Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
1.
Nano Lett ; 21(13): 5842-5849, 2021 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-34153185

RESUMO

Hybrids of graphene and metal plasmonic nanostructures are promising building blocks for applications in optoelectronics, surface-enhanced scattering, biosensing, and quantum information. An understanding of the coupling mechanism in these hybrid systems is of vital importance to its applications. Previous efforts in this field mainly focused on spectroscopic studies of strong coupling within the hybrids with no spatial resolution. Here we report direct imaging of the local plasmonic coupling between single Au nanocapsules and graphene step edges at the nanometer scale by photon-induced near-field electron microscopy in an ultrafast electron microscope for the first time. The proximity of a step in the graphene to the nanocapsule causes asymmetric surface charge density at the ends of the nanocapsules. Computational electromagnetic simulations confirm the experimental observations. The results reported here indicate that this hybrid system could be used to manipulate the localized electromagnetic field on the nanoscale, enabling promising future plasmonic devices.


Assuntos
Grafite , Nanoestruturas , Microscopia de Força Atômica , Microscopia Eletrônica , Nanotecnologia
2.
Int J Mol Sci ; 22(14)2021 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34299098

RESUMO

BACKGROUND: This study was designed to investigate the effect of cluster differentiation (CD)39 and CD73 inhibitors on the expresion of tumour-associated macrophages (TAMs), M1- versus M2-tumour phenotypes in mice with colon cancer. METHODS: An in vivo study of co-culture with colon cancer cells and immune cells from the bone marrow (BM) of mice was performed. After the confirmation of the effect of polyoxotungstate (POM-1) as an inhibitor of CD39 on TAMs, the mice were randomly divided into a control group without POM-1 and a study group with POM-1, respectively, after subcutaneous injection of CT26 cells. On day 14 after the injection, the mice were sacrificed, and TAMs were evaluated using fluorescence-activated cell sorting. RESULTS: In the in vivo study, the co-culture with POM-1 significantly increased the apoptosis of CT26 cells. The cell population from the co-culture with POM-1 showed significant increases in the expression of CD11b+ for myeloid cells, lymphocyte antigen 6 complex, locus C (Ly6C+) for monocytes, M1-tumour phenotypes from TAMs, and F4/80+ for macrophages. In the in vivo study, tumour growth in the study group with POM-1 was significantly limited, compared with the control group without POM-1. The expressions of Ly6C+ and major histocompatibility complex class II+ for M1-tumour phenotypes from TAMs on F4/80+ from the tumour tissue in the study group had significantly higher values compared with the control group. CONCLUSION: The inhibition of CD39 with POM-1 prevented the growth of colon cancer in mice, and it was associated with the increased expression of M1-tumour phenotypes from TAMs in the cancer tissue.


Assuntos
Apirase/antagonistas & inibidores , Neoplasias do Colo/prevenção & controle , Polímeros/farmacologia , Macrófagos Associados a Tumor/efeitos dos fármacos , Compostos de Tungstênio/farmacologia , Animais , Antígenos CD , Apoptose , Proliferação de Células , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Prognóstico , Células Tumorais Cultivadas , Macrófagos Associados a Tumor/metabolismo , Macrófagos Associados a Tumor/patologia , Ensaios Antitumorais Modelo de Xenoenxerto
3.
Nature ; 499(7457): 178-83, 2013 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-23823726

RESUMO

We have taken the first steps towards a complete reconstruction of the Mycobacterium tuberculosis regulatory network based on ChIP-Seq and combined this reconstruction with system-wide profiling of messenger RNAs, proteins, metabolites and lipids during hypoxia and re-aeration. Adaptations to hypoxia are thought to have a prominent role in M. tuberculosis pathogenesis. Using ChIP-Seq combined with expression data from the induction of the same factors, we have reconstructed a draft regulatory network based on 50 transcription factors. This network model revealed a direct interconnection between the hypoxic response, lipid catabolism, lipid anabolism and the production of cell wall lipids. As a validation of this model, in response to oxygen availability we observe substantial alterations in lipid content and changes in gene expression and metabolites in corresponding metabolic pathways. The regulatory network reveals transcription factors underlying these changes, allows us to computationally predict expression changes, and indicates that Rv0081 is a regulatory hub.


Assuntos
Redes Reguladoras de Genes , Hipóxia/genética , Redes e Vias Metabólicas/genética , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Adaptação Fisiológica , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Imunoprecipitação da Cromatina , Perfilação da Expressão Gênica , Redes Reguladoras de Genes/genética , Genômica , Hipóxia/metabolismo , Metabolismo dos Lipídeos/genética , Modelos Biológicos , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/fisiologia , Oxigênio/farmacologia , Proteólise , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reprodutibilidade dos Testes , Análise de Sequência de DNA , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Tuberculose/metabolismo , Tuberculose/microbiologia
4.
Proc Natl Acad Sci U S A ; 110(27): 10976-81, 2013 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-23784773

RESUMO

Amyloid is an important class of proteinaceous material because of its close association with protein misfolding disorders such as Alzheimer's disease and type II diabetes. Although the degree of stiffness of amyloid is critical to the understanding of its pathological and biological functions, current estimates of the rigidity of these ß-sheet-rich protein aggregates range from soft (10(8) Pa) to hard (10(10) Pa) depending on the method used. Here, we use time-resolved 4D EM to directly and noninvasively measure the oscillatory dynamics of freestanding, self-supporting amyloid beams and their rigidity. The dynamics of a single structure, not an ensemble, were visualized in space and time by imaging in the microscope an amyloid-dye cocrystal that, upon excitation, converts light into mechanical work. From the oscillatory motion, together with tomographic reconstructions of three studied amyloid beams, we determined the Young modulus of these highly ordered, hydrogen-bonded ß-sheet structures. We find that amyloid materials are very stiff (10(9) Pa). The potential biological relevance of the deposition of such a highly rigid biomaterial in vivo are discussed.


Assuntos
Amiloide/química , Amiloide/ultraestrutura , Amiloide/fisiologia , Fenômenos Biomecânicos , Módulo de Elasticidade , Tomografia com Microscopia Eletrônica , Humanos , Imageamento Tridimensional , Modelos Moleculares , Estrutura Secundária de Proteína
5.
Proc Natl Acad Sci U S A ; 110(23): 9277-82, 2013 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-23690572

RESUMO

Enhanced image contrast has been seen at graphene-layered steps a few nanometers in height by means of photon-induced near-field electron microscopy (PINEM) using synchronous femtosecond pulses of light and electrons. The observed steps are formed by the edges of graphene strips lying on the surface of a graphene substrate, where the strips are hundreds of nanometers in width and many micrometers in length. PINEM measurements reflect the interaction of imaging electrons and induced (near) electric fields at the steps, and this leads to a much higher contrast than that achieved in bright-field transmission electron microscopy imaging of the same strips. Theory and numerical simulations support the experimental PINEM findings and elucidate the nature of the electric field at the steps formed by the graphene layers. These results extend the range of applications of the experimental PINEM methodology, which has previously been demonstrated for spherical, cylindrical, and triangular nanostructures, to shapes of high aspect ratio (rectangular strips), as well as into the regime of atomic layer thicknesses.


Assuntos
Elétrons , Grafite/química , Microscopia Eletrônica/métodos , Nanoestruturas/ultraestrutura , Fótons , Nanoestruturas/química
6.
BMC Genomics ; 13: 120, 2012 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-22452820

RESUMO

BACKGROUND: The sequence of the pathogen Mycobacterium tuberculosis (Mtb) strain H37Rv has been available for over a decade, but the biology of the pathogen remains poorly understood. Genome sequences from other Mtb strains and closely related bacteria present an opportunity to apply the power of comparative genomics to understand the evolution of Mtb pathogenesis. We conducted a comparative analysis using 31 genomes from the Tuberculosis Database (TBDB.org), including 8 strains of Mtb and M. bovis, 11 additional Mycobacteria, 4 Corynebacteria, 2 Streptomyces, Rhodococcus jostii RHA1, Nocardia farcinia, Acidothermus cellulolyticus, Rhodobacter sphaeroides, Propionibacterium acnes, and Bifidobacterium longum. RESULTS: Our results highlight the functional importance of lipid metabolism and its regulation, and reveal variation between the evolutionary profiles of genes implicated in saturated and unsaturated fatty acid metabolism. It also suggests that DNA repair and molybdopterin cofactors are important in pathogenic Mycobacteria. By analyzing sequence conservation and gene expression data, we identify nearly 400 conserved noncoding regions. These include 37 predicted promoter regulatory motifs, of which 14 correspond to previously validated motifs, as well as 50 potential noncoding RNAs, of which we experimentally confirm the expression of four. CONCLUSIONS: Our analysis of protein evolution highlights gene families that are associated with the adaptation of environmental Mycobacteria to obligate pathogenesis. These families include fatty acid metabolism, DNA repair, and molybdopterin biosynthesis. Our analysis reinforces recent findings suggesting that small noncoding RNAs are more common in Mycobacteria than previously expected. Our data provide a foundation for understanding the genome and biology of Mtb in a comparative context, and are available online and through TBDB.org.


Assuntos
Actinobacteria/genética , Evolução Molecular , Mycobacterium tuberculosis/genética , Mycobacterium/genética , Actinobacteria/classificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Coenzimas/genética , Coenzimas/metabolismo , Reparo do DNA , Bases de Dados Genéticas , Ácidos Graxos/genética , Ácidos Graxos/metabolismo , Genoma Bacteriano , Genômica , Metabolismo dos Lipídeos/genética , Metaloproteínas/genética , Metaloproteínas/metabolismo , Cofatores de Molibdênio , Mycobacterium/classificação , Mycobacterium tuberculosis/classificação , Filogenia , Pteridinas/metabolismo , RNA não Traduzido/química , RNA não Traduzido/metabolismo
7.
J Am Chem Soc ; 134(22): 9146-9, 2012 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-22591381

RESUMO

We report the anisotropic atomic expansion dynamics of multi-walled carbon nanotubes, using 4D electron microscopy. From time-resolved diffraction on the picosecond to millisecond scale, following ultrafast heating at the rate of 10(13) K/s, it is shown that nanotubes expand only in the radial (intertubule) direction, whereas no significant change is observed in the intratubular axial or equatorial dimensions. The non-equilibrium heating occurs on an ultrafast time scale, indicating that the anisotropy is the result of an efficient electron-lattice coupling and is maintained up to equilibration. The recovery time, which measures the heat dissipation rate for equilibration, was found to be on the order of ∼100 µs. This recovery is reproduced theoretically by considering the composite specimen-substrate heat exchange.

8.
J Phys Chem A ; 116(46): 11128-33, 2012 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-22741915

RESUMO

Electrons and photons, when interacting via a nanostructure, produce a new way of imaging in space and time, termed photon-induced near field electron microscopy or PINEM [Barwick et al. Nature 2009, 462, 902]. The phenomenon was described by considering the evanescent field produced by the nanostructure, but quantification of the experimental results was achieved by solving the Schrödinger equation for the interaction of the three bodies. The question remained, is the nonrelativistic formulation sufficient for this description? Here, relativistic and nonrelativistic quantum mechanical formulations are compared for electron-photon interaction mediated by nanostructures, and it is shown that there is an exact equivalence for the two formulations. The nonrelativistic formulation was found to be valid in the relativistic regime when using in the former formulation the relativistically corrected velocity (and the corresponding values of momentum and energy). In the PINEM experiment, 200 keV electrons were utilized, giving the experimental (relativistically corrected) velocity to be 0.7c(v without relativistic correction is 0.885c). When this value (0.7c), together with those of the corresponding momentum (p(c) = mv) and energy (E(c) = (1/2)mv(2)), is used in the first order solution of the Schrödinger formulation, an exact equivalence is obtained.


