A multi-targeted drug candidate with dual anti-HIV and anti-HSV activity

Human immunodeficiency virus (HIV) infection is often accompanied by infection with other pathogens, in particular herpes simplex virus type 2 (HSV-2). The resulting coinfection is involved in a vicious circle of mutual facilitations. Therefore, an important task is to develop a compound that is highly potent against both viruses to suppress their transmission and replication. Here, we report on the discovery of such a compound, designated PMEO-DAPym. We compared its properties with those of the structurally related and clinically used acyclic nucleoside phosphonates (ANPs) tenofovir and adefovir. We demonstrated the potent anti-HIV and -HSV activity of this drug in a diverse set of clinically relevant in vitro, ex vivo, and in vivo systems including (i) CD4⁺ T-lymphocyte (CEM) cell cultures, (ii) embryonic lung (HEL) cell cultures, (iii) organotypic epithelial raft cultures of primary human keratinocytes (PHKs), (iv) primary human monocyte/macrophage (M/M) cell cultures, (v) human ex vivo lymphoid tissue, and (vi) athymic nude mice. Upon conversion to its diphosphate metabolite, PMEO-DAPym markedly inhibits both HIV-1 reverse transcriptase (RT) and HSV DNA polymerase. However, in striking contrast to tenofovir and adefovir, it also acts as an efficient immunomodulator, inducing β-chemokines in PBMC cultures, in particular the CCR5 agonists MIP-1β, MIP-1α and RANTES but not the CXCR4 agonist SDF-1, without the need to be intracellularly metabolized. Such specific β-chemokine upregulation required new mRNA synthesis. The upregulation of β-chemokines was shown to be associated with a pronounced downmodulation of the HIV-1 coreceptor CCR5 which may result in prevention of HIV entry. PMEO-DAPym belongs conceptually to a new class of efficient multitargeted antivirals for concomitant dual-viral (HSV/HIV) infection therapy through inhibition of virus-specific pathways (i.e. the viral polymerases) and HIV transmission prevention through interference with host pathways (i.e. CCR5 receptor down regulation)

Numerical Modeling and Simulation of Melting Phenomena for Freeze Valve Analysis in Molten Salt Reactors

In recent years, molten salt reactors (MSRs) have gained new momentum thanks to their potential for innovation in the nuclear industry, and several studies on their compliance with all the expected safety features are currently underway. In terms of passive safety, a strategy currently envisaged in accidental scenarios is to drain by gravity the molten salt, which acts both as fuel and coolant, in an emergency draining tank, ensuring both a subcritical geometry and proper cooling. To activate the draining system, a freeze plug, made of the same salt used in the core, is expected to open when the temperature in the core reaches high values. Up to this point, the freeze valve is still a key concept in the molten salt fast reactor (MSFR), and special attention must be paid to its analysis, given the requirement for passive safety, especially focusing on melting and solidification phenomena related to the molten salt mixture. This work aims to contribute to the macroscale modeling of melting and solidification phenomena relevant to the analysis of the freeze valve behavior. In particular, the focus is on the identification of the numerical models that can be adopted to achieve the quantitative insights needed for the design of the freeze valve. Among the ones available in the literature, the most appropriate models were selected based on a compromise between accuracy and computational efficiency. A critical look at the models allows for a synthetic and consistent formulation of the numerical models and their implementation in the open-source software OpenFOAM. The code was subsequently verified using analytical and numerical solutions already well established in the literature. A good agreement between the results produced by the developed solver and the reference solutions was obtained. In the end, the code was applied to simple case studies related to the freeze valve system, focusing on recognizing whether the developed code can model physical phenomena that can occur in a freeze valve. The results of the simulations are encouraging and show that the code can be used to model single-region melting or solidification problems. As such, this work constitutes a starting point for further development of the code, intending to achieve better quantitative predictions for the design of a freeze valve

