83 results on '"Marchitto L"'
Search Results
2. 3D structure of liquid sprays: X-ray [formula omitted]-radiography and tomography by polycapillary based technique
- Author
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Marchitto, L., Allocca, L., Hampai, D., Alfuso, S., Dabagov, S.B., Liedl, A., and Polese, C.
- Published
- 2015
- Full Text
- View/download PDF
3. Combustion process investigations in an optically accessible DISI engine fuelled with n-butanol during part load operation
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Irimescu, A., Marchitto, L., Merola, S.S., Tornatore, C., and Valentino, G.
- Published
- 2015
- Full Text
- View/download PDF
4. GDI spray structure analysis by polycapillary X-ray [formula omitted]-tomography
- Author
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Marchitto, L., Hampai, D., Dabagov, S.B., Allocca, L., Alfuso, S., Polese, C., and Liedl, A.
- Published
- 2015
- Full Text
- View/download PDF
5. Study of mixture formation and early flame development in a research GDI (gasoline direct injection) engine through numerical simulation and UV-digital imaging
- Author
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Costa, M., Marchitto, L., Merola, S.S., and Sorge, U.
- Published
- 2014
- Full Text
- View/download PDF
6. Combustion process investigation in a high speed diesel engine fuelled with n-butanol diesel blend by conventional methods and optical diagnostics
- Author
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Merola, S.S., Tornatore, C., Iannuzzi, S.E., Marchitto, L., and Valentino, G.
- Published
- 2014
- Full Text
- View/download PDF
7. Desktop X-ray tomography for low contrast samples
- Author
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Hampai, D., Marchitto, L., Dabagov, S.B., Allocca, L., Alfuso, S., and Innocenti, L.
- Published
- 2013
- Full Text
- View/download PDF
8. Optical Analysis of Combustion and Soot Formation in a CI Engine Fuelled with Water in Diesel Emulsion through Microchannels Emulsification
- Author
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Tornatore, C, primary, Calabria, R, additional, Marchitto, L, additional, Belletre, J, additional, Massoli, P, additional, Montillet, A, additional, and Valentino, G, additional
- Published
- 2018
- Full Text
- View/download PDF
9. Optical investigations in a CI engine fueled with water in diesel emulsion produced through microchannels
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Marchitto, L., primary, Calabria, R., additional, Tornatore, C., additional, Bellettre, J., additional, Massoli, P., additional, Montillet, A., additional, and Valentino, G., additional
- Published
- 2018
- Full Text
- View/download PDF
10. Water Spray Flow Characteristics Under Synthetic Jet Driven By a Piezoelectric Actuator
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Marchitto, L., primary, Valentino, G., additional, Chiatto, M., additional, and de Luca, L., additional
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- 2017
- Full Text
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11. GDI spray structure analysis by polycapillary X-ray μ-tomography
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Marchitto, L.
- Subjects
AAM ,20152019VQR - Abstract
A X-ray μ-tomography technique, using a Cu Kα source at 8.048. keV coupled with both polycapillary optics and CCD detector, has been developed to reconstruct the composition of a transient gasoline spray generated by a high-pressure GDI injector for automotive applications. The polycapillary elements enable shaping the divergent beams and getting high-contrast images due to the suppression of radiation multiple scattering. A pressure-tight device permits the 360° rotation of a six-hole nozzle, with a step of 0.1°, at injection pressures up to 20. MPa, while the spray plume develops in a vented Plexiglas chamber at the atmospheric backpressure. The entire system is configured as a table-top experiment. The extinction images acquired along the X-ray source-spray-detector line-of-sight have permitted the reconstruction of a 3D structure together with a morphology of the jets within a 3. mm region downstream the nozzle. The spray shape as well as the propagation direction can be clearly identified in the tomographic reconstruction for all the six jets. Quantitative measurements of the fuel mass density in the near nozzle region have been performed. Typical Gaussian-shape distribution of the intensities appears for the cross sections revealing the more dense jet regions in the core, while slight longitudinal asymmetries indicate an interaction between the jet plumes.
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- 2015
- Full Text
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12. Dense spray imaging and tomography by Polycapillary X-ray Technique
- Author
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Marchitto, L., Allocca, L., Hampai, D., Dabagov, S., Alfuso, S., Liedl, A., and Polese, Claudia
- Published
- 2014
13. Experimental investigation of combustion processes in an optical DISI engine equipped with plasma-assisted ignition system
- Author
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Irimescu A., Marchitto L., Merola S.S., Tornatore C., Valentino G., Silva S., and Grimaldi A.
- Subjects
DI engine ,Superficial charge plug ,Plasma-assisted ignition ,Flame front propagation ,Optical diagnostics ,Physics::Chemical Physics - Abstract
Currently, direct injection for gasoline engines is a primary trend for improving the efficiency allowing to reduce fuel consumption and meet stringent emission standards. A large temporal and spatial variation of mixture composition near the spark location during low speed and high load operation are driving the demands for significantly improved ignition systems. Recently, plasma-assisted ignition systems received increasing interest, they are used for combustion initiation and control and show the potential for flame stabilization. The aim of this paper is to improve the understanding of the processes related to the use of a plasma-assisted ignition system and its influence on combustion development. Experiments were performed in an optical SI engine equipped with the cylinder head and injection system of a commercial SI turbocharged engine. The effect of the spark plug geometry and of the plasma configurations were investigated. UV-visible digital imaging was applied. The optical data were correlated to in-cylinder pressure-based data and exhaust emission measurements. Significantly higher stability, quantified through the coefficients of variation of IMEP and of flame radius, was obtained using the alternative ignition system. An improvement in engine performance and pollutant emissions was achieved.
- Published
- 2013
14. X-ray refraction 3D-simulation software: First approach
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Allocca L. 1, Dabagov S.B. 2-3, and Marchitto L. 1
- Abstract
In this work preliminary results on simulation of X-ray propagation in media characterized by low index of both refraction and absorption are reported. A 3D simulation software reproduces parallel X-ray beam colliding the samples while the emerging field distribution is evaluated at the detector place. The simulation code has been structured in order to foresee the different nature of investigating samples and transmitting media. The pictures of the emerging radiation, collected at the detector position, show a good sensibility of the software with respect to the sample parameters pointing it out as a powerful tool to set up arrangements of complex experimental apparatus. The first approach has proved the feasibility of typical Math code application for the analysis of X-ray imaging measurements performed by means of high-flux and low-divergent beams shaped by polycapillary half lens.
- Published
- 2011
15. Optical investigation of the effect on the combustion process of butanol-gasoline blend in a PFI SI boosted engine
- Author
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Merola S.S., Tornatore C., Valentino G., Marchitto L., and Esposito Corcione F.
