing protection from a large variety of adverse environmental conditions. Dormant non-dividing cells with low metabolic activity, named persisters, are tolerant to antibiotic treatment and are the principal cause of recalcitrant and resistant infections, including skin infections. Antimicrobial peptides (AMPs) hold promise as new anti-infective agents to treat such infections. Here for the first time, we investigated the activity of the frog-skin AMP temporin G (TG) against preformed S. aureus biofilm including persisters, as well as its efficacy in combination with tobramycin, in inhibiting S. aureus growth. TG was found to provoke ~50 to 100% reduction of biofilm viability in the concentration range from 12.5 to 100 µM vs ATCC and clinical isolates and to be active against persister cells (about 70–80% killing at 50–100 µM). Notably, sub-inhibitory concentrations of TG in combination with tobramycin were able to significantly reduce S. aureus growth, potentiating the antibiotic power. No critical cytotoxicity was detected when TG was tested in vitro up to 100 µM against human keratinocytes, confirming its safety profile for the development of a new potential anti-infective drug, especially for treatment of bacterial skin infections.     

Catalytically active gold sites: nanoparticles, borderline sites, clusters, cations, anions? FTIR spectra analysis of12CO and of12CO-13CO isotopic mixtures

The analysis of FTIR absorption spectra of CO and of¹²CO-¹³CO isotopic mixtures is reported for gold catalysts supported on a number of oxides. Relationships between the nanostructure and the CO adsorbing properties of the different gold catalysts are discussed. In particular, on titania supported gold, where particles of metallic nature are present, two kinds of surface sites do adsorb CO, the 6-coordinated corners and the 7- coordinated edges, while the terrace sites, 8 coordinated, are not able to adsorb even at 90 K. Moreover, the adsorbing sites are not isolated, but mutually interacting. On zirconia supported gold, the adsorbing sites, mutually interacting, are exposed at the surface of non metallic gold nanoclusters. Almost isolated and negatively charged gold adsorbing nanoclusters have been highlighted on the sample supported on reduced ceria, and, finally, isolated cationic sites on oxidized gold supported on a mixed ceria-titania oxide have been detected.     

Benzo[d]isothiazol-3-yl-benzamidines: a class of protective agents on culture of human cartilage and chondrocytes stimulated by IL-1beta

New derivatives of N-benzo[d]isothiazol-3-yl-benzamidine 6 a were synthesized as nonacidic anti-inflammatory/antidegenerative agents. We investigated the influence of the amidines 6 a-j on the production of NO, PGE(2), MMP-3, COX-2, ROS, and GAGs, key molecules involved in cartilage destruction in osteoarthritic diseases. The antidegenerative properties of the novel designed derivatives 6 b-j were improved with respect to N-benzo[d]isothiazol-3-yl-benzamidine 6 a. All of the compounds 6 a-j promoted the reduction of most of the IL-1beta-induced harmful effects. Derivatives 6 d, 6 h, and 6 j were the most potent of all the tested compounds, particularly in the human chondrocyte culture model.     

Identification and functional traits of lactic acid bacteria isolated from Ciauscolo salami produced in Central Italy

Lactic acid bacteria (LAB) from Ciauscolo salami produced in Marche Region of Central Italy, and LAB strains belonging to our laboratory collection were examined for their capability to survive at low pH and bile, to adhere to Caco-2 cells, and for antibiotic resistance. LAB from Ciauscolo were identified by ARDRA and RAPD-PCR. Our study showed that all LAB strains had good adaptation to gastric juice and moderate tolerance to bile. The adhesiveness was variable among strains but significantly lower in LAB from food. Antibiotic resistance was broadly spread among food strains, with level of resistance exceeding 15% for all the antibiotics tested. The resistance determinants erm(B) and tet(M) were found in nine strains of food origin (21.4%) while tet(L) in one strain of our collection (5%). Our work suggests that fermented foods are valuable sources of bacterial strains with functional traits of intestinal lactobacilli. These bacteria may be further studied for their use in probiotic applications.