Showing papers by "Federal University of Rio de Janeiro published in 2001"
TL;DR: As a general rule the ethanol extracts of plants belonging to the Verbenaceae family showed lower EC50 values than the other plant extracts, among the partitions, the more polar ones (ethyl acetate and n‐butanol) are those that generally have higher antioxidant activity (AA).
Abstract: Brazilian plant extracts belonging to 16 species of 5 different families (71 extracts) were tested against the stable DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free-radical. The ability to scavenge DPPH radical was measured in these experiments by the discoloration of the solution. Ginkgo biloba and rutin, commonly used as antioxidants for medical purposes, were used as standards. Based on our results, we can say that as a general rule the ethanol extracts of plants belonging to the Verbenaceae family showed lower EC50 values than the other plant extracts. Among the partitions, the more polar ones (ethyl acetate and n-butanol) are those that generally have higher antioxidant activity (AA). Copyright © 2001 John Wiley & Sons, Ltd.
1,986 citations
TL;DR: The advances in the use of isatins for organic synthesis during the last twenty-five years, as well as a survey of its biological and pharmacological properties are reported in this review and in the accompanying supplementary information.
Abstract: Isatins (1H-indole-2,3-dione) are synthetically versatile substrates, where they can be used for the synthesis of a large variety of heterocyclic compounds, such as indoles and quinolines, and as raw material for drug synthesis. Isatins have also been found in mammalian tissue and their function as a modulator of biochemical processes has been the subject of several discussions. The advances in the use of isatins for organic synthesis during the last twenty-five years, as well as a survey of its biological and pharmacological properties are reported in this review and in the accompanying supplementary information.
784 citations
TL;DR: It is demonstrated that nAChRs are targets for KYNA and suggest a functionally significant cross talk between the nicotinic cholinergic system and the kynurenine pathway in the brain.
Abstract: The tryptophan metabolite kynurenic acid (KYNA) has long been recognized as an NMDA receptor antagonist. Here, interactions between KYNA and the nicotinic system in the brain were investigated using the patch-clamp technique and HPLC. In the electrophysiological studies, agonists were delivered via a U-shaped tube, and KYNA was applied in admixture with agonists and via the background perfusion. Exposure (≥4 min) of cultured hippocampal neurons to KYNA (≥100 nm) inhibited activation of somatodendritic α7 nAChRs; the IC50 for KYNA was ∼7 μm. The inhibition of α7 nAChRs was noncompetitive with respect to the agonist and voltage independent. The slow onset of this effect could not be accounted for by an intracellular action because KYNA (1 mm) in the pipette solution had no effect on α7 nAChR activity. KYNA also blocked the activity of preterminal/presynaptic α7 nAChRs in hippocampal neurons in cultures and in slices. NMDA receptors were less sensitive than α7 nAChRs to KYNA. The IC50 values for KYNA-induced blockade of NMDA receptors in the absence and presence of glycine (10 μm) were ∼15 and 235 μm, respectively. Prolonged (3 d) exposure of cultured hippocampal neurons to KYNA increased their nicotinic sensitivity, apparently by enhancing α4β2 nAChR expression. Furthermore, as determined by HPLC with fluorescence detection, repeated systemic treatment of rats with nicotine caused a transient reduction followed by an increase in brain KYNA levels. These results demonstrate that nAChRs are targets for KYNA and suggest a functionally significant cross talk between the nicotinic cholinergic system and the kynurenine pathway in the brain.
764 citations
TL;DR: In this paper, a commodity-by-industry IO model was applied to the Brazilian economy to evaluate the total impacts of international trade on its energy use and CO2 emissions.
424 citations
01 Aug 2001
TL;DR: A catalog record for this book is available from the British Library as mentioned in this paper, where the catalog record can be found in the catalogue of the British Museum's Archives of Science and Technology.
Abstract: A catalog record for this book is available from the British Library.
419 citations
Journal Article•
TL;DR: In this paper, the authors examined whether cells with tumor-specific aberrant DNA-methylation might be found in the saliva of affected patients and tested 30 patients with primary head and neck tumors using methylation-specific PCR searching for promoter hypermethylation of the tumor suppressor gene p16 (CDKN2A), the DNA repair gene O6-methylguanine-DNA-methyltransferase (MGMT), and the putative metastasis-disorder gene death-associated protein kinase (DAP-K).
Abstract: Aberrant promoter hypermethylation is common in head and neck cancer and may be useful as a marker for cancer cells. We examined whether cells with tumor-specific aberrant DNA-methylation might be found in the saliva of affected patients. We tested 30 patients with primary head and neck tumors using methylation-specific PCR searching for promoter hypermethylation of the tumor suppressor gene p16 (CDKN2A), the DNA repair gene O6-methylguanine-DNA-methyltransferase (MGMT) and the putative metastasis suppressor gene death-associated protein kinase (DAP-K). Aberrant methylation of at least one of these genes was detected in 17 (56%) of 30 head and neck primary tumors; 14 (47%) of 30 at p16, 10 (33%) of 30 at Dap-K and 7 (23%) of 30 at MGMT. In 11 (65%) of 17 methylated primary tumors abnormal methylated DNA was detected in the matched saliva samples. Abnormal promoter methylation in saliva DNA was found in all tumor stages and more frequently in tumors located in the oral cavity. Moreover, none of the saliva from patients with methylation-negative tumors displayed methylation of any marker. Of 30 saliva samples from healthy control subjects (15 smokers and 15 nonsmokers), only one sample from a smoking patient was positive for DNA methylation at two target genes. Detection of aberrant promoter hypermethylation patterns of cancer-related genes in saliva of head and cancer patients is feasible and may be potentially useful for detecting and monitoring disease recurrence. Long-term longitudinal studies are needed to evaluate this approach for early detection of head and neck cancer in at-risk populations.
395 citations
TL;DR: Strengthening care for sick children referred to hospital should focus on achievable objectives with the greatest potential benefit for health outcome, and possible targets for improvement include initial triage, emergency care, assessment, inpatient treatment, and monitoring.
390 citations
TL;DR: Kinetic studies under pressure enable dissection of the roles of packing and cavities in folding, and in assembly of multimolecular structures such as protein-DNA complexes and viruses.
370 citations
TL;DR: It is suggested that the gut is an important source of candidemia, and studies that supported the skin as a source for this infection were surprisingly incomplete.
Abstract: The source of candidemia has been the subject of considerable debate, with some suggesting a origin in the gastrointestinal tract and others suggesting a skin origin. To evaluate the potential sources of candidemia, we performed a computerized search of the MEDLINE database for studies published from January 1966 through September 2000 and we identified relevant abstracts presented at national meetings. We reviewed the literature with special emphasis on studies that used appropriate definitions, evaluated both gut and skin as sources, and conducted molecular-relatedness studies. Among 203 candidemia studies published, we identified 21 that evaluated a specific source for candidemia and only 5 that performed molecular typing. Those studies and additional experimental, epidemiologic, and molecular-relatedness studies strongly suggested that the gut is an important source of candidemia, and studies that supported the skin as a source for this infection were surprisingly incomplete.
369 citations
TL;DR: It is demonstrated that microcystins can accumulate in fish tissue used for human consumption and rates of ingestion routinely exceed the TDI guidelines as set by the WHO for drinking water.
359 citations
TL;DR: P phenotypic co‐variance and correlation structure is compared among Platyrrhine Neotropical primates to help evaluate the evolution of relationships among traits in response to new functional and developmental relationships.
Abstract: Similarity of genetic and phenotypic variation patterns among populations is important for making quantitative inferences about past evolutionary forces acting to differentiate populations and for evaluating the evolution of relationships among traits in response to new functional and developmental relationships. Here, phenotypic covariance and correlation structure is compared among Platyrrhine Neotropical primates. Comparisons range from among species within a genus to the superfamily level. Matrix correlation followed by Mantel's test and vector correlation among responses to random natural selection vectors (random skewers) were used to compare correlation and variance/covariance matrices of 39 skull traits. Sampling errors involved in matrix estimates were taken into account in comparisons using matrix repeatability to set upper limits for each pairwise comparison. Results indicate that covariance structure is not strictly constant but that the amount of variance pattern divergence observed ...
01 Apr 2001
TL;DR: In this paper, aplicacao da metodologia de analise de redes sociais is discussed, a partir da apresentacao dos resultados de pesquisa desenvolvida junto a movimentos socias organizados nos suburbios da Leopoldina, na cidade do Rio de Janeiro.
Abstract: Discute-se sobre a aplicacao da metodologia de analise de redes sociais nos estudos do fluxo e transferencia da informacao, a partir da apresentacao dos resultados de pesquisa desenvolvida junto a movimentos sociais organizados nos suburbios da Leopoldina, na cidade do Rio de Janeiro. Para estudar os fluxos de informacao e as estruturas de comunicacao de grupos delimitados, procurou-se perceber como as informacoes circulam e sao empregadas como recurso nas lutas por melhores condicoes de vida. Foram aplicadas algumas medidas da metodologia de analise de redes sociais, combinadas com instrumentos da metodologia qualitativa. Conclui-se que, tal como apontou a analise de redes, alguns personagens sao responsaveis pela dinamizacao das redes, ocupando posicoes estrategicas, que lhes garantem, inclusive, o reconhecimento dos demais agentes. Alem disso, percebe-se que no interior dessas redes, na constante tensao entre as diferencas que ela comporta, formam-se “redes de conhecimentos”, que alimentam e redefinem constantemente as acoes.
TL;DR: In this article, a phenomenological theory is proposed, explicitly considering that particle moments interact through long-ranged dipolar random forces, whose effect is pictured in terms of a temperature ${T}^{*}, adding to the actual temperature T in the denominator of the Langevin function argument.
Abstract: The anhysteretic magnetization of the granular metallic alloy ${\mathrm{Cu}}_{90}{\mathrm{Co}}_{10}$ is experimentally studied over a wide temperature range (2--700 K). The measurements definitely exclude that this alloy is a simple superparamagnet, even in the high-temperature limit, although some features of granular systems [such as the typical Langevin-like form of the anhysteretic magnetization curves $M(H)]$ are often taken as evidence of superparamagnetism. A phenomenological theory is proposed, explicitly considering that particle moments interact through long-ranged dipolar random forces, whose effect is pictured in terms of a temperature ${T}^{*},$ adding to the actual temperature T in the denominator of the Langevin function argument. This simple formula explains all features of the experimental $M(H)$ curves. The theory indicates that the actual magnetic moments on interacting Co particles are systematically larger than those obtained fitting the magnetic data to a conventional Langevin function. The ${\mathrm{Cu}}_{90}{\mathrm{Co}}_{10}$ granular alloy is therefore identified as an ``interacting superparamagnet'' ISP. The ISP regime appears as separating the high-temperature, conventional superparamagnetic phase from the low-temperature, blocked-particle regime. In this way, a magnetic-regime diagram can be drawn for each granular system. The competition between single-particle and collective blocking mechanisms is briefly analyzed. The proposed interpretation is thought to be applicable to other fine particle systems; its main features and intrinsic limits are discussed.
TL;DR: The donor electron exchange in silicon and germanium is calculated and demonstrated, and an atomic-scale challenge for quantum computing in Si is demonstrated, as the six conduction-band minima in Si lead to intervalley electronic interference, generating strong oscillations in the exchange splitting of two-donor two-electron states.
Abstract: The silicon-based quantum computer proposal has been one of the actively pursued ideas during the past three years. Here we calculate the donor electron exchange in silicon and germanium, and demonstrate an atomic-scale challenge for quantum computing in Si (and Ge), as the six (four) conduction-band minima in Si (Ge) lead to intervalley electronic interference, generating strong oscillations in the exchange splitting of two-donor two-electron states. Donor positioning with atomic-scale precision within the unit cell thus becomes a decisive factor in determining the strength of the exchange coupling---a fundamental ingredient for two-qubit operations in a silicon-based quantum computer.
TL;DR: In this paper, a greedy randomized adaptive search procedure (GRASP) is applied to solve the transmission network expansion problem, and the best solution over all GRASP iterations is chosen as the result.
Abstract: A greedy randomized adaptive search procedure (GRASP) is a heuristic method that has shown to be very powerful in solving combinatorial problems. In this paper we apply GRASP to solve the transmission network expansion problem. This procedure is an expert iterative sampling technique that has two phases for each iteration. The first, construction phase, finds a feasible solution for the problem. The second phase, a local search, seeks for improvements on construction phase solution by a local search. The best solution over all GRASP iterations is chosen as the result.
TL;DR: In this article, the authors extended the BaSeL standard stellar library to non-solar metallicities, down to [Fe/H] ~ -2.0 dex, which is consistent simultaneously with both colour-temperature relations and colour-absolute magnitude diagrams.
Abstract: We extend the colour calibration of the widely used BaSeL standard stellar library (Lejeune, Cuisinier, & Buser 1997, 1998) to non-solar metallicities, down to [Fe/H] ~ -2.0 dex. Surprisingly, we find that at the present epoch it is virtually impossible to establish a unique calibration of UBVRIJHKL colours in terms of stellar metallicity [Fe/H] which is consistent simultaneously with both colour-temperature relations and colour-absolute magnitude diagrams (CMDs) based on observed globular cluster photometry data and on published, currently popular standard stellar evolutionary tracks and isochrones. The problem appears to be related to the long-standing incompleteness in our understanding of convection in late-type stellar evolution, but is also due to a serious lack of relevant observational calibration data that would help resolve, or at least further significant progress towards resolving this issue. In view of the most important applications of the BaSeL library, we here propose two different metallicity calibration versions: (1) the "WLBC 99" library, which consistently matches empirical colour-temperature relations and which, therefore, should make an ideal tool for the study of individual stars; and (2), the "PADOVA 2000" library, which provides isochrones from the Padova 2000 grid (Girardi et al., 2000) that successfully reproduce Galactic globular-cluster colour-absolute magnitude diagrams and which thus should prove particularly useful for studies of collective phenomena in stellar populations in clusters and galaxies.
TL;DR: It is suggested that a macromolecular complex of prion-DNA may act as an intermediate for the formation of the growing fiber, and host nucleic acid may modulate the delicate balance between the cellular and the misfolded conformations by reducing the protein mobility and by making the protein-protein interactions more likely.
TL;DR: The hippocampus, a limbic brain region involved in the encoding and retrieval of memory, has a well-defined structural network assembled from excitatory principal neurons and inhibitory interneuron...
Abstract: The hippocampus, a limbic brain region involved in the encoding and retrieval of memory, has a well-defined structural network assembled from excitatory principal neurons and inhibitory interneuron...
TL;DR: Methodological steps in the selection of questions on social networks and support for a cohort study of 4,030 employees from a public university in Rio de Janeiro suggest that social Networks and support will be adequately measured and will allow for the investigation of their associations with health outcomes in a Brazilian population.
Abstract: We describe methodological steps in the selection of questions on social networks and support for a cohort study of 4,030 employees from a public university in Rio de Janeiro. First, group discussions with volunteers were conducted to explore the adequacy of related concepts. Next, questions in the Medical Outcomes Study questionnaire were submitted to standard "forward-" and "back-translation" procedures. The questions were subsequently evaluated through five stages of pre-tests and a pilot study. No question had a proportion of non-response greater than 5%. Pearson correlation coefficients between questions were distant from both zero and unity; correlation between all items and their dimension score was higher than 0.80 in most cases. Finally, Cronbach Alpha coefficients were above 0.70 within each dimension. Results suggest that social networks and support will be adequately measured and will allow for the investigation of their associations with health outcomes in a Brazilian population.
TL;DR: TheLeishmanicidal effects of a chloroform fraction and a purified indole alkaloid obtained from crude stem extract of Peschiera australis against Leishmania amazonensis, a causative agent of cutaneous leishmaniasis in the New World are shown.
Abstract: In this study, we show the leishmanicidal effects of a chloroform fraction (CLF) and a purified indole alkaloid obtained from crude stem extract of Peschiera australis against Leishmania amazonensis, a causative agent of cutaneous leishmaniasis in the New World. In a bioassay-guided chemical fractionation, the leishmanicidal activity in CLF completely and irreversibly inhibited promastigote growth. This fraction was also active against amastigotes in infected murine macrophages. Chemical analysis of CLF identified an iboga-type indole alkaloid coronaridine as one of its major compounds. Coronaridine showed potent antileishmanial activity, inhibiting promastigote and amastigote growth. Promastigotes and amastigotes treated with CLF or coronaridine showed pronounced alterations in their mitochondria as assessed by transmission electron microscopy.
TL;DR: Although difficult and expensive, the public health dog control campaigns performed in Brazil reduced the incidence of ZVL and should be maintained since treatment of dogs is an unrealistic intervention, both because of its prohibitive cost and relatively poor effectiveness.
Abstract: Brazil is the only country endemic for zoonotic visceral leishmaniasis (ZVL) that regularly conducts epidemiologic and prophylactic control programs that involve the treatment of human cases, insect vector control, and the removal of seropositive infected dogs. This report reviews 60 studies reporting data on the efficacy of these recommended control tools and concludes that in Brazil 1) eradication of the disease in Minas Gerais was achieved by the concomitant use of the three control methods, 2) although seropositivity by an immunofluorescent assay is not completely related to infectiousness, the removal of seropositive dogs leads to a significant reduction of canine and human incidence, 3) improvement of the sensitivity of the diagnostic tool used for canine control should optimize the efficacy of control, and 4) although difficult and expensive, the public health dog control campaigns performed in Brazil reduced the incidence of ZVL and should be maintained since treatment of dogs is an unrealistic intervention, both because of its prohibitive cost and relatively poor effectiveness.
TL;DR: The data suggest that AtGRP-3 regulates Wak1 function through binding to the cell wall domain of Wak1 and that the interaction of Wak 1 with AtGRp-3 occurs in a pathogenesis-related process in planta.
TL;DR: The magnetic properties of the perovskite system have been investigated by ac susceptibility and dc magnetization measurements, including relaxation and aging studies as discussed by the authors, and the overall results show evidence for the gradual appearance of a cluster glass behavior.
Abstract: The dynamic magnetic properties of the distorted perovskite system ${\mathrm{La}}_{0.7\ensuremath{-}x}{\mathrm{Y}}_{x}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ $(0l~xl~0.15)$ have been investigated by ac susceptibility and dc magnetization measurements, including relaxation and aging studies. All investigated samples display a metal-insulator transition. As yttrium is added in the compounds the overall results show evidence for the gradual appearance of a cluster glass behavior. For the $x=0.15$ sample, magnetization measurements as a function of time at various temperatures show that the magnetic relaxation is maximum at a given temperature, well below the ferromagnetic transition. This maximum coincides in temperature with a frequency-dependent feature in the imaginary part of the ac susceptibility, associated with a freezing process. This is interpreted as due to ferromagnetic clusters, which grow with decreasing temperature down to a temperature at which they freeze due to severe intercluster frustration.
01 Sep 2001
TL;DR: In this paper, the authors present an empirical methodology based on experiences garnered over more than two decades of work by the Empirical Software Engineering Group at the University of Maryland and related organizations, for taking a newly proposed improvement to development processes from the conceptual phase through transfer to industry.
Abstract: There is a growing interest in empirical study in software engineering, both for validating mature technologies and for guiding improvements of less-mature technologies. This paper introduces an empirical methodology, based on experiences garnered over more than two decades of work by the Empirical Software Engineering Group at the University of Maryland and related organizations, for taking a newly proposed improvement to development processes from the conceptual phase through transfer to industry. The methodology presents a series of questions that should be addressed, as well as the types of studies that best address those questions. The methodology is illustrated by a specific research program on inspection processes for Object-Oriented designs. Specific examples of the studies that were performed and how the methodology impacted the development of the inspection process are also described.
TL;DR: Application of a procedure to identify Y-linked gene fragments from the unmapped residue of the whole genome sequencing effort results in five genes, which include three protein phosphatases, an occludin-related gene (ORY), and a coiled-coils gene (CCY).
Abstract: The heterochromatic state of the Drosophila Y chromosome has made the cloning and identification of Y-linked genes a challenging process. Here, we report application of a procedure to identify Y-linked gene fragments from the unmapped residue of the whole genome sequencing effort. Previously identified Y-linked genes appear in sequenced scaffolds as individual exons, apparently because many introns have become heterochromatic, growing to enormous size and becoming virtually unclonable. A TBLASTN search using all known proteins as query sequences, tested against a blastable database of the unmapped fragments, produced a number of matches consistent with this scenario. Reverse transcription–PCR and genetic methods were used to confirm those that are expressed, Y-linked genes. The five genes reported here include three protein phosphatases (Pp1-Y1, Pp1-Y2, and PPr-Y), an occludin-related gene (ORY), and a coiled-coils gene (CCY). This brings the total to nine protein-coding genes identified on the Drosophila Y chromosome. ORY and CCY may correspond, respectively, to the fertility factors ks-1 and ks-2, whereas the three protein phosphatases represent novel genes. There remains a strong functional coherence to male function among the genes on the Drosophila Y chromosome.
TL;DR: In this article, a mini packed-bed column was used for continuous biosorption of heavy metals from aqueous solutions, where the residual biomass of the alga Sargassum sp. was immobilized in a polymeric matrix to improve its physicochemical properties for continuous bio-sorption.
TL;DR: In this paper, the kinetics of CO2 reforming of methane was studied over Pt supported on Al2O3, ZrO2, and x% Zr O2/Al2O 3 (1≤x≤20 wt), and the catalysts were characterized using different techniques.
TL;DR: In this article, a coating of crystalline monetite oriented along the [112] axis was electrochemically deposited on titanium substrates and was subsequently converted to hydroxyapatite by immersion in alkaline solutions.
Abstract: Calcium phosphates have a wide range of pH stability, depending on their Ca/P ratio. Under physiological conditions (pH ≈7), the most stable calcium phosphate is hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 . Acidic calcium phosphates, like dicalcium phosphate, CaHPO 4 (monetite) and dicalcium phosphate dihydrate, CaHPO 4 ·2H 2 O (brushite), are thermodynamically unstable under pH values greater than 6–7 and undergo transformation into more stable calcium phosphates. It means that, when placed in vivo (pH ≈7), acidic calcium phosphates convert to hydroxyapatite. In the present study, a coating of crystalline monetite oriented along the [112] axis was electrochemically deposited on titanium substrates. This monetite coating was subsequently converted to hydroxyapatite by immersion in alkaline solutions. The result was a crystalline hydroxyapatite coating oriented along the [002] axis. Different alkaline solutions produced the same result. Studying the effect of immersion time on the transformation indicated that 4 h were required to complete the conversion from monetite to hydroxyapatite. The transformation occurred by a dissolution–reprecipitation mechanism, i.e. the monetite coating was continuously dissolved and reprecipitated as hydroxyapatite. This combined electrochemical deposition and chemical conversion process produced hydroxyapatite coatings with satisfactory adhesion to the substrate and a thickness between 10 and 30 μm.
TL;DR: In this article, the species composition of reef-fish assemblages from nine Brazilian major coastal sites and four oceanic islands are compared using Canonical corres- pondence analysis (CCA).
Abstract: The species composition of reef-fish assemblages from nine Brazilian major coastal sites and four oceanic islands are compared. Canonical corres- pondence analysis (CCA) was utilized to identify groups of sites based on similarity of composition, and to correlate environmental trends with such groups. Five distinct groups of sites were recog- nized: (1) the South and South-eastern coastal reefs (from Guarapari Islands to Santa Catarina, the southernmost Brazilian reefs); (2) the North- eastern coast (extending from the Manuel Luis Reefs to Abrolhos Archipelago); (3) Trindade Island; (4) Fernando de Noronha and Atol das Rocas; and (5) St Paul's Rocks. Water temper- ature, coral richness, distance from mainland, primary production and shelf width strongly correlated with the diversity and composition of the reef sites.