Polysaccharide films built by simultaneous or alternate spray: a rapid way to engineer biomaterial surfaces.

We investigated polysaccharide films obtained by simultaneous and alternate spraying of a chitosan (CHI) solution as polycation and hyaluronic acid (HA), alginate (ALG), and chondroitin sulfate (CS) solutions as polyanions. For simultaneous spraying, the film thickness increases linearly with the cumulative spraying time and passes through a maximum for polyanion/CHI molar charge ratios lying between 0.6 and 1.2. The size of polyanion/CHI complexes formed in solution was compared with the simultaneously sprayed film growth rate as a function of the polyanion/CHI molar charge ratio. A good correlation was found. This suggests the importance of polyanion/polycation complexation in the simultaneous spraying process. Depending on the system, the film topography is either liquid-like or granular. Film biocompatibility was evaluated using human gingival fibroblasts. A small or no difference is observed in cell viability and adhesion between the two deposition processes. The CHI/HA system appears to be the best for cell adhesion inducing the clustering of CD44, a cell surface HA receptor, at the membrane of cells. Simultaneous or alternate spraying of CHI/HA appears thus to be a convenient and fast procedure for biomaterial surface modifications.journal articleresearch support, non-u.s. gov't2012 Jun 052012 05 23importe

Romantismo e objetividade: notas sobre um panorama do Rio de Janeiro

The article deals with the great Panorama of Rio de Janeiro exhibited in Paris, 1824, and its sources - a series of watercolours which have also generated succeeding engravings produced dur-ing the 1830s. Panoramas, in their early formal conventions are shown to interplay with Romanticism's and Naturphilosophie's theses and to put in motion the legacy of 11th-century paint-ing . As this geme of visual device develops, Rio's watercoulours display symptoms of a gradual dismissal of its initial ambilions, through lhe treatment of the natural site and the city. At last the invention of the daguerreotype and vai d'oiseau urban images, among other traits, signale the changes in sensibility related to the production and consumption of those circular canvasses. From 1840/50 on panoramas conceived by the will to fuse art and science and bya reflection on nature and liberty turn essentially into a mass entertainment.Romantismo e objetividade: notas sobre um panorama do Rio de Janeiro Margarelh da Silva Pereira Enfoca O grande Panorama do Rio de Janeiro, exibido em Paris em 1824, do qual se conhece a série de aquarelas que serviram de base tanto àquela ampliação quanto às sucessivas gravuras da cena que foram produzidas na década de 1830. Busca-se mostrar como os panoramas em sua formalização inicial dialogam com as teses do romantismo e da Naturphilosophie, mobilizan-do heranças da pintura seiscentista. No desenvolvimento desta forma de exibição as aquarelas do Rio apresentam sintomas do gradual afastamento das ambições iniciais através do tratamento dispensado ao sítio natural e à cidade. Por fim, a invenção do daguerreótipo, e as vistas urbanas em võo de pássaro, enlre outros, balizariam a mudança de sensibilidade na produção e na fruição dessas telas circulares. A partir de 1840/50 os panoramas engendrados pelo desejo de fusão entre arte e ciência e pela reflexão sobre a natureza e a liberdade, tornar-se-iam, sobretudo, um divertimento de massas

Comparative Study of Hematopoietic Differentiation between Human Embryonic Stem Cell Lines

Directed differentiation of human embryonic stem cells (hESCs) into any desired cell type has been hailed as a therapeutic promise to cure many human diseases. However, substantial roadblocks still exist for in vitro differentiation of hESCs into distinct cell types, including T lymphocytes. Here we examined the hematopoietic differentiation potential of six different hESC lines. We compare their ability to develop into CD34+ or CD34+CD45+ hematopoietic precursor populations under several differentiation conditions. Comparison of lymphoid potential of hESC derived- and fetal tissue derived-hematopoietic precursors was also made. We found diverse hematopoietic potential between hESC lines depending on the culture or passage conditions. In contrast to fetal-derived hematopoietic precursors, none of the CD34+ precursors differentiated from hESCs were able to develop further into T cells. These data underscore the difficulties in the current strategy of hESC forward differentiation and highlight distinct differences between CD34+ hematopoietic precursors generated in vitro versus in vivo

