987 research outputs found

    The Relation Between Magnetospheric State Parameters and the Occurrence of Plasma Depletion Events in the Night-Time Mid-Latitude F-Region

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    Studies using all-sky imagers have revealed the presence of various ionospheric irregularities in the night-time mid-latitude F-region. The most prevalent and well known of these are the Medium Scale Traveling Ionospheric Disturbances (MSTIDs) that usually occur when the geomagnetic activity is low, and mid-latitude spread-F plumes that are often observed when the geomagnetic activity is high. The inverse and direct relations between geomagnetic activity (particularly Kp) and the occurrence rate of MSTIDs and midlatitude plumes, respectively, have been observed by several studies using different instruments. In order to understand the underlying causes of these two relations, it is illuminating to better characterize the occurrence of MSTIDs and plumes using multiple magnetospheric state parameters. Here we statistically compare multiple geomagnetic driver and response parameters (such as Kp, AE, Dst, and solar wind parameters) with the occurrence rates of night-time MSTIDs and plumes observed using an all-sky imager at Arecibo Observatory (AO) between 2003 and 2008. The results not only allow us to better distinguish MSTIDs and plumes, but also shed further light on the generation mechanism and electrodynamics of these two different phenomena occurring at night-time in the mid-latitude F-region

    Respiratory burst function of ovine neutrophils

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    Background: Respiratory burst function resulting in the release of reactive oxygen species such as superoxide anion (O(2)(-)) from neutrophils is one of the key mechanisms of the innate immune system, and maladaptive control of this mechanism is thought to play a pivotal role in the development of pathologies such as acute lung injury and sepsis. Ovine models of these pathologies are limited by the poor understanding of ovine neutrophil respiratory burst function

    Convergence of TOR-nitrogen and Snf1-glucose signaling pathways onto Gln3

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    Carbon and nitrogen are two basic nutrient sources for cellular organisms. They supply precursors for energy metabolism and metabolic biosynthesis. In the yeast Saccharomyces cerevisiae, distinct sensing and signaling pathways have been described that regulate gene expression in response to the quality of carbon and nitrogen sources, respectively. Gln3 is a GATA-type transcription factor of nitrogen catabolite-repressible (NCR) genes. Previous observations indicate that the quality of nitrogen sources controls the phosphorylation and cytoplasmic retention of Gln3 via the target of rapamycin (TOR) protein. In this study, we show that glucose also regulates Gln3 phosphorylation and subcellular localization, which is mediated by Snf1, the yeast homolog of AMP-dependent protein kinase and a cytoplasmic glucose sensor. Our data show that glucose and nitrogen signaling pathways converge onto Gln3, which may be critical for both nutrient sensing and starvation responses

    The impact of acute lung injury, ECMO and transfusion on oxidative stress and plasma selenium levels in an ovine model

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    The purpose of this study was to determine the effects of smoke induced acute lung. injury (S-ALI), extracorporeal membrane oxygenation (ECMO) and transfusion on oxidative stress and plasma selenium levels. Forty ewes were divided into (i) healthy control (n = 4), (ii) S-ALI control (n = 7), (iii) ECMO control (n = 7), (iv) S-ALI + ECMO (n = 8) and (v) S-ALI + ECM + packed red blood cell (PRBC) transfusion (n = 14). Plasma thiobarbituric acid reactive substances (TBARS), selenium and glutathione peroxidase (GPx) activity were analysed at baseline, after smoke injury (or sham) and 0.25, 1, 2, 6, 7, 12 and 24 h after initiation of ECMO. Peak TBARS levels were similar across all groups. Plasma selenium decreased by 54% in S-ALI sheep (1.36 +/- 0.20 to 0.63 +/- 0.27 mu mol/L, p < 0.0001), and 72% in sheep with S-ALI + ECMO at 24 h (1.36 +/- 0.20 to 0.38 +/- 0.19, p < 0.0001). PRBC transfusion had no effect on TBARS, selenium levels or glutathione peroxidase activity in plasma. While ECMO independently increased TBARS in healthy sheep to levels which were similar to the S-ALI control, the addition of ECMO after S-ALI caused a negligible increase in TBARS. This suggests that the initial lung injury was the predominant feature in the TBARS response. In contrast, the addition of ECM in S-ALI sheep exacerbated reductions in plasma selenium beyond that of S-ALI or ECM alone. Clinical studies are needed to confirm the extent and duration of selenium loss associated with ECMO. Crown Copyright (C) 2015 Published by Elsevier GmbH. All rights reserved

    Mutational analysis of head and neck squamous cell carcinoma stratified by smoking status.