- Abstract
The addition of alcohol to conventional hydrocarbon fuels for a spark-ignition engine can increase the fuel octane rating and the power for a given engine displacement and compression ratio. In this work, the influence of butanol addition to gasoline was investigated. The experiments were performed in an optical ported fuel injection single cylinder SI engine with an external boosting device. The engine was equipped with the head of a commercial SI turbocharged engine having the same geometrical specifications (bore, stroke and compression ratio). The effect of a blend of 20% of n-butanol and 80% of gasoline (BU20) on in-cylinder combustion process was investigated by cycle resolved visualization. The engine worked at low speed, medium boosting and wide open throttle. Changes in spark timing and fuel injection phasing were considered. Comparisons between the flame luminosity and the combustion pressure data were performed. The fuel was injected both at closed intake valve (CV) and open intake valve (OV). The spark timing was changed to identify the maximum brake torque and the knocking limit. Butanol blend allowed working in more advanced spark timing without occurrence of abnormal combustion. For the blend BU20, the duration of injection (DOI) was increased to obtain a stoichiometric mixture. For both fuels, at stoichiometric conditions, DOI in OV was maintained shorter than that in CV, due to the lower amount of fuel deposited on intake port and on piston surface. The combustion images showed a different combustion behavior injecting the fuel in CV and in OV conditions. In OV condition, several light spots were observed in the flame front region due to the condensed fuel attached on the optical piston wall. In CV condition, the light spots are bigger but less in number than in OV condition. For BU20 the previous phenomena were less evident due to the chemical composition of the blend that reduces the amount of fuel attached to the piston wall. For both fuels and at all engine conditions, a low variation of IMEP was observed (
- Published
- 2011
16. Effect of butanol blend on in-cylinder combustion process. Part 1: spark ignition engine
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Tornatore C., Marchitto L., Mazzei A., Valentino G., Esposito Corcione F., and Merola S.S.
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PFI SI boosted engine ,Combustion process ,Optical diagnostics ,Butanol-gasoline blend - Published
- 2011
17. Evaluation of soot and flame lift-off length in a high swirl optically accessed Diesel engine
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Esposito Corcione F., Iannuzzi S., Marchitto L., Merola S.S., and Valentino G.
- Published
- 2011
18. Effect of butanol blend on in-cylinder combustion process. Part 2: compression ignition engine
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Tornatore C., Marchitto L., Mazzei A., Valentino G., Esposito Corcione F., and Merola S.S.
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Common rail CI engine ,Combustion process ,Diesel/gasoline blend ,Diesel/butanol blend ,Optical diagnostics - Published
- 2011
19. Efectul asupra procesului de ardere al amestecurilor de benzina/motorina si n-butanol/motorina la un motor cu aprindere prin comprimare cu vizualizare optica
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Tornatore C., Marchitto L., Mazzei A., Valentino G., Esposito Corcione F., and Merola S.S.
- Abstract
Effect on combustion process of gasoline/diesel and n-butanol/diesel blends in an optical compression ignition engine. To meet the future stringent emission standards, innovative diesel engine technology, exhaust gas after-treatment, and clean alternative fuels are required. Oxygenated fuels have showed a tendency to decrease internal combustion engine emissions. In the same time, advanced fuel injection modes can promote a further reduction of the pollutants at the exhaust without penalty for the combustion efficiency. One of the more interesting solutions is provided by the premixed low temperature combustion (PLTC) mechanism jointly to lower-cetane, higher-volatility fuels. To understand the role played by these factors on soot formation, optical techniques and were applied in a high swirl multi-jets compression ignition engine. Combustion tests were carried out using three fuels: commercial diesel, a blend of 80% diesel with 20% gasoline (G20) and a blend of 80% diesel with 20% n-butanol (BU20). The fuels were tested at 70MPa injection pressure and different timings using an open Common Rail injection system. At late injection timing coupled to high EGR rate (50%), the blends increased the ignition delay allowing to operate in partially premixed LTC (PPLTC) regime in which the fuel is completely injected before the start of combustion. Strong reduction of engine out emissions of smoke and NOx were obtained but with a little penalty on engine efficiency. This limitation was overcome operating at earlier injection timing in which a mixing controlled combustion (MCC) LTC regime was realized. In this regime, a good compromise between low engine out emissions and efficiency was achieved.
- Published
- 2011
20. 3D structure of liquid sprays: X-ray μ-radiography and tomography by polycapillary based technique
- Author
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Marchitto, L., primary, Allocca, L., additional, Hampai, D., additional, Alfuso, S., additional, Dabagov, S.B., additional, Liedl, A., additional, and Polese, C., additional
- Published
- 2015
- Full Text
- View/download PDF
21. Combustion Process Analysis in a DISI Engine Fuelled with N-Butanol through UV-VIS Emission Spectroscopy
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Tornatore, C., primary, rimescu, A., additional, Marchitto, L., additional, Merola, S. S., additional, and Valentino, G., additional
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- 2015
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22. GDI spray structure analysis by polycapillary X-ray μ-tomography
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Marchitto, L., primary, Hampai, D., additional, Dabagov, S.B., additional, Allocca, L., additional, Alfuso, S., additional, Polese, C., additional, and Liedl, A., additional
- Published
- 2015
- Full Text
- View/download PDF
23. X-Ray Refraction 3D-Simulation Software: First Approach
- Author
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Marchitto L., Allocca L., Hapai D., and Dabagov S.B.
- Subjects
Astrophysics::High Energy Astrophysical Phenomena - Abstract
In this work preliminary results on simulation of X-ray propagation in media characterized by low index of both refraction and absorption. First approach has proved the feasibility of typical Math code application for the analysis of X-ray imaging measurements performed by means of high-flux and low-divergent beams shaped by polycapillary half lens.
- Published
- 2010
- Full Text
- View/download PDF
24. Gasoline Spray Imaging By Polycapillary X-Ray Technique
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Allocca, L., primary, Marchitto, L., additional, Alfuso, S., additional, Hampai, D., additional, Cappuccio, G., additional, Dabagov, S. B., additional, Denecke, Melissa, additional, and Walker, Clive T., additional
- Published
- 2010
- Full Text
- View/download PDF
25. Gasoline Spray Imaging By Polycapillary X-Ray Technique.
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Allocca, L., Marchitto, L., Alfuso, S., Hampai, D., Cappuccio, G., and Dabagov, S. B.
- Subjects
- *
GASOLINE , *X-ray spectroscopy , *IMAGING systems , *RESEARCH institutes , *ABSORPTION - Abstract
First use of a Cu X-ray source in combination with polycapillary halflens (or semilens) and a Photonic Science CCD detector for investigating highly dense jet injection sprays are reported. It is shown that in the energy range used the absorption signal is above the background level indicating but interaction of the beam with the fuel is weak. These preliminary results offers new research opportunities within various Italian research centers. [ABSTRACT FROM AUTHOR]
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- 2010
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26. 1D numerical study on hydrogen injection enabling ultra-lean combustion in a small gasoline Spark Ignition engine
- Author
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Teodosio Luigi, Pirrello Dino, and Marchitto Luca
- Subjects
Environmental sciences ,GE1-350 - Abstract
This paper deals with the effects of hydrogen port injection on combustion evolution, efficiency and exhaust emissions of a small turbocharged gasoline Spark-Ignition engine through a 1D numerical code. First, the experiments on the base engine architecture are performed at different speeds and at low/medium loads. The experimental findings are used to validate a 1D model of the whole engine, developed within a commercial code. 1D model is also refined with “user-defined” sub-models for an accurate description of the in-cylinder phenomena, namely turbulence, combustion, heat transfer, and emissions. In a second step, 1D model is virtually modified through the installation of an hydrogen injector in each intake runner, while the combustion sub-model also accounts for the impact of hydrogen addition on the laminar flame speed through a dedicated correlation. 1D simulations are performed at low/medium loads and fixed speed of 2250 rpm with 5% of hydrogen by volume in the intake air. Numerical investigations show that hydrogen addition to gasoline/air mixtures allows relevant efficiency benefits (up to a maximum percent gain of 19%), while the NO emissions are almost eliminated. Consequently, hydrogen-boosted combustion represents a potential solution to achieve very high efficiency and reduced pollutant emissions of gasoline spark ignition engines equipped with a conventional combustion system.
