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Liquid-liquid extraction of proteases from fermented broth by PEG/citrate aqueous two-phase system

PORTO, T. S.; SILVA, G. M. Medeiros e; PORTO, C. S.; CAVALCANTI, M. T. H.; BARROS NETO, Benicio; LIMA-FILHO, J. L.; CONVERTI, A.; PORTO, A. L. F.; PESSOA JR., A.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37%
This work deals with the use of an aqueous two-phase system (ATPS) of PEG/citrate to remove proteases from a Clostridium perfringens fermentation broth. To plan the experimental tests and evaluate the corresponding results, three successive experimental designs were employed, for which the PEG molar mass (M-PEG) and concentration (C-PEG), the citrate concentration (C-C) and the pH were selected as independent variables, while the purification factor (PF), the partition coefficient (K), the activity yield (Y) and the selectivity (S) were selected as responses. PF of proteases in the top phase was shown to increase with increasing MPEG and decreasing Cc, whereas a completely opposite trend was observed for K. On the other hand, Y was favored by simultaneous decreases in both these variables, while S decreased with increasing Cc. Therefore, selecting a simultaneous increase in PF and Y as the most desirable result, the best performance of the system was obtained using M-PEG = 10-000 g/mol C-PEG = 22% (w/w) and C-c = 8.0% (w/w) at pH 8.5. Under these conditions, the activity yield was very high (131 %) but the purification factor (4.2) and the selectivity (4.3) were lower than those ensured by more selective purification methods. According to these results...

Dissolution Enhancement and Characterization of Nimodipine Solid Dispersions with Poloxamer 407 or PEG 6000

Kreidel, R. N.; Duque, M. D.; Serra, C. H. R.; Velasco, M. V. R.; Baby, A. R.; Kaneko, T. M.; Consiglieri, V. O.
Fonte: TAYLOR & FRANCIS INC; PHILADELPHIA Publicador: TAYLOR & FRANCIS INC; PHILADELPHIA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.76%
The solid dispersion approach is an alternative to increase drug solubility. Many carriers have been studied, but there is few information about poloxamer 407 (P407). Consequently, the objective of this study was to evaluate P407 as a carrier for nimodipine solid dispersions and to compare its solubility and dissolution rates with those from polyethylene glycol (PEG 6000). The solid dispersions were prepared by the hot melting and solvent methods and they were characterized by FTIR, DSC, solubility, and dissolution tests. The results indicated a three-fold increase in solid dispersions solubility in the presence with P407 than those prepared with PEG.

Desenvolvimento de nanopartículas de PLA e PLA-PEG para administração intranasal de zidovudina

Mainardes, Rubiana Mara
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: 133 f.
POR
Relevância na Pesquisa
37.13%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Pós-graduação em Ciências Farmacêuticas - FCFAR; A zidovudina (AZT) é um fármaco amplamente usado no tratamento da síndrome da imunodeficiência adquirida. O AZT apresenta baixa biodisponibilidade oral pois sofre rápido e extenso metabolismo de primeira passagem hepática, além de curto t1/2. Sendo assim, altas e freqüentes doses são requeridas para se manter concentrações plasmáticas efetivas e, dessa maneira, apresenta graves efeitos colaterais, dose-dependentes, que limitam o seu uso em determinados tipos de pacientes. As nanopartículas são eficientes sistemas poliméricos que contribuem para a redução da toxicidade de fármacos, pois são capazes de liberá-los de maneira prolongada, proporcionando maior tempo de contato do fármaco com o plasma e tecidos. A via de administração intranasal é uma rota interessante, quando se deseja evitar o metabolismo de primeira passagem e, também, pode oferecer um ótimo perfil de absorção para nanopartículas. Neste trabalho, estudouse a incorporação de AZT em nanopartículas de PLA e de blendas de PLA-PEG com diferentes razões molares. A caracterização físico-química demonstrou que a presença do PEG influenciou a forma...

Preparation and characterization of PEG-coated silica nanoparticles for oral insulin delivery

Andreani, Tatiana; Souza, Ana Luiza R. de; Kiill, Charlene P.; Lorenzon, Esteban N.; Fangueiro, Joana F.; Cristina Calpena, Ana; Chaud, Marco V.; Garcia, Maria L.; Gremiao, Maria Palmira D.; Silva, Amelia M.; Souto, Eliana B.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 627-635
ENG
Relevância na Pesquisa
37.11%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 12/10174-3; The present study reports the production and characterization of PEG-coated silica nanoparticles (SiNP-PEG) containing insulin for oral administration. High (PEG 20,000) and low (PEG 6000) PEG molecular weights were used in the preparations. SiNP were produced by sol gel technology followed by PEG adsorption and characterized for in vitro release by Franz diffusion cells. In vitro permeation profile was assessed using everted rat intestine. HPLC method has been validated for the determination of insulin released and permeated. Insulin secondary structure was performed by circular dichroism (CD). Uncoated SiNP allowed slower insulin release in comparison to SiNP PEG. The coating with high molecular weight PEG did not significantly (p>0.05) alter insulin release. The slow insulin release is attributed to the affinity of insulin for silanol groups at silica surface. Drug release followed second order kinetics for uncoated and SiNP PEG at pH 2.0. On the other hand, at pH 6.8, the best fitting was first-order for SiNP PEG, except for SiNP which showed a Boltzmann behavior. Comparing the values of half-live, SiNP PEG 20,000 showed a faster diffusion followed by Si-PEG 6000 and SiNP. CD studies showed no conformational changes occurring after protein release from the nanoparticles under gastrointestinal simulated conditions. (C) 2014 Elsevier B.V. All rights reserved.

Extraction of fibrinolytic proteases from Streptomyces sp. DPUA1576 using PEG-phosphate aqueous two-phase systems

Silva, Germana Michelle de Medeiros e; Marques, Daniela Araújo Viana; Porto, Tatiana Souza; Lima Filho, José L.; Teixeira, J. A.; Pessoa Júnior, Adalberto; Porto, Ana L. F.
Fonte: Elsevier; Elsevier BV Publicador: Elsevier; Elsevier BV
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
37%
Extraction of fibrinolytic protease from Streptomyces sp. DPUA1576 fermentation broth was performed using polyethylene glycol (PEG) – phosphate salts aqueous two phase system (ATPS). The influence of pH, PEG molar mass, PEG and phosphate concentrations on fibrinolytic protease partition coefficient (K) were evaluated by 24 full factorial design. Fibrinolytic protease partitioned preferentially to the (PEG)-rich phase with the highest partition coefficient (K = 37.00) obtained in the system 20% (w/w) PEG 1500 (g/mol)-14% (w/w) phosphate at pH 8.0. The system that allowed for the highest extraction consisted of 15% (w/w) PEG 3350-12% (w/w) phosphate, at pH 7.0. In these conditions, a purification factor of 1.51 was obtained for a partition coefficient of 6.41 with the fibrinolytic activity (FA) retained in the top phase. Obtained results confirm the interest of considering ATPS as an alternative extraction method for fibrinolytic protease from Streptomyces sp. DPUA1576.

Stability of clavulanic acid in PEG/citrate and liquid–liquid extraction in aqueous two-phase system

Carneiro-da-Cunha, M. N.; Souza, K. P. S.; Mota, A.; Teixeira, J. A.; Porto, C. S.; Porto, Tatiana Souza; Porto, Ana L. F.
Fonte: Elsevier BV Publicador: Elsevier BV
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
36.96%
β-Lactamases are enzymes responsible for the hydrolysis of β-lactam antibiotics, being produced by several pathogenic bacteria. Clavulanic acid is a commercially and clinically important β-lactamase inhibitor, its extraction being possible by the application of aqueous two-phase system. In this study, clavulanic acid stability was investigated at different molar mass PEG (400, 1 000 and 20 000 g mol−1) and at different citrate concentrations (5 and 20%) PEG/citrate aqueous-two phase systems (ATPS), under different pH values (4.0–8.0). Clavulanic acid extraction was also evaluated. Low citrate concentration and PEG 20 000 (g mol−1) ATPS, at pH 6.0, were shown to be the systems that presented the highest clavulanic acid stability. Based on this, a factorial design 22 was used to evaluate CA extraction, being PEG (20, 25 and 30%) and citrate (5, 10 and 15%) concentrations the parameters evaluated. Clavulanic acid was extracted into the PEG-rich phase (133.66 mg L−1), the highest values of the partition coefficient and yield being K = 5.92, Y = 103.53%, respectively The ATPS was not only effective on clavulanic acid extraction, but also its degradation was minimal. These results clearly indicate that ATPS can be successfully applied as a first step for the purification of clavulanic acid.

