RESUMO
Topological crystalline insulators are a type of topological insulators whose topological surface states are protected by a crystal symmetry, thus the surface gap can be tuned by applying strain or an electric field. In this paper we predict by means of ab initio calculations a new phase of Bi which is a topological crystalline insulator characterized by a mirror Chern number nM = -2, but not a strong topological insulator. This system presents an exceptional property: at the (001) surface its Dirac cones are pinned at the surface high-symmetry points. As a consequence they are also protected by time-reversal symmetry and can survive against weak disorder even if in-plane mirror symmetry is broken at the surface. Taking advantage of this dual protection, we present a strategy to tune the band-gap based on a topological phase transition unique to this system. Since the spin-texture of these topological surface states reduces the back-scattering in carrier transport, this effective band-engineering is expected to be suitable for electronic and optoelectronic devices with reduced dissipation.
RESUMO
ABSTRACT The effect of aqueous extracts of Azadirachta indica A. Juss., Sapindus saponaria L., Nim + Piretro + Rotenona, Dimorphandra mollis and Stryph nodendron adstringens (Mart) Coville was evaluated in relation to non-preference for oviposition and feeding, attractiveness and biology of Plutella xylostella. For the experiment, leaf discs from cabbage (Brassica oleracea var. acephala) plants of the Butter cultivar were immersed in each extract at the concentration 10% (weight/volume) for 30 seconds. For the no-choice test the treatments that presented less attractiveness were the extracts of A. indica and D. mollis, and the consumption was lower in A. indica. The extracts of A. indica. S. saponaria. D. mollis and S. adstringens provided a deterrent effect on oviposition of P. xylostella. The treatments A. indica. S. saponaria and S. adstringens showed a negative effect for the biological parameters of the pest.
RESUMO Avaliou-se o efeito de Azadirachta indica A. Juss. (Nim), Sapindus saponaria L. (Sabão de soldado), Nim + Piretro + Rotenona, Dimorphandra mollis (Faveira) e Stryphnodendron adstringens (Mart) Coville (Barbatimão) em relação a não-preferência para oviposição e alimentação, atratividade e biologia de Plutella xylostella. Discos foliares de couve (Brassica oleracea var. acephala) cultivar Manteiga foram imersos em cada extrato à concentração de 10% (massa/volume) por 30 segundos para realização dos experimentos. Para o teste sem chance de escolha, os tratamentos que apresentaram menores atratividades foram os extratos de A. indica e D. mollis, e o menor consumo foi em A. indica. Os extratos de A. indica, S. saponaria D. mollis e S. adstringens proporcionaram efeito deterrente na oviposição de P. xylostella. Os tratamentos A. indica, S. saponaria e S. adstringens influênciaram negativamente os parâmetros biológicos da praga.
RESUMO
Avaliou-se o efeito de Azadirachta indica A. Juss. (Nim), Sapindus saponaria L. (Sabão de soldado), Nim + Piretro + Rotenona, Dimorphandra mollis (Faveira) e Stryphnodendron adstringens (Mart) Coville (Barbatimão) em relação a não-preferência para oviposição e alimentação, atratividade e biologia de Plutella xylostella. Discos foliares de couve (Brassica oleracea var. acephala) cultivar Manteiga foram imersos em cada extrato à concentração de 10% (massa/volume) por 30 segundos para realização dos experimentos. Para o teste sem chance de escolha, os tratamentos que apresentaram menores atratividades foram os extratos de A. indica e D. mollis, e o menor consumo foi em A. indica. Os extratos de A. indica, S. saponaria D. mollis e S. adstringens proporcionaram efeito deterrente na oviposição de P. xylostella. Os tratamentos A. indica, S. saponaria e S. adstringens influênciaram negativamente os parâmetros biológicos da praga.
