In vitro assessment of the enzymatic degradation of several starch based biomaterials

The susceptibility of starch-based biomaterials to enzymatic degradation by amylolytic enzymes (glucoamylase and α-amylase) was investigated by means of incubating the materials with a buffer solution, containing enzymes at different concentrations and combinations, at 37 °C for 6 weeks. Two polymeric blends of corn starch with poly(ethylene-vinyl alcohol) copolymer and poly(Є-caprolactone), designated by SEVA-C and SPCL, respectively, were studied. The material degradation was characterized by gravimetry measurements, tensile mechanical testing, scanning electron microscopy (SEM), and Fourrier transform infrared-attenuated total reflectance (FTIR-ATR). The degradation liquors were analyzed for determination of reducing sugars, as a result of enzyme activity, and high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was used to identify the degradation products. All of the analysis performed showed that starch polymeric blends are susceptible to enzymatic degradation, as detected by increased weight loss and reducing sugars in solution. α-Amylase caused significant changes on the overall mechanical properties of the materials, with a decrease of about 65% and 58% being observed in the moduli for SEVA-C and SPCL, respectively, when compared with the control (samples incubated in buffer only). SEM analysis detected the presence of fractures and pores at the material’s surface as a result of starch degradation by amylolytic enzymes. FTIR spectra confirmed a decrease on the band corresponding to glycosidic linkage (-C-O-C-) of starch after incubation of the materials with α-amylase. In contrast, the incubation of the polymers in buffer only, did not cause significant changes on the material’s properties and morphology. Comparing the two materials, SEVA-C exhibited a higher degradability, which is related to the physicochemical structure of the materials and also to the fact that the starch concentration is higher in SEVA-C. The identification of the degradation products by HPAEC-PAD revealed that glucose was the major product of the enzymatic degradation of starch-based polymers. α-Amylase, as expected, is the key enzyme involved in the starch degradation, contributing to major changes on the physicochemical properties of the materials. Nevertheless, it was also found that starch-based polymers can also be degraded by other amylolytic enzymes but in a smaller extent.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/5744/2001 - Programa Operacional "Ciência, Tecnologia, Inovação (POCTI ) - União Europeia. Fundo Europeu de Desenvolvimento Regional (FEDER)

Notas sobre a biologia de Centrolabrus caeruleus Azevedo, 1999 (Teleostei: Labridae)

Centrolabrus caeruleus is a recently described littoral fish whose biology is poorly known, despite the fact that it is very abundant in the Azores. This paper presents general information about the age and growth, food and reproduction of this species. Males grow to larger sizes than females, and there are sexual differences in colour and behaviour. Preliminary von Bertalanffy growth curves are given for both sexes, based on modal analysis of the monthly length-frequency distributions. The length-weight relationship is also given. Food is dominated by small phytal invertebrates. Reproduction occurs mainly between March and June. Young of the year are seen from July on. Territorial males build algal nests where females spawn. Details of nest building, and of the courtship and spawning behaviours are given

Incorporation of proteins and enzymes at different stages of the preparation of calcium phosphate coatings on a degradable substrate by a biomimetic methodology

In this work, the possibility of incorporating proteins into calcium phosphate (Ca-P) coatings, prepared on the surface of starch polymeric biomaterials by means of a biomimetic route, was investigated. The morphology, chemical composition and crystallinity of Ca-P coatings was assessed and related to the incorporation of the studied biomolecules. For that, bovine serum albumin (BSA) and aamylase were added in concentrations of 1 mg/ml to simulated body fluid (SBF) solutions, being both added at the nucleation or growth stages of the biomimetic coating process. A biodegradable blend of corn starch/ethylene vinyl alcohol (SEVA-C) was used as substrate and bioactive glass (45S5 BioglassR) was used as the nucleating agent. The obtained Ca-P coatings were characterised by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy using an attenuated reflectance device (FTIR-ATR) and thin-film X-ray diffraction (TF-XRD). Additionally, to evaluate the activity of the incorporated enzyme and the stability of the Ca-P films, coated samples were immersed in an SBF solution for different periods of time. The enzyme activity was measured and the morphology of the coating examined by SEM. The results obtained showed that the presence of protein molecules, at the nucleation or growth stages, lead to the formation of a dense Ca-P film presenting different morphologies that were different of the selected coating conditions. FTIR-ATR analysis detected the presence of carbonate and phosphate groups on the Ca-P layer, indicating the formation of a coating similar to the mineral component of vertebrates bone tissue. When proteins were added, amide I and amide II bands, characteristic groups of protein molecules, were also detected, revealing the efficient incorporation of these biomolecules into the Ca-P coatings. Ca-P coatings, with a-amylase incorporated at the nucleation stage, showed no degradation of the film after incubation in SBF for 28 days. The release of increasing concentration of reducing sugars with degradation time revealed that a-amylase was efficiently incorporated in the coating remaining active throughout the coating preparation. This can be a strategy that will allow, in addition of conferring osteoconductive properties to biodegradable polymers, also simultaneously tailoring their degradation kinetics.Fundação para a Ciência e a Tecnologia (FCT

