143 research outputs found
Accretion spin-up and a strong magnetic field in the slow-spinning Be X-ray binary MAXI J0655-013
We present MAXI and NuSTAR observations of the Be X-ray binary, MAXI
J0655-013, in outburst. NuSTAR observed the source once early in the outburst,
when spectral analysis yields a bolometric (0.1--100 keV), unabsorbed source
luminosity of , and a
second time 54 days later, by which time the luminosity dropped to
after first undergoing
a dramatic increase. Timing analysis of the NuSTAR data reveals a neutron star
spin period of s during the first observation, which decreased
to s by the time of the second observation, indicating spin-up due
to accretion throughout the outburst. Furthermore, during the first NuSTAR
observation, we observed quasiperiodic oscillations with centroid frequency
mHz, which exhibited a second harmonic feature. By combining the
MAXI and NuSTAR data with pulse period measurements reported by Fermi/GBM, we
are able to show that apparent flaring behavior in the MAXI light-curve is an
artifact introduced by uneven sampling of the pulse profile, which has a large
pulsed fraction. Finally, we estimate the magnetic field strength at the
neutron star surface via three independent methods, invoking a tentative
cyclotron resonance scattering feature at keV, QPO production at the inner
edge of the accretion disk, and spin-up via interaction of the neutron star
magnetic field with accreting material. Each of these result in a significantly
different value. We discuss the strengths and weaknesses of each method and
infer that MAXI J0655-013 is likely to have a high surface magnetic field
strength, G.Comment: 19 pages, 10 figure, 4 tables; submitted to ApJ on May 24, 202
MAXI and NuSTAR observations of the faint X-ray transient MAXI J1848-015 in the GLIMPSE-C01 Cluster
We present the results of MAXI monitoring and two NuSTAR observations of the
recently discovered faint X-ray transient MAXI J1848-015. Analysis of the MAXI
light-curve shows that the source underwent a rapid flux increase beginning on
2020 December 20, followed by a rapid decrease in flux after only days.
NuSTAR observations reveal that the source transitioned from a bright soft
state with unabsorbed, bolometric (- keV) flux , to a low hard state with flux . Given a distance of
kpc, inferred via association of the source with the GLIMPSE-C01 cluster,
these fluxes correspond to an Eddington fraction of order for an
accreting neutron star of mass , or even lower for a more massive
accretor. However, the source spectra exhibit strong relativistic reflection
features, indicating the presence of an accretion disk which extends close to
the accretor, for which we measure a high spin, . In addition
to a change in flux and spectral shape, we find evidence for other changes
between the soft and hard states, including moderate disk truncation with the
inner disk radius increasing from to
, narrow Fe emission whose centroid
decreases from keV to keV, and an increase in
low-frequency (- Hz) variability. Due to the high spin we
conclude that the source is likely to be a black hole rather than a neutron
star, and we discuss physical interpretations of the low apparent luminosity as
well as the narrow Fe emission.Comment: 19 pages, 9 figures, 3 tables. Accepted for publication in Ap
Cerebral air embolism as a complication of peptic ulcer in the gastric tube: case report
<p>Abstract</p> <p>Background</p> <p>The reported incidence of ulcer formation in the gastric tube in esophageal replacement is rare.</p> <p>Case Presentation</p> <p>This is the first report of a case of cerebral air embolism as a result of spontaneous perforation of an ulcer in the constructed gastric tube into the pulmonary vein during post-operative follow-up in a patient with esophageal cancer.</p> <p>Conclusions</p> <p>Cerebral air embolism is a rare complication of penetrating gastric ulcer, but should be considered in patients with a history of esophagectomy with gastric conduit that present with acute neurologic findings.</p
Programmed Chemotherapy for Patients with Metastatic Unresectable Gastric Cancer
