Structural alterations of p(HEMA)--collagen implants.

Samples of linear (additionally crosslinked) p(HEMA) with different amounts of fibrillar collagen were implanted into the popliteal region of rats. After 3 month, the implanted materials were harvested and examined by SEM. The implants underwent marked structural or morphological changes.

Silicone rubber-hydrogel composites as polymeric biomaterials. I. Biological properties of the silicone rubber-p(HEMA) composite.

A composite material was prepared consisting of silicone rubber matrix and particulate lightly cross-linked poly(2-hydroxyethyl methacrylate) (p(HEMA] hydrogel. The material resembling common silicone rubber is hydrophilic and swells in water like hydrogels. The effects of the implanted composite on tissues of the living organism were tested in rats by methods assessing local acute and chronic inflammatory reactions and calcification by means of radioactive indicators and by histological examination.

Irritation effects of residual products derived from p(HEMA) gels. II. Compounds extracted from hydrogels.

Samples of poly(2-hydroxyethyl methacrylate) p(HEMA) hydrogels were prepared using three different polymerization initiators. The gels were washed in water under standard conditions. The extracts were then examined for intradermal irritation in rats using a radioactive indicator (113mIn).

Irritation effects of residual products derived from poly(2-hydroxyethyl methacrylate) gels. I. Testing of some model compounds.

2-Hydroxyethyl methacrylate (HEMA) monomer and sodium benzoate, diluted with saline in the range 0-20%, were tested for intradermal irritation in rats. Radioactive indicator (113mIn) was used to quantify this biological response. At low concentrations (up to 1%) only a little irritation was recorded, while at higher levels (5% or more) a significant adverse reaction developed.

Calcification of poly(2-hydroxyethyl methacrylate)-collagen composites implanted in rats.

Samples of the polyHEMA-collagen composites with varying collagen content have been implanted into the popliteal region of rats. Three, six and twelve months after the implantation, calcification of the implanted material was determined using a radioactive indicator. At the same time, the implants and surrounding tissue were examined histologically.

The removal of residuals and oligomers from poly(2-hydroxyethylmethacrylate).

Poly(2-hydroxyethyl methacrylate) gels obtained by the cross-linking polymerization using four different free-radical initiators were washed with water. Chromatographically, the eluate appeared to be a mixture of low-molecular-weight compounds and of a small amount of the high-molecular-weight component. The UV and IR absorption spectra of compounds present in the eluate were compared with those of model compounds that were assumed to exist in the gel as impurities after the polymerization (monomers and oligomers of hydroxyethyl methacrylate, decomposition products of initiators).

Cisplatin-induced tubular injury studied by water-soluble synthetic polymers.

Accumulation of a synthetic water-soluble polymer, poly-alpha, beta-[N(2-hydroxyethyl)-D,L-aspartamide-co-N(4-hydroxyphenethyl )- D,L-aspartamide] in the cells of kidney proximal tubules was used as an indicator for the functional localization of Cisplatin (CDDP) induced tubular injury in rats. Tubular accumulation of polymer was examined using 131I and fluorescence labelling for quantitative as well as morphological evaluation. It was found that reabsorption of the polymer, in which mainly the epithelium of proximal convolutions is involved, remains unaffected upon CDDP treatment in the course of one to six days after the drug administration.

Evaluation of infusion sets by biological and chemical testing.

Some of the biological and chemical tests used in toxicological evaluation of synthetic polymers were correlated. The individual tests (sperm cell motility, tissue culture inhibition, intracutaneous test, optical absorption at 220-360 nm, reducing impurities) did not mutually correspond. The final estimation of the tested device is assessed as a sum of these units.

The use of 99Tc-pyrophosphate for imaging and measuring of calcification caused by implanted polymers.

Pyrophosphate labeled with 99Tc was evaluated as an indicator of the calcification which occurs after implantation of polymeric materials in rats. Poly(2-hydroxyethyl methacrylate), both porous and homogeneous, had been implanted. 99Tc pyrophosphate was applied intravenously to rats in intervals from 14 days to 15 months.

On the question of biological control methods for plastic materials.

Biological and chemical testing of plastic materials and devices needs the extraction of the analyzed sample. Polyamide was used as the model material and various effects of the extraction conditions on some biological (intracutaneous irritation, rat heart in situ, blood pressure on rats) and chemical (mass of the residue after evaporation) tests were studied. The material was extracted at 120, 55 and 37 degrees C for 0.