4,137 research outputs found
Thymus transplantation for complete DiGeorge syndrome: European experience
Background: Thymus transplantation is a promising strategy for the treatment of athymic complete DiGeorge syndrome (cDGS). Methods: Twelve patients with cDGS were transplanted with allogeneic cultured thymus. Objective: To confirm and extend the results previously obtained in a single centre. Results: Two patients died of pre-existing viral infections without developing thymopoeisis and one late death occurred from autoimmune thrombocytopaenia. One infant suffered septic shock shortly after transplant resulting in graft loss and the need for a second transplant. Evidence of thymopoeisis developed from 5-6 months after transplantation in ten patients. The median (range) of circulating naïve CD4 counts (x10663 /L) were 44(11-440) and 200(5-310) at twelve and twenty-four months post-transplant and T-cell receptor excision circles were 2238 (320-8807) and 4184 (1582 -24596) per106 65 T-cells. Counts did not usually reach normal levels for age but patients were able to clear pre-existing and later acquired infections. At a median of 49 months (22-80), eight have ceased prophylactic antimicrobials and five immunoglobulin replacement. Histological confirmation of thymopoeisis was seen in seven of eleven patients undergoing biopsy of transplanted tissue including five showing full maturation through to the terminal stage of Hassall body formation. Autoimmune regulator (AIRE) expression was also demonstrated. Autoimmune complications were seen in 7/12 patients. In two, early transient autoimmune haemolysis settled after treatment and did not recur. The other five suffered ongoing autoimmune problems including: thyroiditis (3); haemolysis (1), thrombocytopaenia (4) and neutropenia (1). Conclusions: This study confirms the previous reports that thymus transplantation can reconstitute T cells in cDGS but with frequent autoimmune complications in survivors
A search for X-rays from UV Ceti flare stars
A search of MIT/OSO-7 data was made for evidence of X-ray emission from flares of UV Ceti flare stars. Observations from McDonald Observatory were used to identify the times of optical flares. The only instance of coincident coverage occurred on 1974 January 21 UT at 03:43:26 GMT for delta m(u)=0.86 flare of YZ CMi. No radio coverage of this particular event was obtained. Upper limits (3 sigma) of 0.8, 1.0, and 0.7 photons/sq cm-sec on the observed X-ray flux were set for the energy ranges greater than or approximately equal to 15, greater than or approximately equal to 3, and 1-10 keV, respectively
Resonance production in heavy ion collisions
Recent results of resonance production from RHIC at
200 GeV and SPS at 17 GeV are presented and discussed in
terms of the evolution and freeze-out conditions of a hot and dense fireball
medium. Yields and spectra are compared with thermal model predictions at
chemical freeze-out. Deviations in the low transverse momentum region of the
resonance spectrum of the hadronic decay channel, suggest a strongly
interaction hadronic phase between chemical and kinetic freeze-out. Microscopic
models including resonance rescattering and regeneration are able to describe
the trend of the data. The magnitude of the regeneration cross sections for
different inverse decay channels are discussed. Model calculations which
include elastic hadronic interactions between chemical freeze-out and thermal
freeze-out based on the K(892)/K and (1520)/ ratios suggest a
time between two freeze-outs surfaces of 4 fm/c. The difference
in momentum distributions and yields for the (1020) resonance
reconstructed from the leptonic and hadronic decay channels at SPS energy are
discussed taking into account the impact of a hadronic phase and possible
medium modifications.Comment: 8 pages, 4 figures, conference proceedings (SQM2004
What do we learn from Resonance Production in Heavy Ion Collisions?
