2,491 research outputs found
Stability improvement of the fatty acid binding protein Sm14 from S. mansoni by Cys replacement: Structural and functional characterization of a vaccine candidate
No full textThe Schistosoma mansoni fatty acid binding protein (FABP), SmA, is a vaccine candidate against, S. mansoni and F hepatica. Previously, we demonstrated the importance of a correct fold to achieve protection in immunized animals after cercariae challenge [[10]. C.R.R. Ramos, R.C.R. Figueredo, T.A. Pertinhez, M.M. Vilar, A.L.T.O. Nascimento, M. Tendler, I. Raw, A. Spisni, P.L. Ho, Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein: structural, functional and immunoprotection analysis. J. Biol. Chem. 278 (2003) 12745-12751]. Here we show that the reduction of vaccine efficacy over time is due to protein dimerization and subsequent aggregation. We produced the mutants Sm14-M20(C62S) and Sm14M20(C62V) that, as expected, did not dimerize in SDS-PAGE. Molecular dynamics calculations and unfolding experiments highlighted a higher structural stability of these mutants with respect to the wild-type. In addition, we found that the mutated proteins, after thermal denaturation, refolded to their active native molecular architecture as proved by the recovery of the fatty acid binding ability. Sm14-M20(C62V) turned out to be the more stable form over time, providing the basis to determine the first 3D solution structure of a Sm14 protein in its apo-form. Overall, Sm14-M20(C62V) possesses an improved structural stability over time, an essential feature to preserve its immunization capability and, in experimentally immunized animals, it exhibits a protection effect against S. mansoni cercariae infections comparable to the one obtained with the wild-type protein. These facts indicate this protein as a good lead molecule for large-scale production and for developing an effective Sm14 based anti-helminthes vaccine. (C) 2008 Elsevier B.V. All rights reserved.CAPESCNPqFAPESPFINEPALVOSFiocruz-RJ and Fundacao Butanta
NiO-nanoflowers decorating a plastic electrode for the non-enzymatic amperometric detection of H2O2 in milk: old issue, new challenge
No full textIn food supply chain, there are regulatory limitations on the use of chemicals for cleaning processing lines
since the healthiness of the commodities must be guaranteed if accidentally traces of these detergents and
sanitizers pass to them. Hydrogen peroxide, is a commonly used sanitizer in the cleaning of the food
processing lines having both bactericidal and bacteriostatic properties, however, it produces inflammatory
effects on the human body. The availability of rapid systems to detect its accidental presence is therefore
useful to speed up the control and apply corrective actions. In the present work, a drop casting and easily
prepared plastic graphite / PVC electrode decorated with NiO nanostructures has been investigated as
electrochemical sensor for the non-enzymatic amperometric determination of H2O2. 24 The catalytic activity,
dispersion, and stability of NiO nanostructures mixed with plastic nanocomposite electrode have been studied
in detail. The preparation method, particularly the precipitating agents used in the synthesis of NiO
nanostructures strongly influenced their morphology and porosity. Further, the electrochemical response of
NiO-PE electrodes towards H2O2 resulted to be morphology-dependent. The non-enzymatic electrochemical
sensor was optimized for the rapid and sensitive detection of H2O2 present in milk with no sample pre-
treatments. NiO nanoflowers showed the best catalytic activity towards H2O2, a linear range that extends up
to 4 mM and a LOD of 5 μM (3sd of the blank signal) were obtained
Molecular diagnosis of dermatophyte infections in dogs
No full textDermatophytes are fungi that can be contagious and cause skin infections of mammals, including humans. The etiological diagnosis of dermatophytic infection is usually performed using a combination of in vitro-culture and microscopic methods. However, in vitro culture requires long incubation time and it is frequently complicated by the presence of opportunistic fungi (e.g., species of Alternaria, Cladosporium, Mucor, Penicillium, Scopularopsis, Rhizopus and Chrysosporium), which can be present on the animal hair coat. Recent studies have demonstrated that first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) and the entire internal transcribed spacer region (ITS+) of nuclear ribosomal DNA as well as the chitin synthase 1 (chs1) gene are promising markers for selected species of dermatophytes. To date, the few studies attempting to specifically characterize dermatophytes from hair samples from dogs using PCR-based methodology relied on sequence-based analysis of selected genetic markers. The aim of the present study was to establish and evaluate a PCR-based approach employing genetic markers in nuclear DNA for the specific detection of dermatophytes on hair samples from dogs. Using 199 hair samples, we directly compared the test results of our one-step and nested-PCR assays with those based on conventional in vitro culture techniques (using the latter as the reference method).
The one step-PCR showed a low sensibility (62.2%) and very high specificity (96.6%) for the testing of samples from dogs and allowed the differentiation of Microsporum canis from other dermatophytes. The nested-PCR achieved higher sensibility (89.2%) and specificity (95.7%) and allowed the differentiation of M. canis from Trichophyton interdigitale (zoophilic) and geophilic dermatophytes (i.e. Microsporum gypseum or Trichophyton terrestre). The results provide practical tools for diagnostic applications to support clinicians in initiating prompt and targeted chemotherapy of canine dermatophytoses
NiO-nanoflowers decorating a plastic electrode for the non-enzymatic amperometric detection of H2O2 in milk: Old issue, new challenge
No full textIn food supply chain, there are regulatory limitations on the use of chemicals for cleaning processing lines since the healthiness of the commodities must be guaranteed if accidently traces of these detergents and sanitizers pass to them. Hydrogen peroxide, is a commonly used sanitizer in the cleaning of the food processing lines having both bactericidal and bacteriostatic properties, however, it produces inflammatory effects on the human body. The availability of rapid systems to detect its accidental presence is therefore useful to speed up the control and apply corrective actions. In the present work, a drop casting and easily prepared plastic graphite/PVC electrode decorated with NiO nanostructures has been investigated as electrochemical sensor for the non-enzymatic amperometric determination of H2O2. The catalytic activity, dispersion, and stability of NiO nanostructures mixed with plastic nanocomposite electrode have been studied in detail. The preparation method, particularly the precipitating agents used in the synthesis of NiO nanostructures strongly influenced their morphology and porosity. Further, the electrochemical response of NiO-PE electrodes towards H2O2 resulted to be morphology-dependent. The non-enzymatic electrochemical sensor was optimized for the rapid and sensitive detection of H2O2 present in milk with no sample pre-treatments. NiO nanoflowers showed the best catalytic activity towards H2O2, a linear range that extends up to 4 mM and a LOD of 5 μM (3sd of the blank signal) were obtained
Stand-alone plastic electrode based on phosphomolybdate electroactive complex for phosphate detection in environmental samples
No full textInorganic phosphate and coronary perfusion pressure mediate contractile dysfunction during mild ischemia
No full text During mild graded ischemia in perfused rat hearts, we (V.M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 1794-1802, 1992) previously found a relationship between decreased left ventricular developed pressure (LVDP) and increased Pi, in which intracellular pH, cytosolic Ca2+ concentration ([Ca2+]i), ATP, and free-energy change of ATP hydrolysis were not altered enough to affect contractility. However, the contribution of decreased coronary perfusion pressure (CPP) to decreased LVDP could not be determined. Thus, in the present study, graded hypoxia in perfused rat hearts (95-37.5% O2) was used to increase Pi to similar levels produced during mild ischemia without altering CPP and minimizing changes of other potential mediators of contractile dysfunction. 31P-magnetic resonance spectroscopy and indo 1 fluorescence were used to assess energy metabolites and [Ca2+]i, respectively. The relationship between LVDP and Pi during graded hypoxia was fit to a monoexponential (LVDP = 105 x e-0.04Pi). These data were compared with the relationship of LVDP and Pi during mild ischemia (LVDP = 106 x e-0.08Pi) (V. M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 1794-1802, 1992). The exponential constant, which describes the effect of Pi on LVDP, was 50% lower during graded hypoxia relative to mild ischemia. This suggests that another mediator, which accounted for approximately 50% of the decrease of LVDP during mild ischemia, was not present during hypoxia. Because CPP decreased during ischemia but not hypoxia, these data suggest that CPP and Pi contribute similarly in mediating contractile dysfunction during mild ischemia. </jats:p
Manejo neuroquirúrgico de los aneurismas intracraneales:análisis de los factores que influyen en el resultado final
No full textSin duda alguna que el desarrollo de la microcirug&iacute;a y otros avances, han permitido al neurocirujano ampliar notablemente el horizonte quir&uacute;rgico en el tratamiento de los aneurismas intracraneales. En el presente trabajo nuestro prop&oacute;sito es realizar una revisi&oacute;n de la experiencia acumulada en m&aacute;s de 15 a&ntilde;os, analizando como influyen los problemas en el diagn&oacute;stico cl&iacute;nico e imagenol&oacute;gico, el tratamiento inicial y la cirug&iacute;a en lograr la reducci&oacute;n m&aacute;xima posible de la morbilidad y mortalidad de esta enfermedad. En un medio neuroquir&uacute;rgico adecuado con acceso a tecnolog&iacute;a moderna se puede reducir la mortalidad a menos del 10% (9.09%), incluyendo casos con aneurismas complejos. Este trabajo se basa en un estudio descriptivo de 77 pacientes portadores