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PubMedDate not supplied

[The use of ion-selective field transistors (ISFT) with photopolymerizable polyurethane membranes in nephrology for determination of potassium concentration (activity)].

The applicability is examined of ion selective field transistors with photocurable polyurethane membranes to control of the electrolytic composition of dialyzing solutions used in artificial kidney apparatus, and also of plasma in patient treated by chronic hemodialysis. The short- and long-time characteristics of the efficiency of K(+)-selective field transistors in continuous contact with solutions. Comparative testing of such transistors and other sensing systems is made. It is demonstrated that a sufficient reliability of measurements in the range of physiological concentrations in combination with low cost provide the possibility of using K(+)-selective field transistors for monitoring of the potassium concentration both in dialyzing solutions and plasma in patients on chronic hemodialysis treatment.

Humans↗
PubMedDate not supplied

Polyurethane-covered Wallstents to recanalize Wallstents obstructed by tumor ingrowth from malignant common bile duct obstruction.

Four patients with malignant obstruction of the common bile duct had been treated with uncovered Wallstents and suffered from a reobstruction after 2-13 months (mean 5.3 months). Repeat cholangiography revealed severe stenosis of the stent lumen caused by tumor ingrowth through the mesh. A Wallstent with a self-made polyurethane-cover was inserted through the uncovered stent in these patients. The four patients were followed for 3-13 months (mean 6.3 months) until death. There was good drainage with no evidence of recurrent obstruction in all patients. We conclude that a covered Wallstent may extend patency of stented bile ducts, preventing tumor ingrowth in patients with neoplastic obstruction. Further observations are needed.

Aged↗
PubMedDate not supplied

[The development of a process for culturing Bordetella pertussis immobilized on a polyurethane carrier].

The processes of the cultivation of Bordetella pertussis, immobilized on polyurethane carrier in a fermenter, were carried out and studied. Acellular pertussis preparations were produced from the culture fluid obtained in the batch and multi-cycle cultivation processes with immobilized cells, as well as in the process with interrupted fermentation (for confirming the possibility of the preservation of cell viability). The content of protein and B. pertussis toxin in these preparations, as well as their leukocytes-stimulating and hemagglutinating activity, did not differ from similar characteristics of preparations obtained from culture fluid in homogeneous cultivation.

Bacteriological Techniques↗
PubMed2000

Development of a hybrid artificial liver using a polyurethane foam/hepatocyte-spheroid packed-bed module.

Primary dog hepatocytes spontaneously formed spheroids in the pores of polyurethane foam (PUF) within 1-2 days of stationary culture. The spheroids, about 100-150 microm in diameter, partly attached to the surface and immobilized inside these pores. The lidocaine disappearance rate decreased to about 4 microg/10(5) viable cells/day for 10 days, while in the PUF/spheroid culture the rate was maintained at almost the initial level of 8 microg/10(5) viable cells/day for 10 days. Then, two scales of PUF packed-bed modules were designed. A small module (PUF volume; 14.5 cm3) was used for in vitro culture to investigate optimum culture conditions, and a large module (PUF volume; 300 cm3) was designed for dog experiments. Hepatocytes inoculated in these modules also formed spheroids and maintained almost the same activity of albumin secretion rate (111 microg/cm3 PUF/day in the small module and 87.7 microg/cm3 PUF/day in the large module). These results indicate that the PUF packed-bed module containing hepatocyte-spheroids is promising as a hybrid artificial liver.

Albumins↗
PubMed2001

The efficacy of nafamostat mesilate on the performance of a hybrid-artificial liver using a polyurethane foam/porcine hepatocyte spheroid culture system in human plasma.

Nafamostat mesilate (FUT) is a protease inhibitor of complement activation. The present study investigates whether FUT protects porcine hepatocytes from being injured by human plasma in a multi-capillary polyurethane foam packed-bed culture system (MC-PUF) such as the hybrid-artificial liver (PUF-HAL). Human plasmas with 1 mM of added ammonia were perfused using a small-scale PUF-HAL with porcine hepatocytes. FUT was continuously infused (10 microg/ml, 50 microg/ml). The ammonia detoxification was maintained in human plasma for 24 hours and for 48 hours with FUT which suppressed the rapid increase of asparaginic acid aminotransferase (AST) and alanine aminotransferase (ALT). After 60 hours of perfusion, hepatocyte spheroids completely collapsed in the human plasma, but a small amount of hepatocyte spheroid was maintained by FUT. The effect of FUT was slightly greater at 50 microg/ml than at 10 microg/ml. Our results suggest that FUT has protective effects against porcine hepatocytes in human plasma, and our PUF-HAL using porcine hepatocytes can function in human plasma for about 48 hours with FUT.

Alanine Transaminase↗
PubMed2000

Evaluation of the healing process after implantation of synthetic material called Tegmentum consisting of polyester mesh covered with polyurethane in rat peritoneum.

