Reaction mechanisms of flavins and flavoproteins from an electronic-structure perspective / Mecanismos de reação de flavinas e flavoproteínas por uma perspectiva de estrutura eletrônica

Proteins equipped with flavin adenine dinucleotides (FAD) or flavin mononucleotides (FMN) are named flavoproteins and constitute about 1% of all existing proteins. They catalyze redox, acid-base and photochemical reactions in a variety of biochemical phenomena that goes from energy metabolism to DNA repair and light sensing. The versatility observed in flavoproteins is ultimately a balance of flavin intrinsic properties modulated by a protein environment. This thesis aims to investigate how flavoproteins work by systematic evaluating flavin properties and reactivity. In particular, the mechanism of fumarate reduction by the flavoenzyme fumarate reductase Fcc3 was determined. Electronic-structure calculations were used for this task based on rigorous calibration with experimental data and error assessment. Flavin properties at chemical accuracy were obtained with single reference coupled-cluster CCSD(T) calculations at the complete basis set limit. Density functional theory was demonstrated an excellent alternative with lower computational costs and slightly less accuracy. Flavin protonation and tautomerism were shown to be important modulators of flavin properties and reactivity, with the possibility of various tautomers existing at neutral pH. Regarding flavin redox properties, an analysis based on multiconfigurational wave function weights was proposed for categorizing flavin redox reactions as hydride or hydrogen-atom transfers. This analysis is an upgrade over traditional partial charges methods and can be applied not only to flavin reactions but to any protoncoupled electron transfer. In the investigation of the enzymatic mechanism of fumarate reduction, the reaction was determined as a nucleophilic addition by hydride transfer with carbanion formation. Fumarate reductase employs electrostatic catalysis in contrast to previous proposals of substrate straining and general-acid catalysis. Also, hydride transfer was shown to be vibronically adiabatic with low tunneling contribution. These findings give new insights into the mechanisms of fumarate reductases and provide a framework for future computational studies of flavoproteins in general. The analyses and benchmark studies presented can be used to build better models of properties and reactivity of flavins and flavoproteins

Proteínas equipadas com dinucleotídeos de flavina-adenina (FAD) e mononucleotídeos de flavina (FMN) são chamadas flavoproteínas e constituem cerca de 1% de todas as proteínas existentes. Elas catalisam reações redox, ácido-base e fotoquímicas numa variedade de fenômenos bioquímicos que vão desde o metabolismo energético até reparo de DNA e captação de luz. A versatilidade observada em flavoproteínas é em última instância um balanço das propriedades intrínsecas de flavinas moduladas por um ambiente proteico. Esta tese busca investigar como flavoproteínas funcionam através de avaliações sistemáticas de propriedades e reatividade de flavinas. Em particular, o mecanismo de redução de fumarato pela flavoenzima fumarato redutase Fcc3 foi determinado. Cálculos de estrutura eletrônica foram usados para esta tarefa com base em rigorosa calibração com dados experimentais e avaliação de erros. As propriedades de flavinas foram determinadas com acurácia química com cálculos monoconfiguracionais de coupled-cluster CCSD(T) no limite de conjunto base completo. A teoria do funcional da densidade mostrou-se uma alternativa excelente com menor custo computacional e um pouco menos de acurácia. Protonação e tautomerismo de flavinas mostraram-se moduladores importantes de suas propriedades e reatividade, com a possibilidade de vários tautômeros existirem em pH neutro. Em relação às propriedades redox de flavinas, uma análise baseada nos pesos de funções de onda multiconfiguracionais foi proposta para categorizar as reações redox de flavinas como transferências de hidreto ou hidrogênio. Esta análise é uma melhoria em relação aos métodos tradicionais de cargas parciais e pode ser aplicada não apenas para reações de flavinas mas para qualquer transferência de próton acoplada a elétrons. Na investigação do mecanismo enzimático de redução de fumarato, a reação foi designada como uma adição nucleofílica por transferência de hidreto e formação de carbânion. A fumarato redutase usa catálise eletrostática diferentemente de prospostas anteriores envolvendo distorção do substrato e catálise ácida geral. Além disso, a transferência de hidreto mostrou-se vibronicamente adiabática com pouca contribuição de tunelamento. Estas descobertas abrem novas perspectivas sobre os mecanismos de fumarato redutases e fornecem uma base para estudos computacionais futuros sobre flavoproteínas em geral. As análises e estudos comparativos apresentados podem ser usados para construir melhores modelos para propriedades e reatividade de flavinas e flavoproteínas