BACKGROUND: Recent advances in the treatment of metastatic unresectable gastric cancers (MGC) include the development of new antitumor drugs and new regimens for their use. However, the selection of individually designed regimens by gastric cancer (GC) subtype remains problematic. Here, we investigated the clinical usefulness of programmed chemotherapy. METHODOLOGY/PRINCIPAL FINDINGS: MGC patients were classified into three groups by clinical condition. We implemented a chemotherapy program consisting of S-1 combination regimens. Median survival time (MST) of level 1 patients was 416 days (95% CI: 313-506 days), with an overall response rate of 47%. MSTs of level 2 and 3 patients were 208 (95% CI: 153-287 days) and 95 days (95% CI: 28-136 days), respectively. Grade 3-4 toxicities were neutropenia in 12% and anorexia in 6%. All treatment- related toxicities were resolved, and no treatment-related deaths occurred. CONCLUSIONS/SIGNIFICANCE: This program provided reasonable selection of case-matching regimens and may improve the survival of patients with MGC. Further, it may represent the first clinical tool to provide efficient chemotherapy course selection for MGC. Ongoing analysis of newly developed drugs and regimens will allow the efficacy of this chemotherapy program to be improved
Biological and Structural Characterization of a Host-Adapting Amino Acid in Influenza Virus
Two amino acids (lysine at position 627 or asparagine at position 701) in the polymerase subunit PB2 protein are considered critical for the adaptation of avian influenza A viruses to mammals. However, the recently emerged pandemic H1N1 viruses lack these amino acids. Here, we report that a basic amino acid at position 591 of PB2 can compensate for the lack of lysine at position 627 and confers efficient viral replication to pandemic H1N1 viruses in mammals. Moreover, a basic amino acid at position 591 of PB2 substantially increased the lethality of an avian H5N1 virus in mice. We also present the X-ray crystallographic structure of the C-terminus of a pandemic H1N1 virus PB2 protein. Arginine at position 591 fills the cleft found in H5N1 PB2 proteins in this area, resulting in differences in surface shape and charge for H1N1 PB2 proteins. These differences may affect the protein's interaction with viral and/or cellular factors, and hence its ability to support virus replication in mammals
Transcript Annotation in FANTOM3: Mouse Gene Catalog Based on Physical cDNAs
The international FANTOM consortium aims to produce a comprehensive picture of the mammalian transcriptome, based upon an extensive cDNA collection and functional annotation of full-length enriched cDNAs. The previous dataset, FANTOM2, comprised 60,770 full-length enriched cDNAs. Functional annotation revealed that this cDNA dataset contained only about half of the estimated number of mouse protein-coding genes, indicating that a number of cDNAs still remained to be collected and identified. To pursue the complete gene catalog that covers all predicted mouse genes, cloning and sequencing of full-length enriched cDNAs has been continued since FANTOM2. In FANTOM3, 42,031 newly isolated cDNAs were subjected to functional annotation, and the annotation of 4,347 FANTOM2 cDNAs was updated. To accomplish accurate functional annotation, we improved our automated annotation pipeline by introducing new coding sequence prediction programs and developed a Web-based annotation interface for simplifying the annotation procedures to reduce manual annotation errors. Automated coding sequence and function prediction was followed with manual curation and review by expert curators. A total of 102,801 full-length enriched mouse cDNAs were annotated. Out of 102,801 transcripts, 56,722 were functionally annotated as protein coding (including partial or truncated transcripts), providing to our knowledge the greatest current coverage of the mouse proteome by full-length cDNAs. The total number of distinct non-protein-coding transcripts increased to 34,030. The FANTOM3 annotation system, consisting of automated computational prediction, manual curation, and final expert curation, facilitated the comprehensive characterization of the mouse transcriptome, and could be applied to the transcriptomes of other species
Automated Workflow for Preparation of cDNA for Cap Analysis of Gene Expression on a Single Molecule Sequencer
