Machine learning and reduced order modelling for the simulation of braided stent deployment

Endoluminal reconstruction using flow diverters represents a novel paradigm for the minimally invasive treatment of intracranial aneurysms. The configuration assumed by these very dense braided stents once deployed within the parent vessel is not easily predictable and medical volumetric images alone may be insufficient to plan the treatment satisfactorily. Therefore, here we propose a fast and accurate machine learning and reduced order modelling framework, based on finite element simulations, to assist practitioners in the planning and interventional stages. It consists of a first classification step to determine a priori whether a simulation will be successful (good conformity between stent and vessel) or not from a clinical perspective, followed by a regression step that provides an approximated solution of the deployed stent configuration. The latter is achieved using a non-intrusive reduced order modelling scheme that combines the proper orthogonal decomposition algorithm and Gaussian process regression. The workflow was validated on an idealized intracranial artery with a saccular aneurysm and the effect of six geometrical and surgical parameters on the outcome of stent deployment was studied. We trained six machine learning models on a dataset of varying size and obtained classifiers with up to 95% accuracy in predicting the deployment outcome. The support vector machine model outperformed the others when considering a small dataset of 50 training cases, with an accuracy of 93% and a specificity of 97%. On the other hand, real-time predictions of the stent deployed configuration were achieved with an average validation error between predicted and high-fidelity results never greater than the spatial resolution of 3D rotational angiography, the imaging technique with the best spatial resolution (0.15 mm). Such accurate predictions can be reached even with a small database of 47 simulations: by increasing the training simulations to 147, the average prediction error is reduced to 0.07 mm. These results are promising as they demonstrate the ability of these techniques to achieve simulations within a few milliseconds while retaining the mechanical realism and predictability of the stent deployed configuration

Machine learning and reduced order modelling for the simulation of braided stent deployment

Endoluminal reconstruction using flow diverters represents a novel paradigm for the minimally invasive treatment of intracranial aneurysms. The configuration assumed by these very dense braided stents once deployed within the parent vessel is not easily predictable and medical volumetric images alone may be insufficient to plan the treatment satisfactorily. Therefore, here we propose a fast and accurate machine learning and reduced order modelling framework, based on finite element simulations, to assist practitioners in the planning and interventional stages. It consists of a first classification step to determine a priori whether a simulation will be successful (good conformity between stent and vessel) or not from a clinical perspective, followed by a regression step that provides an approximated solution of the deployed stent configuration. The latter is achieved using a non-intrusive reduced order modelling scheme that combines the proper orthogonal decomposition algorithm and Gaussian process regression. The workflow was validated on an idealised intracranial artery with a saccular aneurysm and the effect of six geometrical and surgical parameters on the outcome of stent deployment was studied. The two-step workflow allows the classification of deployment conditions with up to 95% accuracy and real-time prediction of the stent deployed configuration with an average prediction error never greater than the spatial resolution of 3D rotational angiography (0.15 mm). These results are promising as they demonstrate the ability of these techniques to achieve simulations within a few milliseconds while retaining the mechanical realism and predictability of the stent deployed configuration

Setting of Methods for Analysis of Mucosal Antibodies in Seminal and Vaginal Fluids of HIV Seropositive Subjects from Cambodian and Italian Cohorts

