Bulk Memory Research Articles

P034 Peripheral immune cell activity and biopsy gene expression in chronic pouchitis patients treated with tofacitinib: early induction results from the STOPit trial

Abstract Background The Study of TOfacitinib for the treatment of chronic PouchITis (STOPit) is an investigator-initiated, open-label induction, double-blind, placebo-controlled, maintenance withdrawal study to determine the effectiveness of tofacitinib at inducing and maintaining remission in patients with chronic pouchitis. In this interim assessment, we evaluated blood samples and biopsy gene expression collected during the open-label induction period to discover biomarkers of initial clinical response. Methods We collected blood (n = 10 pairs, n = 5 non-responders) and biopsies (n = 21 pairs, n = 9 non-responders) at baseline and after 8 weeks of tofacitinib induction therapy (all participants received 10 mg twice daily induction). We classified patients as responders if they achieved a decrease of ≥ 2 in their modified pouchitis disease activity index after 8 weeks. Bulk peripheral blood mononuclear cells (PBMCs) and memory CD4+ T cells (TMEMs) were isolated from whole blood samples. Cytokines induced by stimulation in the presence or absence of tofacitinib were assessed in culture supernatants by bead array (PBMCs stimulated with PMA/Io or LPS, TMEMs stimulated with CD3/CD28 tetramer). Gene expression was measured in biopsies by qPCR in the pouch and pre-pouch ileum at both time points. Results At baseline, non-responders produced more IL-17 from both their PBMCs stimulated with PMA/Io and TMEMs stimulated with tetramer than responders, but responders secreted more IL-12p70, MCP, IL-10 and IL-8. Tofacitinib inhibited stimulation-induced IL-10 and IL-6 secretion in PBMCs in both responders and non-responders but failed to reduce IFNγ and TNF secretion selectively in non-responders only. All cytokine responses investigated in TMEMs, including IFNγ and TNF, were inhibited by tofacitinib in both responders and non-responders, suggesting the PBMC cell type refractory to inhibition with tofacitinib in non-responders is not TMEMs. Baseline biopsy ileal gene expression of IL18, HES1 and CXCL10 was decreased in responders compared to non-responders, while MMP7 was increased. Clinical response to tofacitinib led to a reduction in pouch expression of GLIS3, G0S2 and WNT5a from baseline to week 8 whereas these genes were unchanged or increased in non-responders. Conclusion Baseline functional immune cell responses and biopsy gene expression may discriminate chronic pouchitis patients' response to tofacitinib therapy and point to a mechanism underlying non-responsiveness. Recruitment for this trial is ongoing, allowing us to bolster and expand our findings with increasing sample sizes.

Elimination Noise from Image Using Machine Learning Techniques

The Image Processing system is mostly used because of their easy accessibility of powerful personal computers, bulk memory machines with graphics software and others visual application. Of “Image Processing” is applied in a number of applications. These include in area of Remote Sensing in GIS application, Medical Imaging Processing for patient care application, Forensic Studies, Textiles engineering and design, Material science, Military Research, Film industry application, and Document processing, Graphic arts. An image is defined as an array, or a matrix, square pixel arranged in rows and columns. Many image-processing procedures involve making the image as a two-dimensional signal and applying standard signal processing techniques to it. Image processing can be defined by means of a ‘digital image processing’’. The pitch of ‘digital image processing’ states to ‘processing digital’ images through channels of a computer. In this paper Image de-noising through K-SVD algorithm is presented by taking the RGB color with 256*256 sizes 24 bit standardize image.

Ultrafast response of Ge2Sb2Te5 nanoparticles: The benefits of low energy amorphization switching with the same read/write speed of bulk memories

We investigate the ultrafast response of crystalline Ge2Sb2Te5 nanoparticles (NPs) below the phase transformation threshold fluence. The observed rapid change of the optical response and the presence of coherent optical phonons are consistent with the relaxation dynamics in bulk Ge2Sb2Te5 films and, more importantly, occur within the same ultrafast timescales. We conclude that the benefit of the lower energy consumption of memories based on Ge-Sb-Te (GST) NPs aggregates, demonstrated by Casarin et al. (2018), occurs with no disadvantage, as the read/write speed can be as fast as in bulk GSTs.

