| 1. |
- Li, J J, et al.
(author)
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Electrophoretic and mass spectrometric strategies for profiling bacterial lipopolysaccharides
- 2005
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In: MOLECULAR BIOSYSTEMS. - : Royal Society of Chemistry (RSC). - 1742-206X .- 1742-2051. ; 1:1, s. 46-52
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Journal article (peer-reviewed)abstract
- Capillary electrophoresis (CE) is a high-resolution separation technique that has been widely used for trace analysis in biological samples. On-line capillary electrophoresis-electro spray mass spectrometry (CE-MS) was developed for the analysis of lipopolysaccharide (LPS) glycoforms from the gram-negative bacteria, Haemophilus influenzae. In this paper, we report on the application of CE-MS to characterize structural differences in O-deacylated LPS samples from H. influenzae strains Rd 11.7 and 375.1. The resolution capability of on-line CE-MS was first demonstrated by analysis of a complex LPS mixture from H. influenzae strain Rd 11.7. This strain contains a mixture of isomeric glycoforms differing in the number and positions of hexose moieties. Sialic acid containing glycoforms were also determined. Structural features of LPS from a lic1 mutant of H. influenzae strain 375 (375.1) were studied using on-line CE-MS/MS. With the separation provided by CE, two isomeric glycoforms differing in the location of phosphoethanolamine substituents were characterized by tandem mass spectrometry.
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| 2. |
- Yildirim, Håkan H., et al.
(author)
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An alternate pattern for globoside oligosaccharide expression in Haemophilus influenzae lipopolysaccharide : Structural diversity in nontypeable strain 1124
- 2005
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In: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 44:13, s. 5207-5224
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Journal article (peer-reviewed)abstract
- Common structural motifs of Haemophilus influenzae lipopolysaccharide (LPS) are globotetraose [beta-D-GalpNAc-(1 -> 3)-alpha-D-Galp-(1 -> 4)-beta-D-Galp-(1 -> 4)-beta-D-Glcp] and its truncated versions globoside [alpha-D-Galp-(1 -> 4)-beta-D-Galp-(1 -> 4)-beta-D-Glcp] and lactose [beta-D-Galp-(1 -> 4)-beta-D-Glcp] linked to the tenninal heptose (HepIII) of the triheptosyl inner-core moiety L-alpha-D-Hepp-(1 -> 2)-[PEA -> 6]-L-alpha-D-Hepp-(1 -> 3)L-alpha-D-Hepp-(1 -> 5)-[PPEA -> 4]-alpha-Kdo-(2 -> 6)-lipid A. We report here structural studies of LPS from nontypeable H. influenzae strain 1124 expressing these motifs linked to both the proximal heptose (HepI) and HepIII at the same time. This novel finding was obtained by structural studies of LPS using NMR techniques and electrospray ionization mass spectrometry (ESI-MS) on O-deacylated LPS and core oligosaccharide material (OS) as well as ESI-MSn on permethylated dephosphorylated OS. The use of defined mutants allowed us to confirm structures unambiguously and understand better the biosynthesis of each of the globotetraose units. We found that lgtC is involved in the expression of beta-D-Galp-(1 -> 4)-beta-D-Galp in both extensions, whereas lic2A directs only the expression Of beta-D-Ga1p-(1 -> 4)-beta-D-Glcp when linked to HepIII. The LPS of NTHi strain 1124 contained sialylated glycoforms that were identified by CE-ESI-MS/MS. A common sialylated structure in H. influenzae LPS is sialyllactose linked to HepIII. This structure exists in strain 1124. However, results for the lpsA mutant indicate that sialyllactose extends from HepI as well, a molecular environment for sialyllactose in H. influenzae that has not been reported previously. In addition, the LPS was found to carry phosphoryleholine, O-linked glycine, and a third PEA group which was linked to O3 of HepIII.
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| 3. |
- Yildirim, Håkan H, et al.
(author)
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Complex O-acetylation in non-typeable Haemophilus influenzae lipopolysaccharide : evidence for a novel site of O-acetylation
- 2005
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In: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 340:17, s. 2598-2611
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Journal article (peer-reviewed)abstract
- The structure of the lipopolysaccharide (LPS) of non-typeable Haemophilus influenzae strain 723 has been elucidated using NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) on O-deacylated LPS and core oligosaccharide material (OS), as well as ESI-MSn on permethylated dephosphorylated OS. It was found that the LPS contains the common structural element of H. influenzae, L-alpha-D-Hepp-(1 -> 2)-[PEtn -> 6]-L-alpha-D-Hepp-(1 -> 3)-[beta-D-Glcp-(1 -> 4)]-L-alpha-D-Hepp-(1 -> 5)-[PPEtn -> 4]-alpha-Kdo-(2 -> 6)-Lipid A, in which the beta-D-Glcp residue (GlcI) is substituted by phosphocholine at O-6 and the distal heptose residue (HepIII) by PEW at O-3, respectively. In a subpopulation of glycoforms O-2 of HepIII was substituted by beta-D-Galp-(1 -> 4)-beta-D-Glcp-(1 -> or beta-D-Glcp-(1 ->. Considerable heterogeneity of the LPS was due to the extent of substitution by O-acetyl groups (Ac) and ester-linked glycine of the core oligosaccharide. The location for glycine was found to be at Kdo. Prominent acetylation sites were found to be at GlcI, HepIII, and the proximal heptose (HepI) residue of the triheptosyl moiety. Moreover, GlcI was acetylated at O-3 and/or O-4 and HepI was acetylated at O-2 as evidenced by capillary electrophoresis ESI-MS" in combination with NMR analyses. This is the first study to show that an acetyl group can substitute HepI of the inner-core region of H. influenzae LPS.
