Showing papers by "Federal University of São Carlos published in 2012"

Guidelines for the use and interpretation of assays for monitoring autophagy

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.

Silver nanoparticles: a brief review of cytotoxicity and genotoxicity of chemically and biogenically synthesized nanoparticles

Abstract: In recent years interest in silver nanoparticles and their applications has increased mainly because of the important antimicrobial activities of these nanomaterials, allowing their use in several industrial sectors. However, together with these applications, there is increasing concerning related to the biological impacts of the use of silver nanoparticles on a large scale, and the possible risks to the environment and health. In this scenario, some recent studies have been published based on the investigation of potential inflammatory effects and diverse cellular impacts of silver nanoparticles. Another important issue related to nanoparticle toxicity in biological media is the capacity for increased damage to the genetic material, since nanoparticles are able to cross cell membranes and reach the cellular nucleus. In this regard, there is increasing interest in the analysis of potential nanoparticle genotoxicity, including the effects of different nanoparticle sizes and methods of synthesis. However, little is known about the genotoxicity of different silver nanoparticles and their effects on the DNA of organisms; thus further studies in this field are required. This mini-review aims to present and to discuss recent publications related to genotoxicity and the cytotoxicity of silver nanoparticles in order to better understand the possible applications of these nanomaterials in a safe manner. This present work concludes that biogenic silver nanoparticles are generally less cyto/genotoxic in vivo compared with chemically synthesized nanoparticles. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other organisms.

Theoretical Models for Surface Forces and Adhesion and Their Measurement Using Atomic Force Microscopy

Abstract: The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS), it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion. This review provides the theoretical and experimental background of afs, adhesion forces, intermolecular interactions and surface forces in air, vacuum and in solution.

Trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during a single-leg squat in males and females with and without patellofemoral pain syndrome.

Abstract: Study Design Controlled laboratory study using a cross-sectional design. Objectives To determine whether there are any differences between the sexes in trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during the performance of a single-leg squat in individuals with patellofemoral pain syndrome (PFPS) and control participants. Background Though there is a greater incidence of PFPS in females, PFPS is also quite common in males. Trunk kinematics may affect hip and knee function; however, there is a lack of studies of the influence of the trunk in individuals with PFPS. Methods Eighty subjects were distributed into 4 groups: females with PFPS, female controls, males with PFPS, and male controls. Trunk, pelvis, hip, and knee kinematics and gluteal muscle activation were evaluated during a single-leg squat. Hip abduction and external rotation eccentric strength was measured on an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of v...

Caatinga revisited: ecology and conservation of an important seasonal dry forest.

Abstract: Besides its extreme climate conditions, the Caatinga (a type of tropical seasonal forest) hosts an impressive faunal and floristic biodiversity. In the last 50 years there has been a considerable increase in the number of studies in the area. Here we aimed to present a review of these studies, focusing on four main fields: vertebrate ecology, plant ecology, human ecology, and ethnobiology. Furthermore, we identify directions for future research. We hope that the present paper will help defining actions and strategies for the conservation of the biological diversity of the Caatinga.

Ecosystem services research in Latin America: The state of the art

Abstract: Ecosystem services science has developed at a fast rate in Latin America, a region characterized by a high biological and cultural diversity, strong emphasis in foreign investment, and high socioeconomic

Electronic structure, growth mechanism and photoluminescence of CaWO4 crystals

Abstract: In this paper, aggregated CaWO4 micro- and nanocrystals were synthesized by the co-precipitation method and processed under microwave-assisted hydrothermal/solvothermal conditions (160 °C for 30 min). According to the X-ray patterns, all crystals exhibited only the scheelite-type tetragonal structure. The data obtained by the Rietveld refinements revealed that the oxygen atoms occupy different positions in the [WO4] clusters, suggesting the presence of lattice distortions. The crystal shapes as well as its crystallographic orientations were identified by field-emission scanning electron microscopy and high-resolution transmission electron microcopy. Electronic structures of these crystals were evaluated by the first-principles quantum mechanical calculations based on the density functional theory in the B3LYP level. A good correlation was found between the experimental and theoretical Raman and infrared-active modes. A crystal growth mechanism was proposed to explain the morphological evolution. The ultraviolet-visible absorption spectra indicated the existence of intermediary energy levels within the band gap. The highest blue photoluminescence emission, lifetime and quantum yield were observed for the nanocrystals processed in the microwave-assisted solvothermal method.

Cluster Coordination and Photoluminescence Properties of alpha-Ag2WO4 Microcrystals

Abstract: In this paper, we report our initial research to obtain hexagonal rod-like elongated silver tungstate (α-Ag2WO4) microcrystals by different methods [sonochemistry (SC), coprecipitation (CP), and conventional hydrothermal (CH)] and to study their cluster coordination and optical properties. These microcrystals were structurally characterized by X-ray diffraction (XRD), Rietveld refinements, Fourier transform infrared (FT-IR), X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopies. The shape and average size of these α-Ag2WO4 microcrystals were observed by field-emission scanning electron microscopy (FE-SEM). The optical properties of these microcrystals were investigated by ultraviolet–visible (UV–vis) spectroscopy and photoluminescence (PL) measurements. XRD patterns and Rietveld refinement data confirmed that α-Ag2WO4 microcrystals have an orthorhombic structure. FT-IR spectra exhibited four IR-active modes in a range from 250 to 1000 cm–1. XANES...

An extended Lindley distribution

Abstract: In this paper we introduce an extension of the Lindley distribution which offers a more flexible model for lifetime data. Several statistical properties of the distribution are explored, such as the density, (reversed) failure rate, (reversed) mean residual lifetime, moments, order statistics, Bonferroni and Lorenz curves. Estimation using the maximum likelihood and inference of a random sample from the distribution are investigated. A real data application illustrates the performance of the distribution.

Low-level laser (light) therapy (LLLT) on muscle tissue: performance, fatigue and repair benefited by the power of light.

Abstract: The use of low level laser (light) therapy (LLLT) has recently expanded to cover areas of medicine that were not previously thought of as the usual applications such as wound healing and inflammatory orthopedic conditions. One of these novel application areas is LLLT for muscle fatigue and muscle injury. Since it is becom- ing agreed that mitochondria are the principal photoac- ceptors present inside cells, and it is known that muscle cells are exceptionally rich in mitochondria, this suggests that LLLT should be highly beneficial in muscle injuries. The ability of LLLT to stimulate stem cells and progenitor cells means that muscle satellite cells may respond well to LLLT and help muscle repair. Furthermore the ability of LLLT to reduce inflammation and lessen oxidative stress is also beneficial in cases of muscle fatigue and injury. This review covers the literature relating to LLLT and muscles in both preclinical animal experiments and human clini- cal studies. Athletes, people with injured muscles, and patients with Duchenne muscular dystrophy may all benefit.

Retrospectiva e tendência da alfacicultura brasileira

Abstract: A alface e considerada a principal hortalica folhosa no Brasil. Nas ultimas decadas, houve muitas mudancas quanto aos tipos varietais predominantes no pais bem como para a preferencia do uso de semente peletizada. O dominio do cultivo da alface lisa foi ate a decada de 90 com as cultivares do tipo 'manteiga' e 'Regina'. Posteriormente, houve uma mudanca para o tipo crespa e que, atualmente, corresponde ao principal segmento cultivado no Brasil. A ausencia de formacao de cabeca aliada a presenca de folhas flabeladas conferiram a esse tipo de alface uma melhor adaptacao no cultivo de verao com altas temperaturas e indices de pluviosidade. A preferencia brasileira pela alface crespa e um fato unico na alfacicultura mundial. A alface americana vem apresentando maiores indices de crescimento e aceitacao pelo mercado consumidor. Apesar de apresentar formacao de cabeca e que tem limitado seu cultivo no verao, na ausencia de cultivo protegido, suas folhas mais espessas tem conferido melhor sabor, crocância e durabilidade pos-colheita na alface americana. Alface com folha espessa e mandatoria para o mercado de processamento que apresenta alta tendencia de crescimento. Consideracoes sobre o melhoramento genetico para contribuir, pelo menos em parte, com essa situacao sao discutidas com o surgimento de novos tipos varietais tropicalizados, com a tendencia de segmentacao de mercado e da necessidade de uma cadeia pos-colheita mais eficiente.

Production planning and control for remanufacturing: literature review and analysis

Abstract: This article reviews the literature on production planning and control (PPC) for remanufacturing. The objectives are threefold: to determine whether the gaps identified by Guide (Guide Jr, V.D.R., 2000. Production planning and control for remanufacturing: industry practice and research needs. Journal of Operations Management, 18, 467–483) on the subject with respect to the main complicating characteristics of remanufacturing have been fulfilled; to classify the literature based on an appropriate structure to obtain a better understanding of the subject identifying sources of future research and to provide a useful source for scholars and practitioners. Seventy-six papers were examined and classified. It was found that none of the studies deals simultaneously with all of the complicating characteristics, and that more practical research is needed. In addition it was found that we lack studies regarding forecasting and aggregate planning considering disassembly of returned products, material matching restri...

Silver Distribution and Release from an Antimicrobial Denture Base Resin Containing Silver Colloidal Nanoparticles

Abstract: Purpose: The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. Materials and Methods: A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers’ instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Results: Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Conclusions: Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers.

Back-to-back Schottky diodes: the generalization of the diode theory in analysis and extraction of electrical parameters of nanodevices

Abstract: We report on the analysis of nonlinear current?voltage characteristics exhibited by a set of blocking metal/SnO2/metal. Schottky barrier heights in both interfaces were independently extracted and their dependence on the metal work function was analyzed. The disorder-induced interface states effectively pinned the Fermi level at the SnO2 surface, leading to the observed Schottky barriers. The model is useful for any two-terminal device which cannot be described by a conventional diode configuration.

Urea–Montmorillonite-Extruded Nanocomposites: A Novel Slow-Release Material

Abstract: The present study describes the preparation and characterization of a novel urea slow-release nanocomposite, based on urea intercalation into montmorillonite clay by an extrusion process at room temperature. Nanocomposites with urea contents ranging from 50 to 80 wt % were successfully produced and characterized. Analyses by XRD, DTA, and SEM-EDX confirmed the effectiveness of this simple process to exfoliate the clay lamellae into the urea matrix, forming a product that can be classified as a nanocomposite, due to the exfoliation degree attained. Diametral compression tests showed that the samples were very deformable, and the release rate of active components in water showed that the nanocomposite showed a slow release behavior for urea dissolution, even in low montmorillonite amounts (20% in weight).

Frontal plane biomechanics in males and females with and without patellofemoral pain.

Abstract: PurposeThe study’s purpose was to compare trunk, pelvis, hip, and knee frontal plane biomechanics in males and females with and without patellofemoral pain syndrome (PFPS) during stepping.MethodsEighty recreational athletes were equally divided into four groups: female PFPS, female controls,

Correlation between agar plate screening and solid-state fermentation for the prediction of cellulase production by Trichoderma strains.

Abstract: The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93 UI·g−1). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient () of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement.

Internal residual stresses in glass-ceramics: A review

Abstract: Internal residual stresses arise in glass-ceramics upon cooling down from the crystallization temperature. These stresses are due to the thermal expansion and the elastic mismatch between the crystalline and glassy phases. Therefore, the mechanical properties of glass-ceramics are likely to depend not only on their composition and microstructure but also on the type (tension or compression) and magnitude of these residual stresses. In this work, we critically review the most commonly used theoretical models concerning residual stresses in glass-ceramics and glass-matrix composites, taking into consideration the effects of crystallized volume fraction, crystal shape and thermal expansion anisotropy. We also discuss most of the reported measurements of residual stresses in these dual-phase materials using different techniques, such as X-ray diffraction, nuclear magnetic resonance, Raman and fluorescence spectroscopy, and indentation. The available models and experimental results regarding spontaneous microcracking due to residual stresses are also discussed. Finally, guidelines for future work are suggested.