The limitation of mitral echocardiography in combined mitral lesions

In combined mitral stenosis and incompetence, the mitral echocardiogram is able to estimate the degree of mitral stenosis (i. e. mitral valve area) without being able to detect or quantify mitral incompetence. A diastolic closure rate of 20 mm/sec or less does not exclude significant mitral incompetence as claimed by others. Cardiac catheterization is still necessary in mitral stenosis, where concominant mitral incompetence is suspected clinically, to confirm its presence and quantify its degree.     

Co-chairman's remarks: genetic recombination in the molecular era

The present status of some general questions about DNA recombination is assessed. Topics include the mechanisms of synapsis and strand exchange, and the functions of recombination in nature.     

The roles of CD8 in cytotoxic T lymphocyte function

The CD8 glycoprotein of cytotoxic T cells is both an adhesion protein and a cosignalling receptor. These functions are regulated by signals from the T-cell antigen receptor complex (TCR-CD3), and CD8 acts to couple TCR occupancy to second messenger pathways. Here Anne O'Rourke and Matthew Mescher examine the roles of CD8 in activating the adhesion and signalling cascade initiated by antigen binding.