Cation effect on the (PEG 8000 + sodium sulfate) and (PEG 8000 + magnesium sulfate) aqueous two-phase system: Relative hydrophobicity of the equilibrium phases

Wysoczanska, Kamila; Silvério, Sara C.; Teixeira, J. A.; Macedo, Eugénia A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /12/2015 ENG
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The partitioning of four dinitrophenylated (DNP-) amino acids in aqueous two-phase systems of polyethylene glycol (PEG)-8000sodium sulfate and polyethylene glycol (PEG)-8000magnesium sulfate in five different tie-lines was experimentally determined at 298.15 K. The Gibbs free energy of transfer of a methylene group between the two phases was calculated from the measured partition coefficients. This characterizes the relative hydrophobicity of the equilibrium phases. Values of G(CH2) were in range from (-0.674 to -1.012) kJ·mol-1. A comparison of both systems was carried out. The results show that the cation type has a strong influence on the amino acids partitioning process. The largest relative hydrophobicity was noted for the ATPS system formed by sodium sulfate. This showed to be a better system for the separation.; FCT/MEC and FEDER under Programe PT2020 (Project UID/EQU/50020/2013), and co-financed by QREN, ON2 and FEDER (Projects NORTE-07-0162-FEDER-000050 and NORTE-07-0124-FEDER-0000011)

Influence of poly(ethylene grycol) - (PEG) on the properties of influence of poly(3-hydroxybutyrate-CO-3-hydroxyvalerate) - PHBV

Catoni,Sara E. M.; Trindade,Ketlyn N.; Gomes,Caio A. T.; Schneider,Andréa L. S.; Pezzin,Ana P.T.; Soldi,Valdir
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
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Films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) - PHBV with polyethylene glycol (PEG) were prepared by casting solvent evaporation. The thermal behavior, morphology, crystallinity and molecular weight of these films were studied by the following techniques: differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), size exclusion chromatography (SEC). Mixtures of PHBV/PEG showed a high crystallinity degree, measured by XRD, with values ranging between 60 and 90% according to the concentration of PEG. The melting temperature of PHBV decreased with increasing addition of plasticizer (PEG) in the mixture. SEM results showed that the mixtures were uniform, except for the composition 50/50 which proved to be heterogeneous, as evidenced by the presence of two phases. PHBV had molar mass (Mw = 206000 g mol-1), while the introduced PEG molar mass (Mw = 1350 to 1650 g mol-1). The addition of PEG caused the crystallinity of the polymer films to increase owing to the high crystallinity of PEG. The melting point of the PHBV/PEG mixtures also diminished. In addition, SEC analysis of the blends indicated a reduced molar mass for the mixtures in comparison to pure PHBV (100/0).

Partitioning optimization of proteins from Zea mays malt in ATPS PEG 6000/CaCl2

Ferreira,Graziela Batista; Evangelista,Alex Ferreira; Severo Junior,João Baptista; Souza,Roberto Rodrigues de; Santana,José Carlos Curvelo; Tambourgi,Elias Basile; Jordão,Elizabete
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2007 EN
Relevância na Pesquisa
36.85%
This work aimed to establish the relationship between the compositions and pH of ATPS PEG 6000/CaCl2 and the proteins partition from maize malt and also to simplify the process optimization in ATPS for a statistical model, established by response surface methodology (RSM). Results showed that these were no influence of pH on the phase diagrams and on the composition of tie line length of PEG 6000/CaCl2 ATPS. SRM analyses showed that elevated pH and larger tie line length were the best conditions for recovering of maize malt proteins. The maximum partition coefficient by PEG 6000/CaCl2 ATPS was about 4.2 and was achieved in ATPS in a single purification step. The theoretical maximum partition coefficient was between 4.1-4.3. The process was very suitable for continuous aqueous two-phase purification due to the stability of proteins (e.g. and -amylases) and could increase their content into middle.

