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Search Results: 1 - 10 of 542296 matches for " Andréa Cristina Barbosa da;Cruz "
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Mineraliza??o de carbono e de nitrogênio provenientes de composto de lixo urbano em argissolo
Mantovani, José Ricardo;Ferreira, Manoel Evaristo;Cruz, Mara Cristina Pess?a da;Barbosa, José Carlos;Freiria, André Costa;
Revista Brasileira de Ciência do Solo , 2006, DOI: 10.1590/S0100-06832006000400008
Abstract: studies about nitrogen and carbon mineralization in soils amended with urban waste compost are important to evaluate the reactions of this waste in soil and to define the best rates for crops. two experiments were carried out under laboratory conditions to evaluate carbon and nitrogen mineralization in an ultisol fertilized with urban waste compost. the ultisol first experiment had a completely randomized design, with five urban waste compost rates of 0, 30, 60, 90, and 120 t ha-1 and three replicates. in the second experiment, n mineralization was evaluated at the same waste compost rates along eleven incubation periods (0, 7, 14, 28, 42, 56, 70, 84, 98, 112, and 126 days), in three replicates. the following results were obtained for a medium texture ultisol fertilized with urban waste compost: regardless of urban waste compost dose the greatest increase in n-no3- in the soil was found up to 42 days, stabilizing afterwards; the mineralization rate of organic carbon of less than 2 % in 168 days indicates that urban waste compost contributes to increase soil organic matter. in the absence of other n fertilizers, urban waste compost releases n to plants slowly at a rate of 12 % in 126 days, demonstrating its potential as slow-release nitrogen fertilizer.
Detection of oral streptococci in dental biofilm from caries-active and caries-free children
Silva, Andréa Cristina Barbosa da;Cruz, Jader dos Santos;Sampaio, Fábio Correia;Araújo, Demetrius Ant?nio Machado de;
Brazilian Journal of Microbiology , 2008, DOI: 10.1590/S1517-83822008000400009
Abstract: this work correlated the presence of oral streptococci in dental biofilm with clinical indexes of caries and oral hygiene in caries-active and caries-free children. s. mutans and/or s. sobrinus in the dental biofilm does not indicate a direct risk for developing dental caries.
Vaccine against Dental Caries: An Update  [PDF]
Diego Romário da Silva, Andréa Cristina Barbosa da Silva, Robeci Macedo Filho, Flaviana Dornela Verli, Sandra Aparecida Marinho
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.413103
Abstract:

Dental caries, the disease that causes tooth decay, is infectious, and the mutans streptococci bacteria have long been identified as the primary disease-causing agents. Caries vaccines showed promising results in experimental studies; however, it remains far the effective use in humans due to political-economic and ethical issues. Progress towards practical vaccine development requires evaluation of candidate vaccines in clinical trials. Promising strategies of passive immunization also require further clinical evaluation. The purpose of this chapter is to review the literature on the main research projects aimed at developing caries vaccines.

Influence of Sub-Lethal and Lethal Concentrations of Chlorhexidine on Morphology and Glucosyltransferase Genes Expression in Streptococcus mutans UA159  [PDF]
Andréa Cristina Barbosa da Silva, Rafael Nóbrega Stipp, Renata de Oliveira Mattos-Graner, Fábio Correia Sampaio, Demetrius Ant?nio Machado de Araújo
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.413105
Abstract: Chlorhexidine (CHX) is regarded as one of the most successful antiplaque agents in controlling the formation of dental biofilm. Nevertheless, molecular mechanisms of their effects in Streptococcus mutans are largely unknown. In this work, the effects of sub-lethal and lethal concentrations of chlorhexidine (CHX) on planktonic or biofilm-organized Streptococcus mutans cells were investigated in dose- and time-dependent manner. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) for planktonic cells and biofilm conditions were determined by standard methods. Quantitative PCR (qPCR) was used to quantify the relative levels of glucosyltransferase B (gtfB), gtfC and gtfD transcription of S. mutans in the presence of CHX. The CHX activity in the initial biofilm structure and morphological alterations in planktonic cells were examined by Scanning Electron Microscopy (SEM). The results indicate that CHX increased expression of gtfC and gtfD in planktonic S. mutans cells and CHX reduced the expression of gtfB, gtfC, and gtfD in biofilms. High concentrations of CHX resulted in several wilted S. mutans planktonic cells with spilled intracellular material, while decreased cells’ chain length and matrix was found when the initial biofilm was exposed to increasing concentrations of CHX. CHX’s effects against bacteria depend on the type of growth organization and the concentration and time of exposure to the drug. At sub-lethal concentrations, CHX affects the expression of glucosyltransferases, which may have anticariogenic effect.
Compara??o de procedimentos de quantifica??o de nitrato em tecido vegetal
Mantovani, José Ricardo;Cruz, Mara Cristina Pess?a da;Ferreira, Manoel Evaristo;Barbosa, José Carlos;
Pesquisa Agropecuária Brasileira , 2005, DOI: 10.1590/S0100-204X2005000100008
Abstract: nitrate content determination is important for food quality evaluation, but its determination is affected by interferences. the objective of this work was to compare nitrate determination procedures for vegetable tissues. in dry matter samples from three lettuce cultivars that received five levels of nitrogen in a greenhouse experiment, nitrate was extracted with deionized water and its determination was made by the cadmium column method, the distillation method, the salicylic acid method, and the method using the reductive mixture with zinc. the salicylic acid method and that of reductive mixture with zinc overestimated the nitrate content in lettuce dry matter, because they were influenced by the color of dry matter extracts and other interferences. the cadmium column and the distillation methods are the best for nitrate determination in vegetable tissues, but the simplicity and lower cost of distillation in relation to cadmium column method suggest that the first one must be recommended.
Mineraliza??o potencial e líquida de nitrogênio em solos
Yagi, Renato;Ferreira, Manoel Evaristo;Cruz, Mara Cristina Pess?a da;Barbosa, José Carlos;
Revista Brasileira de Ciência do Solo , 2009, DOI: 10.1590/S0100-06832009000200016
Abstract: the soil incubation methods can be used as tools to a better evaluation of n mineralization and availability. the objective of this study was to evaluate the potential and net soil organic n mineralization, and relate them to n availability to plants. twenty two soil samples (0-20 cm) were incubated at 35 oc for 30 weeks in aerobic conditions and at 40 oc for seven days in anaerobic conditions, and tested in a greenhouse experiment on corn plants. during the 30 weeks-incubation period n mineralization increased in the 2nd week, followed by a decrease and stabilization from the 4th week afterwards. the mineralized n data was adjusted to an exponential decay model and the accumulated n mineralized (nmac) data was adjusted to an exponential growth model and the potentially mineralizable n (n0) was then estimated. the quantities of n0 expressed n mineralization and availability in the long-term. however, the correlation of nmac with available n indicated by plants (n concentration and n uptake) was higher than of n0, and high correlation values were found after two weeks of incubation. this indicates that the statistical adjustment of data may be unnecessary and the incubation period can be reduced. the soil total n was a better indicator of the net and potential n organic mineralization than soil organic matter, especially in the long-term. the incubation for seven days in anaerobic conditions can be used to estimate no. the subtraction of initial n-nh4+ from the data obtained after incubation did not improve the estimation of n mineralization and availability by this method, which makes it even more simple and feasible.
Altera??es nos atributos de fertilidade em solo adubado com composto de lixo urbano
Mantovani, José Ricardo;Ferreira, Manoel Evaristo;Cruz, Mara Cristina Pess?a da;Barbosa, José Carlos;
Revista Brasileira de Ciência do Solo , 2005, DOI: 10.1590/S0100-06832005000500017
Abstract: urban waste compost is an organic manure frequently used in horticultural areas. thus, the objectives of this study were to evaluate the effects of urban waste compost on soil fertility, on lettuce production and on nutrient accumulation in plants. the experiment was carried out in a greenhouse using pvc columns. it was used a randomized block design with five treatments and eight replications. the treatments consisted of five urban waste compost rates (0; 30; 60; 90; and 120 t ha-1). the columns were filled up with soil from the 0-20 layer (treated with waste compost), 20-40 and 40-60 cm layer of a sandy-loam alfisol, and one lettuce seedling was planted. at the end of the first cycle, the rings of the columns of four replicates of each treatment were taken apart and another lettuce cultivation was carried out in the remaining four replicate columns. the urban waste compost incorporated at a depth of 0-20 cm improved the soil fertility in this layer and of the 20-40 cm layer, but caused no alteration in the characteristics at the 40-60 cm layer. fertilization with urban waste compost increased ph, om, p, k, ca, and mg in the 0-20 cm layer and ph and ca at a depth of 20-40 cm. the improvement of soil fertility with the urban waste compost application increased the lettuce yield and p, k and ca accumulation by plants.