The effect of aqueous extracts of Azadirachta indica A. Juss., Sapindus saponaria L., Nim + Piretro + Rotenona, Dimorphandra mollis and Stryph nodendron adstringens (Mart) Coville was evaluated in relation to non-preference for oviposition and feeding, attractiveness and biology of Plutella xylostella. For the experiment, leaf discs from cabbage (Brassica oleracea var. acephala) plants of the Butter cultivar were immersed in each extract at the concentration 10% (weight/volume) for 30 seconds. For the no-choice test the treatments that presented less attractiveness were the extracts of A. indica and D. mollis, and the consumption was lower in A. indica. The extracts of A. indica. S. saponaria. D. mollis and S. adstringens provided a deterrent effect on oviposition of P. xylostella. The treatments A. indica. S. saponaria and S. adstringens showed a negative effect for the biological parameters of the pest.
Assuntos
Extratos Vegetais , Controle Biológico de Vetores , Lepidópteros/crescimento & desenvolvimentoRESUMO
Neurologic events associated to antiphospholipoid syndrome (APLS) are not uncommon, but ischemic stroke due to acute carotid thrombosis, is a rare presentation of this syndrome. We report a case of a 48 years old female patient, without evidence of atherothrombosis or other vascular pathology, who presented an ischemic stroke due to acute thrombosis of the left internal carotid artery. The occlusion was diagnosed by Duplex scan and magnetic resonance angiography (Ds+MRA). The patient was anticoagulated and experienced total regression of her neurologic symptoms after a week. Ds+MRA were performed again and confirmed re-establishment of normal flow of internal carotid artery. A thorough clinical investigation confirmed the diagnosis of APLS (the association of a major thombotic event and high anticardiolipoid IgG antibody titers in three blood samples). The patient has been submitted to oral anticoagulation for three years and has not experienced new neurologic or thrombotic events.
Assuntos
Síndrome Antifosfolipídica/complicações , Trombose das Artérias Carótidas/etiologia , Estenose das Carótidas/etiologia , Acidente Vascular Cerebral/etiologia , Doença Aguda , Administração Oral , Anticoagulantes/administração & dosagem , Síndrome Antifosfolipídica/diagnóstico , Síndrome Antifosfolipídica/tratamento farmacológico , Trombose das Artérias Carótidas/diagnóstico , Trombose das Artérias Carótidas/tratamento farmacológico , Estenose das Carótidas/diagnóstico , Estenose das Carótidas/tratamento farmacológico , Feminino , Humanos , Angiografia por Ressonância Magnética , Pessoa de Meia-Idade , Prevenção Secundária , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/tratamento farmacológico , Resultado do Tratamento , Ultrassonografia Doppler DuplaRESUMO
RESUMEN: El Tití León Dorado, (Leontopithecus rosalia) es un primate (especie de los Tamarinos y Titíes) de la foresta atlántica brasileña en serio riesgo de extinción. Poco se conoce acerca de su anatomía, específicamente de las uniones musculares. Debido a ello, con el objetivo de comprender la locomoción de éste y otros primates, estudiamos la morfología y morfometría de los músculos grácil y sartorio y la relación entre ellos, en 3 especies de Leontopithecus rosalia. Se examinaron 18 animales adultos, de ambos sexos, sin anormalidades físicas en la región estudiada. El material pertenece a la colección del Centro de Primatología de Rio de Janeiro, Brasil. Los miembros posteriores fueron disecados hasta el nivel de los músculos grácil y sartorio, donde se efectuó la morfometría, obteniéndose, entre los músculos mencionados un área para su análisis histológico. Describimos la morfología de los músculos grácil y sartorio. Se obtuvieron valores promedio de la morfometría muscular y se estudió histológicamente la unión entre esos músculos. El análisis morfológico y morfométrico permite sugerir parámetros descriptivos de esos músculos. El análisis histológico permite concluir que las fibras del músculo grácil y del músculo sartorio no están fusionadas sino que se mantienen juntas a través de tejido conjuntivo, así, se insertan en el lado medial de la tibia. Funcionalmente, creemos que los músculos grácil y sartorio contribuyen a una activa contención de la articulación de la rodilla y sobre la biomecánica de los miembros posteriores de esos primates, conocidos como corredores.
Assuntos
Masculino , Adulto , Animais , Feminino , Callitrichinae/anatomia & histologia , Callitrichinae/crescimento & desenvolvimento , Callitrichinae/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/fisiologia , Músculo Esquelético/irrigação sanguínea , Desenvolvimento Muscular/fisiologia , Osso Púbico/anatomia & histologia , Osso Púbico/inervação , Osso Púbico/irrigação sanguíneaRESUMO
It has been demonstrated that the alpha2 chain of laminin-2 present on the surface of Schwann cells is involved in the process of attachment of Mycobacterium leprae to these cells. Searching for M. leprae laminin-binding molecules, in a previous study we isolated and characterized the cationic proteins histone-like protein (Hlp) and ribosomal proteins S4 and S5 as potential adhesins involved in M. leprae-Schwann cell interaction. Hlp was shown to bind alpha2-laminins and to greatly enhance the attachment of mycobacteria to ST88-14 Schwann cells. In the present study, we investigated the laminin-binding capacity of the ribosomal proteins S4 and S5. The genes coding for these proteins were PCR amplified and their recombinant products were shown to bind alpha2-laminins in overlay assays. However, when tested in ELISA-based assays and in adhesion assays with ST88-14 cells, in contrast to Hlp, S4 and S5 failed to bind laminin and act as adhesins. The laminin-binding property and adhesin capacity of two basic host-derived proteins were also tested, and only histones, but not cytochrome c, were able to increase bacterial attachment to ST88-14 cells. Our data suggest that the alanine/lysine-rich sequences shared by Hlp and eukaryotic H1 histones might be involved in the binding of these cationic proteins to laminin.
Assuntos
Proteínas de Bactérias/metabolismo , Laminina/metabolismo , Mycobacterium leprae/química , Proteínas Ribossômicas/metabolismo , Animais , Tatus , Aderência Bacteriana/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Clonagem Molecular , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Histonas/metabolismo , Humanos , Mycobacterium leprae/genética , Reação em Cadeia da Polimerase , Ligação Proteica/fisiologia , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/isolamento & purificação , Células de Schwann/microbiologia , Células de Schwann/fisiologiaRESUMO
It has been demonstrated that the alpha2 chain of laminin-2 present on the surface of Schwann cells is involved in the process of attachment of Mycobacterium leprae to these cells. Searching for M. leprae laminin-binding molecules, in a previous study we isolated and characterized the cationic proteins histone-like protein (Hlp) and ribosomal proteins S4 and S5 as potential adhesins involved in M. leprae-Schwann cell interaction. Hlp was shown to bind alpha2-laminins and to greatly enhance the attachment of mycobacteria to ST88-14 Schwann cells. In the present study, we investigated the laminin-binding capacity of the ribosomal proteins S4 and S5. The genes coding for these proteins were PCR amplified and their recombinant products were shown to bind alpha2-laminins in overlay assays. However, when tested in ELISA-based assays and in adhesion assays with ST88-14 cells, in contrast to Hlp, S4 and S5 failed to bind laminin and act as adhesins. The laminin-binding property and adhesin capacity of two basic host-derived proteins were also tested, and only histones, but not cytochrome c, were able to increase bacterial attachment to ST88-14 cells. Our data suggest that the alanine/lysine-rich sequences shared by Hlp and eukaryotic H1 histones might be involved in the binding of these cationic proteins to laminin
Assuntos
Humanos , Animais , Laminina/metabolismo , Mycobacterium leprae/metabolismo , Proteínas Ribossômicas/metabolismo , Tatus , Adesão Celular , Clonagem Molecular , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Histonas/metabolismo , Mycobacterium leprae/genética , Reação em Cadeia da Polimerase , Ligação Proteica/fisiologia , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/isolamento & purificação , Células de Schwann/fisiologiaRESUMO
The ability of Mycobacterium leprae to specifically bind alpha2-laminins of Schwann cells has been described recently as being an important property of the leprosy bacillus, which could explain the neural tropism of M. leprae. Therefore, the extent of the expression of alpha2-laminin-binding properties among mycobacteria was investigated. In an ELISA-based assay, all three species of Mycobacterium tested (M. tuberculosis, M. chelonae and M. smegmatis) expressed laminin-binding capacity, suggesting that the ability to bind alpha2-laminins is conserved within the genus Mycobacterium. This report also demonstrated that not only M. leprae but all the mycobacterial species tested readily interacted with the ST88-14 cells, a human schwannoma cell line, and that the addition of soluble alpha2-laminins significantly increased their adherence to these cells. These results failed to demonstrate the presence in M. leprae of a unique system based on alpha2-laminins for adherence to Schwann cells.
