The Polymerization of Ring Substituted Styrenes and the Degradation of Their Polymers

Abstract Not Provided

Радиационно-химический синтез перфторированной полимерной мембраны с сульфокислотными группами

В результаті радіаційно-індукованої прищепної сополімеризації з водних розчинів двох мономерів — акрилової кислоти і натрієвої солі стиролсульфонату — на полімерну плівку з фторованого пропілену-етилену синтезована протонобмінна мембрана з сульфокислотними групами. Розглянуті основні експериментальні параметри, що впливають на процес прищепної сополімеризації.Sulfonic acid proton exchange membranes based on a poly(tetrafluoroethylene-co-hexafluoropropylene) film are synthesized through the graft copolymerization of sodium styrenesulfonate and acrylic acid monomers from binary monomer aqueous solutions. The effects of the main polymerization parameters on the degree of grafting are studied

Brain network modules of meaningful and meaningless objects

Network modularity is a key feature for efficient information processing in the human brain. This information processing is however dynamic and networks can reconfigure at very short time period, few hundreds of millisecond. This requires neuroimaging techniques with sufficient time resolution. Here we use the dense electroencephalography, EEG, source connectivity methods to identify cortical networks with excellent time resolution, in the order of millisecond. We identify functional networks during picture naming task. Two categories of visual stimuli were presented, meaningful (tools, animals) and meaningless (scrambled) objects. In this paper, we report the reconfiguration of brain network modularity for meaningful and meaningless objects. Results showed mainly that networks of meaningful objects were more modular than those of meaningless objects. Networks of the ventral visual pathway were activated in both cases. However a strong occipitotemporal functional connectivity appeared for meaningful object but not for meaningless object. We believe that this approach will give new insights into the dynamic behavior of the brain networks during fast information processing.Comment: The 3rd Middle East Conference on Biomedical Engineering (MECBME'16

Rate distortion optimized graph partitioning for omnidirectional image coding

International audienceOmnidirectional images are spherical signals captured by cameras with 360-degree field of view. In order to be compressed using existing encoders, these signals are mapped to planar domain. A commonly used planar representation is the equirectangular one, which corresponds to a non uniform sampling pattern on the spherical surface. This particularity is not explored in traditional image compression schemes, which treat the input signal as a classical perspective image. In this work, we build a graph-based coder adapted to the spherical surface. We build a graph directly on the sphere. Then, to have computationally feasible graph transforms, we propose a rate-distortion optimized graph partitioning algorithm to achieve an effective trade-off between the distortion of the reconstructed signals, the smoothness of the signal on each subgraph, and the cost of coding the graph partitioning description. Experimental results demonstrate that our method outperforms JPEG coding of planar equirectangular images

Molecular basis for functional switching of GFP by two disparate non-native post-translational modifications of a phenyl azide reaction handle

Through the genetic incorporation of a single phenyl azide group into superfolder GFP (sfGFP) at residue 148 we provide a molecular description of how this highly versatile chemical handle can be used to positively switch protein function in vitro and in vivo via either photochemistry or bioconjugation. Replacement of H148 with p-azido-L-phenylalanine (azF) blue shifts the major excitation peak ∼90 nm by disrupting the H-bond and proton transfer network that defines the chromophore charged state. Bioorthogonal click modification with a simple dibenzylcyclooctyne or UV irradiation shifts the neutral-anionic chromophore equilibrium, switching fluorescence to the optimal ∼490 nm excitation. Click modification also improved quantum yield over both the unmodified and original protein. Crystal structures of both the click modified and photochemically converted forms show that functional switching is due to local conformational changes that optimise the interaction networks surrounding the chromophore. Crystal structure and mass spectrometry studies of the irradiated protein suggest that the phenyl azide converts to a dehydroazepine and/or an azepinone. Thus, protein embedded phenyl azides can be used beyond simple photocrosslinkers and passive conjugation handles, and mimic many natural post-translational modifications: modulation though changes in interaction networks

Tracking precursor lesions of anal squamous cell carcinoma in individuals with HIV

