Multifunctional enzymatically-generated hydrogel platforms for chronic wound application

Tesi per compendi d'articles, amb dues seccions retallades per drets de l'editorChronic wounds became burdensome problem of worldwide healthcare systems, along with the increased elderly population, which is the most vulnerable risk group, predisposed to their development. Chronic wounds represent a “silent epidemic” that affect a large fraction of the population and are often regarded as a comorbid condition. Statistical surveys indicated that 1-2 % of the population in developed countries will suffer from chronic wounds during their lifetime. Contemporary clinical treatment involves a combination of techniques and procedures aiming at eradication of wound chronicity and switching the biochemical entities to normal wound healing. In this regard, wound dressings have been affirmed and widely accepted as integral part of wound healing therapies. Wound care, by using dressings dates from ancient times, when for instance ancient egyptians applied and arranged bandages. Nowadays, the market is dominated by dressings, which only function besides a simple physical barrier is to balance the wound moisture by either absorbing excess exudates or providing moisture environment. However, the multifactorial nature of chronic wounds often renders this single-factor directed therapy as low or non-effective, aggravating the patient outcome. Thus, the demands for expanding the treatment options to more effective therapy brought about the development of bioactive dressings. These dressings should not only protect the wound and control the wound moisture, but also interact with various adverse wound constituents, modulating their bio-activities in favor of healing. Materials with inherent wound healing features are highly desireable and more attention to such materials among the research communities has lead to the design of wound dressings with improved characteristics. However, amongst the myriad novel dressings synthesized, there is still lack of universal dressing with a panel of features able to address most of the devastating chronic wound constituents. The lack of such on-market dressing, lead to huge economical burden of the healthcare systems, holding significant part of their budgets. Development of universal multifunctional dressing, appropriate for management of many types of chronic wounds will boost the health systems to minimize the costs and improve the quality of patient’s life. This thesis develops multifunctional biopolymer-based hydrogel materials as a bioactive platform with appropriate exploitation characteristics for treatment of chronic wound. To this end, hydrogels were developed by using environmentally benign approach, based on enzymatic reactions. Intrinsically bioactive biopolymer chitosan which served as a matrix, was modified with thiol groups and further in situ enzymatically crosslinked with two different natural polyphenols. The incorporated in the biopolymer matrix polyphenols, exhibited dual role on the hydrogel performance by providing: 1) structural integrity by crosslinking the biopolymer chains; 2) bioactive features, through interaction with major chronic wound factors. The multifunctionality of the obtained materials in the treatment of chronic wounds was evaluated by in-vitro and ex-vivo experiments with chronic wound exudates. The hydrogels exhibited beneficial for wound healing properties, such as inhibitory activity against deleterious wound enzymes and antioxidant activity, and antibacterial activity coupled with biocompatibility to human skin cells.Las heridas crónicas representan un perjuicio económico significativo para los