Epileptiform Activity in Isolated Cortex and Hippocampal Preparations, and Its Modulation by Purinergic Compounds

1. This dissertation addresses both the physical requirements (in terms of the minimal mass of tissue needed) for the generation and propagation of epileptiform activity, and the purinergic modulation of this epileptiform activity in the cerebral cortex. Studies on the minimal mass were performed in rat somatosensory cortex in vivo, using subpial transsections based on a recently developed neurosurgical approach to the treatment of drug-resistant epilepsy (Morrell et al 1989: "Multiple subpial transection: a new approach to the surgical treatment of focal epilepsy"), in conjunction with the iontophoretic application of the convulsant penicillin. For a detailed analysis of the structural requirements for epileptiform activity and the rapid application and wash-out of drugs of known concentration, a novel in vitro model of the isolated neocortical column was developed which allowed the manipulation of radial intracortical pathways via pressure ejection of drugs at various cortical depths, and the isolation of specific layers by subsectioning the tissue. It therefore provided a unique way of studying the intrinsic pathways of individual cortical layers. The epileptiform potentials in rat and mouse neocortical cylinders were recorded with standard extracellular recording techniques in an attempt to elucidate some of the aspects of the ongoing debate on whether the so-called 'cortical columns' are hardwired information processing units, or functional groups of co-active neurones whose configuration varies with the task performed. 2. After preliminary findings in rat neocortex in vivo had indicated that the minimal mass, i.e. the smallest block of cortical brain tissue able to generate epileptiform spiking, was small enough to be investigated in vitro, work on the subsequently developed in vitro model of the cortical column clearly showed that the minimal diameter was below that of the postulated columns defined by the so-called 'barrel' structures found in layer IV of the rat somatosensory cortex. Furthermore, blocks of brain tissue (containing an estimated 1500 neurones) which excluded layer IV displayed epileptiform activity which was indistinguishable from that observed in preparations containing all neocortical layers, or indeed from records obtained by other groups in chronically isolated neocortex in situ. It is concluded that the minimal mass problem is, to a certain extent, merely a question of the degree of connectivity; from the results of the present study, no horizontal boundaries corresponding to the postulated 'cortical modules' were found to exist with respect to the generation of paroxysmal discharges. Similarly, the importance of layer IV in the generation of epileptiform discharges appears to pertain only to the specialised case of discharges induced by GABA receptor blockade, as exclusion of this layer did not affect the ability of the tissue to display the spikes/afterdischarges commonly observed in intact cortical slices in vitro, and in cortical subpial isolations in vivo. 3. In Part Two, the purinergic modulation of this epileptiform activity was studied in mouse neocortical cylinders and in rat hippocampal slices. The inhibitory effects of adenosine (a metabolite of nucleotide hydrolysis which may act as an 'endogenous anticonvulsant') on low-magnesium ACSF-induced epileptiform activity are described, followed by an analysis of the factors contributing to the proconvulsant effects caused by selective adenosine A1 receptor blockade in vitro. The main compound used was l,3-dipropyl-8-cyclopentyl-xanthine (DPCPX), a highly selective A1 antagonist which in previous in vitro studies had been reported to induce persistent epileptiform activity by an unknown mechanism after transient application; these prolonged epileptogenic effects are not usually observed after the application of less selective adenosine antagonists. 4. Despite the marked proconvulsant effects reported for DPCPX in vitro, the drug does not induce seizures when administered in vivo. A similar effect was observed in the present study in vitro', on the basis of these findings, it is suggested that the main physiological role of adenosine in the brain is to exert an activity-dependent negative feedback control which limits the effects of calcium influx through voltage-activated Ca++ channels, rather than the 'inhibitory purinergic tone' proposed by some authors

Genome-wide Analyses Identify KIF5A as a Novel ALS Gene

To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe

EVALITA Evaluation of NLP and Speech Tools for Italian - December 17th, 2020

Welcome to EVALITA 2020! EVALITA is the evaluation campaign of Natural Language Processing and Speech Tools for Italian. EVALITA is an initiative of the Italian Association for Computational Linguistics (AILC, http://www.ai-lc.it) and it is endorsed by the Italian Association for Artificial Intelligence (AIxIA, http://www.aixia.it) and the Italian Association for Speech Sciences (AISV, http://www.aisv.it)

Optimizing Silicon photomultipliers for Quantum Optics

Silicon Photomultipliers are potentially ideal detectors for Quantum Optics and Quantum Information studies based on mesoscopic states of light. However, their non-idealities hampered their use so far. An optimal mode of operation has been developed and it is presented here, proving that this class of sensors can actually be exploited for the characterization of both classical and quantum properties of light

Multiple Myeloma, an update on diagnosis and treatment.

Multiple myeloma is a plasma cell (PC) malignancy characterized by the accumulation of monoclonal PCs in the bone marrow and the production of large amounts of a monoclonal immunoglobulin or paraprotein. In the past years, new approaches in the diagnosis and treatment were introduced aiming to identify high-risk patients who need proper anti-myeloma treatment. Intensive therapy including autologous hematopoietic stem cell transplantation and the new agents bortezomib, thalidomide, and lenalidomide have improved patients' responses. Further optimalization of the different treatment schedules in well-defined patient groups may prolong their survival. Patient stratification is currently based on patient characteristics, extent of myeloma disease, and associated cytogenetic and laboratory anomalies. More and more gene expression studies are introduced to stratify patients and to individualize therapy