966 resultados para cellulose modified with p-aminobenzoic groups


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The fabrication of supramolecular structures from the tetraruthenated porphyrin-containing phosphines, {TPyP[RuCl3(dppb)](4)}, RuTPyP, is demonstrated with Langmuir and Langmuir-Blodgett films. The surface pressure-molecular area isotherms (pi-A) point to an edge-on arrangement for the RuTPyP molecules in the condensed state. Weak aggregation in the Langmuir films was indicated by non-zero surface potentials at large areas per molecule and a slight red shift in the ultraviolet-visible absorption spectrum in comparison to the spectrum in solution. Further aggregation occurs in the Z-type Lang muir-Blodgett films, which was confirmed with ultraviolet-visible spectroscopy of the deposited films. Fourier transform infrared and Raman spectroscopic data for powder and Langmuir-Blodgett films indicate that the RuTPyP molecules are chemically stable in Langmuir-Blodgett films regardless of the contact with water during film fabrication. The nanostructured nature of the Langmuir-Blodgett films was manifested in cyclic voltammetry due to the high sensitivity of the metallic centers in RuTPyR Electrodes modified with Langmuir-Blodgett films exhibit an anodic peak at 100 mV and a cathodic peak at 7 mV, which is assigned to RuIII/RuII redox processes. Furthermore, Langmuir-Blodgett films from RuTPyP showed electrocatalytic activity for oxidation of benzyl alcohol, illustrated by a large shift of 100 mV in the anodic peak at 400 mV, while electropolymerized and cast films of the same compound displayed smaller and no activities, respectively.

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Apocynin has been used as an efficient inhibitor of the NADPH oxidase complex and its mechanism of inhibition is linked to prior activation through the action of peroxidascs. Here we studied the oxidation of apocynin catalyzed by myeloperoxidase (MPO) and activated neutrophils. We found that apocynin is easily oxidized by MPO/H2O2 or activated neutrophils and has as products dimer and trimer derivatives. Since apocynin impedes the migration of the cytosolic component p47phox to the membrane and this effect could be related to its conjugation with essential thiol groups, we studied the reactivity of apocynin and its MPO-catalyzed oxidation products with glutathione (GSH). We found that apocynin and its oxidation products do not react with GSH. However, this thiol compound was efficiently oxidized by the apocynin radical during the MPO-catalyzed oxidation. We suggest that the reactivity of apocynin radical with thiol compounds could be involved in the inhibitory effect of this methoxy-catechol on NADPH oxidase complex. (c) 2006 Elsevier B.V. All rights reserved.

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The piezoelectric quartz crystal resonators modified with oligonucleotide probes were used for detection of hepatitis C virus (HCV) in serum. The gold electrodes on either rough or smooth surface crystals were modified with a self-assembled monolayer of cystamine. After activation with glutaraldehyde, either avidin or streptavidin were immobilized and used for attachment of biotinylated DNA probes (four different sequences). Piezoelectric biosensors were used in a flow-through setup for direct monitoring of DNA resulting from the reverse transcriptase-linked polymerase chain reaction (RT-PCR) amplification of the original viral RNA. The samples of patients with hepatitis C were analyzed and the results were compared with the standard RT-PCR procedure (Amplicor test kit of Roche, microwell format with spectrophotometric evaluation). The piezoelectric hybridization assay was completed in 10 min and the same sensing surface was suitable for repeated use. (C) 2004 Elsevier B.V. All rights reserved.

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Purpose: This paper focuses on the characterization of polymeric micelle-forming tuberculostatic prodrugs and the antimycobacterial activity of these prodrugs.Method: By the condensation of hydroxymethylpyrazinamide, isoniazid and rifampin with free carboxyl groups on the copolymer poly(ethyleneglycol)-poly(aspartic acid), micelle-forming carrier-drug conjugates were obtained. These micelles were characterized by dynamic light scattering, to measure the micelle diameter; by acid-base titration, to determine the percentage of carboxylic groups occupied by the tuberculostatic; by Sudan III solubility tests, to estimate the critical micelle concentration (CMC); and visual control and spectrophotometric measurement, to determine the stability of micelles. These micelles were tested in vitro against several Mycobacterium strains.Results: As expected, the size and distribution of the micelle-forming tuberculostatic prodrugs found to be small (78.2nm, 84.2nm and 98.9 nm) while the level of the drug conjugated was high (65.02-85.7%). Furthermore, the micelles were stable in vitro, exhibiting a low level of CMC and stronger antimycobacterial activity than the original drugs.Conclusion: the results demonstrate that polymeric micelles can be used as efficient carriers for drugs, which alone, exhibit undesired pharmacokinetics, poor solubility, and low stability. The synthesized micelle-forming tuberculostatic prodrugs opens a perspective of alternative prodrugs that prolong action and decrease the toxicity of the tuberculostatic drugs of choice.

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Paracoccidioidomycosis is caused by Paracoccidioides brasiliensis, which although not formally considered an intracellular pathogen, can be internalized by epithelial cells in vitro and in vivo. The mechanisms used by P. brasiliensis to adhere to and invade non-professional phagocytes have not been identified. The signal-transduction networks, involving protein tyrosine kinase (PTK) and protein phosphatase activities, can modulate crucial events during fungal infections. In this study, the involvement of PTK has been investigated in P. brasiliensis adherence and invasion in mammalian epithelial cells. A significant inhibition of the fungal invasion occurred after the pre-treatment of the epithelial cells with genistein, a specific tyrosine kinase inhibitor, indicating that the tyrosine kinase pathway is involved in P. brasiliensis internalization. In contrast, when the fungus was treated, a slight (not significant) inhibition of PTK was observed, suggesting that PTK might not be the fungus' transduction signal pathway during the invasion process of epithelial cells. An intense PTK immunofluorescence labeling was observed in the periphery of the P. brasiliensis infected cells, little PTK labeling was found in both uninfected cells and yeast cells, at later infection times (8 and 24 h). Moreover, when the epithelial cells were treated with genistein and infected with P. brasiliensis, no labeling was observed, suggesting the importance of the PTK in the infectious process. These results suggest that PTK pathway participates in the transduction signal during the initial events of the adhesion and invasion processes of P. brasiliensis to mammalian epithelial cells.

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The aim of this study was to analyze the effects of formulations containing DMAE pidolate and DMAE acetoamidobenzoate on the skin. Four areas of five swines were submitted to following treatments during 15 days: C (Control), S (Silicone = 80 % DC*LC Blend (R)), F1 (DMAE acetoamidobenzoate), F2 (DMAE pidolate). Measures of the thickness of epidermis and stratum corneum, and the density population of fibroblasts and leukocytes in papillary dermis were obtained. We also assessed possible variations in birefringence of dermis collagen bundles. Means of the data was compared using ANOVA followed by the Tukey test. The F1 and F2 groups showed a thicker epidermis than the control group (p < 0.01), but did not demonstrate a significant difference in the number of fibroblasts and leukocytes, as well as in the birefringent areas of collagen bundles, in comparison with the control groups. The DMAE-supplemented formulations enhanced viable epidermis thickness, but did not modify structures related with mechanical properties of the skin.

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Objective: To evaluate the acute effects of static stretching before and after isokinetic exercise, neuromuscular and biomechanical properties of muscles Biceps Femoris (BF) and semitendinosus (ST). Methods: Eighty-nine volunteers of both genders, healthy and physically active, with a mean age of 22.52 ± 2.6 years and mean BMI 23.86 ± 3.2 kg/m² were randomized into 4 groups: Control Group (CG) made only one Protocol Exercise (PE) without performing the stretching, the Experimental Group 1 (EG1) did stretching before PE; EG2 did the stretching after PE and EG3 did stretching before and after PE. The volunteers were evaluated on the following variables: Range of motion (ROM), soreness, dynamometric variables concentric and eccentric, Neuromuscular Latency Time (NLT) and electromyographic. In the data analysis was assigned a significance level of 5%. Results: ADM and TLNM reported significant reduction in CG, but remained unchanged in GE with p<0,05 and p<0,01, respectively. As for the soreness, no differences between the groups. The electromyographic activity of the BF and ST, in the concentric phase, showed a significant decrease in all groups (p<0,01). However, in the eccentric phase, ST revealed reduction in all groups (p <0.01), except for the CG, while the BF remained unchanged in all groups. The PT showed significant reduction in both conditions (concentric and eccentric) for all groups, with no difference between them (p<0,01). Conclusion: The results of this study do not favor the use of static stretching, even of short duration, before physical activity. However, after exercise or at times unrelated to the sport, he should be given with the aim of avoiding muscle shortening

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The mechanical properties of metals with a body-centered cubic (bcc) structure, such as Nb, Ta, V, and their alloys, are modified with the introduction of interstitial impurities, such as O, N, C, or H. These metals can dissolve great amounts of O and N, for example, to form solid solutions. The interstitial solute atoms (ISA) in metals with a bcc structure occupy octahedral sites and cause local distortion with tetragonal symmetry. So ISA in these metals forms an elastic dipole that can align along one of the three cubic axis of the crystal. In the present paper, the torsion pendulum technique was employed for the investigation of various interactions among the metallic matrix and different interstitial solutes in the Nb-46wt%Ti alloy. From the relaxation spectra, we obtained the diffusion coefficients, pre-exponential factors, and activation energies for nitrogen in the Nb-46wt%Ti alloy.