servicios sanitarios del mundo entero, el cual se ve magnificado con el incremento de la población de la tercera edad, que es el grupo que presenta mayor riesgo de desarrollarlas. Las heridas crónicas son una ¿epidemia silenciosa¿ que afecta a una parte muy importante de la población y que suele estar asociada a otras patologías. Las estadísticas reflejan que el 1-2% de la población de los países desarrollados sufrirá este tipo de heridas durante su vida. Los tratamientos actuales están basados en una combinación de estrategias dirigidas a erradicar la cronicidad de la herida y activar los resortes bioquímicos para su sanación mediante el proceso habitual. A este respecto, los apósitos para heridas están ampliamente reconocidos como una parte integral de las terapias de curación de heridas. El cuidado de las heridas viene desde tiempos remotos con el uso de vendajes por parte de los antiguos egipcios. Actualmente el mercado está dominado por apósitos que actúan como barrera física que a su vez controla la humedad de la herida ya sea por absorción del exceso de exudado o por proveer la humedad necesaria. Sin embargo, la naturaleza multifactorial de las heridas crónicas hace que esta estrategia resulte en diversas ocasiones poco o nada efectiva, agravando la situación del paciente. Por lo tanto, es necesario mejorar el tratamiento desarrollando apósitos que sean bioactivos. Estos nuevos apósitos deben, además de proteger la herida y controlar su humedad, interactuar con diversos factores negativos presentes en las heridas modulando su bioactividad en favor de una curación más rápida y eficaz. Materiales con inherentes propiedades curativas son realmente necesarios y este creciente interés ha llevado a la comunidad científica a diseñar apósitos para heridas con mejores propiedades. Sin embargo, a pesar de la multitud de nuevos apósitos desarrollados, no se ha presentado un apósito universal con múltiples propiedades capaz de hacer frente a la mayoría de los factores que provocan la cronicidad de estas úlceras. La falta de este tipo de apósito en el mercado conlleva un gasto económico muy importante para los servicios de salud y representa una parte significativa de sus presupuestos. El desarrollo de un apósito multifuncional y universal aplicable a varios tipos de heridas crónicas implicaría una reducción drástica de los costes de los servicios sanitarios y mejorar la calidad de vida del paciente. En esta tesis se desarrollan materiales multifuncionales basados en hidrogeles biopoliméricos con el objetivo de generar plataformas bioactivas con propiedades óptimas para el tratamiento de heridas crónicas. La formación de estos hidrogeles se basa en una reacción enzimática respetuosa con el Medio Ambiente. El quitosano es un biopolímero intrínsecamente bioactivo que una vez funcionalizado con grupos tiol y reticulado con diferentes polifenoles constituye la estructura del hidrogel. Estos polifenoles confieren dos propiedades al hidrogel: 1) integridad estructural por la reticulación de las cadenas de quitosano; 2) bioactividad, a través de su interacción con la mayoría de factores y patógenos presentes en las heridas crónicas. La multifuncionalidad de los materiales obtenidos para el tratamiento de heridas crónicas ha sido evaluada tanto in vitro como ex vivo con exudados de heridas crónicas. Los hidrogeles desarrollados en esta tesis muestran múltiples propiedades añadidas a las de los apósitos que actualmente hay en el mercado, y entre ellas destacan una elevada actividad antibacteriana, inhibición de enzimas perjudiciales y efecto antioxidante a la vez que presentan gran biocompatibilidad con células de piel humana.Postprint (published version

