Repositório RCAAP

In this work, we report evidences that the association of phosphofructokinase and F-actin can be affected by insulin stimulation in rabbit skeletal muscle homogenates and that this association can be a mechanism of phos-phofructokinase regulation. Through co-sedimentation techniques, we observed that on insulin-stimulated tissues, approximately 70% of phosphofructokinase activity is co-located in an actin-enriched fraction, against 28% in control. This phenomenon is accompanied by a 100% increase in specific phosphofructokinase activity in stimulated homogenates. Purified F-actin causes an increase of 230% in phosphofructokinase activity and alters its kinetic parameters. The presence of F-actin increases the affinity of phosphofructokinase for fructose 6-phosphate nevertheless, with no changes in maximum velocity (Vmax). Here we propose that the modulation of cellular distribution of phosphofructokinase may be one of the mechanisms of control of glycolytic flux in mammalian muscle by insulin.

Pollen analysis of a sediment sample obtained at 222 cm from the top of a drilling core collected in the Bay of Guanabara, Rio de Janeiro, was used as a tool to obtain more knowledge about pre-historical human living and environment. 14C datation revealed the age of 4210 years B.P. Most frequent pollen grains came from plants like Alchornea (Euphorbiaceae), Celtis (Ulmaceae), Lecythidaceae, Meliaceae, Ochnaceae and spores from forest Pteridophyta. Palynology and environmental studies revealed that agricultural activities could not be detected. The dense tropical rain forest was the dominant vegetation occurring in this region.

The concept of microdomains in plasma membranes was developed over two decades, following observation of polarity of membrane based on clustering of specific membrane components. Microdomains involved in carbohydrate-dependent cell adhesion with concurrent signal transduction that affect cellular phenotype are termed "glycosynapse". Three types of glycosynapse have been distinguished: "type 1" having glycosphingolipid associated with signal transducers (small G-proteins, cSrc, Src family kinases) and proteolipids; "type 2" having O-linked mucin-type glycoprotein associated with Src family kinases; and "type 3" having N-linked integrin receptor complexed with tetraspanin and ganglioside. Different cell types are characterized by presence of specific types of glycosynapse or their combinations, whose adhesion induces signal transduction to either facilitate or inhibit signaling. E.g., signaling through type 3 glycosynapse inhibits cell motility and differentiation. Glycosynapses are distinct from classically-known microdomains termed "caveolae", "caveolar membrane", or more recently "lipid raft", which are not involved in carbohydrate-dependent cell adhesion. Type 1 and type 3 glycosynapses are resistant to cholesterol-binding reagents, whereas structure and function of "caveolar membrane" or "lipid raft" are disrupted by these reagents. Various data indicate a functional role of glycosynapses during differentiation, development, and oncogenic transformation.

Memory is measured by measuring retrieval. Retrieval is often triggered by the conditioned stimulus (CS); however, as known since Pavlov, presentation of the CS alone generates extinction. One-trial avoidance (IA) is a much used conditioned fear paradigm in which the CS is the safe part of a training apparatus, the unconditioned stimulus (US) is a footshock and the conditioned response is to stay in the safe area. In IA, retrieval is measured without the US, as latency to step-down from the safe area (i.e., a platform). Extinction is installed at the moment of the first unreinforced test session, as clearly shown by the fact that many drugs, including PKA, ERK and protein synthesis inhibitors as well as NMDA receptor antagonists, hinder extinction when infused into the hippocampus or the basolateral amygdala at the moment of the first test session but not later. Some, but not all the molecular systems required for extinction are also activated by retrieval, further endorsing the hypothesis that although retrieval is behaviorally and biochemically necessary for the generation of extinction, this last process constitutes a new learning secondary to the unreinforced expression of the original trace.

The mathematical model described by Dye (1996) condemned the epidemiological canine visceral leishma-niasis control campaign, considering it non-efficient. Using this model, we mathematically demonstrate that the control is not efficient, only at low values (rate at which latent and infectious dogs are lost by the destruction program) which match the canine seropositivity observed in the field by the immunofluorescency (IF) blood eluates analysis. With higher k values, corresponding to IF (k = 0.07) or ELISA ( k = 0.25) results in sera samples, the number of infectious dogs declines to a Ro =1 or Ro =0, respectively, interrupting the transmission and the advancement of epidemics. We also experimentally demonstrate that the dog removal, following the results of IF of sera, instead of eluates lead to a 57% (p < 0.005) decrease in canine cases and 87.5% (p < 0.005) in human cases. Our mathematical and experimental results indicate that the control campaign become more efficient by enhancing the sensitivity of the diagnostic assay.

The anatoical description of silici?ed Gymnospermae woods from Upper Triassic sequences of southernmost Paraná Basin (Brazil) has allowed the identi?cation of a new taxon: Sommerxylon spiralosus n.gen. et n.sp. Diagnostic parameters, such as heterocellular medulla composed of parenchymatous and sclerenchymatous cells, primary xylem endarch, secondary xylem with dominant uniseriate bordered pits, spiral thickenings in the radial walls of tracheids, medullar rays homocellular, absence of resiniferous canals and axial parenchyma, indicate its relationship with the family Taxaceae, reporting on the first recognition of this group in the Triassic on Southern Pangea. This evidence supports the hypothesis that the Taxaceae at the Mesozoic were not con?ned to the Northern Hemisphere.

Evidences of coastal erosion in Rio Grande do Sul have been obtained by three methods: (a) analysis of the long-term morphodynamics and stratigraphy of coastal barriers, (b) annual shoreline mapping using the Differential Global Positioning System (DGPS), and (c) local beach profile measurements. The first method reflects coastal erosion as continuity of the geological evolution in the last 5 ka, taking place mainly along the southern half of gentle coastal projections. The second method represents a shorter temporal scale and indicates that approximately 80% of the coast is eroding. Beach profiling has been measured in very few places that are distant from each other since the early 1990s; consequently, their results reflect local and very short time shoreline behavior. A critical evaluation of published data addressing coastal erosion in Rio Grande do Sul strongly suggests that short and long term negative balance on the sediment budget is the main cause of erosion along this coastline.

Approximate Entropy (ApEn), a model-independent statistics to quantify serial irregularities, was used to evaluate changes in sap flow temporal dynamics of two tropical species of trees subjected to water deficit. Water deficit induced a decrease in sap flow of G. ulmifolia, whereas C. legalis held stable their sap flow levels. Slight increases in time series complexity were observed in both species under drought condition. This study showed that ApEn could be used as a helpful tool to assess slight changes in temporal dynamics of physiological data, and to uncover some patterns of plant physiological responses to environmental stimuli.

Given a hypersurface M on a unit sphere of the Euclidean space, we define the cone based on M as the set of half-lines issuing from the origin and passing through M. By assuming that the scalar curvature of the cone vanishes, we obtain conditions under which bounded domains of such cone are stable or unstable.

In this note we will show that the inverse image under the stereographic projection of a circular torus of revolution in the 3-dimensional euclidean space has constant mean curvature in the unit 3-sphere if and only if their radii are the catet and the hypotenuse of an appropriate right triangle.

We show how to compute the number of reducible cubic scrolls of codimension 2 in (math blackboard symbol P)n incident to the appropriate number of linear spaces.

The light petroleum extract from the roots of Lonchocarpus muehlbergianus Hassl contained nine flavonoids, including six new ones. These are 2,4-cis-2,4,5,8-tetramethoxy-(2´´,3´´:6,7)-furanoflavan; 2,4-cis-4-hydroxy-2,5,8-trimethoxy-(2´´,3´´:6,7)-furanoflavan; 2,4-cis-2-prenyloxy-4,5,8-trimethoxy-(2´´,3´´:6,7)-fu-ranoflavan; 2,4-cis-2-prenyloxy-4-hydroxy-5,8-dimethoxy-(2´´,3´´:6,7)-furanoflavan; 2',5',6'-trimethoxy-9-(1,1-dimethylallyoxy)-[2´´,3´´:3´,4´]-furanochalcone; 5,6-dimethoxy-(2´´,3´´:7,8)-furanoflavone, identi-fied by analysis of their spectral data (UV, IR, ¹H and 13C NMR, 2D-NMR, NOE and MS). The natural occurrence of 2,4-dioxygenated flavan derivatives is being reported for the first time. Quantitative analysis of the petrol extract, by using reversed-phase HPLC, showed that the most abundant flavonoid in the extract is 2,4-cis-2,4,5,8- tetramethoxy-(2´´,3´´:6,7)-furanoflavan.

The specific concept of G. geckoides was initially ascertained based on a topotypical sample from Salvador, Bahia. Geographic differentiation was studied through the analysis of two meristic characters (tubercles in a paramedian row and fourth toe lamellae) and color pattern of 327 specimens from 23 localities. It is shown that the population from the southernmost locality, Mucugê, is markedly divergent in all characters studied. A Holocene refuge model is proposed to explain the pattern. A decision about the rank to be attributed to the Mucugê population is deferred until more detailed sampling is effected and molecular methods are applied.

A number of application for enzymes in organic solvents have been developed in chemical processing, food related conversions and analyses. The only unsolved problem related to nonaqueous enzymology is the notion that enzymes in organic solvent are mostly far less active than in water. Therefore, studies concerning the mechanisms by which enzymes are inactivated by organic solvents would reveal a clear understanding of the structure-function relationship of this phenomenon. Here we analyzed the effects of a series of alcohols (methanol, ethanol, 1-propanol and 2-propanol) and acetone on the activity of yeast inorganic pyrophosphatase. We observed that solvents inactivated the enzyme in a dose-dependent manner. This inactivation is also dependent on the hydrophobicity of the solvent, where the most hydrophobic solvent is also the most effective one. The I50 for inactivation by n-alcohols are 5.9±4, 2.7±1 and 2.5±1 M for methanol, ethanol and 1-propanol, respectively. Inactivation was less effective at 37C than at 5C, when the I50 for inactivation by methanol, ethanol and 1-propanol are 4.5±2, 2.1±2 and 1.7±1 M, respectively. Our proposal is that solvent binds to the enzyme structure promoting the inactivation by stabilizing an unfolded structure, and that this binding is through the hydrophobic regions of either the protein or the solvent.

Common variable immunodeficiency (CVID) is an immunological disorder characterized by defective antibody production, recurrent infections, most notably of the respiratory tract, autoimmune phenomena and cancer. Some CVID patients may also present disturbances of the cellular immune response such as a decrease in the number and proportion of different lymphocyte populations, diminished lymphoproliferative response to mitogens and antigens, altered production of cytokines, and deficient expression of cell-surface molecules. Most Brazilian CVID patients included in this study show a decrease in T and B lymphocyte counts in the peripheral blood. Furthermore, their lymphocytes are more susceptible to apoptosis following activation than normal individuals, and they have a decrease in the expression of activation molecules like CD25, CD69, CD40L and CD70. Moreover, they show a decreased synthesis of IL-4 and IL-5 in comparison with normal individuals. The increase in susceptibility to apoptosis following activation, may also be responsible for the decrease in the expression of activation molecules and CD40L, decrease in Th2 cytokines synthesis, and in the number of T and B circulating cells. In this study we discuss some of these immunological disturbances correlating them to the patients' clinical features and comparing our patients' findings to the literature.

Although mother-to-child HIV transmission prevention has slowed down pediatric HIV infection in developed countries, large numbers of infants still become infected in developing nations. Data on pediatric HIV infection is however largely scarce. In this study, we have overviewed clinical, laboratory and genotypic data from a large cohort of HIV-infected infants regularly followed at two pediatric HIV outpatient clinics in Rio de Janeiro, Brazil. Children on antiretroviral therapy, as well as drug-naïve, newly diagnosed infants were analyzed. Prevalence of drug resistance mutations, as well as immunological and virological responses to therapy were evaluated. Additionally, HIV-1 subtype frequencies and their distribution over the course of the epidemic were studied. We have found a high prevalence of mutations among ARV-experienced children, whereas mutations were absent in the drug-naïve group. Despite the high levels of resistance among treated infants, an important improvement of their immunological status was observed. HIV-1 subtype distribution followed the trends of the adult population, with the appearance of non-B subtypes and recombinant forms after 1990. To our knowledge, this is the largest pediatric cohort ever analyzed in Brazil, and the data provided is of paramount importance to a better understanding of HIV/AIDS evolution in pediatric settings.

We examined gap junction communication in an in vitro model of hematopoiesis, using the murine bone marrow stroma cell line S-17, and primary cultures of murine marrow-derived blood cell precursors. S-17 cells express several connexins, the major one being connexin 43. Connexin expression and formation of functional gap junctions is modulated by stroma cell density. Transfection of S-17 cells with a vector containing connexin 43 sense or anti-sense sequences increased or decreased, respectively, connexin 43 synthesis and intercellular dye coupling. Under these conditions, modulation of gap junction-mediated communication modified the growth pattern of stroma itself, as well as the ability of the stroma to sustain hematopoiesis. Increased connexin 43 expression was associated with a delay in differentiation of blood cells, resulting in increased production of hematopoietic precursors, while decreased connexin 43 expression elicited an accelerated differentiation of myeloid blood cell precursor cells. These results suggest that connexin-mediated coupling in the stroma modulates the ratio between proliferation and differentiation of hematopoietic precursors. We therefore propose that increased gap junction communication in the stroma elicits an enhanced production of immature bone marrow cells through the delay in their terminal differentiation, inducing consequently an extended proliferation period of blood cell precursors.

The article is aimed at discussing the theoretical grounds which support the diagnosis of solvent-related chronic encephalopathy in the field of the worker's mental health, having it as a target in this area. The psychiatric, neurological and labor health postulates which contribute to the multidisciplinary description of such diagnostic category are presented.

The Araçuaí belt corresponds to the external portion of the western half of the Araçuaí-West Congo Neopro-terozoic orogen. TheAraçuaí belt fringes the São Francisco craton to east and is separated from the crystalline core of the orogen by the Abre Campo geophysical discontinuity. The southern Araçuaí belt involves four major lithologic units: the Archean and Paleoproterozoic gneisses of the Mantiqueira Complex, the Pedra Dourada Charnockite, the Paleoproterozoic Borrachudos Granitoid, and the metavolcanosedimentary rocks of the Dom Silvério Group. The Dom Silvério Group occurs in a NNE-SSW striking belt and consists of a thick package of metapelitic rocks with intercalations of quartzites, amphibolites, meta-ultramafics, banded iron formations, gondites and marbles. All units of the southern Araçuaí belt underwent four syn-metamorphic phases of deformation in the course of the Brasiliano event. The first phase, synchronous to a regional amphibolite facies metamorphism, was associated to a general tectonic transport towards north along the left-lateral Dom Silvério shear zone and its low angle segment. The second and third phases represent progressive stages of a west directed shortening, which led to the development of local thrusts and pervasive folds in several scales. The fourth phase is extensional and reflects the collapse of the orogen.

Facies descriptions of the Codó Formation in the Grajaú area are provided for the first time, and its sedimentary characteristics compared to those from the Codó area to allow paleoenvironmental reconstructions. Deposits in the Grajaú area include evaporites, limestones and argillites bearing features indicative of a shallow, low energy, subaqueous, saline environment exposed to meteoric and/or capillary conditions. Flooding-evaporative concentration-desiccation cycles suggest a saline pan complex surrounded by extensive evaporitic mudflats. The location of the system, whether coastal or inland, is a matter open for debate. However, the later hypothesis is favored considering: 1. Sr isotopic data, with values higher than those expected for Late Aptian marine waters; 2. calcitic composition of limestones (instead of dolomitic and/or magnesitic as expected in coastal settings); and 3. presence of continental ostracods and lack of marine fauna. This interpretation is consistent with that proposed for UpperAptian deposits of the Codó area, but the depositional system there was one dominated by more stable, well-stratified, anoxic waters and evaporite precipitation in central lacustrine areas, while in the Grajaú area the salt pan was more oxygenated and ephemeral, with salt precipitation mainly in marginal areas or along surrounding mudflats.