Ultrafast spectro-microscopy of highly excited low dimensional materials

Born-Oppenheimer approximation (ABO) is the assumption that the motion of atomic nuclei and electrons in molecules can be separated and independently treated. In solids, ABO is well justified when the energy gap between ground and excited electronic states is larger than the energy scale of the nuclear motion. Graphene represents a notable exception of this acceptantance. In particular, here we unravel the key role of the gapless linear Dirac dispersion in the vibrational Raman response of the system in the case of impulsively photoexcited graphene. First, we unambiguously describe Four-Wave Mixing (FWM) processes in graphene, which depend on the resonant nature of the electronic interactions. Indeed, the overall spectral response is described in terms of a third order diagrammatic description of the light-matter interaction. We disclose that the interference between Coherent anti-Stokes Raman Scattering (CARS) and Non-Vibrationally Resonant Background (NVRB) generates Lorentzian dip spectral profiles. Actually, by introducing an experimental time delayed FWM scheme, able to modify the relative strength of the two contributions, we observe the first evidence of CARS peak equivalent to the Raman spectrum in graphene. Second, we adopt sub picosecond photoexcitation which impulsively localize energy into graphene electronic subsystem. While the response of hot charge carriers is well-characterized, unraveling the behavior of optical phonons under strongly out-of- equilibrium conditions remains a challenge. Using a 3-ps laser excitation, which trades off between impulsive stimulation and spectral resolution, we show how the Raman response of graphene can be detected in presence of an electronic subsystem temperature largely exceeding that of the phonon bath. We find a peculiar behaviour of the period and lifetime of both the G and 2D phonons as function of the carriers temperature in the range 1700-3100 K, suggesting a broadening of the Dirac cones. Accordingly, we reconsider the traditional scenario of the electron-phonon scattering in a highly excited transient regim

Neoadjuvant endocrine therapy for luminal breast tumors: State of the art, challenges and future perspectives

Neoadjuvant endocrine treatment (NET) associates to satisfactory rates of breast conservative surgery and conversions from inoperable to operable hormone receptor-positive (HR+)/HER2-negative breast cancer (BC), with less toxicities than neoadjuvant chemotherapy (NACT) and similar outcomes. Hence, it has been proposed as a logical alternative to NACT in patients with HR+/HER2- BC candidate to a neoadjuvant approach. Nevertheless, potential barriers to the widespread use of NET include the heterogeneous nature of patient response coupled with the long duration needed to achieve a clinical response. However, interest in NET has significantly increased in the last decade, owing to more in-depth investigation of several biomarkers for a more adequate patient selection and on-treatment benefit monitoring, such as PEPI score, Ki67 and genomic assays. This review is intended to describe the state-of-the-art regarding NET, its future perspectives and potential integration with molecular biomarkers for the optimal selection of patients, regimen and duration of (neo)adjuvant treatments

Microbiological and host factors are involved in promoting the periodontal failure of metaloceramic crowns

This study was aimed at looking into the microbiological/inflammatory parameters predicting the periodontal success/failure of fixed prostheses. Microbiological and inflammatory patterns were studied at 102 sites having metaloceramic crowns in place from 3 to 6 years and divided in healthy sites (HS), gingivitis affected (MG), and periodontitis affected (PB). Total bacterial flora and selected indicator species in subgingival plaque were quantified by quantitative real-time PCR. The concentrations of IL-1β, IL-6, and TNF-α were determined in gingival crevicular fluid (GCF) by enzyme-linked immunosorbent assays. The experimental sites showed no significant difference with respect to the age and gender of the patients and to the position of the crown margins. Poor marginal adaptation was significantly higher in MG and PB. The total amounts of bacteria per probing depth showed no significant differences among the three groups and their controls, while both MG and PB sites showed altered patterns in the distribution of specific bacteria. Both MG and PB sites showed significantly higher levels of inflammatory cytokines in GCF. The control teeth of PB subjects showed significantly higher levels of IL-1β as compared to other control sites. Data confirm that the application of metaloceramic crowns is a factor of risk for the development of gingival/periodontal inflammation. This risk is possibly associated with microbiological and host factors that predispose to the onset of periodontal alterations at sites reconstructed with metaloceramic crowns. These factors, once their role is confirmed by longitudinal studies, could be used to set up rapid tests to early predict the onset of periodontal disease at reconstructed sites. © 2011 Springer-Verlag

Isolation of Staphylococcus aureus and progression of periodontal lesions in aggressive periodontitis