Background: Cap analysis of gene expression (CAGE) is a 59 sequence tag technology to globally determine transcriptional starting sites in the genome and their expression levels and has most recently been adapted to the HeliScope single molecule sequencer. Despite significant simplifications in the CAGE protocol, it has until now been a labour intensive protocol. Methodology: In this study we set out to adapt the protocol to a robotic workflow, which would increase throughput and reduce handling. The automated CAGE cDNA preparation system we present here can prepare 96 ‘HeliScope ready ’ CAGE cDNA libraries in 8 days, as opposed to 6 weeks by a manual operator.We compare the results obtained using the same RNA in manual libraries and across multiple automation batches to assess reproducibility. Conclusions: We show that the sequencing was highly reproducible and comparable to manual libraries with an 8 fold increase in productivity. The automated CAGE cDNA preparation system can prepare 96 CAGE sequencing samples simultaneously. Finally we discuss how the system could be used for CAGE on Illumina/SOLiD platforms, RNA-seq and fulllengt
Vitamin A Enhances Antitumor Effect of a Green Tea Polyphenol on Melanoma by Upregulating the Polyphenol Sensing Molecule 67-kDa Laminin Receptor
BACKGROUND: Green tea consumption has been shown to have cancer preventive qualities. Among the constituents of green tea, (-)-Epigallocatechin-3-O-gallate (EGCG) is the most effective at inhibiting carcinogenesis. However, the concentrations of EGCG that are required to elicit the anticancer effects in a variety of cancer cell types are much higher than the peak plasma concentration that occurs after drinking an equivalent of 2-3 cups of green tea. To obtain the anticancer effects of EGCG when consumed at a reasonable concentration in daily life, we investigated the combination effect of EGCG and food ingredient that may enhance the anticancer activity of EGCG on subcutaneous tumor growth in C57BL/6N mice challenged with B16 melanoma cells. METHODOLOGY/PRINCIPAL FINDINGS: All-trans-retinoic acid (ATRA) enhanced the expression of the 67-kDa laminin receptor (67LR) and increased EGCG-induced cell growth inhibition in B16 melanoma cells. The cell growth inhibition seen with the combined EGCG and ATRA treatment was abolished by treatment with an anti-67LR antibody. In addition, the combined EGCG and ATRA treatment significantly suppressed the melanoma tumor growth in mice. Expression of 67LR in the tumor increased upon oral administration of ATRA or a combined treatment of EGCG and ATRA treatment. Furthermore, RNAi-mediated silencing of the retinoic acid receptor (RAR) alpha attenuated the ATRA-induced enhancement of 67LR expression in the melanoma cells. An RAR agonist enhanced the expression levels of 67LR and increased EGCG-induced cell growth inhibition. CONCLUSIONS/SIGNIFICANCE: Our findings provide a molecular basis for the combination effect seen with dietary components, and indicate that ATRA may be a beneficial food component for cancer prevention when combined with EGCG
Evolution of multiple phosphodiesterase isoforms in stickleback involved in cAMP signal transduction pathway
Relative sea-level rise around East Antarctica during Oligocene glaciation
During the middle and late Eocene (∼48-34 Myr ago), the Earth's climate cooled and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarcticainduced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level rosedespite an overall reduction in the mass of the ocean caused by the transfer of water to the ice sheet. Here we identify the crustal response to ice-sheet growth by forcing a glacial-hydro isostatic adjustment model with an Antarctic ice-sheet model. We find that the shelf areas around East Antarctica first shoaled as upper mantle material upwelled and a peripheral forebulge developed. The inner shelf subsequently subsided as lithosphere flexure extended outwards from the ice-sheet margins. Consequently the coasts experienced a progressive relative sea-level rise. Our analysis of sediment cores from the vicinity of the Antarctic ice sheet are in agreement with the spatial patterns of relative sea-level change indicated by our simulations. Our results are consistent with the suggestion that near-field processes such as local sea-level change influence the equilibrium state obtained by an icesheet grounding line
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