|
1. |
Study on antithrombogenicity of poiy[β-(acetytsalicylyloxy)ethyl methacrylate] relative to poly(hydroxyethyl methacrylate) |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 1-13
Hiroko Sato,
Jun-Ichi Kojima,
Akio Nakajima,
Takashi Morita,
Yasuharu Noishiki,
Zhong-Wei Gu,
Fu-Mian Li,
Xin-De Feng,
Preview
|
PDF (6597KB)
|
|
摘要:
The antithrombogenicity of a polymer made of aspirin bound to hydroxyethyl methacrylate (HEMA), abbreviated as ASA-polymer, was compared with that of poly(hydroxyethyl methacrylate) (PHEMA). Platelet from platelet rich plasma (PRP) incubated with ASA-polymer surface exhibited noticeable decreases in adhesion and aggregation as compared to platelets incubated with PHEMA. Low molecular weight components other than aspirin, which may be released from ASA-polymer during the incubation with PRP, or contact with ASA-polymer causing denaturation of platelets without morphological changes could be responsible for the decrease of adhesion and aggregation. Both PRP and PPP exposed to ASA-polymer-coated surfaces exhibited a much smaller partial thromboplastin time (PTT) than if exposed to PHEMA-coated surfaces; the PTT of ASA-polymer was similar to that of glass exposed plasma. With respect to the in vivo antithrombogenicity, the ASA-polymer surface led to thrombus formation. This may be due to the partial hydrolysis of the acetyl groups resulting in the formation of a negatively charged surface which in turn accelerates the coagulation cascade despite its inhibitory effects on platelet adhesion and aggregation. On the other hand, neointima formed around a thrombus layer on PHEMA-coated sutures after 14 days.
ISSN:0920-5063
DOI:10.1163/156856291X00016
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
2. |
A new in vitro thrombogenicity test for medical tubes |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 15-23
W. Lemm,
Preview
|
PDF (1070KB)
|
|
摘要:
Basic information on the affected coagulation behaviour of healthy human blood passing foreign artificial surfaces is of immense importance for a safe clinical therapy. An in vitro screening method is presented which tests the thrombogenicity of medical tubes, applying the clinically already established resonance thromobography (RTG). Several medical tubes with various types and contents of plasticizers are tested and compared with materials free of additives. The effect of the release of ingredients is indicated by this procedures, as well as the influence of a sterilizing treatment with gamma-radiation on the physical surface properties, such as smoothness. In all cases, the modified RTG method proves its suitability and sensitivity. In addition, this method allows accurate adjustment of the extrusion parameters for tube manufacturers.
ISSN:0920-5063
DOI:10.1163/156856291X00025
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
3. |
Interactions of functionalized polystyrene derivatives with the complement system in human serum |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 25-35
B. Montdargent,
D. Labarre,
M. Jozefowicz,
Preview
|
PDF (536KB)
|
|
摘要:
The interactions between blood and insoluble polysaccharidic surfaces result in activation of the immune system of complement. When substituted with carboxymethyl groups, Sephadex loses its capacity to activate complement, whereas Sephadex sulphate has been described as an activator. In order to elucidate the molecular mechanisms of complement activation and inhibition, a simpler polymer model has been choosen: it consists of an insoluble polystyrene backbone on which either isolated hydroxymethyl or sulphonate groups or both are present. The surfaces bearing the isolated groups consume complement but the mechanisms involved are quite different. In contrast, a surface bearing equal proportions of both types of groups is a non-activator. Such model surfaces can be very useful for designing artificial surfaces able to control in situ complement activation.
ISSN:0920-5063
DOI:10.1163/156856291X00034
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
4. |
Influence of molecular structure on the synergistic action of theophylline or dipyridamole derivatives in the prostaglandin-type inhibition of platelet aggregation |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 37-52
C.H. Bamford,
I.P. Middleton,
K.G. Al-Lamee,
Preview
|
PDF (1778KB)
|
|
摘要:
Approximately 30 new derivatives of theophylline and dipyridamole have been prepared and examined as potentiators of the inhibition of platelet aggregation induced by the prostaglandin analogue BW 245C. Potentiating activity has been found to be sensitive to molecular size and also to the presence of specific groups. Polymeric adducts based on dextran, poly(ethylene glycol) or poly(N-vinyl pyrrolidone), and aliphatic esters with alkyl chain-lengths greater than 7 are inactive in potentiation. Derivatives containing carboxyl groups are also inactive. Potentiation is discussed in terms of platelet membrane penetration and extra- and intra-cellular processes. The latter are invoked to account for the enhanced potentiation shown by dipyridamole and derivatives when aggregation is induced by PAF-acether rather than ADP. One derivative of particular interest is the adduct of theophylline with 1,2,5,6-diisopropylidene-D-glucose, containing a furanose ring. This is a more active potentiator than theophylline itself, possibly owing to its molecular resemblance to cAMP. On conversion to the pyranose form all activity is removed.
