449 research outputs found

    Surveillance for the Management of Small Renal Masses

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    Surveillance is a new management option for small renal masses (SRMs) in aged and infirm patients with short-life expectancy. The current literature on surveillance of SRM contains mostly small, retrospective studies with limited data. Imaging alone is inadequate for suggesting the aggressive potential of SRM for both diagnosis and followup. Current data suggest that a computed tomography (CT) or magnetic resonance imaging (MRI) every 3 months in the 1st year, every 6 months in the next 2 years, and every year thereafter, is appropriate for observation. The authors rather believe in active surveillance with mandatory initial and followup renal tumor biopsies than classical observation. Since not all SRMs are harmless, selection criteria for active surveillance need to be improved. In addition, there is need for larger studies in order to better outline oncological outcome and followup protocols

    Cellular Plasticity of CD4+ T Cells in the Intestine

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    Barrier sites such as the gastrointestinal tract are in constant contact with the environment which contains both beneficial and harmful components. The immune system at the epithelia must make the distinction between these components to balance tolerance, protection and immunopathology. This is achieved via multifaceted immune recognition, highly organised lymphoid structures and the interaction of many types of immune cells. The adaptive immune response in the gut is orchestrated by CD4+ helper T (Th) cells which are integral to gut immunity. In recent years it has become apparent that the functional identity of these Th cells is not as fixed as initially thought. Plasticity in differentiated T cell subsets has now been firmly established, in both health and disease. The gut, in particular, utilises CD4+ T cell plasticity to mould CD4+ T cell phenotypes to maintain its finely poised balance of tolerance and inflammation and to encourage biodiversity within the enteric microbiome. In this review we will discuss intestinal helper T cell plasticity and our current understanding of its mechanisms, including our growing knowledge of an evolutionarily ancient symbiosis between microbiota and malleable CD4+ T cell effectors

    Structure Learning in a Sensorimotor Association Task

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    Learning is often understood as an organism's gradual acquisition of the association between a given sensory stimulus and the correct motor response. Mathematically, this corresponds to regressing a mapping between the set of observations and the set of actions. Recently, however, it has been shown both in cognitive and motor neuroscience that humans are not only able to learn particular stimulus-response mappings, but are also able to extract abstract structural invariants that facilitate generalization to novel tasks. Here we show how such structure learning can enhance facilitation in a sensorimotor association task performed by human subjects. Using regression and reinforcement learning models we show that the observed facilitation cannot be explained by these basic models of learning stimulus-response associations. We show, however, that the observed data can be explained by a hierarchical Bayesian model that performs structure learning. In line with previous results from cognitive tasks, this suggests that hierarchical Bayesian inference might provide a common framework to explain both the learning of specific stimulus-response associations and the learning of abstract structures that are shared by different task environments

    Influence of spiking activity on cortical local field potentials.

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    The intra-cortical local field potential (LFP) reflects a variety of electrophysiological processes including synaptic inputs to neurons and their spiking activity. It is still a common assumption that removing high frequencies, often above 300 Hz, is sufficient to exclude spiking activity from LFP activity prior to analysis. Conclusions based on such supposedly spike-free LFPs can result in false interpretations of neurophysiological processes and erroneous correlations between LFPs and behaviour or spiking activity. Such findings might simply arise from spike contamination rather than from genuine changes in synaptic input activity. Although the subject of recent studies, the extent of LFP contamination by spikes is unclear, and the fundamental problem remains. Using spikes recorded in the motor cortex of the awake monkey, we investigated how different factors, including spike amplitude, duration and firing rate, together with the noise statistic, can determine the extent to which spikes contaminate intra-cortical LFPs. We demonstrate that such contamination is realistic for LFPs with a frequency down to ∼10 Hz. For LFP activity below ∼10 Hz, such as movement-related potential, contamination is theoretically possible but unlikely in real situations. Importantly, LFP frequencies up to the (high-) gamma band can remain unaffected. This study shows that spike-LFP crosstalk in intra-cortical recordings should be assessed for each individual dataset to ensure that conclusions based on LFP analysis are valid. To this end, we introduce a method to detect and to visualise spike contamination, and provide a systematic guide to assess spike contamination of intra-cortical LFPs

