200 research outputs found

    The intensity dependent spread model and color constancy

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    Odetics is investigating the use of the intensity dependent spread (IDS) model for determining color constancy. Object segmentation is performed effortlessly by the human visual systems, but creating computer vision that takes an image as input and performs object identification on the basis of color has some difficulties. The unknown aspects of the light illuminating a scene in space or anywhere can seriously interfere with the use of color for object identification. The color of an image depends not only on the physical characteristics of the object, but also on the wavelength composition of the incident illumination. IDS processing provides the extraction of edges and of reflectance changes across edges, independent of variations in scene illumination. IDS depends solely on the ratio of the reflectances on the two sides of the edge. Researchers are in the process of using IDS to recover the reflectance image

    Threat expert system technology advisor

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    A prototype expert system was developed to determine the feasibility of using expert system technology to enhance the performance and survivability of helicopter pilots in a combat threat environment while flying NOE (Nap of the Earth) missions. The basis for the concept is the potential of using an Expert System Advisor to reduce the extreme overloading of the pilot who flies NOE mission below treetop level at approximately 40 knots while performing several other functions. The ultimate goal is to develop a Threat Expert System Advisor which provides threat information and advice that are better than even a highly experienced copilot. The results clearly show that the NOE pilot needs all the help in decision aiding and threat situation awareness that he can get. It clearly shows that heuristics are important and that an expert system for combat NOE helicopter missions can be of great help to the pilot in complex threat situations and in making decisions

    Developmental and functional relationships between hypothalamic tanycytes and embryonic radial glia

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    The hypothalamus is a key regulator of several homeostatic processes, such as circadian rhythms, energy balance, thirst, and thermoregulation. Recently, the hypothalamic third ventricle has emerged as a site of postnatal neurogenesis and gliogenesis. This hypothalamic neural stem potential resides in a heterogeneous population of cells known as tanycytes, which, not unlike radial glia, line the floor and ventrolateral walls of the third ventricle and extend a long process into the hypothalamic parenchyma. Here, we will review historical and recent data regarding tanycyte biology across the lifespan, focusing on the developmental emergence of these diverse cells from embryonic radial glia and their eventual role contributing to a fascinating, but relatively poorly characterized, adult neural stem cell niche

    Feeding and fasting controls liver expression of a regulator of G protein signaling (Rgs16) in periportal hepatocytes

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    BACKGROUND: Heterotrimeric G protein signaling in liver helps maintain carbohydrate and lipid homeostasis. G protein signaling is activated by binding of extracellular ligands to G protein coupled receptors and inhibited inside cells by regulators of G protein signaling (RGS) proteins. RGS proteins are GTPase activating proteins, and thereby regulate Gi and/or Gq class G proteins. RGS gene expression can be induced by the ligands they feedback regulate, and RGS gene expression can be used to mark tissues and cell-types when and where Gi/q signaling occurs. We characterized the expression of mouse RGS genes in liver during fasting and refeeding to identify novel signaling pathways controlling changes in liver metabolism. RESULTS: Rgs16 is the only RGS gene that is diurnally regulated in liver of ad libitum fed mice. Rgs16 transcription, mRNA and protein are up regulated during fasting and rapidly down regulated after refeeding. Rgs16 is expressed in periportal hepatocytes, the oxygen-rich zone of the liver where lipolysis and gluconeogenesis predominates. Restricting feeding to 4 hr of the light phase entrained Rgs16 expression in liver but did not affect circadian regulation of Rgs16 expression in the suprachiasmatic nuclei (SCN). CONCLUSION: Rgs16 is one of a subset of genes that is circadian regulated both in SCN and liver. Rgs16 mRNA expression in liver responds rapidly to changes in feeding schedule, coincident with key transcription factors controlling the circadian clock. Rgs16 expression can be used as a marker to identify and investigate novel G-protein mediated metabolic and circadian pathways, in specific zones within the liver

    Neuroendocrine transcriptional programs adapt dynamically to the supply and demand for neuropeptides as revealed in NSF mutant zebrafish