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Several works characterize the presence of spinner dolphins at Fernando de Noronha Archipelago in the Dolphins Bay. Though, the dolphins abidance inside this cove has decreased and a new area has been occupied by the animals to achieve the same behaviors, that are resting, breeding and nursing. This area comprises the Inside Sea northeast border of Fernando s de Noronha Island, including the opposing Middle and Dog shore area, the San Antonio Bay and the Between Islands region. The aim was to characterize the dolphins occupation and describe their interactions with the tourism in this area. Data were collected in 2008 and 2009 through a fixed point observation. The study area was divided into seven sub-areas, recording: presence/absence of dolphins, days abidance endurance, abidance length in each area, estimated number of individuals, dolphins direction and speed of displacement, boats presence, interaction period, monitoring, boats attitude and velocity. The dolphins abidance time displayed the same pattern during both years of study, with the higher occupancy in the Between Islands region. Groups with farther than 200 individuals were more frequent both 2008 (46.2%) and 2009 (42.3%). Thus the displacement s slow speed as the preferred direction towards Rat Island also showed the same pattern in both years. The Between Islands region also presented the boats major abidance near the dolphins groups. Boats moved farther in slow speed (95%) than at high speed (5%). The legislation s compliance for the cetaceans protection occurred in 89.7% of 2.839 interactions between boats and spinners, in which this variable was recorded. Whenever boats moved at a slow speed during the meetings with spinner dolphins groups, animals also moved at a slow speed (n = 337), significantly more than the fast displacements (n = 128) ix or "porpoise" (n = 4) (X2 = 318.543, p = -0.001). When boats quickly passed by groups, a significant difference between the dolphins displacement speeds was observed (X2 = 18.264, p =- 0.001), however, the slow (47%) and fast (47% ) displacements frequency was equal, noted the difference with the porpoise displacements (6%), which had the lowest frequency. Data indicate the establishment of a new occupation pattern of the spinner dolphins at Fernando de Noronha, with the Between Islands area being of great importance to the dolphins habits and currently the main area of the boats meeting with the dolphins, showing the need of new conservation measures in this area

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JUSTIFICATIVA E OBJETIVOS: O uso espinhal de opióides pode causar alguns efeitos indesejáveis, dentre os quais, o mais freqüente é o prurido que, apesar de sua baixa morbidade, pode proporcionar desconforto intenso ao paciente e prolongar o período de internação. O objetivo deste estudo foi avaliar diversas opções terapêuticas no tratamento profilático do prurido após administração de sufentanil por via subaracnóidea. MÉTODO: Foram distribuídos de maneira aleatória, por sorteio, 100 pacientes a serem submetidos à intervenção cirúrgica não-obstétricas em cinco grupos, de acordo com o tratamento utilizado: controle (ausência de tratamento - C); droperidol 2,5 mg (D); nalbufina 10 mg (N); associação dos medicamentos anteriores (DN) e ondansetron 8 mg (O). O prurido foi avaliado quantitativamente 30 minutos, 1, 2, e 3 horas após a administração subaracnóidea de sufentanil. RESULTADOS: Os grupos C e O apresentaram incidência significativamente maior de prurido em relação aos grupos D, N e DN. Entretanto, não houve diferença significativa na necessidade de tratamento específico com naloxona entre os grupos tratados. CONCLUSÕES: O tratamento profilático do prurido neste estudo, independentemente do fármaco utilizado, diminuiu sua intensidade e limitou a necessidade de tratamento específico com naloxona.

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OBJETIVO: em virtude do aumento progressivo da utilização de bebidas gaseificadas e do ganho de peso na população brasileira, e sabendo-se que os refrigerantes têm no gás carbônico um fator em comum, planejou-se um estudo experimental em ratos para investigar os efeitos da água gaseificada na ingestão hídrica e alimentar, ganho de peso, área gástrica, glicemia, hematócrito e hemoglobina. MÉTODOS: Foram constituídos 4 grupos de 12 ratos acompanhados por 36 dias. Ao Grupo-1 foi oferecido 35 g/dia de ração ad libitum e 20 ml de água não gaseificada em 4 períodos diários, ao Grupo-2 foi oferecido 35 g/dia de ração ad libitum e 20 ml de água gaseificada em 4 períodos diários, ao Grupo-3 foi oferecido 10 g/dia de ração ad libitum e 20 ml de água não gaseificada em 4 períodos diários e ao Grupo-4 foi oferecido 10 g/dia de ração ad libitum e 20 ml de água gaseificada em 4 períodos diários. RESULTADOS: Os resultados identificaram que os animais que foram submetidos ao tratamento com água gaseificada (Grupo-2 e Grupo-4), apresentaram um maior volume de ingestão hídrica e aumento significativo da área gástrica (p<0,001), no Grupo-2 a ingestão alimentar assim como o ganho de peso foi significativo (p<0,01), os dados de glicemia, hematócrito e hemoglobina não tiveram alterações significativas entre os grupos estudados. CONCLUSÃO: Nas condições em que foi realizado este experimento, concluímos que a água gaseificada favoreceu a ingestão hídrica e alimentar, o ganho de peso e o aumento da área gástrica.