Assuntos
Fótons , Microscopia Eletrônica , Nanoestruturas/química , Teoria Quântica
9.
Medicine (Baltimore) ; 101(46): e31734, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36401433

RESUMO

RATIONALE: Myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD) is one of auto-immune demyelinating diseases of nervous system. Although both regional anesthesia and general anesthesia has been successfully performed in the patient with demyelinating diseases of nervous system, it has been controversial which one is better. PATIENT CONCERNS: Forty-four male patient was admitted for arthroscopic elbow surgery due to limitation of range of motion. The patient was diagnosed as MOGAD with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, and steroid was used to prevent and treat symptoms and signs. DIAGNOSIS: He was diagnosed as MOGAD with anti-NMDA receptor encephalitis, 1 year ago. The patient complaint of dizziness, diplopia, nausea, vomiting, seizure, general weakness and so on when he was confirmed as MOGAD with anti-NMDA receptor encephalitis. The diagnosis of MOGAD was confirmed with positive anti-myelin oligodendrocyte glycoprotein (MOG) Immunoglobulin (Ig)G and negative anti-aquaporin 4 (AQP4) IgG in the blood. INTERVENTIONS AND OUTCOMES: After steroid cover, total intravenous anesthesia (TIVA) with remimazolam and remifentanil was established for the patients. Rocuronium was administered under monitoring of neuromuscular blockade, using train of 4 (TOF). The operation was performed without any event under right lateral decubitus position. The patient was uneventfully recovered from anesthesia. LESSONS: The case report showed total intravenous anesthesia with remimazolam and remifentanil under proper monitoring was successfully performed in the patient with MOGAD.


Assuntos
Encefalite Antirreceptor de N-Metil-D-Aspartato , Doenças Desmielinizantes , Masculino , Humanos , Encefalite Antirreceptor de N-Metil-D-Aspartato/diagnóstico , Encefalite Antirreceptor de N-Metil-D-Aspartato/tratamento farmacológico , Remifentanil , Autoanticorpos , Glicoproteína Mielina-Oligodendrócito , Anestesia Geral , Oligodendroglia
10.
J Am Chem Soc ; 133(6): 1730-3, 2011 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-21254771

RESUMO

We report direct visualization of irreversible chemical reactions in space and time with 4D electron microscopy. Specifically, transient structures are imaged following electron transfer in copper-tetracyanoquinodimethane [Cu(TCNQ)] crystals, and the oxidation/reduction process, which is irreversible, is elucidated using the single-shot operation mode of the microscope. We observed the fast, initial structural rearrangement due to Cu(+) reduction and the slower growth of metallic Cu(0) nanocrystals (Ostwald ripening) following initiation of the reaction with a pulse of visible light. The mechanism involves electron transfer from TCNQ anion-radical to Cu(+), morphological changes, and thermally driven growth of discrete Cu(0) nanocrystals embedded in an amorphous carbon skeleton of TCNQ. This in situ visualization of structures during reactions should be extendable to other classes of reactive systems.


Assuntos
Microscopia Eletrônica/métodos , Transporte de Elétrons , Nanopartículas/química , Fenômenos Ópticos , Fatores de Tempo
11.
Proc Natl Acad Sci U S A ; 105(35): 13105-10, 2008 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-18728196

RESUMO

SigH is a key regulator of an extensive transcriptional network that responds to oxidative, nitrosative, and heat stresses in Mycobacterium tuberculosis, and this sigma factor is required for virulence in animal models of infection. SigH is negatively regulated by RshA, its cognate anti-sigma factor, which functions as a stress sensor and redox switch. While RshA provides a direct mechanism for sensing stress and activating transcription, bacteria use several types of signal transduction systems to sense the external environment. M. tuberculosis encodes several serine-threonine protein kinase signaling molecules, 2 of which, PknA and PknB, are essential and have been shown to regulate cell morphology and cell wall synthesis. In this work, we demonstrate that SigH and RshA are phosphorylated in vitro and in vivo by PknB. We show that phosphorylation of RshA, but not SigH, interferes with the interaction of these 2 proteins in vitro. Consistent with this finding, negative regulation of SigH activity by RshA in vivo is partially relieved in strains in which pknB is over-expressed, resulting in increased resistance to oxidative stress. These findings demonstrate an interaction between the signaling pathways mediated by PknB and the stress response regulon controlled by SigH. The intersection of these apparently discrete regulatory systems provides a mechanism by which limited activation of the SigH-dependent stress response in M. tuberculosis can be achieved. Coordination of the PknB and SigH regulatory pathways through phosphorylation of RshA may lead to adaptive responses that are important in the pathogenesis of M. tuberculosis infection.