Logical Blocks for Fault-Tolerant Topological Quantum Computation

Logical gates constitute the building blocks of fault-tolerant quantum computation. While quantum error-corrected memories have been extensively studied in the literature, explicit constructions and detailed analyses of thresholds and resource overheads of universal logical gate sets have so far been limited. In this paper, we present a comprehensive framework for universal fault-tolerant logic motivated by the combined need for platform-independent logical gate definitions, flexible and scalable tools for numerical analysis, and exploration of novel schemes for universal logic that improve resource overheads. Central to our framework is the description of logical gates holistically in a way which treats space and time on a similar footing. Focusing on schemes based on surface codes, we introduce explicit, but platform-independent representations of topological logic gates -- called logical blocks -- and generate new, overhead-efficient methods for universal quantum computation. As a specific example, we propose fault-tolerant schemes based on surface codes concatenated with more general low-density parity check (LDPC) codes. The logical blocks framework enables a convenient mapping from an abstract description of the logical gate to a precise set of physical instructions for both circuit-based and fusion-based quantum computation (FBQC). Using this, we numerically simulate a surface-code-based universal gate set implemented with FBQC, and verify that their thresholds are consistent with the bulk memory threshold. We find that boundaries, defects, and twists can significantly impact the logical error rate scaling, with periodic boundary conditions potentially halving the resource requirements. Motivated by the favorable logical error rates for boundaryless computation, we introduce a novel computational scheme based on the teleportation of twists that may offer further resource reductions.

Quantification of T-cell dynamics during latent cytomegalovirus infection in humans.

Cytomegalovirus (CMV) infection has a major impact on the T-cell pool, which is thought to be associated with ageing of the immune system. The effect on the T-cell pool has been interpreted as an effect of CMV on non-CMV specific T-cells. However, it remains unclear whether the effect of CMV could simply be explained by the presence of large, immunodominant, CMV-specific memory CD8+ T-cell populations. These have been suggested to establish through gradual accumulation of long-lived cells. However, little is known about their maintenance. We investigated the effect of CMV infection on T-cell dynamics in healthy older adults, and aimed to unravel the mechanisms of maintenance of large numbers of CMV-specific CD8+ T-cells. We studied the expression of senescence, proliferation, and apoptosis markers and quantified the in vivo dynamics of CMV-specific and other memory T-cell populations using in vivo deuterium labelling. Increased expression of late-stage differentiation markers by CD8+ T-cells of CMV+ versus CMV- individuals was not solely explained by the presence of large, immunodominant CMV-specific CD8+ T-cell populations. The lifespans of circulating CMV-specific CD8+ T-cells did not differ significantly from those of bulk memory CD8+ T-cells, and the lifespans of bulk memory CD8+ T-cells did not differ significantly between CMV- and CMV+ individuals. Memory CD4+ T-cells of CMV+ individuals showed increased expression of late-stage differentiation markers and decreased Ki-67 expression. Overall, the expression of senescence markers on T-cell populations correlated positively with their expected in vivo lifespan. Together, this work suggests that i) large, immunodominant CMV-specific CD8+ T-cell populations do not explain the phenotypical differences between CMV+ and CMV- individuals, ii) CMV infection hardly affects the dynamics of the T-cell pool, and iii) large numbers of CMV-specific CD8+ T-cells are not due to longer lifespans of these cells.

PHENOMENOLOGICAL MODELING OF VOLUME NANOMATERIALS WITH FORM MEMORY

The paper presents a phenomenological approach to modeling bulk memory nanomaterials form. A phenomenological model has been proposed that can be applied to model the behavior of nanomaterials with shape memory properties. The study of shape memory alloys as functionally inhomogeneous materials with the properties of pseudo-elastic-plasticity is presented. The phenomenological model is confirmed by experimental data. Tables of diagrams for different temperatures of alloys with shape memory are given.Key words: modeling, functionally inhomogeneous materials, nanomaterials, phenomenological approach, large deformations

CD3 and CD8 coreceptor down-modulation are inversely associated with CD8 T cell functional avidity in humans

Abstract This study investigated the function of memory CD8 T cells in HIV-infected people durably suppressed on antiretroviral therapy (HIV+ cART). We assessed bulk and virus-specific memory CD8 T cells in HIV+ cART and HIV-seronegative individuals (HIV−) by flow cytometry. We observed a population of CD3+ CD8dim CD14− CD16− (CD8dim) T cells that was expanded as a percentage of total CD8 T cells in both HIV− and CMV-seropositive individuals. Bulk memory CD8dim T cells expressed significantly higher CD69 and less MHC Class I and CD127 ex vivo than CD8bright T cells, suggesting recent activation. CD8dim T cells expressed less GLUT1 and PGC-1α and took up less glucose (2-NBDG) and lipid (Bodipy) than CD8bright T cells, indicating relatively lower metabolic activity. Multimer reactivity was used to examine CMV-, EBV- and HIV-specific CD8 T cells ex vivo. Virus-specific populations were consistently CD8high. However, after peptide stimulation, antigen-specific CD8 T cells down-regulated CD3 and CD8. CMV-specific CD8 T cells down-regulated CD3 and CD8 more than HIV-specific cells. CD3 and CD8 downregulation were strongly correlated with the functional avidity of the response. A strong correlation between GLUT1 down-regulation and CD8 down-regulation was also observed, suggesting an association between CD8 expression and metabolic activity. These results suggest that the expanded CD8dim population in HIV+ cART individuals, who are >90% CMV-seropositive, may be driven by ongoing activation of high-avidity CMV-specific CD8 T cells. They also suggest that different virus-specific CD8 T cell populations differentially downregulate components of the TCR complex and metabolism after antigen stimulation, possibly to avoid excessive activation.

Accelerated bulk memory operations on heterogeneous multi-core systems

A traditional fixed-function graphics accelerator has evolved into a programmable general-purpose graphics processing unit over the past few years, the general-purpose computing on GPU (GPGPU). Recently, revolutionary measures have been taken along this direction: an integrated GPU, i.e., CPUs and GPUs are integrated into the same package or even into the same die. However, considering a system-on-chip, the GPU takes up considerable silicon resources, but when running non-graphical workloads or non-GPGPU applications it is likely that overall system performance will not be affected. This paper presents a novel approach to accelerate conventional operations that are normally performed on CPUs, which are bulk memory operations such as memcpy or memcmp, using an integrated GPU. Offloading bulk memory operations to the GPU has many benefits: (i) The throughput GPU outperforms the CPU in bulk memory operations; (ii) for on-die GPUs with unified cache between the GPU and the CPU, the CPU can utilize the GPU private cache to store the moved data and reduce the CPU cache bottleneck; (iii) additional lightweight hardware can also support asynchronous offloads; and (iv) unlike the prior art using a dedicated hardware copy engine (e.g., DMA), our approach utilizes as much GPU hardware resources as possible. The performance results based on our solution showed that offloaded bulk memory operations outperform CPU up to 4.3 times faster on micro-benchmarks while using fewer resources. Using eight real-world applications and a cycle-based full-system simulation environment, five of eight applications showed about 30% speedup and two applications showed about 20% speedup.

Optimisation of ex vivo memory B cell expansion/differentiation for interrogation of rare peripheral memory B cell subset responses.

Background: Human memory B cells play a vital role in the long-term protection of the host from pathogenic re-challenge. In recent years the importance of a number of different memory B cell subsets that can be formed in response to vaccination or infection has started to become clear. To study memory B cell responses, cells can be cultured ex vivo, allowing for an increase in cell number and activation of these quiescent cells, providing sufficient quantities of each memory subset to enable full investigation of functionality. However, despite numerous papers being published demonstrating bulk memory B cell culture, we could find no literature on optimised conditions for the study of memory B cell subsets, such as IgM + memory B cells. Methods: Following a literature review, we carried out a large screen of memory B cell expansion conditions to identify the combination that induced the highest levels of memory B cell expansion. We subsequently used a novel Design of Experiments approach to finely tune the optimal memory B cell expansion and differentiation conditions for human memory B cell subsets. Finally, we characterised the resultant memory B cell subpopulations by IgH sequencing and flow cytometry. Results: The application of specific optimised conditions induce multiple rounds of memory B cell proliferation equally across Ig isotypes, differentiation of memory B cells to antibody secreting cells, and importantly do not alter the Ig genotype of the stimulated cells. Conclusions: Overall, our data identify a memory B cell culture system that offers a robust platform for investigating the functionality of rare memory B cell subsets to infection and/or vaccination.