Organic matter fractions and soil fertility under the influence of liming, vermicompost and cattle manure
Yagi, Renato;Ferreira, Manoel Evaristo;Cruz, Mara Cristina Pess?a da;Barbosa, José Carlos;
Scientia Agricola , 2003, DOI: 10.1590/S0103-90162003000300021
Abstract: this work evaluates effects of cattle manure vermicompost in association with liming on soil fertility indexes. the experiment was carried out in greenhouse conditions, in pots containing samples of a typic hapludox, medium-textured soil. five levels of vermicompost (equivalent to 0, 28, 42, 56, and 70 t ha-1, dry weight) and five liming levels (to raise base saturation to 20, 30, 40, 50, and 60%) were combined in a factorial scheme and samples were incubated for 180 days. samples of the same soil received the equivalent to 70 t ha-1 of the cattle manure used to produce the vermicompost, and the same lime rates. cattle manure was better than vermicompost to supply k and mg. small differences in p supply were observed between the manures. the vermicompost increased the levels of ca, ph, organic matter (om) and cec more than the manure. c-humic acids decreased and c-humin increased with vermicompost application. with liming, c-humic acids decreased, but the total content of om was not affected.
Organic matter fractions and soil fertility under the influence of liming, vermicompost and cattle manure
Yagi Renato,Ferreira Manoel Evaristo,Cruz Mara Cristina Pess?a da,Barbosa José Carlos
Scientia Agricola , 2003,
Abstract: This work evaluates effects of cattle manure vermicompost in association with liming on soil fertility indexes. The experiment was carried out in greenhouse conditions, in pots containing samples of a Typic Hapludox, medium-textured soil. Five levels of vermicompost (equivalent to 0, 28, 42, 56, and 70 t ha-1, dry weight) and five liming levels (to raise base saturation to 20, 30, 40, 50, and 60%) were combined in a factorial scheme and samples were incubated for 180 days. Samples of the same soil received the equivalent to 70 t ha-1 of the cattle manure used to produce the vermicompost, and the same lime rates. Cattle manure was better than vermicompost to supply K and Mg. Small differences in P supply were observed between the manures. The vermicompost increased the levels of Ca, pH, organic matter (OM) and CEC more than the manure. C-humic acids decreased and C-humin increased with vermicompost application. With liming, C-humic acids decreased, but the total content of OM was not affected.
In Silico Approach for the Identification of Potential Targets and Specific Antimicrobials for Streptococcus mutans  [PDF]
Andréa Cristina Barbosa da Silva, Diego Romário da Silva, Sabrina Avelar de Macêdo Ferreira, Gustavo Gomes Agripino, Allan Reis Albuquerque, Thaís Gaudencio do Rêgo
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.54045
Abstract:

Tooth decay affects most of the population in developed countries. The multifactorial etiology of the disease includes multiple bacterial species, S. mutans is the main pathogen associated with the disease. This bacterium adheres to the tooth surface and allows the colonization of other microorganisms resulting in dental biofilm. Several therapeutic agents are available to treat or prevent tooth decay, but none, with the exception of fluoride, has significantly influenced the disease’s global burden. Moreover, the probable development of resistance of microorganisms to existing antibacterial agents and the scarcity of good antimicrobial agents motivates this effort for innovation. The detailed knowledge obtained in recent years on the S. mutans allowed the identification of potential targets in this microorganism, enabling the development of specific drugs to combat tooth decay. Thus, the identification of potential targets in these pathogens is the first step in the discovery process of new therapeutic agents. Currently, the experimental assays used for this purpose are expensive and time consuming. In contrast, bioinformatics methods to predict drug targets are cheap, quick and workaday in the biotechnology. This article will review the potential drug targets in S. mutans, as well as the bioinformatics methods used to identify these targets and effective drugs for specific pharmacological treatment of dental caries.

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