Interleukin-7 Facilitates HIV-1 Transmission to Cervico-Vaginal Tissue ex vivo

The majority of HIV-1 infections in women occur through vaginal intercourse, in which virus-containing semen is deposited on the cervico-vaginal mucosa. Semen is more than a mere carrier of HIV-1, since it contains many biological factors, in particular cytokines, that may affect HIV-1 transmission. The concentration of interleukin (IL)-7, one of the most prominent cytokines in semen of healthy individuals, is further increased in semen of HIV-1-infected men. Here, we investigated the potential role of IL-7 in HIV-1 vaginal transmission in an ex vivo system of human cervico-vaginal tissue. We simulated an in vivo situation by depositing HIV-1 on cervico-vaginal tissue in combination with IL-7 at concentrations comparable with those measured in semen of HIV-1-infected individuals. We found that IL-7 significantly enhanced virus replication in ex vivo infected cervico-vaginal tissue. Similarly, we observed an enhancement of HIV-1 replication in lymphoid tissue explants. Analysis of T cells isolated from infected tissues showed that IL-7 reduced CD4+ T cell depletion preventing apoptosis, as shown by the decrease in the number of cells expressing the apoptotic marker APO2.7 and the increase in the expression of the anti-apoptotic protein B-cell lymphoma (Bcl)-2. Also, IL-7 increased the fraction of cycling CD4+ T cells, as evidenced by staining for the nuclear factor Ki-67. High levels of seminal IL-7 in vivo may be relevant to the survival of the founder pool of HIV-1-infected cells in the cervico-vaginal mucosa at the initial stage of infection, promoting local expansion and dissemination of HIV infection

Integration of OpenCalphad thermo-chemical solver in PLEIADES/ALCYONE fuel performance code

International audienceThe ALCYONE fuel performance code, co-developed by CEA, EDF and Framatome, within the PLEIADES software environment provides a multidimensional modeling for detailed analysis of PWR fuel elements behavior under irradiation [1]. Iodine-Stress Corrosion Cracking is one of the physical phenomena of major interest for cladding design and long term operation of PWRs. In a first step towards I-SCC simulations, the thermochemical code ANGE was integrated in PLEIADES [2]. ANGE, a modified version of SOLGASMIX, enables to compute thermo-chemical equilibria using the TBASE database [3] and associate species description [4] but has some limitations and cannot be used to solve chemical systems based on the Compound Energy Formalism, such as the one proposed in the TAF-ID [5]. Consequently, a robust, efficient and free numerical tool, OpenCalphad [6], was introduced in PLEIADES. In this work, we focus our presentation on the calculation of complex multi-component systems representative of fuel elements behavior under irradiation. From the results of in-reactor power transient calculations (1D-2D-3D), we show that ALCYONE/OpenCalphad is much faster than ALCYONE/ANGE. We note a decrease of the CPU time by almost a factor 4 that can be explained by the OpenCalphad solver itself and by a set of numerical strategies implemented to start a thermodynamic calculation on a mesh node by using another calculated equilibrium as an initial solution. We also show through first results the capacity and the robustness of the ALCYONE/OpenCalphad coupling to do in-reactor power transients calculations (1D-2D-3D) using the TAF-ID. In the latter, the models are more complicated and the possible phases are greater in number than in the TBASE database. For calculations performed in the same conditions as those done with the TBASE database, we note a slight increase of the CPU time that can be reduced by calculating several thermodynamic equilibria simultaneously with a multithread approach.References[1] V. Marelle, et al. New developments in ALCYONE 2.0 fuel performance code, Top Fuel, Boise ID (2016)[2] B. Baurens, et al., J. Nucl. Mater. 452 (2014) 578[3] E.H.P. Cordfuncke, R.J.M. Konings, J. Phase Equilibria 14 [4] (1993)[4] T.M. Besmann, Comprehensive Nucl. Mater. 1.17 (2012)[5] C. Gueneau et al., J. Nucl. Mater. 419 (2011) 147[6] B. Sundman, et al, Integ. Mater. Manuf. Innov. 4 (2015)

