The biological assessment of the chitin fibres.

On the basis of carried laboratory tests of the aqueous extracts, such as pH evaluation, electric conductivity and dry residue assessment we can stated that the obtained results are within the limits of the standards and are comparable to these given for similar kinds of medical devices, e.g. for Dexon sutures: pH--6.10; electric conductivity--31 MicroScm-1; dry residue after evaporation--0.0014 g/100 cm3. The mean percentage of hemolysis counted from the three samples made for chitin extracts was 0.86% and did not exceed the value of 1% which is accepted by the standards. In the assessment of the cytotoxicity which was carried out on the mouse fibroblasts, the proper morphological character was stated. Agglutination, vacuolisation, nor cells membrane lysis were not observed. The number of cells separated from the matrix were identical as in the control cultures. The increased number of the dead cells and decreased proliferation of the cells in the cultures containing the chitin extracts, were probably due to the ethylene oxide residues, which was used for sterilisation of the fibres. The assessment of the intracutaneous reactivity of the chitin extracts showed the lack of the irritation influence and the index of primary irritation was of no importance at all. The pathomorphological findings, which included macroscopic and microscopic evaluation, specially carried out after the implantation, showed the greater biocompatibility of the tested chitin fibres in comparing them to the Maxon sutures. The healing process of these fibres included the short exudative phase, which was more significant than in Maxon sutures reaction followed by the proliferation phase, which ended with the development of the connective tissue capsule. The connective tissue penetrated among the single chitin fibres. After longer observation periods (more then 30 days) the thickness of the capsule decreased. The number of the chitin fibres did not change over the observations periods, however the change of the colour of the fibres was observed. In our opinion it is the sign that the process of resorption has already started. The tissue reactions after implantation of the chitin fibres can be compared to those observed for monofilament suture Maxon. On the basis of all these observations, assessments and findings we can stated that the chitin fibres fulfil the basic biological requirements set up for the bio-medical devices.

[Tissue reaction to implanted polyurethane designed for parts of the artificial heart]. / Odczyn tkanek na implantaty poliuretanowe przeznaczone na elementy sztucznego serca.

Experiments on producing polyurethane membranes which could be used for elements of an artificial heart have been carried out in Poland for several years. In the Institute of Biocybernetics and Biomedical Engineering PAN in Warsaw two kinds of polyurethanes with symbols PU 47 and PU 90 have been worked out. They differ in physicochemical properties and they were subjected to investigations of tissue reaction in the Institute of Experimental Surgery and of Biomaterials Investigations of the Medical Academy in Wroclaw. The investigations were carried out on 70 rats of the Wistar breed and on 30 rabbits of the New Zealand breed. Polyurethane circles were implanted into subcutaneous tissue, to peritoneal cavity and into muscles of the back in rats; polyurethane oars were implanted into muscles of the back along the backbone of the rabbits. Sections of the animals were carried out 3, 7, 14, 28, 90 and 180 days after the surgery taking 5 animals in each term. Macroscopic and microscopic as well as physicomechanical investigations were carried out. The carried out experimental investigations of the both kinds of polyurethanes showed good tolerance of the animals' organisms on the implanted material. Summing up, we can say that the tested polyurethane foils with symbols PU 47 and PU 90 satisfy the basic requirements made on the materials designed for temporal contact with a living organism.

[Experimental testing of hydrogel dressings POLGEL based on the basis of synthetic monomers]. / Badania doswiadczalne opatrunków hydrozelowych POLGEL opartych na bazie syntetycznych monomerów.

In the Department of Experimental Surgery and Biomaterials Research in Wroclow Medical Academy standard and qualifying evaluation of 5 kinds of hydrogel dressings POLGEL produced in the Institute of Physico-Chemistry and Technology of Polymers of produced in Silesian Polytechnique has been carried out. Dressings Polgel were obtained as a result of copolymerization of acrylamide and methylene-bis-acrylamide in aqueous solution. On the basis of introductory experiments for qualifying evaluation dressing Polgel M modified with glycerin in the form of foil and dressing Polgel T--in the form of jelly were chosen. Both kinds of dressings did not cause haemolytic, toxic or irritative effects. In pathomorphological experiments moderate tissues reaction was noticed what signifies good biological characteristics of the evaluated dressings. The process of healing of injuries treated with dressings Polgel M proceeded well and epidermis creating was quicker in comparison with injuries treated with traditional dressing. On the basis of the carried out experiments it was noticed that dressings Polgel M and T satisfy the requirements made for the type of materials.

[Attempts at modification of the polyester vascular prosthesis]. / Próby modyfikacji poliestrowych protez naczyniowych.

Polyester vascular bilaterally velour prostheses produced by the Enterprise of Medical Products TRICOMED in Lodz were modified through: putting negative electric charge on the internal surfaces of prostheses; additional cleaning with ethanol; covering of the surfaces of prostheses with silicone preparation; two-sided covering of the surfaces of prostheses with collagen by the radiative method; covering of the surfaces of prostheses with chitosane. Laboratory investigations, investigations of hemolytic and toxic effects of aqueous as well as experimental investigations has been carried on piglets. During these investigations it was observed that the carried preparations caused multiple increase of electrical conductivity of proper and dry remnant after evaporation of the aqueous extracts. Hemolytic and toxic effects were not observed. In radiological and pathomorphological investigations it was observed that none of the preparations used for modification of vascular prostheses influenced improvement of their biological properties. In comparison with the initial prostheses DALLONR these prostheses evoked a greater reaction of tissues which was manifested with a thick internal layer causing narrowing of the lumen of the section with prosthesis or closing it. A small improvement of the biological properties of the prostheses were achieved after cleaning them with methanol. However, this improvement is so small that it does not justify changes in the existing technology.

[Experimental studies of new Polish hydrogel dressing materials HDR]. / Badania doswiadczalne nowych polskich opatrunków hydrozelowych o symbolu HDR.

Recently the spectrum of dressings was enriched, incorporating the so-called hydrogel dressing, made by Geistlich Sons Ltd. and Byk Goldbin-Konstanz referred to as "Geliperm". In Poland, HDR hydrogel dressings' technology was launched by Institute of Radiative Technology, Lódz+ Polytechnic. This type of dressing is obtained by radiative cross-linking of hydrophilic polymers. The experimental studies of the new Polish hydrogel materials were accomplished at the Department of Experimental Surgery and Biomaterials Research, the Chair of traumatologic Surgery, Medical Academy of Wroclaw. These studies concerned three kinds of hydrogel dressings, different in composition and irradiation conditions. HDR-1 10% of polyvinylpyrrolidone+, 1.5% of agar, 1.5% of polyethylene glycol 300, irradiated with 30 kGy (gamma radiation of 60Co); HDR-1 with neomycin--formula as above plus neomycin sulfate (2.5%); HDR-2 6% of polyvinylpyrrolidone++, 1% of agar, 1.5% of polyethylene glycol 300, irradiated with 25-27 kGy (gamma radiation of 60Co). The usable properties of the HDR dressings approximate those of the West German products. Owing to the lab tests, biological and in vitro examinations we had performed, it was possible to state that aqueous extracts of the hydrogel dressings subjected to assessment did'nt exhibit hemolytical or toxic activities in cellular tests, at the same time lacking an irritating effect. They cause a minimal tissular reaction and accelerate the process of healing.

[Experimental testing of the hydrogel dressing Geliperm]. / Badania doswiadczalne hydrozelowego opatrunku Geliperm.

The dressing materials used in the local treatment for dressing large defects of skin, subcutaneous and muscular tissues do not have the optimum protective and therapeutic properties. We carry out experiments tending to achieve new kinds of dressing impermeable for microorganisms, free from toxic, allergic, action and acridity and not evoking pathological tissue reaction in a long-lasting contact with the wound. What is more, the new dressing should hasten the cicatrization process of a wound and enable its control as well as soothe the pain if it is possible. Some of these properties were achieved by the usage of cross-linked hydrophilic polymers with high ability of water absorption, creating elastic gels in its presence. The dressing of this type called Geliperm was produced by Geistlich Sons Ltd. and BYK Goldbin-Konstanz firms. The methods of evaluation of hydrogel dressing materials comprising a preliminary, standard and qualifying evaluation were worked out in the Department of Experimental Surgery and Biomaterials Research Medical Academy of Wroclaw. According to the worked out scheme of experiments the Geliperm dressing was evaluated. We have discovered on the basis of the carried out experiments that the new generation of gel dressing has, to a large extent, the properties of the so called "ideal dressing".

[Experimental studies of Gore-Tex prostheses. A review of the literature]. / Badania doswiadczalne protez Gore-Tex. Przeglad literatury.

The Gore-Tex prostheses, made of pure polytetrafluoroethylene (PTFE) by W. L. Gore and Associates (USA), were first described in 1972. The first published report included results of experimental studies and description of two clinical cases. In the following years (1973-1981) many varieties of the PTFE prostheses were made. Each time the prostheses were tested on laboratory animals (dogs, rabbits, rats). The prostheses were used in the arterial and the venous systems. Observations were carried out as long as to 6 months after operation. The degree of patency was in the range from 56 to 100%. All research were important in the evaluation of the new models of PTFE prostheses. However, studies on prostheses of the diameter more than 5 mm are lacking. The present article outlines and criticizes basic experimental studies, which added to the knowledge on PTFE prostheses of the Gore-Tex type, depending on their structure. Due to experimental studies the Gore-Tex prostheses are now widely applied in clinical treatment.