173,735 research outputs found
Le pale di San Paolo in Campo Marzio e di San Giorgio in Braida. Nuovi studi e ricerche
No full textEsito della diagnostica non invasiva su dipinti di Paolo Veronese studiati in occasione delle mostre a Londra e Veron
A new and efficient route to the synthesis of pyrazole and pyrimidine C-nucleoside derivatives
No full textA new route to the synthesis of pyrazole and pyrimidine C-nucleosides, involving as the key step a metal catalysed reaction of beta-D-ribofuranosyl ketoesters with alkyl cyanoformates, is described. 2,3,5-Tri-O-benzoyl-beta-D-ribofuranosyl cyanide (1) reacts with alpha-bromoesters, in the presence of zinc dust, to give beta-D-ribofuranosyl-enaminoesters 2 which are easily hydrolised to beta-ketoesters 3. The reactions of compounds 3 with alkyl cyanoformates, in the presence of catalytic amounts of [Cu(acac)(2)], afford C-glycosyl enaminoketosters 4. These compounds react with benzylhydrazine and acetamidine to give pyrazole and pyrimidine C-nucleosides 5 and 6 respectively. (C) 1998 Elsevier Science Ltd. All rights reserved
Povegliano Veronese (Verona): estesa necropoli in campo aperto
No full textSintesi del rilevante contesto funerario di Povegliano Veronese, con planimetria
Chapter The struggle for (self-)integration. Manuscripts, liturgy and networks in Verona at the time of Bishop Ratold (c. 802-840/3)
No full textBetween the 780s and the 840s the episcopal see of Verona was held by bishops coming from beyond the Alps, appointed by the Carolingian rulers and charged with control over a prestigious and strategically key bishopric. They were called upon to boost the communications between the local elites and the political and social machinery of the Carolingian world. In order to achieve that, they first had to negotiate their own integration in their new field of action, and to be acknowledged as effective political mediators between Verona and the rulers. The tools they used to do that were, on the one hand, their own skills and previous experience, on the other, the centre for textual production, preservation and dissemination they found in Verona, that is, the cathedral scriptorium and library. The books that can be attributed to them allow us to keep trace of the networks of relationships and cultural exchanges they developed, linking the two sides of the Alps. This paper focuses more specifically on the activities and endeavours of Bishop Ratold (c. 802-840). The liturgical and hagiographical manuscripts produced in Verona in that period are examined as key markers of Ratold’s intellectual networks, and of the ways in which he used them for his own need for self-integration. They also provide elements casting light on the introduction and reception of the Carolingian cultural reforms in the Kingdom of Italy
Synthesis of pyrazole C-nucleosides via Tin(IV) chloride-promoted reactions of beta-D-ribofuranosyl cyanide with beta-dicarbonyl compounds
No full text2,3,5-Tri-O-benzoyl-beta-D-ribofuranosyl cyanide reacts with methyl acetoacetate and diethyl malonate in the presence of stoichiometric amounts of SnCl4 to give a beta-D-ribofuranosyl-enaminoketoester and a beta-D-ribofuranosyl-enaminodiester, respectively. The beta-D-ribofuranosyl-enaminoketoester was debenzoylated, treated with 2,2-dimethoxypropane and tert-butyl-dimethylsilyl chloride to give the methyl 3-amino-3-(5'-O-tert-butyldimethylsilyl-2',3'-O-isopropylidene-beta-D-ribofuranosyl)-2-acetyl propanoate obtained in good yield together with small amounts of its alpha-anomer. The reactions of the beta-anomer with hydrazine, methyl- and phenylhydrazine carried out under controlled experimental conditions, afforded the pyrazole C-nucleosides in good yields as beta-anomers. (C) 2002 Elsevier Science Ltd. All rights reserved
Role and regulation of miR-483 in cancer
No full textThe hsa-mir-483 locus is located at chromosome 11p15.5 within intron 2 of the IGF2 locus. Because of its location, de-regulated in Wilms’ tumor and other neoplasia, I hypothesized that this microRNA had a potential role in tumors. By analyzing 19 Wilms’ tumors, I proved that miR-483-3p is indeed over-expressed in 100% of the cases and a co-regulation with the over-expression of IGF2 was found.
However, several other types of common adult cancers exhibit high or even extremely high levels of miR-483-3p expression without IGF2 over-expression. Indeed, independently from IGF2, the expression of the miR-483-3p could also be induced by the oncoprotein β-catenin through a novel interaction with the basic Helix-Loop-Helix protein upstream stimulatory transcription factor 1 (USF1).
