Glial activation in prion diseases is selectively triggered by neuronal PrPSc

Although prion infections cause cognitive impairment and neuronal death, transcriptional and translational profiling shows progressive derangement within glia but surprisingly little changes within neurons. Here we expressed PrP(C) selectively in neurons and astrocytes of mice. After prion infection, both astrocyte and neuron-restricted PrP(C) expression led to copious brain accumulation of PrPSc. As expected, neuron-restricted expression was associated with typical prion disease. However, mice with astrocyte-restricted PrP(C) expression experienced a normal life span, did not develop clinical disease, and did not show astro- or microgliosis. Besides confirming that PrPSc is innocuous to PrP(C)-deficient neurons, these results show that astrocyte-born PrPSc does not activate the extreme neuroinflammation that accompanies the onset of prion disease and precedes any molecular changes of neurons. This points to a nonautonomous mechanism by which prion-infected neurons instruct astrocytes and microglia to acquire a specific cellular state that, in turn, drives neural dysfunction

A conformational switch controlling the toxicity of the prion protein

Prion infections cause conformational changes of the cellular prion protein (PrPC) and lead to progressive neurological impairment. Here we show that toxic, prion-mimetic ligands induce an intramolecular R208-H140 hydrogen bond (‘H-latch’), altering the flexibility of the α2–α3 and β2–α2 loops of PrPC. Expression of a PrP2Cys mutant mimicking the H-latch was constitutively toxic, whereas a PrPR207A mutant unable to form the H-latch conferred resistance to prion infection. High-affinity ligands that prevented H-latch induction repressed prion-related neurodegeneration in organotypic cerebellar cultures. We then selected phage-displayed ligands binding wild-type PrPC, but not PrP2Cys. These binders depopulated H-latched conformers and conferred protection against prion toxicity. Finally, brain-specific expression of an antibody rationally designed to prevent H-latch formation prolonged the life of prion-infected mice despite unhampered prion propagation, confirming that the H-latch is an important reporter of prion neurotoxicity

PHACTR1 genetic variability is not critical in small vessel ischemic disease patients and PcomA recruitment in C57BL/6J mice

Recently, several genome-wide association studies identified PHACTR1 as key locus for five diverse vascular disorders: coronary artery disease, migraine, fibromuscular dysplasia, cervical artery dissection and hypertension. Although these represent significant risk factors or comorbidities for ischemic stroke, PHACTR1 role in brain small vessel ischemic disease and ischemic stroke most important survival mechanism, such as the recruitment of brain collateral arteries like posterior communicating arteries (PcomAs), remains unknown. Therefore, we applied exome and genome sequencing in a multi-ethnic cohort of 180 early-onset independent familial and apparently sporadic brain small vessel ischemic disease and CADASIL-like Caucasian patients from US, Portugal, Finland, Serbia and Turkey and in 2 C57BL/6J stroke mouse models (bilateral common carotid artery stenosis [BCCAS] and middle cerebral artery occlusion [MCAO]), characterized by different degrees of PcomAs patency. We report 3 very rare coding variants in the small vessel ischemic disease-CADASIL-like cohort (p.Glu198Gln, p.Arg204Gly, p.Val251Leu) and a stop-gain mutation (p.Gln273*) in one MCAO mouse. These coding variants do not cluster in PHACTR1 known pathogenic domains and are not likely to play a critical role in small vessel ischemic disease or brain collateral circulation. We also exclude the possibility that copy number variants (CNVs) or a variant enrichment in Phactr1 may be associated with PcomA recruitment in BCCAS mice or linked to diverse vascular traits (cerebral blood flow pre-surgery, PcomA size, leptomeningeal microcollateral length and junction density during brain hypoperfusion) in C57BL/6J mice, respectively. Genetic variability in PHACTR1 is not likely to be a common susceptibility factor influencing small vessel ischemic disease in patients and PcomA recruitment in C57BL/6J mice. Nonetheless, rare variants in PHACTR1 RPEL domains may influence the stroke outcome and are worth investigating in a larger cohort of small vessel ischemic disease patients, different ischemic stroke subtypes and with functional studies

PHACTR1 genetic variability is not critical in small vessel ischemic disease patients and PcomA recruitment in C57BL/6J mice

Recently, several genome-wide association studies identified PHACTR1 as key locus for five diverse vascular disorders: coronary artery disease, migraine, fibromuscular dysplasia, cervical artery dissection and hypertension. Although these represent significant risk factors or comorbidities for ischemic stroke, PHACTR1 role in brain small vessel ischemic disease and ischemic stroke most important survival mechanism, such as the recruitment of brain collateral arteries like posterior communicating arteries (PcomAs), remains unknown. Therefore, we applied exome and genome sequencing in a multi-ethnic cohort of 180 early-onset independent familial and apparently sporadic brain small vessel ischemic disease and CADASIL-like Caucasian patients from US, Portugal, Finland, Serbia and Turkey and in 2 C57BL/6J stroke mouse models (bilateral common carotid artery stenosis [BCCAS] and middle cerebral artery occlusion [MCAO]), characterized by different degrees of PcomAs patency. We report 3 very rare coding variants in the small vessel ischemic disease-CADASIL-like cohort (p.Glu198Gln, p.Arg204Gly, p.Val251Leu) and a stop-gain mutation (p.Gln273*) in one MCAO mouse. These coding variants do not cluster in PHACTR1 known pathogenic domains and are not likely to play a critical role in small vessel ischemic disease or brain collateral circulation. We also exclude the possibility that copy number variants (CNVs) or a variant enrichment in Phactr1 may be associated with PcomA recruitment in BCCAS mice or linked to diverse vascular traits (cerebral blood flow pre-surgery, PcomA size, leptomeningeal microcollateral length and junction density during brain hypoperfusion) in C57BL/6J mice, respectively. Genetic variability in PHACTR1 is not likely to be a common susceptibility factor influencing small vessel ischemic disease in patients and PcomA recruitment in C57BL/6J mice. Nonetheless, rare variants in PHACTR1 RPEL domains may influence the stroke outcome and are worth investigating in a larger cohort of small vessel ischemic disease patients, different ischemic stroke subtypes and with functional studies.</p

PHACTR1 genetic variability is not critical in small vessel ischemic disease patients and PcomA recruitment in C57BL/6J mice

Recently, several genome-wide association studies identified PHACTR1 as key locus for five diverse vascular disorders: coronary artery disease, migraine, fibromuscular dysplasia, cervical artery dissection and hypertension. Although these represent significant risk factors or comorbidities for ischemic stroke, PHACTR1 role in brain small vessel ischemic disease and ischemic stroke most important survival mechanism, such as the recruitment of brain collateral arteries like posterior communicating arteries (PcomAs), remains unknown. Therefore, we applied exome and genome sequencing in a multi-ethnic cohort of 180 early-onset independent familial and apparently sporadic brain small vessel ischemic disease and CADASIL-like Caucasian patients from US, Portugal, Finland, Serbia and Turkey and in 2 C57BL/6J stroke mouse models (bilateral common carotid artery stenosis [BCCAS] and middle cerebral artery occlusion [MCAO]), characterized by different degrees of PcomAs patency. We report 3 very rare coding variants in the small vessel ischemic disease-CADASIL-like cohort (p.Glu198Gln, p.Arg204Gly, p.Val251Leu) and a stop-gain mutation (p.Gln273*) in one MCAO mouse. These coding variants do not cluster in PHACTR1 known pathogenic domains and are not likely to play a critical role in small vessel ischemic disease or brain collateral circulation. We also exclude the possibility that copy number variants (CNVs) or a variant enrichment in Phactr1 may be associated with PcomA recruitment in BCCAS mice or linked to diverse vascular traits (cerebral blood flow pre-surgery, PcomA size, leptomeningeal microcollateral length and junction density during brain hypoperfusion) in C57BL/6J mice, respectively. Genetic variability in PHACTR1 is not likely to be a common susceptibility factor influencing small vessel ischemic disease in patients and PcomA recruitment in C57BL/6J mice. Nonetheless, rare variants in PHACTR1 RPEL domains may influence the stroke outcome and are worth investigating in a larger cohort of small vessel ischemic disease patients, different ischemic stroke subtypes and with functional studies

The biological function of the cellular prion protein: an update

The misfolding of the cellular prion protein (PrPC) causes fatal neurodegenerative diseases. Yet PrPC is highly conserved in mammals, suggesting that it exerts beneficial functions preventing its evolutionary elimination. Ablation of PrPC in mice results in well-defined structural and functional alterations in the peripheral nervous system. Many additional phenotypes were ascribed to the lack of PrPC, but some of these were found to arise from genetic artifacts of the underlying mouse models. Here, we revisit the proposed physiological roles of PrPC in the central and peripheral nervous systems and highlight the need for their critical reassessment using new, rigorously controlled animal models. The cellular prion protein (PrPC) is a cell surface protein expressed in a variety of different organs and tissues with high expression levels in the central and peripheral nervous systems [1]. It is mainly known for its infamous role in prion diseases, where its misfolding and aggregation cause inevitably fatal neurodegenerative conditions [2]. Prion diseases are transmissible and misfolded prion protein (PrPSc) is—according to the “protein-only hypothesis’”—the only disease-causing agent [3]. Under this view, it is puzzling that a protein underlying such severe diseases is highly conserved throughout mammals [4]. This suggests the existence of distinct benefits and, potentially, important physiological functions. A definitive, fully satisfactory understanding of the physiological function of PrPC has been lacking for a long time. Very recently, we identified a native function of PrPC in the peripheral nervous system and the underlying mechanism of that function [5]. However, PrPC is also highly expressed in the central nervous system (CNS) and its biological activity there is still far from being clear. This review will focus on the proposed roles of cellular prion protein in the central and peripheral nervous systems