Investigation of the influence of clathrate hydrate crystals on the structuring of homeopathic high dilutions

High dilutions (HD) of drugs used in homeopathy are mostly too dilute to contain original drug molecules. But evidences support their specific biological and therapeutic effects. The reason behind this is thought to be water structure characteristic of the original drug. Spectroscopic studies indicate that the specific water structure in HDs can be resolved into free water molecules, hydrogen bonding strength of water hydroxyl, number of hydrogen bonds and clathrate hydrate crystals (CHC). HDs are prepared in EtOH water solution by serial dilution and mechanical agitation, and are called potencies. The objective of the present study is to further confirm the presence of CHCs in the two potencies of three drugs. Electronic spectra of the HDs of the potencies indicate two broad peaks and marked difference in intensities of absorption. Furior Transform Infrared (FT-IR) spectra of the test potencies and their control show difference in intensity shift and contour shape of OH stretching and bending bands. All the experimental data indicate the presence of CHCs in varying amounts in the test potencies.

Computational chemistry approaches in studies on industrial enzymes / 生物工程学报

We review major computational chemistry techniques applied in industrial enzyme studies, especially approaches intended for guiding enzyme engineering. These include molecular mechanics force field and molecular dynamics simulation, quantum mechanical and combined quantum mechanical/molecular mechanical approaches, electrostatic continuum models, molecular docking, etc. These approaches are essentially introduced from the following two angles for viewing: one is about the methods themselves, including the basic concepts, the primary computational results, and potential advantages and limitations; the other is about obtaining valuable information from the respective calculations to guide the design of mutants and mutant libraries.

Variations in ß(T)-function due to addition of LiI-4AgI system / Variaciones en la función ß(T) - por la adición del sistema LiI-4AgI / Variações na função ß(T) devido a adição do sistema Lil-4Agl

Abstract Impedance spectroscopy measurements of the LiI-4AgI samples, in the frequency range 20 Hz-1 MHz, and in the temperature range between 353 K and 378 K were made. Both pure and lithium-doped silver iodide showed blocking phenomena in the electrodes and the grain boundary. The blocking phenomena allowed a change in the transport properties of the pure compound in respect to the doped compound as the temperature varied. The curves of electrical modulus in the LiI-4AgI system show asymmetric peaks corresponding with a weak correlation between mobile ions in the diffusion process. The electrical conductivity in the Agl-Lil system can be described using a stretched relaxation function of the Kohlrausch-Williams-Watts (KWW) type. We speculat e that the phase of lithium dissolved in the silver iodide favors the formation of islands that disperses the conductivity due to the modification of the relationship among the microscopic energies: microscopic energy and migration energy.

Resumen Se tomaron medidas de espectroscopia de impedancia de muestras de Lil-4Agl en el rango de frecuencia de 20 Hz-1 MHz y en el rango de temperatura entre 353 K y 378 K. Tanto el litio puro como el litio dopado con ioduro de plata mostraron fenómenos de bloqueo en los electrodos y la frontera de grano. Los fenómenos de bloqueo permitieron un cambio en las propiedades de transporte del compuesto puro respecto del compuesto dopado a medida que variaba la temperatura. Las curvas del módulo eléctrico en el sistema LiI-4AgI muestran picos asimétricos correspondientes a una débil correlación entre iones móviles en el proceso de difusión. La conductividad eléctrica en el sistema Agl-Lil se puede describir usando una normalización de la función de relajación del tipo Kohlrausch-Williams-Watts (KWW). Especulamos que la fase de litio disuelto en ioduro de plata favorece la formación de islas que dispersan la conductividad debido a la modificación de la relación entre las energías microscopias: energía microscópica y energía de migración.

Resumo Foram realizadas medidas de espectroscopia de impedancia de amostras de Lil-4Agl na faixa de frequência de 20 Hz - 1 MHz e na faixa de temperatura entre 353 e 378 K. Tanto o litio puro como o litio contaminado com iodeto de prata mostram fenômenos de bloqueio nos eletrodos e nos limites do grão. Os fenômenos de bloqueio permitiram uma mudança nas propriedades de transporte do composto puro em respeito ao composto contaminado, à medida que se variava a temperatura. As curvas do módulo elétrico no sistema Lil-4Agl mostraram picos assimétricos correspondentes a uma correlação débil entre ions móveis no processo de difusão. A condutividade elétrica no sistema AgI-Lil pode ser descrita utilizando uma normalização da função de relaxação do tipo Kohlrausch- Williams-Watts (KWW). Especulamos que a fase de litio dissolvida em iodeto de prata favorece a formação de ilhas que dispersam a condutividade devido a modificação da relação entre as energias microscópicas: energia microscópica e energia de migração.

Multilayer Coating of Tetrandrine-loaded PLGA nanoparticles: Effect of surface charges on cellular uptake rate and drug release profile / 华中科技大学学报（医学）（英德文版）

The effect of surface charges on the cellular uptake rate and drug release profile of tetrandrine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TPNs) was studied. Stabilizer-free nanoprecipitation method was used in this study for the synthesis of TPNs. A typical layer-by-layer approach was applied for multi-coating particles' surface with use of poly(styrene sulfonate) sodium salt (PSS) as anionic layer and poly(allylamine hydrochloride) (PAH) as cationic layer. The modified TPNs were characterized by different physicochemical techniques such as Zeta sizer, scanning electron microscopy and transmission electron microscopy. The drug loading efficiency, release profile and cellular uptake rate were evaluated by high performance liquid chromatography and confocal laser scanning microscopy, respectively. The resultant PSS/PAH/PSS/PAH/TPNs (4 layers) exhibited spherical-shaped morphology with the average size of 160.3±5.165 nm and zeta potential of-57.8 mV. The encapsulation efficiency and drug loading efficiency were 57.88% and 1.73%, respectively. Multi-layer coating of polymeric materials with different charges on particles' surface could dramatically influence the drug release profile of TPNs (4 layers vs. 3 layers). In addition, variable layers of surface coating could also greatly affect the cellular uptake rate of TPNs in A549 cells within 8 h. Overall, by coating particles' surface with those different charged polymers, precise control of drug release as well as cellular uptake rate can be achieved simultaneously. Thus, this approach provides a new strategy for controllable drug delivery.

In silico investigation of agonist activity of a structurally diverse set of drugs to hPXR using HM-BSM and HM-PNN / 华中科技大学学报（医学）（英德文版）

The human pregnane X receptor (hPXR) plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards hPXR. Heuristic method (HM)-Best Subset Modeling (BSM) and HM-Polynomial Neural Networks (PNN) were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain (AD) of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved (for HM-BSM, r (2)=0.881, q LOO (2) =0.797, q EXT (2) =0.674; for HM-PNN, r (2)=0.882, q LOO (2) =0.856, q EXT (2) =0.655). The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to hPXR.

Spray deposition on coffee leaves from airblast sprayers with and without electrostatic charge / Depósito de calda aplicada em folhas de cafeeiro promovida pela pulverização hidropneumática com e sem carga eletrostática

Studies on the quality of applications of plant protection products on coffee crops are lacking. Thus, we studied spray deposition on coffee leaves and losses to the soil from hydropneumatic spraying at different spray volumes and with and without an electrostatic charge. The experiment was set up using randomized blocks in a factorial design (4 x 2 + 1). Spray deposition on the upper, middle and lower parts of the canopy and losses to the soil were evaluated using Brilliant Blue tracer. Applications were made at 200, 300, 400 and 500 L ha-1 with a conventional airblast sprayer (axial fan type) and an airblast sprayer with directed air jets. Applications were also made with an electrostatic sprayer at 130 L ha-1. Electrostatic spraying resulted in greater spray deposition on the lower part of the coffee canopy compared to non-electrostatic spraying. On the lower and middle parts of the plants, the sprayer equipped with directed air ducts performed better than the sprayer with nozzles arranged along the lateral arcs (axial). The spray volume of the airblast sprayers without electrostatic charge (200 to 500 L ha-1) did not influence spray deposition on the plant leaves and losses to the soil, which were lower with the electrostatic sprayer.

Estudos relacionados à qualidade da aplicação de produtos fitossanitários no cafeeiro são ainda escassos. Dessa forma, o objetivo deste trabalho foi estudar a deposição de calda pulverizada em folhas de cafeeiro e a perda para o solo promovidas pela pulverização hidropneumática, em diferentes volumes de calda, com e sem carga eletrostática. O experimento foi conduzido em delineamento em blocos casualizados, em esquema fatorial 2 x 4 + 1. Foram avaliadas a deposição de calda nos terços superior, médio e inferior e as perdas para o solo promovidas pela pulverização do traçador Azul Brilhante, empregando um pulverizador hidropneumático convencional e um com dutos de ar direcionado, com volumes de calda de 200, 300, 400 e 500 L ha-1, e um pulverizador eletrostático, com volume de calda de 130 L ha-1. A pulverização eletrostática proporcionou maior deposição de calda no terço inferior do cafeeiro em comparação à pulverização não eletrostática. Nesta região e na parte média das plantas, o pulverizador dotado de dutos de ar direcionado teve melhor desempenho do que o equipamento com bicos dispostos ao longo dos arcos laterais (Axial). O volume de calda empregado nos pulverizadores hidropneumáticos sem carga eletrostática (200 a 500 L ha-1) não influenciou a deposição de calda nas plantas e as perdas para o solo, que foram menores quando se empregou o pulverizador eletrostático.

Troubleshooting of Electro-Static Discharge Test for Medical Injection Pump / 中国医疗器械杂志

This article presents several common problems.of medical injection pump through one case of ESD troubleshooting. Expounds the causes of the problem and provides solutions.

Molecular mechanism of SCARB2-mediated attachment and uncoating of EV71

Unlike the well-established picture for the entry of enveloped viruses, the mechanism of cellular entry of non-enveloped eukaryotic viruses remains largely mysterious. Picornaviruses are representative models for such viruses, and initiate this entry process by their functional receptors. Here we present the structural and functional studies of SCARB2, a functional receptor of the important human enterovirus 71 (EV71). SCARB2 is responsible for attachment as well as uncoating of EV71. Differences in the structures of SCARB2 under neutral and acidic conditions reveal that SCARB2 undergoes a pivotal pH-dependent conformational change which opens a lipid-transfer tunnel to mediate the expulsion of a hydrophobic pocket factor from the virion, a pre-requisite for uncoating. We have also identified the key residues essential for attachment to SCARB2, identifying the canyon region of EV71 as mediating the receptor interaction. Together these results provide a clear understanding of cellular attachment and initiation of uncoating for enteroviruses.

Lipoatrofia semicircular, una visión general a una patología laboral emergente en Chile / Semicircular lipatrophy, an overview of emerging labor pathology in Chile

La Lipoatrofia Semicircular (LS) es una enfermedad idiopática, que se caracteriza por una atrofia reversible y localizada, ya sea total o parcial, del tejido adiposo subcutáneo y que se ubica en zonas de contacto de la piel de las extremidades con el inmobiliario. Se caracteriza por presentarse en brotes endémicos, cuyo único factor en común es el lugar de trabajo. Sus causas son desconocidas, pero en la actualidad se proponen factores asociados como: el contacto de la zona afectada con inmobiliario, presencia de radiación electromagnética, presencia de descargas electroestáticas y humedad ambiental relativa baja. Un modelo actual para explicar la patogenia de esta enfermedad involucra la participación de descargas electrostáticas, que probablemente activarían la liberación de factor de necrosis tumoral a (TNF-a) y desencadenaría la fagocitosis de adipocitos. Actualmente no tiene un tratamiento médico, siendo las medidas preventivas de mitigación de los factores previamente mencionados las que producen una reversión de la lesión. Por otro lado, la presencia de estos brotes generan un gran impacto mediático por lo que también debe ser abordada comunicacionalmente. La presente revisión pretende sintetizar la literatura sobre el tema para exponer el conocimiento actual y lograr una noción de esta nueva enfermedad, tras su primera presentación en brote en nuestro país.

