RESUMO
Bacterial cellulose (BC) is an emerging alternative to plant cellulose in different applications. Several works demonstrated the potential of never-dried BC; however, envisioning real industrial applications, a dry product retaining its functional properties upon rehydration is preferable. A dry and completely redispersible formulation of BC with carboxymethyl cellulose (CMC) was prepared by Spray-drying. The obtained material showed a Zeta Potential of (-67.0⯱â¯3.9) mV, a Dv(50) of (601⯱â¯19.7) µm and was able to decrease the oil/water interface energy. The dry BC:CMC formulation was employed as a stabilizer in oil-in-water emulsions, in parallel with commercial plant celluloses and Xanthan gum. The emulsions were monitored over time by optical microscopy and characterized by rheological measurements. BC:CMC effectively stabilized emulsions against coalescence and creaming, at a concentration of 0.50 % - contrarily to other commercial dry celluloses - due to the Pickering effect and to the structuring of the continuous phase, as seen with Cryo-SEM.
Assuntos
Bactérias/metabolismo , Carboximetilcelulose Sódica/química , Dessecação , Emulsões/química , Polissacarídeos Bacterianos/química , Tensão SuperficialRESUMO
In this work, polypyrrole (PPy) was in situ polymerized onto the surface of bacterial nanocellulose (BNC) produced by Gluconacetobacter xylinus, by chemical oxidation in aqueous medium using ammonium persulfate. Composites (BNC/PPy) were produced with varying concentrations of pyrrole (Py). The produced BNC/PPy membranes were used as a template for the seeding of PC12 rat neuronal cells. Cell suspensions were directly seeded onto the surfaces of the BNC/PPy membranes. The Py concentration affected the behavior of neuronal cells that adhered and grew significantly more on BNC/PPy comparatively to BNC. Scanning electron microscopy (SEM) micrographs revealed that PC12 cells adhered on the surface of the BNC and BNC/PPy membranes. Conductive PPy coatings on nanofibers acting as an active interface for tissue engineering may be used to regulate cell activity through electrical stimulations.
Assuntos
Celulose/química , Materiais Revestidos Biocompatíveis/farmacologia , Neurônios/efeitos dos fármacos , Polímeros/química , Polímeros/farmacologia , Pirróis/química , Pirróis/farmacologia , Alicerces Teciduais/química , Animais , Materiais Revestidos Biocompatíveis/química , Condutividade Elétrica , Teste de Materiais , Nanopartículas/química , Neurônios/fisiologia , Células PC12 , Polissacarídeos Bacterianos/química , Ratos , Propriedades de Superfície , Técnicas de Cultura de Tecidos/instrumentação , Engenharia TecidualRESUMO
Autism spectrum disorders (ASD) is a group of behaviorally defined neurodevelopmental disabilities characterized by multiple genetic etiologies and a complex presentation. Several studies suggest the involvement of the serotonin system in the development of ASD, but only few have investigated serotonin receptors. We have performed a case-control and a family-based study with 9 polymorphisms mapped to two serotonin receptor genes (HTR1B and HTR2C) in 252 Brazilian male ASD patients of European ancestry. These analyses showed evidence of undertransmission of the HTR1B haplotypes containing alleles -161G and -261A at HTR1B gene to ASD (P=0.003), but no involvement of HTR2C to the predisposition to this disease. Considering the relatively low level of statistical significance and the power of our sample, further studies are required to confirm the association of these serotonin-related genes and ASD.
Assuntos
Transtorno Autístico/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único , Receptor 5-HT1B de Serotonina/genética , Receptor 5-HT2C de Serotonina/genética , Alelos , Brasil , Estudos de Casos e Controles , Família , Genótipo , Haplótipos , Humanos , Masculino , Análise de Sequência de DNARESUMO
A cellulase from Trichoderma reesei was immobilized on Eudragit L-100, a reversibly soluble polymer depending on the pH of the medium. The solubility of the modified cellulase was studied at different pH values. By changing the pH, the adsorption equilibrium of the derivatized proteins is switched towards the liquid phase, thus making recycling possible. This method allows for improved stability, without major loss of specific activity. The adsorption of cellulase on Eudragit lowers the enthalpy of denaturation, but affects only slightly the denaturation temperature. The use of carbodiimide was ineffective on linking the enzymes covalently to the polymer, since the immobilization process was found to be only mediated by non-covalent forces.
Assuntos
Celulase/metabolismo , Ácidos Polimetacrílicos/química , Ácidos Polimetacrílicos/metabolismo , Adsorção , Estabilidade Enzimática , Enzimas Imobilizadas , Concentração de Íons de Hidrogênio , Sensibilidade e Especificidade , Solubilidade , Trichoderma/enzimologiaRESUMO
Acute or chronic zinc administration may cause hyperglycemia in experimental animals. These findings are attributed to permissive actions of glucocorticoids and glucagon upon hepatic gluconeogenesis and glycogenolysis. The effect of Zn(+)+ on plasma glucose, C-peptide, glucagon, and cortisol was investigated in healthy and insulin-dependent diabetes mellitus (IDDM) patients. Ten normal individuals (5 of each sex, aged 24.10 +/- 1.96) and 10 IDDM (5 of each sex, aged 25.20 +/- 8.10) were tested at 7:00 AM after 12-h fast. Twenty-five mg of Zn(+)+ were administered intravenously during 1 min, and blood samples were collected from the contralateral arm at 0, 3, 30, 60, 90 and 120 min after Zn(+)+ injection. The plasma levels of glucose, C-peptide, and glucagon remained constant throughout the experimental period in both groups studied. Plasma cortisol levels decreased significantly, which is consistent with our previous findings. These results suggest that, in contrast to experimental animals, acute Zn(+)+ administration, despite decreasing cortisol levels, does not change carbohydrate metabolism in human beings.