Referee report. For: Optimisation of ex vivo memory B cell expansion/differentiation for interrogation of rare peripheral memory B cell subset responses [version 1; referees: 1 approved with reservations

Background: Human memory B cells play a vital role in the long-term protection of the host from pathogenic re-challenge. In recent years the importance of a number of different memory B cell subsets that can be formed in response to vaccination or infection has started to become clear. To study memory B cell responses, cells can be cultured ex vivo, allowing for an increase in cell number and activation of these quiescent cells, providing sufficient quantities of each memory subset to enable full investigation of functionality. However, despite numerous papers being published demonstrating bulk memory B cell culture, we could find no literature on optimised conditions for the study of memory B cell subsets, such as IgM + memory B cells. Methods: Following a literature review, we carried out a large screen of memory B cell expansion conditions to identify the combination that induced the highest levels of memory B cell expansion. We subsequently used a novel Design of Experiments approach to finely tune the optimal memory B cell expansion and differentiation conditions for human memory B cell subsets. Finally, we characterised the resultant memory B cell subpopulations by IgH sequencing and flow cytometry. Results: The application of specific optimised conditions induce multiple rounds of memory B cell proliferation equally across Ig isotypes, differentiation of memory B cells to antibody secreting cells, and importantly do not alter the Ig genotype of the stimulated cells. Conclusions: Overall, our data identify a memory B cell culture system that offers a robust platform for investigating the functionality of rare memory B cell subsets to infection and/or vaccination.

Optimisation of ex vivo memory B cell expansion/differentiation for interrogation of rare peripheral memory B cell subset responses

Background:Human memory B cells play a vital role in the long-term protection of the host from pathogenic re-challenge. In recent years the importance of a number of different memory B cell subsets that can be formed in response to vaccination or infection has started to become clear. To study memory B cell responses, cells can be culturedex vivo,allowing for an increase in cell number and activation of these quiescent cells, providing sufficient quantities of each memory subset to enable full investigation of functionality. However, despite numerous papers being published demonstrating bulk memory B cell culture, we could find no literature on optimised conditions for the study of memory B cell subsets, such as IgM+memory B cells.Methods:Following a literature review, we carried out a large screen of memory B cell expansion conditions to identify the combination that induced the highest levels of memory B cell expansion. We subsequently used a novel Design of Experiments approach to finely tune the optimal memory B cell expansion and differentiation conditions for human memory B cell subsets. Finally, we characterised the resultant memory B cell subpopulations by IgH sequencing and flow cytometry.Results:The application of specific optimised conditions induce multiple rounds of memory B cell proliferation equally across Ig isotypes, differentiation of memory B cells to antibody secreting cells, and importantly do not alter the Ig genotype of the stimulated cells. Conclusions:Overall, our data identify a memory B cell culture system that offers a robust platform for investigating the functionality of rare memory B cell subsets to infection and/or vaccination.

Selective Expression of CCR10 and CXCR3 by Circulating Human Herpes Simplex Virus-Specific CD8 T Cells

Herpes simplex virus (HSV) infection is restricted to epithelial cells and neurons and is controlled by CD8 T cells. These cells both traffic to epithelial sites of recurrent lytic infection and to ganglia and persist at the dermal-epidermal junction for up to 12 weeks after lesion resolution. We previously showed that cutaneous lymphocyte-associated antigen (CLA), a functional E-selectin ligand (ESL), is selectively expressed on circulating HSV-2-specific CD8 T cells. CLA/ESL mediates adhesion of T cells to inflamed vascular endothelium. Later stages in T-cell homing involve chemokines (Ch) and lymphocyte chemokine receptors (ChR) for vascular wall arrest and diapedesis. Several candidate ChR have been implicated in skin homing. We measured cell surface ChR on HSV-specific human peripheral blood CD8 T cells and extended our studies to HSV-1. We observed preferential cell surface expression of CCR10 and CXCR3 by HSV-specific CD8 T cells compared to CD8 T cells specific for control viruses, Epstein-Barr virus (EBV) and cytomegalovirus (CMV), and compared to bulk memory CD8 T cells. CXCR3 ligand mRNA levels were selectively increased in skin biopsy specimens from persons with recurrent HSV-2, while the mRNA levels of the CCR10 ligand CCL27 were equivalent in lesion and control skin. Our data are consistent with a model in which CCL27 drives baseline recruitment of HSV-specific CD8 T cells expressing CCR10, while interferon-responsive CXCR3 ligands recruit additional cells in response to virus-driven inflammation.IMPORTANCE HSV-2 causes very localized recurrent infections in the skin and genital mucosa. Virus-specific CD8 T cells home to the site of recurrent infection and participate in viral clearance. The exit of T cells from the blood involves the use of chemokine receptors on the T-cell surface and chemokines that are present in infected tissue. In this study, circulating HSV-2-specific CD8 T cells were identified using specific fluorescent tetramer reagents, and their expression of several candidate skin-homing-associated chemokine receptors was measured using flow cytometry. We found that two chemokine receptors, CXCR3 and CCR10, are upregulated on HSV-specific CD8 T cells in blood. The chemokines corresponding to these receptors are also expressed in infected tissues. Vaccine strategies to prime CD8 T cells to home to HSV lesions should elicit these chemokine receptors if possible to increase the homing of vaccine-primed cells to sites of infection.