Purificação parcial de colagenase produzida por Penicillium aurantiogriseum URM4622 utilizando sistema de duas fases aquosas PEG-fosfato

Ubertino Rosso, Bruno; das Graças Carneiro da Cunha, Maria (Orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
PT_BR
Relevância na Pesquisa
36.96%
As colagenases são enzimas, obtidas a partir de procariotos e eucariotos, que clivam a cadeia protéica do colágeno em pH e temperatura fisiológicos. Estas enzimas são empregadas em diversas aplicações industriais com destaque para a indústria farmacêutica, onde são aplicadas no tratamento médico de feridas, cicatrizes e queimaduras. A proposta para a utilização do sistema de duas fases aquosas (SDFA) é devido à alta relação custo-benefício, baixa tensão interfacial, fácil escalonamento e a sua capacidade de purificar uma proteína em um ambiente rico em água (80-90%), o que favorece a estrutura protéica e retém assim a sua atividade biológica após purificação. Este trabalho visa à purificação de colagenase produzida por Penicillium aurantiogriseum (URM-4622) utilizando SDFA PEG/fosfato. O planejamento experimental (23) foi usado para selecionar as variáveis significativas no processo de purificação, e a massa molar do PEG (MMPEG), concentração do PEG (CPEG) e concentração do fosfato (CFOS) foram as variáveis estudadas. O sistema de duas fases aquosas foi composto de PEG 550, 1500 e 4000 g/mol nas concentrações de 15, 17,5 e 20% (m/m) e concentrações de fosfato de 12,5, 15 e 17...

Obtenção e Caracterização Físico-Química do Sistema Compósito PEG-TiO2

Maria, Roberta Patrícia Medeiros de
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Química; Físico-Química; Química Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Química; Físico-Química; Química
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
37.05%
Hybrid systems formed from polymers and transition metals have now their physical and chemical properties extensively investigated for use in electronic devices. In this work, Titanium Dioxide (TiO2) from the precursor of titanium tetrabutoxide and the composite system Poly(Ethylene Glycol)-Titanium Dioxide (TiO2-PEG) were synthesized by sol-gel method. The PEG as acquired and TiO2 and composites powders were analyzed by X-Ray Diffraction (XRD), Spectroscopy in the Infrared region with Fourier transform (IRFT), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). In the XRD analysis were observed in the TiO2 crystal faces of one of its polymorphs - anatase phase, crystal planes in Poly (Ethylene Glycol) with considerable intensity and in the composite systems the mixture of crystal faces of their precursors isolated and reduction of crystallinity. The TG / DTG suggested increasing the thermal instability of PEG in the composite powders as TiO2 is incorporated into the system. Spectral analysis presented in the infrared overlapping bands for the polymer and metal oxide, reducing the intensity of symmetric stretching of ligand groups in the main chain polymer and angular deformations; were observed using SEM micrographs of the morphological changes suffered by composite systems with the variation of the oxide concentration. Analyses by impedance spectroscopy indicated that the increased conductivity in composite occurs in line with the addition of the metal oxide concentration in the composite system; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; Sistemas híbridos formados a partir de polímeros e metais de transição atualmente têm suas propriedades físicas e químicas extensivamente investigadas para aplicação em dispositivos eletrônicos. Neste trabalho...

Does a formal common-basket peg in East Asia make economic sense?

de Brouwer, Gordon
Fonte: Routledge, London Publicador: Routledge, London
Tipo: Parte de Livro Formato: 1352256 bytes; 353 bytes; application/pdf; application/octet-stream
EN_AU
Relevância na Pesquisa
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Before the financial crisis, a number of east Asian economies managed their exchange rates with the aim of stabilising the value of their currency against a basket of key major currencies, but overwhelmingly the US dollar (Frankel and Wei 1994). This suited these economies in the first half of the 1990s as the yen appreciated against the dollar, diverting trade and investment their way and stimulating economic growth. But as the dollar appreciated against the yen from 1995, these countries lost competitiveness relative to Japan and Europe, and their trading positions deteriorated, leaving them vulnerable to changes in investor sentiment. This experience has been taken to show the folly of a country tying its currency to that of only one of its several major trading partners: so long as the major currencies move by large amounts against each other, a country which exports to all the major economies but targets stability only in its exchange rate with one major currency will experience variability in its effective exchange rate and its bilateral exchange rates with the other major currencies. At the same time, trade within east Asia has become steadily more important to countries in the region. To the degree that the weights in an effective exchange rate target differ between countries...