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- 2020
- Full Text
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27. Experimental investigations of the combustion process of n-butanol/diesel blend in an optical high swirl CI engine
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Merola, S. S., Valentino, G., Cinzia Tornatore, Marchitto, L., and Corcione, F. E.
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Common Rail CI engine ,Combustion process ,Diesel/butanol blend ,Optical diagnostics ,UV-visible spectroscopy - Abstract
In diesel engines, fuel is injected into the engine cylinder close to the end of the compression stroke. During a phase known as ignition delay, the fuel spray atomizes into small droplets, vaporizes, and mixes with air. As the piston continues moving towards TDC, the mixture temperature reaches the fuel ignition point, causing instantaneous ignition of some pre-mixed amount of fuel and air. The balance of fuel that does not burn in premixed combustion is consumed in the rate-controlled combustion phase, also known as diffusion combustion. Fuel composition, charge dilution, injection pressure as well as injection timing are the main factors that influence combustion and emission formation in the compression ignition engine. In order to evaluate the effects of these factors on in-cylinder spray combustion and soot formation, UV-visible digital imaging and natural emission spectroscopy were applied in a single cylinder high swirl compression ignition engine. The engine was optically accessible and equipped with a common rail multi-jets injection system. Combustion tests were carried out using commercial diesel and a blend of 80% diesel with 20% n-butanol (BU20). Two injection pressures (70 and 140 MPa), two injection timings (11 CAD BTDC and 3 CAD BTDC) and a low and high EGR rate were tested. UV-visible emission spectroscopy was used for the detection of the chemical markers of combustion process. Chemiluminescence signals, due to OH, HCO and CO2 emission bands were detected. OH emission was correlated to NO measured at the exhaust. The soot spectral feature in the visible wavelength range was correlated to soot engine out emissions.
28. Optimization of the performance of a GDI engine under lean conditions: An experimental and numerical study
- Author
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Costa, M., Marchitto, L., SIMONA SILVIA MEROLA, and Sorge, U.
- Subjects
Computational Fluid Dynamics Optimization ,3D Engine Model ,Fuel Efficiency ,UV-Visible Emission Spectroscopy ,Gasoline Direct Injection Engine - Abstract
Split injection events are being considered also in gasoline direct injection (GDI) engines. Under some regimes, they are already employed to increase the temperature and maximize the efficiency of the catalytic converter or to reduce the engine tendency to knock-ing. Alternatively, under moderate or low loads and speeds, split injection may be adopted for properly stratifying the air-to-fuel ratio around the spark plug. Due to the complexity of the in-cylinder phenomena, the start of injection (SOI) and the dwell time between the injection events must be correctly chosen in conjunction with the time of spark advance. This last is well known as strongly affecting the rate of heat release when all the other relevant variables are kept constant. Therefore, the solution of an optimization problem can be considered as a viable way to achieve the task of engine efficiency maximization. The effect of the synchronization of multiple injection events and spark advance within the engine working cycle is studied into detail in the present work through computational fluid dynamics optimization. An experimental and numerical characterization of the energy conversion process taking place in a GDI engine equipped with a multi-hole high-pressure injector is first performed. The engine under study is a single cylinder research DISI (Direct Injection Spark Ignition) engine mounting the same injection system of a commercial turbocharged engine. Tests are carried out using commercial gasoline. The injection duration is fixed in order to obtain lean combustion conditions. A 3D engine model is developed within the AVL FireTM environment. An in-house developed sub-model allows simulating the spray dynamics under various injection strategies. Pollut-ants formation is also considered and assessed by comparison with the measurements of ma-jor harmful species at the exhaust. After validation, the 3D engine model is coupled with a multi-objective optimization software, that employs a genetic algorithm to select the value of the input variables in the design of ex-periment (DOE space), and point out the solution better fulfilling prescribed objectives of power output and pollutants amount at the exhaust.
29. GDI multi-hole injector: Particle size and velocity distribution for single and jet-to-jet evolution analysis
- Author
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Allocca, L., Alfuso, S., Marchitto, L., and Gerardo Valentino
30. Exploring the potentials of water injection to improve fuel consumption and torque in a small displacement PFI spark-ignition engine
- Author
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Marco Piras, Luigi Teodosio, Cinzia Tornatore, Luca Marchitto, Fabio Bozza, Piras, M., Teodosio, L., Tornatore, C., Marchitto, L., and Bozza, F.
- Subjects
History ,Fuel Technology ,Polymers and Plastics ,General Chemical Engineering ,Organic Chemistry ,Energy Engineering and Power Technology ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
31. Experimental and 1D Numerical Investigations on the Exhaust Emissions of a Small Spark Ignition Engine Considering the Cylinder-by-Cylinder Variability
- Author
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Luca Marchitto, Fabio Bozza, Gerardo Valentino, Cinzia Tornatore, Luigi Teodosio, Marchitto, L., Teodosio, L., Tornatore, C., Valentino, G., and Bozza, F.
- Subjects
Physics::Fluid Dynamics ,Materials science ,law ,Spark-ignition engine ,Mechanics ,1D numerical investigation ,turbocharged spark ignition engine ,cylinder-to-cylinder variability ,Cylinder (engine) ,law.invention - Abstract
This paper reports a numerical and experimental analysis on a twin-cylinder turbocharged Spark Ignition engine carried out to investigate the cylinder-to-cylinder variability in terms of performance, combustion evolution and exhaust emissions. The engine was tested at 3000 rpm in 20 different steady-state operating conditions, selected with the purpose of observing the influence of cylinder-by-cylinder A/F ratio variations and the EGR effects on the combustion process and exhaust emissions for low to medium/high loads. The experimental outcomes showed relevant differences in the combustion evolution (characteristic combustion angles) between cylinders and not negligible variations in the emissions of the single cylinder exhaust and the overall engine one. This misalignment resulted to be due to differences in the injected fuel amount by the port injectors in the two cylinders, mainly deriving from the specific fuel rail geometry. The experimental data were then used to validate a 1D engine model, integrated with refined sub-models of turbulence, combustion, heat transfer and emissions. The model takes into account the in-cylinder production of noxious species, and their propagation in the exhaust system, up to the three-way catalytic converter. A satisfactory accuracy was reached in reproducing the overall engine performance and the combustion process in the two cylinders. In particular, the emission sub-models confirmed that the variations of the cylinder-out exhaust emissions (NOx, HC and CO) were mainly due to the non-uniform effective in-cylinder A/F ratio. The proposed numerical methodology has the potential to highlight unexpected combustion non-uniformities among different cylinders and represents a powerful support to the engine design and development. It also allows for the prediction of the overall exhaust emissions at different engine operating conditions up to the entire domain, thus assisting the engine calibration phase and reducing the experimental efforts.
- Published
- 2020
32. Desktop X-ray tomography for low contrast samples
- Author
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Dariush Hampai, S. Alfuso, Luca Marchitto, Sultan B. Dabagov, L. Allocca, Luca Innocenti, Hampai, D., Marchitto, L., Dabagov, S.B., Allocca, L., Alfuso, S., and Innocenti, L.
