Vitronectin as a micromanager of cell response in material-driven fibronectin nanonetworks

Surface functionalization strategies of synthetic materials for regenerative medicine applications comprise the development of microenvironments that recapitulate the physical and biochemical cues of physiological extracellular matrices. In this context, material-driven fibronectin (FN) nanonetworks obtained from the adsorption of the protein on poly(ethyl acrylate) provide a robust system to control cell behavior, particularly to enhance differentiation. This study aims at augmenting the complexity of these fibrillar matrices by introducing vitronectin, a lower-molecular-weight multifunctional glycoprotein and main adhesive component of serum. A cooperative effect during co-adsorption of the proteins is observed, as the addition of vitronectin leads to increased fibronectin adsorption, improved fibril formation, and enhanced vitronectin exposure. The mobility of the protein at the material interface increases, and this, in turn, facilitates the reorganization of the adsorbed FN by cells. Furthermore, the interplay between interface mobility and engagement of vitronectin receptors controls the level of cell fusion and the degree of cell differentiation. Ultimately, this work reveals that substrate-induced protein interfaces resulting from the cooperative adsorption of fibronectin and vitronectin fine-tune cell behavior, as vitronectin micromanages the local properties of the microenvironment and consequently short-term cell response to the protein interface and higher order cellular functions such as differentiation

Social consequences of the privatization in Bulgaria and socio-economic impact of the neo-liberal economic theory on the transition to free market and democracy in the period from 1989 to 2015

Objectifs : Le mémoire examine la privatisation en Bulgarie à partir d'une certaine distance historique de 25 ans, pour démontrer les conséquences sociales présentement visibles, entre autres les inégalités sociales par rapport au développement économique; l’impact démographique aussi que les nouvelles structures et valeurs sociales. Méthode: Nous utilisons une approche à deux volets. Pour le développement socio-économique, nous étudions six variables constantes pour la période, telles que le nombre de personnes en dessous du seuil de pauvreté, le PIB, l'indice Gini, les dynamiques démographiques, le taux de chômage et l'indice de développement humain; Pour les changements sociaux, les nouvelles structures et les valeurs, nous utiliserons une approche qualitative, basée sur des entrevues, des questionnaires, des études de terrain, etc. Résultats: Nous constatons que les résultats obtenus par les deux méthodes, ceci comprenant leurs limitations, correspondent plutôt à notre hypothèse : la privatisation en Bulgarie était économiquement nécessaire, mais socialement destructive et a entraîné des conséquences sociales dévastatrices à long terme, principalement en raison des politiques et des pratiques de privatisation défectueuses. La privatisation a émergé de la théorie néo-libérale économique prédominant à l'époque. Les pratiques spécifiques utilisées dans la privatisation Bulgare ont favorisé principalement à court terme certains petits groupes sociaux, mais pas la société dans son ensemble. Conclusion: Nous constatons que la façon dont la privatisation bulgare a été menée a été socialement et économiquement nuisible avec des conséquences continues. À long terme, l'économie s'est rétablie, mais les divergences sociales ont toujours une tendance à croître.Objectives : We look at the privatization in Bulgaria as defined above from a certain historical distance of 25 years, trying follow the visible now social consequences of the privatization, such as social inequality vs economic development; demographic impact and new social structures and values. Method: We use a two-prong approach. For the socio-economic development we study six constant variables for the defined period such as number of people below poverty line, GDP, Gini Index, demographic dynamcs, employment rate, and Human development index; for the social changes, new structures and values we use a qualitative approach, based on based on interviews, questionnaires, field studies, etc. Results: We find that results by both methods, with all the limittaions they have, rather align with our hypothesis that privatization in Bulgaria was economically necessary, but socially destructive and led to devastating social consequences, mainly as a result of flawed privatization policies and practices. It did emerge from the predominant at that time neo-liberal economic view and the specific practices used in the Bulgarian privatization favoured mainly in short term for some small social groups but for the society as a whole. Conclusion: We find that the way Bulgarian privatization was conducted was socially and economically damaging with long lasting consequences. In the long run the economy has recoverd, however the social divergences tend to grow

Vitronectin activity on polymer substrates with controlled –OH density

Vitronectin (VN) adsorption on a family of model substrates consisting of copolymers of ethyl acrylate and hydroxyl ethylacrylate in different ratios (to obtain a controlled surface density of –OH groups) was investigated by Atomic Force Microscopy (AFM). It is shown that the fraction of the substrate covered by the protein depends strongly on the amount of hydroxyl groups in the sample and it monotonically decreases as the –OH density increases. Isolated globular-like VN molecules are observed on the surfaces with the higher OH density. As the fraction of hydroxyl groups decreases, aggregates of 3–5 VN molecules are observed on the sample. Overall cell morphology, focal adhesion formation and actin cytoskeleton development are investigated to assess the biological activity of the adsorbed VN on the different surfaces. Dermal fibroblast cells show excellent material interaction on the more hydrophobic samples (OH contents lower than 0.5), which reveals enhanced VN activity on this family of substrates as compared with other extracellular matrix proteins (e.g., fibronectin and fibrinogen)

Plastocyanin microheterogeneity in Scenedesmus acutus MT8

310-316Two total plastocyanin (PC) fractions — loosely bound (lPC) and strongly bound (sPC) were extracted (84% and 16%, respectively) from the homogenate of Scenedesmus acutus MT8. Two-fold isolation-purification procedure including DE-52 chromatography separated lPC into a smaller oxidized [lPC (II)] and a larger reduced [lPC(I)] fractions, in contrast to sPC, where sPC(II) greatly dominated over sPC(I). Analytical isoelectric focusing (IEF) separated lPC(II) into two main fractions only in the presence of 8 M urea, implying microheterogeneity. Preparative IEF in immobiline pH-gradient of 3.2-4.1 separated lPC(II) into two blue fractions – a more alkaline lPC'(II) and a more acidic lPC''(II), which were probably stereoisomers. Their UV-Vis spectra exhibited rarely observed tryptophane (291.5 nm) and some differences at 270 and 287 nm. The exact molecular masses of apo-/holo-lPC (10131 Da/10194 Da) were determined by mass spectrometry. The number of -SH groups was determined from the mass difference between alkylated with 4-vinylpyridine (4-VP) and nonalkylated protein. Additionally, a simple procedure for simultaneous separation of both primary structure and stereoisomers of PC was developed