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Biomedical subjects

M Stol

Publications and source records attributed to M Stol.

At least 37 records · Page 2Linked to original sources
PubMed1988

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). The irritation effects were dependent on the concentrations of the irritating substances and also on the gel type. Solid discs made of the gels, washed to varying degrees of purity, were also implanted into rats. Tissue irritation, as well as some other biological responses, were followed in situ using the radioindicator and common histological techniques. The irritation effects were very mild (even with the unextracted gel material). A possible explanation for the events taking place at the site of implantation is presented.

Animals↗
PubMed1988

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. The degree of irritation was dose dependent. In the concentration range 0-10%, the response was exponential. Model decomposition products derived from three different polymerization initiators were also tested. How the results obtained with the model irritants relate to real polymerization systems is discussed.

Animals↗
PubMed1987

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 degree of calcification of the implants was dependent on the collagen content; it was more pronounced with a higher amount of collagen. The composites with 30% (w/w) or more collagen were biodegraded during the long-term implantation. It is suggested that the composites containing less than 20% (w/w) of fibrillar collagen are used for biomedical applications and that those with a higher collagen content for the in vitro studies.

Animals↗
PubMed1985

Poly(2-hydroxyethyl methacrylate)--collagen composites which promote muscle cell differentiation in vitro.

A new simple method has been developed which allows the mixing of poly(2-hydroxyethyl methacrylate)--polyHEMA--and fibrillar collagen in any desired ratio. PolyHEMA alone was shown to be an unsuitable cultivation substrate for primary cultures of chicken embryonic skeletal muscle cells. Composites containing polyHEMA and 50% (w/w) or more collagen supported myogenesis. Such layers, firmly adhered to the bottom of plastic Petri dishes, were mechanically stable and biologically active, thus favourably combining properties of both the original materials. It is suggested that polyHEMA-collagen composite layers may be used for cultivation of differentiating cells in vitro.

Animals↗
PubMed1981

Mechanical properties of model synthetic tendons.

Model synthetic tendons consisting of 20 vol % of texturized poly(ethylene terephthalate) fibers and of the water-swollen poly(2-hydroxyethyl methacrylate) matrix have the tensile modulus E = 1.5 +/- 0.1 GPa, strength and strain-at-break sigma b = 85 +/- 10 MPa and epsilon b = 0.08 +/- 0.02. The force required for breaking tendons with the diameters 2, 3, 4 mm is, respectively, 300, 500, and 960 N. By these properties model synthetic tendons closely imitate the properties of natural tendons. Long-term (100 min) and repeated short-term (30 times 1 min) creep shows that on loading model tendons lose some 10% of their stiffness, but that the whole deformation is reversible. The shape of the compliance vs. time dependence of synthetic tendons closely resembles the dependence determined for the parent fiber. The stiffness and strength of a tendon are given by those of the fiber bundle used; by varying fiber volume fraction, it is possible to adjust the required mechanical properties of tendons.

Animals↗