Encapsulation of concentrated protein into erythrocyte porated by continuous-wave ultrasound.

A procedure of continuous-wave ultrasound (US)-induced hemolysis and reseal in solution containing water soluble protein was applied to a method for encapsulating concentrated protein solutions into resealed rat erythrocyte ghosts. To find a condition yielding a higher mean corpuscular concentration of encapsulated protein (MCC), we investigated the value of MCCs for various conditions. Additions of a small amount of plasma, Ca(2+) and Mg(2+) significantly increased MCC, whereas these additives did not alter the degree of hemolysis. It was suggested that plasma protect the molecular damages by the US, and that Ca(2+) and Mg(2+) physically stabilized the lipids of the erythrocyte membrane to fuse and reseal the pore induced by US. A maximal MCC of approximately 50 mg/mL, which is 2.5 times the reported maximum amount encapsulated by the osmotic dialysis method, was obtained without a blood-washing procedure.

Magnetic field exposure stiffens regenerating plant protoplast cell walls.

Single suspension-cultured plant cells (Catharanthus roseus) and their protoplasts were anchored to a glass plate and exposed to a magnetic field of 302 +/- 8 mT for several hours. Compression forces required to produce constant cell deformation were measured parallel to the magnetic field by means of a cantilever-type force sensor. Exposure of intact cells to the magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure to the magnetic field. Measured forces for regenerating protoplasts with and without exposure to the magnetic field increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye, and no changes were noted after exposure to the magnetic field. Analysis suggested that exposure to the magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.

Molecular damage to membrane proteins induced by ultrasound.

A dilute suspension of human erythrocytes was exposed in vitro to ultrasound (US) with a frequency of 1 MHz and an acoustic pressure of (3.0 +/- 0.4) x 10(5) Pa (intensity of 2.9 +/- 0.8 W/cm(2)). The degree of lysis of the cells in saline increased with increasing the exposure time. An addition of a small amount of plasma to the suspension did not change the degree of lysis. A gel electrophoresis of membrane proteins extracted from the exposed and lysed membrane samples showed that the exposure caused molecular damage in membrane proteins in the absence of plasma, and that the addition of the small amount of plasma protected the proteins against the molecular damage.