Tactile cognition in rodents

Since the discovery 50 years ago of the precisely ordered representation of the whiskers in somatosensory cortex, the rodent tactile sensory system has been a fertile ground for the study of sensory processing. With the growing sophistication of touch-based behavioral paradigms, together with advances in neurophysiological methodology, a new approach is emerging. By posing increasingly complex perceptual and memory problems, in many cases analogous to human psychophysical tasks, investigators now explore the operations underlying rodent problem solving. We define the neural basis of tactile cognition as the transformation from a stage in which neuronal activity encodes elemental features, local in space and in time, to a stage in which neuronal activity is an explicit representation of the behavioral operations underlying the current task. Selecting a set of whisker-based behavioral tasks, we show that rodents achieve high level performance through the workings of neuronal cir-cuits that are accessible, decodable, and manipulatable. As a means towards exploring tactile cognition, this review presents leading psychophysical paradigms and, where known, their neural correlates

Upward displacement of the odontoid process into the foramen magnum: a palaeopathological case

An upward displacement of the odontoid process into the foramen magnum was observed in the skeletal remains of a young male unearthed from a 14th to 17th century cemetery in the north-eastern Italy. Examination of skull bone vestiges and computed tomography scan analysis of the axis exhibited a clear-cut contact zone between the odontoid process and the anterior border of the foramen magnum. In addition, the odontoid process appeared backward deviated. Findings suggest a possible diagnosis of basilar impression/invagination. This anomalous contact may cause compression of neural and vascular structures with a multifaceted series of clinical symptoms. We are unable to set our finding into a complete presumptive diagnostic outline because there is no chance to estimate either the magnitude of the whole craniovertebral junction defect but we believe that the present case contributes to the general knowledge of the craniovertebral region and to bone pathology in ancient times

A sensory integration account for time perception

The connection between stimulus perception and time perception remains unknown. The present study combines human and rat psychophysics with sensory cortical neuronal firing to construct a computational model for the percept of elapsed time embedded within sense of touch. When subjects judged the duration of a vibration applied to the fingertip (human) or whiskers (rat), increasing stimulus intensity led to increasing perceived duration. Symmetrically, increasing vibration duration led to increasing perceived intensity. We modeled spike trains from vibrissal somatosensory cortex as input to dual leaky integrators \u2013 an intensity integrator with short time constant and a duration integrator with long time constant \u2013 generating neurometric functions that replicated the actual psychophysical functions of rats. Returning to human psychophysics, we then confirmed specific predictions of the dual leaky integrator model. This study offers a framework, based on sensory coding and subsequent accumulation of sensory drive, to account for how a feeling of the passage of time accompanies the tactile sensory experience

Capitate-trapezoid synostosis: analysis of an Early Bronze Age case and review of the literature

Background: Carpal synostoses are congenital defects characterised by complete or incomplete coalition of two or more carpal bones. Although most of these defects are discovered only incidentally, sometimes they become clinically manifest. Among the different types of carpal coalition, the synostosis between capitate and trapezoid bones is quite rare, with only sparse data available in the literature. The aim of this report was to describe a case of capitate-trapezoid synostosis (CTS) observed in an ancient human skeleton, as well as to scrutinise the pertinent literature in order to assess for the characteristics of this type of defect, including its potential relevance to clinical practice. Materials and methods: We studied the skeletal remains of an Early Bronze Age male warrior affected by incomplete CTS. Macroscopic and radiological examination of the defect was carried out. We also performed a comprehensive PubMed search in the Medline and other specialty literature databases to retrieve and analyse data relevant to the subject under consideration. Results and Conclusions: The present case is the most ancient CTS ever found. In those literature-reported cases accompanied by careful anatomical description, such as the present one, incomplete coalition invariably occurs between the dorsal surfaces of the two bones, this characteristic emerging as a distinctive morphological trait. Literature analysis further suggests that the true prevalence of CTS is likely to be higher than estimates based on data gathered from radiology series, and that this defect may be associated with pain and carpal bossing more frequently than generally though

Predictive value of hematological and phenotypical parameters on postchemotherapy leukocyte recovery