Lipoatrophia semicircularis (LS) (also known as "Semicircular lipoa-trophy") is an idiopathic disease, which is characterized by a reversible and localized atrophy, either total or partial, of subcutaneous adipose tissue and located in areas of skin contact with the real estate tips. It is characterized by appearing in endemic outbreaks whose only common factor is the workplace. Its causes are unknown, but currently associated factors have been proposed, such as: the contact area with the office furniture, the presence of electromagnetic radiation, electrostatic discharge and presence of low relative humidity. A current model to explain the pathogenesis of this disease involves the participation of electrostatic discharges, which probably activate the release of tumor necrosis factor a (TNF-a) and it would trigger phagocytosis of adipocytes. Currently there is no medical treatment, being proactive mitigation measures of the before mentioned factors, those that produce a reversion of the injury. On the other hand, the presence of these buds generates great media impact so it must be also addressed from a communication standpoint. The present review aims to summarize the literature on the subject to present current knowledge and achieve a notion of this new disease, after its first appearance in outbreak in our country.

[Studies on the electrostatic interactions between beta -lactoglobulin and tragacanthin: the first step towards fabrication of biopolymeric micro- and nanoparticles]

Investigation of the colloidal behaviour of protein-polysaccharide systems is becoming increasingly important to provide a foundation for their applications in areas such as production of biopolymer micro-and nano-particles, designing food analogues, and microencapsulation technology. The aim of the present study was to investigate the pH-induced critical transitions during associative phase separation between beta -lactoglobulin [BLG] and tragacanthin [T]. The formation of electrostatic complexes in BLG/T dispersions [0.3wt.% total concentration; BLG:T ratio 2:1] was investigated as a function of pH [2.00-6.00] by spectrophotometry and particle size analysis. In addition, coupling of slow in situ acidification of the blend, with gluconodelta-lacton, and rheometry were used to monitor the structural transitions during the associative phase separation. The influence of salt type and concentration on the formation of micro-particles were also determined. The formation of soluble complexes started at pH -5.20, and at pH -4.85 the aggregation of intrapolymeric complexes occurred, followed by a bulk phase separation at pH -4.30. The data indicated that coacervation occurred at pH 4.15. Finally, the mixture returned to a mono-phasic system at pH 2.5. Particle size analysis showed that the assembled structures experienced a contraction process upon complexation. Rheometry provided deeper insights into the colloidal behaviour of the system and the results were in good agreement with quiescent pH-induced transitions established by HCl titration. The formation of the micro-particles was strongly salt-dependent. Under controlled pH conditions, electrostatic interactions between beta -lactoglobulin and tragacanthin can be used to form a variety of biopolymer particles. These biopolymeric micro- and nanoparticles may be used in the food industry as natural delivery systems or fat-replacers

Regulation of chondrosarcoma cell growth using synthesized hydrogels with different electric charges / 生物医学工程学杂志

To develop standard in vitro chondrosarcoma models, we synthesized three hydrogels (i. e., PDMAAm, PNaAMPS and PMETAC) and investigated the influence of Young's modulus, swelling ratio and electric charges on the behavior of chondrosarcoma cells seeded on the hydrogels, including morphology, adhesion and aggregation. Results showed that the morphology of chondrosarcoma cells at 6h was dependent on the charges of hydrogels; cells present spindle-shaped and round-shaped morphology on negative charged and neutral hydrogel, respectively, while no cells spreaded on positive charged hydrogel. Chondrosarcoma cells formed aggregates on neutral PDMAAm after further culture. The hydrogels can be synthesized easily and has the characteristics of ease at use with defined components, which holds great potential for developing standard chondrosarcoma models in vitro.

