Analytic-domain lens design with proximate ray tracing.

We have developed an alternative approach to optical design which operates in the analytical domain so that an optical designer works directly with rays as analytical functions of system parameters rather than as discretely sampled polylines. This is made possible by a generalization of the proximate ray tracing technique which obtains the analytical dependence of the rays at the image surface (and ray path lengths at the exit pupil) on each system parameter. The resulting method provides an alternative direction from which to approach system optimization and supplies information which is not typically available to the system designer. In addition, we have further expanded the procedure to allow asymmetric systems and arbitrary order of approximation, and have illustrated the performance of the method through three lens design examples.

G protein signaling and vein graft intimal hyperplasia: reduction of intimal hyperplasia in vein grafts by a Gbetagamma inhibitor suggests a major role of G protein signaling in lesion development.

Vein grafting results in the development of intimal hyperplasia with accompanying changes in guanine nucleotide-binding (G) protein expression and function. Several serum mitogens that act through G protein-coupled receptors, such as lysophosphatidic acid, stimulate proliferative pathways that are dependent on the G protein betagamma subunit (Gbetagamma)-mediated activation of p21ras. This study examines the role of Gbetagamma signaling in intimal hyperplasia by targeting a gene encoding a specific Gbetagamma inhibitor in an experimental rabbit vein graft model. This inhibitor, the carboxyl terminus of the beta-adrenergic receptor kinase (betaARK(CT)), contains a Gbetagamma-binding domain. Vein graft intimal hyperplasia was significantly reduced by 37% (P<0.01), and physiological studies demonstrated that the normal alterations in G protein coupling phenotypically seen in this model were blocked by betaARK(CT) treatment. Thus, it appears that Gbetagamma-mediated pathways play a major role in intimal hyperplasia and that targeting inhibitors of Gbetagamma signaling offers novel intraoperative therapeutic modalities to inhibit the development of vein graft intimal hyperplasia and subsequent vein graft failure.