I also show that β-catenin itself is a target of miR-483-3p, triggering a negative regulative loop that becomes ineffective in cells harbouring activating mutations of β-catenin pathway.
The potential oncogenic role of miR-483-3p was supported by the findings that its ectopic expression protects cells from apoptosis and, conversely, its inhibition increase the level of apoptosis. To understand the mechanisms of its action, I investigated potential gene targets. Among these, an important pro-apoptotic protein, Puma, were inhibited by miR-483-3p. My results indicate that miR-483-3p functions as an anti-apoptotic oncogene, coordinately over-expressed with IGF2 in Wilms’ tumors or induced by β-catenin activation in other tumor types
Scintillators and semiconductor detectors
No full textVarious processes occur during the detection of ionizing radiation within a scintillator, and proper detection designs are needed [1, 2, 3]. As a consequence of the interaction of radiation with the scintillation material, ionisation and excitation processes arise, and the energy (or part of it) of the incoming radiation is transferred to the atoms and molecules of the scintillator. Following deexcitation processes, photons originate in the ultraviolet/visible (UV/VIS) region of the electromagnetic spectrum, light that must be collected and converted in a suitable electric signal. In many cases, light collection simply may be obtained by coupling the scintillator directly with an optical detector, typically a photomultiplier tube (PMT). In other cases, depending on the particular application or measurement geometry, a light guide is required, which efficiently transmits the light emitted by the scintillator to the optical device. Finally, light photons are converted into electrons, and the resulting basic electric signal is amplified and properly processed. Let us consider in more detail the scintillation conversion mechanism in a wide band-gap material. This process may be explained by considering the energy band structure of an activated crystalline scintillator. An inorganic scintillator is indeed usually a crystalline solid containing a small amount of dopant, acting as a luminescent centre, which creates energy levels within the forbidden band between the valence band and the conduction band. Moreover, the natural impurities and defects present in the crystal are the origination of other energy levels, which may act as traps during the charge transport
A new route to the synthesis of pyrazole and pyrimidine C-nucleoside derivatives
No full textA new route to the synthesis of pyrazole and pyrimidine C-nucleosides, which involves as the key step a metal promoted reaction of beta-D-ribofuranosyl ketoesters with alkyl cyanoformates is described. 2,3,5-Tri-O-benzoyl-beta-D-ribofuranosyl cyanide 1 reacts with alpha-bromoesters, in the presence of zinc dust, to give beta-D-ribofuranosyl-enaminoesters 2 which are hydrolysed with IN hydrochloric acid to beta-ketoesters 3. The reactions of beta-ketoesters 3 with alkyl cyanoformates, in the presence of tin(IV) chloride or of catalytic amounts of metal acetylacetonates, afford beta-D-ribofuranosyl enaminoketoesters 4. These compounds react with benzylhydrazine and acetamidine to give pyrazole and pyrimidine C-nucleosides (6,7). (C) 1999 Elsevier Science Ltd. All rights reserved
Choroidal abnormalities in central serous chorioretinopathy
No full textPurpose: To evaluate choroidal abnormalities in acute (A–ChCSC) and chronic (C–ChCSC) central serous chorioretinopathy evaluated with dynamic indocyanine green angiography (d–ICGA).
Methods: We examined 40 consecutive patients with A–ChCSC or C–ChCSC. Dynamic fluorescein angiography (d–FA) and indocyanine green angiography (d–ICGA) were performed by means of a confocal scanning laser ophthalmoscope (Heidelberg HRA – Heidelberg Engineering Germany) using 1 ml of mixed solution obtained with 200 mg of fluorescein and 10 mg of indocyanine green, followed by 5 cc of saline flush. d–FA was used to confirm the diagnosis and d–ICGA to analyze the choroidal flow and characteristics. Two independent observers evaluated the early and late phase of the angiographies. Results: d–ICGA shows different characteristics in A–ChCSC and in C–ChCSC. In A–ChCSC the most evident abnormality is the choroidal filling delay (8 out 15 – 53%) present not only in the area of the fluorescein leakage. In A–ChCSC transient multifocal dilatations of choroidal veins are evident (80%), not always related to the site of serous detachment. In C–ChCSC a diffuse and stable dilations of the veins are visible during the venous phase and usually correspond to the area of the retinal pigment epithelium decompensation (22 out 25 – 88%). In the late phase intrachoroidal leakage is present in A–ChCSC and C–ChCSC. Conclusions:The different choroidal abnormalities visualized in A–ChCSC and C–ChCSC seem to suggest a different mechanism in these two diseases. The presence of choroidal dilation in C–ChCSC could explain the effect of photodynamic therapy as suggest by different authors
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