10,399 research outputs found
High-grade B-Cell lymphoma with MYC and BCL6 rearrangements associated with Richter transformation of chronic lymphocytic leukemia
Richter transformation (RT), or Richter syndrome, is defined as the transformation of chronic lymphocytic leukemia (CLL) to an aggressive B-cell lymphoma. The vast majority, up to 99%, transform into diffuse large B-cell lymphoma (DLBCL), with a small subset (<1%) becoming classical Hodgkin lymphoma. Approximately half of RT cases progress through a pathway involving dysregulation of C-MYC. High-grade B-cell lymphoma (HGBL) is a recent diagnostic category of aggressive B-cell lymphomas set forth in the updated 2017 WHO Classification of Hematopoietic and Lymphoid Tissues. HGBL with MYC and BCL2 and/or BCL6 rearrangements, formerly “double-hit” and “triple-hit” lymphomas, comprise the majority of HGBL cases. Patients with HGBL have a worse prognosis than those with diffuse large B-cell lymphoma. We present a case of RT with rearrangements of MYC and BCL6. To our knowledge, there are no reported cases of RT with a “double-hit” lymphoma genotype
Measurements of the Diffuse Ultraviolet Background and the Terrestrial Airglow with the Space Telescope Imaging Spectrograph
Far-UV observations in and near the Hubble Deep Fields demonstrate that the
Space Telescope Imaging Spectrograph (STIS) can potentially obtain unique and
precise measurements of the diffuse far-ultraviolet background. Although STIS
is not the ideal instrument for such measurements, high-resolution images allow
Galactic and extragalactic objects to be masked to very faint magnitudes, thus
ensuring a measurement of the truly diffuse UV signal. The programs we have
analyzed were not designed for this scientific purpose, but would be sufficient
to obtain a very sensitive measurement if it were not for a weak but
larger-than-expected signal from airglow in the STIS 1450-1900 A bandpass. Our
analysis shows that STIS far-UV crystal quartz observations taken near the limb
during orbital day can detect a faint airglow signal, most likely from NI\1493,
that is comparable to the dark rate and inseparable from the far-UV background.
Discarding all but the night data from these datasets gives a diffuse
far-ultraviolet background measurement of 501 +/- 103 ph/cm2/sec/ster/A, along
a line of sight with very low Galactic neutral hydrogen column (N_HI = 1.5E20
cm-2) and extinction (E(B-V)=0.01 mag). This result is in good agreement with
earlier measurements of the far-UV background, and should not include any
significant contribution from airglow. We present our findings as a warning to
other groups who may use the STIS far-UV camera to observe faint extended
targets, and to demonstrate how this measurement may be properly obtained with
STIS.Comment: 7 pages, Latex. 4 figures. Uses corrected version of emulateapj.sty
and apjfonts.sty (included). Accepted for publication in A
A Comprehensive Survey of Hydrogen Chloride in the Galaxy
We report new observations of the fundamental transition of HCl (at
625.918GHz) toward a sample of 25 galactic star-forming regions, molecular
clouds, and evolved stars, carried out using the Caltech Submillimeter
Observatory. Fourteen sources in the sample are also observed in the
corresponding H\tscl\ transition (at 624.978GHz). We have obtained
clear detections in all but four of the targets, often in emission. Absorptions
against bright background continuum sources are also seen in nine cases,
usually involving a delicate balance between emission and absorption features.
