T Cells That Help B Cells in Chronically Inflamed Tissues

Chronically inflamed tissues commonly accrue lymphocyte aggregates that facilitate local T cell-B cell interactions. These aggregates can range from small, loosely arranged lymphocyte clusters to large, organized ectopic lymphoid structures. In some cases, ectopic lymphoid structures develop germinal centers that house prototypical T follicular helper (Tfh) cells with high expression of Bcl6, CXCR5, PD-1, and ICOS. However, in many chronically inflamed tissues, the T cells that interact with B cells show substantial differences from Tfh cells in their surface phenotypes, migratory capacity, and transcriptional regulation. This review discusses observations from multiple diseases and models in which tissue-infiltrating T cells produce factors associated with B cell help, including IL-21 and the B cell chemoattractant CXCL13, yet vary dramatically in their resemblance to Tfh cells. Particular attention is given to the PD-1hi CXCR5− Bcl6low T peripheral helper (Tph) cell population in rheumatoid arthritis, which infiltrates inflamed synovium through expression of chemokine receptors such as CCR2 and augments synovial B cell responses via CXCL13 and IL-21. The factors that regulate CD4+ T cell production of CXCL13 and IL-21 in these settings are also discussed. Understanding the range of T cell populations that can provide help to B cells within chronically inflamed tissues is essential to recognize these cells in diverse inflammatory conditions and to optimize either broad or selective therapeutic targeting of B cell-helper T cells

Single photo-electron trapping, storage, and detection in a one-electron quantum dot

There has been considerable progress in electro-statically emptying, and re-filling, quantum dots with individual electrons. Typically the quantum dot is defined by electrostatic gates on a GaAs/AlGaAs modulation doped heterostructure. We report the filling of such a quantum dot by a single photo-electron, originating from an individual photon. The electrostatic dot can be emptied and reset in a controlled fashion before the arrival of each photon. The trapped photo-electron is detected by a point contact transistor integrated adjacent to the electrostatic potential trap. Each stored photo-electron causes a persistent negative step in the transistor channel current. Such a controllable, benign, single photo-electron detector could allow for information transfer between flying photon qubits and stored electron qubits.Comment: 4 Pages, 5 Figure

InN nanocrystals, nanowires, and nanotubes

Various chemical methods have been utilized to prepare InN nanocrystals, nanowires and nanotubes, which have been characterized by several techniques (see TEM images). The nanostructures exhibit an absorption band in the near-IR region at around 0.7 eV, which rather than being caused by defects, is shown to be an intrinsic and characteristic feature of InN

Human Rad52 binding renders ssDNA unfolded: image and contour length analyses by Atomic Force Microscopy

Atomic force microscopy imaging has been used to study the changes associated with human Rad52 (HsRad52) protein in solution, in dried state as well as following ssDNA (linear and circular) binding. In the dried state, the free protein exists predominantly as a characteristic panoply of novel trifoliate forms. However, in solution, the level of trifoliates diminishes significantly. Height analyses of either form reveal two categories: smaller (~ 3-5 nm) and larger ((~ 10-12 nm) particles, perhaps related to sub-heptameric and heptameric forms respectively. Interestingly, binding of the protein to linear ssDNA smoothly extends and unfolds the naked DNA. Contour length measurements performed on several individual circular ssDNA/nucleoprotein complexes reveal marked (about threefold) extension of naked ssDNA, following HsRad52 binding. We speculate that the alignment of HsRad52 on ssDNA into a smoothly extended and unfolded strand from that of highly compact morphology of naked ssDNA, may have bearing on the recombination function of HsRad52 protein

Effects of temperature and load during hot impression behavior of Cr-Ni stainless steel

Austenitic Stainless steels are majorly used because of their high resistance to aqueous corrosion and high temperature properties. Some major applications of stainless steels at high temperatures include engine and exhaust components in aircrafts, recuperators in steel mills, and pulverized coal injection lances for blast furnaces. In all the above said applications, the components are constantly subjected to loads and high temperatures. This makes the study of their creep behavior very important to decide the life of the component. Cr-Ni stainless steel was used as a starting material, and hot impression creep test was performed on cylindrical samples of 10 mm height and 15 mm diameter for a dwell time of 150 min at two different loads of 84 and 98 MPa and at two different temperatures 450 and 500 °C. The time vs. indentation depth was plotted, and creep rate was calculated in each case. It was observed that with an increase in time, creep rate increased in the primary creep region and remained almost constant in the secondary creep region irrespective of temperature and load. The indentation depth and creep rate increased with an increase in load and temperature