Assuntos
Proteínas de Bactérias/metabolismo , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/genética , Proteínas Serina-Treonina Quinases/metabolismo , Regulon/genética , Fator sigma/metabolismo , Dissulfetos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Mycobacterium tuberculosis/citologia , Mycobacterium tuberculosis/efeitos dos fármacos , Monoéster Fosfórico Hidrolases/farmacologia , Fosforilação/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos
12.
Nano Lett ; 10(11): 4767-73, 2010 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-20964287

RESUMO

In this letter, we report a novel method of visualizing nanoscale friction in space and time using ultrafast electron microscopy (UEM). The methodology is demonstrated for a nanoscale movement of a single crystal beam on a thin amorphous membrane of silicon nitride. The movement results from the elongation of the crystal beam, which is initiated by a laser (clocking) pulse, and we examined two types of beams: those that are free of friction and the others which are fixed on the substrate. From observations of image change with time we are able to decipher the nature of microscopic friction at the solid-solid interface: smooth-sliding and periodic slip-stick friction. At the molecular and nanoscale level, and when a force parallel to the surface (expansion of the beam) is applied, the force of gravity as a (perpendicular) load cannot explain the observed friction. An additional effective load being 6 orders of magnitude larger than that due to gravity is attributed to Coulombic/van der Waals adhesion at the interface. For the case under study, metal-organic crystals, the gravitational force is on the order of piconewtons whereas the static friction force is 0.5 µN and dynamic friction is 0.4 µN; typical beam expansions are 50 nm/nJ for the free beam and 10 nm/nJ for the fixed beam. The method reported here should have applications for other materials, and for elucidating the origin of periodic and chaotic friction and their relevance to the efficacy of nano(micro)-scale devices.


Assuntos
Fricção , Imageamento Tridimensional/métodos , Microscopia Eletrônica/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Teste de Materiais/métodos , Tamanho da Partícula
13.
J Am Chem Soc ; 131(8): 2806-8, 2009 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-19055399

RESUMO

We report the structure of isolated biomolecules, uracil and guanine, demonstrating the capability of a newly developed electron diffraction apparatus augmented with surface-assisted IR laser desorption. This UED-4 apparatus provides a pulsed, dense molecular beam, which is stable for many hours and possibly days. From the diffraction patterns, it is evident that the plume composition is chemically pure, without detectable background from ions, fragmentation products, or molecular aggregates. The vibrational temperature deduced is indeed lower than the translational temperature of the plume indicating that the molecules are intact on such short time scales. The structures of uracil and guanine were refined at the deduced internal temperatures, and we compare the results with those predicted by density functional theory. Such experimental capability opens the door for many other studies of the structure (and dynamics) of biomolecules.


Assuntos
Guanina/química , Uracila/química , Elétrons , Raios Infravermelhos , Lasers , Modelos Moleculares , Espalhamento de Radiação
14.
J Biochem Mol Biol ; 40(4): 486-93, 2007 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-17669263

RESUMO

Atopic dermatitis (AD) is a chronic inflammatory skin disease and the pathogenesis of AD is associated with the release of various cytokines/chemokines due to activated Th(2) immune responses. Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG dinucleotide in the context of particular base sequence (CpG motifs) are known to have the immunostimulatory activities in mice and to convert from Th(2) to Th(1) immune responses in AD. We aimed to investigate that CpG ODN, especially phosphodiester form, can stimulate the protective immunity in NC/Nga mice with AD. We isolated BMDCs from NC/Nga mice and then, cultured with GM-CSF and IL-4 for 6 days, and treated for 2 days by either phosphorothioate ODN or phosphodiester ODN. CpG ODN-treated DCs resulted in more production of IL-12. When CpG ODN-treated DCs were intravenously injected into the NC/Nga mice, the NC/Nga mice with CpG ODN-treated DCs showed significant improvement of AD symptoms and decrease of IgE level. Histopathologically, the NC/Nga mice skin with CpG ODN-treated DCs showed the decreased IL-4 and TARC expression comparing with non-injected mice. These results may suggest that phosphodiester CpG ODN-treated DCs might function as a potent adjuvant for AD in a mouse model.