This work evaluates whether isolation and toxicity of subgingival Staphylococcus aureus strains correlate with progression of periodontal lesions and whether isolates are characterized by a specific genomic background. The study involved 165 subjects affected by generalized aggressive periodontitis. Three sets of samples of supragingival and subgingival plaque were obtained at 45-day intervals from active and non-active sites, to detect S. aureus. Susceptibility to antibiotics, the presence of 17 genes, genomic restriction profiles and multilocus sequence typing (MLST) were performed to characterize all isolates. S. aureus was detected in 37.6% of the subjects. Subgingival colonization rates were 66.1% and 12.9% for active and non-active sites, respectively (P<0.01). Supragingival and subgingival isolates were shown to be distinct by molecular genotyping and DNA fingerprint analysis. MLST showed that isolates were not genetically related and no sequence type was predominant in any of the two locations. These data demonstrate that S. aureus is associated with the progression of aggressive periodontitis and that a specific set of characters is necessary for the bacterium to colonize subgingival sites. Comparative analysis of genomic structure and genetic-related data suggest that the periodontal environment could promote genetic evolution of strains. Copyright © by BIOLIFE, s.a.s

Moving beyond PARP Inhibition: Current State and Future Perspectives in Breast Cancer

Breast cancer is the most frequent and lethal tumor in women and finding the best therapeutic strategy for each patient is an important challenge. PARP inhibitors (PARPis) are the first, clinically approved drugs designed to exploit synthetic lethality in tumors harboring BRCA1/2 mutations. Recent evidence indicates that PARPis have the potential to be used both in monotherapy and combination strategies in breast cancer treatment. In this review, we show the mechanism of action of PARPis and discuss the latest clinical applications in different breast cancer treatment settings, including the use as neoadjuvant and adjuvant approaches. Furthermore, as a class, PARPis show many similarities but also certain critical differences which can have essential clinical implications. Finally, we report the current knowledge about the resistance mechanisms to PARPis. A systematic PubMed search, using the entry terms “PARP inhibitors” and “breast cancer”, was performed to identify all published clinical trials (Phase I-II-III) and ongoing trials (ClinicalTrials.gov), that have been reported and discussed in this review

Preparation and characterization of antimicrobial wound dressings based on silver, gellan, PVA and borax

Silver-loaded dressings are designed to provide the same antimicrobial activity of topical silver, with the advantages of a sustained silver release and a reduced number of dressing changes. Moreover, such type of dressing must provide a moist environment, avoiding fiber shedding, dehydration and adherence to the wound site. Here we describe the preparation of a novel silver-loaded dressing based on a Gellan/Hyaff (R) (Ge-H) non woven, treated with a polyvinyl alcohol (PVA)/borax system capable to enhance the entrapment of silver in the dressing and to modulate its release. The new hydrophilic non woven dressings show enhanced water uptake capability and slow dehydration rates. A sustained silver release is also achieved. The antibacterial activity was confirmed on Staphylococcus aureus and Pseudomonas aeruginosa. (C) 2012 Elsevier Ltd. All rights reserved

Chasing bacteria within the cells using levofloxacin-loaded hyaluronic acid nanohydrogels

In the present work, an innovative approach based on the delivery of levofloxacin (LVF) from polysaccharide nanohydrogels for the treatment of bacterial intracellular infections is described. The nanohydrogels (NHs) were obtained by self-assembling of the hyaluronic acid-cholesterol amphiphilic chains in aqueous environment. LVF, a fluoroquinolone antibiotic scarcely efficient in intracellular infections, was entrapped within such NHs by nanoprecipitation, thus forming a drug delivery system (LVF-NHs) that was tested for its activity on different bacteria strains. The MIC values of levofloxacin-loaded nanohydrogels were determined for Staphylococcus aureus and Pseudomonas aeruginosa strains and compared to those obtained using free LVF. The intracellular antimicrobial activity of LVF-NHs and free LVF was compared on HeLa epithelial cell line infected by the above mentioned bacteria, and the increase in antibacterial efficacy of LVF-NHs with respect to that of free LVF was evidenced. The obtained results allow to conclude that this new approach can be considered as really promising method for intracellular infection treatments. © 2014 Elsevier B.V. All rights reserved

Diffusion of meticillin-resistant Staphylococcus aureus USA300 strains in central Italy

Meticillin-resistant Staphylococcus aureus (MRSA) is an outstanding, clonally evolving pathogen that in recent years, under the selective pressure of antibiotics, has acquired the crucial ability to infect people outside of hospitals. MRSA USA300 has progressively become synonymous with severe community-associated staphylococcal disease worldwide. Whilst spreading worldwide, these clones have progressively acquired resistance to several antibiotics and have gained the ability to cause infections in hospital settings. Recently, USA300-related strains showing resistance to several antibiotics have been isolated from community-acquired infections in Italy. This paper reports the high frequency of isolation of USA300-related strains both from community- and hospital-acquired infections in central Italy as well as their genotypic characteristics and antibiotic susceptibility. Analysis of these characteristics by partial least squares discriminant analysis enabled it to be demonstrated that whilst moving from the community to the hospital setting these isolates underwent an adaptive process that generated clones showing distinctive characteristics. These observations further support the hypothesis that the threatening generation of strains combining both resistance and virulence is becoming a reality, and stress the necessity of constant molecular epidemiological surveillance of MRSA. (c) 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved