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Med. U.P.B ; 38(2): 158-167, 17 de octubre de 2019.
Artigo em Espanhol | LILACS | ID: biblio-1023411


Los metanálisis de comparación de múltiples tratamientos permiten estudiar, a partir de revisiones sistemáticas, las comparaciones realizadas de forma directa o indirecta, sobre diversos tipos de intervenciones, con datos de varios ensayos clínicos que, por su homogeneidad en los resultados, pueden agruparse en un resultado común y expresable de manera cuantitativa. Otros nombres que recibe son: metanálisis en red, metanálisis de comparación mixta o metanálisis indirectos. Al permitir la comparación de varios tratamientos facilitan una mejor estimación del efecto de las intervenciones, lo que guía de forma más certera al clínico en sus decisiones y en la aplicación de la información en el cuidado de sus pacientes. El objetivo de esta revisión es guiar al lector para que realice de manera organizada y adecuada la lectura crítica (según recomendaciones JAMA) de los metanálisis de comparación de múltiples tratamientos. Este artículo está orientando a los autores y a los editores, y contiene información sobre cómo deben interpretarse y comunicarse estos estudios.

Multiple treatment comparison meta-analyses are systematic reviews that allow to make direct or indirect comparisons of different interventions from the data collection results of randomized clinical trials, grouping them in a common outcome or conglomerate which is expressed quantitatively. Other names given are network meta-analyses, or mixed treatment comparison meta-analyses or indirect meta-analyses. The use of the comparison of several treatments allows a greater estimation of the intervention effect. This is a guide for the physician to make more accurate decisions and to apply better care criteria to their patients. This literature review should help the reader to perform an organized and adequate critical reading (according to the JAMA recommendations) of the multiple treatment comparison meta-analyses. The article is addressed to authors and editors, and it contains information on how this type of studies should be interpreted and communicated.

Os metanálise de comparação de múltiplos tratamentos permitem estudar, a partir de revisões sistemáticas, as comparações realizadas de forma direta ou indireta, sobre diversos tipos de intervenções, com dados de vários ensaios clínicos que, por sua homogeneidade nos resultados, podem agrupar-se num resultado comum e de expressão de maneira quantitativa. Outros nomes que recebe são: metanálise em rede, metanálise de comparação mista ou metanálise indiretos. Ao permitir a comparação de vários tratamentos facilitam uma melhor estimação do efeito das intervenções, o que guia de forma mais certeira ao clínico em suas decisões e na aplicação da informação no cuidado de seus pacientes. O objetivo desta revisão é guiar ao leitor para que realize de maneira organizada e adequada a leitura crítica (segundo recomendações JAMA) dos metanálise de comparação de múltiplos tratamentos. Este artigo está orientando aos autores e aos editores, e contém informação sobre como devem interpretar-se e comunicar-se estes estudos.

Terapêutica , Metanálise como Assunto , Prática Clínica Baseada em Evidências
Biotechnol Prog ; 34(1): 206-217, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28884510


Flavonoids are important value added products for dye sensitized solar cells biosensors, functional foods, medicinal supplements, nanomaterial synthesis, and other applications. Brassica oleracea contains high levels of anthocyanins in leaf sap vacuoles, and there are many viable extraction techniques that vary in terms of simplicity, environmental impact, cost, and extract photochemical/electrochemical properties. The efficiency of value added biotechnologies from flavonoid is a function of anthocyanin activity/concentration and molecule stability (i.e., ability to retain molecular resonance under a wide range of conditions). In this paper, we show that block cryoconcentration and partial thawing of anthocyanin from B. oleracea is a green, facile, and highly efficient technique that does not require any special equipment or protocols for producing enhanced value added products. Cryoconcentration increased anthocyanin activity and total phenol content approximately 10 times compared with common extraction techniques. Cryoconcentrated extract had enhanced electrochemical properties (higher oxidation potential), improved chroma, and higher UV absorbance than extract produced with other methods for a pH range of 2-12, with minimal effect on the diffusion coefficient of the extract. As a proof of concept for energy harvesting and sensor applications, dye sensitized solar cells and pH-sensitive thin films were prepared and tested. These devices were comparable with other recently published biotechnologies in terms of efficacy, but did not require expensive/environmentally detrimental extraction or concentration methods. This low cost, biorenewable, and simple method can be used for development of a variety of value added products. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:206-217, 2018.

Antocianinas/química , Criobiologia/métodos , Flavonoides/química , Extratos Vegetais/química , Técnicas Biossensoriais , Brassica/química , Folhas de Planta/química , Energia Solar
Analyst ; 141(11): 3367-78, 2016 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-27121177


For the first time, we combine pulsed electrodeposition with out-of-phase pulsed sonication for controlled synthesis of fractal nanoplatinum structures as the transducer layer in electrochemical sensing. We develop and test this technique, called bimodal pulsed sonoelectrodeposition (pulSED), as a simple approach for creating highly conductive transducer nanometals for use in sensing and biosensing. We first compared the efficiency of pulSED nanoplatinum to other pulsed electrodeposition techniques, and then explored the effect of duty cycle and plating time on electroactive surface area and nanoparticle size/morphology. The developed pulSED nanoplatinum displayed fractal features with a relatively homogenous size distribution (26.31 ± 1.3 nm) and extremely high electroactive surface (0.28 ± 0.04 cm(2)) relative to other electroplating techniques (up to one order of magnitude higher). A high duty cycle (900 mHz) promotes formation of stable nanostructures (including fractal nanostructures) and reduces amorphous structure formation due to bubble cavitation and enhanced mass transport of metal ions to the electrode surface. To demonstrate the applicability of the pulSED technique, non-enzymatic and enzymatic sensors were developed for measuring hydrogen peroxide and glucose. The sensitivity for non-enzymatic peroxide sensing (3335 ± 305 µA cm(-2) mM(-1)), non-enzymatic glucose sensing (73 ± 14 µA cm(-2) mM(-1)) and enzymatic glucose biosensing (155 ± 25 µA cm(-2) mM(-1)) was higher than, or similar to, other nanomaterial-mediated amperometric sensors reported in the literature. The pulSED technique is a one pot method for tunable synthesis of nanometal structures as a transducer layer in electrochemical sensing and biosensing that requires no precursors or capping agents, and can be carried out at room temperature with inexpensive hardware.

Técnicas Biossensoriais , Nanoestruturas , Platina , Técnicas Eletroquímicas , Eletrodos , Fractais , Glucose/análise , Peróxido de Hidrogênio/análise
Analyst ; 140(5): 1466-76, 2015 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-25612313


Hydrogels have become increasingly popular as immobilization materials for cells, enzymes and proteins for biosensing applications. Enzymatic biosensors that utilize hydrogel as an encapsulant have shown improvements over other immobilization techniques such as cross linking and covalent bonding. However, to date there are no studies which directly compare multiple hydrogel-graphene nanocomposites using the same enzyme and test conditions. This study compares the performance of four different hydrogels used as protein encapsulants in a mediator-free biosensor based on graphene-nanometal-enzyme composites. Alcohol oxidase (AOx) was encapsulated in chitosan poly-N-isopropylacrylamide (PNIPAAM), silk fibroin or cellulose nanocrystals (CNC) hydrogels, and then spin coated onto a nanoplatinum-graphene modified electrode. The transduction mechanism for the biosensor was based on AOx-catalyzed oxidation of methanol to produce hydrogen peroxide. To isolate the effect(s) of stimulus response on biosensor behavior, all experiments were conducted at 25 °C and pH 7.10. Electroactive surface area (ESA), electrochemical impedance spectroscopy (EIS), sensitivity to methanol, response time, limit of detection, and shelf life were measured for each bionanocomposite. Chitosan and PNIPAAM had the highest sensitivity (0.46 ± 0.2 and 0.3 ± 0.1 µA mM(-1), respectively) and electroactive surface area (0.2 ± 0.06 and 0.2 ± 0.02 cm(2), respectively), as well as the fastest response time (4.3 ± 0.8 and 4.8 ± 1.1 s, respectively). Silk and CNC demonstrated lower sensitivity (0.09 ± 0.02 and 0.15 ± 0.03 µA mM(-1), respectively), lower electroactive surface area (0.12 ± 0.02 and 0.09 ± 0.03 cm(2), respectively), and longer response time (8.9 ± 2.1 and 6.3 ± 0.8 s, respectively). The high porosity of chitosan, PNIPAAM, and silk gels led to excellent transport, which was significantly better than CNC bionanocomposites. Electrochemical performance of CNC bionanocomposites were relatively poor, which may be linked to poor gel stability. The differences between the Chitosan/PNIPAAM group and the Silk/CNC group were statistically significant (p < 0.05) based on ANOVA. Each of these composites was within the range of other published devices in the literature, while some attributes were significantly improved (namely response time and shelf life). The main advantages of these hydrogel composites over other devices is that only one enzyme is required, all materials are non-toxic, the sensor does not require mediators/cofactors, and the shelf life and response time are significantly improved over other devices.

Técnicas Biossensoriais/métodos , Eletrodos , Grafite/química , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Nanocompostos/química , Nanopartículas/química , Resinas Acrílicas/química , Oxirredutases do Álcool/química , Oxirredutases do Álcool/metabolismo , Quitosana/química , Espectroscopia Dielétrica , Eletroquímica , Enzimas Imobilizadas/química , Ouro/química , Peróxido de Hidrogênio/química , Limite de Detecção , Platina/química
Biosens Bioelectron ; 58: 179-85, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24637166


Most graphene-metal nanocomposites for biosensing are formed using noble metals. Recently, development of nanocomposites using rare earth metals has gained much attention. This paper reports on the development of a nanoceria-nanoplatinum-graphene hybrid nanocomposite as a base transducing layer for mediator-free enzymatic biosensors. The hybrid nanocomposite was shown to improve detection of superoxide or hydrogen peroxide when compared to other carbon-metal hybrid nanocomposites. Based on this finding, the nanocomposite was applied for biosensing by adding either a peroxide-producing oxidase (glucose oxidase), or a superoxide-producing oxidase (xanthine oxidase). Material analysis indicated that nanoceria and nanoplatinum were equally distributed along the surface of the hybrid material, ensuring detection of either superoxide or hydrogen peroxide produced by oxidase activity. Glucose biosensors demonstrated a sensitivity (66.2±2.6µAmM(-1)cm(-2)), response time (6.3±3.4s), and limit of detection (1.3±0.6µM) that were comparable to other graphene-mediated electrodes in the current literature. Remarkably, XOD biosensor sensitivity (1164±332µAmM(-1)), response time (5.0±1.5s), and limit of detection (0.2±0.1µM) were higher than any reported biosensors using similar metal-decorated carbon nanomaterials. This material is the first demonstration of a highly efficient, diverse nanoceria/nanoplatinum/graphene hybrid nanocomposite for biosensing.

Técnicas Biossensoriais/instrumentação , Cério/química , Glucose Oxidase/química , Glucose/análise , Grafite/química , Nanocompostos/química , Platina/química , Condutometria/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Microeletrodos , Nanocompostos/ultraestrutura , Xantina/análise , Xantina Oxidase/química
Med. U.P.B ; 32(1): 30-36, ene.-jun. 2013.
Artigo em Espanhol | LILACS, COLNAL | ID: biblio-836830


Objetivo: determinar las diferencias en las variables cualitativas y cuantitativas de las características basales de los ensayos clínicos controlados con asignación aleatoria, según su tamaño de muestra. Metodología: estudio observacional, transversal que incluyó los ensayos clínicos con asignación aleatoria publicados en cuatro revistas médicas generales de alto factor de impacto. Según su tamaño de muestra, se dividieron en cinco estratos y se evaluó la diferencia entre variables cualitativas y cuantitativas de las características basales. Resultados: se analizaron 1000 variables de los pacientes que participaron en ensayos clínicos. Cuando se comparó cada uno de los grupos por tamaño de muestra con respecto al de ≥5000 pacientes, se encontró que las diferencias de medias disminuían a medida que los tamaños de muestra tenían mayor número de pacientes. Conclusiones: la diferencia de resultados de las características basales de los ensayos clínicos, es inversamente proporcional al tamaño de muestra y, por encima de 500 pacientes por grupo, las diferencias promedio serían menores al 1.2%.

Objective: To determine the differences in qualitative and quantitative variables in the baseline characteristics of the controlled clinical trials randomized by sample size. Methods: Observational, cross-sectional study including randomized clinical trials published in four high impact factor general medical journals. They were divided into five strata according to sample size; the differences between qualitative and quantitative variables of baseline characteristics were evaluated. Results: One thousand variables of patients participating in clinical trials were analyzed. By comparing each of the groups according to sample size with respect to the group of ≥ 5000 patients, it was determined that the mean differences decreased as the sample sizes included a greater number of patients. Conclusions: The differences in results of the baseline characteristics of clinical trials are inversely proportional to the sample size, and the average differences in groups above 500 patients would be less than 1.2%.

Objetivo: Determinar as diferenças nas variáveis qualitativas e quantitativas das características basais dos ensaios clínicos controlados com atribuição aleatória segundo seu tamanho de mostra. Metodologia: Estudo observacional, cross sectional que incluiu os ensaios clínicos com atribuição aleatória publicados em quatro revistas médicas generais de alto fator de impacto. Segundo o de tamanho de mostra deles, dividiram-se em cinco estratos, avaliou-se a diferença entre variáveis qualitativas e quantitativas das características basais. Resultados: Analisaram-se 1000 variáveis dos pacientes que participaram em ensaios clínicos. Ao comparar cada um dos grupos por tamanho de mostra com respeito ao de ≥5000 pacientes se encontrou que as diferenças de médias diminuíam à medida que os tamanhos de mostra tinham maior número de pacientes. Conclusões: A diferença de resultados das características basais dos ensaios clínicos, é inversamente proporcional ao tamanho de mostra e acima de 500 pacientes por grupo as diferencias média seriam menores a 1.2%.

Ensaio Clínico , Distribuição Aleatória , Tamanho da Amostra