    Tbet or Continued RORγt Expression Is Not Required for Th17-Associated Immunopathology

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    The discovery of Th17 cell plasticity, in which CD4 + IL-17-producing Th17 cells give rise to IL-17/IFN-γ double-producing cells and Th1-like IFNγ+ ex-Th17 lymphocytes, has raised questions regarding which of these cell types contribute to immunopathology during inflammatory diseases. In this study, we show using Helicobacter hepaticus-induced intestinal inflammation that IL-17ACre- or Rag1Cre-mediated deletion of Tbx21 has no effect on the generation of IL-17/IFN-g double-producing cells, but leads to a marked absence of Th1-like IFNγ+ ex-Th17 cells. Despite the lack of Th1-like ex-Th17 cells, the degree of H. hepaticus-Triggered intestinal inflammation in mice in which Tbx21 was excised in IL-17-producing or Rag1-expressing cells is indistinguishable from that observed in control mice. In stark contrast, using experimental autoimmune encephalomyelitis, we show that IL-17ACre-mediated deletion of Tbx21 prevents the conversion of Th17 cells to IL-17A/IFN-γ double-producing cells as well as Th1-like IFN-γ+ ex-Th17 cells. However, IL-17ACre-mediated deletion of Tbx21 has only limited effects on disease course in this model and is not compensated by Ag-specific Th1 cells. IL-17ACre-mediated deletion of Rorc reveals that RORγt is essential for the maintenance of the Th17 cell lineage, but not immunopathology during experimental autoimmune encephalomyelitis. These results show that neither the single Th17 subset, nor its progeny, is solely responsible for immunopathology or autoimmunity

    A New Synthetic Conduit for the Treatment of Peripheral Nerve Injuries

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    Background Peripheral nerve defects (PND) often cause lifelong physical disability, and the available treatment options are often not satisfactory. PND are usually bridged with an autologous nerve transplant or a nerve guidance conduit (NGC), when coaptation as preferred technique is not possible. The aim of this experimental study was to determine the effectiveness of a novel NGC for regeneration in the treatment of PND. Materials and methods A conduit made of gelatin with an innovative interior structure was tested for the repair of a 6-mm gap versus direct microsurgical suture repair without gap. Results We found that bridging the defect with this conduit was as effective as direct microsurgical coaptation without a defect. Conclusions This nerve conduit, effective in bridging neural defects, appears as an alternative to autologous nerve grafts, avoiding the problems related to nerve graft harvesting, host–donor differences in diameter, mismatches in number and pattern of fascicles, cross-sectional shape and area, and morbidity of the donor area

    Review of the BCI Competition IV

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    The BCI competition IV stands in the tradition of prior BCI competitions that aim to provide high quality neuroscientific data for open access to the scientific community. As experienced already in prior competitions not only scientists from the narrow field of BCI compete, but scholars with a broad variety of backgrounds and nationalities. They include high specialists as well as students. The goals of all BCI competitions have always been to challenge with respect to novel paradigms and complex data. We report on the following challenges: (1) asynchronous data, (2) synthetic, (3) multi-class continuous data, (4) session-to-session transfer, (5) directionally modulated MEG, (6) finger movements recorded by ECoG. As after past competitions, our hope is that winning entries may enhance the analysis methods of future BCIs.BMBF, 01IB001A, LOKI - Lernen zur Organisation komplexer Systeme der Informationsverarbeitung - Lernen im Kontext der SzenenanalyseBMBF, 01GQ0850, Bernstein Fokus Neurotechnologie - Nichtinvasive Neurotechnologie für Mensch-Maschine InteraktionEC/FP7/224631/EU/Tools for Brain-Computer Interaction/TOBIEC/FP7/216886/EU/Pattern Analysis, Statistical Modelling and Computational Learning 2/PASCAL2BMBF, 01GQ0420, Verbundprojekt: Bernstein-Zentrum für Neural Dynamics, Freiburg - CNDFBMBF, 01GQ0761, Bewegungsassoziierte Aktivierung - Dekodierung bewegungsassoziierter GehirnsignaleBMBF, 01GQ0762, Bewegungsassoziierte Aktivierung - Gehirn- und Maschinenlerne