Experimental analysis of evaporative emissions of ethanol-blended gasoline in automotive tanks at different temperature conditions

Automobiles are major sources of Volatile Organic Compounds (VOCs) and Very Volatile Organic Compounds (VVOCs), which are emitted not only from their tailpipes while running but also as evaporative emissions from gasoline fueled vehicle tanks and supply systems; these emissions are the main source of pollution for both standard and hybrid vehicles. VOCs and VVOCs can have significant effects on human health and environment, so emissions are subject to many regulations, both European and international, that are becoming increasingly stringent every year. In this paper, an experimental activity has been carried out to evaluate the fuel vapor generation from gasoline-filled fuel tanks. These experimental tests have been conducted by means of a Variable Temperature mini-SHED in Stellantis N.V. laboratories, at the Pomigliano Technical Center, in Italy. Different conditions of temperature and filling levels have been analyzed by monitoring the fuel vapors coming from the tank to the carbon canister. Tests have been divided in two groups with both constant and variable temperatures, by following standard temperature cycles, defined by regulations. Results are presented in terms of vapor temperature profiles and canister mass variation; they demonstrate the high influence of the environment temperature and of the filling levels on the emission

0D Modeling of Fuel Tank for Vapor Generation

Petrol vapor emissions are the main source of pollution for both standard and hybrid vehicles. They are mainly generated by gasoline evaporation from the fuel tank of both running and parked vehicles; it is mostly driven by fuel temperature variation due to daily temperature changes (if parked) and heat from engine (if running). To prevent its dispersion in the environment, the vapor generated in the fuel tank is usually stored in a carbon canister filter that must be periodically “purged” in order to prevent its saturation, by venting it to the intake manifold. Canister management, made by the Engine Control Unit (ECU), becomes even more critical for hybrid-electric vehicles because thermal engine is often off, thus purging cannot take place. A pressurized fuel tank is often used for hybrid applications, to further isolate vapor from environment, making the fuel system even more complex to model. System design optimization is usually based on experience and experimental correlations, which require time and cost. Thus, comes the need for a comprehensive predictive model useful for both vehicle components (fuel tank and carbon canister) and ECU software design. A 0D Matlab® model is proposed, which can predict vapor generation from an arbitrary tank in standard and arbitrary thermal cycles, with arbitrary tank capacity, geometry and construction and at different filling levels. It is based on a system of thermo-fluid-dynamic differential equations and semi-empirical correlations that is iteratively solved in time. Model calibration has been performed by using a small size test tank and validation has been completed on full size tanks for both standard and hybrid-electric applications. The main driving force for vapor generation has been shown to be the amount of empty volume on top of the tank; other significant effects come from tank volume, material, external surface as well as fuel properties. Ongoing work is to develop and integrate a carbon canister loading/purging model, with the aim to build a full model of the vapor system

Physical Modeling of Evaporative Emission Control System in Gasoline Fueled Automobiles: a Review

Fuel evaporative emission from a vehicle fuel tank have long been known to be an important source of pollution, and international regulation on automotive Volatile Organic Compounds (VOC) are becoming increasingly stringent every year, because of their eects on human health and environment. The most cost-eective solution for limiting the release of VOC to the environment is their adsorption by activated carbon through an evaporative canister device that is integrated in the vehicle fuel system. Analysis and development of these systems requires an in-depth study of the evaporation and the adsorption/desorption processes. Many theoretical and experimental studies have been performed during the years, and several physical models have been developed. This paper presents a state-of-the-art review of these studies, speci-cally focusing on the mathematical modeling of the evaporation phenomena and its application for describing real conditions, along with several fuel adsorption and desorption (purging) models of carbon canisters. A knowledge of the evaporation phenomena and adsorption/desorption process can lead to a better canister design and purging strategies, in order to match the vehicle emission regulations that are being adopted worldwide, in a view of sustainable mobility