Rice Husk, Brewer's Spent Grain, and Vine Shoot Trimmings as Raw Materials for Sustainable Enzyme Production.

Solid by-products with lignocellulosic structures are considered appropriate substrates for solid-state fermentation (SSF) to produce enzymes with diverse industrial applications. In this work, brewer's spent grain (BSG), rice husk (RH), and vine shoot trimmings (VSTs) were employed as substrates in SSF with Aspergillus niger CECT 2088 to produce cellulases, xylanases, and amylases. The addition of 2% (NH4)2SO4 and 1% K2HPO4 to by-products had a positive effect on enzyme production. Substrate particle size influenced enzyme activity and the overall highest activities were achieved at the largest particle size (10 mm) of BSG and RH and a size of 4 mm for VSTs. Optimal substrate composition was predicted using a simplex centroid mixture design. The highest activities were obtained using 100% BSG for ß-glucosidase (363 U/g) and endo-1,4-ß-glucanase (189 U/g), 87% BSG and 13% RH for xylanase (627 U/g), and 72% BSG and 28% RH for amylase (263 U/g). Besides the optimal values found, mixtures of BSG with RH or VSTs proved to be alternative substrates to BSG alone. These findings demonstrate that SSF bioprocessing of BSG individually or in mixtures with RH and VSTs is an efficient and sustainable strategy to produce enzymes of significant industrial interest within the circular economy guidelines.

Exploring the use of hexadecane by Yarrowia lipolytica: Effect of dissolved oxygen and medium supplementation.

This work aimed to evaluate the effect of medium composition and volumetric oxygen transfer coefficient (kLa) on Y. lipolytica growth and production of microbial lipids and enzymes from hexadecane. In the stirred tank bioreactor, increasing kLa from 11 h-1 to 132 h-1 improved the hexadecane assimilation rate, biomass concentration, and lipids synthesis (0.90 g·L-1). A cost-effective hexadecane-based medium supplemented with corn steep liquor and a low amount of ammonium sulfate boosted lipids production up to 2.1 g·L-1, composed of palmitic, palmitoleic, oleic, and linoleic acids. The unsaturated/saturated fraction was dependent on the C/N ratio. Lipids of Y. lipolytica CBS 2075 are promising feedstock for animal feed, food additives, or the biodiesel industry. Simultaneous synthesis of extracellular lipase and protease from hexadecane was observed, which is a new feature that was not previously reported. The highest enzyme activity was obtained at the highest C/N ratio conditions. These results open new perspectives on the application of Y. lipolytica-based cultures for the biotransformation of hexadecane-polluted streams into valuable compounds, fulfilling an interesting strategy towards the circular economy concept.

Yarrowia lipolytica produces lipid-rich biomass in medium mimicking lignocellulosic biomass hydrolysate.

In recent years, lignocellulosic biomass has become an attractive low-cost raw material for microbial bioprocesses aiming the production of biofuels and other valuable chemicals. However, these feedstocks require preliminary pretreatments to increase their utilization by microorganisms, which may lead to the formation of various compounds (acetic acid, formic acid, furfural, 5-hydroxymethylfurfural, p-coumaric acid, vanillin, or benzoic acid) with antimicrobial activity. Batch cultures in microplate wells demonstrated the ability of Yarrowia strains (three of Y. lipolytica and one of Y. divulgata) to grow in media containing each one of these compounds. Cellular growth of Yarrowia lipolytica W29 and NCYC 2904 (chosen strains) was proven in Erlenmeyer flasks and bioreactor experiments where an accumulation of intracellular lipids was also observed in culture medium mimicking lignocellulosic biomass hydrolysate containing glucose, xylose, acetic acid, formic acid, furfural, and 5-HMF. Lipid contents of 35% (w/w) and 42% (w/w) were obtained in bioreactor batch cultures with Y. lipolytica W29 and NCYC 2904, respectively, showing the potential of this oleaginous yeast to use lignocellulosic biomass hydrolysates as feedstock for obtaining valuable compounds, such as microbial lipids that have many industrial applications. KEY POINTS: • Yarrowia strains tolerate compounds found in lignocellulosic biomass hydrolysate • Y. lipolytica consumed compounds found in lignocellulosic biomass hydrolysate • 42% (w/w) of microbial lipids was attained in bioreactor batch cultures.

Bio-oil production for biodiesel industry by Yarrowia lipolytica from volatile fatty acids in two-stage batch culture.

Microbial lipids-derived biodiesel is garnering much attention owing to its potential to substitute diesel fuel. In this study, lipid accumulation by Yarrowia lipolytica from volatile fatty acids (VFAs) was studied in a lab-scale stirred tank bioreactor. In batch cultures, Y. lipolytica NCYC 2904 was able to grow in 18 g·L-1 of VFAs (acetate, propionate, and butyrate), and the addition of a co-substrate (glucose) led to a fivefold improvement in lipid concentration. Furthermore, the two-stage batch culture (growth phase in glucose (1st stage) followed by a lipogenic phase in VFAs (2nd stage)) was the best strategy to obtain the highest lipid content in the cells (37%, w/w), with aeration conditions that kept dissolved oxygen concentration between 40% and 50% of saturation during the lipogenic phase. The estimated fuel properties of biodiesel produced from Y. lipolytica NCYC 2904 lipids are comparable with those of the biodiesel produced from vegetable oils and are in accordance with the international standards (EN 14214 and ASTM D6751). The cultivation strategies herein devised enable a sustainable, eco-friendly, and economical production of microbial lipids, based on feedstocks such as VFAs that can be derived from the acidogenic fermentation of organic wastes. KEY POINTS: • Addition of glucose to VFAs enhances lipids in Y. lipolytica in batch cultures • Two-stage batch culture - growth in glucose followed by VFAs pulse - rises lipids • Dissolved oxygen of 40-50% of saturation is crucial at the lipogenic phase.

Yarrowia lipolytica as a biorefinery platform for effluents and solid wastes valorization - challenges and opportunities.

Due to its physiological and enzymatic features, Yarrowia lipolytica produces several valuable compounds from a wide range of substrates. Appointed by some authors as an industrial workhorse, Y. lipolytica has an extraordinary ability to use unrefined and complex low-cost substrates as carbon and nitrogen sources, aiding to reduce the waste surplus and to produce added-value compounds in a cost-effective way. Dozens of review papers regarding Y. lipolytica have been published till now, proving the interest that this yeast arouses in the scientific community. However, most of them are focused on metabolic pathways involved in substrates assimilation and product formation, or the development of synthetic biology tools in order to obtain engineered strains for biotechnological applications. This paper provides an exhaustive and up-to-date revision on the application of Y. lipolytica to valorize liquid effluents and solid wastes and its role in developing cleaner biotechnological approaches, aiming to boost the circular economy. Firstly, a general overview about Y. lipolytica is introduced, describing its intrinsic features and biotechnological applications. Then, an extensive survey of the literature regarding the assimilation of oily wastes (waste cooking oils, oil cakes and olive mill wastewaters), animal fat wastes, hydrocarbons-rich effluents, crude glycerol and agro-food wastes by Y. lipolytica strains will be discussed. This is the first article that brings together the environmental issue of all such residues and their valorization as feedstock for valuable compounds production by Y. lipolytica. Finally, it will demonstrate the potential of this non-conventional yeast to be used as a biorefinery platform.

Factors affecting microbial lipids production by Yarrowia lipolytica strains from volatile fatty acids: Effect of co-substrates, operation mode and oxygen.