Flexible interwoven termini determine the thermal stability of thermosomes

Group II chaperonins, which assemble as double-ring complexes, assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner. The molecular mechanism of group II chaperonin assembly and thermal stability is yet to be elucidated. Here, we selected the group II chaperonins (cpn-α and cpn-β), also called thermosomes, from Acidianus tengchongensis and investigated their assembly and thermal stability. We found that the binding of ATP or its analogs contributed to the successful assembly of thermosomes and enhanced their thermal stabilities. Cpn-β is more thermally stable than cpn-α, while the thermal stability of the hetero thermosome cpn-αβ is intermediate. Cryo-electron microscopy reconstructions of cpn-α and cpn-β revealed the interwoven densities of their non-conserved flexible N/C-termini around the equatorial planes. The deletion or swapping of their termini and pH-dependent thermal stability assays revealed the key role of the termini electrostatic interactions in the assembly and thermal stability of the thermosomes.

Structure analysis of the extracellular domain reveals disulfide bond forming-protein properties of Mycobacterium tuberculosis Rv2969c

Disulfide bond-forming (Dsb) protein is a bacterial periplasmic protein that is essential for the correct folding and disulfide bond formation of secreted or cell wallassociated proteins. DsbA introduces disulfide bonds into folding proteins, and is re-oxidized through interaction with its redox partner DsbB. Mycobacterium tuberculosis, a Gram-positive bacterium, expresses a DsbA-like protein ( Rv2969c), an extracellular protein that has its Nterminus anchored in the cell membrane. Since Rv2969c is an essential gene, crucial for disulfide bond formation, research of DsbA may provide a target of a new class of anti-bacterial drugs for treatment of M.tuberculosis infection. In the present work, the crystal structures of the extracellular region of Rv2969c (Mtb DsbA) were determined in both its reduced and oxidized states. The overall structure of Mtb DsbA can be divided into two domains: a classical thioredoxin-like domain with a typical CXXC active site, and an α-helical domain. It largely resembles its Escherichia coli homologue EcDsbA, however, it possesses a truncated binding groove; in addition, its active site is surrounded by an acidic, rather than hydrophobic surface. In our oxidoreductase activity assay, Mtb DsbA exhibited a different substrate specificity when compared to EcDsbA. Moreover, structural analysis revealed a second disulfide bond in Mtb DsbA, which is rare in the previously reported DsbA structures, and is assumed to contribute to the overall stability of Mtb DsbA. To investigate the disulphide formation pathway in M.tuberculosis, we modeled Mtb Vitamin K epoxide reductase (Mtb VKOR), a binding partner of Mtb DsbA, to Mtb DsbA.

Tip-to-tip interaction in the crystal packing of PACSIN 2 is important in regulating tubulation activity

The F-BAR domain containing proteins PACSINs are cytoplasmic phosphoproteins involved in various membrane deformations, such as actin reorganization, vesicle transport and microtubule movement. Our previous study shows that all PACSINs are composed of crescent shaped dimers with two wedge loops, and the wedge loop-mediated lateral interaction between neighboring dimers is important for protein packing and tubulation activity. Here, from the crystal packing of PACSIN 2, we observed a tight tip-to-tip interaction, in addition to the wedge loop-mediated lateral interaction. With this tip-to-tip interaction, the whole packing of PACSIN 2 shows a spiral-like assembly with a central hole from the top view. Elimination of this tip-to-tip connection inhibited the tubulation function of PACSIN 2, indicating that tip-to-tip interaction plays an important role in membrane deformation activity. Together with our previous study, we proposed a packing model for the assembly of PACSIN 2 on membrane, where the proteins are connected by tip-to-tip and wedge loop-mediated lateral interactions on the surface of membrane to generate various diameter tubules.