- Subjects
Micro tomography ,Nuclear and High Energy Physics ,business.industry ,X-ray ,Phase-contrast imaging ,Synchrotron radiation ,Radiation ,Settore FIS/03 - Fisica Della Materia ,Optics ,Signal-to-noise ratio ,Transmission (telecommunications) ,Fuel injection ,x ray tomography ,Medical imaging ,Tomography ,Polycapillary optics ,X-ray fast imaging ,business ,Instrumentation - Abstract
Based on the experience in the use of polycapillary optical systems, recently XLab Frascati LNF and IM CNR have been strongly involved in studying the techniques for high resolution X-ray Imaging and micro-tomography that intends in the development of a new imaging instrument to examine low contrast samples complicated by fast developing processes. In order to get the reliable signal to noise ratio, typically available via synchrotron radiation (SR) dedicated X-ray optical devices, for the desktop solutions we have to increase the radiation fluxes from conventional sources. As known, manipulated through polycapillary optics beams result in getting higher fluxes with respect to a pin-hole (with a gain factor of 102–103). Moreover, polycapillary semi lenses can provide low divergent beams comparable by the divergence with synchrotron radiation beams (mrad order). These features make possible the realization of high resolution imaging of low contrast samples in the transmission mode without various algorithmic processes as typically done, for instance, for phase contrast imaging. This work presents the results on X-ray micro tomography for both static biological and fast dynamic samples as well as a possible future development of a polycapillary-based experimental layout for biomedical imaging diagnostics, for the studies in material and environmental sciences, for diagnostics of hi-tech samples, etc.
- Published
- 2013
33. Experimental characterization of spray water controlled by a synthetic jet
- Author
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L.Marchitto, G.Valentino, M.Chiatto, L. de Luca, L. Marchitto, G. Valentino, M. Chiatto, L. de Luca, Marchitto, L., Valentino, G., Chiatto, Matteo, and DE LUCA, Luigi
- Subjects
Physics::Fluid Dynamics ,PIV & PDA Techniques ,Synthetic jets ,Flow control ,Liquid Sprays - Abstract
The paper reports results of an experimental investigation to explore the potential of a synthetic jet (SJ) actuator to control a water spray. Particle Image Velocimetry (PIV) and Phase Doppler Anemometry (PDA) have been applied to characterize, in terms of velocity vector distribution and droplets size, the spray behavior generated by a misting nozzle for humidification under the control of a piezo-element driven synthetic jet. Experiments have been conducted under atmospheric conditions within a chamber test rig equipped with optical accesses, allowing PIV and PDA measurements, and a water misting nozzle driven by a pressure control module. Water has been used as working liquid, investigating the jet action on the water droplets velocity vector distribution and droplets size generated by the nozzle. Tests have been carried out for two injection pressures, namely 5 and 10 MPa. For a certain reference relative position of the SJ orifice, set at 45° with respect to the water nozzle axis, investigation has been performed for three different orifice axial positions and for each operative condition tests have been replicated two-times, with and without the synthetic jet activation. PIV measurements have been taken on 300 realizations and an averaging procedure was applied to provide the velocity vector maps, whereas the number of samples acquired for the PDA tests, performed on different locations, has been set in the order of 105. The two resulting velocity vector maps and the droplets size have been compared and a statistical analysis of the jet effect on the spray velocity magnitude has been carried out. For each operative condition, the influence region of the SJ device on the spray has been computed through a T-Test algorithm. The synthetic jet interacts with the spray locally, energizing the region downstream the impact. The effect of the actuator decreases at higher injection pressures and moving the impact region upwards. Droplets coalescence can be detected along the synthetic jet axis, while no significant variations are observed along a direction orthogonal to it.
- Published
- 2016
34. Water Spray Flow Characteristics Under Synthetic Jet Driven By a Piezoelectric Actuator
- Author
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Luca Marchitto, Matteo Chiatto, L. de Luca, Gerardo Valentino, Marchitto, L., Valentino, G., Chiatto, Matteo, and DE LUCA, Luigi
- Subjects
Spray characteristics ,History ,Materials science ,Meteorology ,Nozzle ,Flow (psychology) ,02 engineering and technology ,01 natural sciences ,010305 fluids & plasmas ,Education ,Spray nozzle ,Active Flow Control ,Phase Doppler Anemometry ,0103 physical sciences ,Water spray ,Coalescence (physics) ,Mechanics ,021001 nanoscience & nanotechnology ,water spray, synthetic jet, flow control ,Computer Science Applications ,Particle Image Velocimetry ,Particle image velocimetry ,Synthetic Jet ,Synthetic jet ,0210 nano-technology ,Body orifice - Abstract
Particle Image Velocimetry (PIV) and Phase Doppler Anemometry (PDA) have been applied to investigate the droplets size and velocity distribution of a water spray, under the control of a piezo-element driven synthetic jet (SJ). Tests were carried out under atmospheric conditions within a chamber test rig equipped with optical accesses at two injection pressures, namely 5 and 10 MPa, exploring the variation of the main spray parameters caused by the synthetic jet perturbations. The SJ orifice has been placed at 45° with respect to the water spray axis; the nozzle body has been moved on its own axis and three different nozzle quotes were tested. PIV measurements have been averaged on 300 trials whereas about 105 samples have been acquired for the PDA tests. For each operative condition, the influence region of the SJ device on the spray has been computed through a T-Test algorithm. The synthetic jet locally interacts with the spray, energizing the region downstream the impact. The effect of the actuator decreases at higher injection pressures and moving the impact region upwards. Droplets coalescence can be detected along the synthetic jet axis, while no significant variations are observed along a direction orthogonal to it.
- Published
- 2017
35. The combination of three CD4-induced antibodies targeting highly conserved Env regions with a small CD4-mimetic achieves potent ADCC activity.
- Author
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Marchitto L, Richard J, Prévost J, Tauzin A, Yang D, Chiu T-J, Chen H-C, Díaz-Salinas MA, Nayrac M, Benlarbi M, Beaudoin-Bussières G, Anand SP, Dionne K, Bélanger É, Chatterjee D, Medjahed H, Bourassa C, Tolbert WD, Hahn BH, Munro JB, Pazgier M, Smith AB 3rd, and Finzi A
- Abstract
The majority of naturally elicited antibodies against the HIV-1 envelope glycoproteins (Env) are non-neutralizing (nnAbs) because they are unable to recognize the Env trimer in its native "closed" conformation. Nevertheless, it has been shown that nnAbs have the potential to eliminate HIV-1-infected cells by antibody-dependent cellular cytotoxicity (ADCC) provided that Env is present on the cell surface in its "open" conformation. This is because most nnAbs recognize epitopes that become accessible only after Env interaction with CD4 and the exposure of epitopes that are normally occluded in the closed trimer. HIV-1 limits this vulnerability by downregulating CD4 from the surface of infected cells, thus preventing a premature encounter of Env with CD4. Small CD4-mimetics (CD4mc) sensitize HIV-1-infected cells to ADCC by opening the Env glycoprotein and exposing CD4-induced (CD4i) epitopes. There are two families of CD4i nnAbs, termed anti-cluster A and anti-CoRBS Abs, which are known to mediate ADCC in the presence of CD4mc. Here, we performed Fab competition experiments and found that anti-gp41 cluster I antibodies comprise a major fraction of the plasma ADCC activity in people living with HIV (PLWH). Moreover, addition of gp41 cluster I antibodies to cluster A and CoRBS antibodies greatly enhanced ADCC-mediated cell killing in the presence of a potent indoline CD4mc, CJF-III-288. This cocktail outperformed broadly neutralizing antibodies and even showed activity against HIV-1-infected monocyte-derived macrophages. Thus, combining CD4i antibodies with different specificities achieves maximal ADCC activity, which may be of utility in HIV cure strategies.IMPORTANCEThe elimination of HIV-1-infected cells remains an important medical goal. Although current antiretroviral therapy decreases viral loads below detection levels, it does not eliminate latently infected cells that form the viral reservoir. Here, we developed a cocktail of non-neutralizing antibodies targeting highly conserved Env regions and combined it with a potent indoline CD4mc. This combination exhibited potent ADCC activity against HIV-1-infected primary CD4 + T cells as well as monocyte-derived macrophages, suggesting its potential utility in decreasing the size of the viral reservoir.