Volatile fatty acids (VFAs), which can be generated by acidogenesis of organic wastes, are important building blocks for chemicals production, and are intermediates in many bioprocesses such as microbial lipids production. Important factors affecting the bioconversion of VFAs (acetate, propionate and butyrate) by Yarrowia lipolytica W29 and NCYC 2904 for growth and lipids accumulation were studied. Yarrowia lipolytica grew efficiently in VFAs-based media, but lipids production was enhanced by the addition of co-substrates (glucose or glycerol) in batch cultures. A two-stage batch culture - growth phase on glucose, followed by VFAs addition, improved lipids accumulation. Lipids concentrations of 2.3 g·L-1 and 3.5 g·L-1 were obtained with this mode of operation, with addition of 18 g·L-1 VFAs, for Y. lipolytica W29 and NCYC 2904, respectively. For the first time, it was demonstrated that oxygen mass transfer is a crucial factor for lipids production by Y. lipolytica from VFAs. Intracellular lipids produced by Y. lipolytica strains were mainly composed by oleic and linoleic acids, similar to common vegetable oils, making these lipids suitable for biodiesel production. Moreover, margaric acid, which may improve biodiesel properties, was only detected in propionate medium. The strategies studied herein will contribute to the feasibility of using VFAs as low-cost feedstock for microbial lipids production by Y. lipolytica strains.

A expectativa do casal sobre o plano de parto / The couple's expectations for the birth plan / La expectativa de la pareja sobre el plan de parto

Enquadramento: O plano de parto (PP) é um processo reflexivo e de tomada de decisão do casal grávido, exposto num documento escrito, promovendo uma melhor comunicação com os profissionais de saúde e a autonomia das mulheres. Objetivo: O presente estudo, inserido numa investigação mais vasta, teve como objetivo descrever a expectativa do casal sobre o PP. Metodologia: Estudo qualitativo, tipo exploratório-descritivo. Os participantes foram 10 casais que frequentaram o programa de preparação para o parto de uma maternidade do centro de Portugal. O instrumento de recolha de dados foi a entrevista semiestruturada e a análise dos dados, realizada com o método de análise de conteúdo de Bardin e com o software NVivo10. Resultados: Metade dos participantes não conheciam o conceito de PP, mas reconhecem a importância da discussão das suas preferências com um Enfermeiro Especialista em Saúde Materna e Obstétrica para uma experiência de parto positiva. Conclusão: Este estudo pode permitir a inovação e melhoria na assistência segura à mulher/casal, respondendo eficazmente às suas expectativas e necessidades.

Background: The birth plan (BP) is a reflexive and decision-making process of the expectant couple, exposed in a written document, allowing a better communication with health professionals and the women's autonomy. Objective: The present study, inserted in a larger investigation, aimed to describe the couple's expectation about BP. Methodology: A qualitative, exploratory-descriptive study. Participants were 10 couples who attended the Parenthood and Birth Preparation Program at a maternity in central Portugal. The data collection instrument was the semi-structured interview and data analysis performed using the Bardin content analysis method and the NVivo10 software. Results: Half of the participants did not know the concept of the Birth Plan, but recognize the importance of discussing their preferences with a midwife for a positive childbirth experience. Conclusion: This study allows innovation and improvement in safe care for women/ couples, in order to respond to their expectations and needs.

Marco contextual: El plan de parto (PP) es un proceso reflexivo y de toma de decisiones para la pareja embarazada, establecido en un documento escrito, que promueve una mejor comunicación con los profesionales de la salud y la autonomía de la mujer. Objetivo: Este estudio, incluido en una investigación más amplia, tuvo como objetivo describir las expectativas de la pareja sobre el PP. Metodología: Estudio cualitativo, de tipo exploratorio-descriptivo. Los participantes fueron 10 parejas que asistieron al programa de preparación al parto de un servicio de maternidad en el centro de Portugal. El instrumento de recogida de datos fue la entrevista semiestructurada y el análisis de datos se realizó con el método de análisis de contenido de Bardin y con el software NVivo10. Resultados: La mitad de los participantes no estaban familiarizados con el concepto de PP, pero reconocieron la importancia de discutir sus preferencias con una matrona para tener una experiencia positiva en el parto. Conclusión: Este estudio puede permitir innovar y mejorar la atención segura a las mujeres/parejas, al responder eficazmente a sus expectativas y necesidades.

A expectativa do casal sobre o plano de parto / The couple's expectation of the birth plan

O Plano de Parto (PP) é um processo reflexivo e de tomada de decisão do casal grávido, exposto num documento escrito onde expressa os seus desejos e expetativas relativamente ao seu parto. Este tipo de documento permite uma melhor comunicação com os profissionais de saúde e têm-se tornado cada vez mais popular com o propósito de promover a autonomia das mulheres, sendo já vários os estudos que concluem que o seu uso pode influenciar o tipo de parto, nomeadamente na diminuição do número de cesarianas, contribuindo também para o aumento da satisfação, eficácia e empoderamento das mulheres. Tendo como objetivo descrever a expectativa do casal sobre o PP e, especificamente, a expetativa da mãe e do pai, delineou-se um estudo qualitativo, do tipo exploratório-descritivo. A população consistiu nos casais que frequentam o Programa de Preparação para o Parto de uma maternidade central do centro do país, cuja amostra foi selecionada segundo uma amostragem não probabilística por conveniência. O instrumento de colheita de dados (devidamente aprovada pelas comissões de ética, da maternidade e da UICISA-E) foi a entrevista semi-estruturada. A análise dos dados foi realizada de acordo com o método de análise de conteúdo de Bardin e com o software NVivo 10. Da análise do discurso dos participantes emergiram, quer na mãe, quer no pai, dois domínios: Envolvimento/Planeamento do Nascimento e a Tomada de Decisão sobre o PP. Do primeiro emergiram quatro categorias: Experiência de Nascimento, Ambiente e Conforto, Empoderamento nas Intervenções e Primeiro Contacto com o Bebé. Do domínio da Tomada de Decisão sobre o PP emergiram duas categorias que representam o Conhecimento sobre o Conceito de PP e o Valor Atribuído ao PP. A profundidade e complexidade da análise abordou ainda mais três níveis de subcategorias emergentes destas principais. Estamos convictas de que os resultados decorrentes desta investigação podem ser usados para inovar e melhorar os Programas de Preparação para o Parto e Parentalidade, no sentido de responder às expectativas e necessidades individuais dos casais, contribuindo para a reflexão e implementação de modelos de assistência ao parto que privilegiem condutas reconhecidamente científicas e seguras, ampliando o poder de escolha dos casais, de forma a que estes possam exercer a sua maternidade e paternidade com segurança e bem estar.

Microbial lipids and added value metabolites production by Yarrowia lipolytica from pork lard.

Yarrowia lipolytica is a suitable microbial platform to convert low-value hydrophobic substrates into microbial oils and other important metabolites. In this work, this yeast species was used to simultaneously synthetize ex novo lipids and produce citric acid and lipase from animal fat (pork lard) adding higher value to the low-cost fatty substrate. The effect of pH, lard concentration, arabic gum concentration and oxygen mass transfer rate (OTR) on lipids accumulation on Y. lipolytica batch cultures was assessed by an experimental design based on Taguchi method. OTR was by far the most influential parameter in the range of 96mgL-1h-1-480mgL-1h-1. A bio-modification of initial lipidic substrate was observed and, depending on the nutritional and operational conditions, specialty lipids with specific composition and high added-value were obtained. The unsaturated-to-saturated fatty acids ratio of these microbial lipids is higher than in initial substrate, which indicates that they are more suitable than animal fat for food additives. Moreover, the simultaneous induction of lipase and citric acid by Y. lipolytica growing in animal fat demonstrates that a biorefinery approach may be designed based on animal fat raw material.

In vivo biodistribution of antihyperglycemic biopolymer-based nanoparticles for the treatment of type 1 and type 2 diabetes.

This study aimed to assess the biodistribution of antihyperglycemic insulin-loaded alginate/dextran sulfate-based nanoparticles dual coated with chitosan and technetium-99m-albumin (99mTc-BSA) after oral administration. The oral administration of 50IU/kg insulin-loaded nanoparticles to type 1 diabetic rats showed prolonged antihyperglycemic effects up to 12h and relative pharmacological availability of 5.04% comparing to the subcutaneous administration. The oral antihyperglycemic effect was further compared between type 1 and type 2 diabetic models by the intraperitoneal glucose tolerance test, revealing that the effect lasted longer in the type 1 diabetic model. 99mTc-BSA revealed to be a good nanoparticles' tracer since there was no systemic absorption and 99mTc-BSA-nanoparticles were capable of increasing their residence time in the intestinal epithelium of balb-c mice when compared with 99mTc-BSA biodistribution. Thus, this biopolymeric-based delivery nanoparticulate system is a promising tool for the therapy of type 1 and type 2 diabetic individuals and prevention of T1D.

Preparation methods and applications behind alginate-based particles.

INTRODUCTION: Alginate-based particles have emerged as one of the most extensively searched drug delivery platforms due to their inherent properties, including good biocompatibility and biodegradability. Moreover, the low price, easy availability, natural origin, versatility and sol-gel transition properties, make alginate an ideal candidate to produce particles with different applications. Several techniques have been developed and optimized to prepare microparticles and nanoparticles in order to achieve more rational, coherent, efficient and cost-effective procedures. Alginate represents a suitable choice concerning delivery systems' safety, and therefore alginate-based particles have shown to be useful in the field of drug delivery with a special focus on biological encapsulants. Area covered: This review will provide an overview of alginate-based delivery systems, covering the innovative preparation methods of the last decade, the advantages and disadvantages of the most used methods, their wide diversity of applications and safety concerns. Expert opinion: The progression of nanotechnology over the last decades has stimulated the refinement of former microencapsulation methods and the exploration of new approaches towards the submicron scale with increased attention being focused on the safety of nanoparticles and product performance. Therefore, the design and optimization of the preparation methods of alginate-based microparticles and nanoparticles as well as their nontoxicity, biocompatibility and biodegradability to reach the desired application have been widely explored.

Dual chitosan/albumin-coated alginate/dextran sulfate nanoparticles for enhanced oral delivery of insulin.

The potential of nanoparticles (NPs) to overcome the barriers for oral delivery of protein drugs have led to the development of platforms capable of improving their bioavailability. However, despite the progresses in drug delivery technologies, the success of oral delivery of insulin remains elusive and the disclosure of insulin mechanisms of absorption remains to be clarified. To overcome multiple barriers faced by oral insulin and to enhance the insulin permeability across the intestinal epithelium, here insulin-loaded alginate/dextran sulfate (ADS)-NPs were formulated and dual-coated with chitosan (CS) and albumin (ALB). The nanosystem was characterized by its pH-sensitivity and mucoadhesivity, which enabled to prevent 70% of in vitro insulin release in simulated gastric conditions and allowed a sustained insulin release following the passage to simulated intestinal conditions. The pH and time-dependent morphology of the NPs was correlated to the release and permeation profile of insulin. Dual CS/ALB coating of the ADS-NPs demonstrated augmented intestinal interactions with the intestinal cells in comparison to the uncoated-NPs, resulting in a higher permeability of insulin across Caco-2/HT29-MTX/Raji B cell monolayers. The permeability of the insulin-loaded ALB-NPs was reduced after the temperature was decreased and after co-incubation with chlorpromazine, suggesting an active insulin transport by clathrin-mediated endocytosis. Moreover, the permeability inhibition with the pre-treatment with sodium chlorate suggested that the interaction between glycocalix and the NPs was critical for insulin permeation. Overall, the developed nanosystem has clinical potential for the oral delivery of insulin and therapy of type 1 diabetes mellitus.

Probing insulin bioactivity in oral nanoparticles produced by ultrasonication-assisted emulsification/internal gelation.

Alginate-dextran sulfate-based particles obtained by emulsification/internal gelation technology can be considered suitable carriers for oral insulin delivery. A rational study focused on the emulsification and particle recovery steps was developed in order to reduce particles to the nanosize range while keeping insulin bioactivity. There was a decrease in size when ultrasonication was used during emulsification, which was more pronounced when a cosurfactant was added. Ultrasonication add-on after particle recovery decreased aggregation and led to a narrower nanoscale particle-size distribution. Insulin encapsulation efficiency was 99.3%±0.5%, attributed to the strong pH-stabilizing electrostatic effect between insulin and nanoparticle matrix polymers. Interactions between these polymers and insulin were predicted using molecular modeling studies through quantum mechanics calculations that allowed for prediction of the interaction model. In vitro release studies indicated well-preserved integrity of nanoparticles in simulated gastric fluid. Circular dichroism spectroscopy proved conformational stability of insulin and Fourier transform infrared spectroscopy technique showed rearrangements of insulin structure during processing. Moreover, in vivo biological activity in diabetic rats revealed no statistical difference when compared to nonencapsulated insulin, demonstrating retention of insulin activity. Our results demonstrate that alginate-dextran sulfate-based nanoparticles efficiently stabilize the loaded protein structure, presenting good physical properties for oral delivery of insulin.

Why most oral insulin formulations do not reach clinical trials.

Oral insulin able to induce an efficient antihyperglycemic effect either to replace or complement diabetes mellitus therapy is the major goal of health providers, governments and diabetic patients. Oral therapy is associated not only with the desire to exclude needles from the daily routine of diabetic patient but also with the physiological provision of insulin they would get. Despite numerous efforts over the past few decades to develop insulin delivery systems, there is still no commercially available oral insulin. The reasons why the formulations developed to administer insulin orally fail to reach clinical trials are critically discussed in this review. The principal features of nanoformulations used so far are also addressed as well as the undergoing clinical trials.

Intestinal uptake of insulin nanoparticles: facts or myths?

The oral route is the most suitable and physiological delivery route. Oral insulin delivery would minimize the health hazard implied in repeated injection, surpass complications arising from the need for sterile techniques associated with parenteral formulations and provide better glucose homeostasis. However, it is limited by various physiological barriers and still remains a scientific challenge. The desire to deliver insulin by the oral route in a conveniently and effectively way has led to the intense investigation of new delivery systems. Nanodelivery systems have been proposed to enhance the bioavailability of insulin after oral administration. This review article describes the gastrointestinal barriers to oral insulin delivery, including chemical, enzymatic and absorption barriers. The potential transport mechanisms of insulin delivered by nanoparticles across the intestinal epithelium are also addressed. Finally, how nanoparticles characteristics affect insulin pharmacological activity and bioavailability is discussed.

Enhanced heterologous protein production in Pichia pastoris under increased air pressure.

Pichia pastoris is a widely used host for the production of heterologous proteins. In this case, high cell densities are needed and oxygen is a major limiting factor. The increased air pressure could be used to improve the oxygen solubility in the medium and to reach the high oxygen demand of methanol metabolism. In this study, two P. pastoris strains producing two different recombinant proteins, one intracellular (ß-galactosidase) and other extracellular (frutalin), were used to investigate the effect of increased air pressure on yeast growth in glycerol and heterologous protein production, using the methanol AOX1-inducible system. Experiments were carried out in a stainless steel bioreactor under total air pressure of 1 bar and 5 bar. The use of an air pressure raise of up to 5 bar proved to be applicable for P. pastoris cultivation. Moreover, no effects on the kinetic growth parameters and methanol utilization (Mut) phenotype of strains were found, while an increase in recombinant ß-galactosidase-specific activity (ninefold) and recombinant frutalin production was observed. Furthermore, the air pressure raise led to a reduction in the secreted protease specific activity. This work shows for the first time that the application of an air pressure of 5 bar may be used as a strategy to decrease protease secretion and improve recombinant protein production in P. pastoris.

Over-pressurized bioreactors: application to microbial cell cultures.

In industrial biotechnology, microbial cultures are exposed to different local pressures inside bioreactors. Depending on the microbial species and strains, the increased pressure may have detrimental or beneficial effects on cellular growth and product formation. In this review, the effects of increased air pressure on various microbial cultures growing in bioreactors under moderate total pressure conditions (maximum, 15 bar) will be discussed. Recent data illustrating the diversity of increased air pressure effects at different levels in microbial cells cultivation will be presented, with particular attention to the effects of oxygen and carbon dioxide partial pressures on cellular growth and product formation, and the concomitant effect of oxygen pressure on antioxidant cellular defense mechanisms.

