Encontrados 13 documentos, a visualizar página 1 de 2
Genetic Characterization of an Insect-Specific Flavivirus Isolated from Culex T...
Parreira, R; Cookc, S; Lopes, A; Matos, AP; Almeida, AP; Piedade, J; Esteves, AWe describe the full genetic characterization of an insect-specific flavivirus (ISF) from Culex theileri (Theobald) mosquitoes collected in Portugal. This represents the first isolation and full characterization of an ISF from Portuguese mosquitoes. The virus, designated CTFV, for Culex theileri flavivirus, was isolated in the C6/36 Stegomyia albopicta (=Aedes albopictus) cell line, and failed to replicate in v...
Electrochemistry of nanoscale DNA surface films on carbon
Oliveira-Brett, A. M.; Paquim, A. M. Chiorcea; Diculescu, V. C.; Piedade, J. A. P.A DNA electrochemical biosensor is an integrated receptor-transducer device. The most important step in the development and manufacture of a sensitive DNA-biosensor for the detection of DNA-drug interactions is the immobilization procedure of the nucleic acid probe on the transducer surface. Magnetic A/C Mode atomic force microscopy (MAC Mode AFM) images in air were used to characterize two different procedures...
Atomic Force Microscopy and Anodic Voltammetry Characterization of a 49-Mer Die...
Chiorcea-Paquim, A. M.; Piedade, J. A. P.; Wombacher, R.; Jäschke, A.; Oliveira-Brett, A. M.Atomic force microscopy and differential pulse voltammetry were used to characterize the interaction of small highly structured ribozymes with two carbon electrode surfaces. The ribozymes spontaneously self-assemble in two-dimensional networks that cover the entire HOPG surface uniformly. The full-length ribozyme was adsorbed to a lesser extent than a truncated RNA sequence, presumably due to the formation of a...
Natural polymorphisms of HIV type 2 pol sequences from drug-naive individuals
Parreira, R.; Monteiro, F.; Pádua, E.; Piedade, J.; Venenno, T.; Paixão, M.T.; Esteves, A.Until today, the susceptibility of human immunodeficiency virus type 2 (HIV-2) to protease and nucleosidic reverse-transcriptase inhibitors (PI and NRTI, respectively) has not been clearly documented. In this report we studied HIV-2 proviral sequences (n = 30) from drug-naive patients. Our results revealed that several amino acid positions in the protease and reverse transcriptase coding sequence harbored resid...
Electrochemical sensing of the behaviour of oligonucleotide lipoplexes at charg...
Piedade, J. A. P.; Mano, M.; Lima, M. C. Pedroso de; Oretskaya, T. S.; Oliveira-Brett, A. M.Complexes between short oligodeoxynucleotides (ODN) with a variable dGxdCy base composition and liposomes composed of the cationic lipid DOTAP (ODN lipoplexes) were studied by differential pulse voltammetry at a glassy carbon electrode. Since lipoplexes are spontaneously formed by electrostatic interactions, the objective of the voltammetric study was to investigate their behaviour at the electrode surface/solu...
Voltammetric determination of all DNA nucleotides
Oliveira-Brett, A. M.; Piedade, J. A. P.; Silva, L. A.; Diculescu, V. C.The voltammetric oxidation of all deoxyribonucleic acid (DNA) monophosphate nucleotides is investigated for the first time over a wide pH range by differential pulse voltammetry with a glassy carbon electrode. Experimental conditions such as the electrode size, supporting electrolyte composition, and pH were optimized to obtain the best peak potential separation and higher currents. This enabled the simultaneou...
Voltammetric behaviour of oligonucleotide lipoplexes adsorbed onto glassy carbo...
Piedade, J. A. P.; Mano, M.; Lima, M. C. Pedroso de; Oretskaya, T. S.; Oliveira-Brett, A. M.The voltammetric behaviour of oligonucleotide lipoplexes (ODN-lipoplexes) prepared from short oligodeoxynucleotides (ODN), with different base compositions, and liposomes of the cationic lipid DOTAP, was studied by differential pulse voltammetry with a glassy carbon mini-electrode. It was found that the ODN base composition influences the ODN-lipoplex voltammetric response. Differential pulse voltammograms for ...
Electrochemical and Spectroscopic Studies of the Oxidation Mechanism of the Her...
Garrido, E. M.; Lima, J. L. F. C.; Delerue-Matos, C.; Borges, F.; Silva, A. M. S.; Piedade, J. A. P.; Brett, A. M. OliveiraElectrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil oc...
Spreading of HIV-1 subtype G and envB/gagG recombinant strains among injecting ...
Esteves, A; Parreira, R; Piedade, J; Venenno, T; Franco, M; Sousa, JG; Patrício, L; Brum, P; Costa, A; Canas-Ferreira, WWe have evaluated the genetic diversity of HIV-1 strains infecting injecting drug users (IDUs) in Lisbon, Portugal. Heteroduplex mobility assay and/or phylogenetic analysis revealed that env (C2V3C3 or gp41) subtype B is present in 63.7% of the 135 viral samples studied, followed by subtypes G (23.7%), A (6.7%), F (5.2%), and D (0.7%). Similar analysis of gag (p24/p7) performed on 91 of the specimens demonstrat...
Electrochemical detection of in situ adriamycin oxidative damage to DNA
Oliveira-Brett, A. M.; Vivan, M.; Fernandes, I. R.; Piedade, J. A. P.Adriamycin intercalation and in situ interaction with double helix DNA was investigated using a voltammetric DNA-biosensor. Oxidation and reduction of adriamycin molecules intercalated in double helix DNA were investigated in order to understand the in vivo mechanism of action with this anti-neoplasic drug. The results showed that the interaction of adriamycin with DNA is potential-dependent causing contact bet...
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