Role of phosphodiesterase 5 in synaptic plasticity and memory

Phosphodiesterases (PDEs) are enzymes that break down the phosphodiesteric bond of the cyclic nucleotides, cAMP and cGMP, second messengers that regulate many biological processes. PDEs participate in the regulation of signal transduction by means of a fine regulation of cyclic nucleotides so that the response to cell stimuli is both specific and activates the correct third messengers. Several PDE inhibitors have been developed and used as therapeutic agents because they increase cyclic nucleotide levels by blocking the PDE function. In particular, sildenafil, an inhibitor of PDE5, has been mainly used in the treatment of erectile dysfunction but is now also utilized against pulmonary hypertension. This review examines the physiological role of PDE5 in synaptic plasticity and memory and the use of PDE5 inhibitors as possible therapeutic agents against disorders of the central nervous system (CNS)

Metrics, Explainability and the European AI Act Proposal

On 21 April 2021, the European Commission proposed the first legal framework on Artificial Intelligence (AI) to address the risks posed by this emerging method of computation. The Commission proposed a Regulation known as the AI Act. The proposed AI Act considers not only machine learning, but expert systems and statistical models long in place. Under the proposed AI Act, new obligations are set to ensure transparency, lawfulness, and fairness. Their goal is to establish mechanisms to ensure quality at launch and throughout the whole life cycle of AI-based systems, thus ensuring legal certainty that encourages innovation and investments on AI systems while preserving fundamental rights and values. A standardisation process is ongoing: several entities (e.g., ISO) and scholars are discussing how to design systems that are compliant with the forthcoming Act, and explainability metrics play a significant role. Specifically, the AI Act sets some new minimum requirements of explicability (transparency and explainability) for a list of AI systems labelled as “high-risk” listed in Annex III. These requirements include a plethora of technical explanations capable of covering the right amount of information, in a meaningful way. This paper aims to investigate how such technical explanations can be deemed to meet the minimum requirements set by the law and expected by society. To answer this question, with this paper we propose an analysis of the AI Act, aiming to understand (1) what specific explicability obligations are set and who shall comply with them and (2) whether any metric for measuring the degree of compliance of such explanatory documentation could be designed. Moreover, by envisaging the legal (or ethical) requirements that such a metric should possess, we discuss how to implement them in a practical way. More precisely, drawing inspiration from recent advancements in the theory of explanations, our analysis proposes that metrics to measure the kind of explainability endorsed by the proposed AI Act shall be risk-focused, model-agnostic, goal-aware, intelligible, and accessible. Therefore, we discuss the extent to which these requirements are met by the metrics currently under discussion

AI: profili etici. Una prospettiva etica sull'Intelligenza Artificiale: princ\uecpi, diritti e raccomandazioni

As technologies become more and more pervasive in our everyday life new questions arise, for example, about security, accountability, fairness and ethics. These concerns are about all the realities that are involved or committed in designing, implementing, deploying and using the technology. This document addresses such concerns by presenting a set of practical obligations and recommendations for the development of applications and systems based on Artificial Intelligence (AI) techniques. These are derived from a definition of rights resulting from principles and ethical values rooted in the foundational charters of our social organization

Ecologically Different Fungi Affect Arabidopsis Development: Contribution of Soluble and Volatile Compounds

<div><p>Plant growth and development can be influenced by mutualistic and non-mutualistic microorganisms. We investigated the ability of the ericoid endomycorrhizal fungus <i>Oidiodendron maius</i> to influence growth and development of the non-host plant <i>Arabidopsis thaliana</i>. Different experimental setups (non-compartmented and compartmented co-culture plates) were used to investigate the influence of both soluble and volatile fungal molecules on the plant phenotype. <i>O</i>. <i>maius</i> promoted growth of <i>A</i>. <i>thaliana</i> in all experimental setups. In addition, a peculiar clumped root phenotype, characterized by shortening of the primary root and by an increase of lateral root length and number, was observed in <i>A</i>. <i>thaliana</i> only in the non-compartmented plates, suggesting that soluble diffusible molecules are responsible for this root morphology. Fungal auxin does not seem to be involved in plant growth promotion and in the clumped root phenotype because co-cultivation with <i>O</i>. <i>maius</i> did not change auxin accumulation in plant tissues, as assessed in plants carrying the DR5::GUS reporter construct. In addition, no correlation between the amount of fungal auxin produced and the plant root phenotype was observed in an <i>O</i>. <i>maius</i> mutant unable to induce the clumped root phenotype in <i>A</i>. <i>thaliana</i>. Addition of active charcoal, a VOC absorbant, in the compartmented plates did not modify plant growth promotion, suggesting that VOCs are not involved in this phenomenon. The low VOCs emission measured for <i>O</i>. <i>maius</i> further corroborated this hypothesis. By contrast, the addition of CO₂ traps in the compartmented plates drastically reduced plant growth, suggesting involvement of fungal CO₂ in plant growth promotion. Other mycorrhizal fungi, as well as a saprotrophic and a pathogenic fungus, were also tested with the same experimental setups. In the non-compartmented plates, most fungi promoted <i>A</i>. <i>thaliana</i> growth and some could induce the clumped root phenotype. In the compartmented plate experiments, a general induction of plant growth was observed for most other fungi, especially those producing higher biomass, further strengthening the role of a nonspecific mechanism, such as CO₂ emission.</p></div

El libro virtual: un recurso que llegó para quedarse

Introducción. Como partícipes del proceso enseñanza y aprendizaje, consideramos esencial estimular el interés y motivación de los y las estudiantes con el fin de lograr la integración entre los tres elementos que intervienen en la construcción del conocimiento: docente-alumno-objeto de estudio. Por ello, resulta de vital importancia la selección y elaboración de materiales didácticos virtuales para la mediación del aprendizaje significativo. Objetivo. Diseñar material virtual con intencionalidad didáctica, para sostener, apoyar, guiar el proceso de aprendizaje.Facultad de Odontologí