University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

Molecular systematics of Hydrobiidae (Mollusca: Gastropoda: Rissooidea): testing monophyly and phylogenetic relationships

Abstract: The rissooidean family Hydrobiidae Troschel, 1857 is supposedly one of the largest gastropod families with more than 400 recent genera assigned. Due to the limited number of robust anatomical characters in hydrobiids, the high degree of intraspecific variation, the unknown phylogenetic significance of anatomical characters, and the high degree of homoplasy in anatomical characters, its systematic is confusing and phylogenetic relationships within the family and with other rissooidean groups are poorly understood. We studied fragments of the COI and 18S genes from representatives of 40 genera to determine if the family Hydrobiidae (as defined by Kabat and Hershler, 1993) is monophyletic, if the family Hydrobiidae could be resolved using these genes, and whether the Cochliopidae are a distinct family as previously suggested. The cluster patterns in the combined 18S + COI tree as well as in the individual 18S and COI trees show that the Hydrobiidae of Kabat and Hershler (1993) are polyphyletic. The ...

Post placement affects survival of endodontically treated premolars.

Abstract: Clinical evidence is lacking regarding the influence of the amount of residual coronal dentin and of post placement on the failure risk of endodontically compromised teeth. The aim of this prospective clinical trial was to assess whether these factors significantly affect the two-year survival of restored pulpless premolars. A sample of 210 individuals provided six experimental groups of 40 premolars in need of endodontic treatment. Groups were defined based on the amount of dentin left at the coronal level. Within each group, in half of the teeth selected at random, a fiber post was inserted inside the root canal, whereas in the remaining half of the premolars, no post was placed. All teeth were covered with a crown. The Cox regression analysis revealed that post placement resulted in a significant reduction of failure risk (p < 0.001). Failure risk was increased for teeth under the "no ferrule" (p = 0.001) and "ferrule effect" conditions (p = 0.004).

Magic gamma-ray telescope observation of the perseus cluster of galaxies : implications for cosmic rays, dark matter, and ngc 1275

Abstract: The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. The resulting upper limits on the gamma-ray emission above 100 GeV are in the range of 4.6-7.5 x 10(-12) cm(-2) s(-1) for spectral indices from -1.5 to -2.5, thereby constraining the emission produced by cosmic rays, dark matter annihilations, and the central radio galaxy NGC 1275. Results are compatible with cosmological cluster simulations for the cosmic-ray-induced gamma-ray emission, constraining the average cosmic ray-to-thermal pressure to < 4% for the cluster core region (< 8% for the entire cluster).

A Functional Genomics Approach to Establish the Complement of Carbohydrate Transporters in Streptococcus pneumoniae

Abstract: The aerotolerant anaerobe Streptococcus pneumoniae is part of the normal nasopharyngeal microbiota of humans and one of the most important invasive pathogens. A genomic survey allowed establishing the occurrence of twenty-one phosphotransferase systems, seven carbohydrate uptake ABC transporters, one sodium∶solute symporter and a permease, underlining an exceptionally high capacity for uptake of carbohydrate substrates. Despite high genomic variability, combined phenotypic and genomic analysis of twenty sequenced strains did assign the substrate specificity only to two uptake systems. Systematic analysis of mutants for most carbohydrate transporters enabled us to assign a phenotype and substrate specificity to twenty-three transport systems. For five putative transporters for galactose, pentoses, ribonucleosides and sulphated glycans activity was inferred, but not experimentally confirmed and only one transport system remains with an unknown substrate and lack of any functional annotation. Using a metabolic approach, 80% of the thirty-two fermentable carbon substrates were assigned to the corresponding transporter. The complexity and robustness of sugar uptake is underlined by the finding that many transporters have multiple substrates, and many sugars are transported by more than one system. The present work permits to draw a functional map of the complete arsenal of carbohydrate utilisation proteins of pneumococci, allows re-annotation of genomic data and might serve as a reference for related species. These data provide tools for specific investigation of the roles of the different carbon substrates on pneumococcal physiology in the host during carriage and invasive infection.