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    <p>Abstract</p> <p>Background</p> <p>Regulated secretion of specialized neuropeptides in the vertebrate neuroendocrine system is critical for ensuring physiological homeostasis. Expression of these cell-specific peptide markers in the differentiating hypothalamus commences prior to birth, often predating the physiological demand for secreted neuropeptides. The conserved function and spatial expression of hypothalamic peptides in vertebrates prompted us to search for critical neuroendocrine genes in newly hatched zebrafish larvae.</p> <p>Results</p> <p>We screened mutant 5 days post-fertilization zebrafish larvae that fail to undergo visually mediated background adaptation for disruption in hypothalamic <it>pomc </it>expression. To our surprise, the ATPase <it>N-ethylmaleimide sensitive factor </it>(<it>nsf</it>) was identified as an essential gene for maintenance of neuroendocrine transcriptional programs during the embryo-to-larva transition. Despite normal hypothalamic development in <it>nsf</it><sup><it>st</it>53 </sup>mutants, neuropeptidergic cells exhibited a dramatic loss of cell-specific markers by 5 days post-fertilization that is accompanied by elevated intracellular neuropeptide protein. Consistent with the role of NSF in vesicle-membrane fusion events and intracellular trafficking, cytoplasmic endoplasmic reticulum-like membranes accumulate in <it>nsf</it><sup>-/- </sup>hypothalamic neurons similar to that observed for <it>SEC18 </it>(<it>nsf ortholog</it>) yeast mutants. Our data support a model in which unspent neuropeptide cargo feedbacks to extinguish transcription in neuropeptidergic cells just as they become functionally required. In support of this model we found that <it>gnrh3 </it>transcripts remained unchanged in pre-migratory, non-functional gonadotropin-releasing hormone (GnRH) neurons in <it>nsf</it><sup>-/- </sup>zebrafish. Furthermore, <it>oxytocin-like </it>(<it>oxtl</it>, <it>intp</it>) transcripts, which are found in osmoreceptive neurons and persist in mutant zebrafish, drop precipitously after mutant zebrafish are acutely challenged with high salt.</p> <p>Conclusion</p> <p>Our analyses of <it>nsf </it>mutant zebrafish reveal an unexpected role for NSF in hypothalamic development, with mutant 5 days post-fertilization larvae exhibiting a stage-dependent loss of neuroendocrine transcripts and a corresponding accumulation of neuropeptides in the soma. Based on our collective findings, we speculate that neuroendocrine transcriptional programs adapt dynamically to both the supply and demand for neuropeptides to ensure adequate homeostatic responses.</p

    Safety of Repeated Open-Label Treatment Courses of Intravenous Ofatumumab, a Human Anti-CD20 Monoclonal Antibody, in Rheumatoid Arthritis:Results from Three Clinical Trials

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    OBJECTIVES:To investigate the safety of ofatumumab retreatment in rheumatoid arthritis. METHODS:Patients with active rheumatoid arthritis participating in two phase III trials (OFA110635 and OFA110634) and a phase II extension trial (OFA111752) received individualised open-label ofatumumab retreatment (700 mg X 2 intravenous infusions two weeks apart) ≥24 weeks following the first course and ≥16 weeks following further courses. Retreatment required evidence of clinical response followed by disease relapse. These studies were prematurely terminated by the sponsor to refocus development on subcutaneous delivery. Due to differences in study designs and populations, data are summarised separately for each study. RESULTS:483 patients (243, 148 and 92 in OFA110635, OFA110634 and OFA111752 respectively) received up to 7 treatment courses of intravenous ofatumumab; cumulative duration of exposure was 463, 182 and 175 patient-years, respectively. Mean time between courses was 17-47 weeks. Ofatumumab induced a profound depletion of peripheral B-lymphocytes. Retreated patients derived benefit based on improvement in DAS28. Adverse events were reported for 93% (226/243), 91% (134/148) and 76% (70/92), serious adverse events for 18% (44/243), 20% (30/148) and 12% (11/92) and serious infections for 3% (8/243), 5% (7/148) and 1% (1/92) of patients in OFA110635, OFA110634 and OFA111752, respectively. The most common adverse events were infusion-related reactions during the first infusion of the first course (48-79%); serious infusion-related reactions were rare (<1% [1/243], 5% [8/148], and 1% [1/92] of patients). Two deaths occurred (fulminant hepatitis B virus infection and interstitial lung disease). CONCLUSIONS:Ofatumumab was generally well tolerated with no evidence of increased safety risks with multiple retreatments. Serious infections were uncommon and did not increase over time. TRIAL REGISTRATION:ClinicalTrials.gov 110635 ClinicalTrials.gov 110634 ClinicalTrials.gov 111752

    5-HT2A receptor signalling through phospholipase D1 associated with its C-terminal tail

