Le perforazioni radicolari iatrogene: classificazione e possibilità di trattamento ortogrado

RiassuntoObiettivoScopo dell'articolo è descrivere le principali classificazioni delle perforazioni iatrogene e valutare le più attuali tecniche di trattamento per via ortograda.Materiali e metodiLe perforazioni di tipo iatrogeno della radice sono per definizione tragitti artificiali che mettono in comunicazione l'endodonto con le strutture parodontali di sostegno del dente. La causa di tali comunicazioni è legata ad errori commessi dall'operatore durante le diverse fasi del trattamento endodontico. Le perforazioni possono essere classificate in relazione alla loro posizione e alla loro dimensione.RisultatiGrazie al supporto di sistemi ingrandenti quali il microscopio operatorio e l'impiego di materiali per la riparazione come il mineral trioxide aggregate, oggi è possibile migliorare la prognosi di questi trattamenti.ConclusioniLa posizione della perforazione in relazione all'attacco epiteliale e alla cresta ossea è importante per stabilire una corretta prognosi. L'applicazione di protocolli operativi rigorosi con l'impiego del mineral trioxide aggregate consentono di migliorare la prognosi di elementi con perforazione radicolare.SummaryObjectiveAim of this paper is to describe iatrogenic perforations of the root canal system, to classify them and to evaluate the methods and techniques available to treat them.Materials and methodsIatrogenic perforations of the root canal system are defined as artificial communications between the endodontic environment and the periodontal tissue surrounding the dental root. Often, some procedural errors related to the operative techniques employed during the endodontic treatment may lead to misshaping or, in the worst cases, perforation. These communications might be divided into several classes and are classified according to the site, dimension and location of the perforation.ResultsDue to technical supports like magnification loups or operative microscope the dentist might have the advantage to locate and seal the perforation with some new biocompatibile materials such as mineral trioxide aggregate, making this separative procedure more predictable than in the past.ConclusionsThe perforation position related to epithelial junction and bony crest is strategic from a clinical point of view in order to establish a correct prognosis. A clear operative protocol and the use of proper sealing materials could both lead to a better prognosis for all treatable root canal perforations

DOF-binding sites additively contribute to guard cell-specificity of AtMYB60 promoter

<p>Abstract</p> <p>Background</p> <p>We previously demonstrated that the <it>Arabidopsis thaliana </it>AtMYB60 protein is an R2R3MYB transcription factor required for stomatal opening. <it>AtMYB60 </it>is specifically expressed in guard cells and down-regulated at the transcriptional levels by the phytohormone ABA.</p> <p>Results</p> <p>To investigate the molecular mechanisms governing <it>AtMYB60 </it>expression, its promoter was dissected through deletion and mutagenesis analyses. By studying different versions of <it>AtMYB60 </it>promoter::GUS reporter fusions in transgenic plants we were able to demonstrate a modular organization for the <it>AtMYB60 </it>promoter. Particularly we defined: a minimal promoter sufficient to confer guard cell-specific activity to the reporter gene; the distinct roles of different DOF-binding sites organised in a cluster in the minimal promoter in determining guard cell-specific expression; the promoter regions responsible for the enhancement of activity in guard cells; a promoter region responsible for the negative transcriptional regulation by ABA. Moreover from the analysis of single and multiple mutants we could rule out the involvement of a group of DOF proteins, known as CDFs, already characterised for their involvement in flowering time, in the regulation of <it>AtMYB60 </it>expression.</p> <p>Conclusions</p> <p>These findings shed light on the regulation of gene expression in guard cells and provide new promoter modules as useful tools for manipulating gene expression in guard cells, both for physiological studies and future biotechnological applications.</p

The rice StMADS11-like genes OsMADS22 and OsMADS47 cause floral reversions in Arabidopsis without complementing the svp and agl24 mutants

During floral induction and flower development plants undergo delicate phase changes which are under tight molecular control. MADS-box transcription factors have been shown to play pivotal roles during these transition phases. SHORT VEGETATIVE PHASE (SVP) and AGAMOUS LIKE 24 (AGL24) are important regulators both during the transition to flowering and during flower development. During vegetative growth they exert opposite roles on floral transition, acting as repressor and promoter of flowering, respectively. Later during flower development they act redundantly as negative regulators of AG expression. In rice, the orthologues of SVP and AGL24 are OsMADS22, OsMADS47, and OsMADS55 and these three genes are involved in the negative regulation of brassinosteroid responses. In order to understand whether these rice genes have maintained the ability to function as regulators of flowering time in Arabidopsis, complementation tests were performed by expressing OsMADS22 and OsMADS47 in the svp and agl24 mutants. The results show that the rice genes are not able to complement the flowering-time phenotype of the Arabidopsis mutants, indicating that they are biologically inactive in Arabidopsis. Nevertheless, they cause floral reversions, which mimic the SVP and AGL24 floral overexpressor phenotypes. Yeast two-hybrid analysis suggests that these floral phenotypes are probably the consequence of protein interactions between OsMADS22 and OsMADS47 and other MADS-box proteins which interfere with the formation of complexes required for normal flower development

Phosphorylation of CONSTANS and its COP1-dependent degradation during photoperiodic flowering of Arabidopsis

Seasonal flowering involves responses to changes in day length. In Arabidopsis thaliana, the CONSTANS (CO) transcription factor promotes flowering in the long days of spring and summer. Late flowering in short days is due to instability of CO, which is efficiently ubiquitinated in the dark by the CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) E3 ligase complex. Here we show that CO is also phosphorylated. Phosphorylated and unphosphorylated forms are detected throughout the diurnal cycle but their ratio varies, with the relative abundance of the phosphorylated form being higher in the light and lower in the dark. These changes in relative abundance require COP1, because in the cop1 mutant the phosphorylated form is always more abundant. Inactivation of the PHYTOCHROME A (PHYA), CRYPTOCHROME 1 (CRY1) and CRYPTOCHROME 2 (CRY2) photoreceptors in the phyA cry1 cry2 triple mutant most strongly reduces the amount of the phosphorylated form so that unphosphorylated CO is more abundant. This effect is caused by increased COP1 activity, as it is overcome by introduction of the cop1 mutation in the cop1 phyA cry1 cry2 quadruple mutant. Degradation of CO is also triggered in red light, and as in darkness this increases the relative abundance of unphosphorylated CO. Finally, a fusion protein containing truncated CO protein including only the carboxy-terminal region was phosphorylated in transgenic plants, locating at least one site of phosphorylation in this region. We propose that CO phosphorylation contributes to the photoperiodic flowering response by enhancing the rate of CO turnover via activity of the COP1 ubiquitin ligase.Peer reviewe