215 research outputs found

    Rigid Quantum Monte Carlo Simulations of Condensed Molecular Matter: Water Clusters in the n=2 ―˃ 8 Range

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    The numerical advantage of quantum Monte Carlo simulations of rigid bodies relative to the flexible simulations is investigated for some simple systems. The results show that if high frequency modes in molecular condensed matter are predominantly in the ground state, the convergence of path integral simulations becomes nonuniform. Rigid body quantum parallel tempering simulations are necessary to accurately capture thermodynamic phenomena in the temperature range where the dynamics are influenced by intermolecular degrees of freedom; the stereographic projection path integral adapted for quantum simulations of asymmetric tops is a significantly more efficient strategy compared with Cartesian coordinate simulations for molecular condensed matter under these conditions. The reweighted random series approach for stereographic path integral Monte Carlo is refined and implemented for the quantum simulation of water clusters treated as an assembly of rigid asymmetric tops

    Efficacy and safety of a double-coated paclitaxel-eluting coronary stent: The EUCATAX trial

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    Objectives: The aim of this study was the comparison of a new double-coated paclitaxel-eluting coronary stent with bare-metal stent (BMS) in patients undergoing percutaneous coronary intervention. Background: Stent coating with biodegradable polymers as a platform for elution of drugs has the potential for complete elution of drugs and for decreasing the risk of late complications. Methods: Multicenter randomized trial comparing a paclitaxel-eluting stent (PES) coated with a biodegradable polymer and glycocalyx with the equivalent BMS. We randomly assigned 422 patients with de novo coronary lesions to PES (211 patients) or to BMS (211 patients). Primary end point was target vessel failure (TVF) defined as cardiac death, myocardial infarction, and target vessel revascularization. Clinical secondary end points were target vessel revascularization, target lesion revascularization, stent thrombosis (ST), and major adverse cardiovascular events (MACE). Angiographic secondary end points were late loss and binary restenosis. Results: At 1 year of follow-up, TVF rate was 9.5% in the PES group and 17.1% in the BMS group (P = 0.02), and MACE rate was 10% in PES and 19% in BMS arm (P = 0.009). All other secondary end points were reached but ST. ST rate was low and similar in both study arms. Conclusions: The study shows that patients treated with PES with dual coating technology had significantly lower incidence of TVF and MACE than those treated with BMS design; however, longer follow-up should be necessary to assess true advantages of this technology compared with the previous one.Fil: Rodriguez, Alfredo E.. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Vigo, Cesar F.. Sanatorio del Salvador S. A.; ArgentinaFil: Delacasa, Alejandro. Sanatorio Belgrano; ArgentinaFil: Mieres, Juan. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Fernandez Pereira, Carlos. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Bernardi, Victor. Clinica del Sol;Fil: Bettinoti, Marcelo. Sanatorio Guemes Sociedad Anonima.; ArgentinaFil: Rodriguez Granillo, Gaston Alfredo. Sanatorio "Otamendi y Miroli S.A.". Servicio de Diagnóstico por Imágenes. Departamento de Imágenes en Cardiología. Centro de Investigaciones Cardiovasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Curotto, Valeria. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Rubilar, Bibiana. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Tronge, Jorge. No especifíca;Fil: Palacios, Igor F.. Massachusetts General Hospital; Estados UnidosFil: Antoniucci, David. Careggi Hospital; Itali

    IL-4-secreting CD4+ T cells are crucial to the development of CD8+ T-cell responses against malaria liver stages.

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    CD4+ T cells are crucial to the development of CD8+ T cell responses against hepatocytes infected with malaria parasites. In the absence of CD4+ T cells, CD8+ T cells initiate a seemingly normal differentiation and proliferation during the first few days after immunization. However, this response fails to develop further and is reduced by more than 90%, compared to that observed in the presence of CD4+ T cells. We report here that interleukin-4 (IL-4) secreted by CD4+ T cells is essential to the full development of this CD8+ T cell response. This is the first demonstration that IL-4 is a mediator of CD4/CD8 cross-talk leading to the development of immunity against an infectious pathogen

    Amine functionalization of cholecyst-derived extracellular matrix with generation 1 PAMAM dendrimer

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    This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Biomacromolecules, copyright © American Chemical Society after peer review. To access the final edited and published work, see http://pubs.acs.org/doi/pdf/10.1021/bm701055k.A method to functionalize cholecyst-derived extracellular matrix (CEM) with free amine groups was established in an attempt to improve its potential for tethering of bioactive molecules. CEM was incorporated with Generation-1 polyamidoamine (G1 PAMAM) dendrimer by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide and N-hydroxysuccinimide cross-linking system. The nature of incorporation of PAMAM dendrimer was evaluated using shrink temperature measurements, Fourier transform infrared (FTIR) assessment, ninhydrin assay, and swellability. The effects of PAMAM incorporation on mechanical and degradation properties of CEM were evaluated using a uniaxial mechanical test and collagenase degradation assay, respectively. Ninhydrin assay and FTIR assessment confirmed the presence of increasing free amine groups with increasing quantity of PAMAM in dendrimer-incorporated CEM (DENCEM) scaffolds. The amount of dendrimer used was found to be critical in controlling scaffold degradation, shrink temperature, and free amine content. Cell culture studies showed that fibroblasts seeded on DENCEM maintained their metabolic activity and ability to proliferate in vitro. In addition, fluorescence cell staining and scanning electron microscopy analysis of cell-seeded DENCEM showed preservation of normal fibroblast morphology and phenotype

    Logical Development of the Cell Ontology

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    <p>Abstract</p> <p>Background</p> <p>The Cell Ontology (CL) is an ontology for the representation of <it>in vivo </it>cell types. As biological ontologies such as the CL grow in complexity, they become increasingly difficult to use and maintain. By making the information in the ontology computable, we can use automated reasoners to detect errors and assist with classification. Here we report on the generation of computable definitions for the hematopoietic cell types in the CL.</p> <p>Results</p> <p>Computable definitions for over 340 CL classes have been created using a genus-differentia approach. These define cell types according to multiple axes of classification such as the protein complexes found on the surface of a cell type, the biological processes participated in by a cell type, or the phenotypic characteristics associated with a cell type. We employed automated reasoners to verify the ontology and to reveal mistakes in manual curation. The implementation of this process exposed areas in the ontology where new cell type classes were needed to accommodate species-specific expression of cellular markers. Our use of reasoners also inferred new relationships within the CL, and between the CL and the contributing ontologies. This restructured ontology can be used to identify immune cells by flow cytometry, supports sophisticated biological queries involving cells, and helps generate new hypotheses about cell function based on similarities to other cell types.</p> <p>Conclusion</p> <p>Use of computable definitions enhances the development of the CL and supports the interoperability of OBO ontologies.</p

    DRhigh+CD45RA−-Tregs Potentially Affect the Suppressive Activity of the Total Treg Pool in Renal Transplant Patients

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    Recent studies show that regulatory T cells (Tregs) play an essential role in tolerance induction after organ transplantation. In order to examine whether there are differences in the composition of the total CD4+CD127low+/−FoxP3+- Treg cell pool between stable transplant patients and patients with biopsy proven rejection (BPR), we compared the percentages and the functional activity of the different Treg cell subsets (DRhigh+CD45RA−-Tregs, DRlow+CD45RA−-Tregs, DR−CD45RA−-Tregs, DR−CD45RA+-Tregs). All parameters were determined during the three different periods of time after transplantation (0–30 days, 31–1,000 days, >1,000 days). Among 156 transplant patients, 37 patients suffered from BPR. The most prominent differences between rejecting and non-rejecting patients were observed regarding the DRhigh+CD45RA−-Treg cell subset. Our data demonstrate that the suppressive activity of the total Treg pool strongly depends on the presence of these Treg cells. Their percentage within the total Treg pool strongly decreased after transplantation and remained relatively low during the first year after transplantation in all patients. Subsequently, the proportion of this Treg subset increased again in patients who accepted the transplant and reached a value of healthy non-transplanted subjects. By contrast, in patients with acute kidney rejection, the DRhigh+CD45RA−-Treg subset disappeared excessively, causing a reduction in the suppressive activity of the total Treg pool. Therefore, both the monitoring of its percentage within the total Treg pool and the monitoring of the HLA-DR MFI of the DR+CD45RA−-Treg subset may be useful tools for the prediction of graft rejection

    Impact of the TCR Signal on Regulatory T Cell Homeostasis, Function, and Trafficking

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    Signaling through the T cell antigen receptor (TCR) is important for the homeostasis of naïve and memory CD4+ T cells. The significance of TCR signaling in regulatory T (Treg) cells has not been systematically addressed. Using an Ox40-cre allele that is prominently expressed in Treg cells, and a conditional null allele of the gene encoding p56Lck, we have examined the importance of TCR signaling in Treg cells. Inactivation of p56Lck resulted in abnormal Treg homeostasis characterized by impaired turnover, preferential redistribution to the lymph nodes, loss of suppressive function, and striking changes in gene expression. Abnormal Treg cell homeostasis and function did not reflect the involvement of p56Lck in CD4 function because these effects were not observed when CD4 expression was inactivated by Ox40-cre.The results make clear multiple aspects of Treg cell homeostasis and phenotype that are dependent on a sustained capacity to signal through the TCR