International audienceBACKGROUND: Genital mucosae play a key role in protection from STD and HIV infection, due to their involvement in both horizontal and vertical disease transmission. High variability of published observations concerning IgA isolation and quantification underlies the strong requirement of specific methods able to maximize investigation on HIV-specific IgA. METHODOLOGY: Genital fluids from 109 subjects, including male and female cohorts from Italy and Cambodia, were collected, aliquoted and processed with different techniques, to assess optimal conditions maximizing mucosal antibody recovery. Three sampling techniques, up to sixteen preservation conditions, six ELISA methods and four purifications protocols were compared. PRINCIPAL FINDINGS: The optimal method here described took advantage of Weck-Cel sampling of female mucosal fluids. Immediate processing of genital fluids, with the addition of antibiotics and EDTA, improved recovery of vaginal IgA, while the triple addition of EDTA, antibiotics and protease inhibitors provided the highest amount of seminal IgA. Due to low amount of IgA in mucosal fluids, a high sensitive sandwich ELISA assay was set; sensitivity was enhanced by milk-based overcoating buffer and by a two-step biotin-streptavidin signal amplification. Indeed, commercial antisera to detect human immunoglobulins showed weak cross-reactivity to different antibody types. Three-step affinity purification provided reproducible immunoglobulin recovery from genital specimens, while conventional immuno-affinity IgA purification was found poorly manageable. Affinity columns were suitable to isolate mucosal IgA, which are ten-fold less concentrated than IgG in genital specimens, and provided effective separation of IgA monomers, dimers, and J-chains. Jacalin-bound resin successfully separated IgA1 from IgA2 subfraction. CONCLUSIONS/SIGNIFICANCE: Specific, effective and reliable methods to study local immunity are key items in understanding host mucosal response. The sequence of methods here described is effective and reliable in analysing humoral local responses, and may provide a solid advance to identify and measure the effective mucosal responses to HIV

Study of the impacts of droplets deposited from the gas core onto a gas-sheared liquid film

The results of an experimental study on droplet impactions in the flow of a gas-sheared liquid film are presented. In contrast to most similar studies, the impacting droplets were entrained from film surface by the gas stream. The measurements provide film thickness data, resolved in both longitudinal and transverse coordinates and in time together with the images of droplets above the interface and images of gas bubbles entrapped by liquid film. The parameters of impacting droplets were measured together with the local liquid film thickness. Two main scenarios of droplet-film interaction, based on type of film perturbation, are identified; the parameter identifying which scenario occurs is identified as the angle of impingement. At large angles an asymmetric crater appears on film surface; at shallow angles a long, narrow furrow appears. The most significant difference between the two scenarios is related to possible impact outcome: craters may lead to creation secondary droplets, whereas furrows are accompanied by entrapment of gas bubbles into the liquid film. In addition, occurrence of partial survival of impacting droplet is reported

Longitudinal Tracking of Human Fetal Cells Labeled with Super Paramagnetic Iron Oxide Nanoparticles in the Brain of Mice with Motor Neuron Disease

Stem Cell (SC) therapy is one of the most promising approaches for the treatment of Amyotrophic Lateral Sclerosis (ALS). Here we employed Super Paramagnetic Iron Oxide nanoparticles (SPIOn) and Hoechst 33258 to track human Amniotic Fluid Cells (hAFCs) after transplantation in the lateral ventricles of wobbler (a murine model of ALS) and healthy mice. By in vitro, in vivo and ex vivo approaches we found that: 1) the main physical parameters of SPIOn were maintained over time; 2) hAFCs efficiently internalized SPIOn into the cytoplasm while Hoechst 33258 labeled nuclei; 3) SPIOn internalization did not alter survival, cell cycle, proliferation, metabolism and phenotype of hAFCs; 4) after transplantation hAFCs rapidly spread to the whole ventricular system, but did not migrate into the brain parenchyma; 5) hAFCs survived for a long time in the ventricles of both wobbler and healthy mice; 6) the transplantation of double-labeled hAFCs did not influence mice survival

Fabrication of Compliant and Transparent Hollow Cerebral Vascular Phantoms for In Vitro Studies Using 3D Printing and Spin–Dip Coating

Endovascular surgery through flow diverters and coils is increasingly used for the minimally invasive treatment of intracranial aneurysms. To study the effectiveness of these devices, in vitro tests are performed in which synthetic vascular phantoms are typically used to reproduce in vivo conditions. In this paper, we propose a manufacturing process to obtain compliant and transparent hollow vessel replicas to assess the mechanical behaviour of endovascular devices and perform flow measurements. The vessel models were obtained in three main steps. First, a mould was 3D-printed in a water-soluble material; two techniques, fusion deposition modelling and stereolithography, were compared for this purpose. Then, the mould was covered with a thin layer of silicone through spin–dip coating, and finally, when the silicone layer solidified, it was dissolved in a hot water bath. The final models were tested in terms of the quality of the final results, the mechanical properties of the silicone, thickness uniformity, and transparency properties. The proposed approach makes it possible to produce models of different sizes and complexity whose transparency and mechanical properties are suitable for in vitro experiments. Its applicability is demonstrated through idealised and patient-specific cases