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    Smoking has historically been recognized as a negative prognostic factor in head and neck squamous cell carcinoma (HNSCC). This study aimed to assess the mutational differences between heavy smokers (\u3e20 pack years) and never smokers among the HNSCC patients within The Cancer Genome Atlas (TCGA). Single nucleotide variation and copy number aberration differences between heavy smokers and never smokers were compared within human papillomavirus-positive (HPV-positive) (n = 67) and HPV-negative (n = 431) TCGA cohorts with HNSCC, and the impact of these mutations on survival were assessed. No genes were differentially mutated between smoking and never-smoking patients with HPV-positive tumors. By contrast, in HPV-negative tumors, NSD1 and COL1A11 were found to be more frequently mutated in heavy smokers, while CASP8 was more frequently altered in never smokers. HPV-negative patients with NSD1 mutations experienced significantly improved overall survival compared with NSD1 WT patients. This improved prognosis was validated in an independent cohort of 77 oral cavity cancer patients and a meta-analysis that included 2 additional data sets (688 total patients, hazard ratio for death 0.44, 95% CI, 0.30-0.65). NSD1 mutations are more common in HPV-negative heavy smokers, define a cohort with favorable prognosis, and may represent a clinically useful biomarker to guide treatment deintensification for HPV-negative patients

    A Large Population Histology Study Showing the Lack of Association between ALT Elevation and Significant Fibrosis in Chronic Hepatitis B

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    OBJECTIVE: We determined the association between various clinical parameters and significant liver injury in both hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients. METHODS: From 1994 to 2008, liver biopsy was performed on 319 treatment-naive CHB patients. Histologic assessment was based on the Knodell histologic activity index for necroinflammation and the Ishak fibrosis staging for fibrosis. RESULTS: 211 HBeAg-positive and 108 HBeAg-negative patients were recruited, with a median age of 31 and 46 years respectively. 9 out of 40 (22.5%) HBeAg-positive patients with normal ALT had significant histologic abnormalities (necroinflammation grading >/= 7 or fibrosis score >/= 3). There was a significant difference in fibrosis scores among HBeAg-positive patients with an ALT level within the Prati criteria (30 U/L for men, 19 U/L for women) and patients with a normal ALT but exceeding the Prati criteria (p = 0.024). Age, aspartate aminotransferase and platelet count were independent predictors of significant fibrosis in HBeAg-positive patients with an elevated ALT by multivariate analysis (p = 0.007, 0.047 and 0.045 respectively). HBV DNA and platelet count were predictors of significant fibrosis in HBeAg-negative disease (p = 0.020 and 0.015 respectively). An elevated ALT was not predictive of significant fibrosis for HBeAg-positive (p = 0.345) and -negative (p = 0.544) disease. There was no significant difference in fibrosis staging among ALT 1-2 x upper limit of normal (ULN) and > x 2 ULN for both HBeAg-positive (p = 0.098) and -negative (p = 0.838) disease. CONCLUSION: An elevated ALT does not accurately predict significant liver injury. Decisions on commencing antiviral therapy should not be heavily based on a particular ALT threshold.published_or_final_versio

    Risk factors for postoperative complications after adrenalectomy for phaeochromocytoma: multicentre cohort study

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    Background: To determine the incidence and risk factors for postoperative complications and prolonged hospital stay after adrenalectomy for phaeochromocytoma. Methods: Demographics, perioperative outcomes and complications were evaluated for consecutive patients who underwent adrenalectomy for phaeochromocytoma from 2012 to 2020 in nine high-volume UK centres. Odds ratios were calculated using multivariable models. The primary outcome was postoperative complications according to the Clavien–­­Dindo classification and secondary outcome was duration of hospital stay. Results: Data were available for 406 patients (female n = 221, 54.4 per cent). Two patients (0.5 per cent) had perioperative death, whilst 148 complications were recorded in 109 (26.8 per cent) patients. On adjusted analysis, the age-adjusted Charlson Co-morbidity Index ≥3 (OR 8.09, 95 per cent c.i. 2.31 to 29.63, P = 0.001), laparoscopic converted to open (OR 10.34, 95 per cent c.i. 3.24 to 36.23,
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