Effetti dell'acido urico sulle cellule glomerulari mesangiali: meccanismi intracellulari di trasduzione del segnale e possibili implicazioni nella progressione del danno renale e nella sindrome infiammatoria in corso di nefropatie croniche

Uric acid is a major inducer of inflammation in renal interstitium and may play a role in the progression of renal damage in hyperuricemic subjects with primary nephropathies, renal vascular disease, and essential hypertension. At the same time, UA also acts as a water-soluble scavenger of reactive oxygen species. We evaluated the cellular effects of UA on cultured HMC as a potential interstitial target for abnormally elevated levels in acute and chronic renal disease. Intracellular free Ca2+ ([Ca2+]i) was monitored by microfluorometry of fura 2-loaded cells, while oxidation of intracellularly trapped non-fluorescent 2’,7’-dichlorofluorescein diacetate (DCFHDA, 20 uM) was employed to assess the generation of reactive oxygen species during 12-hr incubations with various concentrations of UA or monosodium urate. Fluorescent metabolites of DCFH-DA in the culture media of HMC were detected at 485/530 nm excitation/emission wavelengths, respectively. UA dose-dependently lowered resting [Ca2+]i (from 102±9 nM to 95±3, 57±2, 48±6 nM at 1-100 uM UA, respectively, p <0.05), leaving responses to vasoconstrictors such as angiotensin II unaffected. The effect was not due to Ca2+/H+ exchange upon acidification of the bathing media, as acetate, glutamate, lactate and other organic acids rather increased [Ca2+]i (to max. levels of 497±42 nM with 0.1 mM acetate). The decrease of [Ca2+]i was abolished by raising extracellular Ca2+ and not due to effects on Ca2+ channels or activation of Ca2+-ATPases, since unaffected by thapsigargin. The process rather appeared sensitive to removal of extracellular Na+ in combination with blockers of Na+/Ca2+ exchange, such as 2’,4’-dichlorobenzamil, pointing to a countertransport mechanism. UA dose-dependently prompted the extracellular release of oxidised DCFH (control 37±2 relative fluorescence units (RFU)/ml, 0.1uM 47±2, 1 uM 48±2, 10 uM 51±4, 0.1 mM 53±4; positive control, 10 uM sodium nitroprusside 92±5 RFU/ml, p<0.01). In summary, UA interferes with Ca2+ transport in cultured HMC, triggering oxidative stress which may initiate a sequence of events leading to interstitial injury and possibly amplifying renal vascular damage and/or the progression of chronic disease.

Progetto di reti Sensori Wireless e tecniche di Fusione Sensoriale

Ambient Intelligence (AmI) envisions a world where smart, electronic environments are aware and responsive to their context. People moving into these settings engage many computational devices and systems simultaneously even if they are not aware of their presence. AmI stems from the convergence of three key technologies: ubiquitous computing, ubiquitous communication and natural interfaces. The dependence on a large amount of fixed and mobile sensors embedded into the environment makes of Wireless Sensor Networks one of the most relevant enabling technologies for AmI. WSN are complex systems made up of a number of sensor nodes, simple devices that typically embed a low power computational unit (microcontrollers, FPGAs etc.), a wireless communication unit, one or more sensors and a some form of energy supply (either batteries or energy scavenger modules). Low-cost, low-computational power, low energy consumption and small size are characteristics that must be taken into consideration when designing and dealing with WSNs. In order to handle the large amount of data generated by a WSN several multi sensor data fusion techniques have been developed. The aim of multisensor data fusion is to combine data to achieve better accuracy and inferences than could be achieved by the use of a single sensor alone. In this dissertation we present our results in building several AmI applications suitable for a WSN implementation. The work can be divided into two main areas: Multimodal Surveillance and Activity Recognition. Novel techniques to handle data from a network of low-cost, low-power Pyroelectric InfraRed (PIR) sensors are presented. Such techniques allow the detection of the number of people moving in the environment, their direction of movement and their position. We discuss how a mesh of PIR sensors can be integrated with a video surveillance system to increase its performance in people tracking. Furthermore we embed a PIR sensor within the design of a Wireless Video Sensor Node (WVSN) to extend its lifetime. Activity recognition is a fundamental block in natural interfaces. A challenging objective is to design an activity recognition system that is able to exploit a redundant but unreliable WSN. We present our activity in building a novel activity recognition architecture for such a dynamic system. The architecture has a hierarchical structure where simple nodes performs gesture classification and a high level meta classifiers fuses a changing number of classifier outputs. We demonstrate the benefit of such architecture in terms of increased recognition performance, and fault and noise robustness. Furthermore we show how we can extend network lifetime by performing a performance-power trade-off. Smart objects can enhance user experience within smart environments. We present our work in extending the capabilities of the Smart Micrel Cube (SMCube), a smart object used as tangible interface within a tangible computing framework, through the development of a gesture recognition algorithm suitable for this limited computational power device. Finally the development of activity recognition techniques can greatly benefit from the availability of shared dataset. We report our experience in building a dataset for activity recognition. Such dataset is freely available to the scientific community for research purposes and can be used as a testbench for developing, testing and comparing different activity recognition techniques.

