1,721,156 research outputs found
Polylactide biodegradable scaffolds for tissue engineering applications phase separation-based techniques
No full textOne of the most reliable techniques for the preparation of biodegradable scaffoldssuitable for tissue engineering applications (e.g. regeneration of wounded/damagedtissues) is based on liquid/liquid phase separation of ternary solvent/antisolvent/polymersolutions. In particular, two phase separation protocols are examined here: ThermallyInduced Phase Separation (TIPS) and Diffusion Induces Phase Separation (DIPS). According to the former protocol, a thermodynamically stable polymeric ternarysolution is brought below its metastability/instability point (spinodal/binodal curve) byquench in a cooling medium: under opportune conditions, a foam-like structure is formedby nucleation and 3-D growth of the polymer lean phase, which, after solvent removal byrinsing and drying, will constitute the voids of the as-generated "open-pore" architecture. Two ternary polymeric solutions were examined in detail: Poly-L-Lactic Acid(PLLA)/Dioxane (solvent)/TetrahydroFurane (THF, antisolvent) andPLLA/Dioxane/Water (antisolvent). For both systems (PLLA/Dioxane/THF andPLLA/Dioxane/Water) the solvent (dioxane) to antisolvent (THF or water) ratio and thepolymer concentration were varied; moreover, different cooling paths from the stableternary solution down to the instable zone were examined.In order to tune the biodegradation kinetics of the foams, PLLA/PLA blends invarious proportions were dissolved in the dioxane/water system. As for the latter phase separation protocol, vessel-shape PLLA (and PLLA/PLAblends) scaffolds for vascular tissue engineering applications were produced byperforming a dip-coating around a nylon fibre, followed by a Diffusion Induced PhaseSeparation (DIPS) step, where samples were pool immersed in a bath containing solventand antisolvent in different proportions, thus inducing phase separation by changing thesolvent power.Structure and morphology of the resulting foams were characterized by apparentporosity, Scanning Electron Microscopy (SEM), gas/liquid porometry, calorimetricanalysis (Differential Scanning Calorimetry, DSC), Wide Angle X-ray Diffractometry(WAXD), Optical Microscopy (OM), Confocal Laser Microscopy. Biodegradationkinetics was studied by monitoring weight loss on a dry basis with time under differentenvironmental conditions. © 2011 by Nova Science Publishers, Inc
Isolation of adult rat cardiomyocytes using recombinant collagenases
No full textDirect isolation of primary cells from tissues and organs allows for the maintenance of important cell characteristics and properties for in vitro studies and a plethora of biomedical applications. Dissociation of cells from the organ of interest is possible due to the enzymatic activity of collagenases. The choice and the dose of these enzymes is the critical step to obtain the maximum number of cells with intact structure and function. In this contest, Abiel collagenases class I (Col G) and class II (Col H) were synthesised using recombinant DNA technologies and their ability to degrade collagen in cell isolation from different tissues was tested. Examples of cells isolated with these enzymes include Langerhans islets, hepatocytes, chondrocytes, osteoblasts, fibroblasts, and stem and retinal cells that be used for in vitro studies. In this contest, primary cardiomyocytes represent a perfect murine model to investigate numerous heart diseases. Herein, a protocol of cardiomyocyte extraction from rat heart, using a combination of Abiel collagenases supplemented with thermolysin protease, is proposed. The structure and the viability of isolated cells were tested over time by optical and fluorescence microscopy and viability assays. Further cellular structure characterisation was performed by western blot analysis, using specific cardiomyocytes markers. Isolation of viable primary heart cells with unaltered properties and functionality can potentially provide in vitro models to study heart function, arrhythmias, long Q-T syndrome and cardiotoxicity
Recovery of Bioactive Compounds from Marine Organisms: Focus on the Future Perspectives for Pharmacological, Biomedical and Regenerative Medicine Applications of Marine Collagen
Full text linkMarine environments cover more than 70% of the Earth's surface and are among the richest and most complex ecosystems. In terms of biodiversity, the ocean represents an important source, still not widely exploited, of bioactive products derived from species of bacteria, plants, and animals. However, global warming, in combination with multiple anthropogenic practices, represents a serious environmental problem that has led to an increase in gelatinous zooplankton, a phenomenon referred to as jellyfish bloom. In recent years, the idea of "sustainable development" has emerged as one of the essential elements of green-economy initiatives; therefore, the marine environment has been re-evaluated and considered an important biological resource. Several bioactive compounds of marine origin are being studied, and among these, marine collagen represents one of the most attractive bio-resources, given its use in various disciplines, such as clinical applications, cosmetics, the food sector, and many other industrial applications. This review aims to provide a current overview of marine collagen applications in the pharmacological and biomedical fields, regenerative medicine, and cell therapy
The Multifaced Role of Collagen in Cancer Development and Progression
Full text linkCollagen is a crucial protein in the extracellular matrix (ECM) essential for preserving tissue architecture and supporting crucial cellular functions like proliferation and differentiation. There are twenty-eight identified types of collagen, which are further divided into different subgroups. This protein plays a critical role in regulating tissue homeostasis. However, in solid tumors, the balance can be disrupted, due to an abundance of collagen in the tumor microenvironment, which significantly affects tumor growth, cell invasion, and metastasis. It is important to investigate the specific types of collagens in cancer ECM and their distinct roles in tumor progression to comprehend their unique contribution to tumor behavior. The diverse pathophysiological functions of different collagen types in cancers illustrate collagen's dual roles, offering potential therapeutic options and serving as prognostic markers
Vibrio proteases for biomedical applications: Modulating the proteolytic secretome of v. alginolyticus and v. parahaemolyticus for improved enzymes production
Full text linkProteolytic enzymes are of great interest for biotechnological purposes, and their large-scale production, as well as the discovery of strains producing new molecules, is a relevant issue. Collagenases are employed for biomedical and pharmaceutical purposes. The high specificity of collagenase-based preparations toward the substrate strongly relies on the enzyme purity. However, the overall activity may depend on the cooperation with other proteases, the presence of which may be essential for the overall enzymatic activity, but potentially harmful for cells and tissues. Vibrios produce some of the most promising bacterial proteases (including collagenases), and their exo-proteome includes several enzymes with different substrate specificities, the production and relative abundances of which strongly depend on growth conditions. We evaluated the effects of different media compositions on the proteolytic exo-proteome of Vibrio alginolyticus and its closely relative Vibrio parahaemolyticus, in order to improve the overall proteases production, as well as the yield of the desired enzymes subset. Substantial biological responses were achieved with all media, which allowed defining culture conditions for targeted improvement of selected enzyme classes, besides giving insights in possible regulatory mechanisms. In particular, we focused our efforts on collagenases production, because of the growing biotechnological interest due to their pharmaceutical/biomedical applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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