Intestinal absorption of insulin nanoparticles: contribution of M cells.

Nanodelivery systems have been extensively studied as a strategy for the effective treatment of type 1 diabetes in animal models. Nanoparticle formulations have been shown to contribute to increased intestinal absorption of insulin according to established pathways. It is important to determine whether intestinal absorption of the hormone, specifically occurs through a privileged pathway that is favored because of particular properties of the nanoparticles. Confocal fluorescence microscopy has revealed that nanoparticles-based oral insulin delivery in intestinal tissues causes their accumulation in Peyer's patches. To quantify the preponderance of M cells involved in the overall absorption of insulin in the intestine, in vitro and in vivo results of insulin-loaded nanoparticles were analyzed and criticized based on the utilized method and whether it has translational impact for the treatment of diabetes in humans. The degree of insulin nanoparticles uptake will be interpreted for its effectiveness in the prevention/treatment of other pathologies. FROM THE CLINICAL EDITOR: This study investigates nano-formulation based insulin delivery through the oral route, with particular attention to their accumulation in Peyer patches and the role of M-cells in their absorption. While oral delivery of insulin would be an important step from the standpoint of convenience, accurate dosing and issues of potential toxicity need to be considered before clinical translation of this method.

Development of a doxazosin and finasteride transdermal system for combination therapy of benign prostatic hyperplasia.

The treatment of benign prostatic hyperplasia can be accomplished by the use of different drugs including, doxazosin, an α-1 adrenergic antagonist, and finasteride (FIN), a 5-α reductase inhibitor. Traditionally, treatments using these drugs have been administered as either a mono or combination therapy by the oral route. A transdermal delivery system optimized for doxazosin and FIN combination therapy would provide increased patient adherence and facilitate dose adjustment. Doxazosin base (DB) was prepared from doxazosin mesylate and characterized together with FIN, by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The permeation enhancers, azone and lauric acid, and the gelling agents, hydroxypropyl cellulose (HPC) and Poloxamer 407 (P407), were evaluated to determine their ability to promote in vitro permeation of drugs through the pig ear epidermis. Successful preparation of DB was confirmed by evaluating the XRD, DSC, and NMR patterns and in vitro studies revealed that 3% (w/w) azone was the best permeation enhancer. When P407 gel was compared with HPC gel, it showed reduced lag time and promoted higher permeation of both drugs. This may be because of the interactions of the former with the stratum corneum, which disorganizes the lipid structure and consequently promotes higher drug permeation.

Comparison of Yarrowia lipolytica and Pichia pastoris cellular response to different agents of oxidative stress.

Yeast cells exposed to adverse conditions employ a number of defense mechanisms in order to respond effectively to the stress effects of reactive oxygen species. In this work, the cellular response of Yarrowia lipolytica and Pichia pastoris to the exposure to the ROS-inducing agents' paraquat, hydrogen peroxide, and increased air pressure was analyzed. Yeast cells at exponential phase were exposed for 3 h to 1 mM paraquat, to 50 mM H2O2, or to increased air pressure of 3 or 5 bar. For both strains, the cellular viability loss and lipid peroxidation was lower for the cells exposed to increased air pressure than for those exposed to chemical oxidants. The glutathione induction occurred only in Y. lipolytica strain and reached the highest level as a response to PQ exposure. In general, antioxidant enzymes were more expressed in Y. lipolytica than in P. pastoris. The enzyme superoxide dismutase was induced in both strains under all the oxidant conditions but was dependent on the cellular growth phase, being undetectable in non-growing cells, whereas glutathione reductase was more induced in those conditions. Hydrogen peroxide was the most efficient inducer of catalase. Both yeast cultures underwent no cellular growth inhibition with increased air pressure, indicating that these yeast species were able to adapt to the oxidative stressful environment.