Utilização de sistemas poliméricos de duas fases aquosas (SPDFA) compostos por polietileno glicol/ácido poliacrílico (PEG/APA) para extração de ácido clavulânico; Utilization of aqueous two phase systems (ATPS) composed of polyethylene glycol/polyacrylic acid (PEG/APA) in the extraction of clavulanic acid.

Rosso, Bruno Ubertino
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/09/2013 PT
Relevância na Pesquisa
37.1%
A viabilidade da produção em escala industrial de produtos biotecnológicos de interesse comercial e terapêutico, como os fármacos, depende significativamente das técnicas de separação e purificação utilizadas. A aplicação do sistema de duas fases aquosas (SDFA) é proposta como alternativa para a purificação, pois permite a separação e análise de biomoléculas, de modo que estas não percam sua atividade ou propriedades desejadas. Esta técnica é interessante para a purificação em larga escala, pois permite partição seletiva, com potencial de obtenção de altos rendimentos, além de apresentar boa relação custo-benefício. O presente trabalho estudou a purificação por extração líquido-líquido do ácido clavulânico em SDFA utilizando um novo sistema polimérico aquoso, formado pelos polímeros polietileno glicol (PEG) e ácido poliacrílico (APA). Foram estudadas diferentes composições do sistema polimérico aquoso PEG/APA, empregando diferentes massas molares e concentrações para o PEG e utilizando a massa molar 8000g/mol para o APA. Com base nas informações obtidas o melhor ponto de extração para o ácido clavulânico na presença de Na2SO4 foi definido como MPEG=400 g/mol, CPEG=17,5% (m/m) e CNaPA=22...

Geopolymer/PEG Hybrid Materials Synthesis and Investigation of the Polymer Influence on Microstructure and Mechanical Behavior

Catauro,Michelina; Papale,Ferdinando; Lamanna,Giuseppe; Bollino,Flavia
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2015 EN
Relevância na Pesquisa
36.85%
Geopolymers are aluminosilicate inorganic polymers, obtained from the alkali activation of powders containing SiO2+Al2O3>80wt%, mainly proposed as environmentally friendly building materials. In this work, metakaolin-based geopolymers have been prepared and a water-soluble polymer, polyethylene glycol (PEG), has been added in different percentages to obtain organic-inorganic hybrid geopolymers. The influence of both the polymer amount and aging time on the structure and the mechanical behavior of the materials were investigated. FTIR spectroscopy allowed us to follow the evolution of the aluminosilicate framework during the geopolymerization process. This analysis revealed that PEG leads to a network which is rich in Al-O-Si bonds and forms H-bonds with the inorganic phase. SEM microscope showed that the two phases are interpenetrated on micrometric scales. Traction and bending tests have been carried out on appropriate samples to investigate the mechanical behavior of the obtained hybrids, showing that both PEG content and aging time affect the material behavior.

"Extração da pró-toxina épsilon e de uma protease a partir de ´Clostridium perfringens´ em sistemas de duas fases aquosas utilizando PEG/citrato" ; Extraction of epsilon prototoxin and protease from Clostridium perfringens by aqueous two-phase systems using PEG/Citrate

Porto, Tatiana Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/08/2004 PT
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Este trabalho tem como finalidade obter condições de recuperar e purificar a pró-toxina épsilon e uma protease produzida pelo Clostridium perfringens através do uso da técnica de extração líquido-líquido em sistema de duas fases aquosas (SDFA) para utilização na produção de vacinas. A aplicação do sistema de duas fases aquosas é proposta como alternativa para a purificação, pois permite a separação e análise de partículas biológicas. Esta técnica é aconselhável para purificação em larga escala pela possibilidade de partição seletiva com altos rendimentos, além de apresentar uma boa relação custo-benefício. Foram construídas as curvas binodais que foram utilizadas para análise da composição dos sistemas de duas fases aquosas formados por polietileno glicol e citrato de sódio, como também a extração e recuperação da pró-toxina épsilon e da protease produzidas por Clostridium perfringens. As curvas binodais foram construídas utilizando PEG 400, 550, 1000, 1500, 3350 e 8000 em diferentes valores de pH (6,0; 6,5; 7,0; 7,5 e 8,0) e água para formação do sistema. Também foram construídas curvas na presença de caldo clarificado em substituição à água. Foi avaliada ainda a estabilidade da pró-toxina épsilon...

Nanopartículas de PLA e PLA-PEG contendo tamoxifeno: preparação, caracterização e avaliação in vitro e in vivo; PLA and PLA-PEG nanoparticles containing tamoxifeno: preparation, characterization and in vitro and in vivo evaluation

Oliveira, Samantha Sant'Anna Marotta de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/07/2014 PT
Relevância na Pesquisa
37.15%
O câncer de mama constitui o segundo tipo de câncer mais frequente no mundo e o mais comum entre as mulheres, representando uma das principais causas de morte. O tamoxifeno é um fármaco antiestrogênico utilizado para o tratamento deste tipo de câncer desde 1971 e ainda é o mais utilizado nos casos de tumores mamários que expressam receptores de estrógeno. Apesar de apresentar resultados significativamente positivos, seu efeito antiestrogênico não se restringe apenas ao sítio tumoral causando, com isso, efeitos colaterais graves que podem deixar sequelas. A proposta deste trabalho foi desenvolver sistemas de liberação nanoparticulados à base de PLA e PLA-PEG para veiculação do tamoxifeno, como uma estratégia para o potencial aumento da segurança e da eficácia deste fármaco através de um possível direcionamento passivo ao sítio de ação, devido à permeabilidade vascular aumentada destas regiões tumorais. As nanopartículas foram preparadas pela técnica de nanoprecipitação e apresentaram diâmetro médio inferior a 200 nm para a maioria das formulações. Foram avaliados três estabilizantes, o poloxamer 407, o poloxamer 188 e o polissorbato 80, este último proporcionou maior eficiência de encapsulação...

The effect of polyethyllene gyicol (Peg) on protein output of free range Alentejano pigs

Ferraz de Oliveira, M.I.; Cancela de´Abreu, M.; Freitas, A.
Fonte: Proceedings of the 6th International Symposium on the Mediterranean Pig. Publicador: Proceedings of the 6th International Symposium on the Mediterranean Pig.
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
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The effect of PEG treated or untreated acorns fed to Alentejano pigs, on the protein output of the animals were studied. The animals had access to two sown pasture fields based on Trifolium incarnatum and Lolium westerwoldicum. Four dietary treatments were tested with 5 pigs per treatment in a two by two factorial experimental design (factor 1: sown species; factor 2: acorn with or without PEG). Intake of acorns and protein faecal concentration were measured individually. Faecal output was estimated using an external faecal marker (dotriacontane, C32). Crude protein faecal concentration of animals fed acorns treated with PEG was significantly lower (P<0,05) then those fed untreated acorns, suggesting that the PEG may have increased the availability of dietary protein to the animals. However, the estimation of protein faecal output using the n-alkane C32 was not significantly affected by the PEG treatment, even though, for the animals in the Lolium westerwoldicum pasture, there was a decrease (P=0,063) in the total excretion of CP when acorns were treated with PEG.

Volumetric properties of (PEG 400 + water) and (PEG 400 + ethanol) mixtures at several temperatures and correlation with the Jouyban-Acree model

Rodríguez,Gerson A.; Holguín,Andrés R.; Martínez,Fleming; Khoubnasabjafari,Maryam; Jouyban,Abolghasem
Fonte: Revista Colombiana de Ciencias Químico - Farmacéuticas Publicador: Revista Colombiana de Ciencias Químico - Farmacéuticas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
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Molar volumes and excess molar volumes were investigated from density values for (PEG 400 + water) and (PEG 400 + ethanol) binary mixtures at temperatures from 283.15 K to 313.15 K. Both systems exhibit negative excess volumes probably due to increased interactions like hydrogen bonding and/or large differences in molar volumes of components. Volume thermal expansion coefficients were also calculated for binary mixtures and pure solvents. The Jouyban-Acree model was used for density and molar volume correlations of the studied mixtures at different temperatures. The mean relative deviations between experimental and calculated density data were 0.1 and 0.5 %, for aqueous and ethanolic mixtures, respectively; whereas, in molar volume data the values were 18.0 and 6.9 %, for aqueous and ethanolic mixtures, respectively. The trained versions of the model for PEG 400 binary solvents could be used to predict the density values of other PEGs with reasonable prediction error employing the density of mono-solvents.

Preparations for colon capsule endoscopy: prospective and randomized comparative study between two preparations for colon capsule endoscopy: PEG 2 liters + ascorbic acid versus PEG 4 liters

Argüelles-Arias,Federico; San-Juan-Acosta,Mileidis; Belda,Alba; García-Montes,Josefa María; Pellicer,Francisco; Polo,Juan; Caunedo-Álvarez,Ángel; Herrerías-Gutiérrez,Juan Manuel
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/05/2014 ENG
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37.02%
Introduction: PillCam© colon capsule endoscopy (CCE) enables the study of colonic diseases in a safe and non-invasive way, although there are aspects that need to be improved. Current methods of bowel preparation lead to discordant rates of adequate cleansing and CCE excretion. Aims: To compare the efficacy of colon cleansing using two different regimes (2L PEG plus ascorbic acid versus 4L PEG alone) for PillCam Colon (C2) capsule endoscopy. Methods: Fifty eight patients included in this prospective study and randomized to: Group A, PEG plus ascorbic acid regimen (n = 28, 12 F/16 M) or group B, PEG alone regimen (n = 30, 14 F/16 M). The degree of cleansing was categorized into "excellent-good" or "fair-poor", according to Leighton's recently published preparation scale. CCE excretion rate and colon cleansing were assessed. Patients underwent to PillCam colon of second generation (C2). Results: Cleansing was considered to be excellent-good in 78 % of cases in group A and in 64 % of cases in group B, with no significant difference between the groups (p = 0.252). Nevertheless, when the grade of cleansing was analyzed in segments, a significant difference was found in the cecum and transverse colon. No differences were observed in the bubble effect between preparations. The excretion rate was 93 % in group A versus 70 % in group B (p = 0.043). Conclusions: These results suggest that a 2L PEG plus ascorbic acid regimen is at least as effective as a 4L PEG regimen. This regimen may be considered an effective alternative which would improve compliance because a smaller volume is required.

Risk of bleeding in patients undergoing percutaneous endoscopic gastrotrostomy (PEG) tube insertion under antiplatelet therapy: a systematic review with a meta-analysis

Lucendo,Alfredo J.; Sánchez-Casanueva,Tomás; Redondo,Olga; Tenias,José M.; Arias,Ángel
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/03/2015 ENG
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Background and aim: Patients undergoing percutaneous endoscopic gastrostomy (PEG) tube placement often are under antiplatelet therapy with a potential thromboembolic risk if these medications are discontinued. This systematic review aims to assess if maintaining aspirin and/or clopidogrel treatment increases the risk of bleeding following PEG placement. Methods: A systematic search of the MEDLINE, EMBASE, and SCOPUS databases was developed for studies investigating the risk of bleeding in patients on antiplatelet therapy undergoing PEG tube insertion. Summary estimates, including 95 % confidence intervals (CI), were calculated. A fixed or random effects model was used depending on heterogeneity (I²). Publication bias risks were assessed by means of funnel plot analysis. Results: Eleven studies with a total of 6,233 patients (among whom 3,665 were undergoing antiplatelet treatment), met the inclusion criteria and were included in the quantitative summary. Any PEG tube placement-related bleeding was found in 2.67 % (95 % CI 1.66 %, 3.91 %) of the entire population and in 2.7 % (95 % CI 1.5 %, 4.1 %) of patients not receiving antiplatelet therapy. Pooled relative risk (RR) for bleeding in patients under aspirin, when compared to controls...