Characterizing the role of the PrPC N-terminal domain in protein and metal binding: NMR and XAS studies

The conversion of the cellular prion protein PrPC into the infectious isoform (PrPSc) is the key event in prion diseases. The physiological role of PrPC remains one of main challenges in prion biology, and it is an absolute requirement also for understanding prion diseases. Putative roles for PrPC are based on its localization in the central and peripheral nervous systems and on PrPC- interacting molecules or metal ions through its unstructured N-terminal domain. We analysed the function of the cellular prion protein using structural biology techniques aimed to analyze the interaction between PrPC and NCAM and PrPC with copper ions. We first focused on the structural determinants responsible for human PrPC (HuPrP) and NCAM interaction using Stimulated Emission Depletion (STED) nanoscopy, surface plasma resonance (SPR) and NMR spectroscopy approaches. Such structural and biological investigations revealed surface interacting epitopes governing the interaction between HuPrP N-terminus and the second module of NCAM Fibronectin type-3 domain, providing molecular details about the interaction between HuPrP and NCAM Fibronectin domain, and revealed a new role of PrPC N- terminus as a dynamic and functional element responsible for protein-protein interaction. Subsequently, we have investigated the role of copper in prion conversion and susceptibility with a special focus on the non-OR copper binding site. The molecular mechanisms of prion conversion are still debated. NMR-based studies on HuPrP and MoPrP globular domains have identified the \u3b22-\u3b12 loop as important element able to modulate the susceptibility of a given species to prion disease. However, recent studies have highlighted also the importance of the N- terminal region in promoting structural rearrangements to PrPSc. We studied copper coordination in the non-OR region of different species including human, sheep, bank vole and opossum. By using in vitro approaches, cell-based and computational techniques, we propose two types of copper coordination geometries, where the type-1 Cu(II) coordination displays a closed non-OR region conformation associated with less-susceptible species, while in type-2 a less structured and solvent exposed non-OR region might render the overall PrPC structure more flexible, therefore we correlate this with higher susceptibility to prion diseases. Our data highlighted how copper coordination in the non-OR copper binding site may explain the different susceptibility to prion diseases observed in these mammalian species. Ultimately, in the present thesis we expanded our knowledge on how the N-terminus of PrPC regulates the physiological functions of PrPC and how it is involved in the prion conversion

Structural Consequences of Copper Binding to the Prion Protein

Prion, or PrPSc, is the pathological isoform of the cellular prion protein (PrPC) and it is the etiological agent of transmissible spongiform encephalopathies (TSE) affecting humans and animal species. The most relevant function of PrPC is its ability to bind copper ions through its flexible N-terminal moiety. This review includes an overview of the structure and function of PrPC with a focus on its ability to bind copper ions. The state-of-the-art of the role of copper in both PrPC physiology and in prion pathogenesis is also discussed. Finally, we describe the structural consequences of copper binding to the PrPC structure

Improved time-resolved measurements of inorganic ions in particulate matter by PILS-IC integrated with a sample pre-concentration system

A particle-into-liquid sampler coupled with ion chromatograph (PILS-IC) for the on-line measurement of inorganic ions has been modified by the insertion of two ion-exchange pre-concentration cartridges that enrich the sample during the period of the IC analysis. The limits of detection of the modified instrument were 10-15 times lower and the time coverage 24 times higher (from 2 to 48 min per hour) than those of the original PILS-IC setup. The instrumental performance in terms of recovery and break-through volume from the cartridges was satisfactory. The modified PILS-IC was operated in comparison with a diffusion denuder line and with a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) during a short intensive measurement period organized in the framework of the European Monitoring and Evaluation Programme (EMEP), a co-operative program for monitoring and evaluation of the long-range transmission of the air pollutants in Europe. The instrument showed a quantitative response in agreement with the results of the diffusion lines, and an ability to trace fine concentration variations not so different from the performance of the much more complex HR-TOF-AMS. From the time patterns of the ion concentrations measured by the modified PILS-IC, it was possible to obtain useful information about the variations in the air quality and in the strength of the particulate matter sourc

A mechanistic review of Parkin activation

Parkin and phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1) constitute a feed-forward signalling pathway that mediates autophagic removal of damaged mitochondria (mitophagy). With over 130 mutations identified to date in over 1000 patients with early onset parkinsonism, Parkin is considered a hot spot of signalling pathways involved in PD aetiology. Parkin is an E3 ligase and how its activity is regulated has been extensively studied: inter-domain interactions exert a tight inhibition on Parkin activity; binding to phospho-ubiquitin relieves this auto-inhibition; and phosphorylation of Parkin shifts the equilibrium towards maximal Parkin activation. This review focusses on recent, structural findings on the regulation of Parkin activity. What follows is a mechanistic introduction to the family of E3 ligases that includes Parkin, followed by a brief description of structural elements unique to Parkin that lock the enzyme in an autoinhibited state, contrasted with emerging models that have shed light on possible mechanisms of Parkin activation

Modelling of Fireballs Generated After the Catastrophic Rupture of Hydrogen Tanks