- Published
- 2024
- Full Text
- View/download PDF
36. Three families of CD4-induced antibodies are associated with the capacity of plasma from people living with HIV to mediate ADCC in the presence of CD4-mimetics.
- Author
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Tauzin A, Marchitto L, Bélanger É, Benlarbi M, Beaudoin-Bussières G, Prévost J, Yang D, Chiu T-J, Chen H-C, Bourassa C, Medjahed H, Korzeniowski MK, Gottumukkala S, Tolbert WD, Richard J, Smith AB 3rd, Pazgier M, and Finzi A
- Abstract
CD4-mimetics (CD4mcs) are small molecule compounds that mimic the interaction of the CD4 receptor with HIV-1 envelope glycoproteins (Env). Env from primary viruses normally samples a "closed" conformation that occludes epitopes recognized by CD4-induced (CD4i) non-neutralizing antibodies (nnAbs). CD4mcs induce conformational changes on Env resulting in the exposure of these otherwise inaccessible epitopes. Here, we evaluated the capacity of plasma from a cohort of 50 people living with HIV to recognize HIV-1-infected cells and eliminate them by antibody-dependent cellular cytotoxicity (ADCC) in the presence of a potent indoline CD4mc. We observed a marked heterogeneity among plasma samples. By measuring the levels of different families of CD4i Abs, we found that the levels of anti-cluster A, anti-coreceptor binding site, and anti-gp41 cluster I antibodies are responsible for plasma-mediated ADCC in the presence of CD4mc., Importance: There are several reasons that make it difficult to target the HIV reservoir. One of them is the capacity of infected cells to prevent the recognition of HIV-1 envelope glycoproteins (Env) by commonly elicited antibodies in people living with HIV. Small CD4-mimetic compounds expose otherwise occluded Env epitopes, thus enabling their recognition by non-neutralizing antibodies (nnAbs). A better understanding of the contribution of these antibodies to eliminate infected cells in the presence of CD4mc could lead to the development of therapeutic cure strategies.
- Published
- 2024
- Full Text
- View/download PDF
37. The asymmetric opening of HIV-1 Env by a potent CD4 mimetic enables anti-coreceptor binding site antibodies to mediate ADCC.
- Author
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Richard J, Grunst MW, Niu L, Díaz-Salinas MA, Tolbert WD, Marchitto L, Zhou F, Bourassa C, Yang D, Chiu TJ, Chen HC, Benlarbi M, Gottumukkala S, Li W, Dionne K, Bélanger É, Chatterjee D, Medjahed H, Hendrickson WA, Sodroski J, Lang ZC, Morton AJ, Huang RK, Matthies D, Smith AB 3rd, Mothes W, Munro JB, Pazgier M, and Finzi A
- Abstract
HIV-1 envelope glycoproteins (Env) from primary HIV-1 isolates typically adopt a pretriggered "closed" conformation that resists to CD4-induced (CD4i) non-neutralizing antibodies (nnAbs) mediating antibody-dependent cellular cytotoxicity (ADCC). CD4-mimetic compounds (CD4mcs) "open-up" Env allowing binding of CD4i nnAbs, thereby sensitizing HIV-1-infected cells to ADCC. Two families of CD4i nnAbs, the anti-cluster A and anti-coreceptor binding site (CoRBS) Abs, are required to mediate ADCC in combination with the indane CD4mc BNM-III-170. Recently, new indoline CD4mcs with improved potency and breadth have been described. Here, we show that the lead indoline CD4mc, CJF-III-288, sensitizes HIV-1-infected cells to ADCC mediated by anti-CoRBS Abs alone, contributing to improved ADCC activity. Structural and conformational analyses reveal that CJF-III-288, in combination with anti-CoRBS Abs, potently stabilizes an asymmetric "open" State-3 Env conformation, This Env conformation orients the anti-CoRBS Ab to improve ADCC activity and therapeutic potential.
- Published
- 2024
- Full Text
- View/download PDF
38. NTB-A and 2B4 Natural Killer Cell Receptors Modulate the Capacity of a Cocktail of Non-Neutralizing Antibodies and a Small CD4-Mimetic to Eliminate HIV-1-Infected Cells by Antibody-Dependent Cellular Cytotoxicity.
- Author
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Marchitto L, Tauzin A, Benlarbi M, Beaudoin-Bussières G, Dionne K, Bélanger É, Chatterjee D, Bourassa C, Medjahed H, Yang D, Chiu TJ, Chen HC, Iii ABS, Richard J, and Finzi A
- Subjects
- Humans, CD4 Antigens immunology, CD4 Antigens metabolism, Human Immunodeficiency Virus Proteins immunology, Human Immunodeficiency Virus Proteins metabolism, nef Gene Products, Human Immunodeficiency Virus immunology, nef Gene Products, Human Immunodeficiency Virus metabolism, Viral Regulatory and Accessory Proteins metabolism, Viral Regulatory and Accessory Proteins immunology, Viral Regulatory and Accessory Proteins genetics, Antibodies, Neutralizing immunology, Viroporin Proteins, Antibody-Dependent Cell Cytotoxicity immunology, HIV-1 immunology, Killer Cells, Natural immunology, HIV Antibodies immunology, HIV Infections immunology, HIV Infections virology, Signaling Lymphocytic Activation Molecule Family immunology, Signaling Lymphocytic Activation Molecule Family metabolism
- Abstract
Natural Killer (NK) cells have the potential to eliminate HIV-1-infected cells by antibody-dependent cellular cytotoxicity (ADCC). NK cell activation is tightly regulated by the engagement of its inhibitory and activating receptors. The activating receptor CD16 drives ADCC upon binding to the Fc portion of antibodies; NK cell activation is further sustained by the co-engagement of activating receptors NTB-A and 2B4. During HIV-1 infection, Nef and Vpu accessory proteins contribute to ADCC escape by downregulating the ligands of NTB-A and 2B4. HIV-1 also evades ADCC by keeping its envelope glycoproteins (Env) in a "closed" conformation which effectively masks epitopes recognized by non-neutralizing antibodies (nnAbs) which are abundant in the plasma of people living with HIV. To achieve this, the virus uses its accessory proteins Nef and Vpu to downregulate the CD4 receptor, which otherwise interacts with Env and exposes the epitopes recognized by nnAbs. Small CD4-mimetic compounds (CD4mc) have the capacity to expose these epitopes, thus sensitizing infected cells to ADCC. Given the central role of NK cell co-activating receptors NTB-A and 2B4 in Fc-effector functions, we studied their contribution to CD4mc-mediated ADCC. Despite the fact that their ligands are partially downregulated by HIV-1, we found that both co-activating receptors significantly contribute to CD4mc sensitization of HIV-1-infected cells to ADCC.