Crystal structure of the ubiquitin-like domain of human TBK1

TANK-binding kinase 1 (TBK1) is an important enzyme in the regulation of cellular antiviral effects. TBK1 regulates the activity of the interferon regulatory factors IRF3 and IRF7, thereby playing a key role in type I interferon (IFN) signaling pathways. The structure of TBK1 consists of an N-terminal kinase domain, a middle ubiquitin-like domain (ULD), and a C-terminal elongated helical domain. It has been reported that the ULD of TBK1 regulates kinase activity, playing an important role in signaling and mediating interactions with other molecules in the IFN pathway. In this study, we present the crystal structure of the ULD of human TBK1 and identify several conserved residues by multiple sequence alignment. We found that a hydrophobic patch in TBK1, containing residues Leu316, Ile353, and Val382, corresponding to the "Ile44 hydrophobic patch" observed in ubiquitin, was conserved in TBK1, IκB kinase epsilon (IKKɛ/IKKi), IκB kinase alpha (IKKα), and IκB kinase beta (IKKβ). In comparison with the structure of the IKKβ ULD domain of Xenopus laevis, we speculate that the Ile44 hydrophobic patch of TBK1 is present in an intramolecular binding surface between ULD and the C-terminal elongated helices. The varying surface charge distributions in the ULD domains of IKK and IKK-related kinases may be relevant to their specificity for specific partners.

Semen-derived enhancer of viral infection--a key factor in sexual transmission of HIV / 病毒学报

Semen-derived enhancer of viral infection(SEVI) is a peptide fragment (PAP248-286) from prostatic acid phosphatase(PAP), which can enhance human immunodeficiency virus infection. The mechanisms of SEVI include: (1) SEVI with several cationic amino acid residues reduced electrostatic repulsion between HIV virus and the target cells; (2) The disorder state of SEVI in the human body fluids was helpful to the interaction between virus and the target cell membranes; (3) SEVI could capture HIV particles directly and speed the velocity of virus on the surface of the target cells and improve adsorption and fusion. Currently, the substances of inhibiting SEVI activity include: EGCG from green tea, small molecule compound of aminoquinoline Surfen, ThT analogs BTA-EG6. Those compounds might block the combination of HIV and SEVI or prevent the formation of amyloid fibers, and then reduce the enhancement of SEVI. The studies on the biological characteristics and mechanisms of SEVI have a big benefit for the prevention and treatment of HIV infection.

Prova broncodilatadora na espirometria: efeito do uso de espaçador de grande volume com tratamento antiestático na resposta ao broncodilatador / Spirometry with bronchodilator test: effect that the use of large-volume spacers with antistatic treatment has on test response

OBJETIVO: Avaliar se o uso de salbutamol inalatório através de inalador dosimetrado acoplado a espaçadores de grande volume com tratamento antiestático na espirometria com prova broncodilatadora modifica os resultados do teste quando comparado à técnica usual (sem espaçador). MÉTODOS: Estudo prospectivo envolvendo 24 pacientes, com idades entre 18 e 45 anos e suspeita clínica de asma, atendidos no Ambulatório de Pneumologia do Hospital das Clínicas da Universidade Federal de Minas Gerais, em Belo Horizonte (MG). Os pacientes foram submetidos a duas espirometrias com prova broncodilatadora realizadas com e sem o uso de espaçador de grande volume. RESULTADOS: Não houve diferença significativa na variação do VEF1 antes e após o uso de broncodilatador entre as duas técnicas (ΔVEF1 média = 0,01 L; IC95 por cento: -0,05 a 0,06; p = 0,824). Não houve diferença estatisticamente significativa entre as duas técnicas em relação ao resultado qualitativo da prova broncodilatadora (p = 1,00). Houve concordância dos resultados da prova broncodilatadora entre as técnicas (coeficiente kappa = 0,909; p < 0,005). CONCLUSÕES: De acordo com os resultados deste estudo, a utilização de espaçadores de grande volume não modificou de forma significativa os resultados da prova broncodilatadora.

OBJECTIVE: To evaluate whether the use of inhaled albuterol via a metered-dose inhaler with a large-volume spacer with antistatic treatment modifies the bronchodilator test results when compared with the usual technique (no spacer). METHODS: A prospective study involving 24 patients, 18-45 years of age, clinically suspected of having asthma, and under treatment at the Outpatient Pulmonary Clinic of the Federal University of Minas Gerais Hospital das Clínicas, located in the city of Belo Horizonte, Brazil. All of the patients underwent two bronchodilator tests: one with and one without the use of a large-volume spacer. RESULTS: There was no significant difference in the variation of FEV1 prior to and after bronchodilator use between the two techniques (mean ΔFEV1 = 0.01 L; 95 percent CI: -0.05 to 0.06; p = 0.824). No statistically significant difference was found between the two techniques regarding the qualitative results on the bronchodilator test (p = 1.00). There was concordance between the techniques in terms of the bronchodilator test results (kappa coefficient = 0.909; p < 0.005). CONCLUSIONS: According to the results of this study, the use of large-volume spacers does not significantly modify bronchodilator test results.

