Regulation of Transgenic Class II Major Histocompatibility Genes in Murine Langerhans Cells

I-E is a class II major histocompatibility complex molecule normally expressed by Langerhans cells, A series of transgenic mice were developed previously that carry Eαd gene constructs with promoter-region deletions that cause expression of I-E by different cell types when maintained on a B6 (I-E[–]) genetic background. To study cis-acting gene sequences that regulate expression of class II proteins by Langerhans cells, we identified trans genie I-E expression by tissue immunoperoxidase staining and by epidermal cell suspension lmmunofluorescence cytometry. Mice with a transgene containing 1.4 kilobase pairs (kb) of flanking sequence 5' to the Eα initiation site expressed barely detectable levels of I-E on a tiny percentage of Langerhans cells, indicating that sequences promoting Langerhans cell expression of Eα exist between 2.0 and 1.4 kb 5' of the Eα initiation site. Removal of an additional 170 bp of 5' flanking sequence caused near-normal levels of expression by approximately one third of epidermal Langerhans cells, which contrasts with studies that showed minimal transgene expression by splenic dendritic cells in these animals, Thus, sequences between 1.4 and 1.23 kb 5' of the Eα initiation site decrease expression of I-E by epidermal Laugerhans cells, but enable I-E expression by splenic dendritic cells, These studies identify Langerhans cell-specific regulatory sequences and genetic regions controlling major histocompatibility complex class II gene expression in Langerhans cells and splenic dendritic cells. The genetic regions identified may be particularly important because differential regulation of class II major histocompatibility complex protein synthesis by Langerhans cells and dendritic cells may be crucial to immune functions of intact animals

Yersinia pestis Interacts With SIGNR1 (CD209b) for Promoting Host Dissemination and Infection

Yersinia pestis, a Gram-negative bacterium and the etiologic agent of plague, has evolved from Yersinia pseudotuberculosis, a cause of a mild enteric disease. However, the molecular and biological mechanisms of how Y pseudotuberculosis evolved to such a remarkably virulent pathogen, Y pestis, are not clear. The ability to initiate a rapid bacterial dissemination is a characteristic hallmark of Y pestis infection. A distinguishing characteristic between the two Yersinia species is that Y pseudotuberculosis strains possess an O-antigen of lipopolysaccharide (LPS) while Y pestis has lost the O-antigen during evolution and therefore exposes its core LPS. In this study, we showed that Y pestis utilizes its core LPS to interact with SIGNR1 (CD209b), a C-type lectin receptor on antigen presenting cells (APCs), leading to bacterial dissemination to lymph nodes, spleen and liver, and the initiation of a systemic infection. We therefore propose that the loss of O-antigen represents a critical step in the evolution of Y pseudotuberculosis into Y pestis in terms of hijacking APCs, promoting bacterial dissemination and causing the plague.Peer reviewe

Genome-Wide Association Study for Femoral Neck Bone Geometry

Poor femoral neck bone geometry at the femur is an important risk factor for hip fracture. We conducted a genome-wide association study (GWAS) of femoral neck bone geometry, examining approximately 379,000 eligible single-nucleotide polymorphisms (SNPs) in 1000 Caucasians. A common genetic variant, rs7430431 in the receptor transporting protein 3 (RTP3) gene, was identified in strong association with the buckling ratio (BR, P = 1.6 × 10−7), an index of bone structural instability, and with femoral cortical thickness (CT, P = 1.9 × 10−6). The RTP3 gene is located in 3p21.31, a region that we found to be linked with CT (LOD = 2.19, P = 6.0 × 10−4) in 3998 individuals from 434 pedigrees. The replication analyses in 1488 independent Caucasians and 2118 Chinese confirmed the association of rs7430431 to BR and CT (combined P = 7.0 × 10−3 for BR and P = 1.4 × 10−2 for CT). In addition, 350 hip fracture patients and 350 healthy control individuals were genotyped to assess the association of the RTP3 gene with the risk of hip fracture. Significant association between a nearby common SNP, rs10514713 of the RTP3 gene, and hip fracture (P = 1.0 × 10−3) was found. Our observations suggest that RTP3 may be a novel candidate gene for femoral neck bone geometry. © 2010 American Society for Bone and Mineral Researc

Diverse topological states in a ternary NdAsPd compound

© The Royal Society of Chemistry. The exploration of topological states in materials is currently focused on metals and semimetals, and their linear band crossing features various topological states, including a nodal point, nodal line and nodal surface. Based on first principles calculations, we have predicted a ternary NdAsPd compound that exhibits multiple topological states of a type-II nodal ring, triply degenerate nodal point and nodal surface states in the absence of spin orbit coupling (SOC) effects. Its band formation mechanism has been analyzed and the corresponding nontrivial drumhead surface and Fermi arc have been confirmed. Under the consideration of SOC, these topological states evolve into a type-II nodal point and type-I nodal line. The remarkable topological diversity in the present material is very rare and can serve as a promising platform upon which to study the rich fermionic states in a single material. This journal is

Intersecting nodal rings in orthorhombic-type BaLi2Sn compound

© The Royal Society of Chemistry 2020. Topological semimetals, such as topological nodal point semimetals (TNPSs) and topological nodal line state semimetals (TNLSs), featuring zero-dimensional (0D) and one-dimensional (1D) topological elements (TEs), respectively, have attracted widespread attention in recent years. In this study,viafirst-principles, we predict that a recently synthesized BaLi2Sn material withPmmnstructure is a TNLS with perfect intersecting nodal rings in thekx= 0 andky= 0 planes when the spin-orbit coupling (SOC) effect is ignored. The intersecting nodal rings were further checked by employing a low-energy effective Hamiltonian near theΓpoint. Surface drum-head-like state was observed, which further confirms the 1D TE in this system. When the SOC is included, although the SOC-induced gaps opened in the band crossing points, a Dirac cross-like surface state was observed for this system. It should be noted that this material was thermally and mechanically stable, and it is hoped that the 1D TE and interesting surface states can be experimentally demonstrated soon

Influence of N2/Ar Flow Ratio on Microstructure and Properties of the AlCrSiN Coatings Deposited by High-Power Impulse Magnetron Sputtering

The cutting properties of tools can be greatly improved by AlCrSiN coatings. The AlCrSiN coatings with nitrogen content in the range of 28.2–56.3 at.% were prepared by varying the N2/Ar flow ratio from 1/4 to 1/1. The influence of N2/Ar flow ratio on composition, microstructure, and mechanical properties, as well as the tribological properties, of the coatings was investigated. With increasing N content, the coating microstructure gradually evolved from single fcc-(Cr,Al)N (200) phase to the mixture of fcc-(Cr,Al)N and hcp-(Cr,Al)N phase, which corresponds to an increased crystallinity within the coatings. The coating presents the highest hardness and best wear resistance for an N2/Ar flow ratio of 1/1, but the film adhesive strength and inner stress decreased obviously with increasing N2/Ar flow ratio, which was attributed to the rapid reduction of particle kinetic energy induced by the obstruction of neutral nitride particles between target and substrates. The highest H3/E*2 value exhibited the lowest wear rate, at 0.81 × 10−14 m3/(N·m), indicating that it had the best resistance to plastic deformation. The main wear mechanisms of the as-deposited coatings were abrasive wear and adhesive wear. The increasing crystallinity of the interior coatings resulted in higher hardness and better tribological behavior with an increase in N2/Ar flow ratio

Surface roughness measuring based on the theory of fractal geometry

Conference Name:2014 International Conference on Design, Manufacturing and Mechatronics, ICDMM 2014. Conference Address: Changsha, Hunan, China. Time:March 21, 2014 - March 23, 2014.Beijing Technology and Business University; Chengdu University; Hebei UniversityConventionally several statistical roughness parameters are used for describing surface roughness. But instruments with different resolutions and scan lengths yield different results of these statistical parameters for the same surface. Due to the limitations of traditional characterizing methods, the fractal characteristic of the rough surface is studied in this paper. A surface roughness measuring instrument is redesigned based on the on the Talysurf 5M for both hardware and software. The signal conditioning process of the inductance sensor is analyzed. The grinding samples measurements indicate that work-piece surface presents fractal characteristic, and larger roughness level Ra corresponds to larger fractal dimension D but smaller characteristic length scale G. The fractal characterization of surface roughness, to some extent, overcomes the deficiencies of conventional evaluation method, and shows higher sensitivity and accuracy. ? (2014) Trans Tech Publications, Switzerland

Bio-syngas methanation towards synthetic natural gas (SNG) over highly active Al2O3-CeO2 supported Ni catalyst

The Al2O3-CeO2 composite supported Ni catalyst was developed for synthetic natural gas (SNG) from bio-syngas methanation. The physico-chemical properties of the Ni-based catalysts were characterized by BET, H-2-TPR, XRD, SEM and TG. The methanation tests showed that Ni/Al2O3-CeO2 presented the highest methanation performances at low temperature (91.6% CO conversion with 92% CH4 selectivity at 350 degrees C) compared with Ni/Al2O3, Ni/ZrO2 and Ni/Al2O3-SiO2, etc. The characterization results indicated that combination of CeO2 with Al2O3 restrained the entering of Ni species into the inside, increasing the Ni species amounts and promoting the dispersion of NiO on the surface of Al2O3-CeO2. In addition, adding CeO2 into Ni/Al2O3 weakened the interaction of NiO-Al2O3 via the strengthening of NiO-CeO2 interaction, promoting the reduction of NiO and formation of active metallic Ni. All of these factors improved the catalytic activity for bio-syngas methanation to SNG and the resistance to carbon deposition for Ni/Al2O3-CeO2. (C) 2015 Elsevier B.V. All rights reserved