Assuntos
Aderência Bacteriana , Laminina/metabolismo , Mycobacterium/metabolismo , Células de Schwann/microbiologia , Animais , Humanos , Imuno-Histoquímica , Mycobacterium/fisiologia , Mycobacterium chelonae/metabolismo , Mycobacterium chelonae/fisiologia , Mycobacterium leprae/metabolismo , Mycobacterium leprae/fisiologia , Mycobacterium smegmatis/metabolismo , Mycobacterium smegmatis/fisiologia , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/fisiologia , Células Tumorais CultivadasRESUMO
It has recently been demonstrated that laminin alpha2 chains present on the surface of Schwann cells are involved in the process of attachment of Mycobacterium leprae to these cells. In this study, a protein in the M. leprae cell wall that was found to be capable of binding alpha2-containing laminins (merosin) was isolated and characterized. The M. leprae laminin-binding protein was identified as a 21-kDa histone-like protein (Hlp), a highly conserved cationic protein present in other species of mycobacteria. The gene that encodes this protein was PCR amplified, cloned, and expressed, and the recombinant protein was shown to bind alpha2-laminins. More significantly, when added exogenously, Hlp was able to greatly enhance the attachment of mycobacteria to ST88-14 human Schwann cells. The capacity to bind alpha2-laminins and to enhance mycobacterial adherence to Schwann cells was also found in other cationic proteins such as host-derived histones. Moreover, mutation in the hlp gene was shown not to affect the capacity of mycobacteria to bind to ST88-14 cells, suggesting that alternative adhesins and/or pathways might be used by mycobacteria during the process of adherence to Schwann cells. The potential role of Hlp as a fortuitous virulence factor contributing to the pathogenesis of M. leprae-mediated nerve damage is discussed.
Assuntos
Aderência Bacteriana , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Proteínas de Escherichia coli , Laminina/metabolismo , Mycobacterium leprae/fisiologia , Células de Schwann/microbiologia , Adesinas Bacterianas/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Clonagem Molecular , Humanos , Mutação , Mycobacterium leprae/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de AminoácidosRESUMO
Two extraction/clean-up analytical procedures were investigated and compared regarding their recovery and matrix-purification efficiency for screening beta2-agonist residues in fortified bovine urine by high-resolution gas chromatography-mass spectrometry (GC-MS). The first procedure, based on an analytical method originally developed for detecting anabolic steroids, consists of the employment of the nonionic resin, Amberlite XAD-2, a styrene-divinylbenzene copolymer for solid-phase extraction (SPE), followed by liquid-liquid extraction with diethyl ether. The second focuses on the use of a mixed SPE cartridge (reversed-phase and ion-exchange sorbent, Bond Elut Certify). In both cases, the trimethylsilylated derivatives were analyzed by GC-MS with an ion-trap detector. Clenbuterol, salbutamol, and terbutaline were used to spike urine samples during the comparison experimental phase. Afterwards, tulobuterol, mabuterol, mapenterol, cimbuterol, and brombuterol were included in the evaluation of the second procedure (the Bond Elut Certify procedure). At this stage, the detection was accomplished by GC-MS (quadrupole mass analyzer) with selective ion monitoring acquisition. The isotopic dilution method with the hexadeuterated analogues of clenbuterol and salbutamol was applied to prepare calibration curves and calculate recovery percentages. With XAD-2 resin, terbutaline and salbutamol (resorcinol and phenol-type beta2-agonists, respectively) could not be detected at 20 ng/mL or at 40 ng/mL. In spite of clenbuterol having been detected at 20 ng/mL, the results obtained were not reproducible. The use of the reversed-phase and ion-exchange sorbent Bond Elut Certify allowed multiresidue detection and showed several advantages for the screening of clenbuterol such as higher recoveries, cleaner final extracts, reduced sample preparation time, less labor intensive, and easier solvent consumption and disposal. Recoveries over 88% (concentrations ranging from 0.5 to 10 ppb) and limits of detection equal to 0.5 ppb were met for all the beta2-agonists studied with the last method.