[Surgical treatment of recurrent urethral strictures in males after unsuccessful operations].

Background: Subvesical obstructions of any origin represent a frequent and serious disorder occurring predominantly in males. Often it brings incontinence and/or erectility dysfunction, infection of urinary tract. Relapses of the acute pyelonephritis can turn into chronic tubulointersticial one and terminate in the renal insufficiency.

Development of fixable stent for long-term derivation of lower urinary tract.

The object of the envisaged project is the development of easily fixable non-irritant stent of the lower urinary tract. The project has the aim to remove the obstruction and make passage-way through urethra which, after repeated operations, remains narrowed and requires repeated dilatations or, in the patients who have a chronic epicystostomy due to the non-passable urethra. The prosthesis must be self fixable, non-irritant, easily introduceable and removable by endoscopy, enabling normal urination with urinary continence and, last but not least, at a reasonable price.

Silicone rubber-hydrogel composites as polymeric biomaterials. IX. Composites containing powdery polyacrylamide hydrogel.

A composite material has been prepared consisting of a silicone rubber matrix and particulate lightly cross-linked polyacrylamide hydrogel. The material, resembling common silicone rubber, is hydrophilic and swells in water like hydrogels. The polyacrylamide has a high specific surface area, a relatively low content of water-soluble low-molecular-weight compounds and, owing to its non-ionogenic character, a pH-independent swelling degree.

Silicone rubber-hydrogel composites as polymeric biomaterials. VI. Transport properties in the water-swollen state.

Permeation of inorganic salts in water-swollen silicone rubber-hydrogel composites consisting of a silicone rubber matrix and lightly cross-linked particles of poly(2-hydroxyethyl methacrylate), poly(2-hydroxyethyl methacrylate-co-methacrylic acid), poly(methacrylic acid), polyacrylamide or poly(acrylamide-co-methacrylic acid) hydrogels was investigated. The results, together with earlier data on permeation of non-ionic low-molecular-weight substances through the composite materials, were evaluated in terms of the free-volume diffusion theory. It was found that the materials with water content exceeding a certain limit are highly permeable to the salts, and that, as regards permeation properties, they behave as homogeneous water-swollen hydrogels.

Silicone rubber-hydrogel composites as polymeric biomaterials. IV. Silicone matrix-hydrogel filler interaction and mechanical properties.

Composite materials consisting of a silicone rubber matrix and particulate synthetic hydrogels were prepared and their mechanical properties were studied. The influence of the size, shape, aggregation of hydrogel particles, chemical reactions of polymer phases on tensile properties and tear strength of the composite materials were investigated. The relations between the properties, structure and chemical composition of polymer phases of the composite materials and their mechanical properties are discussed.