78 research outputs found
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Uncertainties in steric sea level change estimation during the satellite altimeter era: concepts and practices
This article presents a review of current practice in estimating steric sea level change, focussed on the treatment of uncertainty. Steric sea level change is the contribution to the change in sea level arising from the dependence of density on temperature and salinity. It is a significant component of sea level rise and a reflection of changing ocean heat content. However tracking these steric changes remains still a significant challenge for the scientific community. We review the importance of understanding the uncertainty in estimates of steric sea level change. Relevant concepts of uncertainty are discussed and illustrated with the example of observational uncertainty propagation from a single profile of temperature and salinity measurements to steric height. We summarise and discuss the recent literature on methodologies and techniques used to estimate steric sea level in the context of the treatment of uncertainty. Our conclusions are that progress in quantifying steric sea level uncertainty will benefit from: greater clarity and transparency in published discussions of uncertainty, including exploitation of international standards for quantifying and expressing uncertainty in measurement; and the development of community ‘recipes’ for quantifying the error covariances in observations and from sparse sampling, and for estimating and propagating uncertainty across spatio-temporal scales
Phosphodiesterase Inhibition Increases CREB Phosphorylation and Restores Orientation Selectivity in a Model of Fetal Alcohol Spectrum Disorders
Background: Fetal alcohol spectrum disorders (FASD) are the leading cause of mental retardation in the western world and children with FASD present altered somatosensory, auditory and visual processing. There is growing evidence that some of these sensory processing problems may be related to altered cortical maps caused by impaired developmental neuronal plasticity. Methodology/Principal Findings: Here we show that the primary visual cortex of ferrets exposed to alcohol during the third trimester equivalent of human gestation have decreased CREB phosphorylation and poor orientation selectivity revealed by western blotting, optical imaging of intrinsic signals and single-unit extracellular recording techniques. Treating animals several days after the period of alcohol exposure with a phosphodiesterase type 1 inhibitor (Vinpocetine) increased CREB phosphorylation and restored orientation selectivity columns and neuronal orientation tuning. Conclusions/Significance: These findings suggest that CREB function is important for the maturation of orientation selectivity and that plasticity enhancement by vinpocetine may play a role in the treatment of sensory problems in FASD
Neocortical Axon Arbors Trade-off Material and Conduction Delay Conservation
The brain contains a complex network of axons rapidly communicating information between billions of synaptically connected neurons. The morphology of individual axons, therefore, defines the course of information flow within the brain. More than a century ago, Ramón y Cajal proposed that conservation laws to save material (wire) length and limit conduction delay regulate the design of individual axon arbors in cerebral cortex. Yet the spatial and temporal communication costs of single neocortical axons remain undefined. Here, using reconstructions of in vivo labelled excitatory spiny cell and inhibitory basket cell intracortical axons combined with a variety of graph optimization algorithms, we empirically investigated Cajal's conservation laws in cerebral cortex for whole three-dimensional (3D) axon arbors, to our knowledge the first study of its kind. We found intracortical axons were significantly longer than optimal. The temporal cost of cortical axons was also suboptimal though far superior to wire-minimized arbors. We discovered that cortical axon branching appears to promote a low temporal dispersion of axonal latencies and a tight relationship between cortical distance and axonal latency. In addition, inhibitory basket cell axonal latencies may occur within a much narrower temporal window than excitatory spiny cell axons, which may help boost signal detection. Thus, to optimize neuronal network communication we find that a modest excess of axonal wire is traded-off to enhance arbor temporal economy and precision. Our results offer insight into the principles of brain organization and communication in and development of grey matter, where temporal precision is a crucial prerequisite for coincidence detection, synchronization and rapid network oscillations
Eosinophils in glioblastoma biology
Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The development of this malignant glial lesion involves a multi-faceted process that results in a loss of genetic or epigenetic gene control, un-regulated cell growth, and immune tolerance. Of interest, atopic diseases are characterized by a lack of immune tolerance and are inversely associated with glioma risk. One cell type that is an established effector cell in the pathobiology of atopic disease is the eosinophil. In response to various stimuli, the eosinophil is able to produce cytotoxic granules, neuromediators, and pro-inflammatory cytokines as well as pro-fibrotic and angiogenic factors involved in pathogen clearance and tissue remodeling and repair. These various biological properties reveal that the eosinophil is a key immunoregulatory cell capable of influencing the activity of both innate and adaptive immune responses. Of central importance to this report is the observation that eosinophil migration to the brain occurs in response to traumatic brain injury and following certain immunotherapeutic treatments for GBM. Although eosinophils have been identified in various central nervous system pathologies, and are known to operate in wound/repair and tumorstatic models, the potential roles of eosinophils in GBM development and the tumor immunological response are only beginning to be recognized and are therefore the subject of the present review
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Prolonged Profound Hypoxia and Cardiac Failure in a Young Woman Presenting to the Emergency Department: Unexpected Pulmonary Embolus, Catheter-Directed Thrombolysis, and Subsequent Multi-Organ Failure
Pulmonary emboli are rare occurrences in young patients, especially those who present precipitously to the emergency department. In a young unresponsive patient, recognition of thromboembolic etiology may be delayed due to atypical presenting physiology or competing diagnoses. In this report, the authors describe an initially confounding case of catastrophic bilateral pulmonary emboli in a young woman who presented to the emergency department having been found unconscious on the street. Despite severe and prolonged hypoxia as well as multi-organ failure, the patient achieved a near complete recovery. © 2012 The Author(s)
Fever of unknown origin: large vessel vasculitis diagnosed by PET/CT
PET/CT is starting to play an important role in evaluating fever of unknown origin (FUO), due to its ability to localize and delineate areas of high metabolic activity, such as neoplastic proliferation and inflammation, including vasculitis. We present a case of giant cell arteritis (GCA) in a 72-year-old female patient admitted to our department with a 4-month history of FUO, weight loss and fatigue, without specific symptoms or signs. Laboratory investigations suggested acute phase response, with a pronounced erythrocyte sedimentation rate, high CRP level and microcytic anemia. A thorough diagnostic evaluation was performed to exclude an unknown primary tumor, which was initially suspected due to a positive family history of cancer. Surprisingly, PET/CT revealed large vessel vasculitis affecting the ascending, descending and abdominal aorta, as well as subclavian, proximal brachial and carotid arteries bilaterally. Biopsy of the superficial temporal artery confirmed the diagnosis of GCA. Treatment with methylprednisolone and azathioprine led to resolution of clinical symptoms and normalization of laboratory parameters. In addition to the use of PET/CT in the evaluation of FUO, its value as a method complementary to temporal artery biopsy is also discussed
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