de 101 aneurismas intracraneales intervenidos quir&uacute;rgicamente en el Centro de Investigaciones M&eacute;dico Quir&uacute;rgicas (CIMEQ), desde 1994 hasta el 2003. Se establecieron para el an&aacute;lisis factores favorables y de riesgo relacionados con la enfermedad y su tratamiento: edad, sexo, existencia de otras enfermedades asociadas, el estado neurol&oacute;gico al ingreso, la intensidad de la hemorragia, la cantidad de aneurismas encontrados en cada enfermo, la localizaci&oacute;n y anatom&iacute;a quir&uacute;rgica del saco, la presencia de complicaciones pre, trans y postoperatorias, el tiempo entre el diagn&oacute;stico de la enfermedad y la realizaci&oacute;n del proceder quir&uacute;rgico, as&iacute; como el empleo de coadyuvantes en la cirug&iacute;a. Se concluye que a&uacute;n no se realiza adecuadamente el diagn&oacute;stico inicial de la hemorragia subaracnoidea (HSA); la realizaci&oacute;n del estudio angiogr&aacute;fico completo a&uacute;n es demorado y la remisi&oacute;n del paciente a un centro para la atenci&oacute;n definitiva es tard&iacute;a, impidiendo la realizaci&oacute;n de la operaci&oacute;n en etapa temprana. Lo que ocurre durante la intervenci&oacute;n quir&uacute;rgica es definitorio en el resultado final por lo que se hace necesario contar con los elementos t&eacute;cnicos necesarios: microcirug&iacute;a, instrumental adecuado, surtido de grapas y otros m&eacute;todos coadyuvantes, que permitan obtener un resultado quir&uacute;rgico &oacute;ptimo de exclusi&oacute;n total aneurisma, manteniendo la circulaci&oacute;n cerebral. Se presenta un protocolo para el tratamiento de la enfermedad aneurism&aacute;tica que puede ser utilizado seg&uacute;n las condiciones y posibilidades de los diferentes servicios de neurocirug&iacute;a del pa&iacute;s
Cerium–Copper–Manganese Oxides Synthesized via Solution Combustion Synthesis (SCS) for Total Oxidation of VOCs
No full textAbstract: A set of cerium–manganese–copper oxide catalysts with various foreign metal contents was prepared via the solution combustion synthesis (SCS). The catalysts were characterized by complementary techniques such as N2 physisorption at − 196 °C, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), H2-temperature-programmed reduction (H2-TPR), O2-temperature-programmed desorption (O2-TPD) and X-ray photoelectron spectroscopy (XPS). Their catalytic activity was tested towards the VOC oxidation using ethylene and propylene as probe molecules. As a whole, it has been observed that the Ce55Mn45 sample (Mn 45 at.%), containing MnOx clusters interacting with the ceria phase, was the most active catalyst for propylene oxidation, exhibiting a complete conversion at 250 °C. On the other hand, the ternary oxide catalyst (Ce55Mn22.5Cu22.5 with Mn = 22.5 at.% and Cu = 22.5 at.%) has exhibited the best results for the oxidation of ethylene. These findings suggest that the co-presence of different active phases on the catalytic surface may have a beneficial (multiplicative) role on the whole reactivity. Finally, the most active powder catalysts were wash-coated in a SiC monolith and tested in a bench-scale reactor. As a whole, the catalyzed monoliths performed the complete oxidation of either ethylene or propylene at lower temperatures (550 and 450 °C, respectively) than those required to thermally decompose these molecules. Graphic Abstract: [Figure not available: see fulltext.]
Catalytic Oxidation of Soot and Volatile Organic Compounds over Cu and Fe Doped Manganese Oxides Prepared via Sol-Gel Synthesis
No full textA set of manganese oxide catalysts was synthesized and doped with Cu and/or Fe by means of the citric acid sol-gel preparation method. The samples were studied by means of several characterization techniques: field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), N2-physisorption at -196 °C, H2 and soot temperature-programmed reduction (H2-TPR, soot-TPR) and X-ray photoelectron spectroscopy (XPS). The catalytic performance of the prepared catalysts was investigated in the oxidation of a probe VOC molecule (propylene) and carbon soot singularly and simultaneously. The catalytic performances were studied as well assuring a content of 5 vol.% of water in the gaseous reactive mix. The investigations evidenced that the best soot catalytic oxidation rates occurred over the Mn2O3 sample, while the copper-doped manganese oxide (i.e. the MnCu15) showed the best performance in the decomposition of propylene. The soot conversion rates of the samples were positively correlated to the Mn3+/Mn2+ ratio of the samples, while the activity in the oxidation of propylene could be attributed to the reducibility enhancement caused by the insertion of Cu species in the structure of Mn2O3. The most active samples in soot oxidation demonstrated only a slight catalytic activity deactivation after thermal aging and practically no deactivation during the tests with humidity. Interestingly, the simultaneous soot-propylene oxidation tests evidenced an enhancement of the oxidation of soot particles in "tight"contact with the catalyst, likely due to a cooperative effect between soot and propylene oxidation
- …