L’Office des Nations Unies contre la drogue et le crime et la lutte internationale contre la corruption : perceptions des professionnels

Travail dirigé présenté à la Faculté des études supérieures et postdoctorales en vue de l’obtention du grade de Maître ès sciences (M.Sc) en Criminologie – Option sécurité intérieureOutre les changements sociaux associés à la fin du communisme, les années 1990 marquent également une augmentation de l’intérêt à l’égard de la corruption et de ses effets néfastes sur le développement. En raison de la pression exercée par les États-Unis et l’augmentation de la visibilité de la corruption, plusieurs organisations internationales ont vu l’intérêt de s’impliquer dans la lutte anticorruption. La littérature soutient que la Convention des Nations Unies contre la corruption représente le document international anticorruption par excellence. Adopté en 2003, il compte aujourd’hui 144 pays signataires. Cependant, et malgré l’importance du document, les perceptions des professionnels demeurent cachées derrière les discours institutionnels. Par conséquent, cette étude de cas se concentre sur les perceptions des employés travaillant au sein de la Branche de corruption et crime économique de l’ONUDC. Ils révèlent plusieurs difficultés techniques reliées à leur travail. Entre autres, les professionnels évoquent la charge de travail, les moyens financiers et la considération de leur jugement lors du processus d’évaluation. Leurs fonctions sont également limitées par des défis associés à la mise en oeuvre de la convention : l’absence de sanctions directes pour les pays non conformes, l’accès aux données, l’application de la Convention et la différence entre le travail dans les quartiers généraux et le travail sur le terrain. Enfin, les professionnels évoquent certains enjeux caractérisant la coopération sur la lutte anticorruption et l’assistance technique offerte aux États membres.In addition to the social changes associated with the end of communism, the 1990s also marked a growing interest in corruption and its harmful effects on development. Due to pressure from the United States and the increasing visibility of corruption, several international organizations have seen the interest to get involved in the fight against corruption. Nevertheless, the literature supports that the United Nations Convention against Corruption represents the quintessential anti-corruption international document. Adopted in 2003, it now has 144 signatories. Despite the importance of the document, professionals’ perceptions remain hidden behind the institutional discourse. Therefore, this case study focuses on the perceptions of the employees working in the UNODC’s Corruption and Economic Crime Branch. They reveal several technical difficulties related to their work. Among others, professionals evoke workload, financial resources and consideration of their judgments during the evaluation process. Their functions are also limited by challenges associated with the implementation of the Convention: the absence of surveillance and sanctions mechanisms for non compliant countries, the access to data, the application of the Convention and the difference between working in the headquarters and working on the field. The professionals also mention some issues characterizing anticorruption international cooperation and the technical assistance provided to Member States

Multifunctional enzymatically generated hydrogels for chronic wound application

The healing of chronic wounds requires intensive medical intervention at huge healthcare costs. Dressing materials should consider the multifactorial nature of these wounds comprising deleterious proteolytic and oxidative enzymes and high bacterial load. In this work, multifunctional hydrogels for chronic wound application were produced by enzymatic cross- linking of thiolated chitosan and gallic acid. The hydrogels combine several beneficial to wound healing properties, controlling the matrix metalloproteinases (MMPs) and myeloperoxidase (MPO) activities, oxidative stress, and bacterial contamination. In vitro studies revealed above 90% antioxidant activity, and MPO and collagenase inhibition by up to 98 and 23%, respectively. Ex vivo studies with venous leg ulcer exudates confirmed the inhibitory capacity of the dressings against MPO and MMPs. Additionally, the hydrogels reduced the population of the most frequently encountered in nonhealing wounds bacterial strains. The stable at physiological conditions and resistant to lysozyme degradation hydrogels showed high biocompatibility with human skin fibroblastsPeer ReviewedPostprint (author's final draft

Silver Nanoparticles as Multi-Functional Drug Delivery Systems

Nanoparticles can surmount some essential problems of conventional small molecules or biomacromolecules (e.g., DNA, RNA, and protein) used in some diseases by allowing targeted delivery and overcome through biological barriers. Recently, silver nanoparticles have been harnessed as delivery vehicles for therapeutic agents, including antisense oligonucleotides, and other small molecules. Silver is the most profit-oriented precious metal used in the preparation of nanoparticles and nanomaterials because of its antibacterial, antiviral, antifungal, antioxidant and unusually enhanced physicochemical properties compared to the bulk material such as optical, thermal, electrical, and catalytic properties. Small silver nanoparticles offer many advantages as drug carriers, including adjustable size and shape, enhanced stability of surface-bound nucleic acids, high-density surface ligand attachment, transmembrane delivery without harsh transfection agents, protection of the attached therapeutics from degradation, and potential for improved timed/controlled intracellular drug-delivery. Plant-mediated synthesis of silver nanoparticles is gaining interest due to its inexpensiveness, providing a healthier work environment, and protecting human health leading to lessening waste and safer products. The chapter presents the essential physicochemical characteristics, antibacterial, and anticancer properties which silver nanoparticles obtained by plant-mediated methods possess, and their application as drug-delivery systems with a critical view on the possible toxicity on the human body

Stability study of extemporaneously compounded nitrofurantoin oral suspensions for pediatric patients

Aim: To evaluate the stability of nitrofurantoin suspended in different extemporaneously compounded vehicles after storage at 4°C and at 25°C. To formulate an effective, readily available vehicle that can guarantee extended stability and precise dosing. Materials and methods: Nitrofurantoin was suspended at a concentration of 10 mg/mL in seven different vehicles compounded of different blends of Syrupus simplex, sorbitol 70%, methylcellulose 1%, gummi arabici 1%, gummi xanthani 1%, and sodium carboxymethylcellulose (NaCMC) 1%. Samples of 100 mL of every compounded suspension were stored in dark in graded glass bottles at 4°C and at 25°C. Samples were analyzed at the beginning and every 10 days up to day 30 and every 30 days after. Variations of physical properties such as sedimentation, ease of resuspension, color and odor were evaluated visually and organoleptically. Rheological analysis was also performed in order to determine suspensions’ behavior during storage and dosing. Variations in nitrofurantoin concentration and pH were evaluated with suitable analytical procedure (UV-Vis; HPLC; pH/ORP). Microbiological stability was evaluated via incubation on suitable culture media. Results: To the 30th day, only three of the compounded suspensions exhibited significant physical stability and slight change in taste and odor stored at both temperatures. Two samples stored at 25°C exhibited nitrofurantoin concentration greater than 95% and 4 samples stored at 4°C – concentration greater than 95%. All models showed no microbial growth up to day 30. At 120 days, only three of the compounded suspensions, stored at 4°C, exhibited relatively high nitrofurantoin concentrations: 88.2%, 92%, and 81.1%, respectively. Only one model suspension showed chemical and physical stability (≥95% of the initial concentration) for 102 days. No model suspension remained sterile after 30 days. Conclusions: The suspensions compounded with vehicles of blends of syrups, xanthan, croscarmellose (NaCMC), and sorbitol exhibited low to none sedimentation, good uniformity of content and are suitable organoleptically for pediatric administration. The model suspension stored at 4°C (NTF VII 4°C – with major excipients: sucrose 16%, sorbitol 17%, xanthan gum 0.25%, NaCMC 0.25%) stands out with nitrofurantoin concentration higher than 95% along with no or little signs of sedimentation. After adding a suitable preservative agent or system, a formulation with these characteristics might have an expiration date of at least 90 days

Multifunctional enzymatically-generated hydrogel platforms for chronic wound application

Chronic wounds became burdensome problem of worldwide healthcare systems, along with the increased elderly population, which is the most vulnerable risk group, predisposed to their development. Chronic wounds represent a “silent epidemic” that affect a large fraction of the population and are often regarded as a comorbid condition. Statistical surveys indicated that 1-2 % of the population in developed countries will suffer from chronic wounds during their lifetime. Contemporary clinical treatment involves a combination of techniques and procedures aiming at eradication of wound chronicity and switching the biochemical entities to normal wound healing. In this regard, wound dressings have been affirmed and widely accepted as integral part of wound healing therapies. Wound care, by using dressings dates from ancient times, when for instance ancient egyptians applied and arranged bandages. Nowadays, the market is dominated by dressings, which only function besides a simple physical barrier is to balance the wound moisture by either absorbing excess exudates or providing moisture environment. However, the multifactorial nature of chronic wounds often renders this single-factor directed therapy as low or non-effective, aggravating the patient outcome. Thus, the demands for expanding the treatment options to more effective therapy brought about the development of bioactive dressings. These dressings should not only protect the wound and control the wound moisture, but also interact with various adverse wound constituents, modulating their bio-activities in favor of healing. Materials with inherent wound healing features are highly desireable and more attention to such materials among the research communities has lead to the design of wound dressings with improved characteristics. However, amongst the myriad novel dressings synthesized, there is still lack of universal dressing with a panel of features able to address most of the devastating chronic wound constituents. The lack of such on-market dressing, lead to huge economical burden of the healthcare systems, holding significant part of their budgets. Development of universal multifunctional dressing, appropriate for management of many types of chronic wounds will boost the health systems to minimize the costs and improve the quality of patient’s life. This thesis develops multifunctional biopolymer-based hydrogel materials as a bioactive platform with appropriate exploitation characteristics for treatment of chronic wound. To this end, hydrogels were developed by using environmentally benign approach, based on enzymatic reactions. Intrinsically bioactive biopolymer chitosan which served as a matrix, was modified with thiol groups and further in situ enzymatically crosslinked with two different natural polyphenols. The incorporated in the biopolymer matrix polyphenols, exhibited dual role on the hydrogel performance by providing: 1) structural integrity by crosslinking the biopolymer chains; 2) bioactive features, through interaction with major chronic wound factors. The multifunctionality of the obtained materials in the treatment of chronic wounds was evaluated by in-vitro and ex-vivo experiments with chronic wound exudates. The hydrogels exhibited beneficial for wound healing properties, such as inhibitory activity against deleterious wound enzymes and antioxidant activity, and antibacterial activity coupled with biocompatibility to human skin cells.Las heridas crónicas representan un perjuicio económico significativo para los servicios sanitarios del mundo entero, el cual se ve magnificado con el incremento de la población de la tercera edad, que es el grupo que presenta mayor riesgo de desarrollarlas. Las heridas crónicas son una ¿epidemia silenciosa¿ que afecta a una parte muy importante de la población y que suele estar asociada a otras patologías. Las estadísticas reflejan que el 1-2% de la población de los países desarrollados sufrirá este tipo de heridas durante su vida. Los tratamientos actuales están basados en una combinación de estrategias dirigidas a erradicar la cronicidad de la herida y activar los resortes bioquímicos para su sanación mediante el proceso habitual. A este respecto, los apósitos para heridas están ampliamente reconocidos como una parte integral de las terapias de curación de heridas. El cuidado de las heridas viene desde tiempos remotos con el uso de vendajes por parte de los antiguos egipcios. Actualmente el mercado está dominado por apósitos que actúan como barrera física que a su vez controla la humedad de la herida ya sea por absorción del exceso de exudado o por proveer la humedad necesaria. Sin embargo, la naturaleza multifactorial de las heridas crónicas hace que esta estrategia resulte en diversas ocasiones poco o nada efectiva, agravando la situación del paciente. Por lo tanto, es necesario mejorar el tratamiento desarrollando apósitos que sean bioactivos. Estos nuevos apósitos deben, además de proteger la herida y controlar su humedad, interactuar con diversos factores negativos presentes en las heridas modulando su bioactividad en favor de una curación más rápida y eficaz. Materiales con inherentes propiedades curativas son realmente necesarios y este creciente interés ha llevado a la comunidad científica a diseñar apósitos para heridas con mejores propiedades. Sin embargo, a pesar de la multitud de nuevos apósitos desarrollados, no se ha presentado un apósito universal con múltiples propiedades capaz de hacer frente a la mayoría de los factores que provocan la cronicidad de estas úlceras. La falta de este tipo de apósito en el mercado conlleva un gasto económico muy importante para los servicios de salud y representa una parte significativa de sus presupuestos. El desarrollo de un apósito multifuncional y universal aplicable a varios tipos de heridas crónicas implicaría una reducción drástica de los costes de los servicios sanitarios y mejorar la calidad de vida del paciente. En esta tesis se desarrollan materiales multifuncionales basados en hidrogeles biopoliméricos con el objetivo de generar plataformas bioactivas con propiedades óptimas para el tratamiento de heridas crónicas. La formación de estos hidrogeles se basa en una reacción enzimática respetuosa con el Medio Ambiente. El quitosano es un biopolímero intrínsecamente bioactivo que una vez funcionalizado con grupos tiol y reticulado con diferentes polifenoles constituye la estructura del hidrogel. Estos polifenoles confieren dos propiedades al hidrogel: 1) integridad estructural por la reticulación de las cadenas de quitosano; 2) bioactividad, a través de su interacción con la mayoría de factores y patógenos presentes en las heridas crónicas. La multifuncionalidad de los materiales obtenidos para el tratamiento de heridas crónicas ha sido evaluada tanto in vitro como ex vivo con exudados de heridas crónicas. Los hidrogeles desarrollados en esta tesis muestran múltiples propiedades añadidas a las de los apósitos que actualmente hay en el mercado, y entre ellas destacan una elevada actividad antibacteriana, inhibición de enzimas perjudiciales y efecto antioxidante a la vez que presentan gran biocompatibilidad con células de piel humana

Multifunctional enzymatically-generated hydrogel platforms for chronic wound application

Chronic wounds became burdensome problem of worldwide healthcare systems, along with the increased elderly population, which is the most vulnerable risk group, predisposed to their development. Chronic wounds represent a “silent epidemic” that affect a large fraction of the population and are often regarded as a comorbid condition. Statistical surveys indicated that 1-2 % of the population in developed countries will suffer from chronic wounds during their lifetime. Contemporary clinical treatment involves a combination of techniques and procedures aiming at eradication of wound chronicity and switching the biochemical entities to normal wound healing. In this regard, wound dressings have been affirmed and widely accepted as integral part of wound healing therapies. Wound care, by using dressings dates from ancient times, when for instance ancient egyptians applied and arranged bandages. Nowadays, the market is dominated by dressings, which only function besides a simple physical barrier is to balance the wound moisture by either absorbing excess exudates or providing moisture environment. However, the multifactorial nature of chronic wounds often renders this single-factor directed therapy as low or non-effective, aggravating the patient outcome. Thus, the demands for expanding the treatment options to more effective therapy brought about the development of bioactive dressings. These dressings should not only protect the wound and control the wound moisture, but also interact with various adverse wound constituents, modulating their bio-activities in favor of healing. Materials with inherent wound healing features are highly desireable and more attention to such materials among the research communities has lead to the design of wound dressings with improved characteristics. However, amongst the myriad novel dressings synthesized, there is still lack of universal dressing with a panel of features able to address most of the devastating chronic wound constituents. The lack of such on-market dressing, lead to huge economical burden of the healthcare systems, holding significant part of their budgets. Development of universal multifunctional dressing, appropriate for management of many types of chronic wounds will boost the health systems to minimize the costs and improve the quality of patient’s life. This thesis develops multifunctional biopolymer-based hydrogel materials as a bioactive platform with appropriate exploitation characteristics for treatment of chronic wound. To this end, hydrogels were developed by using environmentally benign approach, based on enzymatic reactions. Intrinsically bioactive biopolymer chitosan which served as a matrix, was modified with thiol groups and further in situ enzymatically crosslinked with two different natural polyphenols. The incorporated in the biopolymer matrix polyphenols, exhibited dual role on the hydrogel performance by providing: 1) structural integrity by crosslinking the biopolymer chains; 2) bioactive features, through interaction with major chronic wound factors. The multifunctionality of the obtained materials in the treatment of chronic wounds was evaluated by in-vitro and ex-vivo experiments with chronic wound exudates. The hydrogels exhibited beneficial for wound healing properties, such as inhibitory activity against deleterious wound enzymes and antioxidant activity, and antibacterial activity coupled with biocompatibility to human skin cells.Las heridas crónicas representan un perjuicio económico significativo para los servicios sanitarios del mundo entero, el cual se ve magnificado con el incremento de la población de la tercera edad, que es el grupo que presenta mayor riesgo de desarrollarlas. Las heridas crónicas son una ¿epidemia silenciosa¿ que afecta a una parte muy importante de la población y que suele estar asociada a otras patologías. Las estadísticas reflejan que el 1-2% de la población de los países desarrollados sufrirá este tipo de heridas durante su vida. Los tratamientos actuales están basados en una combinación de estrategias dirigidas a erradicar la cronicidad de la herida y activar los resortes bioquímicos para su sanación mediante el proceso habitual. A este respecto, los apósitos para heridas están ampliamente reconocidos como una parte integral de las terapias de curación de heridas. El cuidado de las heridas viene desde tiempos remotos con el uso de vendajes por parte de los antiguos egipcios. Actualmente el mercado está dominado por apósitos que actúan como barrera física que a su vez controla la humedad de la herida ya sea por absorción del exceso de exudado o por proveer la humedad necesaria. Sin embargo, la naturaleza multifactorial de las heridas crónicas hace que esta estrategia resulte en diversas ocasiones poco o nada efectiva, agravando la situación del paciente. Por lo tanto, es necesario mejorar el tratamiento desarrollando apósitos que sean bioactivos. Estos nuevos apósitos deben, además de proteger la herida y controlar su humedad, interactuar con diversos factores negativos presentes en las heridas modulando su bioactividad en favor de una curación más rápida y eficaz. Materiales con inherentes propiedades curativas son realmente necesarios y este creciente interés ha llevado a la comunidad científica a diseñar apósitos para heridas con mejores propiedades. Sin embargo, a pesar de la multitud de nuevos apósitos desarrollados, no se ha presentado un apósito universal con múltiples propiedades capaz de hacer frente a la mayoría de los factores que provocan la cronicidad de estas úlceras. La falta de este tipo de apósito en el mercado conlleva un gasto económico muy importante para los servicios de salud y representa una parte significativa de sus presupuestos. El desarrollo de un apósito multifuncional y universal aplicable a varios tipos de heridas crónicas implicaría una reducción drástica de los costes de los servicios sanitarios y mejorar la calidad de vida del paciente. En esta tesis se desarrollan materiales multifuncionales basados en hidrogeles biopoliméricos con el objetivo de generar plataformas bioactivas con propiedades óptimas para el tratamiento de heridas crónicas. La formación de estos hidrogeles se basa en una reacción enzimática respetuosa con el Medio Ambiente. El quitosano es un biopolímero intrínsecamente bioactivo que una vez funcionalizado con grupos tiol y reticulado con diferentes polifenoles constituye la estructura del hidrogel. Estos polifenoles confieren dos propiedades al hidrogel: 1) integridad estructural por la reticulación de las cadenas de quitosano; 2) bioactividad, a través de su interacción con la mayoría de factores y patógenos presentes en las heridas crónicas. La multifuncionalidad de los materiales obtenidos para el tratamiento de heridas crónicas ha sido evaluada tanto in vitro como ex vivo con exudados de heridas crónicas. Los hidrogeles desarrollados en esta tesis muestran múltiples propiedades añadidas a las de los apósitos que actualmente hay en el mercado, y entre ellas destacan una elevada actividad antibacteriana, inhibición de enzimas perjudiciales y efecto antioxidante a la vez que presentan gran biocompatibilidad con células de piel humana

Multifunctional enzymatically-generated hydrogel platforms for chronic wound application

Tesi per compendi d'articles, amb dues seccions retallades per drets de l'editorChronic wounds became burdensome problem of worldwide healthcare systems, along with the increased elderly population, which is the most vulnerable risk group, predisposed to their development. Chronic wounds represent a “silent epidemic” that affect a large fraction of the population and are often regarded as a comorbid condition. Statistical surveys indicated that 1-2 % of the population in developed countries will suffer from chronic wounds during their lifetime. Contemporary clinical treatment involves a combination of techniques and procedures aiming at eradication of wound chronicity and switching the biochemical entities to normal wound healing. In this regard, wound dressings have been affirmed and widely accepted as integral part of wound healing therapies. Wound care, by using dressings dates from ancient times, when for instance ancient egyptians applied and arranged bandages. Nowadays, the market is dominated by dressings, which only function besides a simple physical barrier is to balance the wound moisture by either absorbing excess exudates or providing moisture environment. However, the multifactorial nature of chronic wounds often renders this single-factor directed therapy as low or non-effective, aggravating the patient outcome. Thus, the demands for expanding the treatment options to more effective therapy brought about the development of bioactive dressings. These dressings should not only protect the wound and control the wound moisture, but also interact with various adverse wound constituents, modulating their bio-activities in favor of healing. Materials with inherent wound healing features are highly desireable and more attention to such materials among the research communities has lead to the design of wound dressings with improved characteristics. However, amongst the myriad novel dressings synthesized, there is still lack of universal dressing with a panel of features able to address most of the devastating chronic wound constituents. The lack of such on-market dressing, lead to huge economical burden of the healthcare systems, holding significant part of their budgets. Development of universal multifunctional dressing, appropriate for management of many types of chronic wounds will boost the health systems to minimize the costs and improve the quality of patient’s life. This thesis develops multifunctional biopolymer-based hydrogel materials as a bioactive platform with appropriate exploitation characteristics for treatment of chronic wound. To this end, hydrogels were developed by using environmentally benign approach, based on enzymatic reactions. Intrinsically bioactive biopolymer chitosan which served as a matrix, was modified with thiol groups and further in situ enzymatically crosslinked with two different natural polyphenols. The incorporated in the biopolymer matrix polyphenols, exhibited dual role on the hydrogel performance by providing: 1) structural integrity by crosslinking the biopolymer chains; 2) bioactive features, through interaction with major chronic wound factors. The multifunctionality of the obtained materials in the treatment of chronic wounds was evaluated by in-vitro and ex-vivo experiments with chronic wound exudates. The hydrogels exhibited beneficial for wound healing properties, such as inhibitory activity against deleterious wound enzymes and antioxidant activity, and antibacterial activity coupled with biocompatibility to human skin cells.Las heridas crónicas representan un perjuicio económico significativo para los servicios sanitarios del mundo entero, el cual se ve magnificado con el incremento de la población de la tercera edad, que es el grupo que presenta mayor riesgo de desarrollarlas. Las heridas crónicas son una ¿epidemia silenciosa¿ que afecta a una parte muy importante de la población y que suele estar asociada a otras patologías. Las estadísticas reflejan que el 1-2% de la población de los países desarrollados sufrirá este tipo de heridas durante su vida. Los tratamientos actuales están basados en una combinación de estrategias dirigidas a erradicar la cronicidad de la herida y activar los resortes bioquímicos para su sanación mediante el proceso habitual. A este respecto, los apósitos para heridas están ampliamente reconocidos como una parte integral de las terapias de curación de heridas. El cuidado de las heridas viene desde tiempos remotos con el uso de vendajes por parte de los antiguos egipcios. Actualmente el mercado está dominado por apósitos que actúan como barrera física que a su vez controla la humedad de la herida ya sea por absorción del exceso de exudado o por proveer la humedad necesaria. Sin embargo, la naturaleza multifactorial de las heridas crónicas hace que esta estrategia resulte en diversas ocasiones poco o nada efectiva, agravando la situación del paciente. Por lo tanto, es necesario mejorar el tratamiento desarrollando apósitos que sean bioactivos. Estos nuevos apósitos deben, además de proteger la herida y controlar su humedad, interactuar con diversos factores negativos presentes en las heridas modulando su bioactividad en favor de una curación más rápida y eficaz. Materiales con inherentes propiedades curativas son realmente necesarios y este creciente interés ha llevado a la comunidad científica a diseñar apósitos para heridas con mejores propiedades. Sin embargo, a pesar de la multitud de nuevos apósitos desarrollados, no se ha presentado un apósito universal con múltiples propiedades capaz de hacer frente a la mayoría de los factores que provocan la cronicidad de estas úlceras. La falta de este tipo de apósito en el mercado conlleva un gasto económico muy importante para los servicios de salud y representa una parte significativa de sus presupuestos. El desarrollo de un apósito multifuncional y universal aplicable a varios tipos de heridas crónicas implicaría una reducción drástica de los costes de los servicios sanitarios y mejorar la calidad de vida del paciente. En esta tesis se desarrollan materiales multifuncionales basados en hidrogeles biopoliméricos con el objetivo de generar plataformas bioactivas con propiedades óptimas para el tratamiento de heridas crónicas. La formación de estos hidrogeles se basa en una reacción enzimática respetuosa con el Medio Ambiente. El quitosano es un biopolímero intrínsecamente bioactivo que una vez funcionalizado con grupos tiol y reticulado con diferentes polifenoles constituye la estructura del hidrogel. Estos polifenoles confieren dos propiedades al hidrogel: 1) integridad estructural por la reticulación de las cadenas de quitosano; 2) bioactividad, a través de su interacción con la mayoría de factores y patógenos presentes en las heridas crónicas. La multifuncionalidad de los materiales obtenidos para el tratamiento de heridas crónicas ha sido evaluada tanto in vitro como ex vivo con exudados de heridas crónicas. Los hidrogeles desarrollados en esta tesis muestran múltiples propiedades añadidas a las de los apósitos que actualmente hay en el mercado, y entre ellas destacan una elevada actividad antibacteriana, inhibición de enzimas perjudiciales y efecto antioxidante a la vez que presentan gran biocompatibilidad con células de piel humana