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    The 5-HT2AR (5-hydroxytryptamine-2A receptor) is a GPCR (G-protein-coupled receptor) that is implicated in the actions of hallucinogens and represents a major target of atypical antipsychotic agents. In addition to its classical signalling though PLC (phospholipase C), the receptor can activate several other pathways, including ARF (ADP-ribosylation factor)-dependent activation of PLD (phospholipase D), which appears to be achieved through a mechanism independent of heterotrimeric G-proteins. In the present study we show that wild-type and inactive constructs of PLD1 (but not PLD2) respectively facilitate and inhibit ARF-dependent PLD signalling by the 5-HT2AR. Furthermore we demonstrate that PLD1 specifically co-immunoprecipitates with the receptor and binds to a distal site in GST (glutathione transferase) fusion protein constructs of its C-terminal tail which is distinct from the ARF-interaction site, thereby suggesting the existence of a functional ARF-PLD signalling complex directly associated with this receptor. This reveals the spatial co-ordination of an important GPCR, transducer and effector into a physical complex that is likely to reinforce the impact of receptor activation on a heterotrimeric G-protein-independent signalling pathway. Signalling of this receptor through such non-canonical pathways may be important to its role in particular disorders

    Epicardial cell shape and maturation are regulated by Wt1 via transcriptional control of Bmp4

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    The epicardium plays a crucial role in embryonic heart development and adult heart repair; however, the molecular events underlying its maturation remain unknown. Wt1, one of the main markers of the embryonic epicardium, is essential for epicardial development and function. Here, we analyse the transcriptomic profile of epicardial-enriched cells at different stages of development and from control and epicardial-specific Wt1 knockout (Wt1KO) mice. Transcriptomic and cell morphology analyses of epicardial cells from epicardial-specific Wt1KO mice revealed a defect in the maturation process of the mutant epicardium, including sustained upregulation of Bmp4 expression and the inability of mutant epicardial cells to transition into a mature squamous phenotype. We identified Bmp4 as a transcriptional target of Wt1, thus providing a molecular basis for the retention of the cuboidal cell shape observed in the Wt1KO epicardium. Accordingly, inhibition of the Bmp4 signalling pathway both ex vivo and in vivo rescued the cuboidal phenotype of the mutant epicardium. Our findings indicate the importance of the cuboidal-to-squamous transition in epicardial maturation, a process regulated by Wt1

    The effect of 24-week belimumab treatment withdrawal followed by treatment restart in patients with SLE: an open-label, non-randomised 52-week study

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    Abstract Background Treatment goals for patients with systemic lupus erythematosus (SLE) include minimising disease activity and reducing the risk of flares. Although belimumab is effective at reducing disease activity and risk of severe flares, it was previously unknown what the clinical effects were upon treatment discontinuation. The objective of this study was to assess the impact of temporary withdrawal of intravenous (IV) belimumab in patients with SLE. Methods This multicentre, open-label, non-randomised, 52-week study (GSK Study BEL116027; NCT02119156) recruited patients with SLE and stable low disease activity, of whom those on belimumab 10 mg/kg IV plus standard therapy either discontinued belimumab for 24 weeks and then restarted belimumab 10 mg/kg IV every 4 weeks (q4w) for 28 weeks (treatment holiday [TH] group), or continued on belimumab 10 mg/kg IV plus standard therapy q4w for 52 weeks (treatment continuation [TC] group). The primary endpoint was median time to first Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) Flare Index flare. Secondary and other endpoints included rate of any flare, time to severe flare, time to renal flare and rebound (SELENA-SLEDAI score exceeding parent study baseline). Data on rebound phenomenon in patients with any disease level of SLE who had permanently withdrawn from further belimumab treatment (long-term discontinuation group [LTD]) were also assessed. Safety was assessed. Results The primary endpoint was not evaluable in the TH (n = 12) and TC (n = 29) groups as fewer than half of patients flared. Unadjusted flare rates per patient-year were 1.0 during treatment discontinuation and 0.3 during treatment restart (0.6 overall) in the TH group and 0.6 in the TC group; there were no severe or renal flares. No TH patients rebounded; 2 (6.9%) TC patients rebounded; 2 (5.1%) patients in the LTD group rebounded. There were no new safety signals. Conclusions Twenty-four-week belimumab discontinuation did not appear to increase the risk of flares or rebound in patients with low SLE disease activity; flare rates were low in both groups. Further studies may help to fully determine the effect of belimumab discontinuation. Trial registration ClinicalTrials.gov, NCT02119156 . Registered on April 21, 2014
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