3,002 research outputs found
Quark-Antiquark Energy Density Function applied to Di-Gauge Boson Production at the LHC
In view of the start up of the 14 TeV pp Large Hadron Collider the quark
anti-quark reactions leading to the final states W^+W^-, W^+-Z^0 and Z^0Z^0 are
studied, in the frame workn of the Standard Model (SM), using helicity
amplitudes. The differential and total cross sections are first evaluated in
the parton-parton center of mass system. They are then transformed to their
expected behavior in pp collisions through the parton-parton Energy Density
Functions which are here derived from the known Parton Density Functions of the
proton. In particular the single and joint longitudinal polarizations of the
final state di-bosons are calculated. The effect on these reactions from the
presence of s-channel heavy vector bosons, like the W' and Z', are evaluated to
explore the possibility to utilize the gauge boson pair production as a probe
for these 'Beyond the SM' phenomena.Comment: 15 pages and 8 figures
Simultaneous expression of CD4 and CD8 antigens by a substantial proportion of resting porcine T lymphocytes
The existence of four subpopulations in resting porcine T lymphocytes is documented. In addition to the two known subpopulations which are typified by a mutually exclusive expression of either the CD8 or the CD4 differentiation antigen, CD4-CD8+ and CD4+CD8- T lymphocytes, respectively, two unusual subpopulations were prominent not only in peripheral blood, but also in lymphoid tissues: CD4-CD8- T lymphocytes expressing neither of these antigens and CD4+CD8+ T lymphocytes coexpressing both antigens. While CD4+CD8+ lymphoblasts have been found also in other species, resting T lymphocytes with that phenotype are without precedent among all species analyzed to date. This unique composition of the porcine T lymphocyte population has to be taken into consideration when the swine is used as a large animal model in experimental medicine
Uniting Foes of a Single Nation: Religious Dispute Resolution for India and Pakistan
This article will bring forth the argument that a religious-based dispute resolution mechanism should be employed to, at a bare minimum, build bridges between the two countries that are dominated by Hinduism and Islam. This article is not suggesting that religious-based dispute resolution will be a panacea to the India-Pakistan conflict, but simply a method of putting the countries on a step towards reconciliation. Section II of the article will detail the historical background of the conflict. Section III will highlight existing ADR in both India and Pakistan. Section IV will go over the Islamic perspective on dispute resolution. Section V will review the Hindu method of dispute resolution. Section VI will explain how commonalities between Hindu and Islamic dispute resolution can mitigate the hostilities between the peoples of India and Pakistan. Finally, Section VII will conclude the article
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Revisiting the putative TCR Cα dimerization model through structural analysis
Despite major advances in T cell receptor (TCR) biology and structure, how peptide–MHC complex (pMHC) ligands trigger αβ TCR activation remains unresolved. Two views exist. One model postulates that monomeric TCR–pMHC ligation events are sufficient while a second proposes that TCR–TCR dimerization in cis via Cα domain interaction plus pMHC binding is critical. We scrutinized 22 known TCR/pMHC complex crystal structures, and did not find any predicted molecular Cα–Cα contacts in these crystals that would allow for physiological TCR dimerization. Moreover, the presence of conserved glycan adducts on the outer face of the Cα domain preclude the hypothesized TCR dimerization through the Cα domain. Observed functional consequences of Cα mutations are likely indirect, with TCR microclusters at the immunological synapse driven by TCR transmembrane/cytoplasmic interactions via signaling molecules, scaffold proteins, and/or cytoskeletal elements
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Molecular T Cell Biology – Basic and Translational Challenges in the Twenty-First Century
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New approaches to eliciting protective immunity through T cell repertoire manipulation: the concept of thymic vaccination