Highly porous and interconnected starch-based scaffolds : production, characterization and surface modification

A convenient and straightforward process for preparation of highly porous and interconnected !ber mesh scaffolds with 50 wt.% content of starch is described. The proposed methodology avoids some of the previous encountered problems associated with the processing of starch-based materials such as thermal degradation, starch entrapment in the material bulk and inability to control/minimise the thickness of the !bers obtained by melt spinning, or low porosity and lack of interconnectivity for the scaffolds obtained by extrusion or injection moulding with blowing agent. Topographical characterisation of the obtained !bers revealed rough surface commonly related with increased cell attachment and growth. The in vitro tests with osteoblast cell line con!rmed this trend and we observed higher cell number with increasing of the culture time. These results were also associated with protein adsorption from a complex solution where predominant adsorption of vitronectin over !bronectin was detected. Finally, a model modi!cation by plasma was also carried out in order to con!rm the versatility of these scaffolds by the possibility to further upgrade them via surface functionalisation. The in vitro tests con!rmed that osteoblast-like cells proliferate faster on the modi!ed scaffolds, which allows shortening the time needed for culturing prior to implantation.This work was partially supported by the European NoE EXPER-TISSUES (NMP3-CT-2004-500283), EU Marie Curie Actions, Alea Jacta Est (MEST-CT-2004-008104) and FCT project PTDC/CTM/67560/2006. The authors would also like to acknowledge Sofia G. Caridade and Dr Marina I. Santos for their excellent technical assistance with the DMA and confocal microscopy, respectively

Effects of protein incorporation on calcium phosphate coating

The incorporation of proteins into calcium phosphate (Ca–P) coatings is expected to alter their properties. The aim of this work is, therefore, to study the effect of protein concentration on the formation of Ca–P film. A biodegradable blend of corn starch/ethylene vinyl alcohol (SEVA-C) was used as substrate and bioactive glass (45S5 Bioglass®) was used as a nucleating agent. Bovine serum albumin (BSA) and α-amylase were added, separately, at a concentration of 0.5, 1, and 5 mg/mLto simulated body fluid (SBF) solutions, at the nucleation stage. The incorporation of protein molecules was shown to affect the properties of Ca–P coatings in terms of morphology, composition and crystallinity. Both proteins seem to inhibit in some extent and/or retard the growth of Ca–P nuclei at 0.5 and 5 mg/mL concentrations. FTIR analyses revealed the presence of phosphate and carbonate groups, confiming the formation of a Ca–P layer. The characteristic groups of protein molecules were also detected on the IR spectra, which indicate the efficient incorporation of the proteins into the coatings. When α-amylase was added to the SBF solution the production of reducing sugars was detected, proving the retention of enzyme activity. These results suggest the carrier potential of Ca–P coatings for the sustained delivery of other biologically active proteins and consequently with a strong potential for inducing bone tissue regeneration.This work was partially supported by Portuguese Foundation for Science and Technology (FCT) and was performed within the framework of the project BIOLEARN (POCTI/CTM/38803/2001) through funds from the POCH and/or FEDER Programmes. 1. B. Leonor thanks FCT for providing her a PhD scholarship (SFRH/BD/9031/2002)

A Pipeline for Clustering by Compression with Application to Patient Stratification in Spondyloarthritis

