Electrospun silk-elastin-like fiber mats for tissue engineering applications

Protein-based polymers are present in a wide variety of organisms fulfilling structural and mechanical roles. Advances in protein engineering and recombinant DNA technology allow the design and production of recombinant protein-based polymers (rPBPs) with an absolute control of its composition. Although the application of recombinant proteins as biomaterials is still an emerging technology, the possibilities are limitless and far superior to natural or synthetic materials, as the complexity of the structural design can be fully customized. In this work, we report the electrospinning of two new genetically engineered silk-elastin-like proteins (SELPs) consisting of alternate silk- and elastin-like blocks. Electrospinning was performed with formic acid and aqueous solutions at different concentrations without addition of further agents. The size and morphology of the electrospun structures was characterized by scanning electron microscopy showing to be dependent of concentration and solvent used. Treatment with air saturated with methanol was employed to stabilize the structure and promote water insolubility through a time-dependent conversion of random coils into β-sheets (FTIR). The resultant methanol-treated electrospun mats were characterized for swelling degree (570-720%), water vapour transmission rate (1083 g/m2/day) and mechanical properties (modulus of elasticity of ~126 MPa). Furthermore, the methanol-treated SELP fiber mats showed no cytotoxicity and were able to support adhesion and proliferation of normal human skin fibroblasts. Adhesion was characterized by a filopodia-mediated mechanism. These results demonstrate that SELP fiber mats can provide promising solutions for the development of novel biomaterials suitable for tissue engineering applications.

Effect of poling state and morphology of piezoelectric poly(vinylidene fluoride) membranes for skeletal muscle tissue engineering

This work reports on the influence of polarization and morphology of electroactive poly(vinylidene fluoride), PVDF, on the biological response of myoblast cells. Non-poled, ‘‘poled +’’ and “poled-“ -PVDF were prepared in the form of films. Further, random and aligned electrospun -PVDF fiber mats were also prepared. It is demonstrated that negatively charged surfaces improve cell adhesion and proliferation and that the directional growth of the myoblast cells can be achieved by the cell culture on oriented fibers. Therefore, the potential application of electroative materials for muscle regeneration is demonstrated.

Variations of the soft tissue thicknesses external to the ribs in Pectus Excavatum patients

Background: Surgical repair of pectus excavatum (PE) has become more popular due to improvements in the minimally invasive Nuss procedure. The pre-surgical assessment of PE patients requires Computerized Tomography (CT), as the malformation characteristics vary from patient to patient. Objective: This work aims to characterize soft tissue thickness (STT) external to the ribs among PE patients. It also presents a comparative analysis between the anterior chest wall surface before and after surgical correction. Methods: Through surrounding tissue segmentation in CT data, STT values were calculated at different lines along the thoracic wall, with a reference point in the intersection of coronal and median planes. The comparative analysis between the two 3D anterior chest surfaces sets a surgical correction influence area (SCIA) and a volume of interest (VOI) based on image processing algorithms, 3D surface algorithms, and registration methods. Results: There are always variations between left and right side STTs (2.54±2.05 mm and 2.95±2.97 mm for female and male patients, respectively). STTs are dependent on age, sex, and body mass index of each patient. On female patients, breast tissue induces additional errors in bar manual

Factores determinantes do nível de divulgação sobre instrumentos derivados de acordo com as recomendações do Basel Committee on Banking Supervision e da Organisation of Securities Commissions - evidência empírica no sector bancário português

Este estudo analisa o nível de divulgação sobre instrumentos derivados e seus factores determinantes nas entidades bancárias portuguesas. Para o efeito, foi utilizado um índice de divulgação, baseado nas recomendações emitidas pelo Basel Committee on Banking Supervision e pela Organisation of Securities Commissions, e analisados os Relatórios & Contas anuais, individuais, relativos a 2009. Conclui-se que o número de empresas que apresenta informação sobre a utilização de instrumentos derivados é bastante elevado, mas o valor médio de divulgação apresentado é bastante reduzido. Identificam-se, como factores determinantes do nível de divulgação, o tamanho da empresa, a qualidade do auditor externo e o facto de a empresa ter procedido a um aumento de capital durante o exercício económico em análise.

Grau de cumprimento com as recomendações do Basel Committee on Banking Supervision e da Organisation of Securities Commissions, sobre divulgação de informação relacionada com instrumentos derivados - evidência empírica no sector bancário português

This study analyzes the level of disclosure on derivatives, in accordance with the recommendations issued by the Basel Committee on Banking Supervision and the Organization of Securities Commission, by Portuguese banks. We have analyzed individual annual reports related to 2009, using a disclosure index based on those recommendations. We concluded that the number of companies that provides information about derivative instruments is quite high, but the average value of disclosure is very low. The information disclosed more frequently is that related to general aspects, followed by information related to accounting and valuation methods.

Estudo do grau de cumprimento com as recomendações do Basel Committee on Banking Supervision e da Organisation of Securities Commissions, sobre divulgação de informação relacionada com instrumentos derivados, pelas entidades portuguesas pertencentes ao sector bancário

Este estudo analisa o nível de divulgação sobre instrumentos derivados, de acordo com as recomendações emitidas pelo Basel Committee on Banking Supervision e pela Organisation of Securities Commissions, pelas entidades bancárias portuguesas. Para o efeito, foi utilizado um índice de divulgação e analisados os Relatórios & Contas anuais, individuais, relativos a 2009. Conclui-se que o número de empresas que apresenta informação sobre a utilização de instrumentos derivados é bastante elevado, mas o valor médio de divulgação apresentado é bastante reduzido. A informação mais divulgada é a relativa a informações gerais, seguida da informação relacionada com contabilidade e métodos de avaliação.

Variations of the soft tissue thicknesses external to the ribs in pectus excavatum patients

Background: Surgical repair of pectus excavatum (PE) has become more popular due to improvements in the minimally invasive Nuss procedure. The pre-surgical assessment of PE patients requires Computerized Tomography (CT), as the malformation characteristics vary from patient to patient. Objective: This work aims to characterize soft tissue thickness (STT) external to the ribs among PE patients. It also presents a comparative analysis between the anterior chest wall surface before and after surgical correction. Methods: Through surrounding tissue segmentation in CT data, STT values were calculated at different lines along the thoracic wall, with a reference point in the intersection of coronal and median planes. The comparative analysis between the two 3D anterior chest surfaces sets a surgical correction influence area (SCIA) and a volume of interest (VOI) based on image processing algorithms, 3D surface algorithms, and registration methods. Results: There are always variations between left and right side STTs (2.54±2.05 mm and 2.95±2.97 mm for female and male patients, respectively). STTs are dependent on age, sex, and body mass index of each patient. On female patients, breast tissue induces additional errors in bar manual