Conventional vaccines afford protection against infectious diseases by expanding existing pathogen-specific peripheral lymphocytes, both CD8 cytotoxic effector (CTL) and CD4 helper T cells. The latter induce B cell maturation and antibody production. As a consequence, lymphocytes within the memory pool are poised to rapidly proliferate at the time of a subsequent infection. The "thymic vaccination" concept offers a novel way to alter the primary T cell repertoire through exposure of thymocytes to altered peptide ligands (APL) with reduced T cell receptor (TCR) affinity relative to cognate antigens recognized by those same TCRs. Thymocyte maturation (i.e. positive selection) is enhanced by low affinity interaction between a TCR and an MHC-bound peptide in the thymus and subsequent emigration of mature cells into the peripheral T lymphocyte pool follows. In principal, such variants of antigens derived from infectious agents could be utilized for peptide-driven maturation of thymocytes bearing pathogen-specific TCRs. To test this idea, APLs of gp(33–41), a D(b)-restricted peptide derived from the lymphocytic choriomeningitis virus (LCMV) glycoprotein, and of VSV8, a K(b)-restricted peptide from the vesicular stomatitis virus (VSV) nucleoprotein, have been designed and their influence on thymic maturation of specific TCR-bearing transgenic thymocytes examined in vivo using irradiation chimeras. Injection of APL resulted in positive selection of CD8 T cells expressing the relevant viral specificity and in the export of those virus-specific CTL to lymph nodes without inducing T cell proliferation. Thus, exogenous APL administration offers the potential of expanding repertoires in vivo in a manner useful to the organism. To efficiently peripheralize antigen-specific T cells, concomitant enhancement of mechanisms promoting thymocyte migration appears to be required. This commentary describes the rationale for thymic vaccination and addresses the potential prophylactic and therapeutic applications of this approach for treatment of infectious diseases and cancer. Thymic vaccination-induced peptide-specific T cells might generate effective immune protection against disease-causing agents, including those for which no effective natural protection exists
PEPVAC: a web server for multi-epitope vaccine development based on the prediction of supertypic MHC ligands
Prediction of peptide binding to major histocompatibility complex (MHC) molecules is a basis for anticipating T-cell epitopes, as well as epitope discovery-driven vaccine development. In the human, MHC molecules are known as human leukocyte antigens (HLAs) and are extremely polymorphic. HLA polymorphism is the basis of differential peptide binding, until now limiting the practical use of current epitope-prediction tools for vaccine development. Here, we describe a web server, PEPVAC (Promiscuous EPitope-based VACcine), optimized for the formulation of multi-epitope vaccines with broad population coverage. This optimization is accomplished through the prediction of peptides that bind to several HLA molecules with similar peptide-binding specificity (supertypes). Specifically, we offer the possibility of identifying promiscuous peptide binders to five distinct HLA class I supertypes (A2, A3, B7, A24 and B15). We estimated the phenotypic population frequency of these supertypes to be 95%, regardless of ethnicity. Targeting these supertypes for promiscuous peptide-binding predictions results in a limited number of potential epitopes without compromising the population coverage required for practical vaccine design considerations. PEPVAC can also identify conserved MHC ligands, as well as those with a C-terminus resulting from proteasomal cleavage. The combination of these features with the prediction of promiscuous HLA class I ligands further limits the number of potential epitopes. The PEPVAC server is hosted by the Dana-Farber Cancer Institute at the site
Recognition and classification of histones using support vector machine
Histones are DNA-binding proteins found in the chromatin of all eukaryotic cells. They are highly conserved and can be grouped into five major classes: H1/H5, H2A, H2B, H3, and H4. Two copies of H2A, H2B, H3, and H4 bind to about 160 base pairs of DNA forming the core of the nucleosome (the repeating structure of chromatin) and H1/H5 bind to its DNA linker sequence. Overall, histones have a high arginine/lysine content that is optimal for interaction with DNA. This sequence bias can make the classification of histones difficult using standard sequence similarity approaches. Therefore, in this paper, we applied support vector machine (SVM) to recognize and classify histones on the basis of their amino acid and dipeptide composition. On evaluation through a five-fold cross-validation, the SVM-based method was able to distinguish histones from nonhistones (nuclear proteins) with an accuracy around 98%. Similarly, we obtained an overall >95% accuracy in discriminating the five classes of histones through the application of 1-versus-rest (1-v-r) SVM. Finally, we have applied this SVM-based method to the detection of histones from whole proteomes and found a comparable sensitivity to that accomplished by hidden Markov motifs (HMM) profiles
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