Composition, Constitution and Phase Transformation Behavior in Thin-Film and Bulk Ti–Ni–Y

Advanced engineering applications require new and improved shape memory alloys in bulk and thin-film form. While many Ti–Ni-based systems have been studied so far, the Ti–Ni–Y materials system was not studied in detail concerning its bulk and thin-film shape memory properties. For this reason, a Ti–Ni–Y thin-film materials library focussing on compositions close to Ni50Ti50 was fabricated by combinatorial magnetron sputtering. This library was characterized by high-throughput methods and the compositional range where phase transformations occur was identified. Ti–Ni–Y thin films exhibit a very narrow hysteresis width ∆T and allow to precisely adjust ∆T. Based on the promising results of Ti–Ni–Y thin films, which can be directly applied in microsystems, bulk alloys were fabricated in order to explore how thin-film and bulk properties of different Ti–Ni–Y compositions correlate. It turned out that Ti–Ni–Y bulk materials show different phase transformation properties compared to thin films, most importantly higher ∆T. The differences between thin-film and bulk material are discussed.

Nuclear PKC-θ facilitates rapid transcriptional responses in human memory CD4+ T cells through p65 and H2B phosphorylation.

ABSTRACTMemory T cells are characterized by their rapid transcriptional programs upon re-stimulation. This transcriptional memory response is facilitated by permissive chromatin, but exactly how the permissive epigenetic landscape in memory T cells integrates incoming stimulatory signals remains poorly understood. By genome-wide ChIP-sequencing ex vivo human CD4+ T cells, here, we show that the signaling enzyme, protein kinase C theta (PKC-θ) directly relays stimulatory signals to chromatin by binding to transcriptional-memory-responsive genes to induce transcriptional activation. Flanked by permissive histone modifications, these PKC-enriched regions are significantly enriched with NF-κB motifs in ex vivo bulk and vaccinia-responsive human memory CD4+ T cells. Within the nucleus, PKC-θ catalytic activity maintains the Ser536 phosphorylation on the p65 subunit of NF-κB (also known as RelA) and can directly influence chromatin accessibility at transcriptional memory genes by regulating H2B deposition through Ser32 phosphorylation. Furthermore, using a cytoplasm-restricted PKC-θ mutant, we highlight that chromatin-anchored PKC-θ integrates activating signals at the chromatin template to elicit transcriptional memory responses in human memory T cells.

Altered Memory T-Cell Responses to Bacillus Calmette-Guerin and Tetanus Toxoid Vaccination and Altered Cytokine Responses to Polyclonal Stimulation in HIV-Exposed Uninfected Kenyan Infants.

Implementation of successful prevention of mother-to-child transmission of HIV strategies has resulted in an increased population of HIV-exposed uninfected (HEU) infants. HEU infants have higher rates of morbidity and mortality than HIV-unexposed (HU) infants. Numerous factors may contribute to poor health in HEU infants including immunological alterations. The present study assessed T-cell phenotype and function in HEU infants with a focus on memory Th1 responses to vaccination. We compared cross-sectionally selected parameters at 3 and 12 months of age in HIV-exposed (n = 42) and HU (n = 28) Kenyan infants. We measured ex vivo activated and bulk memory CD4 and CD8 T-cells and regulatory T-cells by flow cytometry. In addition, we measured the magnitude, quality and memory phenotype of antigen-specific T-cell responses to Bacillus Calmette-Guerin and Tetanus Toxoid vaccine antigens, and the magnitude and quality of the T cell response following polyclonal stimulation with staphylococcal enterotoxin B. Finally, the influence of maternal disease markers on the immunological parameters measured was assessed in HEU infants. Few perturbations were detected in ex vivo T-cell subsets, though amongst HEU infants maternal HIV viral load positively correlated with CD8 T cell immune activation at 12 months. Conversely, we observed age-dependent differences in the magnitude and polyfunctionality of IL-2 and TNF-α responses to vaccine antigens particularly in Th1 cells. These changes mirrored those seen following polyclonal stimulation, where at 3 months, cytokine responses were higher in HEU infants compared to HU infants, and at 12 months, HEU infant cytokine responses were consistently lower than those seen in HU infants. Finally, reduced effector memory Th1 responses to vaccine antigens were observed in HEU infants at 3 and 12 months and higher central memory Th1 responses to M. tuberculosis antigens were observed at 3 months only. Long-term monitoring of vaccine efficacy and T-cell immunity in this vulnerable population is warranted.