Assuntos
Células Dendríticas/efeitos dos fármacos , Dermatite Atópica/patologia , Oligodesoxirribonucleotídeos/farmacologia , Animais , Células da Medula Óssea/efeitos dos fármacos , Citocinas/biossíntese , Feminino , Antígenos de Histocompatibilidade/metabolismo , Imunoglobulina E/sangue , Camundongos , Camundongos Mutantes , Pele/patologia
15.
Struct Dyn ; 4(4): 044028, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28653019

RESUMO

In this article, we present a continuum mechanics based approach for modeling thermally induced single-nanoparticle phase transitions studied in ultrafast electron microscopy. By using coupled differential equations describing heat transfer and the kinetics of the phase transition, we determine the major factors governing the time scales and efficiencies of thermal switching in individual spin-crossover nanoparticles, such as the thermal properties of the (graphite) substrate, the particle thickness, and the interfacial thermal contact conductance between the substrate and the nanoparticle. By comparing the simulated dynamics with the experimental single-particle diffraction time profiles, we demonstrate that the proposed non-equilibrium phase transition model can fully account for the observed switching dynamics.

16.
Struct Dyn ; 4(5): 054303, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28781982

RESUMO

Efforts to understand matter at ever-increasing spatial and temporal resolutions have led to the development of instruments such as the ultrafast transmission electron microscope (UEM) that can capture transient processes with combined nanometer and picosecond resolutions. However, analysis by UEM is often associated with extended acquisition times, mainly due to the limitations of the electron gun. Improvements are hampered by tradeoffs in realizing combinations of the conflicting objectives for source size, emittance, and energy and temporal dispersion. Fundamentally, the performance of the gun is a function of the cathode material, the gun and cathode geometry, and the local fields. Especially shank emission from a truncated tip cathode results in severe broadening effects and therefore such electrons must be filtered by applying a Wehnelt bias. Here we study the influence of the cathode geometry and the Wehnelt bias on the performance of a photoelectron gun in a thermionic configuration. We combine experimental analysis with finite element simulations tracing the paths of individual photoelectrons in the relevant 3D geometry. Specifically, we compare the performance of guard ring cathodes with no shank emission to conventional truncated tip geometries. We find that a guard ring cathode allows operation at minimum Wehnelt bias and improve the temporal resolution under realistic operation conditions in an UEM. At low bias, the Wehnelt exhibits stronger focus for guard ring than truncated tip cathodes. The increase in temporal spread with bias is mainly a result from a decrease in the accelerating field near the cathode surface. Furthermore, simulations reveal that the temporal dispersion is also influenced by the intrinsic angular distribution in the photoemission process and the initial energy spread. However, a smaller emission spot on the cathode is not a dominant driver for enhancing time resolution. Space charge induced temporal broadening shows a close to linear relation with the number of electrons up to at least 10 000 electrons per pulse. The Wehnelt bias will affect the energy distribution by changing the Rayleigh length, and thus the interaction time, at the crossover.

17.
PLoS One ; 12(10): e0186380, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29045436

RESUMO

Current post-exposure prophylaxis for rabies virus infection has several limitations in terms of supply, cost, safety, and efficacy. Attempts to replace human or equine rabies immune globulins (HRIG or ERIG) have been made by several companies and institutes. We developed potent monoclonal antibodies to neutralize a broad spectrum of rabies viruses by screening hybridomas received from the U.S. Centers for Disease Control and Prevention (CDC). Two kinds of chimeric human antibodies (chimeric #7 and #17) were constructed by cloning the variable regions from selected hybridomas and the constant region of a human antibody. Two antibodies were bound to antigenic site III and I/IV, respectively, and were able to neutralize 51 field isolates of rabies virus that were isolated at different times and places such as Asia, Africa, North America, South America, and Australia. These two antibodies neutralize rabies viruses with high efficacy in an in vivo test using Syrian hamster and mouse models and show low risk for adverse immunogenicity.