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

In the continuous strive to improve the safety of current-generation and next-generation nuclear power plants, natural circulation can be used to design passive safety systems to remove the decay heat during the shutdown. The Molten Salt Fast Reactor (MSFR) is a peculiar type of Gen-IV nuclear facility, where the fluid fuel is homogeneously mixed with the coolant. This design leads to natural circulation in the presence of an internally distributed heat source during the shutdown. Furthermore, to shield the environment from the highly radioactive fuel, an intermediate loop between the primary and the secondary loops, able to operate in natural circulation, is required. To analyze the natural circulation with a distributed heat source and to study the natural circulation of coupled systems and the influence of the intermediate loop on the behaviour of the primary, Politecnico di Milano designed and built the DYNASTY-eDYNASTY facility. The two facilities are coupled with a double-pipe heat exchanger, which siphons heat from DYNASTY and delivers it to the eDYNASTY loop. This work focuses on modelling the coupled DYNASTY-eDYNASTY natural circulation loops using DYMOLA2023((R)), an integrated development environment based on the Modelica Object-Oriented a-causal simulation language. The 1D Modelica approach allows for building highly reusable and flexible models easing the design effort on a complex system such as the DYNASTY-eDYNASTY case without the need to rewrite the whole model from scratch. The coupled models were developed starting from the already-validated single DYNASTY model and the double-pipe heat exchanger coupling. The models were tested during the whole development process, studying the influence of the numerical integration algorithm on the simulation behaviour. A preliminary analysis of both the adiabatic and the heat loss models analyzed the effect of the secondary natural circulation loop on the behaviour of the DYNASTY loop. The simulation results showed that the eDYNASTY loop dampens the behaviour of the primary DYNASTY loop. Furthermore, a parametric analysis of the DYNASTY and the eDYNASTY coolers highlighted the influence of the cooling configuration on the facility's behaviour. Finally, the simulation results identified the most critical aspects of the models in preparation for an experimental comparison

Bidirectional Modulation of Alcohol-Associated Memory Reconsolidation through Manipulation of Adrenergic Signaling.

Alcohol addiction is a problem of great societal concern, for which there is scope to improve current treatments. One potential new treatment for alcohol addiction is based on disrupting the reconsolidation of the maladaptive Pavlovian memories that can precipitate relapse to drug-seeking behavior. In alcohol self-administering rats, we investigated the effects of bidirectionally modulating adrenergic signaling on the strength of a Pavlovian cue-alcohol memory, using a behavioral procedure that isolates the specific contribution of one maladaptive Pavlovian memory to relapse, the acquisition of a new alcohol-seeking response for an alcohol-associated conditioned reinforcer. The β-adrenergic receptor antagonist propranolol, administered in conjunction with memory reactivation, persistently disrupted the memory that underlies the capacity of a previously alcohol-associated cue to act as a conditioned reinforcer. By contrast, enhancement of adrenergic signaling by administration of the adrenergic prodrug dipivefrin at reactivation increased the strength of the cue-alcohol memory and potentiated alcohol seeking. These data demonstrate the importance of adrenergic signaling in alcohol-associated memory reconsolidation, and suggest a pharmacological target for treatments aiming to prevent relapse through the disruption of maladaptive memories.This work was supported by a UK Medical Research Council Programme Grant (G1002231) to BJE and ALM and was conducted in the Behavioural and Clinical Neuroscience Institute (BCNI), an initiative jointly funded by the MRC and the Wellcome Trust. MJWS was supported by an MRC Doctoral Training Grant and the James Baird Fund at the Medical School of the University of Cambridge. ALM was partly supported by a BCNI lectureship and the Ferreras-Willetts Fellowship from Downing College, Cambridge.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/npp.2015.24

Ex vivo infection of human lymphoid tissue and female genital mucosa with human immunodeficiency virus 1 and histoculture

Histocultures allow studying intercellular interactions within human tissues, and they can be employed to model host-pathogen interactions under controlled laboratory conditions. Ex vivo infection of human tissues with human immunodeficiency virus (HIV), among other viruses, has been successfully used to investigate early disease pathogenesis, as well as a platform to test the efficacy and toxicity of antiviral drugs. In the present protocol, we explain how to process and infect with HIV-1 tissue explants from human tonsils and cervical mucosae, and maintain them in culture on top of gelatin sponges at the liquid-air interface for about two weeks. This non-polarized culture setting maximizes access to nutrients in culture medium and oxygen, although progressive loss of tissue integrity and functional architectures remains its main limitation. This method allows monitoring HIV-1 replication and pathogenesis using several techniques, including immunoassays, qPCR, and flow cytometry. Of importance, the physiologic variability between tissue donors, as well as between explants from different areas of the same specimen, may significantly affect experimental results. To ensure result reproducibility, it is critical to use an adequate number of explants, technical replicates, and donor-matched control conditions to normalize the results of the experimental treatments when compiling data from multiple experiments (i.e., conducted using tissue from different donors) for statistical analysis

Development of an OpenFOAM multiphysics solver for solid fission products transport in the Molten Salt Fast Reactor