New high nuclearity carbonyl clusters

The thesis reports the synthesis, and the chemical, structural and spectroscopic characterization of a series of new Rhodium and Au-Fe carbonyl clusters. Most new high-nuclearity rhodium carbonyl clusters have been obtained by redox condensation of preformed rhodium clusters reacting with a species in a different oxidation state generated in situ by mild oxidation. In particular the starting Rh carbonyl clusters is represented by the readily available [Rh7(CO)16]3- 9 compound. The oxidized species is generated in situ by reaction of the above with a stoichiometric defect of a mild oxidizing agents such as [M(H2O)x]n+ aquo complexes possessing different pKa’s and Mn+/M potentials. The experimental results are roughly in keeping with the conclusion that aquo complexes featuring E°(Mn+/M) < ca. -0.20 V do not lead to the formation of hetero-metallic Rh clusters, probably because of the inadequacy of their redox potentials relative to that of the [Rh7(CO)16]3-/2- redox couple. Only homometallic cluster s such as have been fairly selectively obtained. As a fallout of the above investigations, also a convenient and reproducible synthesis of the ill-characterized species [HnRh22(CO)35]8-n has been discovered. The ready availability of the above compound triggered both its complete spectroscopic and chemical characterization. because it is the only example of Rhodium carbonyl clusters with two interstitial metal atoms. The presence of several hydride atoms, firstly suggested by chemical evidences, has been implemented by ESI-MS and 1H-NMR, as well as new structural characterization of its tetra- and penta-anion. All these species display redox behaviour and behave as molecular capacitors. Their chemical reactivity with CO gives rise to a new series of Rh22 clusters containing a different number of carbonyl groups, which have been likewise fully characterized. Formation of hetero-metallic Rh clusters was only observed when using SnCl2H2O as oxidizing agent because. Quite all the Rh-Sn carbonyl clusters obtained have icosahedral geometry. The only previously reported example of an icosahedral Rh cluster with an interstitial atom is the [Rh12Sb(CO)27]3- trianion. They have very similar metal framework, as well as the same number of CO ligands and, consequently, cluster valence electrons (CVEs). .A first interesting aspect of the chemistry of the Rh-Sn system is that it also provides icosahedral clusters making exception to the cluster-borane analogy by showing electron counts from 166 to 171. As a result, the most electron-short species, namely [Rh12Sn(CO)25]4- displays redox propensity, even if disfavoured by the relatively high free negative charge of the starting anion and, moreover, behaves as a chloride scavenger. The presence of these bulky interstitial atoms results in the metal framework adopting structures different from a close-packed metal lattice and, above all, imparts a notable stability to the resulting cluster. An organometallic approach to a new kind of molecular ligand-stabilized gold nanoparticles, in which Fe(CO)x (x = 3,4) moieties protect and stabilize the gold kernel has also been undertaken. As a result, the new clusters [Au21{Fe(CO)4}10]5-, [Au22{Fe(CO)4}12]6-, Au28{Fe(CO)3}4{Fe(CO)4}10]8- and [Au34{Fe(CO)3}6{Fe(CO)4}8]6- have been isolated and characterized. As suggested by concepts of isolobal analogies, the Fe(CO)4 molecular fragment may display the same ligand capability of thiolates and go beyond. Indeed, the above clusters bring structural resemblance to the structurally characterized gold thiolates by showing Fe-Au-Fe, rather than S-Au-S, staple motives. Staple motives, the oxidation state of surface gold atoms and the energy of Au atomic orbitals are likely to concur in delaying the insulator-to-metal transition as the nuclearity of gold thiolates increases, relative to the more compact transition-metal carbonyl clusters. Finally, a few previously reported Au-Fe carbonyl clusters have been used as precursors in the preparation of supported gold catalysts. The catalysts obtained are active for toluene oxidation and the catalytic activity depends on the Fe/Au cluster loading over TiO2.

Sistemi riconfigurabili a basso consumo per applicazioni di monitoraggio distribuito

The term Ambient Intelligence (AmI) refers to a vision on the future of the information society where smart, electronic environment are sensitive and responsive to the presence of people and their activities (Context awareness). In an ambient intelligence world, devices work in concert to support people in carrying out their everyday life activities, tasks and rituals in an easy, natural way using information and intelligence that is hidden in the network connecting these devices. This promotes the creation of pervasive environments improving the quality of life of the occupants and enhancing the human experience. AmI stems from the convergence of three key technologies: ubiquitous computing, ubiquitous communication and natural interfaces. Ambient intelligent systems are heterogeneous and require an excellent cooperation between several hardware/software technologies and disciplines, including signal processing, networking and protocols, embedded systems, information management, and distributed algorithms. Since a large amount of fixed and mobile sensors embedded is deployed into the environment, the Wireless Sensor Networks is one of the most relevant enabling technologies for AmI. WSN are complex systems made up of a number of sensor nodes which can be deployed in a target area to sense physical phenomena and communicate with other nodes and base stations. These simple devices typically embed a low power computational unit (microcontrollers, FPGAs etc.), a wireless communication unit, one or more sensors and a some form of energy supply (either batteries or energy scavenger modules). WNS promises of revolutionizing the interactions between the real physical worlds and human beings. Low-cost, low-computational power, low energy consumption and small size are characteristics that must be taken into consideration when designing and dealing with WSNs. To fully exploit the potential of distributed sensing approaches, a set of challengesmust be addressed. Sensor nodes are inherently resource-constrained systems with very low power consumption and small size requirements which enables than to reduce the interference on the physical phenomena sensed and to allow easy and low-cost deployment. They have limited processing speed,storage capacity and communication bandwidth that must be efficiently used to increase the degree of local ”understanding” of the observed phenomena. A particular case of sensor nodes are video sensors. This topic holds strong interest for a wide range of contexts such as military, security, robotics and most recently consumer applications. Vision sensors are extremely effective for medium to long-range sensing because vision provides rich information to human operators. However, image sensors generate a huge amount of data, whichmust be heavily processed before it is transmitted due to the scarce bandwidth capability of radio interfaces. In particular, in video-surveillance, it has been shown that source-side compression is mandatory due to limited bandwidth and delay constraints. Moreover, there is an ample opportunity for performing higher-level processing functions, such as object recognition that has the potential to drastically reduce the required bandwidth (e.g. by transmitting compressed images only when something ‘interesting‘ is detected). The energy cost of image processing must however be carefully minimized. Imaging could play and plays an important role in sensing devices for ambient intelligence. Computer vision can for instance be used for recognising persons and objects and recognising behaviour such as illness and rioting. Having a wireless camera as a camera mote opens the way for distributed scene analysis. More eyes see more than one and a camera system that can observe a scene from multiple directions would be able to overcome occlusion problems and could describe objects in their true 3D appearance. In real-time, these approaches are a recently opened field of research. In this thesis we pay attention to the realities of hardware/software technologies and the design needed to realize systems for distributed monitoring, attempting to propose solutions on open issues and filling the gap between AmI scenarios and hardware reality. The physical implementation of an individual wireless node is constrained by three important metrics which are outlined below. Despite that the design of the sensor network and its sensor nodes is strictly application dependent, a number of constraints should almost always be considered. Among them: • Small form factor to reduce nodes intrusiveness. • Low power consumption to reduce battery size and to extend nodes lifetime. • Low cost for a widespread diffusion. These limitations typically result in the adoption of low power, low cost devices such as low powermicrocontrollers with few kilobytes of RAMand tenth of kilobytes of program memory with whomonly simple data processing algorithms can be implemented. However the overall computational power of the WNS can be very large since the network presents a high degree of parallelism that can be exploited through the adoption of ad-hoc techniques. Furthermore through the fusion of information from the dense mesh of sensors even complex phenomena can be monitored. In this dissertation we present our results in building several AmI applications suitable for a WSN implementation. The work can be divided into two main areas:Low Power Video Sensor Node and Video Processing Alghoritm and Multimodal Surveillance . Low Power Video Sensor Nodes and Video Processing Alghoritms In comparison to scalar sensors, such as temperature, pressure, humidity, velocity, and acceleration sensors, vision sensors generate much higher bandwidth data due to the two-dimensional nature of their pixel array. We have tackled all the constraints listed above and have proposed solutions to overcome the current WSNlimits for Video sensor node. We have designed and developed wireless video sensor nodes focusing on the small size and the flexibility of reuse in different applications. The video nodes target a different design point: the portability (on-board power supply, wireless communication), a scanty power budget (500mW),while still providing a prominent level of intelligence, namely sophisticated classification algorithmand high level of reconfigurability. We developed two different video sensor node: The device architecture of the first one is based on a low-cost low-power FPGA+microcontroller system-on-chip. The second one is based on ARM9 processor. Both systems designed within the above mentioned power envelope could operate in a continuous fashion with Li-Polymer battery pack and solar panel. Novel low power low cost video sensor nodes which, in contrast to sensors that just watch the world, are capable of comprehending the perceived information in order to interpret it locally, are presented. Featuring such intelligence, these nodes would be able to cope with such tasks as recognition of unattended bags in airports, persons carrying potentially dangerous objects, etc.,which normally require a human operator. Vision algorithms for object detection, acquisition like human detection with Support Vector Machine (SVM) classification and abandoned/removed object detection are implemented, described and illustrated on real world data. Multimodal surveillance: In several setup the use of wired video cameras may not be possible. For this reason building an energy efficient wireless vision network for monitoring and surveillance is one of the major efforts in the sensor network community. Energy efficiency for wireless smart camera networks is one of the major efforts in distributed monitoring and surveillance community. For this reason, building an energy efficient wireless vision network for monitoring and surveillance is one of the major efforts in the sensor network community. The Pyroelectric Infra-Red (PIR) sensors have been used to extend the lifetime of a solar-powered video sensor node by providing an energy level dependent trigger to the video camera and the wireless module. Such approach has shown to be able to extend node lifetime and possibly result in continuous operation of the node.Being low-cost, passive (thus low-power) and presenting a limited form factor, PIR sensors are well suited for WSN applications. Moreover techniques to have aggressive power management policies are essential for achieving long-termoperating on standalone distributed cameras needed to improve the power consumption. We have used an adaptive controller like Model Predictive Control (MPC) to help the system to improve the performances outperforming naive power management policies.

Ribosome-inactivating proteins and their immunotoxins for cancer therapy: insights into the mechanism of cell death

Ribosome-inactivating proteins (RIPs) are a family of plant toxic enzymes that permanently damage ribosomes and possibly other cellular substrates, thus causing cell death involving different and still not completely understood pathways. The high cytotoxic activity showed by many RIPs makes them ideal candidates for the production of immunotoxins (ITs), chimeric proteins designed for the selective elimination of unwanted or malignant cells. Saporin-S6, a type 1 RIP extracted from Saponaria officinalis L. seeds, has been extensively employed to construct anticancer conjugates because of its high enzymatic activity, stability and resistance to conjugation procedures, resulting in the efficient killing of target cells. Here we investigated the anticancer properties of two saporin-based ITs, anti-CD20 RTX/S6 and anti-CD22 OM124/S6, designed for the experimental treatment of B-cell NHLs. Both ITs showed high cytotoxicity towards CD20-positive B-cells, and their antitumor efficacy was enhanced synergistically by a combined treatment with proteasome inhibitors or fludarabine. Furthermore, the two ITs showed differencies in potency and ability to activate effector caspases, and a different behavior in the presence of the ROS scavenger catalase. Taken together, these results suggest that the different carriers employed to target saporin might influence saporin intracellular routing and saporin-induced cell death mechanisms. We also investigated the early cellular response to stenodactylin, a recently discovered highly toxic type 2 RIP representing an interesting candidate for the design and production of a new IT for the experimental treatment of cancer.