INTRODUÇÃO: O carcinoma espino-celular do canal anal é doença que atinge os adultos de meia idade e corresponde a 4% dos cânceres do trato gastrointestinal baixo. Na população geral a incidência é de 1 em 100.000 habitantes, e entre os homens que fazem sexo com homens essa incidência atinge 35 por 100.000 habitantes, sendo que os portadores de HIV têm esse risco duplicado (70 por 100.000 habitantes). MÉTODO: Foi realizada revisão da literatura com consulta nos periódicos das bases Medline/Pubmed, Scielo e Lilacs cruzando os descritores Rastreamento, Lesões pré-cancerosas, Neoplasias do ânus e HIV. Além da revisão bibliográfica, foi adicionada a este trabalho a experiência pessoal dos autores, e a obtida no Departamento de Gastroenterologia - Divisão Cirúrgica, no ICESP - Instituto do Câncer do Estado de São Paulo Octávio Frias de Oliveira, no Departamento de Moléstias Infeciosas - Casa da AIDS e no Serviço de Coloproctologia do Hospital das Clínicas da Universidade de São Paulo, SP, Brasil. CONCLUSÕES: HIV+ é um grande fator de risco no desenvolvimento de carcinoma espino-celular anal em indivíduos infectados por HPV. A avaliação desses pacientes não deve se restringir à erradicação de condilomas, mas principalmente incluir o rastreamento de lesões displásicas subclínicas potencialmente neoplásicas. Apesar dos métodos de rastreamento ainda não serem ideais, o grande benefício do rastreamento baseia-se no fato de oferecer acompanhamento rigoroso, tornando possível à prevenção ou detecção cada vez mais precoce do carcinoma espino-celular anal.INTRODUCTION: Squamous cell carcinoma of the anal canal is a disease that affects the middle-aged adults and accounts for 4% of cancers of the gastrointestinal tract below. In the general population the incidence is 1 in 100,000, and among men who have sex with men the incidence is 35 per 100,000 inhabitants, those with HIV have doubled this risk (70 per 100,000 inhabitants). METHODS: Was performed literature review in consultation with periodic Medline / Pubmed, Lilacs and Scielo crossing Trackingm, Precancerous conditions, Anus neoplasms and HIV descriptors. Besides the review,was added to this work the authors'personal experiences, and obtained at the Department of Gastroenterology - Surgical Division, in ICESP - Cancer Institute of the State of São Paulo Octavio Frias de Oliveira, in Department of Diseases Infectious - House of AIDS and in the Department of Coloproctology, Hospital das Clinicas, University of São Paulo, Brazil. CONCLUSIONS: HIV + is a major risk factor in developing squamous cell carcinoma anal in individuals infected with HPV. The evaluation of these patients should not restrict itself to the eradication of warts, but mainly include the screening of subclinical dysplastic lesions potentially neoplastic. Despite the screening methods are still not ideal, the great benefit of screening is based on the fact offer closely monitored, making possible the prevention or detection of increasingly early anal squamous cell carcinoma

Human adenovirus type 26 uses sialic acid - bearing glycans as a primary cell entry receptor

Adenoviruses are clinically important agents. They cause respiratory distress, gastroenteritis, and epidemic keratoconjunctivitis. As non-enveloped, double-stranded DNA viruses, they are easily manipulated, making them popular vectors for therapeutic applications, including vaccines. Species D adenovirus type 26 (HAdV-D26) is both a cause of EKC and other diseases and a promising vaccine vector. HAdV-D26–derived vaccines are under investigation as protective platforms against HIV, Zika, and respiratory syncytial virus infections and are in phase 3 clinical trials for Ebola. We recently demonstrated that HAdV-D26 does not use CD46 or Desmoglein-2 as entry receptors, while the putative interaction with coxsackie and adenovirus receptor is low affinity and unlikely to represent the primary cell receptor. Here, we establish sialic acid as a primary entry receptor used by HAdV-D26. We demonstrate that removal of cell surface sialic acid inhibits HAdV-D26 infection, and provide a high-resolution crystal structure of HAdV-D26 fiber-knob in complex with sialic acid

Structural definition of HLA class II-presented SARS-CoV-2 epitopes reveals a mechanism to escape pre-existing CD4+ T cell immunity

CD4+ T cells recognize a broad range of peptide epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which contribute to immune memory and limit COVID-19 disease. We demonstrate that the immunogenicity of SARS-CoV-2 peptides, in the context of the model allotype HLA-DR1, does not correlate with their binding affinity to the HLA heterodimer. Analyzing six epitopes, some with very low binding affinity, we solve X-ray crystallographic structures of each bound to HLA-DR1. Further structural definitions reveal the precise molecular impact of viral variant mutations on epitope presentation. Omicron escaped ancestral SARS-CoV-2 immunity to two epitopes through two distinct mechanisms: (1) mutations to TCR-facing epitope positions and (2) a mechanism whereby a single amino acid substitution caused a register shift within the HLA binding groove, completely altering the peptide-HLA structure. This HLA-II-specific paradigm of immune escape highlights how CD4+ T cell memory is finely poised at the level of peptide-HLA-II presentation

In silico and structural analyses demonstrate that intrinsic protein motions guide T cell receptor complementarity determining region loop flexibility

T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions

Genetically encoded phenyl azide photochemistry drives positive and negative functional modulation of a red fluorescent protein

The photochemical properties of phenyl azide have been exploited to modulate the function of a red autofluorescent protein, mCherry. Using genetic code reprogramming, phenyl azide chemistry has been introduced at functionally strategic positions in mCherry leading to deactivation, activation or enhancement upon UV irradiatio