Funding Information: The authors acknowledge Fundação para a Ciência e Tecnologia, LASIGE Research Unit, ref. UIDB/00408/2020 and ref. UIDP/00408/2020 and Instituto de Telecomunicações Research Unit, ref. UIDB/50008/2020, and UIDP/50008/2020. The authors also acknowledge the Project PREDICT (PTDC/CCI-CIF/29877/2017), funded by Fundo Europeu de Desenvolvimento Regional (FEDER), through Programa Operacional Regional LISBOA (LISBOA2020), and by national funds, through Fundacção para a Ciência e Tecnologia (FCT), and projects MATISSE (DSAIPA/DS/0026/2019), MONET (PTDC/CCI-BIO/4180/2020) and SmartGlauco (PTDC/CTM-REF/2679/2020). Publisher Copyright: © 2023 by the authors.The normalized compression distance (NCD) is a similarity measure between a pair of finite objects based on compression. Clustering methods usually use distances (e.g., Euclidean distance, Manhattan distance) to measure the similarity between objects. The NCD is yet another distance with particular characteristics that can be used to build the starting distance matrix for methods such as hierarchical clustering or K-medoids. In this work, we propose Zgli, a novel Python module that enables the user to compute the NCD between files inside a given folder. Inspired by the CompLearn Linux command line tool, this module iterates on it by providing new text file compressors, a new compression-by-column option for tabular data, such as CSV files, and an encoder for small files made up of categorical data. Our results demonstrate that compression by column can yield better results than previous methods in the literature when clustering tabular data. Additionally, the categorical encoder shows that it can augment categorical data, allowing the use of the NCD for new data types. One of the advantages is that using this new feature does not require knowledge or context of the data. Furthermore, the fact that the new proposed module is written in Python, one of the most popular programming languages for machine learning, potentiates its use by developers to tackle problems with a new approach based on compression. This pipeline was tested in clinical data and proved a promising computational strategy by providing patient stratification via clusters aiding in precision medicine.publishersversionpublishe

Social dimension of urban and periurban agriculture

[eng] The introduction of agriculture in cities is one of the current priority axes for urban environmental reform. There is a broad consensus in this regard, largely because of the improvement of urban ecosystem balances. However, urban agriculture also offers various possibilities for society to the extent that it can contribute to solving urban poverty situations, while improving the public health of the neighborhoods where it is located, especially based on ecological principles. In addition to other advantages that directly involve the population that practices agriculture or that has it as a food source. In this way, urban agriculture helps mitigate the double socio-environmental dimension of the planetary ecological crisis of our time. In this sense, this study aims to deepen the social dimension of urban agriculture by problematizing experiences of different cities in the world (particularly Barcelona, Girona and Natal), the latter as contextualization, proposing a scheme of the different types of advantages that it entails. The conclusion points in the direction of a social phenomenon marked by territorial resistance and transition towards a more balanced and counter-rational productive paradigm opposed to the globalized totalitarian capitalist paradigm.[por] A introdução da agricultura nas cidades é um dos eixos prioritários atuais para a reforma ambiental urbana. Existe um amplo consenso a esse respeito, principalmente devido à melhoria do equilíbrio dos ecossistemas urbanos. Ademais, a agricultura urbana também oferece várias possibilidades para a sociedade, na medida em que pode contribuir para a solução de situações de pobreza urbana, além de melhorar a saúde pública dos bairros onde está localizada, principalmente com base em princípios ecológicos. Além de outras vantagens que envolvem diretamente a população que pratica a agricultura ou que a possui como fonte de alimento. Dessa maneira, a agricultura urbana ajuda a mitigar a dupla dimensão socioambiental da crise ecológica planetária de nosso tempo. Nesse sentido, este estudo visa aprofundar a discussão sobre a dimensão social da agricultura urbana, problematizando experiências de diferentes cidades do mundo (particularmente Barcelona, Girona e Natal), esta última a título de contextualização, propondo um esquema dos diferentes tipos de vantagens que essa apresenta. A conclusão aponta na direção de um fenômeno social marcado pela resistência territorial e pela transição para um paradigma produtivo mais equilibrado e contra-racional, em oposição ao paradigma capitalista totalitário globalizado.[spa] La introducción de la agricultura en las ciudades es uno de los ejes prioritarios actuales para la reforma ambiental urbana. Existe un amplio consenso al respecto, principalmente debido al mejor equilibrio de los ecosistemas urbanos. Además, la agricultura urbana también ofrece varias posibilidades para la sociedad, ya que puede contribuir a la solución de situaciones de pobreza urbana, además de mejorar la salud pública de los barrios donde se ubica, principalmente sobre la base de principios ecológicos. Además de otras ventajas que involucran directamente a la población que practica la agricultura o que la tiene como fuente de alimento. De esta forma, la agricultura urbana ayuda a mitigar la doble dimensión socioambiental de la crisis ecológica planetaria de nuestro tiempo. En este sentido, este estudio tiene como objetivo profundizar la discusión sobre la dimensión social de la agricultura urbana, problematizar las experiencias de diferentes ciudades del mundo (particularmente Barcelona, Girona y Natal), esta última a título de contextualización, además de proponer un esquema de los diferentes tipos de ventajas que presenta. La conclusión apunta hacia un fenómeno social marcado por la resistencia territorial y la transición a un paradigma productivo más equilibrado y contrarracional, en oposición al paradigma capitalista totalitario globalizado

