Permeability to ions of bovine retinal disk membrane vesicles in the bleached state

The permeability of the bleached disk membrane of retinal rod outer segments to univalent and divalent ions is studied by light scattering. The membranes are isolated from frozen dark-adapted bovine retinae, swollen into spherical vesicles in a hypotonic medium and bleached in dilute suspension and their size is determined by elastic and quasi-elastic light scatterings. Various electrolytes are then added to the suspending medium in order to examine their osmotic activity relative to the vesicles deformation characteristics. By following the deformation behavior of the membrane vesicles by elastic light scattering in terms of the oblate ellipsoidal shell model, the osmotic activity of a given electrolyte is qualitatively deduced and thereby the permeability of the membrane to the electrolyte is ranked in reference to a chosen standard, i.e., sucrose. By this method, we show that the permeabilities to Na+, K+, Mg2+ and Ca2+ are all alike, and those to halides (F-, Cl-, Br-, I-), nitrate and phosphates (HPO4(2-)/H2PO4-) are similar. Acetate, however, is about 3-times more permeative, while sulfate is less permeative than the other anions by about the same factor. The viability of our method is checked with use of an ionophore, lasolocid (X-537A), by establishing partial recovery from the osmotic deformation through the suppression of the cation osmotic effect. Ion-induced aggregation and pH-dependent size and shape changes are both found to be insignificant.

Dynamic kerr effect measurements on photoreceptor disk membrane vesicles

Dynamic Kerr effect measurements were performed with dilute aqueous suspensions of monodisperse spherical vesicles (approximately 1 micron diameter), isolated from the rod outer segment of bovine retina. A large birefringence, amounting to the specific Kerr constant of 10(-3) esu, can be observed. When a sufficiently long duration pulse (1 s) is applied, the decay of birefringence can be represented by a single exponential profile, yielding a relaxation time of 100 +/- 20 ms in 1 mM imidazole buffer. This is consistent with the rotatory relaxation time of these spherical membrane vesicles. When a short duration is applied, the birefringence increases more steeply and the decay profile contains several components. The slowest (terminal) relaxation time is 86 +/- 15 ms is due to the same process as the one observed in the slow pulse case.

Photoinduced size change of membrane vesicles from bovine retinal rod outer segment

Quasielastic light-scattering measurements were made on isolated, osmotically swollen, bovine rod outer segment (ROS) disk membranes in aqueous Ficoll. The translational diffusion coefficients determined were (1.66 +/- 0.21) X 10(-9) and (2.31 +/- 0.14) X 10(-9) cm2/s at 25 degrees C for the unbleached and bleached membranes in 5% Ficoll, respectively, yielding the Stokes radii of 0.53 +/- 0.07 micronm for the former and 0.38 +/- 0.02 micronm for the latter. This photoinduced size decrease, which corresponds to a 60% decrease in the intravesicular volume, is far more pronounced than thos reported by others for ROS fragments.

Intact photoreceptor membrane from bovine rod outer segment: size and shape in bleached state

Photoreceptor disk membranes isolated from bovine rod outer segments are suspended in dilute aqueous sucrose (4.36 X 10(-3%)) and bleached, and their size and shape are determined with quasielastic and elastic light scattering. They are found to be extremely homogeneous spherical vesicles with a radius of 0.49 +/- 0.07 mum which appear to have derived from the native disk shape by osmotic swelling.

Emergency surgery for calculous diseases of the upper urinary tract

Nineteen patients with calculous disease of the upper urinary tract presenting as anuria or acute pyonephrosis are reported. The necessity for emergency surgical treatment is stressed. The methods of surgical treatment and the results are discussed.