Women & smoking: becoming part of the solution.

El hecho de que tantas enfermedades, ya sean graves o leves, estén relacionadas con el tabaquismo es una de las conclusiones más asombrosas de la investigación médica de este siglo; si bien es posible que no sea tan sorprendente como el hecho de que tantas personas lo hayan ignorado. ­Sir Richard Doll, 1912­2005 Las empresas transnacionales del tabaco minimizan los peligros de fumar en poderosas campañas de publicidad desplegadas alrededor del mundo, al mismo tiempo que los organismos internacionales e instituciones sanitarias se esfuerzan por contrarrestar estos mensajes mediáticos con presupuestos ínfimos: una asimetría asombrosa que pone en peligro la salud de millones de personas.

The molecular interactions that influence the plasticizer dependent dissolution of acrylic polymer films.

Poly(methacrylic acid-methyl methacrylate, 1:2) (Eudragit S) is a commonly used pH-responsive polymer that can facilitate delivery to the ileo-colonic region of the gastrointestinal tract. Different plasticizers have been used to reduce the brittleness of Eudragit S films for the coating of solid dosage forms. To better correlate the dissolution rates of Eudragit S films, we have examined their dielectric response to understand the specific polymer-plasticizer interactions. Solvent cast Eudragit S films were prepared with one of four citrate plasticizers ranging from low to moderate aqueous solubility. Film dissolution was determined using a two-compartment permeation cell. Dielectric properties were measured by thermally stimulated depolarisation currents (TSDC). Secondary relaxations were deconvoluted and identified. The glass transition temperature (T(g)) was measured using TSDC, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Dissolution of the films was influenced by the solubility and structure of the plasticizers. While no correlation was found among the T(g)'s obtained by TSDC, DSC, and DMA with dissolution time, the low temperature TSDC spectra showed a relationship of the total secondary relaxation area and relaxation of the carboxylic acid functional group with dissolution time. Dielectric secondary relaxations may be a good probe to predict plasticizer influence on dissolution of Eudragit S polymer films.

In vitro deposition of hydroxyapatite on cortical bone collagen stimulated by deformation-induced piezoelectricity.

In the present work, we have studied the effect of the piezoelectricity of elastically deformed cortical bone collagen on surface using a biomimetic approach. The mineralization process induced as a consequence of the piezoelectricity effect was evaluated using scanning electron microscopy (SEM), thermally stimulated depolarization current (TSDC), and differential scanning calorimetry (DSC). SEM micrographs showed that mineralization occurred predominantly over the compressed side of bone collagen, due to the effect of piezoelectricity, when the sample was immersed in the simulated body fluid (SBF) in a cell-free system. The TSDC method was used to examine the complex collagen dielectric response. The dielectric spectra of deformed and undeformed collagen samples with different hydration levels were compared and correlated with the mineralization process followed by SEM. The dielectric measurements showed that the mineralization induced significant changes in the dielectric spectra of the deformed sample. DSC and TSDC results demonstrated a reduction of the collagen glass transition as the mineralization process advanced. The combined use of SEM, TSDC, and DSC showed that, even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen can produce the precipitation of hydroxyapatite by electrochemical means, without a catalytic converter as occurs in classical biomimetic deposition.