937 research outputs found
The University of Pittsburgh: a three and three-quarter-year experience with cadaveric renal transplantation under the point system.
Eight hundred and sixty kidney transplants were performed at the University of Pittsburgh over a 3.75-year period between January 1, 1986 and October 19, 1989. Recipient selection was by means of a computerized point system designed to allocate organs equitably. Ninety-three percent 1-year patient survival and 74% 1-year graft survival were obtained in the overall group; 80% 1-year graft survival was obtained in patients receiving immunosuppression with CsA, azathioprine, and prednisone. These data serve as a measure of what can be achieved with an equitably based allocation system and can serve as a basis of comparison with other allocation protocols or new immunosuppressive regimens
IgG lymphocytotoxic antibodies in clinical liver transplantation: Studies toward further defining their significance
An Electron-Tracking Compton Telescope for a Survey of the Deep Universe by MeV gamma-rays
Photon imaging for MeV gammas has serious difficulties due to huge
backgrounds and unclearness in images, which are originated from incompleteness
in determining the physical parameters of Compton scattering in detection,
e.g., lack of the directional information of the recoil electrons. The recent
major mission/instrument in the MeV band, Compton Gamma Ray
Observatory/COMPTEL, which was Compton Camera (CC), detected mere
persistent sources. It is in stark contrast with 2000 sources in the GeV
band. Here we report the performance of an Electron-Tracking Compton Camera
(ETCC), and prove that it has a good potential to break through this stagnation
in MeV gamma-ray astronomy. The ETCC provides all the parameters of
Compton-scattering by measuring 3-D recoil electron tracks; then the Scatter
Plane Deviation (SPD) lost in CCs is recovered. The energy loss rate (dE/dx),
which CCs cannot measure, is also obtained, and is found to be indeed helpful
to reduce the background under conditions similar to space. Accordingly the
significance in gamma detection is improved severalfold. On the other hand, SPD
is essential to determine the point-spread function (PSF) quantitatively. The
SPD resolution is improved close to the theoretical limit for multiple
scattering of recoil electrons. With such a well-determined PSF, we demonstrate
for the first time that it is possible to provide reliable sensitivity in
Compton imaging without utilizing an optimization algorithm. As such, this
study highlights the fundamental weak-points of CCs. In contrast we demonstrate
the possibility of ETCC reaching the sensitivity below erg
cm s at 1 MeV.Comment: 19 pages, 12 figures, Accepted to the Astrophysical Journa
New readout and data-acquisition system in an electron-tracking Compton camera for MeV gamma-ray astronomy (SMILE-II)
For MeV gamma-ray astronomy, we have developed an electron-tracking Compton
camera (ETCC) as a MeV gamma-ray telescope capable of rejecting the radiation
background and attaining the high sensitivity of near 1 mCrab in space. Our
ETCC comprises a gaseous time-projection chamber (TPC) with a micro pattern gas
detector for tracking recoil electrons and a position-sensitive scintillation
camera for detecting scattered gamma rays. After the success of a first balloon
experiment in 2006 with a small ETCC (using a 101015 cm
TPC) for measuring diffuse cosmic and atmospheric sub-MeV gamma rays (Sub-MeV
gamma-ray Imaging Loaded-on-balloon Experiment I; SMILE-I), a (30 cm)
medium-sized ETCC was developed to measure MeV gamma-ray spectra from celestial
sources, such as the Crab Nebula, with single-day balloon flights (SMILE-II).
To achieve this goal, a 100-times-larger detection area compared with that of
SMILE-I is required without changing the weight or power consumption of the
detector system. In addition, the event rate is also expected to dramatically
increase during observation. Here, we describe both the concept and the
performance of the new data-acquisition system with this (30 cm) ETCC to
manage 100 times more data while satisfying the severe restrictions regarding
the weight and power consumption imposed by a balloon-borne observation. In
particular, to improve the detection efficiency of the fine tracks in the TPC
from 10\% to 100\%, we introduce a new data-handling algorithm in
the TPC. Therefore, for efficient management of such large amounts of data, we
developed a data-acquisition system with parallel data flow.Comment: 11 pages, 24 figure
Humoral rejection associated with antidonor lymphocytotoxic antibodies following liver transplantation.
Riemann-Hilbert problems from Donaldson-Thomas theory
We study a class of Riemann-Hilbert problems arising naturally in Donaldson-Thomas theory. In certain special cases we show that these problems have unique solutions which can be written explicitly as products of gamma functions. We briefly explain connections with Gromov-Witten theory and exact WKB analysis
Uterine selection of human embryos at implantation
Human embryos frequently harbor large-scale complex chromosomal errors that impede normal development. Affected embryos may fail to implant although many first breach the endometrial epithelium and embed in the decidualizing stroma before being rejected via mechanisms that are poorly understood. Here we show that developmentally impaired human embryos elicit an endoplasmic stress response in human decidual cells. A stress response was also evident upon in vivo exposure of mouse uteri to culture medium conditioned by low-quality human embryos. By contrast, signals emanating from developmentally competent embryos activated a focused gene network enriched in metabolic enzymes and implantation factors. We further show that trypsin, a serine protease released by pre-implantation embryos, elicits Ca2+ signaling in endometrial epithelial cells. Competent human embryos triggered short-lived oscillatory Ca2+ fluxes whereas low-quality embryos caused a heightened and prolonged Ca2+ response. Thus, distinct positive and negative mechanisms contribute to active selection of human embryos at implantation
Development of a real-time quantitative PCR assay for detection of a stable genomic region of BK virus
<p>Abstract</p> <p>Background</p> <p>BK virus infections can have clinically significant consequences in immunocompromised individuals. Detection and monitoring of active BK virus infections in certain situations is recommended and therefore PCR assays for detection of BK virus have been developed. The performance of current BK PCR detection assays is limited by the existence of viral polymorphisms, unknown at the time of assay development, resulting in inconsistent detection of BK virus. The objective of this study was to identify a stable region of the BK viral genome for detection by PCR that would be minimally affected by polymorphisms as more sequence data for BK virus becomes available.</p> <p>Results</p> <p>Employing a combination of techniques, including amino acid and DNA sequence alignment and interspecies analysis, a conserved, stable PCR target region of the BK viral genomic region was identified within the VP2 gene. A real-time quantitative PCR assay was then developed that is specific for BK virus, has an analytical sensitivity of 15 copies/reaction (450 copies/ml) and is highly reproducible (CV ≤ 5.0%).</p> <p>Conclusion</p> <p>Identifying stable PCR target regions when limited DNA sequence data is available may be possible by combining multiple analysis techniques to elucidate potential functional constraints on genomic regions. Applying this approach to the development of a real-time quantitative PCR assay for BK virus resulted in an accurate method with potential clinical applications and advantages over existing BK assays.</p
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