High diversity in the TCR repertoire of GAD65 autoantigen-specific human CD4+ T cells.

Autoreactive CD4(+) T cells are an essential feature of type 1 diabetes mellitus. We applied single-cell TCR α- and β-chain sequencing to peripheral blood GAD65-specific CD4(+) T cells, and TCR α-chain next-generation sequencing to bulk memory CD4(+) T cells to provide insight into TCR diversity in autoimmune diabetes mellitus. TCRs obtained for 1650 GAD65-specific CD4(+) T cells isolated from GAD65 proliferation assays and/or GAD65 557I tetramer staining in 6 patients and 10 islet autoantibody-positive children showed large diversity with 1003 different TCRs identified. TRAV and TRBV gene usage was broad, and the TRBV5.1 gene was most prominent within the GAD65 557I tetramer(+) cells. Limited overlap (<5%) was observed between TCRs of GAD65-proliferating and GAD65 557I tetramer(+) CD4(+) T cells. Few TCRs were repeatedly found in GAD65-specific cells at different time points from individual patients, and none was seen in more than one subject. However, single chains were often shared between patients and used in combination with different second chains. Next-generation sequencing revealed a wide frequency range (<0.00001-1.62%) of TCR α-chains corresponding to GAD65-specific T cells. The findings support minor selection of genes and TCRs for GAD65-specific T cells, but fail to provide strong support for TCR-targeted therapies.

Human antigen‐specific CD4+CD25+CD134+CD39+ T cells are enriched for regulatory T cells and comprise a substantial proportion of recall responses

Human Ag-specific CD4(+) Tcells can be detected by their dual expression of CD134 (OX40) and CD25 after a 44 hours stimulation with cognate Ag. We show that surface expression of CD39 on Ag-specific cells consistently identifies a substantial population of CD4(+) CD25(+) CD134(+) CD39(+) Tcells that have a Treg-cell-like phenotype and mostly originate from bulk memory CD4(+) CD45RO(+) CD127(low) CD25(high) CD39(+) Treg cells. Viable, Ag-specific CD25(+) CD134(+) CD39(+) Tcells could be expanded in vitro as cell lines and clones, and retained high Forkhead Box Protein 3, CTLA-4 and CD39 expression, suppressive activity and Ag specificity. We also utilised this combination of cell surface markers to measure HIV-Gag responses in HIV(+) patients before and after anti-retroviral therapy (ART). Interestingly, we found that the percentage of CD39(-) cells within baseline CD4(+) T-cell responses to HIV-Gag was negatively correlated with HIV viral load pre-ART and positively correlated with CD4(+) T-cell recovery over 96 weeks of ART. Collectively, our data show that Ag-specific CD4(+) CD25(+) CD134(+) CD39(+) Tcells are highly enriched for Treg cells, form a large component of recall responses and maintain a Treg-cell-like phenotype upon in vitro expansion. Identification and isolation of these cells enables the role of Treg cells in memory responses to be further defined and provides a development pathway for novel therapeutics.