Background: Grade IV chemotherapy toxicity is defined as absolute neutrophil count <500/μL. The nadir is considered as the lowest neutrophil number following chemotherapy, and generally is not expected before the 7th day from the start of chemotherapy. The usual prophylactic dose of rHu-G-CSF (Filgrastim) is 300 μg/day, starting 24-48 h after chemotherapy until hematological recovery. However, individual patient response is largely variable, so that rHu-G-CSF doses can be different. The aim of this study was to verify if peripheral blood automated flow cytochemistry and flow cytometry analysis may be helpful in predicting the individual response and saving rHu-G-CSF. Methods: During Grade IV neutropenia, blood counts from 30 cancer patients were analyzed daily by ADVIA 120 automated flow cytochemistry analyzer and by Facscalibur flow cytometer till the nadir. "Large unstained cells" (LUCs), myeloperoxidase index (MPXI), blasts, and various cell subpopulations in the peripheral blood were studied. At nadir rHu-G-CSF was started and 81 chemotherapy cycles were analyzed. Cycles were stratified according to their number and to two dose-levels of rHuG-CSF needed to recovery (300-600 vs. 900-1200 μg) and analyzed in relation to mean values of MPXI and mean absolute number of LUCs in the nadir phase. The linear regressions of LUCs % over time in relation to two dose-levels of rHu-G-CSF and uni-multivariate analysis of lymphocyte subpopulations, CD34+ cells, MPXI, and blasts were also performed. Results: In the nadir phase, the increase of MPXI above the upper limit of normality (>10; median 27.7), characterized a slow hematological recovery. MPXI levels were directly related to the cycle number and inversely related to the absolute number of LUCs and CD34 +/CD45+ cells. A faster hematological recovery was associated with a higher LUC increase per day (0.56% vs. 0.25%), higher blast (median 36.7/μL vs. 19.5/μL) and CD34+/CD45+ cell (median 2.2/μL vs. 0.82/μL) counts. Conclusions: Our study showed that some biological indicators such as MPXI, LUCs, blasts, and CD34 +/CD45+ cells may be of clinical relevance in predicting individual hematological response to rHu-G-CSF. Special attention should be paid when nadir MPXI exceeds the upper limit of normality because the hematological recovery may be delayed. © 2009 Clinical Cytometry Society

Liver transplantation for colorectal liver metastasis: Survival without recurrence can be achieved

info:eu-repo/semantics/publishedVersio

Kinetochore alignment within the metaphase plate is regulated by centromere stiffness and microtubule depolymerases

During mitosis in most eukaryotic cells, chromosomes align and form a metaphase plate halfway between the spindle poles, about which they exhibit oscillatory movement. These movements are accompanied by changes in the distance between sister kinetochores, commonly referred to as breathing. We developed a live cell imaging assay combined with computational image analysis to quantify the properties and dynamics of sister kinetochores in three dimensions. We show that baseline oscillation and breathing speeds in late prometaphase and metaphase are set by microtubule depolymerases, whereas oscillation and breathing periods depend on the stiffness of the mechanical linkage between sisters. Metaphase plates become thinner as cells progress toward anaphase as a result of reduced oscillation speed at a relatively constant oscillation period. The progressive slowdown of oscillation speed and its coupling to plate thickness depend nonlinearly on the stiffness of the mechanical linkage between sisters. We propose that metaphase plate formation and thinning require tight control of the state of the mechanical linkage between sisters mediated by centromeric chromatin and cohesion

Energy Absorption Mechanisms in Layer-to-Layer 3D Woven Composites

3D woven composites provide improved out-of-plane performance over their two-dimensional counterparts. This sort of reinforced through thickness behaviour is desirable in crashworthiness applications where energy absorption can be increased by the composite material's resistance to delamination. The behaviour of these 3D materials in not well understood and fundamental data that can be used to validate and improve material models is not yet sufficiently comprehensive. Here we demonstrate that a modified layer-to-layer type 3D woven architecture can be effectively used in energy absorbing elements to produce repeatable and predictable progressive failure under axial crush conditions. Specific energy absorption (SEA) values in glass and carbon coupons of up to 62J/g and 95J/g respectively are achieved in the quasi-static regime; values up 93J/g to were achieved in the dynamic regime when carbon coupons are tested. Carbon specimens displayed uncharacteristic mixed mode failure with elements of ductile and brittle failure. The addition of a toughening agent showed mixed results in this study, providing quasi-static improvements (+8%) in SEA but significant diminishment in dynamic SEA (-22%). The failure modes present in all cases are explored in depth and the suitability of this material for industry crash applications is investigated

Improved crush energy absorption in 3D woven composites by pick density modification

Although 3D woven composites have exceptional out-of-plane properties, there is a lack of understanding for these materials in crash application in automotive and aerospace industries. To encourage the use of 3D wovens in crashworthy automotive structures, knowledge must be gained so that designers can adjust the highly flexible weave parameters to create tailor-made performance materials. Here we show that fabric pick density causes large changes in progressive failure modes and associated energy absorption, particularly in the dynamic regime, where the quasi-static to dynamic energy absorption loss typical of composites is completely removed. Compression and flexure properties, which are known to be linked to crash performance in composites, are also investigated for these 3D woven layer-to-layer interlock carbon-epoxy composite structures. 3D fabric preforms are manufactured in three different pick densities: 4, 10 & 16 wefts/cm. With a constant warp density of 12 warps/cm from carbon fibres. Increasing the pick density improved specific energy absorption (SEA) even in relatively inefficient progressive failure modes like folding, which has not previously observed in composite materials. SEA values up to 104 J/g (quasi-static) and 93 J/g (dynamic) are recorded. This work shows that minor weft direction (transverse) weave changes can lead to sizeable improvements in warp direction (axial) energy absorption without fundamentally redesigning the weave architecture