S-nitrosylation homeostasis in plants: key enzymes and regulatory pathways

The nitrosylated form of glutathione (GSNO) has been acknowledged to be the most important nitrosylating agent of the plant cell, and the tuning of its intracellular concentration is of pivotal importance for photosynthetic life. During my time as a PhD student, I focused my attention on the enzymatic systems involved in the degradation of GSNO. Hence, we decided to study the structural and catalytic features of alcohol dehydrogenases (GSNOR and ADH1) from the model land plant Arabidopsis thaliana (At). These enzymes displayed a very similar 3D structure except for their active site which might explain the extreme catalytic specialization of the two enzymes. They share NAD(H) as a cofactor, but only AtGSNOR was able to catalyze the reduction of GSNO whilst being ineffective in oxidizing ethanol. Moreover, our study on the enzyme from the unicellular green alga Chlamydomonas reinhardtii (Cr) revealed how this S-nitrosoglutathione reductase (GSNOR) specifically use NADH to catalyze GSNO reduction and how its activity responds to thiol-based post-translational modifications. Contextually, the presence of NADPH-dependent GSNO-degrading systems in algal protein extract was highlighted and resulted to be relatively efficient in this model organism. This activity could be ascribed to several proteins whose contribution has not been defined yet. Intriguingly, protein extract from GSNOR null mutants of Arabidopsis displayed an increased NADPH-dependent ability to degrade GSNO and our quantitative proteome profiling on the gsnor mutant revealed the overexpression of two class 4 aldo-keto reductases (AKR), specifically AtAKR4C8 and AtAKR4C9. Later, all four class 4 AKRs showed to possess a NADPH-dependent GSNO-degrading activity. Finally, we initiated a preliminary analysis to determine the kinetic parameters of several plant proteins, including GSNOR, AKR4Cs, and thioredoxins. These data suggested GSNOR to be the most effective enzyme in catalyzing GSNO reduction because of its extremely high catalytic proficiency compared to NADPH-dependent systems.

Comprendere la lingua dell'economia: un'analisi multidisciplinare di terminologia, comprensione e pianificazione

La tesi si concentra sull'analisi del linguaggio economico, prestando particolare attenzione alla sua terminologia. L'importanza della terminologia economica risiede nella sua capacità di facilitare una comunicazione efficace nel campo dell'economia e di permettere una comprensione più ampia dei fenomeni economici da parte del pubblico. Tuttavia, a causa della sua complessità e specificità, essa può risultare difficile da comprendere per il pubblico laico. La ricerca affronta tre questioni chiave: definire la natura della terminologia economica e l'approccio più adatto per descriverla, determinare il livello di comprensione della terminologia economica e le variabili sociali ad essa correlate, e individuare le strategie migliori per diffondere la terminologia economica nella società. Per rispondere a queste domande, l'indagine si avvale di un approccio multidisciplinare che fonde linguistica, sociolinguistica e terminologia. Il risultato è un'analisi profonda del lessico economico e delle sue collocazioni, della comprensione della terminologia da parte del pubblico e delle strategie per migliorare tale comprensione e la sua diffusione.

