5,797 research outputs found
Oxygen-covered tungsten crystal shape: time effects, equilibrium, surface energy and the edge-rounding temperature
The equilibrium crystal shape (ECS) of oxygen-covered tungsten micricrystal
is studied as a function of temperature. The specially designed ultrafast
crystal quenching setup with the cooling rate of 6000 K/s allows to draw
conclusions about ECS at high temperatures. The edge-rounding transition is
shown to occur between 1300 K and 1430 K. The ratio of surface free energies
is determined as a function of temperature.Comment: 8 pages, 10 figures, submitted for publicatio
Outcomes and characteristics of ertapenem-nonsusceptible Klebsiella pneumoniae bacteremia at a university hospital in Northern Taiwan: AÂ matched case-control study
Background and purposeCarbapenem-resistant Klebsiella pneumoniae is an emerging problem worldwide. The object of this study was to investigate the risk factors, characteristics and outcomes of ertapenem-nonsusceptible K pneumoniae (ENSKp) bacteremia.MethodsWe conducted a 1:2 ratio matched case-control study. The controls were randomly selected among patients with ertapenem-susceptible K pneumoniae (ESKp) bacteremia and were matched with ENSKp cases for bacteremia.ResultsSeventy-five patients were included in this study (25 cases and 50 controls). Bivariate analysis showed that prior exposure to either ÎČ-Lactam/ÎČ-Lactam-lactamase inhibitors (p = 0.008) or 4th generation cephalosporins (p < 0.001), chronic obstructive pulmonary disease (COPD) (p = 0.001), acute renal failure (p = 0.021), chronic kidney disease without dialysis (p = 0.021), recent hospital stay (p = 0.016), intensive care unit stay (p = 0.002), mechanical ventilation (p = 0.003), central venous catheter placement (p = 0.016), Foley indwelling (p = 0.022), polymicrobial bacteremia (p = 0.003) and higher Pittsburgh bacteremia score (p < 0.001) were associated with ENSKp bacteremia. The multivariate analysis showed that prior exposure to 4th generation cephalosporins (odds ratio [OR], 28.05; 95% confidence interval [CI], 2.92â269.85; p = 0.004), COPD (OR, 21.38; 95% CI, 2.95â154.92; p = 0.002) and higher Pittsburgh bacteremia score (OR, 1.35; 95% CI, 1.10â1.66; p = 0.004) were independent factors for ENSKp bacteremia. ENSKp bacteremia had a higher 14-day mortality rate than ESKp bacteremia (44.0% vs. 22.0%; p = 0.049). The overall in-hospital mortality rates for these two groups were 60.0% and 40.0% respectively (p = 0.102).ConclusionENSKp bacteremia had a poor outcome and the risk factors were prior exposure of 4th generation cephalosporins, COPD and higher Pittsburgh bacteremia score. Antibiotic stewardship may be the solution for the preventive strategy
Dosage Compensation of the X Chromosomes in Bovine Germline, Early Embryos, and Somatic Tissues
Dosage compensation of the mammalian X chromosome (X) was proposed by Susumu Ohno as a mechanism wherein the inactivation of one X in females would lead to doubling the expression of the other. This would resolve the dosage imbalance between eutherian females (XX) versus male (XY) and between a single active X versus autosome pairs (A). Expression ratio of X- and A-linked genes has been relatively well studied in humans and mice, despite controversial results over the existence of upregulation of X-linked genes. Here we report the first comprehensive test of Ohnoâs hypothesis in bovine preattachment embryos, germline, and somatic tissues. Overall an incomplete dosage compensation (0.5â\u3câX:Aâ\u3câ1) of expressed genes and an excess X dosage compensation (X:Aâ\u3eâ1) of ubiquitously expressed âdosage-sensitiveâ genes were seen. No significant differences in X:A ratios were observed between bovine female and male somatic tissues, further supporting Ohnoâs hypothesis. Interestingly, preimplantation embryos manifested a unique pattern of X dosage compensation dynamics. Specifically, X dosage decreased after fertilization, indicating that the sperm brings in an inactive X to the matured oocyte. Subsequently, the activation of the bovine embryonic genome enhanced expression of X-linked genes and increased the X dosage. As a result, an excess compensation was exhibited from the 8-cell stage to the compact morula stage. The X dosage peaked at the 16-cell stage and stabilized after the blastocyst stage. Together, our findings confirm Ohnoâs hypothesis of X dosage compensation in the bovine and extend it by showing incomplete and over-compensation for expressed and âdosage-sensitiveâ genes, respectively
Recombinant interleukin-1ÎČ dilates steelhead trout coronary microvessels : effect of temperature and role of the endothelium, nitric oxide and prostaglandins
© 2015. Published by The Company of Biologists Ltd. Acknowledgements We thank Wenjuan Xu and Xin Xu (Hein Lab) for their excellent instruction in microvessel techniques, Dr David Heeley (Biochemistry Department, MUN) for assistance with selecting an appropriate (non-vasoactive) protein stabilizer, Dr Zou (SFIRC, Aberdeen) for advice with regards to the use of rIL-1ÎČ and Gordon Nash (Gamperl Lab) for his assistance with the rIL-1ÎČ purification protocol. Funding This research was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant [RGPIN249926] and Accelerator Supplement [RGPAS412325-2011] to A.K.G. a National Institutes of Health Grant [EY018420] to T.W.H., and a doctoral fellowship from FundaçaÌ o para a CiĂȘncia e a Tecnologia, Portugal [SFRH/BD/27497/2006] to I.A.S.F.C. Deposited in PMC for release after 12 months.Peer reviewedPublisher PD
Simple non-invasive scoring systems and histological scores in predicting mortality in patients with non-alcoholic fatty liver disease: A systematic review and meta-analysis
