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2.
Environ Pollut ; 243(Pt B): 1434-1449, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30278417

RESUMO

In order to clarify whether the mitochondrial dysfunction is closely related to the cell homeostasis maintenance after particulate matter (PM2.5) exposure, oxidative, inflammatory, apoptotic and mitochondrial endpoints were carefully studied in human bronchial epithelial BEAS-2B, normal human bronchial epithelial (NHBE) and chronic obstructive pulmonary disease (COPD)-diseased human bronchial epithelial (DHBE) cells acutely or repeatedly exposed to air pollution-derived PM2.5. Some modifications of the mitochondrial morphology were observed within all these cell models repeatedly exposed to the highest dose of PM2.5. Dose- and exposure-dependent oxidative damages were reported in BEAS-2B, NHBE and particularly COPD-DHBE cells acutely or repeatedly exposed to PM2.5. Nuclear factor erythroid 2-p45 related factor 2 (NRF2) gene expression and binding activity, together with the mRNA levels of some NRF2 target genes, were directly related to the number of exposures for the lowest PM2.5 dose (i.e., 2 µg/cm2), but, surprisingly, inversely related to the number of exposures for the highest dose (i.e., 10 µg/cm2). There were dose- and exposure-dependent increases of both nuclear factor kappa-B (NF-κB) binding activity and NF-κB target cytokine secretion in BEAS-2B, NHBE and particularly COPD-DHBE cells exposed to PM2.5. Mitochondrial ROS production, membrane potential depolarization, oxidative phosphorylation, and ATP production were significantly altered in all the cell models repeatedly exposed to the highest dose of PM2.5. Collectively, our results indicate a cytosolic ROS overproduction, inducing oxidative damage and activating oxygen sensitive NRF2 and NF-kB signaling pathways for all the cell models acutely or repeatedly exposed to PM2.5. However, one of the important highlight of our findings is that the prolonged and repeated exposure in BEAS-2B, NHBE and in particular sensible COPD-DHBE cells further caused an oxidative boost able to partially inactivate the NRF2 signaling pathway and to critically impair mitochondrial redox homeostasis, thereby producing a persistent mitochondrial dysfunction and a lowering cell energy supply.


Assuntos
Poluentes Atmosféricos/análise , Mitocôndrias/efeitos dos fármacos , Material Particulado/análise , Material Particulado/toxicidade , Poluentes Atmosféricos/toxicidade , Poluição do Ar/análise , Poluição do Ar/estatística & dados numéricos , Brônquios/citologia , Células Epiteliais/efeitos dos fármacos , Humanos , Hipersensibilidade , Pulmão/efeitos dos fármacos , Mitocôndrias/metabolismo , Fator 2 Relacionado a NF-E2 , Material Particulado/metabolismo , Doença Pulmonar Obstrutiva Crônica/metabolismo
3.
Chem Sci ; 8(8): 5362-5370, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28970915

RESUMO

Chemical protein synthesis gives access to well-defined native or modified proteins that are useful for studying protein structure and function. The majority of proteins synthesized up to now have been produced using native chemical ligation (NCL) in solution. Although there are significant advantages to assembling large peptides or proteins by solid phase ligation, reports of such approaches are rare. We report a novel solid phase method for protein synthesis which relies on the chemistry of the acetoacetyl group and ketoxime ligation for the attachment of the peptide to the solid support, and on a tandem transoximation/rearrangement process for the detachment of the target protein. Importantly, we show that the combination of solid phase and solution ligation techniques facilitates the production of a challenging and biologically active protein made of 180 amino acids. We show also that the solid phase method enables the purification of complex peptide segments through a chemoselective solid phase capture/release approach.

4.
Environ Pollut ; 230: 163-177, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28651088

RESUMO

Even though clinical, epidemiological and toxicological studies have progressively provided a better knowledge of the underlying mechanisms by which air pollution-derived particulate matter (PM) exerts its harmful health effects, further in vitro studies on relevant cell systems are still needed. Hence, aiming of getting closer to the human in vivo conditions, primary human bronchial epithelial cells derived from normal subjects (NHBE) or sensitive chronic obstructive pulmonary disease (COPD)-diseased patients (DHBE) were differentiated at the air-liquid interface. Thereafter, they were repeatedly exposed to air pollution-derived PM2.5 to study the occurrence of some relevant genetic and/or epigenetic endpoints. Concentration-, exposure- and season-dependent increases of OH-B[a]P metabolites in NHBE, and to a lesser extent, COPD-DHBE cells were reported; however, there were more tetra-OH-B[a]P and 8-OHdG DNA adducts in COPD-DHBE cells. No increase in primary DNA strand break nor chromosomal aberration was observed in repeatedly exposed cells. Telomere length and telomerase activity were modified in a concentration- and exposure-dependent manner in NHBE and particularly COPD-DHBE cells. There were a global DNA hypomethylation, a P16 gene promoter hypermethylation, and a decreasing DNA methyltransferase activity in NHBE and notably COPD-DHBE cells repeatedly exposed. Changes in site-specific methylation, acetylation, and phosphorylation of histone H3 (i.e., H3K4me3, H3K9ac, H3K27ac, and H3S10ph) and related enzyme activities occurred in a concentration- and exposure-dependent manner in all the repeatedly exposed cells. Collectively, these results highlighted the key role played by genetic and even epigenetic events in NHBE and particularly sensitive COPD-DHBE cells repeatedly exposed to air pollution-derived PM2.5 and their different responsiveness. While these specific epigenetic changes have been already described in COPD and even lung cancer phenotypes, our findings supported that, together with genetic events, these epigenetic events could dramatically contribute to the shift from healthy to diseased phenotypes following repeated exposure to relatively low doses of air pollution-derived PM2.5.


Assuntos
Poluentes Atmosféricos/toxicidade , Material Particulado/toxicidade , Doença Pulmonar Obstrutiva Crônica/genética , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Linhagem Celular , Epigênese Genética , Células Epiteliais/efeitos dos fármacos , Humanos , Hipersensibilidade , Material Particulado/análise , Testes de Toxicidade
6.
Environ Pollut ; 218: 1074-1088, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27593349

RESUMO

While the knowledge of the underlying mechanisms by which air pollution-derived particulate matter (PM) exerts its harmful health effects is still incomplete, detailed in vitro studies are highly needed. With the aim of getting closer to the human in vivo conditions and better integrating a number of factors related to pre-existing chronic pulmonary inflammatory, we sought to develop primary cultures of normal human bronchial epithelial (NHBE) cells and chronic obstructive pulmonary disease (COPD)-diseased human bronchial epithelial (DHBE) cells, grown at the air-liquid interface. Pan-cytokeratin and MUC5AC immunostaining confirmed the specific cell-types of both these healthy and diseased cell models and showed they are closed to human bronchial epithelia. Thereafter, healthy and diseased cells were repeatedly exposed to air pollution-derived PM4 at the non-cytotoxic concentration of 5 µg/cm2. The differences between the oxidative and inflammatory states in non-exposed NHBE and COPD-DHBE cells indicated that diseased cells conserved their specific physiopathological characteristics. Increases in both oxidative damage and cytokine secretion were reported in repeatedly exposed NHBE cells and particularly in COPD-DHBE cells. Diseased cells repeatedly exposed had lower capacities to metabolize the organic chemicals-coated onto the air-pollution-derived PM4, such as benzo[a]pyrene (B[a]P), but showed higher sensibility to the formation of OH-B[a]P DNA adducts, because their diseased state possibly affected their defenses. Differential profiles of epigenetic hallmarks (i.e., global DNA hypomethylation, P16 promoter hypermethylation, telomere length shortening, telomerase activation, and histone H3 modifications) occurred in repeatedly exposed NHBE and particularly in COPD-DHBE cells. Taken together, these results closely supported the highest responsiveness of COPD-DHBE cells to a repeated exposure to air pollution-derived PM4. The use of these innovative in vitro exposure systems such as NHBE and COPD-DHBE cells could therefore be consider as a very useful and powerful promising tool in the field of the respiratory toxicology, taking into account sensitive individuals.


Assuntos
Poluentes Atmosféricos/toxicidade , Células Epiteliais/efeitos dos fármacos , Material Particulado/toxicidade , Poluição do Ar , Linhagem Celular , Células Epiteliais/metabolismo , Humanos , Pulmão/citologia , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Doença Pulmonar Obstrutiva Crônica/metabolismo
7.
Pharm Res ; 31(3): 731-41, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24072265

RESUMO

PURPOSE: To elucidate the mass transport mechanisms controlling drug release from recently proposed, ethanol-resistant, polymeric film coatings. METHODS: Theophylline matrix pellets were coated with ethylcellulose: guar gum blends. Drug release from single pellets and ensembles of pellets was measured in various release media. Changes in the systems' morphology, composition and mechanical properties were monitored using SEM, gravimetrical analysis and a texture analyzer. Based on the obtained experimental results a mechanistically realistic mathematical model was identified and used to quantitatively predict drug release from coated pellets in ethanol-free and ethanol-containing bulk fluids. RESULTS: Drug diffusion though the intact polymeric film coatings is likely to be the dominant mass transport mechanism in the investigated systems, irrespective of the ethanol content in the surrounding environment. An appropriate solution of Fick's law could be used to quantitatively predict theophylline release from pellets coated with different ethylcellulose:guar gum blends at different coating levels. Importantly, independent experiments confirmed the theoretical predictions. CONCLUSIONS: In silico simulations can help facilitating the optimization of the novel ethanol-resistant polymeric film coatings, avoiding time-consuming and cost-intensive series of trial-and-error experiments. The presence/absence of ethanol does not affect the underlying drug release mechanisms.


Assuntos
Broncodilatadores/administração & dosagem , Celulose/análogos & derivados , Portadores de Fármacos/química , Etanol/química , Galactanos/química , Mananas/química , Gomas Vegetais/química , Teofilina/administração & dosagem , Celulose/química , Simulação por Computador , Difusão , Modelos Químicos
8.
Eur J Pharm Biopharm ; 85(3 Pt B): 1250-8, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23891769

RESUMO

Recently, ethylcellulose/guar gum blends have been reported to provide ethanol-resistant drug release kinetics from coated dosage forms. This is because the ethanol insoluble guar gum effectively avoids undesired ethylcellulose dissolution in ethanol-rich bulk fluids. However, so far the importance of crucial formulation parameters, including the minimum amount of guar gum to be incorporated and the minimum required guar gum viscosity, remains unclear. The aim of this study was to identify the most important film coating properties, determining whether or not the resulting drug release kinetics is ethanol-resistant. Theophylline matrix cores were coated in a fluid bed with blends of the aqueous ethylcellulose dispersion "Aquacoat®ECD30" and guar gum. The polymer blend ratio, guar gum viscosity, and degree of dilution of the final coating dispersion were varied. Importantly, it was found that more than 5% guar gum (referred to the total polymer content) must be incorporated in the film coating and that the apparent viscosity of a 1% aqueous guar gum solution must be greater than 150 cP to provide ethanol-resistance. In contrast, the investigated degree of coating dispersion dilution was not found to be decisive for the ethanol sensitivity. Furthermore, all investigated formulations were long term stable, even upon open storage under stress conditions for 6 months.


Assuntos
Celulose/análogos & derivados , Química Farmacêutica/métodos , Etanol/química , Galactanos/química , Mananas/química , Gomas Vegetais/química , Consumo de Bebidas Alcoólicas , Celulose/química , Preparações de Ação Retardada , Estabilidade de Medicamentos , Excipientes , Cinética , Microscopia Eletrônica de Varredura , Polímeros/química , Solubilidade , Soluções , Propriedades de Superfície , Teofilina/química , Viscosidade
9.
Rev. chil. nutr ; 40(2): 135-140, June 2013. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-687149

RESUMO

Objective: To evaluate the effectiveness of six board games to teach food and nutrition, personal hygiene and physical activity in children of elementary school education. Methods: Cluster randomized controlled study of children in basic education (7-12 year old) enrolled in the city schools from the District of Bogotá. Two local schools were selected and randomized to intervention or control group. In the intervention group were 472 children and 487 were in the control group. Children's knowledge was assessed using a questionnaire at three different times. To analyze the model we used generalized estimating equations (GEE) for repeated measures to study the effect of the intervention over time. Results: In relation to knowledge the intervention group increased its score in the second time, on a scale of 0-100 steps from 49.4 to 61.8 (p<0.001) and remained at the time. In the control group there was not a change in the score of time. Conclusions: The results suggest that the six games can be effective tools in teaching basic concepts in food, nutrition and health to schoolchildren.


Objetivo: Evaluar la efectividad de seis juegos de mesa, en la enseñanza de conceptos de alimentación y nutrición, higiene personal y práctica de actividad física en niños de educación básica. Método: Experimento clínico controlado aleatorizado por conglomerados. Se tomaron dos colegios de Bogotá, D.C. con población escolar (7-12 años) fueron seleccionaron y aleatorizados. En el grupo de intervención se incluyeron 472 niños y en el control 487. Los conocimientos de los niños se evaluaron en tres momentos diferentes. El análisis se realizó utilizando un modelo de ecuaciones de estimación generalizada (GEE) para medidas repetidas. Resultados: El grupo con intervención aumentó su puntaje en el segundo momento, sobre una escala de 0 a 100 pasó de 49.4 a 61.8 (p<0.001) y se mantuvo en el tiempo. En el grupo control no hubo cambios en el puntaje. Conclusión: Los resultados sugieren que los seis juegos de mesa pueden ser instrumentos efectivos en la enseñanza de conceptos básicos en alimentación, nutrición y salud de niños escolares.


Assuntos
Educação Alimentar e Nutricional , Criança , Ensino Fundamental e Médio , Nutrição da Criança , Jogos Recreativos , Efetividade , Colômbia
10.
J Control Release ; 169(1-2): 1-9, 2013 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-23570984

RESUMO

The sensitivity of controlled release dosage forms to the presence of ethanol in the gastro intestinal tract is critical, if the incorporated drug is potent and exhibits severe side effects. This is for instance the case for most opioid drugs. The co-ingestion of alcoholic beverages can lead to dose dumping and potentially fatal consequences. For these reasons the marketing of hydromorphone HCl extended release capsules (Palladone) was suspended. The aim of this study was to develop a novel type of controlled release film coatings, which are ethanol-resistant: even the presence of high ethanol concentrations in the surrounding bulk fluid (e.g., up to 40%) should not affect the resulting drug release kinetics. Interestingly, blends of ethylcellulose and medium or high viscosity guar gums provide such ethanol resistance. Theophylline release from pellets coated with the aqueous ethylcellulose dispersion Aquacoat® ECD 30 containing 10 or 15% medium and high viscosity guar gum was virtually unaffected by the addition of 40% ethanol to the release medium. Furthermore, drug release was shown to be long term stable from this type of dosage forms under ambient and stress conditions (without packaging material), upon appropriate curing.


Assuntos
Celulose/análogos & derivados , Preparações de Ação Retardada/metabolismo , Etanol/metabolismo , Galactanos/metabolismo , Mananas/metabolismo , Gomas Vegetais/metabolismo , Teofilina/administração & dosagem , Vasodilatadores/administração & dosagem , Celulose/química , Celulose/metabolismo , Preparações de Ação Retardada/química , Galactanos/química , Mananas/química , Gomas Vegetais/química
11.
Cancer Radiother ; 16(7): 633-7, 2012 Oct.
Artigo em Francês | MEDLINE | ID: mdl-23089068

RESUMO

The identification of patient plays a key role in the quality and safety of radiotherapy. It does impact on all professional staff and on patients. After the regulatory authority approval (Cnil), a pilot study has been performed on 1901 patients. Acceptance has been very high (>93%) with a low risk of misidentification (<0.1%). The next step will be to implement and test a bimodal system in order to improve registration capacity and sensitivity.


Assuntos
Identificação Biométrica/métodos , Institutos de Câncer/organização & administração , Dermatoglifia , Sistemas de Identificação de Pacientes/métodos , Radioterapia , Estudos de Viabilidade , França , Humanos , Aceitação pelo Paciente de Cuidados de Saúde
12.
Eur J Pharm Biopharm ; 78(3): 455-61, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21349330

RESUMO

When using aqueous polymer dispersions for the preparation of controlled-release film coatings, instability during long-term storage can be a crucial concern. Generally, a thermal after treatment is required to assure sufficient polymer particle coalescence. This curing step is often performed under static conditions in an oven, which is a time-consuming and rather cumbersome process. Dynamic curing in the fluidized bed presents an attractive alternative. However, yet little is known on the required conditions, in particular: temperature, time, and relative humidity, to provide stable film structures. The aim of this study was to better understand the importance of these key factors and to evaluate the potential of dynamic curing compared with that of static curing. Recently proposed ethylcellulose:poly(vinyl alcohol)-poly(ethylene glycol) graft copolymer (PVA-PEG graft copolymer) dispersions were coated on theophylline and metoprolol succinate-loaded starter cores, exhibiting different osmotic activity. Importantly, processing times as short as 2h were found to be sufficient to provide long-term stable films, even upon open storage under stress conditions. For instance, 2-h dynamic curing at 57°C and 15% relative humidity are assuring stable film structures in the case of theophylline matrix cores coated with 15%ethylcellulose:PVA-PEG graft copolymer 85:15. Importantly, the approach is also applicable to other types of drugs and starter cores, and the underlying drug release mechanisms remain unaltered.


Assuntos
Celulose/análogos & derivados , Composição de Medicamentos/métodos , Polímeros/química , Polivinil/química , Anti-Hipertensivos/química , Broncodilatadores/química , Celulose/química , Preparações de Ação Retardada , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Implantes de Medicamento/química , Estabilidade de Medicamentos , Excipientes/química , Metoprolol/química , Solubilidade , Sacarose/química , Suspensões , Teofilina/química
13.
J Control Release ; 135(1): 71-9, 2009 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-19136034

RESUMO

The aim of this study was to elucidate the underlying drug release mechanisms in pellets coated with aqueous ethylcellulose dispersion, providing long term stable drug release profiles and containing different types of starter cores. The systems were thoroughly characterized using mechanical analysis; the sensitivity of drug release to the osmolality of the release medium was measured; scanning electron microscopy and optical macroscopy were used to monitor the pellets' morphology and dimensions upon exposure to different media, and drug release was measured from single and ensembles of pellets as well as from thin, free films. All experimental results indicate that diltiazem HCl release from pellets coated with ethylcellulose containing small amounts of poly(vinyl alcohol)-poly(ethylene glycol) graft copolymer is primarily controlled by drug diffusion through the intact polymeric membranes, irrespective of the type of starter core (consisting of microcrystalline cellulose or sugar, optionally coated with ethylcellulose). Importantly, the apparent diffusion coefficient of the drug in the macromolecular networks could easily be determined with thin free films and successfully be used to quantitatively predict the release rate from coated pellets. Thus, based on this knowledge and using the presented mathematical theories the development of new/ optimization of existing controlled drug delivery systems of this type can be significantly facilitated.


Assuntos
Celulose/análogos & derivados , Preparações de Ação Retardada/química , Portadores de Fármacos/química , Celulose/química , Diltiazem/química , Composição de Medicamentos , Estabilidade de Medicamentos , Modelos Químicos , Valor Preditivo dos Testes , Solubilidade
14.
Int J Pharm ; 368(1-2): 138-45, 2009 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-18996457

RESUMO

Instability during long term storage due to further gradual coalescence of the film remains one of the major challenges when using aqueous polymer dispersions for controlled release coatings. It has recently been shown that the addition of small amounts of poly(vinyl acetate)-poly(ethylene glycol)-graft-copolymer (PVA-PEG-graft-copolymer) to aqueous ethylcellulose dispersion provides long term stable drug release patterns even upon open storage under stress conditions in the case of theophylline matrix cores. However, the transferability of this approach to other types of drugs and starter cores exhibiting different osmotic activity is yet unknown. The aim of this study was to evaluate whether this novel approach is also applicable to freely water-soluble drugs and osmotically active sugar starter cores. Importantly, long term stable drug release profiles from coated diltiazem HCl-layered sugar cores could be achieved even upon open storage for 1 year under stress conditions (40 degrees C and 75% relative humidity). However, to provide desired drug release profiles the amount of added PVA-PEG-graft-copolymer must be adjusted. A minimal critical content of 10% (w/w) of this hydrophilic additive was identified, under which further polymer particle coalescence upon long term storage under stress conditions cannot be excluded. Potentially too rapid drug release can effectively be slowed down by increasing the coating level. Thus, adapting the polymer blend ratio and coating thickness desired and long term stable drug release profiles (even under stress conditions and open storage) can be provided for very different types of drugs and starter cores by the addition of small amounts of PVA-PEG-graft-copolymer to aqueous ethylcellulose dispersion.


Assuntos
Celulose/análogos & derivados , Preparações de Ação Retardada/química , Portadores de Fármacos/química , Polietilenoglicóis/química , Álcool de Polivinil/química , Celulose/química , Celulose/farmacocinética , Diltiazem/química , Portadores de Fármacos/farmacocinética , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Polietilenoglicóis/farmacocinética , Álcool de Polivinil/farmacocinética , Solubilidade , Comprimidos com Revestimento Entérico , Fatores de Tempo
15.
Eur J Pharm Biopharm ; 68(1): 2-10, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17881197

RESUMO

The major aims of this study were: (i) to prepare and characterize polymeric film coatings with pH-dependent properties for oral administration; and (ii) to better understand the underlying mass transport mechanisms upon exposure to simulated gastric and intestinal fluids. Propylene glycol alginate (containing free carboxylic groups) was chosen as a pH-sensitive film former, which was blended with different amounts of ethylcellulose (being water-insoluble throughout the gastro-intestinal tract). The water uptake kinetics of thin free films in 0.1M HCl and phosphate buffer pH 7.4 were monitored gravimetrically and quantitatively described using an appropriate analytical solution of Fick's law of diffusion. Interestingly, the addition of only a low percentage (2.5-10%) of propylene glycol alginate to ethylcellulose significantly increased both, the rate and extent of the films' water uptake, irrespective of the pH of the release medium. Importantly, diffusion was found to be the pre-dominant mass transport mechanism for all system compositions and types of release media. The apparent water diffusivity in the polymeric films could quantitatively be determined as a function of the polymer blend ratio. It significantly increased with increasing pH of the release medium, due to the presence of the free carboxylic groups in propylene glycol alginate. Also the dry mass loss of the polymer networks was much more pronounced at high compared to low pH. The differences in both water uptake as well as dry mass loss resulted in a clear pH-dependence of the drug release kinetics from coated pellets. Importantly, desired pH-sensitive release rates can easily be adjusted by varying the propylene glycol alginate content.


Assuntos
Alginatos/química , Celulose/análogos & derivados , Portadores de Fármacos/química , Celulose/química , Preparações de Ação Retardada , Difusão , Suco Gástrico/metabolismo , Concentração de Íons de Hidrogênio , Secreções Intestinais/metabolismo , Cinética , Teofilina/química , Água/metabolismo
16.
J Control Release ; 126(1): 26-33, 2008 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-18068259

RESUMO

The major aim of this study was to identify an easy tool to improve the long term stability of polymeric film coatings applied from aqueous dispersions. Drug release profiles from ethylcellulose-coated theophylline pellets were monitored during 6 months open storage under ambient and stress conditions ["room temperature/ambient relative humidity (RH)" and "40 degrees C/75%RH"]. The pellets were cured for 1 or 2 d at 60 degrees C or for 1 or 2 d at 60 degrees C/75%RH (followed by 1 d at 60 degrees C for drying). Drug release was measured in 0.1 M HCl and in phosphate buffer pH 7.4. Interestingly, the addition of only small amounts of poly(vinyl alcohol)-poly(ethylene glycol) graft copolymer provided stable drug release profiles under all the investigated conditions, irrespective of the type of release medium, coating level, polymer blend ratio and curing conditions. The addition of small amounts of propylene glycol alginate resulted in unaltered drug release kinetics during open storage under ambient conditions, but decreasing theophylline release rates during open storage under stress conditions, due to further gradual polymer particle coalescence. When adding small amounts of carrageenan to the ethylcellulose coatings, essentially stable theophylline release patterns (with slight variations) were obtained. As coating conditions were not optimized for each system, further work is necessary to distinguish polymer from process effects. The observed stabilizing effects of the investigated added polymers might be attributable to their hydrophilic nature, trapping water within the coatings during film formation and, thus, facilitating polymer particle coalescence. This new concept can be used to overcome one of the major practical obstacles associated with aqueous polymeric film coatings today: storage instability.


Assuntos
Celulose/análogos & derivados , Teofilina/química , Celulose/química , Preparações de Ação Retardada , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Excipientes/química , Umidade , Solubilidade , Temperatura
17.
J Control Release ; 119(2): 182-9, 2007 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-17391796

RESUMO

The aim of this study was to provide an easy and efficient tool to adjust desired drug release kinetics from (aqueous) ethylcellulose-coated solid dosage forms and to better understand the underlying mass transport mechanisms. Pure ethylcellulose films are poorly permeable for many substances and can result in very low release rates for certain drugs from coated dosage forms, if the film coatings are completely formed and remain intact upon exposure to the release media. To increase the permeability of the polymeric membranes, different amounts of a water-soluble poly(vinyl alcohol)-poly(ethylene glycol) graft copolymer (PVA-PEG graft copolymer) were added to an aqueous ethylcellulose dispersion (Aquacoat ECD). Importantly, the presence of only a low percentage of this hydrophilic copolymer significantly increased the resulting water uptake rate and extent, dry weight loss and drug permeability of the films. In contrast to hydroxypropyl methylcellulose (HPMC), the PVA-PEG graft copolymer does not cause flocculation of the colloidal coating dispersion (leading to potentially variable release rates). Interestingly, the transport of water as well as of the model drug theophylline through the polymeric networks was primarily controlled by pure diffusion. The penetration kinetics could be quantitatively described by Fick's law of diffusion, irrespective of the type of release medium and PVA-PEG graft copolymer content. Most important from a practical point of view, a broad spectrum of pH-independent drug release rates can easily be obtained from drug-loaded pellets by simply varying the PVA-PEG graft copolymer content. An appropriate curing step after coating is required, but interestingly the investigated curing conditions (differing in time and relative humidity) resulted in very similar drug release patterns, indicating that stable film structures are likely to be achieved.


Assuntos
Celulose/análogos & derivados , Celulose/química , Celulose/farmacocinética , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Polietilenoglicóis/química , Polietilenoglicóis/farmacocinética , Álcool de Polivinil/química , Álcool de Polivinil/farmacocinética , Comprimidos com Revestimento Entérico
18.
Clin Nephrol ; 66(5): 336-47, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17140163

RESUMO

BACKGROUND: The Kidney Disease Outcomes Quality Initiative (K/DOQI) treatment guidelines for managing dyslipidemia in patients with chronic kidney disease (CKD) designate CKD as a high-risk category for coronary heart disease and, in Stage 5 CKD patients, recommend maintaining low-density lipoprotein (LDL) < 100 mg/dl and, for patients with hypertriglyceridemia (> or = 200 mg/ dl), non-high-density lipoprotein (non-HDL) < 130 mg/dl, the latter to achieve very low-density lipoprotein (VLDL) < 30 mg/dl. More recently, the National Cholesterol Education Program has recommended an LDL target of < 70 mg/dl for high-risk patients. AIMS: The purposes of this study were: to document the point prevalence of dyslipidemia in CKD patients at hemodialysis inception, prior to potential impact of dialysis treatments; to assess the hypothesis that non-HDL serves as a reliable surrogate marker for elevated VLDL; to examine the performance of K/DOQI guidelines in treating dyslipidemia; and to evaluate the utility of non-HDL as an alternative primary trigger/target of lipid-lowering therapy in Stage 5 CKD patients. METHODS: Consistent with K/DOQI guidelines, lipid levels drawn immediately prior to hemodialysis sessions, thus possibly non-fasting, were analyzed in 21,893 incident dialysis patients by laboratory measurements of triglycerides, total cholesterol, and HDL and from calculated values of non-HDL, LDL, VLDL and intermediate-density lipoprotein. RESULTS: Prevalence of dyslipidemia, by guideline definitions, was 82%, predominantly manifested by elevated triglycerides (52%) and VLDL (52%) and decreased HDL (51%), with less frequent elevations of LDL (40%) and total cholesterol (24%). Non-HDL > or = 130 mg/dl was neither a sensitive (61%) nor specific (75%) marker for elevated VLDL. There was a striking disparity between the high prevalence of dyslipidemia and the percentage of dyslipidemic patients qualified by K/DOQI guidelines for therapy. Non-HDL > or = 130 mg/dl was as effective in qualifying dyslipidemic patients for lipid-lowering therapy (54%) as the entire K/DOQI treatment algorithm (57%). Lowering the trigger of non-HDL to > or = 100 mg/dl would qualify 81% of dyslipidemic patients for treatment while offering the important advantage of being uninfluenced by the non-fasting state. CONCLUSIONS: In Stage 5 CKD patients at hemodialysis inception, dyslipidemia is highly prevalent with predominance of the atherogenic triad (hypertriglyceridemia, elevated VLDL and reduced HDL). Non-HDL is a poor surrogate marker for VLDL. As a valid non-fasting lipid parameter, non-HDL alone at the level of > or = 130 mg/dl qualifies dyslipidemic Stage 5 CKD patients for therapy as effectively as the K/DOQI guidelines. Setting the non-HDL trigger/target cut-off at 100 mg/dl overcomes the insensitivity of non-HDL as a marker for atherogenic lipoproteins represented by the VLDL designation while ensuring more aggressive lipid-lowering therapy for Stage 5 CKD patients at high risk for cardiovascular events. Accordingly, non-HDL of 100 mg/dl is proposed as the all-encompassing primary trigger/target of lipid-lowering therapy in high-risk Stage 5 CKD patients, particularly those patients on dialysis in whom lipid samples obtained before dialysis cannot be guaranteed to be fasting.


Assuntos
Colesterol/sangue , Dislipidemias/sangue , Falência Renal Crônica/sangue , Diálise Renal , Idoso , HDL-Colesterol/classificação , LDL-Colesterol/sangue , VLDL-Colesterol/sangue , Dislipidemias/epidemiologia , Feminino , Humanos , Incidência , Falência Renal Crônica/complicações , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Guias de Prática Clínica como Assunto , Prevalência , Estatísticas não Paramétricas , Triglicerídeos/sangue
19.
J Ind Microbiol Biotechnol ; 31(5): 204-8, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15221666

RESUMO

A fractional factorial design with eight trials was applied to select and model the effects of major factors, individually and in combination, on improving Tetrahymena thermophila growth and enzyme production. Regulated pH at 6.8 and olive oil at 0.5% (v/v) showed positive effects on fermentation, and increased cell growth parameters including generation time and maximal population formation. Lipase and protease production were also improved by these factors and were favoured by cultivation of Tetrahymena in darkness. This statistical experiment offers a beneficial and rapid screening procedure to select the most effective combination of factors influencing fermentation processes.


Assuntos
Biotecnologia/métodos , Hidrolases/biossíntese , Tetrahymena thermophila/enzimologia , Tetrahymena thermophila/crescimento & desenvolvimento , Animais , Fermentação , Substâncias de Crescimento/farmacologia , Modelos Estatísticos , Tetrahymena thermophila/efeitos dos fármacos
20.
Br Poult Sci ; 45(6): 775-86, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15697017

RESUMO

1. Protein utilisation and turnover were measured in male chickens sampled from a line selected for high breast yield and a randombred control line (lines QL and CL, experiment 1) and in male chickens sampled from lines selected for either high or low abdominal fatness (lines FL and LL, experiment 2). In each experiment, 18 birds per line were given iso-energetic (12.9 MJME/kg) diets containing either 120 or 220 g CP/kg from 21 to 29 d (experiment 1) and 33 to 43 d (experiment 2). 2. Measurements were made of growth rate, food intake, body composition, excreta production and Ntau-methylhistidine excretion as a measure of myofibrillar protein breakdown, and fractional rates (%/d) of protein deposition, breakdown and synthesis were calculated. 3. In experiment 1, there were no significant differences between the line means for the fractional measures of protein turnover, but there was marked differential response in the two lines in the fractional rates of protein deposition, breakdown and synthesis, to increase in protein intake. The positive slope of the regressions of fractional (%/d) protein deposition and synthesis rates on protein intake (g/d/kg BW) were approximately 1.4- and 2.0-fold higher respectively in the QL than the CL line birds, and the negative slope of the regression of fractional breakdown rate on protein intake was approximately threefold greater in the CL than the QL line birds. 4. In experiment 2, fractional deposition rate was 6.2% lower, but fractional breakdown rate 9.4% higher in the LL than the FL birds, whilst there was essentially no difference in response of the FL and LL birds in the components of protein turnover to increase in protein intake. Line differences in deposition and breakdown rates were thus a reflection of the considerably higher (20%) food and hence protein intake in the FL than the LL birds. 5. The differential line responses in protein turnover in the two experiments suggest that selection for increased breast muscle yield and for reduced body fatness manipulate different physiological pathways in relation to protein turnover, but neither selection strategy results in an improvement in net protein utilisation at typical levels of protein intake by birds on commercial broiler diets, through a reduction in protein breakdown rate.


Assuntos
Composição Corporal/genética , Galinhas/genética , Proteínas na Dieta/metabolismo , Tecido Adiposo/fisiologia , Ração Animal , Animais , Composição Corporal/fisiologia , Galinhas/fisiologia , Dieta , Ingestão de Alimentos , Masculino , Músculo Esquelético/fisiologia , Aumento de Peso
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