Os compostos fenólicos são mais influenciados pelos fatores clima e cultivar quando comparados aos perfis metabólicos de aminoácidos e RMN 1H.

o HPLC é um método analítico com excelente sensibilidade que permite analisar diferentes metabólitos a partir de extratos vegetais ou animais. Ele é usado com sucesso para a determinação de compostos fenólicos e aminoácidos de uvas e vinhos. Estes dois grupos de compostos são importantes para os padrões de qualidade no meio enológico. A concentração dos compostos relacionados pode variar fortemente em relação às condições do meio

Polysaccharide Films Built by Simultaneous or Alternate Spray: A Rapid Way to Engineer Biomaterial Surfaces

We investigated polysaccharide films obtained by simultaneous and alternate spraying of a chitosan (CHI) solution as polycation and hyaluronic acid (HA), alginate (ALG), and chondroitin sulfate (CS) solutions as polyanions. For simultaneous spraying, the film thickness increases linearly with the cumulative spraying time and passes through a maximum for polyanion/CHI molar charge ratios lying between 0.6 and 1.2. The size of polyanion/CHI complexes formed in solution was compared with the simultaneously sprayed film growth rate as a function of the polyanion/CHI molar charge ratio. A good correlation was found. This suggests the importance of polyanion/polycation complexation in the simultaneous spraying process. Depending on the system, the film topography is either liquid-like or granular. Film biocompatibility was evaluated using human gingival fibroblasts. A small or no difference is observed in cell viability and adhesion between the two deposition processes. The CHI/HA system appears to be the best for cell adhesion inducing the clustering of CD44, a cell surface HA receptor, at the membrane of cells. Simultaneous or alternate spraying of CHI/HA appears thus to be a convenient and fast procedure for biomaterial surface modifications

Biallelic, ubiquitous transcription from the distal germline Igκ locus promoter during B cell development

Allelic exclusion of Ig gene expression is necessary to limit the number of functional receptors to one per B cell. The mechanism underlying allelic exclusion is unknown. Because germline transcription of Ig and TCR loci is tightly correlated with rearrangement, we created two novel knock-in mice that report transcriptional activity of the Jκ germline promoters in the Igκ locus. Analysis of these mice revealed that germline transcription is biallelic and occurs in all pre-B cells. Moreover, we found that the two germline promoters in this region are not equivalent but that the distal promoter accounts for the vast majority of observed germline transcript in pre-B cells while the activity of the proximal promoter increases later in development. Allelic exclusion of the Igκ locus thus occurs at the level of rearrangement, but not germline transcription

Small-molecule-hosting nanocomposite films with multiple bacteria-triggered responses

We report pH/bacteria-responsive nanocomposite coatings with multiple mechanisms of antibacterial protection that include the permanent retention of antimicrobials, bacteria-triggered release of antibiotics and bacteria-induced film swelling. A novel small-molecule-hosting film was constructed using layer-by-layer deposition of montmorillonite (MMT) clay nanoplatelets and polyacrylic acid (PAA) components, both of which carry a negative charge at neutral pH. The films were highly swollen in water, and they exhibited major changes in swelling as a function of pH. Under physiologic conditions (pH 7.5, 0.2 M NaCl), hydrogel-like MMT/PAA films took up and sequestered similar to 45% of the dry film matrix mass of the antibiotic gentamicin, causing dramatic film deswelling. Gentamicin remained sequestrated within the films for months under physiologic conditions and therefore did not contribute to the development of antibiotic resistance. When challenged with bacteria (Staphylococcus aureus, Staphylococcus epidermidis or Escherichia coli), the coatings released PAA-bound gentamicin because of bacteria-induced acidification of the immediate environment, whereas gentamicin adsorbed to MMT nanoplatelets remained bound within the coating, affording sustained antibacterial protection. Moreover, an increase in film swelling after gentamicin release further hindered bacterial adhesion. These multiple bacteria-triggered responses, together with nontoxicity to tissue cells, make these coatings promising candidates for protecting biomaterial implants and devices against bacterial colonization