Cytocompatibility of poly(p-dioxanone)/ poly(hydroxybutic) (PPD/PHB) blends to cartilage tissue engineering

In order of seek strategies to improve the interaction between bioreabsorbable polymer materials and cellular growth, this work aimed at evaluating in vitro the influence of PPD/PHB blends on cell adhesion and fibrochondrocytes growth. Fibrochondrocytes cells were obtained by primary extraction from enzymatic digestion methods. The PPD/PHB blends were prepared by casting with 100/0, 60/40 and 50/50 compositions, and were characterized by scanning electron microscopy (SEM). After 6, 48, 120 and 168 hours in culture, ultrastructural observations showed changes in cell morphology, suggesting that the fibrochondrocytes can respond to substrate modifications, changing their phenotypic profile. The MTT analyses showed that the blends did not present cytotoxicity and allowed fibrochondrocytes adhesion and proliferation on the membranes in all compositions. The colorimetric Sirius Red test revealed the capability of extracellular matrix synthesis on the blends, from which one can conclude that the PPD/PHB blends are not cytotoxic and can be indicated for cell culture.Buscando estratégias que repercutam na melhoria da interação entre materiais poliméricos biorreabsorvíveis e o crescimento celular, o presente estudo in vitro teve como objetivo estudar a influência de blendas de PPD/PHB na adesão celular e crescimento de fibrocondrócitos obtidos a partir de cultura primária. As blendas de PPD/PHB foram preparadas pelo método de evaporação de solvente nas composições 100/0, 60/40 e 50/50 e caracterizadas por microscopia eletrônica de varredura (MEV). Observações ultra-estruturais mostraram alterações na morfologia celular, sugerindo que os fibrocondrócitos podem responder a alterações no substrato alterando seu perfil fenotípico. As análises com MTT demonstraram que as blendas não apresentaram citotoxicidade e permitiram a adesão e proliferação dos fibrocondrócitos sobre os substratos em todas as suas composições. O ensaio colorimétrico com Sirius Red evidenciou a capacidade de manutenção da síntese de matriz extracelular colágena sobre as amostras, concluindo-se que as blendas de PPD/PHB podem ser indicadas para o cultivo celular.383388Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Path integral for half-binding potentials as quantum mechanical analog for black hole partition functions

The semi-classical approximation to black hole partition functions is not well-defined, because the classical action is unbounded and the first variation of the uncorrected action does not vanish for all variations preserving the boundary conditions. Both problems can be solved by adding a Hamilton-Jacobi counterterm. I show that the same problem and solution arises in quantum mechanics for half-binding potentials.Comment: 6 pages, proceedings contribution to "Path integrals - New Trends and Perspectives", Dresden, September 200

The Effects of Cooperation; A Structural Model of Siblings’ Caregiving Interactions

Hervorming Sociale Regelgevin