8,997 research outputs found

    Distribution of hydrogen peroxide and methylhydroperoxide over the Pacific and South Atlantic Oceans

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    The gas phase hydrogen peroxide and methylhydroperoxide concentrations were measured in the troposphere over the tropical Pacific Ocean as a component of NASA's Global Tropospheric Experiment/Pacific Exploratory Mission-Tropics A field campaign. Flights on two aircraft covered the Pacific from 70°S to 60°N and 110°E to 80°W and South Atlantic from 40°S to 15°N and 45°W to 70°E, and extending from 76 to 13,000 m altitude. H2O2 and CH3OOH have the highest concentrations at a given altitude at the equator and decrease with increasing latitude in both the northern and southern hemispheres. Above 4 km the gradient is substantially reduced for both H2O2 and CH3OOH with latitude, and at altitudes in excess of 8 km there is no latitudinal dependence. H2O2 and CH3OOH exhibit maximum mixing ratios between 1 and 2 km at all latitudes. The mean mixing ratio of H2O2 at the equator was 1600 ± 600 parts per trillion by volume (pptv) decreasing to 500 ± 250 pptv at latitudes greater than 55° north and south between 1 and 2 km altitude. CH3OOH at the equator was 1400 ± 250 pptv, decreasing to 330 ± 200 pptv at high latitudes at altitudes between 1 and 2 km. The concentration of peroxides at high latitudes in the northern hemisphere was generally a factor of 2 higher than at corresponding latitudes in the southern hemisphere. The ratio of H2O2 to CH3OOH was between 1 and 2 from 45°S to 35°N at altitudes below 4 km. Between 5° to 15°N the ratio is less than 1, due to preferential removal of H2O2 in the Intertropical Convergence Zone. Copyright 1999 by the American Geophysical Union

    Bacterial Infection Elicits Heat Shock Protein 72 Release from Pleural Mesothelial Cells

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    Heat shock protein 70 (HSP70) has been implicated in infection-related processes and has been found in body fluids during infection. This study aimed to determine whether pleural mesothelial cells release HSP70 in response to bacterial infection in vitro and in mouse models of serosal infection. In addition, the in vitro cytokine effects of the HSP70 isoform, Hsp72, on mesothelial cells were examined. Further, Hsp72 was measured in human pleural effusions and levels compared between non-infectious and infectious patients to determine the diagnostic accuracy of pleural fluid Hsp72 compared to traditional pleural fluid parameters. We showed that mesothelial release of Hsp72 was significantly raised when cells were treated with live and heat-killed Streptococcus pneumoniae. In mice, intraperitoneal injection of S. pneumoniae stimulated a 2-fold increase in Hsp72 levels in peritoneal lavage (p<0.01). Extracellular Hsp72 did not induce or inhibit mediator release from cultured mesothelial cells. Hsp72 levels were significantly higher in effusions of infectious origin compared to non-infectious effusions (p<0.05). The data establish that pleural mesothelial cells can release Hsp72 in response to bacterial infection and levels are raised in infectious pleural effusions. The biological role of HSP70 in pleural infection warrants exploration

    Adapting tissue-engineered in vitro CNS models for high-throughput study of neurodegeneration

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    Neurodegenerative conditions remain difficult to treat, with the continuing failure to see therapeutic research successfully advance to clinical trials. One of the obstacles that must be overcome is to develop enhanced models of disease. Tissue engineering techniques enable us to create organised artificial central nervous system tissue that has the potential to improve the drug development process. This study presents a replicable model of neurodegenerative pathology through the use of engineered neural tissue co-cultures that can incorporate cells from various sources and allow degeneration and protection of neurons to be observed easily and measured, following exposure to neurotoxic compounds - okadaic acid and 1-methyl-4-phenylpyridinium. Furthermore, the technology has been miniaturised through development of a mould with 6 mm length that recreates the advantageous features of engineered neural tissue co-cultures at a scale suitable for commercial research and development. Integration of human-derived induced pluripotent stem cells aids more accurate modelling of human diseases, creating new possibilities for engineered neural tissue co-cultures and their use in drug screening

    TLR9 regulates adipose tissue inflammation and obesity-related metabolic disorders

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    ObjectiveRecent studies have revealed a link between Toll-like receptor (TLR) signaling and the adipose tissue inflammation associated with obesity. Although TLR9 is known to play an important role in inflammation and innate immunity, its role in mediating adipose tissue inflammation has not yet been investigated. Thus, the objective of this study was to determine the role of TLR9 in regulating immune cells in visceral adipose tissue and maintaining the metabolic homeostasis. MethodsWild-type and TLR9-deficient mice were fed with a high-fat diet, and the body weight gain, glucose tolerance, insulin sensitivity, and adipose tissue inflammation were examined. ResultsTLR9-deficient mice gained significantly more weight and body fat under a high-fat diet than wild-type mice and exhibited more severe glucose intolerance and insulin resistance. We also found a dramatic increase of M1 macrophages as well as T(H)1 cells in the adipose tissue of TLR9-deficient mice compared to wild-type mice. Furthermore, the levels of various proinflammatory cytokines and chemokines were higher in TLR9-deficient mice. ConclusionsTLR9 signaling is involved in regulating adipose tissue inflammation and controlling obesity and the metabolic syndrome.1174Ysciescopu

    Empirical likelihood estimation of the spatial quantile regression

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    The spatial quantile regression model is a useful and flexible model for analysis of empirical problems with spatial dimension. This paper introduces an alternative estimator for this model. The properties of the proposed estimator are discussed in a comparative perspective with regard to the other available estimators. Simulation evidence on the small sample properties of the proposed estimator is provided. The proposed estimator is feasible and preferable when the model contains multiple spatial weighting matrices. Furthermore, a version of the proposed estimator based on the exponentially tilted empirical likelihood could be beneficial if model misspecification is suspect

    On instantons as Kaluza-Klein modes of M5-branes

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    Instantons and W-bosons in 5d maximally supersymmetric Yang-Mills theory arise from a circle compactification of the 6d (2,0) theory as Kaluza-Klein modes and winding self-dual strings, respectively. We study an index which counts BPS instantons with electric charges in Coulomb and symmetric phases. We first prove the existence of unique threshold bound state of (noncommutative) U(1) instantons for any instanton number, and also show that charged instantons in the Coulomb phase correctly give the degeneracy of SU(2) self-dual strings. By studying SU(N) self-dual strings in the Coulomb phase, we find novel momentum-carrying degrees on the worldsheet. The total number of these degrees equals the anomaly coefficient of SU(N) (2,0) theory. We finally show that our index can be used to study the symmetric phase of this theory, and provide an interpretation as the superconformal index of the sigma model on instanton moduli space.Comment: 54 pages, 2 figures. v2: references added, figure improved, added comments on self-dual string anomaly, added new materials on the symmetric phase index, other minor correction
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