Polyester meshes are one of the synthetic prosthetic materials widely applied for the reconstruction of abdominal layers in child and neonatal surgery, cardiosurgery or vascular surgery. Because of the lack or insufficiency of the own, natural material multiple researches are performed in order to find the best material able to replace natural tissue. The most suitable prosthesis ought to be: sterile, non-toxic, soft, flexible, elastic, not very stretchy, durable, easy to operate (cutting, suturing); to create desired shape required while reconstracting, totally resistant to contagion, without any complication after being implanted. Since early seventies many scientists following above requirements have carried out researches to create the most similar prosthesis morphologically and functionally to human tissue but still there is no such an ideal material on the market. Polyester with its derivatives is one of the most commonly applied synthetic substances in surgery. The type of biomaterial highly depends on its purpose e.g.: for vascular prosthesis materials that are resorptive in organism and support tightness (gelatine, albumin, collagen); while for temporal replacement abdominal layers with prosthesis the most suitable is impervious to systemic fluids bacteria etc material, that prevents penetrating the surface of prosthesis by surrounding tissues, adhesions with intestinum or other organs. Tegmentum is a material that posses these features. This is a polyester mesh covered with polyurethane on one side produced by Tricomed S.A. (Łódź). Tegmentum has already been applied to neonates with congenital eventration in Child and Neonatal Ward in the "Szpital Pomnik Matki Polki" hospital in Łódź.

Animals↗
PubMed2001

Modeling the interactions between a prosthetic socket, polyurethane liners and the residual limb in transtibial amputees using non-linear finite element analysis.

Continuing earlier studies into the relationship between the residual limb, liner and socket in transtibial amputees, we describe a geometrically accurate non-linear model simulating the donning of a liner and then a socket. The socket is rigid and rectified and the liner is a polyurethane geltype which is accurately described using non-linear (Mooney-Rivlin) material properties. The soft tissue of the residual limb is modelled as homogeneous, non-linear and hyperelastic and the bone structure within the residual limb is taken as rigid. The work gives an indication of how the stress induced by the process of donning the rigid socket is redistributed by the liner. Ultimately we hope to understand how the liner design might be modified to reduce discomfort. The ANSYS finite element code, version 5.6 is used.

Amputation Stumps↗
PubMed2001

Fire and ecotoxicological aspects of polyurethane rigid foam.

The main characteristics of fire effluents from polyurethane (PUR) foams are comparable to those from natural materials like wood, cork, or wool. This similarity has been demonstrated by comparative data from analytical and toxicological studies. It is therefore presumed that effluents of these materials present similar hazards to human beings and the environment. In almost all fires, dioxins can be found in the smoke and residues. In fires involving PURs, relevant quantities of halogenated dioxins or furans are not to be expected; this has been confirmed by investigations under controlled laboratory conditions. The insulation properties of rigid PUR foam contribute significantly to environmental protection and the conservation of resources. A number of methods for reusing and recycling PUR rigid foam waste have been developed and realized in practise. The possibilities range from reusing the material itself, generating liquid raw materials, and thermal recycling, even for (H)CFC-containing PUR rigid foams, by cocombustion in suitable plants.

Conservation of Natural Resources↗
PubMedDate not supplied

[Physical development and health of children of polyurethane foam plant workers].

The paper presents data on poor working conditions at the foam polyurethane (FPU) plant, which cause specific clinical manifestations in workers, indirectly exert their children's health. The children of FPU plant workers have lower physical development, diseases of immune genesis (glumeronephritis, bronchial asthma, allergic manifestations, etc.) more frequently, higher incidence of dental caries, enamel hypoplasia in the presence of altered mineral metabolism.

Adolescent↗
PubMed1985

Elimination of toxicity from polyurethane foam plugs used for plant culture.

Polyurethane foam plugs commonly are used as collars or supports to grow plants in solution culture. Despite their utility, these foam plugs can be quite toxic to plants, particularly to small seedlings. We have observed tissue injury in tests using plugs to support lettuce, red beet, and potato plants in solution culture. Typically, the injury is initiated on the hypocotyl or stem tissue in direct contact with the foam, and appears within 30 hr as a brownish discoloration on the tissue surface. This discoloration can be followed by complete collapse of affected tissue and eventual death of the seedling. When injury does not progress beyond surface browning, the seedling survives but growth is slowed. In this paper, we report on different treatments that can be used to remove the toxicity of these plugs so they can be used in plant research.

Acetone↗
PubMed2001

[Study on preparation and properties of moisture permeable polyurethane membrane used for dressings].

A new hydrophilic polyurethane(PU) performed-polymer has been developed with polyethylene glycol(PEG) instead of general polyether. The solution of performed-polymer is poured casting a permeable membrane used for the outer layer of the bilayer dressings. The effects of molecular weigh (Mn) of PEG, the usage of cross-link agents, solvents and water in the solution on the moisture permeation of PU membrane have been studied. It has been shown that the membrane prepared is a porous moisture permeable membrane. The optimum conditions of preparing membrane are: Mn of PEG is 2,000-4,000, the mixture of acetone and N,N-dimethylformamide (DMF) is used as solvents, and the temperature of performance membrane is 50 degrees C-80 degrees C. The moisture permeability of the PU membrane is 49-60 g/m2.h at 35 degrees C, which can meet the requirement of the wound dressings. In addition, the mechanism of the moisture permeation of PU membrane has been discussed.

