Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency characterized by phagocytes devoid of a functioning nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The ...failure of CGD phagocytes to produce reactive oxygen species (ROS) results in a marked increase in the susceptibility of affected patients to life-threatening bacterial and fungal infections. This study investigated whether loading of CGD phagocytes with glucose oxidase (GO)–containing liposomes (GOLs) could restore cellular production of bactericidal ROS (eg, H2O2 and HOCl) in vitro. Results indicate that GO encapsulated in liposomes enabled NADPH oxidase-deficient phagocytes to use H2O2 for the production of highly bactericidal HOCl. The intracellular colocalization of bacteria and liposomes (or liposome-derived ferritin) was demonstrated by confocal laser microscopy and electron microscopy. After uptake of GOLs (approximately 0.2 U/mL at 1 mM total lipid concentration, size approximately 180 nm), CGD granulocytes produced HOCl levels comparable to those of normal phagocytes. Remarkably, after treatment with GOLs, CGD phagocytes killed Staphylococcus aureus as efficiently as normal granulocytes. Moreover, treated cells retained sufficient motility toward chemotactic stimuli as measured by chemotaxis assay. Side effects were evaluated by measuring the H2O2 concentrations and the production of methemoglobin in whole blood. These studies revealed that H2O2 produced by GOLs was degraded immediately by the antioxidative capacity of whole blood. Elevated methemoglobin levels were observed only after application of extremely high amounts of GOLs (2 U/mL). In summary, the application of negatively charged GOLs might provide a novel effective approach in the treatment of patients with CGD at high risk for life-threatening infections.
We present a search for flavor changing neutral currents in decays of top quarks. The analysis is based on a search for tt¯→ℓ′νℓℓ¯+jets (ℓ,ℓ′=e,μ) final states using 4.1 fb−1 of integrated luminosity ...of pp¯ collisions at s=1.96 TeV. We extract limits on the branching ratio B(t→Zq) (q=u,c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B<3.2% at 95% C.L.
b-Jet identification in the D0 experiment Adams, M.; Alton, A.; Askew, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2010, Letnik:
620, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron
p
p
¯
collider. This article ...describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.
The standard model of particle physics contains parameters-such as particle masses-whose origins are still unknown and which cannot be predicted, but whose values are constrained through their ...interactions. In particular, the masses of the top quark (Mt) and W boson (MW) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of Mt can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10-24 s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of ± 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for Mt becomes 178.0 ± 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.
We present a search for the production of a heavy gauge boson, W′, that decays to third-generation quarks, by D0 Collaboration in pp¯ collisions at s=1.96 TeV. We set 95% confidence level upper ...limits on the production cross section times branching fraction. For the first time, we set limits for arbitrary combinations of left- and right-handed couplings of the W′ boson to fermions. For couplings with the same strength as for the standard model W boson, we set the following limits, assuming that there are right-handed neutrinos νR for all three generations with M(W′)>m(νR): M(W′)>863 GeV for purely left-handed couplings, M(W′)>885 GeV for purely right-handed couplings, and M(W′)>916 GeV if both left- and right-handed couplings are present. The limit for right-handed couplings improves for M(W′)<m(νR) to M(W′)>890 GeV.
PDF