Single and double drop impacts onto deep and thick liquid layers

The crater formed by the impact of a drop onto a deep pool has been characterized for several impact parameters. A new theoretical model for its evolution has been formulated. Potential flow theory has been used to model the flow around the crater as the velocity field given by a moving expanding sphere, whose equations of motion have been obtained through a balance of stresses at the crater interface and include the effects of inertia, gravity, surface tension and viscosity. Agreement with experimental data from the present study and from literature is rather good. A map of the predicted values of the maximum crater depth as a function of the impact parameters has been produced.The influence of a finite value of the depth of the target liquid layer has been investigated in comparison with single drop impacts onto a deep pool, with particular attention on the crater evolution. The presence of the wall has been observed to reduce the velocity of penetration of the crater, but to do not significatively change its maximum depth, which is only reached later. For this reason the maximum crater depth of a deep pool impact has been chosen as reference parameter for the usual classification in thin films, thick films and deep pools of the depth of the target liquid layers in relation with the parameters of the impacting drop. This choice has a more physical significance, since it accounts for the kinetic energy of the impacting drop instead of only its diameter.A phenomenological investigation of double drop impacts onto a deep pool has been for the first time performed. The phenomena arising have been observed to be characterized by several interactions, which have been described and discussed. The two craters and the two jets ejected from the craters may merge each other. New complex hollow shapes of the crater or of the jet resulting from the merging may be produced and a new mechanism of bubble entrapment has been detected. A test case for the validation of numerical codes has also been proposed, since the simultaneous impact of two identical drops represents a new example of three dimensional free surface flow, instead of the axial symmetry typical of a single drop impact.Single drop impacts onto a deep pool have been studied in relation with the extensive existing literature. A new classification of the flow regimes has been suggested and a new “trampoline” regime has been detected and described. The phenomenon of the closure of the crown above the crater, typical of terminal speed impacts, has been obtained with unprecedented low impact parameters and it has been observed to be promoted by the sphericity of the impacting drop, while it does not take place if the drop is oblate.A test rig for the high-speed-visualization of interface phenomena has been built and experimental investigations using highspeed- imaging and image processing have been performed.The present experimental and analytical study deals with single and double drop impacts onto a deep pool or liquid layers of finite thickness, with a general purpose of understanding the complex flows generated by spray impacts. The study is focused mainly on the observation of the evolution of the crater formed by the drop impacts and the description of the associated flow in the liquid layer

Progetto BRASSICA: Valutazione del ruolo dei vegetali delle Brassicaceae nel controllo dei disturbi della menopausa iatrogena indotta dai trattamenti ormonali in donne operate di tumore al seno

Il Progetto BRASSICA nasce con l’obiettivo di studiare gli effetti dell’assunzione dei vegetali della famiglia delle Brassicaceae sui sintomi del climaterio, in particolare sui sintomi vasomotori, nelle pazienti con storia di cancro al seno in terapia antiestrogenica. Le terapie adiuvanti per il carcinoma mammario, infatti, possono causare nelle pazienti l’instaurarsi di una condizione di insufficienza ovarica precoce chiamata menopausa iatrogena. La sintomatologia associata a tale condizione è multiforme e peggiora la qualità della vita delle pazienti. La terapia ormonale sostitutiva è sconsigliata per coloro che hanno una storia di cancro al seno, e, sebbene l’efficacia di altri farmaci sia stata valutata, il loro utilizzo comporta anche una serie di effetti collaterali che possono renderne difficile l’assunzione. Per questo motivo, le donne in menopausa iatrogena spesso ricorrono a terapie non convenzionali o all’assunzione di nutraceutici in grado di alleviare i sintomi dominanti. In tal senso, numerose evidenze mostrano l’efficacia dei vegetali della famiglia delle Brassicaceae nell’alleviare la sintomatologia del climaterio e nella prevenzione delle comorbidità connesse alla menopausa, quali rischio cardiovascolare e i disturbi ossei. Inoltre la presenza di sostanze (glucosinolati) con nota attività antitumorale rafforza la convinzione che potrebbero essere utili anche nella prevenzione di recidive