Glucagon- and insulin-immunopositive endocrine cells in porcine extrahepatic bile ducts and gallbladder

IntroductionPancreatic β-cells and α-cells have been found in the murine extrahepatic biliary ducts but not in the gallbladder. However, there has been no information reported in the specialized literature about the presence of glucagon- and insulin-expressing endocrine cells in porcine bile ducts and gallbladder.AimWe aimed to perform an immunohistochemical study to identify glucagon- and insulin-positive cells and their distribution in the porcine extrahepatic biliary ducts and gallbladder.MethodThe immunohistochemical method was used to detect the presence and distribution of glucagon- and insulin-positive endocrine cells in the common hepatic duct (ductus hepaticus communis), common bile duct (ductus choledochus), cystic duct (ductus cysticus), and gallbladder (vesica fellea) of male pigs. Chromogranin A was used as a typical marker for endocrine cells.ResultsThe density of chromogranin A-, glucagon- and insulin-positive cells per field was the largest in the common bile duct, followed by the common hepatic duct, cystic duct, and gallbladder. The three types of endocrine cells showed specific localization in the superficial and deep glands of the studied organs.Conclusion and clinical importanceThe distribution of glucagon- and insulin-immunopositive endocrine cells in the porcine extrahepatic biliary tract was established for the first time as a new source of these hormones. The presence of α- and β-cells in the epithelium of extrahepatic bile ducts can be applied in treatment of diabetes, taking into account the possibility to reprogram the biliary epithelium to mentioned pancreatic endocrine cell types

Biomedical textiles

The use of textiles in medicine dates back to ancient times. In modern medicine, textile fibers can be found in a wide variety of biomedical devices from simple non-woven bandages for wounds to complex hollow fiber membranes in artificial lungs. The combination of biotechnology and textile engineering could improve the performance of biomedical textiles or produce novel textile components for biomedical devices. This chapter overviews the recent progress of enzyme biotechnology for biomedical textiles in three different aspects: i) enzymes as tools for fiber functionalization, ii) enzymes immobilized on textiles carriers for therapeutic or bioanalytical application, and iii) enzymatically responsive textiles. Innovative technologies for upgrading the functional properties of biomedical textiles are also considered.Postprint (author's final draft