Four-locus high-resolution HLA typing in a sample of Mexican Americans

Mexicans are the most common minority population of the United States. From a sample of 553 bone marrow donor registrants of self-described Mexican ancestry, human leukocyte antigen (HLA) loci A, C, B and DRB1 were typed by high resolution sequence based typing (SBT) methods. A total of 47, 34, 76 and 46 distinct alleles at A, C, B and DRB1 respectively were identified, including 3 new alleles. The four-locus haplotype frequency distribution was extremely skewed with only 53.9% of 1106 chromosomes present with more than one estimated copy. Haplotypes of Native American origin were identified. These data form an initial basis for determining the requirements for an adequate donor pool for stem cell transplantation in this population.

Measurement of bottom versus charm as a function of transverse momentum with electron-hadron correlations in p + p collisions at square root of s = 200 GeV

The momentum distribution of electrons from semileptonic decays of charm and bottom quarks for midrapidity |y|<0.35 in p+p collisions at square root of s=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range 2<pT<7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D-->e(+/-)K(-/+)X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in pT. A fixed-order-plus-next-to-leading-log perturbative quantum chromodynamics calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is sigma(bb)=3.2(-1.1)(+1.2)(stat)(-1.3)(+1.4)(syst)mub.

Gluon-spin contribution to the proton spin from the double-helicity asymmetry in inclusive pi0 production in polarized p+p collisions at [sqrt]s=200 GeV

The double helicity asymmetry in neutral pion production for pT=1 to 12 GeV/c was measured with the PHENIX experiment to access the gluon-spin contribution, DeltaG, to the proton spin. Measured asymmetries are consistent with zero, and at a theory scale of micro2=4 GeV2 a next to leading order QCD analysis gives DeltaG[0.02,0.3]=0.2, with a constraint of -0.7<DeltaG[0.02,0.3]<0.5 at Deltachi2=9 (approximately 3sigma) for the sampled gluon momentum fraction (x) range, 0.02 to 0.3. The results are obtained using predictions for the measured asymmetries generated from four representative fits to polarized deep inelastic scattering data. We also consider the dependence of the DeltaG constraint on the choice of the theoretical scale, a dominant uncertainty in these predictions.

The lupus-susceptibility gene kallikrein downmodulates antibody-mediated glomerulonephritis

Sle3 is a NZM2410/NZW-derived lupus-susceptibility interval on murine chromosome 7, which is associated with spontaneous lupus nephritis (SLN), and also anti-GBM-induced glomerulonephritis (GN). The tissue kallikrein gene cluster is located within the Sle3 interval and constitutes potential candidate genes for this locus. We have recently reported that renal kallikrein expression was upregulated by anti-GBM antibody challenge in a strain-specific manner and that it was significantly underexpressed in the anti-GBM-sensitive strains, including B6.Sle3. Further sequencing and functional studies reported earlier provided evidence that kallikreins could constitute disease genes in lupus. In this report, we have used an adenoviral vector to deliver the klk1 gene to B6.Sle3 congenics to directly test if kallikreins might have a protective effect against anti-GBM-induced nephritis. Our data show that klk1 gene delivery ameliorated anti-GBM-induced nephritis in B6.Sle3 congenics. Taken together with earlier studies, these findings indicate that kallikreins play an important protective role in autoantibody-initiated GN and could constitute potential candidate genes for anti-GBM-induced GN and SLN.

Effect of a high-kappa environment on charge carrier mobility in graphene

It is widely assumed that the dominant source of scattering in graphene is charged impurities in a substrate. We have tested this conjecture by studying graphene placed on various substrates and in high-kappa media. Unexpectedly, we have found no significant changes in carrier mobility either for different substrates or by using glycerol, ethanol, and water as a top dielectric layer. This suggests that Coulomb impurities are not the scattering mechanism that limits the mean free path attainable for graphene on a substrate.

Curing of four different plasmids in Yersinia pestis using plasmid incompatibility

AIMS

Plasmids are critical for the pathogenicity of Yersinia pestis. In order to carry out a systematic investigation of their role in pathogenesis, we cured plasmids from Y. pestis.

METHODS AND RESULTS

Each plasmid's replicon of Y. pestis was cloned into plasmid pEX18Gm containing a counter-selectable sacB gene, and was then introduced into Y. pestis strain 201 by electroporation. Strains containing recombinant plasmids were cultivated under antibiotic selection. The resultant plasmid-curing colonies, identified by specific polymerase chain reactions, were then cured off pEX18Gm under sucrose pressure. This method was used to successfully cure all four plasmids of Y. pestis, singly or in different combinations.

CONCLUSIONS

Naturally evolving plasmids in Y. pestis are difficult to remove by conventional curing methods. We employed a method based on plasmid incompatibility to cure the plasmids from Y. pestis, which confirmed the efficacy of this method for curing plasmids with different types of replicons from one bacterium.

SIGNIFICANCE AND IMPACT OF THE STUDY

There have been no reports on the curing of multiple plasmids by using replication mechanisms from one bacterium with this technique. In the present study, we were able to successfully apply this methodology to cure four plasmids from Y. pestis, confirming its feasibility.

The formation of nanocrystallite bone-like apatite on chemically treated Ti-24Nd-4Zr-7.9Sn alloy

Ti-24Nd-4Zr-7.9Sn alloy with low elastic modulus and high strength is a great candidate for artificial biomaterials used in orthopedic and dental implants. In order to improve biocompatibility, a biomimetic process was employed to deposit a bone-like apatite nanocrystal coating on alloy. Analysis of the coatings showed that a net-like Na2TiO3 layer with about 100 nm in size was formed on Ti-24Nd-4Zr-7.9Sn treated by NaOH. Consequently, a carbonated apatite nanocrystal coating, namely bone-like apatite, was biomimetically deposited on Na2TiO3 layer, which has similar mineral composition to that of natural bone. The growth mechanism of bone-like layer is also discussed.

Reversible movement of homogenously nucleated dislocations in a beta-titanium alloy

We demonstrate reversible movement of 1/2[11[over ]0](110) dislocation loops generated from nanodisturbances in a beta-titanium alloy. High resolution transmission electron microscope observations during an in situ tensile test found three reversible deformation mechanisms, nanodisturbances, dislocation loops and martensitic transformation, that are triggered in turn with increasing applied stress. All three mechanisms contribute to the nonlinear elasticity of the alloy. The experiments also revealed the evolution of the dislocation loops to disclination dipoles that cause severe local lattice rotations.