Method for the biomechanical analysis of aqueous veins and perilimbal sclera by three-dimensional photoacoustic imaging and strain field calculation.

A method motivated by the eye's aqueous veins is described for the imaging and strain calculation within soft biological tissues. A challenge to the investigation of the biomechanics of the aqueous vein-perilimbal sclera tissue complex is resolution of tissue deformations as a function of intraocular pressure and the subsequent calculation of strain (a normalized measure of deformation). The method involves perfusion of the eye with a contrast agent during conduction of non-invasive, optical resolution photoacoustic microscopy. This imaging technique permits three-dimensional displacement measurements of tracked points on the inner walls of the veins which are used in a finite element model to determine the corresponding strains. The methods are validated against two standard strain measurement methods. Representative porcine globe perfusion experiments are presented that demonstrate the power of the method to determine complex strain fields in the veins dependent on intraocular pressure as well as vein anatomy. In these cases, veins are observed to move radially outward during increases in intraocular pressure and to possess significant spatial strain variation, possibly influenced by their branching patterns. To the authors' knowledge, these are the only such quantitative, data driven, calculations of the aqueous vein strains available in the open literature.

Chiral synthesis of functionalized tetrahydropyridines: gamma-aminobutyric acid uptake inhibitor analogues.

[Chemical reaction: See text] A convenient preparation of functionalized chiral tetrahydropyridine-3-carboxylates from nitriles in 68-90% enantiomeric excess (ee) via allylboration, followed by a conjugate addition-elimination and ring-closing metathesis, has been developed. Thus, the treatment of the acetate derived from vinylalumination of formaldehyde by use of [alpha-(ethoxycarbonyl)vinyl]diisobutylaluminum with chiral beta-substituted and beta-unsubstituted homoallylic amines, prepared in >98% diastereomeric excess (de) and 68-90% ee via allylboration of the corresponding N-aluminoimines, furnished functionalized aminodienes, which underwent ring-closing metathesis to provide chiral C5-C6 disubstituted tetrahydropyridine-3-carboxylates. This methodology has been applied for the synthesis of a chiral C6-substituted tetrahydropyridine with known GABA-inhibiting properties at low concentrations.

Catalytic enantioselective synthesis of glutamic acid derivatives via tandem conjugate addition-elimination of activated allylic acetates under chiral PTC conditions.

A new, general, and practical procedure for the asymmetric synthesis of 4-alkylidenyl glutamic acid derivatives via a catalytic enantioselective tandem conjugate addition-elimination on allylic acetates under chiral phase-transfer conditions is reported. A variety of structural types of allylic acetates have been reacted with the benzophenone imine of glycine tert-butyl ester to give the products in good to excellent yields and enantioselectivities (63-92% yield, 80-97% ee, 8 cases).