Bandages↗
PubMed2001

Polyurethane foam/spheroid culture system using human hepatoblastoma cell line (Hep G2) as a possible new hybrid artificial liver.

The risk of xenozoonosis infections poses the greatest obstacle against the clinical application of hybrid artificial liver support system (HALSS). Primary human hepatocytes are an ideal source for HALSS, but the shortage of human livers available for hepatocyte isolation limits this modality. To resolve this issue, we used human hepatocytes with replication capacity (fetal hepatocytes, Hep G2, and Huh 7) in a polyurethane foam (PUF)/spheroid culture system in vitro, and analyzed liver functions such as ammonia removal and albumin synthesis capacity; results were compared to those of porcine hepatocytes. Human fetal hepatocytes, Hep G2, and Huh 7 formed spheroids spontaneously within 24 h in a PUF/spheroid culture system; ammonia removal activity (micromol/10(6) nuclei/h) was upregulated, as was albumin synthesis activity (microg/10(6) nuclei/day). In particular, Hep G2 spheroids demonstrated high ammonia removal and albumin synthesis activities: 85% of the ammonia removal activity and 171.7% of the albumin synthesis activity of porcine hepatocytes in the monolayer culture. These results indicate the possibility of the development of a multicapillary PUF (MC-PUF) packed-bed culture system of hepatocyte spheroids as a HALSS using Hep G2.

Albumins↗
PubMed2002

[Current problems of occupational health in polyurethane production].

Prospective production of polyurethane is not safe for humans. This production is characterized by possible workers' exposure to chemical hazards mixture. The work safety includes cautionary and current sanitary supervision, implantation of sanitary recommendations concerning individual protective means also.

Adult↗
PubMed2002

[Study on blood compatibility of polyurethanes for catheters].

In this article, the blood compatibility of polyurethanes (PUs) made by ourselves for catheters is studied by hemolysis test, platelets adhesion test, kinetic thrombus time test and dynamic clot formation. The results showed that these PUs all have excellent blood compatibility. Among these PUs, H50-100 and H60-100 have best blood compatibility. Additionally, the relationship between the structure and blood compatibility is discussed.

Animals↗
PubMedDate not supplied

[Immobilization of trypsin on polyurethane matrix].

A method is developed to bind trypsin with the polyurethane matrix. At the first stage the reaction between trypsin and toluylendiisocyanate (TD1) was performed. At the second stage polyisocyanate obtained on the base of TDI-trypsin was sewn with polyoxypropylene glycol with a molecular weight of 1500. 2,4,6-Tris(dimethylaminomethyl)phenol served as an accelerator of the reaction. The polymer obtained is fine-porous and high-elastic. The chemical interaction of trypsin with the polymer is confirmed by the method of IR-spectroscopy and a decrease in the amount of free isocyanate groups. It is shown that the enzymic activity of trypsin chemically bound with the polymer is preserved at a room temperature for several months. When the polymeric net is formed from macrodiisocyanate in the presence of trypsin under conditions when the chemical interaction between the polymer and enzyme activity is also preserved, its value in this case being dependent on the relative content of the enzyme in the polymer -- it is higher in the case when the relative content of the enzyme is less, that may indicate the role of the polymer as a heterogenic cocatalyst or activator. The value of the proteolytic activity of the polymer with the chemically added trypsin is practically constant with its washing off in the column for 24h with 0,05 M veronal buffer whereas under these conditions the polymer with "free" trypsin loses completely the enzymic activity.

Binding Sites↗
PubMed2002

High metabolic function of primary human and porcine hepatocytes in a polyurethane foam/spheroid culture system in plasma from patients with fulminant hepatic failure.

It has been demonstrated that plasma from patients with fulminant hepatic failure (FHF) interferes extensively with cellular function. We placed primary human and primary porcine hepatocytes in a polyurethane foam (PUF)/spheroid culture system and compared the metabolic functions in the plasma of patients with FHF in a 24-h stationary culture to those in a monolayer culture. The PUF/spheroid culture system using primary human and primary porcine hepatocytes significantly decreased ammonia content during 28-day culture. Fisher's ratio significantly increased at culture days 3 and 7. Tauroursodeoxycholic acid significantly increased and glycochenodeoxycholic acid and taurochenodeoxycholic acid decreased in the FHF patients' plasma at culture day 3. During at least a 24-h culture in the FHF patients' plasma, metabolic functions of primary human and primary porcine hepatocytes were almost identical. The present results indicate that the PUF/spheroid culture system using primary human or primary porcine hepatocytes demonstrated more advantageous metabolic functions in the plasma from patients with FHF than the monolayer culture.

Ammonia↗