Assuntos
Anticorpos Monoclonais/administração & dosagem , Anticorpos Neutralizantes/administração & dosagem , Vírus da Raiva/imunologia , Raiva/prevenção & controle , África , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/genética , Anticorpos Neutralizantes/imunologia , Ásia , Austrália , Centers for Disease Control and Prevention, U.S. , Modelos Animais de Doenças , Cavalos/virologia , Humanos , Hibridomas/imunologia , Mesocricetus/virologia , Camundongos , América do Norte , Raiva/imunologia , Raiva/virologia , Vírus da Raiva/patogenicidade , América do Sul , Estados Unidos
18.
Int Neurourol J ; 20(Suppl 2): S76-83, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27915479

RESUMO

This article is a mini-review that provides a general overview for next-generation sequencing (NGS) and introduces one of the most popular NGS applications, whole genome sequencing (WGS), developed from the expansion of human genomics. NGS technology has brought massively high throughput sequencing data to bear on research questions, enabling a new era of genomic research. Development of bioinformatic software for NGS has provided more opportunities for researchers to use various applications in genomic fields. De novo genome assembly and large scale DNA resequencing to understand genomic variations are popular genomic research tools for processing a tremendous amount of data at low cost. Studies on transcriptomes are now available, from previous-hybridization based microarray methods. Epigenetic studies are also available with NGS applications such as whole genome methylation sequencing and chromatin immunoprecipitation followed by sequencing. Human genetics has faced a new paradigm of research and medical genomics by sequencing technologies since the Human Genome Project. The trend of NGS technologies in human genomics has brought a new era of WGS by enabling the building of human genomes databases and providing appropriate human reference genomes, which is a necessary component of personalized medicine and precision medicine.

19.
Health Phys ; 111(3 Suppl 3): S183-S192, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27676598

RESUMO

The simultaneous determination of the depth of an embedded source and its radioactivity in the medium at the environmental surveys is a very useful and advisable method for an in-situ gamma-ray measurement with respect to the time and cost constraint. An algorithm for the determination of the source depth and its radioactivity in the medium was developed using the information on the uncollided photon fluences and measured net count rates, which mean not scattered fluences and background subtracted count rate, at the detector positions. Uncollided photon fluences were calculated at several source depths in the medium as well as at detector positions from the Monte Carlo N-Particle (MCNP) simulation. The results were then used to establish a database to output their values according to the source depth in the medium by inputting the photon energy and detector position from the medium. A simple program about the simultaneous determination of two variables was applied to the results on a task to find out the depth and activity of Cs and Cs at in-situ gamma-ray spectrometry. Less than 10% and 15% differences compared with the real values at the source depth and radioactivity, respectively, were achieved using the developed program.

20.
PLoS One ; 11(3): e0152145, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27003599

RESUMO

Expression of SigH, one of 12 Mycobacterium tuberculosis alternative sigma factors, is induced by heat, oxidative and nitric oxide stresses. SigH activation has been shown to increase expression of several genes, including genes involved in maintaining redox equilibrium and in protein degradation. However, few of these are known to be directly regulated by SigH. The goal of this project is to comprehensively define the Mycobacterium tuberculosis genes and operons that are directly controlled by SigH in order to gain insight into the role of SigH in regulating M. tuberculosis physiology. We used ChIP-Seq to identify in vivo SigH binding sites throughout the M. tuberculosis genome, followed by quantification of SigH-dependent expression of genes linked to these sites and identification of SigH-regulated promoters. We identified 69 SigH binding sites, which are located both in intergenic regions and within annotated coding sequences in the annotated M. tuberculosis genome. 41 binding sites were linked to genes that showed greater expression following heat stress in a SigH-dependent manner. We identified several genes not previously known to be regulated by SigH, including genes involved in DNA repair, cysteine biosynthesis, translation, and genes of unknown function. Experimental and computational analysis of SigH-regulated promoter sequences within these binding sites identified strong consensus -35 and -10 promoter sequences, but with tolerance for non-consensus bases at specific positions. This comprehensive identification and validation of SigH-regulated genes demonstrates an extended SigH regulon that controls an unexpectedly broad range of stress response functions.


Assuntos
Proteínas de Bactérias/genética , Mycobacterium tuberculosis/genética , Regulon/genética , Fator sigma/genética , Estresse Fisiológico/genética , Transcrição Gênica/genética , Sítios de Ligação/genética , Perfilação da Expressão Gênica/métodos , Regulação Bacteriana da Expressão Gênica/genética , Óperon/genética , Regiões Promotoras Genéticas/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA