709 research outputs found
New peptide nucleic acids for biotechnological applications
No full textIn the present study was designed and realized a new similar to the PNA. It is a chiral nucleo-γ-peptide, dabPNA, isomer of the aegPNA unit and characterized by a 2,4-diaminobutyric acid (DABA)-based backbone carrying the carboxymethylated nucleobase on its α amino group.
Differently from aegPNA monomers, dabPNA presents a shorter backbone (3C between the nitrogen atom and the carbonyl) and an enhanced distance between the nucleobase and the backbone, i.e. 3 atoms (1N+2C) instead of 2C in aegPNAs. Furthermore, in comparison with ornPNA that binds to RNA forming a stable triplex, daba-based PNA has a methylene group less in the backbone.
To achieve dabPNA oligomers, the new monomers tL-dab, tD-dab, aL-dab and aD-dab were synthesized in good yield using suitable protected building blocks and characterized by NMR and ESI-MS techniques.
Initially, the homothymine oligomers (tL-dab)12 and (tD-dab)6 were synthesized, using a synthetic strategy that ensured the maintenance of chirality during the coupling steps, and tested for hybridization towards natural nucleic acids. No binding evidence with both DNA (dA12) and RNA (A12) was revealed by CD and UV experiments. Furthermore, the insertion of a single tL-dab unit in the middle or at N-terminus of a homothymine aegPNA chain leads to a decreased binding efficiency to the target DNA in comparison to full aegPNA.Since dabPNAs based on L- and D-DABA don’t bind natural nucleic acids, we explored the possibility that complementary nucleopeptides based on D or L-DABA could bind between themselves. This property would be interesting in order to develop novel DABA-based dendrimeric systems, as new materials, and also to realize new diagnostic tools, as for example new molecular beacon probe. To verify this interesting possibility, the monomers aL-dab and aD-dab were oligomerized to the homoadenine hexamers (aL-dab)6 and (aD,L-dab)6. In order to find the correct combination of chirality suitable for obtaining the binding, also the (tD,L-dab)6 oligomer were realized to perform the hybridization studies. From CD and UV experiments, binding evidence was revealed in the case of the complementary oligomers with alternate chirality, (aD,L-dab)6 and (tD,L-dab)6, even if the stability of the complex formed was not so high (Tm 11°C).
Furthermore, some interesting properties relative to the self-complementary oligomer (aL−dab-tD−dab)3 emerged from preliminary DLS experiments that evidenced the formation of multimeric aggregates for this system.
These results, together with the high serum stability of the DABA-based oligomers, suggest further studies on dabPNAs as new self-recognizing bio-inspired polymers, with the potentiality to develop new nanomaterials or new biotechnological tools in bioengineering and biomedical applications
"Alla Sicilia tendeva il cuor di Dante". Dante e Federico II, tra lingua, poesia e politica
No full textThe figure of democracy and its legitimacy
No full textThis is the author accepted manuscript. The final version is available from Palgrave Macmillan via the DOI in this record.Critical Exchange, pp 205–242. Authors: Carlo Invernizzi Accetti, Alessandro Mulieri, Hubertus Buchstein, Dario Castiglione, Lisa Disch, Jason Frank, Yves Sintomer, Nadia Urbinat
A Lateglacial and early Holocene pollen record from Valle di Castiglione (Rome): Vegetation dynamics and climate implications
No full textA new pollen record from Valle di Castiglione near Rome (core VdC09) has been studied with the aim of providing a detailed reconstruction of the vegetation history of the Roman landscape between 13,800 and 7700 cal BP, in response to the Lateglacial and early Holocene climate events. An open landscape dominated by steppe vegetation characterized the Lateglacial, so that only a modest increase of trees took place during the Allerod interstadial. The Intra Allerod Cold Period induced instability in the development of the woody communities. The Holocene forest recovery started around 11,600 cal BP, but definite forest development occurred only around 11,100 cal BP, at the end of the Preboreal Oscillation, which produced an important re-expansion of herbs. The evergreen Mediterranean vegetation was constantly present in the landscape, even during the Lateglacial cold fluctuations. A clear early Holocene increase in evergreen trees corresponds to the attainment of high and stable values in the GISP2 delta O-18 curve, around 10,200 cal BP