Resonances with their short life time and strong coupling to the dense and
hot medium are suggested as a signature of the early stage of the fireball
created in a heavy ion collision \cite{rap00,lut01,lut02}. The comparison of
resonances with different lifetimes and quark contents may give information
about time evolution and density and temperature of during the expanding of
fireball medium. Resonances in elementary reactions have been measured since
1960. Resonance production in elementary collisions compared with heavy ion
collisions where we expect to create a hot and dense medium may show the direct
of influence of the medium on the resonances. This paper shows a selection of
the recent resonance measurements from SPS and RHIC heavy ion colliders.Comment: 10 pages, 8 figures, HotQuarks 2004 conference proceeding
Quantification of total T-cell receptor diversity by flow cytometry and spectratyping
BACKGROUND: T-cell receptor diversity correlates with immune competency and is of particular interest in patients undergoing immune reconstitution. Spectratyping generates data about T-cell receptor CDR3 length distribution for each BV gene but is technically complex. Flow cytometry can also be used to generate data about T-cell receptor BV gene usage, but its utility has not been compared to or tested in combination with spectratyping. RESULTS: Using flow cytometry and spectratype data, we have defined a divergence metric that quantifies the deviation from normal of T-cell receptor repertoire. We have shown that the sample size is a sensitive parameter in the predicted flow divergence values, but not in the spectratype divergence values. We have derived two ways to correct for the measurement bias using mathematical and statistical approaches and have predicted a lower bound in the number of lymphocytes needed when using the divergence as a substitute for diversity. CONCLUSIONS: Using both flow cytometry and spectratyping of T-cells, we have defined the divergence measure as an indirect measure of T-cell receptor diversity. We have shown the dependence of the divergence measure on the sample size before it can be used to make predictions regarding the diversity of the T-cell receptor repertoire
On the Mechanisms of Haemodialysis-induced Neutropenia: A Study with Five New and Re-used Membranes
A prospective study was undertaken in 12 haemodialysed patients successively treated on five new as well as re-used dialyser membranes, that is cuprophane, cellulose acetate, polysulphone, polycarbonate, and polyacrylonitrile. A significant reduction of neutrophils occurred with every membrane during their first use, which improved only with cuprophane upon re-use. Thrombocytopenia was noted only when neutropenia reached very low values. Monocyte reduction occurred on cuprophane, cellulose acetate and polycarbonate, but did not improve during second use. C3d accumulation paralleled the time course of neutropenia only with cuprophane and cellulose acetate. Plasma collected at the extreme of neutropenia induced aggregation of control and predialysis cells, but did not aggregate autologous dialysed neutrophils collected at 5 min. Our data indicate that the mechanism linking complement activation to neutropenia is probably triggered by more than one facto
Statistical hadronization phenomenology in fluctuations at ultra-relativistic energies
We discuss the information that can be obtained from an analysis of
fluctuations in heavy ion collisions within the context of the statistical
model of particle production. We then examine the recently published
experimental data on ratio fluctuations, and use it to obtain constraints on
the statistical properties (physically relevant ensemble, degree of chemical
equilibration, scaling across energies and system sizes) and freeze-out
dynamics (amount of reinteraction between chemical and thermal freeze-out) of
the system.Comment: Proceedings, SQM2009. Fig. 4, the main results figure, was wrong due
to editing mistake, now correcte
ÎNp63-mediated regulation of hyaluronic acid metabolism and signaling supports HNSCC tumorigenesis
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and several molecular pathways that underlie the molecular tumorigenesis of HNSCC have been identified. Among them, amplification or overexpression of ÎNp63 isoforms is observed in the majority of HNSCCs. Here, we unveiled a ÎNp63-dependent transcriptional program able to regulate the metabolism and the signaling of hyaluronic acid (HA), the major component of the extracellular matrix (ECM). We found that âNp63 is capable of sustaining the production of HA levels in cell culture and in vivo by regulating the expression of the HA synthase HAS3 and two hyaluronidase genes, HYAL-1 and HYAL-3. In addition, âNp63 directly regulates the expression of CD44, the major HA cell membrane receptor. By controlling this transcriptional program, âNp63 sustains the epithelial growth factor receptor (EGF-R) activation and the expression of ABCC1 multidrug transporter gene, thus contributing to tumor cell proliferation and chemoresistance. Importantly, p63 expression is positively correlated with CD44, HAS3, and ABCC1 expression in squamous cell carcinoma datasets and p63-HA pathway is a negative prognostic factor of HNSCC patient survival. Altogether, our data shed light on a âNp63-dependent pathway functionally important to the regulation of HNSCC progression
On the ultra-compact nature of 4U1822-000
We report the discovery of a periodic modulation in the optical lightcurve of
the candidate ultra-compact X-ray binary 4U1822-000. Using time-resolved
optical photometry taken with the William Herschel Telescope we find evidence
for a sinusoidal modulation with a semi-amplitude of 8 percent and a period of
191 min, which is most likely close to the true orbital period of the binary.
Using the van Paradijs & McClintock relation for the absolute magnitude and the
distance modulus allowing for interstellar reddening, we estimate the distance
to 4U1822-000 to be 6.3 kpc. The long orbital period and casts severe doubts on
the ultra-compact nature of 4U1822-000.Comment: 3 pages, 1 figure, accepted by MNRA
High Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High Energy Transmission Grating Spectrometer
High resolution spectra of the active binary Capella (G8 III + G1 III)
covering the energy range 0.4-8.0 keV (1.5-30 Angstroms) show a large number of
emission lines, demonstrating the performance of the HETGS. A preliminary
application of plasma diagnostics provides information on coronal temperatures
and densities. Lines arising from different elements in a range of ionization
states indicate that Capella has plasma with a broad range of temperatures,
from log T = 6.3 to 7.2, generally consistent with recent results from
observations with the Extreme Ultraviolet Explorer (EUVE) and the Advanced
Satellite for Cosmology and Astrophysics (ASCA). The electron density is
determined from He-like O VII lines, giving the value N_e=10^10 cm^-3 at
T_e=2*10^6 K; He-like lines formed at higher temperatures give only upper
limits to the electron density. The density and emission measure from O VII
lines together indicate that the coronal loops are significantly smaller than
the stellar radius.Comment: 9 pages, 3 figures (1 color) accepted for ApJ
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