    Tumour architecture is an independent predictor of outcomes after nephroureterectomy: a multi-institutional analysis of 1363 patients

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    To assess whether tumour architecture can help to refine the prognosis of patients treated with nephroureterectomy (NU) for urothelial carcinoma (UC) of the upper urinary tract (UT), as the prognostic value of tumour architecture (papillary vs sessile) in UTUC remains elusive. PATIENTS AND METHODS The study included 1363 patients with UTUC and treated with radical NU at 12 centres worldwide. All slides were re-reviewed according to strict criteria by genitourinary pathologists who were unaware of the findings of the original pathology slides and clinical outcomes. Gross tumour architecture was categorized as sessile vs papillary. RESULTS Papillary growth was identified in 983 patients (72.2%) and sessile growth in 380 (27.8%). The sessile growth pattern was associated with higher tumour grade, more advanced stage, lymphovascular invasion, and metastasis to lymph nodes (all P  < 0.001). In multivariable Cox regression analyses that adjusted for the effects of pathological stage, grade and lymph node status, tumour architecture (sessile or papillary) was an independent predictor of cancer recurrence (hazard ratio 1.5, P  = 0.002) and cancer-specific mortality (1.6, P  = 0.001). Adding tumour architecture increased the predictive accuracy of a model that comprised pathological stage, grade and lymph node status for predicting cancer recurrence and cancer-specific death by a minimal but statistically significant margin (gain in predictive accuracy 1% and 0.5%, both P  < 0.001). CONCLUSION The tumour architecture of UTUC is associated with established features of biologically aggressive disease, and more importantly, with prognosis after radical NU. Including tumour architecture in predictive models for disease progression should be considered, aiming to identify patients who might benefit from early systemic therapeutic intervention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72257/1/j.1464-410X.2008.08003.x.pd

    Decoding Imagined 3D Hand Movement Trajectories From EEG: Evidence to Support the Use of Mu, Beta, and Low Gamma Oscillations

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    Objective: To date, motion trajectory prediction (MTP) of a limb from non-invasive electroencephalography (EEG) has relied, primarily, on band-pass filtered samples of EEG potentials i.e., the potential time-series model. Most MTP studies involve decoding 2D and 3D arm movements i.e., executed arm movements. Decoding of observed or imagined 3D movements has been demonstrated with limited success and only reported in a few studies. MTP studies normally use EEG potentials filtered in the low delta (~1 Hz) band for reconstructing the trajectory of an executed or an imagined/observed movement. In contrast to MTP, multiclass classification based sensorimotor rhythm brain-computer interfaces aim to classify movements using the power spectral density of mu (8–12 Hz) and beta (12–28 Hz) bands.Approach: We investigated if replacing the standard potentials time-series input with a power spectral density based bandpower time-series improves trajectory decoding accuracy of kinesthetically imagined 3D hand movement tasks (i.e., imagined 3D trajectory of the hand joint) and whether imagined 3D hand movements kinematics are encoded also in mu and beta bands. Twelve naïve subjects were asked to generate or imagine generating pointing movements with their right dominant arm to four targets distributed in 3D space in synchrony with an auditory cue (beep).Main results: Using the bandpower time-series based model, the highest decoding accuracy for motor execution was observed in mu and beta bands whilst for imagined movements the low gamma (28–40 Hz) band was also observed to improve decoding accuracy for some subjects. Moreover, for both (executed and imagined) movements, the bandpower time-series model with mu, beta, and low gamma bands produced significantly higher reconstruction accuracy than the commonly used potential time-series model and delta oscillations.Significance: Contrary to many studies that investigated only executed hand movements and recommend using delta oscillations for decoding directional information of a single limb joint, our findings suggest that motor kinematics for imagined movements are reflected mostly in power spectral density of mu, beta and low gamma bands, and that these bands may be most informative for decoding 3D trajectories of imagined limb movements
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