Multiplexed enrichment and genomic profiling of peripheral blood cells reveal subset-specific immune signatures

Specialized immune cell subsets are involved in autoimmune disease, cancer immunity, and infectious disease through a diverse range of functions mediated by overlapping pathways and signals. However, subset-specific responses may not be detectable in analyses of whole blood samples, and no efficient approach for profiling cell subsets at high throughput from small samples is available. We present a low-input microfluidic system for sorting immune cells into subsets and profiling their gene expression. We validate the system’s technical performance against standard subset isolation and library construction protocols and demonstrate the importance of subset-specific profiling through in vitro stimulation experiments. We show the ability of this integrated platform to identify subset-specific disease signatures by profiling four immune cell subsets in blood from patients with systemic lupus erythematosus (SLE) and matched control subjects. The platform has the potential to make multiplexed subset-specific analysis routine in many research laboratories and clinical settings.National Institute of Allergy and Infectious Diseases (U.S.) (Grant U24 AI118668

Interleukin (IL)-1 promotes allogeneic T cell intimal infiltration and IL-17 production in a model of human artery rejection

Interleukin (IL) 1α produced by human endothelial cells (ECs), in response to tumor necrosis factor (TNF) or to co-culture with allogeneic T cells in a TNF-dependent manner, can augment the release of cytokines from alloreactive memory T cells in vitro. In a human–mouse chimeric model of artery allograft rejection, ECs lining the transplanted human arteries express IL-1α, and blocking IL-1 reduces the extent of human T cell infiltration into the artery intima and selectively inhibits IL-17 production by infiltrating T cells. In human skin grafts implanted on immunodeficient mice, administration of IL-17 is sufficient to induce mild inflammation. In cultured cells, IL-17 acts preferentially on vascular smooth muscle cells rather than ECs to enhance production of proinflammatory mediators, including IL-6, CXCL8, and CCL20. Neutralization of IL-17 does not reduce T cell infiltration into allogeneic human artery grafts, but markedly reduces IL-6, CXCL8, and CCL20 expression and selectively inhibits CCR6+ T cell accumulation in rejecting arteries. We conclude that graft-derived IL-1 can promote T cell intimal recruitment and IL-17 production during human artery allograft rejection, and suggest that targeting IL-1 in the perioperative transplant period may modulate host alloreactivity

Photoconductance Quantization in a Single-Photon Detector

We have made a single-photon detector that relies on photoconductive gain in a narrow electron channel in an AlGaAs/GaAs 2-dimensional electron gas. Given that the electron channel is 1-dimensional, the photo-induced conductance has plateaus at multiples of the quantum conductance 2e$^{2}$/h. Super-imposed on these broad conductance plateaus are many sharp, small, conductance steps associated with single-photon absorption events that produce individual photo-carriers. This type of photoconductive detector could measure a single photon, while safely storing and protecting the spin degree of freedom of its photo-carrier. This function is valuable for a quantum repeater that would allow very long distance teleportation of quantum information.Comment: 4 pages, 4 figure

Epitaxial Zn(x)Fe(3-x)O(4) Thin Films: A Spintronic Material with Tunable Electrical and Magnetic Properties

The ferrimagnetic spinel oxide Zn(x)Fe(3-x)O(4) combines high Curie temperature and spin polarization with tunable electrical and magnetic properties, making it a promising functional material for spintronic devices. We have grown epitaxial thin films with 0<=x<=0.9 on MgO(001) substrates with excellent structural properties both in pure Ar atmosphere and an Ar/O2 mixture by laser molecular beam epitaxy. We find that the electrical conductivity and the saturation magnetization can be tuned over a wide range during growth. Our extensive characterization of the films provides a clear picture of the underlying physics of this spinel ferrimagnet with antiparallel Fe moments on the A and B sublattice: (i) Zn substitution removes both Fe3+ moments from the A sublattice and itinerant charge carriers from the B sublattice, (ii) growth in finite oxygen partial pressure generates Fe vacancies on the B sublattice also removing itinerant charge carriers, and (iii) application of both Zn substitution and excess oxygen results in a compensation effect as Zn substitution partially removes the Fe vacancies. A decrease (increase) of charge carrier density results in a weakening (strengthening) of double exchange and thereby a decrease (increase) of conductivity and the saturation magnetization. This scenario is confirmed by the observation that the saturation magnetization scales with the longitudinal conductivity. The combination of tailored films with semiconductor materials such as ZnO in multi-functional heterostructures seems to be particularly appealing.Comment: 13 pages, 8 figures, Hall effect data removed, anti-phase boundary discussion added, accepted for publication in PRB79 (2009