摘要:

Blood platelet retention on polyamine-graft-poly(2-hydroxyethyl methacrylate) (PHEMA) copolymer (HA) surface was investigated, focusing on pH and ionic strength of the surrounding medium to elucidate the nature of ionic interaction between platelets and HA copolymer surfaces. The conformational transition of polyamine graft chain in response to the protonation degree of amino groups was demonstrated to be an important factor influencing platelet retention on HA surfaces. When the polyamine graft chain exists in an extended conformation, protonated amino groups distribute from the matrix interface into the aqueous interior, resulting in the effective ionic interaction with platelets to increase their retention on HA copolymer surfaces. The number of protonated amino groups in polyamine portions crucially affected platelet retention. Worth noticing is that an introduction of a small but definite amount of cationic sites on the polymer surface led to significantly minimized platelet retention. It is considered that the surface property of PHEMA was drastically changed to a non-adhesive surface by introducing a small amount of protonated amino groups.

ISSN:0920-5063    

DOI:10.1163/156856292X00187

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

To understand how albumin on the surface inhibits surface-induced platelet activation, we adsorbed albumin on dimethyldichlorosilane-coated glass (DDS-glass) and modified the adsorbed albumin by three different methods. The adsorbed albumin was crosslinked with glutaraldehyde, dried and rehydrated, or digested with trypsin. Surface albumin concentration did not change by crosslinking; however, it decreased by about 15% by a simple dry-and-rehydration process. Trypsin digestion reduced the surface albumin concentration by 50%. Platelets were found to adhere and activate on albumin coated DDS-glass, if the adsorbed albumin was modified. The extent of platelet activation was quantified with two numeric parameters, the spread area and circularity. Fibrinogen adsorption to the dried or digested albumin layer resulted in enhancement of platelet activation, while adsorption of more albumin inhibited platelet activation. The results suggest that albumin can inhibit platelet activation as long as it covers the surface completely and remains flexible on the surface. This study indicates that steric repulsion is one of the mechanisms of surface passivation by albumin.

ISSN:0920-5063    

DOI:10.1163/156856292X00196

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Results are presented on kinetics of platelet accumulation in charged polyacrylonitrile (AN69) hollow fibers by continuous data recording under flow conditions (wall shear rate 108-1050 s-1), using suspensions of washed111In-labeled human platelets in Tyrode's-albumin buffer, containing washed red blood cells (0-40%). Preadsorption of a terpolymer of acrylonitrile, poly(ethyleneoxide) methacrylate and trimethylaminoethyl chloride methacrylate leads to very efficient passivation with respect to platelet accumulation and fibrinogen adsorption. In human ex vivo tests, evaluation of complement peptide C3a, platelet βthromboglobulin, leucocyte-polymorphonuclear neutrophile elastase and fibrinopeptide A shows no detectable activation. Furthermore, preadsorption appears to result in simultaneous improvement in hemocompatibility of the blood lines leading to and from the dialysis module. This single pretreatment of dialysis membranes should allow injection of lower doses of anticoagulant to patients submitted to hemodialysis.

ISSN:0920-5063    

DOI:10.1163/156856292X00204

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The adhesion and growth of two catheter-associated (O2K2 and O83K?) and two non catheter-associated (O111K58 and 0157K-) uropathogenic Escherichia coli strains on glass, poly(methyl methacrylate) (PMMA), a negatively charged copolymer of MMA and methacrylic acid (MAA) and a positively charged copolymer of MMA and trimethylaminoethyl methacrylate chloride (TMAEMA-Cl) were studied. The solid surfaces were placed in a parallel plate perfusion system. After preadhesion of the bacteria onto the surfaces, growth was initiated by perfusing the system with MacConkey broth. Growth was measured by counting adherent bacteria as a function of time. Bacterial strains were characterized by means of water contact angle, microbial adhesion to hydrocarbon (MATH), anion exchange resin retention (ARR) and zeta potential measurements. Solid surfaces were characterized by means of water contact angle and zeta potential measurements. The catheter-associated strains had significantly higher water contact angles, zeta potentials and ARR values than the non catheter-associated strains. Non catheter-associated strains did not grow at the surfaces used. Catheter-associated strains did not grow at the positively charged surface but exhibited growth at the other surfaces. Strains grew more rapidly at surfaces with a relatively high negative zeta potential and a low water contact angle than at surfaces with a relatively low negative zeta potential and a high water contact angle. The growth of strain O2K2 on glass was significantly reduced when urine instead of MacConkey broth was used as perfusion medium.

ISSN:0920-5063    

DOI:10.1163/156856292X00213

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Studies were undertaken to determine the effectiveness of a copolymer composed of PVA-TEGDA (PolyVinyl Alcohol TriEthylene Glycol) as a plasma-cholesterol lowering procedure. For a comparative study, five dogs underwent plasmapheresis including the transfusion bag containing gel in the plasma line, while three control dogs underwent the same plasmapheresis without gel. Numerous biological determinations were performed firstly in whole blood circulation before and after treatment over 10 days, and secondly in plasma before and after LDL binding on the gel. In the whole blood circulation, the average significant depletion of cholesterol levels was 31-51% for treated, 0-16% for control dogs and the average significant depletion of LDL cholesterol was 26-75% for treated and 0-3% for control dogs. Gel was therefore able to bind 121-217 mg of total cholesterol and 34-70 mg of LDL cholesterol per gram of gel. Lipid and lipoprotein levels rebounded 3-4 days after treatment. Adverse effects were not observed during all plasmapheresis. No significant differences between control plasmapheresis and gel-plasmapheresis were obtained for blood cell counts while lengthened coagulation times were observed during 24 h. Complement was not significantly activated by the copolymer as shown by a same decreased activity in the blood stream of all dogs: in fact, CH 50 depletion in the gel incubated plasma was due to a protein adsorption on the hydrogel. This new approach for LDL apheresis appears to be a promising new technique.

ISSN:0920-5063    

DOI:10.1163/156856292X00222

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor