Neurological recovery after traumatic spinal cord injury:what is meaningful? A patients' and physicians' perspective

Study design: Cross-sectional survey. Objectives: Most studies on neurological recovery after traumatic spinal cord injury (tSCI) assess treatment effects using the American Spinal Injury Association Impairment Scale (AIS grade) or motor points recovery. To what extent neurological recovery is considered clinically meaningful is unknown. This study investigated the perceived clinical benefit of various degrees of neurological recovery one year after C5 AIS-A tSCI. Setting: The Netherlands. Methods: By means of a web-based survey SCI patients and physicians evaluated the benefit of various scenarios of neurological recovery on a scale from 0 to 100% (0% no benefit to 100% major benefit). Recovery to AIS-C and D, was split into C/C+ and D/D+, which was defined by the lower and upper limit of recovery for each grade. Results: A total of 79 patients and 77 physicians participated in the survey. Each AIS grade improvement from AIS-A was considered significant benefit (all p < 0.05), ranging from 47.8% (SD 26.1) for AIS-B to 86.8% (SD 24.3) for AIS-D+. Motor level lowering was also considered significant benefit (p < 0.05), ranging from 66.1% (SD 22.3) for C6 to 81.7% (SD 26.0) for C8. Conclusions: Meaningful recovery can be achieved without improving in AIS grade, since the recovery of functional motor levels appears to be as important as improving in AIS grade by both patients and physicians. Moreover, minor neurological improvements within AIS-C and D are also considered clinically meaningful. Future studies should incorporate more detailed neurological outcomes to prevent potential underestimation of neurological recovery by only using the AIS grade

Volume Tracking: A new method for quantitative assessment and visualization of intracardiac blood flow from three-dimensional, time-resolved, three-component magnetic resonance velocity mapping

<p>Abstract</p> <p>Background</p> <p>Functional and morphological changes of the heart influence blood flow patterns. Therefore, flow patterns may carry diagnostic and prognostic information. Three-dimensional, time-resolved, three-directional phase contrast cardiovascular magnetic resonance (4D PC-CMR) can image flow patterns with unique detail, and using new flow visualization methods may lead to new insights. The aim of this study is to present and validate a novel visualization method with a quantitative potential for blood flow from 4D PC-CMR, called Volume Tracking, and investigate if Volume Tracking complements particle tracing, the most common visualization method used today.</p> <p>Methods</p> <p>Eight healthy volunteers and one patient with a large apical left ventricular aneurysm underwent 4D PC-CMR flow imaging of the whole heart. Volume Tracking and particle tracing visualizations were compared visually side-by-side in a visualization software package. To validate Volume Tracking, the number of particle traces that agreed with the Volume Tracking visualizations was counted and expressed as a percentage of total released particles in mid-diastole and end-diastole respectively. Two independent observers described blood flow patterns in the left ventricle using Volume Tracking visualizations.</p> <p>Results</p> <p>Volume Tracking was feasible in all eight healthy volunteers and in the patient. Visually, Volume Tracking and particle tracing are complementary methods, showing different aspects of the flow. When validated against particle tracing, on average 90.5% and 87.8% of the particles agreed with the Volume Tracking surface in mid-diastole and end-diastole respectively. Inflow patterns in the left ventricle varied between the subjects, with excellent agreement between observers. The left ventricular inflow pattern in the patient differed from the healthy subjects.</p> <p>Conclusion</p> <p>Volume Tracking is a new visualization method for blood flow measured by 4D PC-CMR. Volume Tracking complements and provides incremental information compared to particle tracing that may lead to a better understanding of blood flow and may improve diagnosis and prognosis of cardiovascular diseases.</p

More than Mere Numbers: The Impact of Lethal Control on the Social Stability of a Top-Order Predator

Population control of socially complex species may have profound ecological implications that remain largely invisible if only their abundance is considered. Here we discuss the effects of control on a socially complex top-order predator, the dingo (Canis lupus dingo). Since European occupation of Australia, dingoes have been controlled over much of the continent. Our aim was to investigate the effects of control on their abundance and social stability. We hypothesized that dingo abundance and social stability are not linearly related, and proposed a theoretical model in which dingo populations may fluctuate between three main states: (A) below carrying capacity and socially fractured, (B) above carrying capacity and socially fractured, or (C) at carrying capacity and socially stable. We predicted that lethal control would drive dingoes into the unstable states A or B, and that relaxation of control would allow recovery towards C. We tested our predictions by surveying relative abundance (track density) and indicators of social stability (scent-marking and howling) at seven sites in the arid zone subject to differing degrees of control. We also monitored changes in dingo abundance and social stability following relaxation and intensification of control. Sites where dingoes had been controlled within the previous two years were characterized by low scent-marking activity, but abundance was similar at sites with and without control. Signs of social stability steadily increased the longer an area was allowed to recover from control, but change in abundance did not follow a consistent path. Comparison of abundance and stability among all sites and years demonstrated that control severely fractures social groups, but that the effect of control on abundance was neither consistent nor predictable. Management decisions involving large social predators must therefore consider social stability to ensure their conservation and ecological functioning

Immunological Sex Differences in Socially Promiscuous African Ground Squirrels

Differences in how males and females respond to foreign antigens are common across taxa. Such sexual differences in the immune system are predicted to be greater in species with high promiscuity and sociality as these factors increase the likelihood of disease transmission. Intense sperm competition is thought to further this sexual dichotomy as increased investment in spermatogenesis likely incurs additional immunological costs. Xerus inauris, a ground squirrel found throughout southern Africa, is extremely social and promiscuous with one of the highest male reproductive investments among rodents. These life-history attributes suggest males and females should demonstrate a large dichotomy in immunity. Contrary to our prediction, we found no difference in spleen mass between the sexes. However, we did find significant biases in leukocyte types and red blood cell counts, possibly reflecting responses to parasite types. Among males, we predicted greater investments in spermatogenesis would result in reduced immunological investments. We found a negative association between testes and spleen size and a positive relationship between testes and number of lice suggesting trade-offs in reproductive investment possibly due to the costs associated with spermatogenesis and immunity. We suggest when measuring sexual differences in immunity it is important to consider the effects of reproductive pressures, parasite types, and life history costs

Differential lipid dependence of the function of bacterial sodium channels

The lipid bilayer is important for maintaining the integrity of cellular compartments and plays a vital role in providing the hydrophobic and charged interactions necessary for membrane protein structure, conformational flexibility and function. To directly assess the lipid dependence of activity for voltage-gated sodium channels, we compared the activity of three bacterial sodium channel homologues (NaChBac, NavMs, and NavSp) by cumulative 22Na+ uptake into proteoliposomes containing a 3:1 ratio of 1-palmitoyl 2-oleoyl phosphatidylethanolamine and different “guest” glycerophospholipids. We observed a unique lipid profile for each channel tested. NavMs and NavSp showed strong preference for different negatively-charged lipids (phosphatidylinositol and phosphatidylglycerol, respectively), whilst NaChBac exhibited a more modest variation with lipid type. To investigate the molecular bases of these differences we used synchrotron radiation circular dichroism spectroscopy to compare structures in liposomes of different composition, and molecular modeling and electrostatics calculations to rationalize the functional differences seen. We then examined pore-only constructs (with voltage sensor subdomains removed) and found that in these channels the lipid specificity was drastically reduced, suggesting that the specific lipid influences on voltage-gated sodium channels arise primarily from their abilities to interact with the voltage-sensing subdomains

Direction of Movement Is Encoded in the Human Primary Motor Cortex

The present study investigated how direction of hand movement, which is a well-described parameter in cerebral organization of motor control, is incorporated in the somatotopic representation of the manual effector system in the human primary motor cortex (M1). Using functional magnetic resonance imaging (fMRI) and a manual step-tracking task we found that activation patterns related to movement in different directions were spatially disjoint within the representation area of the hand on M1. Foci of activation related to specific movement directions were segregated within the M1 hand area; activation related to direction 0° (right) was located most laterally/superficially, whereas directions 180° (left) and 270° (down) elicited activation more medially within the hand area. Activation related to direction 90° was located between the other directions. Moreover, by investigating differences between activations related to movement along the horizontal (0°+180°) and vertical (90°+270°) axis, we found that activation related to the horizontal axis was located more anterolaterally/dorsally in M1 than for the vertical axis, supporting that activations related to individual movement directions are direction- and not muscle related. Our results of spatially segregated direction-related activations in M1 are in accordance with findings of recent fMRI studies on neural encoding of direction in human M1. Our results thus provide further evidence for a direct link between direction as an organizational principle in sensorimotor transformation and movement execution coded by effector representations in M1

Double trouble at high density::Cross-level test of ressource-related adaptive plasticity and crowding-related fitness.

Population size is often regulated by negative feedback between population density and individual fitness. At high population densities, animals run into double trouble: they might concurrently suffer from overexploitation of resources and also from negative interference among individuals regardless of resource availability, referred to as crowding. Animals are able to adapt to resource shortages by exhibiting a repertoire of life history and physiological plasticities. In addition to resource-related plasticity, crowding might lead to reduced fitness, with consequences for individual life history. We explored how different mechanisms behind resource-related plasticity and crowding-related fitness act independently or together, using the water flea Daphnia magna as a case study. For testing hypotheses related to mechanisms of plasticity and crowding stress across different biological levels, we used an individual-based population model that is based on dynamic energy budget theory. Each of the hypotheses, represented by a sub-model, is based on specific assumptions on how the uptake and allocation of energy are altered under conditions of resource shortage or crowding. For cross-level testing of different hypotheses, we explored how well the sub-models fit individual level data and also how well they predict population dynamics under different conditions of resource availability. Only operating resource-related and crowding-related hypotheses together enabled accurate model predictions of D. magna population dynamics and size structure. Whereas this study showed that various mechanisms might play a role in the negative feedback between population density and individual life history, it also indicated that different density levels might instigate the onset of the different mechanisms. This study provides an example of how the integration of dynamic energy budget theory and individual-based modelling can facilitate the exploration of mechanisms behind the regulation of population size. Such understanding is important for assessment, management and the conservation of populations and thereby biodiversity in ecosystems

Percutaneous treatment of patients with heart diseases: selection, guidance and follow-up. A review

Aortic stenosis and mitral regurgitation, patent foramen ovale, interatrial septal defect, atrial fibrillation and perivalvular leak, are now amenable to percutaneous treatment. These percutaneous procedures require the use of Transthoracic (TTE), Transesophageal (TEE) and/or Intracardiac echocardiography (ICE). This paper provides an overview of the different percutaneous interventions, trying to provide a systematic and comprehensive approach for selection, guidance and follow-up of patients undergoing these procedures, illustrating the key role of 2D echocardiography