[Background and Aim] There is debate among the hepatology community regarding the simple non-invasive scoring systems and histological scores (even it was developed for histological classification) in predicting clinical outcomes in patients with non-alcoholic fatty liver disease (NAFLD). This study aimed to determine whether the presence of simple non-invasive scoring systems and histological scores could predict all-cause mortality, liver-related mortality, and liver disease decompensation (liver failure, cirrhosis, hepatocellular carcinoma, or decompensated liver disease).[Methods] The pooled hazard ratio of prognostic factors and incidence rate per 1000 person-years in patients with NAFLD was calculated and further adjusted by two different models of handling the duplicated data.[Results] A total of 19 longitudinal studies were included. Most simple non-invasive scoring systems (Fibrosis-4 Score, BARD, and aspartate aminotransferase-to-platelet ratio index ) and histological scores (NAFLD activity score, Brunt, and "steatosis, activity, and fibrosis" ) failed in predicting mortality, and only the NAFLD fibrosis score > 0.676 showed prognostic ability to all-cause mortality (four studies, 7564 patients, 118 352 person-years followed up, pooled hazard ratio 1.44, 95% confidence interval [CI] 1.05â1.96). The incidence rate per 1000 person-years of all-cause mortality, liver-related mortality, cardiovascular-related mortality, and liver disease decompensation resulted in a pooled incidence rate per 1000 person-years of 22.65 (14 studies, 95% CI 9.62â53.31), 3.19 (7 studies, 95% CI 1.14â8.93), 6.02 (6 studies, 95% CI 4.69â7.74), and 11.46 (4 studies, 95% CI 5.33â24.63), respectively.[Conclusion] Non-alcoholic fatty liver disease fibrosis score showed promising prognostic value to all-cause mortality. Most present simple non-invasive scoring systems and histological scores failed to predict clinical outcomes.Peer reviewe
Phenanthrene-Based Tylophorine-1 (PBT-1) Inhibits Lung Cancer Cell Growth through the Akt and NF-ÎșB Pathways
Tylophorine and related natural compounds exhibit potent antitumor activities. We previously showed that PBT-1, a synthetic C9-substituted phenanthrene-based tylophorine (PBT) derivative, significantly inhibits growth of various cancer cells. In this study, we further explored the mechanisms and potential of PBT-1 as an anticancer agent. PBT-1 dose-dependently suppressed colony formation, induced cell cycle G2/M arrest and apoptosis. DNA microarray and pathway analysis showed that PBT-1 activated the apoptosis pathway and mitogen-activated protein kinase signaling. In contrast, PBT-1 suppressed the nuclear factor kappaB (NF-ÎșB) pathway and focal adhesion. We further confirmed that PBT-1 suppressed Akt activation accelerated RelA degradation via IÎșB kinase-α, and downregulated NF-ÎșB target gene expression. The reciprocal recruitment of RelA and RelB on COX-2 promoter region led to downregulation of transcriptional activity. We conclude that PBT-1 induces cell cycle G2/M arrest and apoptosis by inactivating Akt and by inhibiting the NF-ÎșB signaling pathway. PBT-1 may be a good drug candidate for anticancer chemotherapy
PSR J1926-0652: A Pulsar with Interesting Emission Properties Discovered at FAST
We describe PSR J1926-0652, a pulsar recently discovered with the
Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive
single-pulse detections from FAST and long-term timing observations from the
Parkes 64-m radio telescope, we probed phenomena on both long and short time
scales. The FAST observations covered a wide frequency range from 270 to 800
MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at
least four profile components, short-term nulling lasting from 4 to 450 pulses,
complex subpulse drifting behaviours and intermittency on scales of tens of
minutes. While the average band spacing P3 is relatively constant across
different bursts and components, significant variations in the separation of
adjacent bands are seen, especially near the beginning and end of a burst. Band
shapes and slopes are quite variable, especially for the trailing components
and for the shorter bursts. We show that for each burst the last detectable
pulse prior to emission ceasing has different properties compared to other
pulses. These complexities pose challenges for the classic carousel-type
models.Comment: 13pages with 12 figure
Total synthesis of plagiochin G and derivatives as potential cancer chemopreventive agents
A new and efficient total synthesis has been developed to obtain plagiochin G (22), a macrocyclic bisbibenzyl, and four derivatives. The key 16-membered ring containing biphenyl ether and biaryl units was closed via an intramolecular SNAr reaction. All synthesized macrocyclic bisbibenzyls inhibited Epstein-Barr virus early antigen (EBVEA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells and, thus, are potential cancer chemopreventive agents
Cross-Platform Comparison of Microarray-Based Multiple-Class Prediction
High-throughput microarray technology has been widely applied in biological and medical decision-making research during the past decade. However, the diversity of platforms has made it a challenge to re-use and/or integrate datasets generated in different experiments or labs for constructing array-based diagnostic models. Using large toxicogenomics datasets generated using both Affymetrix and Agilent microarray platforms, we carried out a benchmark evaluation of cross-platform consistency in multiple-class prediction using three widely-used machine learning algorithms. After an initial assessment of model performance on different platforms, we evaluated whether predictive signature features selected in one platform could be directly used to train a model in the other platform and whether predictive models trained using data from one platform could predict datasets profiled using the other platform with comparable performance. Our results established that it is possible to successfully apply multiple-class prediction models across different commercial microarray platforms, offering a number of important benefits such as accelerating the possible translation of biomarkers identified with microarrays to clinically-validated assays. However, this investigation focuses on a technical platform comparison and is actually only the beginning of exploring cross-platform consistency. Further studies are needed to confirm the feasibility of microarray-based cross-platform prediction, especially using independent datasets
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