ISSN:0920-5063
DOI:10.1163/156856291X00043
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
5. |
Effect of particle size on phagocytosis of latex particles by guinea-pig polymorphonuclear leucocytes |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 53-60
Yasuhiro Ishikawa,
Nobuhiro Muramatsu,
Hiroyuki Ohshima,
Tamotsu Kondo,
Preview
|
PDF (368KB)
|
|
摘要:
The effect of the size of foreign particles on phagocytosis by guinea-pig polymorphonuclear leucocytes (PMNs) was investigated using latex particles having approximately the same surface potentials but different sizes. Two types of latexes with different negative surface potentials, those having amino groups (Ami-latexes) and those having carboxylic acid groups (Ca-latexes), were used in this experiment. Since Ca-latexes had different surface potentials for different particle sizes, the carboxylic acid groups were modified by the carbodiimide method to make the surface potentials almost equal. Phagocytosis was estimated by the rate of oxygen consumption. It was found that the phagocytosis reached its maximum when the latex particle size was about 0.5 μm. This finding was plausibly explained by considering the two probabilities that a latex particle comes into contact with a PMN surpassing a potential barrier and the contact takes place at certain receptor areas favourable to phagocytosis on the PMN surface.
ISSN:0920-5063
DOI:10.1163/156856291X00052
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
6. |
Selective synthesis of 2,4-bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine as a protein modifier |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 61-65
Kechi Ono,
Yoshiyuki Kai,
Hiroo Maeda,
Fumio Samizo,
Katsukiyo Sakurai,
Hiroyuki Nishimura,
Yuji Inada,
Preview
|
PDF (199KB)
|
|
摘要:
2,4-Bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine, a protein modifier with two polyethylene glycol chains (activated PEG2) was synthesized from monomethoxypolyethylene glycol and cyanuric chloride using zinc oxide as a catalyst by the improved method of a previous study (Matsushima et al., Chem. Lett. 7, 773, 1980). The product was identified as activated PEG2without contamination of by-products with chromatographic and structural analysis.
ISSN:0920-5063
DOI:10.1163/156856291X00061
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
7. |
In vitro evaluation of an epoxy resin's cytocompatibility using cell lines and human differentiated cells |
|
Journal of Biomaterials Science, Polymer Edition,
Volume 2,
Issue 1,
1991,
Page 67-79
M.-F. Harmand,
L. Bordenave,
R. Bareille,
A. Naji,
R. Jeandot,
F. Rouais,
D. Ducassou,
Preview
|
PDF (3752KB)
|
|
摘要:
The cytocompatibility of a polyepoxy resin (Elf Aquitaine) has been studied using both cell lines and human differentiated cell cultures. The human models were gingival fibroblasts and bone osteoblasts, while the cell lines were Hela cells and 3T3 Ba1b/c cells. Basal cytocompatibility was assessed by estimation of the cell proliferation, total cell protein content, cell membrane sub-lysis, and cell attachment and spreading. Specific cytocompatibility concerning human osteoblasts, from both alveolar and trabecular bone, was determined by measuring the intracellular alkaline phosphatase activity. Resin colonization by the cells was studied by both TEM and SEM. The behaviour of the two cell lines reveals a significant level of discrepancy, whereas the behaviour of human cells, whatever the model, is comparable; however, osteoblasts look more sensitive. Moreover, the results show that this epoxy resin exhibits a moderate cytocompatibility which could be the result of the cytotoxicity of early released products, associated with the considerable surface roughness.
ISSN:0920-5063
DOI:10.1163/156856291X00070
出版商:Taylor & Francis Group
年代:1991
数据来源: Taylor
|
|