Modelli della sensibilità allo strain-rate e identificazione dei parametri caratteristici di lamiere di acciaio

È ormai ampiamente riconosciuto che i materiali hanno un comportamento che varia con la velocità di deformazione. L'influenza della velocità sulle proprietà del materiale viene modellata tramite modelli costitutivi. I modelli che sono stati proposti sono numerosi e differenti fra di loro e non esistono dei criteri ben definiti per la loro scelta. I dati caratteristici dei vari materiali non sempre sono disponibili anche perché la loro identificazione è piuttosto difficoltosa. Scopo del lavoro è di implementare una procedura numerica per l'identificazione dei parametri di influenza rispetto alla velocità di deformazione, tramite la simulazione di una prova sperimentale. Per questo scopo sono stati considerati e confrontati diversi modelli. Di questi modelli si sono messi in evidenza i vantaggi e le principali limitazioni e si sono potuti determinare i parametri per i due materiali considerat

Mr-Nom: Multi-Scale Resolution of Neuronal Cells in Nissl-Stained Histological Slices Via Deliberate over-Segmentation and Merging

In comparative neuroanatomy, the characterization of brain cytoarchitecture is critical to a better understanding of brain structure and function, as it helps to distill information on the development, evolution, and distinctive features of different populations. The automatic segmentation of individual brain cells is a primary prerequisite and yet remains challenging. A new method (MR-NOM) was developed for the instance segmentation of cells in Nissl-stained histological images of the brain. MR-NOM exploits a multi-scale approach to deliberately over-segment the cells into superpixels and subsequently merge them via a classifier based on shape, structure, and intensity features. The method was tested on images of the cerebral cortex, proving successful in dealing with cells of varying characteristics that partially touch or overlap, showing better performance than two state-of-the-art methods

Posttransplant lymphoproliferative disorders in neuronal xenotransplanted macaques

Posttransplant lymphoproliferative disorders (PTLDs) are a heterogeneous group of lymphoid proliferations that occur in the setting of depressed T-cell function due to immunosuppressive therapy used following solid organ transplantation, hematopoietic stem cell transplantation, and also xenotransplantation. In the present study, 28 immunosuppressed parkinsonian Macaca fascicularis were intracerebrally injected with wild-type or CTLA4-Ig transgenic porcine xenografts to identify a suitable strategy to enable long-term cell survival, maturation, and differentiation. Nine of 28 (32%) immunosuppressed primates developed masses compatible with PTLD, located mainly in the gastrointestinal tract and/or nasal cavity. The masses were classified as monomorphic PTLD according to the World Health Organization classification. Immunohistochemistry and polymerase chain reaction (PCR) analyses revealed that the PTLDs were associated with macaca lymphocryptovirus as confirmed by double-labeling immunohistochemistry for CD20 and Epstein-Barr nuclear antigen 2 (EBNA-2), where the viral protein was located within the CD20+ neoplastic B cells. In sera from 3 distinct phases of the experimental life of the primates, testing by quantitative PCR revealed a progression of the viral load that paralleled the PTLD progression and no evidence of zoonotic transmission of porcine lymphotropic herpesvirus through xenoneuronal grafts. These data suggest that monitoring the variation of macaca lymphocryptovirus DNA in primates could be used as a possible early diagnostic tool for PTLD progression, allowing preemptive treatment such as immunosuppression therapy reduction

Sul collasso assiale di travi in parete sottile realizzate con adesivi : primi risultati sperimentali

Le giunzioni incollate possono rappresentare una valida alternativa ad altri tipi di giunzioni più tradizionali, come la saldatura a punti o la rivettatura. L’uso di tali giunzioni nel settore autoveicolistico, però, è stato sinora limitato a particolari strutturali di secondaria importanza, tra le altre ragioni anche a causa della scarsità di prove sperimentali che determinino l’effettiva capacità di resistenza in condizioni normali di utilizzo e di assorbimento energetico in caso di urto di strutture realizzate per incollaggio. In questo lavoro si confrontano le prestazioni strutturali di uno stesso elemento tipico dei telai automobilistici, realizzato con due diverse tecnologie di assemblaggio: saldatura a punti oppure incollaggio, inoltre per l’incollaggio sono stati considerati un adesivo acrilico ed uno epossidico. Le prove sperimentali svolte hanno determinato l’efficacia della giunzione incollata dal punto di vista dell’assorbimento energetico in caso di sollecitazione assiale quasi-statica, per confronto con l’analoga caratteristica di assorbimento della trave saldata a punti, in particolare con l’adesivo acrilico si è avuto un significativo aumento della forza media (+45%) e della forza massima iniziale (+52%)