The analysis of innovative reactor concepts such as the Molten Salt Fast Reactor (MSFR) requires the development of new modeling and simulation tools. In the case of the MSFR, the strong intrinsic coupling between thermal-hydraulics, neutronics and fuel chemistry has led to the adoption of the multiphysics approach as a state-of-the-art paradigm. One of the peculiar aspects of liquid-fuel reactors such as the MSFR is the mobility of fission products (FPs) in the reactor circuit. Some FP species appear in form of solid precipitates carried by the fuel flow and can deposit on reactor boundaries (e.g., heat exchangers), potentially representing design issues related to the degradation of heat exchange performance or radioactive hotspots. The integration of transport models for solid particles in multiphysics codes is therefore relevant for the prediction of deposited fractions. To this aim, we develop a multiphysics solver based on the OpenFOAM library to address the issue of solid fission products transport. Single-phase incompressible thermal hydraulics are coupled with neutron diffusion, and advection-diffusion-decay equations are implemented for fission products concentrations. Particle deposition and precipitation are considered as well. The developed solver is tested on two different MSFR application to showcase the capabilities of the solver in steady-state simulation and to investigate the role of precipitation and turbulence modeling in the determination of particle concentration distributions

CD49a Expression Defines Tissue-Resident CD8+ T Cells Poised for Cytotoxic Function in Human Skin

Tissue-resident memory T (Trm) cells form a heterogeneous population that provides localized protection against pathogens. Here, we identify CD49a as a marker that differentiates CD8(+) Trm cells on a compartmental and functional basis. In human skin epithelia, CD8(+)CD49a(+) Trm cells produced interferon-γ, whereas CD8(+)CD49a(−) Trm cells produced interleukin-17 (IL-17). In addition, CD8(+)CD49a(+) Trm cells from healthy skin rapidly induced the expression of the effector molecules perforin and granzyme B when stimulated with IL-15, thereby promoting a strong cytotoxic response. In skin from patients with vitiligo, where melanocytes are eradicated locally, CD8(+)CD49a(+) Trm cells that constitutively expressed perforin and granzyme B accumulated both in the epidermis and dermis. Conversely, CD8(+)CD49a(–) Trm cells from psoriasis lesions predominantly generated IL-17 responses that promote local inflammation in this skin disease. Overall, CD49a expression delineates CD8(+) Trm cell specialization in human epithelial barriers and correlates with the effector cell balance found in distinct inflammatory skin diseases

Grain-Scale Modeling of Active Fission Product Behavior During Power Ramps with the Fission Gas Model MARGARET-PAF

Due to their influence on the general behavior of the fuel rod, fission gases in oxide fuels are a major topic of research in the nuclear community. Fuel swelling, thermal conductance degradation of the fuel-cladding gap, and over-pressurization of the fuel rod belong to the potential negative impacts of fission gases during irradiation. The fission gas model MARGARET has been developed by the CEA for many years, and takes into account relevant phenomena related to inert fission gas (xenon and krypton) behavior in nuclear fuels, at the grain scale. MARGARET has been included in fuel performance simulations, and in particular in ALCYONE, the code co-developed by the CEA, EDF, and FRAMATOME within the PLEIADES computational environment. The MARGARET model is mainly used to evaluate the release of inert fission gases during normal or incidental loading sequences. In recent years, the calculated noble gases percolation flux has been employed to assess the release of the minor and chemically reactive fission gases (mostly iodides) from the fuel pellet during slow power transients. This approach was however limited to long- lived fission products, and considered that they were immediately available on grain boundaries. In order to overpass these two limitations, a sub-model of MARGARET, called MARGARET-PAF, have been coupled to thermochemistry and used. MARGARET-PAF calculates the production, disappearance, and transport of a whole series of isotopes (mainly xenon, krypton, iodine, cesium, tellurium, and strontium) in the fuel. MARGARET-PAF uses all the microstructural quantities calculated by MARGARET, which may influence active fission product transport, such as intra- and inter-granular bubble concentrations (in the grain and at grain boundaries) and material restructuring (High Burnup Structure formation). In this study, the model undergoes validation through the simulation of a power transient, replicating an experiment conducted on a refabricated irradiated fuel rod within the OSIRIS experimental reactor. The simulation is conducted using the code stand-alone and input data (temperature, pressure) previously computed by the fuel performance code ALCYONE. Simulation results are discussed and compared to available experimental data