    Malignant B Cells Induce the Conversion of CD4+CD25− T Cells to Regulatory T Cells in B-Cell Non-Hodgkin Lymphoma

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    Recent evidence has demonstrated that regulatory T cells (Treg) were enriched in the tumor sites of patients with B-cell non-Hodgkin lymphoma (NHL). However, the causes of enrichment and suppressive mechanisms need to be further elucidated. Here we demonstrated that CD4+CD25+FoxP3+CD127lo Treg were markedly increased and their phenotypes were different in peripheral blood (PB) as well as bone marrow (BM) from newly diagnosed patients with B-cell NHL compared with those from healthy volunteers (HVs). Involved lymphatic tissues also showed higher frequencies of Treg than benign lymph nodes. Moreover, the frequencies of Treg were significantly higher in involved lymphatic tissues than those from PB as well as BM in the same patients. Suppression mediated by CD4+CD25+ Treg co-cultured with allogeneic CFSE-labeled CD4+CD25− responder cells was also higher in involved lymphatic tissues from B-cell NHL than that mediated by Treg from HVs. In addition, we found that malignant B cells significantly induced FoxP3 expression and regulatory function in CD4+CD25− T cells in vitro. In contrast, normal B cells could not induce the conversion of CD4+CD25− T cells to Treg. We also showed that the PD-1/B7-H1 pathway might play an important role in Treg induction. Taken together, our results suggest that malignant B cells induce the conversion of CD4+CD25− T cells to Treg, which may play a role in the pathogenesis of B-cell NHL and represent a promising therapeutic target

    Chlamydia pneumoniae Infection Induced Allergic Airway Sensitization Is Controlled by Regulatory T-Cells and Plasmacytoid Dendritic Cells

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    Chlamydia pneumoniae (CP) is associated with induction and exacerbation of asthma. CP infection can induce allergic airway sensitization in mice in a dose- and time-dependent manner. Allergen exposure 5 days after a low dose (mild-moderate), but not a high dose (severe) CP infection induces antigen sensitization in mice. Innate immune signals play a critical role in controlling CP infection induced allergic airway sensitization, however these mechanisms have not been fully elucidated. Wild-type, TLR2−/−, and TLR4−/− mice were infected intranasally (i.n.) with a low dose of CP, followed by i.n. exposure to human serum albumin (HSA) and challenged with HSA 2 weeks later. Airway inflammation, immunoglobulins, eosinophils, and goblet cells were measured. Low dose CP infection induced allergic sensitization in TLR2−/− mice, but not in TLR4−/− mice, due to differential Treg responses in these genotypes. TLR2−/− mice had reduced numbers of Tregs in the lung during CP infection while TLR4−/− mice had increased numbers. High dose CP infection resulted in an increase in Tregs and pDCs in lungs, which prevented antigen sensitization in WT mice. Depletion of Tregs or pDCs resulted in allergic airway sensitization. We conclude that Tregs and pDCs are critical determinants regulating CP infection-induced allergic sensitization. Furthermore, TLR2 and TLR4 signaling during CP infection may play a regulatory role through the modulation of Tregs

    More stories on Th17 cells

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    For more than two decades, immunologists have been using the so-called Th1/Th2 paradigm to explain most of the phenomena related to adaptive immunity. the Th1/Th2 paradigm implied the existence of two different, mutually regulated, CD4(+) T helper subsets: Th1 cells, driving cell-mediated immune responses involved in tissue damage and fighting infection against intracellular parasites; and Th2 cells that mediate IgE production and are particularly involved in eosinophilic inflammation, allergy and clearance of helminthic infections. A third member of the T helper set, IL-17-producing CD4(+) T cells, now called Th17 cells, was recently described as a distinct lineage that does not share developmental pathways with either Th1 or Th2 cells. the Th17 subset has been linked to autoimmune disorders, being able to produce IL-17, IL-17F and IL-21 among other inflammatory cytokines. Interestingly, it has been reported that there is not only a cross-regulation among Th1, Th2 and Th17 effector cells but there is also a dichotomy in the generation of Th17 and T regulatory cells. Therefore, Treg and Th17 effector cells arise in a mutually exclusive fashion, depending on whether they are activated in the presence of TGF-beta or TGF-beta plus inflammatory cytokines such as IL-6. This review will address the discovery of the Th17 cells, and recent progress on their development and regulation.Crohn's and Colitis Foundation of AmericaNIHLa Jolla Inst Allergy & Immunol, La Jolla, CA 92037 USAUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilNIH: RO1 AI050265-06Web of Scienc
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