Evolution of microstructure during shape memory cycling of a main-chain liquid crystalline elastomer

The field of shape memory polymers (SMPs) has been dominated by polymeric systems whose fixing mechanism is based on crystallization or vitrification of the constituent chains, rendering such systems stiff in comparison to elastomers, gels, and living tissues. Previously, we reported the synthesis and characterization of main-chain, segmented liquid crystalline elastomers (LCEs) that exhibit both bulk and surface shape memory effects. These LCEs have excellent shape fixing and recovery characteristics with compositionally-dependent transition temperatures that determine the fixing and recovery critical temperatures. Synthesis of the soft shape memory LCEs proceeded by hydrosilylation-linking of poly(dimethylsiloxane) oligomers with mesogenic dienes of two compositions and a tetravinyl crosslinker. The present report describes microstructural changes during ex situ shape memory deformation and recovery of one such LCE. Wide-angle x-ray scattering showed that, once a critical deformation stress was reached, the microstructure of the fixed, oriented LCEs was independent of the stress applied above the clearing (isotropization) transition. Stepped recovery of the fixed, oriented LCE showed additional intermediate microstructures, however. Recovery was shown to proceed through changes in both the smectic layer thickness and chevron architecture, while mesogen tilt angle remained unchanged. The mechanical and microstructural studies described herein give deeper insight to shape memory fixing and recovery mechanisms of these unique materials, which offer potential for exploitation in areas such as cell and tissue culture, microcontact printing, and microfluidics.

T-cell immunity and cytokine production in cosmonauts after long-duration space flights

Long-duration spaceflight effects on T-cell immunity and cytokine production were studied in 12 Russian cosmonauts flown onto the International Space Station. Specific assays were performed before launch and after landing and included analysis of peripheral leukocyte distribution, analysis of T-cell phenotype, expression of activation markers, apoptosis, proliferation of T cells in response to a mitogen, concentrations of cytokines in supernatants of cell cultures. Statistically significant increase was observed in leukocytes’, lymphocytes’, monocytes’ and granulocytes’ total number, increase in percentage and absolutely number of CD3+CD4+-cells, CD4+CD45RA+-cells and CD4+CD45RA+/CD4+CD45RО+ ratio, CD4+CD25+Bright regulatory cells (p<0,05) in peripheral blood after landing. T-lymphocytes’ capacity to present CD69 and CD25 on its own surfaces was increased for the majority of crewmembers. Analysis of T-cell response to PHA-stimulation in vitro revealed there were some trends toward reduced proliferation of stimulated T-lymphocytes. There was an apparent post flight decrease in secreted IFN-g for the majority of crewmembers and in most instances there was elevation in secreted IL-10. It revealed depression of IFN-g/IL-10 ratio after flight. Correlation analysis according to Spearman’s rank correlation test established significant positive correlations (p<0.05) between cytokine production and T-cell activation (CD25+, CD38+) and negative correlation (p<0.05) between cytokine production and number of bulk memory CD4+T-cells (CD45RO+). Thus, these results suggest that T-cell dysfunction can be conditioned by cytokine dysbalance and could lead to development of disease after long-duration space flights.

Cytotoxic T lymphocytes established by seasonal human influenza cross-react against 2009 pandemic H1N1 influenza virus.

While few children and young adults have cross-protective antibodies to the pandemic H1N1 2009 (pdmH1N1) virus, the illness remains mild. The biological reasons for these epidemiological observations are unclear. In this study, we demonstrate that the bulk memory cytotoxic T lymphocytes (CTLs) established by seasonal influenza viruses from healthy individuals who have not been exposed to pdmH1N1 can directly lyse pdmH1N1-infected target cells and produce gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha). Using influenza A virus matrix protein 1 (M1(58-66)) epitope-specific CTLs isolated from healthy HLA-A2(+) individuals, we further found that M1(58-66) epitope-specific CTLs efficiently killed both M1(58-66) peptide-pulsed and pdmH1N1-infected target cells ex vivo. These M1(58-66)-specific CTLs showed an effector memory phenotype and expressed CXCR3 and CCR5 chemokine receptors. Of 94 influenza A virus CD8 T-cell epitopes obtained from the Immune Epitope Database (IEDB), 17 epitopes are conserved in pdmH1N1, and more than half of these conserved epitopes are derived from M1 protein. In addition, 65% (11/17) of these epitopes were 100% conserved in seasonal influenza vaccine H1N1 strains during the last 20 years. Importantly, seasonal influenza vaccination could expand the functional M1(58-66) epitope-specific CTLs in 20% (4/20) of HLA-A2(+) individuals. Our results indicated that memory CTLs established by seasonal influenza A viruses or vaccines had cross-reactivity against pdmH1N1. These might explain, at least in part, the unexpected mild pdmH1N1 illness in the community and also might provide some valuable insights for the future design of broadly protective vaccines to prevent influenza, especially pandemic influenza.