- Published
- 2024
- Full Text
- View/download PDF
39. Development, optimization and ex-vivo evaluation of a transdermal formulation containing trazodone.
- Author
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Demurtas A, Nicoli S, Pescina S, Marchitto L, Ragni L, Russo V, Tommasi G, Santi P, and Padula C
- Subjects
- Animals, Swine, Skin metabolism, Skin drug effects, Permeability, Oleic Acid chemistry, Solubility, Hydrogen-Ion Concentration, Lauric Acids chemistry, Lauric Acids administration & dosage, Transdermal Patch, Chemistry, Pharmaceutical methods, Antidepressive Agents, Second-Generation administration & dosage, Antidepressive Agents, Second-Generation pharmacokinetics, Drug Delivery Systems methods, Trazodone administration & dosage, Trazodone pharmacokinetics, Administration, Cutaneous, Skin Absorption drug effects
- Abstract
Trazodone is a triazolpyridine derivative approved for the treatment of depression, and currently marketed as oral formulations. The transdermal administration of this drug could reduce side effects, related to peak plasma concentration, and improve patient adherence due to a reduced administration frequency. The aims of this work were: (a) the evaluation of the effect of pH vehicle and permeation enhancers on trazodone permeability across porcine skin ex-vivo; (b) the development and optimization of a transdermal drug delivery system containing trazodone hydrochloride. From the results obtained, it was found that the effect of pH of the vehicle on the permeation of trazodone across the skin is quite complex, because it influences both solubility and partitioning and that the presence of fatty acids in the vehicle has a notable effect on permeation (the enhancement factor obtained was approx. 100). For both the fatty acid selected (oleic and lauric) a parabolic relationship between the transdermal flux and the concentration was found, with an optimum activity in the range 2-3 %. In the second part of the work, different patches were prepared and tested ex-vivo. Overall, the results obtained seem to highlight that drug loading, rather than the components of the adhesive matrix, plays the most relevant role for the permeation of trazodone. The addition of lauric acid, which produced a considerable enhancement in solution, was not effective when included in the patch. The obtained data are promising although probably not clinically relevant for the treatment of depression, but might be interesting for the treatment of insomnia and anxiety disorder, which require much lower doses., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
40. Impact of Prolonged SARS-CoV-2 Dosing Interval in Hemodialysis Patients.
- Author
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Lamarche C, Tennankore K, Marchitto L, Beabien-Souligny W, Goupil R, Nadeau-Fredette AC, Gunaratnam L, Mac-Way F, Benlarbi M, Chatterjee D, Tom A, Medjahed H, Kaufmann DE, Finzi A, and Suri RS
- Published
- 2024
- Full Text
- View/download PDF
41. Three families of CD4-induced antibodies are associated with the capacity of plasma from people living with HIV to mediate ADCC in presence of CD4-mimetics.
- Author
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Tauzin A, Marchitto L, Bélanger É, Benlarbi M, Beaudoin-Bussières G, Prévost J, Yang D, Chiu TJ, Chen HC, Bourassa C, Medjahed H, Korzeniowski MK, Gottumukkala S, Tolbert WD, Richard J, Smith AB 3rd, Pazgier M, and Finzi A
- Abstract
CD4-mimetics (CD4mcs) are small molecule compounds that mimic the interaction of the CD4 receptor with HIV-1 envelope glycoproteins (Env). Env from primary viruses normally samples a "closed" conformation which occludes epitopes recognized by CD4-induced (CD4i) non-neutralizing antibodies (nnAbs). CD4mcs induce conformational changes on Env resulting in the exposure of these otherwise inaccessible epitopes. Here we evaluated the capacity of plasma from a cohort of 50 people living with HIV to recognize HIV-1-infected cells and eliminate them by antibody-dependent cellular cytotoxicity (ADCC) in the presence of a potent indoline CD4mc. We observed a marked heterogeneity among plasma samples. By measuring the levels of different families of CD4i Abs, we found that the levels of anti-cluster A, anti-coreceptor binding site and anti-gp41 cluster I antibodies are responsible for plasma-mediated ADCC in presence of CD4mc.
- Published
- 2024
- Full Text
- View/download PDF
42. Sustained IFN signaling is associated with delayed development of SARS-CoV-2-specific immunity.
- Author
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Brunet-Ratnasingham E, Morin S, Randolph HE, Labrecque M, Bélair J, Lima-Barbosa R, Pagliuzza A, Marchitto L, Hultström M, Niessl J, Cloutier R, Sreng Flores AM, Brassard N, Benlarbi M, Prévost J, Ding S, Anand SP, Sannier G, Marks A, Wågsäter D, Bareke E, Zeberg H, Lipcsey M, Frithiof R, Larsson A, Zhou S, Nakanishi T, Morrison D, Vezina D, Bourassa C, Gendron-Lepage G, Medjahed H, Point F, Richard J, Larochelle C, Prat A, Cunningham JL, Arbour N, Durand M, Richards JB, Moon K, Chomont N, Finzi A, Tétreault M, Barreiro L, Wolf G, and Kaufmann DE
- Subjects
- Humans, Female, Male, Middle Aged, Immunoglobulin G blood, Immunoglobulin G immunology, CD4-Positive T-Lymphocytes immunology, Aged, Adult, Spike Glycoprotein, Coronavirus immunology, Spike Glycoprotein, Coronavirus metabolism, Spike Glycoprotein, Coronavirus genetics, COVID-19 immunology, SARS-CoV-2 immunology, Antibodies, Viral immunology, Antibodies, Viral blood, Signal Transduction immunology, Interferons metabolism, Interferons immunology
- Abstract
Plasma RNAemia, delayed antibody responses and inflammation predict COVID-19 outcomes, but the mechanisms underlying these immunovirological patterns are poorly understood. We profile 782 longitudinal plasma samples from 318 hospitalized patients with COVID-19. Integrated analysis using k-means reveals four patient clusters in a discovery cohort: mechanically ventilated critically-ill cases are subdivided into good prognosis and high-fatality clusters (reproduced in a validation cohort), while non-critical survivors segregate into high and low early antibody responders. Only the high-fatality cluster is enriched for transcriptomic signatures associated with COVID-19 severity, and each cluster has distinct RBD-specific antibody elicitation kinetics. Both critical and non-critical clusters with delayed antibody responses exhibit sustained IFN signatures, which negatively correlate with contemporaneous RBD-specific IgG levels and absolute SARS-CoV-2-specific B and CD4
+ T cell frequencies. These data suggest that the "Interferon paradox" previously described in murine LCMV models is operative in COVID-19, with excessive IFN signaling delaying development of adaptive virus-specific immunity., (© 2024. The Author(s).)- Published
- 2024
- Full Text
- View/download PDF
43. Gaining Biological Insights through Supervised Data Visualization.
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Rhodes JS, Aumon A, Morin S, Girard M, Larochelle C, Brunet-Ratnasingham E, Pagliuzza A, Marchitto L, Zhang W, Cutler A, Grand'Maison F, Zhou A, Finzi A, Chomont N, Kaufmann DE, Zandee S, Prat A, Wolf G, and Moon KR
- Abstract
Dimensionality reduction-based data visualization is pivotal in comprehending complex biological data. The most common methods, such as PHATE, t-SNE, and UMAP, are unsupervised and therefore reflect the dominant structure in the data, which may be independent of expert-provided labels. Here we introduce a supervised data visualization method called RF-PHATE, which integrates expert knowledge for further exploration of the data. RF-PHATE leverages random forests to capture intricate featurelabel relationships. Extracting information from the forest, RF-PHATE generates low-dimensional visualizations that highlight relevant data relationships while disregarding extraneous features. This approach scales to large datasets and applies to classification and regression. We illustrate RF-PHATE's prowess through three case studies. In a multiple sclerosis study using longitudinal clinical and imaging data, RF-PHATE unveils a sub-group of patients with non-benign relapsingremitting Multiple Sclerosis, demonstrating its aptitude for time-series data. In the context of Raman spectral data, RF-PHATE effectively showcases the impact of antioxidants on diesel exhaust-exposed lung cells, highlighting its proficiency in noisy environments. Furthermore, RF-PHATE aligns established geometric structures with COVID-19 patient outcomes, enriching interpretability in a hierarchical manner. RF-PHATE bridges expert insights and visualizations, promising knowledge generation. Its adaptability, scalability, and noise tolerance underscore its potential for widespread adoption.