The interest towards hydrogen skyrocketed in the last years. Thanks to its potential as an energy carrier, hydrogen will be soon handled in public and densely populated areas. Therefore, accurate models are necessary to predict the consequences of unwanted scenarios. These new models should be employed in the consequence analysis, a phase of risk assessment, and thus aid the selection, implementation, and optimization of effective risk-reducing measures. This will increase safety of hydrogen technologies and therefore favour their deployment on a larger scale. Hydrogen is known to be an extremely flammable gas with a low radiation flame compared to hydrocarbons. However, luminous fireballs were generated after the rupture of both compressed gaseous and liquid hydrogen tanks in many experiments. Moreover, it was demonstrated that conventional empirical correlations, initially developed for hydrocarbon fuels, underestimate both dimension and duration of hydrogen fireballs recorded during small-scale tests (Ustolin and Paltrinieri, 2020). The aim of this study is to obtain an analysis of hydrogen fireballs to provide new critical insights for consequence analysis. A comparison among different correlations is conducted when predicting fireball characteristics during the simulation of past experiments where both gaseous and liquid hydrogen tanks were intentionally destroyed. All the models employed in this study are compared with the experimental results for validation purposes. Specific models designed for hydrogen can support the design of hydrogen systems and increasing their safety and promote their future distribution

Fragments Generated During Liquid Hydrogen Tank Explosions

Liquid hydrogen (LH2) may be employed to transport large quantities of pure hydrogen or be stored onboard of ships, airplanes and trains fuelled by hydrogen, thanks to its high density compared to gaseous compressed hydrogen. LH2 is a cryogenic fluid with an extremely low boiling point (-253°C at atmospheric pressure) that must be stored in double-walled vacuum insulated tanks to limit the boil-off formation. There is limited knowledge on the consequences of LH2 tanks catastrophic rupture. In fact, the yield of the consequences of an LH2 tank explosion (pressure wave, fragments and fireball) depend on many parameters such as tank dimension, filling degree, and tank internal conditions (temperature and pressure) prior the rupture. Only two accidents provoked by the rupture of an LH2 tank occurred in the past and a couple of experimental campaigns focussed on this type of accident scenario were carried out for LH2. The aim of this study is to analyse one of the LH2 tank explosion consequences namely the fragments. The longest horizontal and vertical ranges of the fragments thrown away from the blast wave are estimated together with the spatial distribution around the tank. Theoretical models are adopted in this work and validated with the experimental results. The proposed models can aid the risk analysis of LH2 storage technologies and provide critical insights to plan a prevention and mitigation strategy and improve the safety of hydrogen applications

Detection of prion seeding activity in the olfactory mucosa of patients with Fatal Familial Insomnia

Fatal Familial Insomnia (FFI) is a genetic prion disease caused by a point mutation in the prion protein gene (PRNP) characterized by prominent thalamic atrophy, diffuse astrogliosis and moderate deposition of PrP Sc in the brain. Here, for the first time, we demonstrate that the olfactory mucosa (OM) of patients with FFI contains trace amount of PrP Sc detectable by PMCA and RT-QuIC. Quantitative PMCA analysis estimated a PrP Sc concentration of about 1 \uc3\u97 10-14g/ml. In contrast, PrP Sc was not detected in OM samples from healthy controls and patients affected by other neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease and frontotemporal dementia. These results indicate that the detection limit of these assays is in the order of a single PrP Sc oligomer/molecule with a specificity of 100%

Orthodontics Surgical Assistance (Piezosurgery®): Experimental Evidence According to Clinical Results

Orthodontic tooth movement (OTM) is based on intermitted or continuous forces applied to teeth, changing the mechanical loading of the system and arousing a cellular response that leads to bone adaptation. The traditional orthodontic movement causes a remodeling of the alveolar bone and changes in the periodontal structures that lead to tooth movement. The use of a piezoelectric instrument in orthodontic surgery has already shown great advantages. The purpose of this study is to rank the behavior of inflammatory mediators in accelerating orthodontic tooth movement. Ten patients with malocclusion underwent orthodontic surgical treatment, which included a first stage of surgically guided orthodontic movement (monocortical tooth dislocation and ligament distraction, MTDLD) to accelerate orthodontic movements. In all cases, corticotomy was performed by Piezosurgery. Bone and dental biopsy was executed to evaluate changes in the cytokines IL-1beta, TNF-alpha and IL-2 in different time intervals (1, 2, 7, 14 and 28 days). The molecular mediators are IL-1 beta, TNF-alpha and IL-2. Immediately after the surgical procedure there was a mild expression of the three molecular markers, while the assertion of IL-1 beta and TNF-alpha reached the maximum value after 24 h and 48 h, indicating a strong activation of the treated tissues. The Piezosurgery® surgical technique induces an evident stress in short times, within 24–48 h from the treatment, but it decreases significantly during the follow-up. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Have There Been any Changes in the Epidemiology and Etiology of Maxillofacial Trauma During the COVID-19 Pandemic? An Italian Multicenter Study

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a significant impact on people's behavior. The aim of this study has been to evaluate how the SARS-CoV-2 pandemic has impacted the incidence and the features of maxillofacial fractures presented at 6 Italian tertiary centers. Clinical records of all the patients diagnosed for facial fractures between February 23 and May 23, 2019 and 2020 were retrospectively reviewed. Any differences in patient number and characteristics and fracture etiology and site between the 2 groups were then statistically analyzed.There has been a 69.1% decrease in the number of incoming patients during the pandemic. The number of foreign patients has decreased significantly (23.3% versus 9.6%, P\u200a=\u200a0.011) while the average age has increased (38.6 versus 45.6 years old, P\u200a=\u200a0.01). Specific statistical significant differences for accidental falls (31.8% versus 50.1%, P\u200a=\u200a0.005) and sports injuries (16.9% versus 1.4%, P\u200a<\u200a0.001) were found. Concerning fracture sites, significant differences have been found in relation to nasal (22.5% versus 11.4%, P\u200a=\u200a0.009) and frontal sinus (0.9% versus 4.4%, P\u200a=\u200a0.037) fractures. In conclusion, SARS-CoV-2 pandemic has significantly changed the epidemiology and the etiology of facial traumas