A Pig Model of Hemivascular Liver Occlusion for The Study of Ischemia-Reperfusion Injury: Use of an Infrared System for Detecting Ischemic Areas

Aim: Different animals are used as experimental models for the hepatic Ischemia- Reperfusion (IR) injury investigations and for each one of these animal models, many different surgical approaches have been performed. The aim of our study was to establish a new surgical pig model in which a hemi-liver is used to study the pathophysiology of hepatic IR injury. Contro-lateral hemi- liver is used as an internal control in the same animal. Methods: Liver ischemia was performed in six pigs by clamping the hepatic artery and vein and the portal vein to isolate the left hepatic lobe. Four hours of warm ischemia were followed by 4-hourrs of reperfusion. Biochemical and hematological analyses were performed throughout the experiments. Needle biopsies were obtained prior to ischemia and then hourly during the reperfusion for evaluation of tissue damage. To assess local temperature gradients on the liver surface a focal plane array detector camera was used. Results: Four hours ischemia induced mild signs of hepatic damage on the left ischemic lobe while more dramatic changes were evidenced after 2-hours reperfusion. Absence of tissue damage was detected on the right lobe. The liver functional test reached their maximum value at 2-4 hours after reperfusion. Conclusion: Our model is easy to perform, feasible and reproducible. This surgical model minimizes biases dependent on the individual response of different animals under the same conditions. In this IR model the new technology of an infrared thermocamera was used to control temperature changes and provide clinically important real-time information during surgery

MHC matching fails to prevent long-term rejection of iPSC-derived neurons in non-human primates

open12siopenAron Badin R.; Bugi A.; Williams S.; Vadori M.; Michael M.; Jan C.; Nassi A.; Lecourtois S.; Blancher A.; Cozzi E.; Hantraye P.; Perrier A.L.Aron Badin, R.; Bugi, A.; Williams, S.; Vadori, M.; Michael, M.; Jan, C.; Nassi, A.; Lecourtois, S.; Blancher, A.; Cozzi, E.; Hantraye, P.; Perrier, A. L

The immunological barriers to xenotransplantation

The availability of cells, tissues and organs from a non-human species such as the pig could, at least in theory, meet the demand of organs necessary for clinical transplantation. At this stage, the important goal of getting over the first year of survival has been reported for both cellular and solid organ xenotransplantation in relevant preclinical primate models. In addition, xenotransplantation is already in the clinic as shown by the broad use of animal-derived medical devices, such as bioprosthetic heart valves and biological materials used for surgical tissue repair. At this stage, however, prior to starting a wide-scale clinical application of xenotransplantation of viable cells and organs, the important obstacle represented by the humoral immune response will need to be overcome. Likewise, the barriers posed by the activation of the innate immune system and coagulative pathway will have to be controlled. As far as xenogeneic nonviable xenografts, increasing evidence suggests that considerable immune reactions, mediated by both innate and adaptive immunity, take place and influence the long-term outcome of xenogeneic materials in patients, possibly precluding the use of bioprosthetic heart valves in young individuals. In this context, the present article provides an overview of current knowledge on the immune processes following xenotransplantation and on the possible therapeutic interventions to overcome the immunological drawbacks involved in xenotransplantation

Immunological challenges and therapies in xenotransplantation

Xenotransplantation, or the transplantation of cells, tissues, or organs between different species, was proposed a long time ago as a possible solution to the worldwide shortage of human organs and tissues for transplantation. In this setting, the pig is currently seen as the most likely candidate species. In the last decade, progress in this field has been remarkable and includes a better insight into the immunological mechanisms underlying the rejection process. Several immunological hurdles nonetheless remain, such as the strong antibodymediated and innate or adaptive cellular immune responses linked to coagulation derangements, precluding indefinite xenograft survival. This article reviews our current understanding of the immunological mechanisms involved in xenograft rejection and the potential strategies that may enable xenotransplantation to become a clinical reality in the not-toodistant future. \ua9 2014 Cold Spring Harbor Laboratory Press; all rights reserved