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| 4. |
- Abazov, M, et al.
(author)
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Combination of t(t)over-bar cross section measurements and constraints on the mass of the top quark and its decays into charged Higgs bosons
- 2009
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 80, s. 071102-
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Journal article (peer-reviewed)abstract
- We combine measurements of the top quark pair production cross section in p (p) over bar collisions in the l + jets, ll, and tau l final states ( where l is an electron or muon) at a center of mass energy of root s = 1.96 TeV in 1 fb(-1) of data collected with the D0 detector. For a top quark mass of 170 GeV/c(2), we obtain sigma(t (t) over bar) = 8.18(-0.87)(+0.98) pb in agreement with the theoretical prediction. Based on predictions from higher order quantum chromodynamics, we extract a mass for the top quark from the combined t (t) over bar cross section, consistent with the world average of the top quark mass. In addition, the ratios of t (t) over bar cross sections in different final states are used to set upper limits on the branching fractions B(t -> H(+)b -> tau(+) vb) and B(t -> H(+)b -> c (s) over barb) as a function of the charged Higgs boson mass.
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| 5. |
- Abazov, M, et al.
(author)
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Direct Measurement of the Mass Difference between Top and Antitop Quarks
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:13, s. 132001-
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Journal article (peer-reviewed)abstract
- We present a measurement of the mass difference between t and (t) over bar quarks in lepton + jets final states of t (t) over bar events in 1 fb(-1) of data collected with the D0 detector from Fermilab Tevatron Collider p (p) over bar collisions at root s = 1.96 TeV. The measured mass difference of 3.8 +/- 3.7 GeV is consistent with the equality of t and (t) over bar masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.
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| 6. |
- Abazov, M, et al.
(author)
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Evidence of WW and WZ Production with lepton plus jets Final States in pp Collisions at root s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:16, s. 161801-
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Journal article (peer-reviewed)abstract
- We present first evidence for WW+WZ production in lepton+jets final states at a hadron collider. The data correspond to 1.07 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is < 5.4x10(-6), which corresponds to a significance of 4.4 standard deviations.
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| 7. |
- Abazov, M, et al.
(author)
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Measurement of B-s(0) Mixing Parameters from the Flavor-Tagged Decay B-s(0)-> J/psi phi
- 2008
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:24, s. 241801-:101, s. 241801-
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Journal article (peer-reviewed)abstract
- From an analysis of the flavor-tagged decay B-s(0)-> J/psi phi we obtain the width difference between the B-s(0) light and heavy mass eigenstates, Delta Gamma(s)=0.19 +/- 0.07(stat)(-0.01)(+0.02)(syst) ps(-1), and the CP-violating phase, phi(s)=-0.57(-0.30)(+0.24)(stat)(-0.02)(+0.08)(syst). The allowed 90% CL intervals of Delta Gamma(s) and phi(s) are 0.06
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| 8. |
- Abazov, M, et al.
(author)
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Measurement of differential Z/gamma* plus jet plus X cross sections in p(p)over-bar collisions at root S=1.96 TeV
- 2008
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 669:5, s. 278-286
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Journal article (peer-reviewed)abstract
- We present new measurements of differential cross sections for Z/gamma* (-> mu mu) + jet + X production in a 1 fb(-1) data sample collected with the DO detector in p (p) over bar collisions at root s = 1.96 TeV. Results include the first measurements differential in the Z/gamma* transverse momentum and rapidity, as well as new measurements differential in the leading jet transverse momentum and rapidity. Next-to-leading order perturbative QCD predictions are compared to the measurements, and reasonable agreement is observed, except in the region of low Z/gamma* transverse momentum. Predictions from two event generators based on matrix elements and parton showers, and one pure parton shower event generator are also compared to the measurements. These show significant overall normalization differences to the data and have varied success in describing the shape of the distributions.
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| 9. |
- Abazov, M, et al.
(author)
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Measurement of Dijet Angular Distributions at s=1.96 TeV and Searches for Quark Compositeness and Extra Spatial Dimensions
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:19, s. 191803-
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Journal article (peer-reviewed)abstract
- We present the first measurement of dijet angular distributions in pp collisions at s=1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb(-1) collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV-1 scale extra dimensions. For all models considered, we set the most stringent direct limits to date.
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| 10. |
- Abazov, M, et al.
(author)
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Measurement of gamma + b + X and gamma + c + X Production Cross Sections in pp > Collisions at s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:19, s. 192002-
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Journal article (peer-reviewed)abstract
- First measurements of the differential cross sections d(3)sigma/(dp(T)(gamma)dy(gamma)dy(jet)) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30 < p(T)(gamma)< 150 GeV, photon rapidities |y(gamma)|< 1.0, jet rapidities |y(jet)|< 0.8, and jet transverse momenta p(T)(jet)> 15 GeV. The results are based on an integrated luminosity of 1 fb(-1) in pp collisions at s=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.
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