Erratum to: Oculo-auriculo-vertebral spectrum: going beyond the first and second pharyngeal arch involvement (Neuroradiology, (2017), 59, 3, (305-316), 10.1007/s00234-017-1795-1)
No full textIn the article “Oculo-auriculo-vertebral spectrum: going beyond the first and second pharyngeal arch involvement”, the list of author names was incorrect. Author names were inverted with the surname preceding first name. Davide Brotto 1, Renzo Manara 2, Sara Ghiselli 1, Elisa Lovo 1, Rodica Mardari 3, Irene Toldo 4 , Alessandro Castiglione 1, Giovanni Schifano 1, Valentina Stritoni 1, Roberto Bovo 1, Patrizia Trevisi 1, Alessandro Martini 1
Timely HAART initiation may pave the way for a better viral control
No full textAbstract Background When to initiate antiretroviral therapy in HIV infected patients is a diffcult clinical decision. Actually, it is still a matter of discussion whether early highly active antiretroviral therapy (HAART) during primary HIV infection may influence the dynamics of the viral rebound, in case of therapy interruption, and overall the main disease course. Methods In this article we use a computational model and clinical data to identify the role of HAART timing on the residual capability to control HIV rebound after treatment suspension. Analyses of clinical data from three groups of patients initiating HAART respectively before seroconversion (very early), during the acute phase (early) and in the chronic phase (late), evidence differences arising from the very early events of the viral infection. Results The computational model allows a fine grain assessment of the impact of HAART timing on the disease outcome, from acute to chronic HIV-1 infection. Both patients' data and computer simulations reveal that HAART timing may indeed affect the HIV control capability after treatment discontinuation. In particular, we find a median time to viral rebound that is significantly longer in very early than in late patients. Conclusions A timing threshold is identified, corresponding to approximately three weeks post-infection, after which the capability to control HIV replication is lost. Conversely, HAART initiation occurring within three weeks from the infection could allow to preserve a significant control capability. This time could be related to the global triggering of uncontrolled immune activation, affecting residual immune competence preservation and HIV reservoir establishment.</p
The many shapes of diversity: ecological and evolutionary determinants of biodiversity through time
No full textLeonardo Sciascia e Federico Campbell: un dialogo intercontinentale
No full textLeonardo Sciascia ha influito profondamente sull’opera narrativa e saggistica di Federico Campbell, uno dei suoi maggiori studiosi nel mondo ispanofono (e non solo). In questa sede si vuole proporre un’introduzione alla figura di Campbell, al rapporto fra i due autori – che si conobbero anche di persona – e alla sua produzione, in prevalenza ai testi più incentrati su temi “sciasciani” e alla monografia La memoria di Sciascia
Total oxidation of trichloroethylene over mayenite (Ca12Al14O33) catalyst
No full textThe catalytic oxidation of gaseous trichloroethylene (TCE), mediated by a cost effective mayenite support, was studied in a fixed bed reactor. Mayenite was synthetized by using hydrothermal method and characterized before and after catalytic oxidation experiments by using XRD, N 2 -sorption (BET), SEM-EDX, TEM and FTIR; the reaction products were analyzed by means of GC–MS, IC and a IR-based CO 2 probe. The results showed that mayenite promoted the total oxidation of TCE in the temperature range 300–500 °C, where TCE was quantitatively converted in CO 2 and chlorine. The mayenite catalyst showed high recyclability and could be used for several reaction cycles without any loss of activity and selectivity. Owing to its characteristics, mayenite was found to be a promising catalyst for the TCE total conversion and remediation
- …