Natural origin scaffolds with in situ pore forming capability for bone tissue engineering applications

This work describes the development of a biodegradable matrix, based on chitosan and starch, with the ability to form a porous structure in situ due to the attack by specific enzymes present in the human body (a-amylase and lysozyme). Scaffolds with three different compositions were developed: chitosan (C100) and chitosan/starch (CS80-20, CS60-40). Compressive test results showed that these materials exhibit very promising mechanical properties, namely a high modulus in both the dry and wet states. The compressive modulus in the dry state for C100 was 580 ± 33 MPa, CS80-20 (402 ± 62 MPa) and CS60-40 (337 ± 78 MPa). Degradation studies were performed using a-amylase and/or lysozyme at concentrations similar to those found in human serum, at 37 C for up to 90 days. Scanning electron micrographs showed that enzymatic degradation caused a porous structure to be formed, indicating the potential of this methodology to obtain in situ forming scaffolds. In order to evaluate the biocompatibility of the scaffolds, extracts and direct contact tests were performed. Results with the MTT test showed that the extracts of the materials were clearly non-toxic to L929 fibroblast cells. Analysis of cell adhesion and morphology of seeded osteoblastic-like cells in direct contact tests showed that at day 7 the number of cells on CS80-20 and CS60-40 was noticeably higher than that on C100, which suggests that starch containing materials may promote cell adhesion and proliferation. This combination of properties seems to be a very promising approach to obtain scaffolds with gradual in vivo pore forming capability for bone tissue engineering applications.This work was supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283), the European STREP HIPPOCRATES (NMP3-CT-2003-505758) and the Portuguese Foundation for Science and Technology (FCT) through POCTI and/or FEDER programmes

Designing biomaterials based on biomineralization of bone

In nature, organisms control crystal nucleation and growth using organic interfaces as templates. Scientists, in the last decades, have tried to learn from nature how to design biomimetic biomaterials inspired by the hierarchical complex structure of bone and other natural mineralised tissues or to control the biomineralization process onto biomaterials substrates to promote the osteoconductive properties of implantable devices. The design of synthetic bone analogues, i.e., with a structure and properties similar to bone, would certainly constitute a major breakthrough in bone tissue engineering. Moreover, many strategies have been proposed in the literature to develop bioactive bone-like materials, for instance using bioactive glasses. Fundamental aspects of biomineralization may be also important in order to propose new methodologies to improve calcification onto the surface of biomaterials or to develop bioactive tridimensional templates that could be used in regenerative medicine. In particular, it has been shown that some chemical groups and proteins, as well as the tridimensional matrix in which calcification would occur, play a fundamental role on the nucleation and growth of hydroxyapatite. All these distinct aspects will be reviewed and discussed in this paper.I. B. Leonor thanks the Portuguese Foundation for Science and Technology (FCT) for providing her a post-doctoral scholarship (SFRH/BPD/26648/2006). This work was supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283) and by the Portuguese Foundation for Science and Technology, FCT, through the projects PTDC/CTM/68804/2006, PTDC/CTM/67560/2006 and PTDC/FIS/68209/2006