Seizure prediction and control in epilepsy

The first part of my thesis presents an overview of the different approaches used in the past two decades in the attempt to forecast epileptic seizure on the basis of intracranial and scalp EEG. Past research could reveal some value of linear and nonlinear algorithms to detect EEG features changing over different phases of the epileptic cycle. However, their exact value for seizure prediction, in terms of sensitivity and specificity, is still discussed and has to be evaluated. In particular, the monitored EEG features may fluctuate with the vigilance state and lead to false alarms. Recently, such a dependency on vigilance states has been reported for some seizure prediction methods, suggesting a reduced reliability. An additional factor limiting application and validation of most seizure-prediction techniques is their computational load. For the first time, the reliability of permutation entropy [PE] was verified in seizure prediction on scalp EEG data, contemporarily controlling for its dependency on different vigilance states. PE was recently introduced as an extremely fast and robust complexity measure for chaotic time series and thus suitable for online application even in portable systems. The capability of PE to distinguish between preictal and interictal state has been demonstrated using Receiver Operating Characteristics (ROC) analysis. Correlation analysis was used to assess dependency of PE on vigilance states. Scalp EEG-Data from two right temporal epileptic lobe (RTLE) patients and from one patient with right frontal lobe epilepsy were analysed. The last patient was included only in the correlation analysis, since no datasets including seizures have been available for him. The ROC analysis showed a good separability of interictal and preictal phases for both RTLE patients, suggesting that PE could be sensitive to EEG modifications, not visible on visual inspection, that might occur well in advance respect to the EEG and clinical onset of seizures. However, the simultaneous assessment of the changes in vigilance showed that: a) all seizures occurred in association with the transition of vigilance states; b) PE was sensitive in detecting different vigilance states, independently of seizure occurrences. Due to the limitations of the datasets, these results cannot rule out the capability of PE to detect preictal states. However, the good separability between pre- and interictal phases might depend exclusively on the coincidence of epileptic seizure onset with a transition from a state of low vigilance to a state of increased vigilance. The finding of a dependency of PE on vigilance state is an original finding, not reported in literature, and suggesting the possibility to classify vigilance states by means of PE in an authomatic and objectic way. The second part of my thesis provides the description of a novel behavioral task based on motor imagery skills, firstly introduced (Bruzzo et al. 2007), in order to study mental simulation of biological and non-biological movement in paranoid schizophrenics (PS). Immediately after the presentation of a real movement, participants had to imagine or re-enact the very same movement. By key release and key press respectively, participants had to indicate when they started and ended the mental simulation or the re-enactment, making it feasible to measure the duration of the simulated or re-enacted movements. The proportional error between duration of the re-enacted/simulated movement and the template movement were compared between different conditions, as well as between PS and healthy subjects. Results revealed a double dissociation between the mechanisms of mental simulation involved in biological and non-biologial movement simulation. While for PS were found large errors for simulation of biological movements, while being more acurate than healthy subjects during simulation of non-biological movements. Healthy subjects showed the opposite relationship, making errors during simulation of non-biological movements, but being most accurate during simulation of non-biological movements. However, the good timing precision during re-enactment of the movements in all conditions and in both groups of participants suggests that perception, memory and attention, as well as motor control processes were not affected. Based upon a long history of literature reporting the existence of psychotic episodes in epileptic patients, a longitudinal study, using a slightly modified behavioral paradigm, was carried out with two RTLE patients, one patient with idiopathic generalized epilepsy and one patient with extratemporal lobe epilepsy. Results provide strong evidence for a possibility to predict upcoming seizures in RTLE patients behaviorally. In the last part of the thesis it has been validated a behavioural strategy based on neurobiofeedback training, to voluntarily control seizures and to reduce there frequency. Three epileptic patients were included in this study. The biofeedback was based on monitoring of slow cortical potentials (SCPs) extracted online from scalp EEG. Patients were trained to produce positive shifts of SCPs. After a training phase patients were monitored for 6 months in order to validate the ability of the learned strategy to reduce seizure frequency. Two of the three refractory epileptic patients recruited for this study showed improvements in self-management and reduction of ictal episodes, even six months after the last training session.

Leonardo Ricci in the United States (1952-1972). A twenty-year American transfer as a turning experience in teaching and design.

The research solved the historiographic lacuna about Leonardo Ricci’s work in the United States focusing on the span 1952-1972 as a fundamental period for the architect's research, which moved from the project for the community space to macrostructures. The considered period is comprised between Ricci’s first travel to the United States and the date of his resignation from the University of Florida, one year before his resignation from the deanship of the faculty of architecture of Florence (1973). The research retraced philologically the stages of Ricci’s activity in the U.S.A. unveiling the premises and results of his American transfer, and to what extent it marked a turning period for his work as educator and designer and for the wider historiographic contest of the Sixties. The American transfer helped him grounding his belief in avoiding a priori morphological results in favor of what he called the “form-act” design method. Ricci’s research in the U.S.A. is described in his books Anonymous (XX century) and City of the Earth (unpublished). In them and in Ricci’s projects one common thread is traceable: the application of the “form-act” as the best tool to conceive urban design, a discipline established in the United States during Ricci’s first stay at M.I.T., in which he encountered the balance point between architecture and urban planning, between the architect’s sign and his being anonymous, between the collective and the individual dimension. With the notions of “anonymous architecture” and “form-act”, Urban Design and “open work” are the key words to understand Ricci’s work in the United States and in Italy. Urban design’s main goal to design the city as a collective work of art was the solution of that dychothomous research that enlivened Ricci’s work and one possible answer to that tension useful for him to seek the truth of architecture.