From RADEX modeling, we derive gas densities and HCl column densities for
sources with HCl emission. HCl is found in a wide range of environments, with
gas densities ranging from to ~cm. The HCl abundance
relative to H is in the range of . Comparing with the
chlorine abundance in the solar neighborhood, this corresponds to a chlorine
depletion factor of up to 400, assuming that HCl accounts for one third
of the total chlorine in the gas phase. The [\tfcl]/[\tscl] isotopic ratio is
rather varied, from unity to 5, mostly lower than the terrestrial value
of 3.1. Such variation is highly localized, and could be generated by the
nucleosynthesis in supernovae, which predicts a \tscl\ deficiency in most
models. The lower ratios seen in W3IRS4 and W3IRS5 likely confine the
progenitors of the supernovae to stars with relatively large mass
(\ga25M_\sun) and high metallicity (Z0.02).Comment: 11 pages, 5 figures, accepted by Ap
Human cytomegalovirus US28 facilitates cell-to-cell viral dissemination
Human cytomegalovirus (HCMV) encodes a number of viral proteins with homology to cellular G protein-coupled receptors (GPCRs). These viral GPCRs, including US27, US28, UL33, and UL78, have been ascribed numerous functions during infection, including activating diverse cellular pathways, binding to immunomodulatory chemokines, and impacting virus dissemination. To investigate the role of US28 during virus infection, two variants of the clinical isolate TB40/E were generated: TB40/E-US28(YFP) expressing a C-terminal yellow fluorescent protein tag, and TB40/E-FLAG(YFP) in which a FLAG-YFP cassette replaces the US28 coding region. The TB40/E-US28(YFP) protein localized as large perinuclear fluorescent structures at late times post-infection in fibroblasts, endothelial, and epithelial cells. Interestingly, US28(YFP) is a non-glycosylated membrane protein throughout the course of infection. US28 appears to impact cell-to-cell spread of virus, as the ΔUS28 virus (TB40/E-FLAG(YFP)) generated a log-greater yield of extracellular progeny whose spread could be significantly neutralized in fibroblasts. Most strikingly, in epithelial cells, where dissemination of virus occurs exclusively by the cell-to-cell route, TB40/E-FLAG(YFP) (ΔUS28) displayed a significant growth defect. The data demonstrates that HCMV US28 may contribute at a late stage of the viral life cycle to cell-to-cell dissemination of virus
Comparison of Robot-Assisted Nephrectomy with Laparoscopic and Hand-Assisted Laparoscopic Nephrectomy
Early experience with robotic assistance for radical and simple nephrectomy offers no significant advantage over traditional laparoscopic or hand-assisted approaches
Direct CP Violation, Branching Ratios and Form Factors , in Decays
The and transitions involved in hadronic B decays are
investigated in a phenomenological way through the framework of QCD
factorization. By comparing our results with experimental branching ratios from
the BELLE, BABAR and CLEO Collaborations for all the B decays including either
a pion or a kaon, we propose boundaries for the transition form factors and depending on the CKM matrix element parameters and
. From this analysis, the form factors required to reproduce the
experimental data for branching ratios are and
. We calculate the direct CP violating asymmetry
parameter, , for and decays, in the case where mixing effects are taken into
account. Based on these results, we find that the direct CP asymmetry for
, ,
, and , reaches its maximum when the invariant mass is
in the vicinity of the meson mass. The inclusion of
mixing provides an opportunity to erase, without ambiguity, the phase
uncertainty mod in the determination of the CKM angles in case
of and in case of .Comment: 74 pages, 15 figures, 8 tables. A few misprints corrected, two
references adde
A Mathematical Framework for Agent Based Models of Complex Biological Networks
Agent-based modeling and simulation is a useful method to study biological
phenomena in a wide range of fields, from molecular biology to ecology. Since
there is currently no agreed-upon standard way to specify such models it is not
always easy to use published models. Also, since model descriptions are not
usually given in mathematical terms, it is difficult to bring mathematical
analysis tools to bear, so that models are typically studied through
simulation. In order to address this issue, Grimm et al. proposed a protocol
for model specification, the so-called ODD protocol, which provides a standard
way to describe models. This paper proposes an addition to the ODD protocol
which allows the description of an agent-based model as a dynamical system,
which provides access to computational and theoretical tools for its analysis.
The mathematical framework is that of algebraic models, that is, time-discrete
dynamical systems with algebraic structure. It is shown by way of several
examples how this mathematical specification can help with model analysis.Comment: To appear in Bulletin of Mathematical Biolog
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