Desenvolvimento de um dispositivo eletrônico para atração de gotas da pulverização eletrostática em plantas cítricas / Development of an electronic device for attraction drops of the electrostatic spraying in citric plants

Este trabalho teve como objetivo desenvolver um dispositivo para promover a atração de gotas carregadas eletricamente para o interior do dossel de plantas cítricas, visando reduzir o impacto ambiental causado pelos agrotóxicos. Foram distribuídos condutores metálicos no interior do dossel das plantas da laranja Pêra, com o propósito de atrair as gotas. Assim como etiquetas hidrossensíveis nos terços superiores, médios e inferiores, em três profundidades do dossel. As pulverizações foram realizadas com e sem carga, combinadas com a presença e ausência do dispositivo proposto. A eficiência da pulverização eletrostática e do dispositivo proposto foi baseada na densidade de gotas que variou de 112 a 147 gotas cm-2 sem e com carga, respectivamente, e na cobertura que variou de 10,7% a 12, 1% na parte inferior e superior, nas diferentes regiões da planta, não ocorrendo diferenças significativas entre os tratamentos. Em todas as condições estudadas, a maior densidade de gotas e a maior cobertura foram obtidas na parte externa do dossel.

This study aimed to develop a device to promote the attraction of electrically charged droplets to the inner part of the citrus plants, to reduce the environmental impact caused by pesticides. Metallic conductors were distributed in the inner part of the orange Pear canopy, in order to attract the droplets. Water sensitive papers were distributed onto the upper, middle and bottom part of the plant, at three different depths of the canopy. The spraying was performed with and without charging, combined with the presence and absence of the proposed device. The efficiency of electrostatic spraying and the mechanism proposed was based onto the droplets density ranging from 112.08 to 146.76 cm- 2 droplets with and without charging, respectively, and onto the coverage ranged from 10.75 to 12.12 % in the inner and superior part, in different regions of the plant, not occurring significant difference between the treatments. In all conditions studied, the highest droplets density and coverage were obtained on the outer part of the canopy.

Aceclofenac delivery by microencapsulation using LBL self-assembly for delayed release

Colonic targeting has gained increasing interest over the past years, not just for the transport of drugs for the treatment of local diseases associated with the colon but also for its potential for transporting peptides and proteins, particularly low molecular weight peptide drugs. Without protection, such peptide drugs are usually digested within the gastric and small intestinal sections. In the present work Layer-By-Layer [LBL] self-assembly was utilized to make Aceclofenac single bilayer microcapsules produced by sequential adsorption of positively charged chitosan and negatively charged Pectin on the external surface of negatively charged Aceclofenac microcrystals. Taguchi approach was applied to determine the best concurrence of composition factors that is concentration of chitosan, pectin, centrifugation speed and incubation time. The microcapsules were characterized for encapsulation efficiency, particle size, zeta potential, scanning electron microscopy and in-vitro release kinetics. Surface electric potential of Aceclofenac microcrystals was found to be negative with zeta potential -1.39 mV, in acetate buffer of pH 4. The primary and the secondary deposit layer of chitosan and pectin was found to have a positive and negative charge with zeta potential of +5.57 mV and -22.8 mV respectively. The sequential changing of surface zeta potential after each deposition is a satisfactory indication of the LBL self-assembly of the oppositely charged polyelectrolytes. The average size and encapsulation efficiency of the optimized single bilayer microcapsules [F5] was found to be 20microm and 63.83%, respectively. The ex-vivo percentage cumulative drug release of [F5] in Phosphate buffer pH 6.8 containing 2-4% w/v colonic fecal matter of male albino rat was found to be 98.40%. The optimized batch of microcapsules showed first order release kinetics [R[2]= 0.950] in presence of colonic fecal matter