Determination of microgram quantities of tin(IV) by a combined ion-exchange/X-ray fluorescence technique

A method is described for the analysis of microgram quantities of tin in dilute hydrofluoric acid. The tin is extracted onto anion-exchange resin loaded paper discs by a very simple technique and the papers are examined by X-ray fluorescence spectrography. The solutions are obtained by the dissolution of tin-containing glasses, and the normal glass-forming elements do not interfere. The method is intended for the determination of 1-20 mug of tin but may be used for up to at least 250 mug; 5 mug can be determined with a precision of +/- 10%.     

Differential expression of the skeletal muscle proteome in mdx mice at different ages

The mdx mouse is the most commonly used animal model for Duchenne muscular dystrophy (DMD), a disease caused by the absence of dystrophin. Although much has been done to elucidate the structure and function of dystrophin and the dystrophin-associated glycoprotein complex (DGC), little is known about the cascade of molecular events triggered by the absence of dystrophin that lead to muscle degeneration. To study the molecular basis of DMD, we decided to systematically study the skeletal muscle proteome in mdx mice at different ages. By using two-dimensional (2-D) gel electrophoresis, we defined changes in the protein expression pattern between mdx and control muscles. Approximately 46 differentially expressed proteins from the cytosolic fraction of mdx hindlimb muscles at three months of age were detected by 2-D gel analysis, of which 24 were identified by matrix assisted laser desorption/ionization- mass spectrometry. Most of the proteins fell into five groups of functionally related proteins. These functional categories are (i) metabolism and energy production, (ii) serine protease inhibitor family, (iii) growth and differentiation, (iv) calcium homeostasis, and (v) cytoskeletal reorganization and biogenesis. The potential roles of the differentially expressed proteins are discussed in the context of the mdx phenotype. Finally, we analyzed alterations of protein expression in mdx mice at one and six months of age to determine how protein expression changes with disease progression.