- Published
- 2024
- Full Text
- View/download PDF
44. NOX2 deficiency enhances priming and activation of the NLRP3 inflammasome.
- Author
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Monjarret B, Shour S, Benyoucef A, Heckel E, Marchitto L, Leiding JW, Cros G, Fernandez I, Joyal JS, and Touzot F
- Abstract
Background: Nicotinamide adenine dinucleotide phosphate oxidase complex 2 (NOX2) deficiency, or chronic granulomatous disease (CGD), is an inborn error of immunity associated with increased susceptibility to infection and inflammatory manifestations. The pathophysiologic mechanism leading to the increased inflammatory response in CGD remains elusive., Objective: We investigated the pathophysiologic mechanisms leading to NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in NOX2 deficiency., Methods: We used NOX2-deficient human primary and CRISPR-engineered macrophages to show that NOX2 deficiency enhances the inflammatory response mainly by modulating the 2 steps of NLRP3 inflammasome activation: its transcriptional priming and its posttranslational triggering., Results: At the transcriptional level, NOX2-deficient phagocytes display increased priming of the NLRP3 inflammasome, as evidenced by increased transcription of NLRP3 and IL-1β through an IL-1β-dependent stimulation of the nuclear factor kappa-light-chain enhancer of activated B cells (aka NF-κB) pathway. At the posttranslational level, the absence of NOX2 triggers the NLRP3 inflammasome activation by increased K
+ efflux and excessive release of mitochondrial DNA due to mitochondrial damage. Furthermore, NLRP3-driven pyroptosis in NOX2-deficient phagocytes further enhances NLRP3 activation by increasing K+ efflux., Conclusion: Our results unveil the role of NOX2 as a repressor of the inflammatory response at both transcriptional and posttranslational levels and pave the way for a more targeted approach to treating CGD patients with inflammatory manifestations., (Copyright © 2023 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
45. Humoral Responses Elicited by SARS-CoV-2 mRNA Vaccine in People Living with HIV.
- Author
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Marchitto L, Chatterjee D, Ding S, Gendron-Lepage G, Tauzin A, Boutin M, Benlarbi M, Medjahed H, Sylla M, Lanctôt H, Durand M, Finzi A, and Tremblay C
- Subjects
- Humans, COVID-19 Vaccines, SARS-CoV-2, Longitudinal Studies, Antibodies, RNA, Messenger genetics, Vaccination, Antibodies, Viral, Antibodies, Neutralizing, Immunity, Humoral, mRNA Vaccines, COVID-19 prevention & control, HIV Infections
- Abstract
While mRNA SARS-CoV-2 vaccination elicits strong humoral responses in the general population, humoral responses in people living with HIV (PLWH) remain to be clarified. Here, we conducted a longitudinal study of vaccine immunogenicity elicited after two and three doses of mRNA SARS-CoV-2 vaccine in PLWH stratified by their CD4 count. We measured the capacity of the antibodies elicited by vaccination to bind the Spike glycoprotein of different variants of concern (VOCs). We also evaluated the Fc-mediated effector functions of these antibodies by measuring their ability to eliminate CEM.NKr cells stably expressing SARS-CoV-2 Spikes. Finally, we measured the relative capacity of the antibodies to neutralize authentic SARS-CoV-2 virus after the third dose of mRNA vaccine. We found that after two doses of SARS-CoV-2 mRNA vaccine, PLWH with a CD4 count < 250/mm
3 had lower levels of anti-RBD IgG antibodies compared to PLWH with a CD4 count > 250/mm3 ( p < 0.05). A third dose increased these levels and importantly, no major differences were observed in their capacity to mediate Fc-effector functions and neutralize authentic SARS-CoV-2. Overall, our work demonstrates the importance of mRNA vaccine boosting in immuno-compromised individuals presenting low levels of CD4.- Published
- 2023
- Full Text
- View/download PDF
46. Impact of HIV-1 Vpu-mediated downregulation of CD48 on NK-cell-mediated antibody-dependent cellular cytotoxicity.
- Author
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Marchitto L, Benlarbi M, Prévost J, Laumaea A, Descôteaux-Dinelle J, Medjahed H, Bourassa C, Gendron-Lepage G, Kirchhoff F, Sauter D, Hahn BH, Finzi A, and Richard J
- Subjects
- Humans, Down-Regulation, Ligands, Antibody-Dependent Cell Cytotoxicity, Killer Cells, Natural, Signaling Lymphocytic Activation Molecule Family genetics, HIV-1 genetics, HIV Infections
- Abstract
HIV-1 evades antibody-dependent cellular cytotoxicity (ADCC) responses not only by controlling Env conformation and quantity at the cell surface but also by altering NK cell activation via the downmodulation of several ligands of activating and co-activating NK cell receptors. The signaling lymphocyte activation molecule (SLAM) family of receptors, which includes NTB-A and 2B4, act as co-activating receptors to sustain NK cell activation and cytotoxic responses. These receptors cooperate with CD16 (FcγRIII) and other activating receptors to trigger NK cell effector functions. In that context, Vpu-mediated downregulation of NTB-A on HIV-1-infected CD4 T cells was shown to prevent NK cell degranulation via an homophilic interaction, thus contributing to ADCC evasion. However, less is known on the capacity of HIV-1 to evade 2B4-mediated NK cell activation and ADCC. Here, we show that HIV-1 downregulates the ligand of 2B4, CD48, from the surface of infected cells in a Vpu-dependent manner. This activity is conserved among Vpu proteins from the HIV-1/SIVcpz lineage and depends on conserved residues located in its transmembrane domain and dual phosphoserine motif. We show that NTB-A and 2B4 stimulate CD16-mediated NK cell degranulation and contribute to ADCC responses directed to HIV-1-infected cells to the same extent. Our results suggest that HIV-1 has evolved to downmodulate the ligands of both SLAM receptors to evade ADCC. IMPORTANCE Antibody-dependent cellular cytotoxicity (ADCC) can contribute to the elimination of HIV-1-infected cells and HIV-1 reservoirs. An in-depth understanding of the mechanisms used by HIV-1 to evade ADCC might help develop novel approaches to reduce the viral reservoirs. Members of the signaling lymphocyte activation molecule (SLAM) family of receptors, such as NTB-A and 2B4, play a key role in stimulating NK cell effector functions, including ADCC. Here, we show that Vpu downmodulates CD48, the ligand of 2B4, and this contributes to protect HIV-1-infected cells from ADCC. Our results highlight the importance of the virus to prevent the triggering of the SLAM receptors to evade ADCC., Competing Interests: The authors declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
47. Piperidine CD4-Mimetic Compounds Expose Vulnerable Env Epitopes Sensitizing HIV-1-Infected Cells to ADCC.
- Author
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Ding S, Tolbert WD, Zhu H, Lee D, Marchitto L, Higgins T, Zhao X, Nguyen D, Sherburn R, Richard J, Gendron-Lepage G, Medjahed H, Mohammadi M, Abrams C, Pazgier M, Smith AB 3rd, and Finzi A
- Subjects
- Humans, Epitopes, CD4-Positive T-Lymphocytes, CD4 Antigens metabolism, Antibody-Dependent Cell Cytotoxicity, HIV Envelope Protein gp120 metabolism, HIV Antibodies, HIV-1, HIV Seropositivity, HIV Infections
- Abstract
The ability of the HIV-1 accessory proteins Nef and Vpu to decrease CD4 levels contributes to the protection of infected cells from antibody-dependent cellular cytotoxicity (ADCC) by preventing the exposure of Env vulnerable epitopes. Small-molecule CD4 mimetics (CD4mc) based on the indane and piperidine scaffolds such as (+)-BNM-III-170 and ( S )-MCG-IV-210 sensitize HIV-1-infected cells to ADCC by exposing CD4-induced (CD4i) epitopes recognized by non-neutralizing antibodies that are abundantly present in plasma from people living with HIV. Here, we characterize a new family of CD4mc, ( S )-MCG-IV-210 derivatives, based on the piperidine scaffold which engages the gp120 within the Phe43 cavity by targeting the highly conserved Asp
368 Env residue. We utilized structure-based approaches and developed a series of piperidine analogs with improved activity to inhibit the infection of difficult-to-neutralize tier-2 viruses and sensitize infected cells to ADCC mediated by HIV+ plasma. Moreover, the new analogs formed an H-bond with the α-carboxylic acid group of Asp368 , opening a new avenue to enlarge the breadth of this family of anti-Env small molecules. Overall, the new structural and biological attributes of these molecules make them good candidates for strategies aimed at the elimination of HIV-1-infected cells.- Published
- 2023
- Full Text
- View/download PDF
48. Reconstruction of a polyclonal ADCC antibody repertoire from an HIV-1 non-transmitting mother.
- Author
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Yaffe ZA, Ding S, Sung K, Chohan V, Marchitto L, Doepker L, Ralph D, Nduati R, Matsen FA 4th, Finzi A, and Overbaugh J
- Abstract
Human natural history and vaccine studies support a protective role of antibody dependent cellular cytotoxicity (ADCC) activity against many infectious diseases. One setting where this has consistently been observed is in HIV-1 vertical transmission, where passively acquired ADCC activity in HIV-exposed infants has correlated with reduced acquisition risk and reduced pathogenesis in HIV+ infants. However, the characteristics of HIV-specific antibodies comprising a maternal plasma ADCC response are not well understood. Here, we reconstructed monoclonal antibodies (mAbs) from memory B cells from late pregnancy in mother MG540, who did not transmit HIV to her infant despite several high-risk factors. Twenty mAbs representing 14 clonal families were reconstructed, which mediated ADCC and recognized multiple HIV Envelope epitopes. In experiments using Fc-defective variants, only combinations of several mAbs accounted for the majority of plasma ADCC of MG540 and her infant. We present these mAbs as evidence of a polyclonal repertoire with potent HIV-directed ADCC activity., Competing Interests: The authors declare no competing interests., (© 2023 The Authors.)
- Published
- 2023
- Full Text
- View/download PDF
49. A third SARS-CoV-2 mRNA vaccine dose in people receiving hemodialysis overcomes B cell defects but elicits a skewed CD4 + T cell profile.
- Author
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Sannier G, Nicolas A, Dubé M, Marchitto L, Nayrac M, Tastet O, Chatterjee D, Tauzin A, Lima-Barbosa R, Laporte M, Cloutier R, Sreng Flores AM, Boutin M, Gong SY, Benlarbi M, Ding S, Bourassa C, Gendron-Lepage G, Medjahed H, Goyette G, Brassard N, Delgado GG, Niessl J, Gokool L, Morrisseau C, Arlotto P, Rios N, Tremblay C, Martel-Laferrière V, Prat A, Bélair J, Beaubien-Souligny W, Goupil R, Nadeau-Fredette AC, Lamarche C, Finzi A, Suri RS, and Kaufmann DE
- Subjects
- Humans, SARS-CoV-2 genetics, CD4-Positive T-Lymphocytes, mRNA Vaccines, COVID-19 Vaccines, COVID-19 prevention & control
- Abstract
Cellular immune defects associated with suboptimal responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination in people receiving hemodialysis (HD) are poorly understood. We longitudinally analyze antibody, B cell, CD4
+ , and CD8+ T cell vaccine responses in 27 HD patients and 26 low-risk control individuals (CIs). The first two doses elicit weaker B cell and CD8+ T cell responses in HD than in CI, while CD4+ T cell responses are quantitatively similar. In HD, a third dose robustly boosts B cell responses, leads to convergent CD8+ T cell responses, and enhances comparatively more T helper (TH ) immunity. Unsupervised clustering of single-cell features reveals phenotypic and functional shifts over time and between cohorts. The third dose attenuates some features of TH cells in HD (tumor necrosis factor alpha [TNFα]/interleukin [IL]-2 skewing), while others (CCR6, CXCR6, programmed cell death protein 1 [PD-1], and HLA-DR overexpression) persist. Therefore, a third vaccine dose is critical to achieving robust multifaceted immunity in hemodialysis patients, although some distinct TH characteristics endure., Competing Interests: Declaration of interests C.T. serves as a consultant for Merck, Gilead, GSK, AstraZeneca, and Medicago., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
50. Preparation and Characterization of Amorphous Solid Dispersions for the Solubilization of Fenretinide.
- Author
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Zuccari G, Russo E, Villa C, Zorzoli A, Marimpietri D, Marchitto L, and Alfei S
- Abstract
Fenretinide (4-HPR), a retinoid derivative, has shown high antitumor activity, a low toxicological profile, and no induction of resistance. Despite these favorable features, the variability in oral absorption due to its low solubility combined with the high hepatic first pass effect strongly reduce clinical outcomes. To overcome the solubility and dissolution challenges of poorly water-soluble 4-HPR, we prepared a solid dispersion of the drug (4-HPR-P5) using a hydrophilic copolymer (P5) previously synthesized by our team as the solubilizing agent. The molecularly dispersed drug was obtained by antisolvent co-precipitation, an easy and up-scalable technique. A higher drug apparent solubility (1134-fold increase) and a markedly faster dissolution were obtained. In water, the colloidal dispersion showed a mean hydrodynamic diameter of 249 nm and positive zeta potential (+41.3 mV), confirming the suitability of the formulation for intravenous administration. The solid nanoparticles were also characterized by a high drug payload (37%), as was also evidenced by a chemometric-assisted Fourier transform infrared spectroscopy (FTIR) investigation. The 4-HPR-P5 exhibited antiproliferative activity, with IC50 values of 1.25 and 1.93 µM on IMR-32 and SH-SY5Y neuroblastoma cells, respectively. Our data confirmed that the 4-HPR-P5 formulation developed herein was able to increase drug apparent aqueous solubility and provide an extended release over time, thus suggesting that it represents an efficient approach to improve 4-HPR bioavailability., Competing Interests: The authors declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
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