Biomechanical effects of the nail entry zone and anterior cortical bone loss on the proximal tibia.

Objectives: The aims of this study were as follows: to determine if the presence of the nail entry zone alters the biomechanics of the proximal tibia after intramedullary (IM) nailing using a computational model; to determine if nail removal restores normal biomechanics to the proximal tibia; and to determine if these effects are magnified with anterior cortical bone loss.

Methods: Three-dimensional finite element (FE) tibial models were developed and used for this study: an intact tibia, a nailed tibia, and a tibia with the nail removed. One matched pair of fresh-frozen cadaver tibias was obtained to construct and validate the FE model.

Chronic exposure to methylphenidate impairs appendicular bone quality in young rats.

Methylphenidate (MP) is a psychostimulant widely prescribed to treat Attention Deficit Hyperactivity Disorder (ADHD). Although generally well tolerated, growth deficits have been reported in children and adolescents undergoing MP treatment. This study was designed to elucidate the skeletal effects of chronic MP administration in adolescent rats.

Is humeral segmental defect replacement device a stronger construct than locked IM nailing?

Intramedullary (IM) nailing is currently the most common method for treating patients with impending pathologic humeral fractures; however, this treatment is associated with known complications primarily owing to violation of the rotator cuff during insertion. A better option is needed. To determine if a humeral segmental replacement prosthesis would provide a stronger construct compared with an IM nail in this setting, we compared the mechanical properties of these two devices in a cadaver model simulating an impending pathologic fracture.

Analysis of the methylated 'cap' structures of vaccinia mRNA by two-dimensional thin-layer chromatography.

Two different twodimensional cellulose thinlayer separations for blocked, methylated mRNA 5'-termini are described. They allow rapid analysis even of complex mixtures of mRNA "cap" structures on the basis of their methyl group content and base composition. These simple procedures are especially useful for the analysis of [3H-methyl]-labeled mRNA in combination with tritium fluorography.