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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 216 (1967), S. 1011-1013 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In four male Wistar rats each weighing 230 g the left kidney was ligatured to cut off completely its blood supply. In two of the rats the kidney was removed for examination after 6 days and in the other two after 30 days. The calcium content was assessed in each case as follows. The kidney was ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 13 (1973), S. 63-72 
    ISSN: 1432-0827
    Keywords: Structure ; Poly(glycol monomethacrylate) ; Gel ; Implants ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Abstract L'effet de la structure physique et des modification chimiques de gels de poly(glycol monométhacrylate) sur la calcification d'implants tests a été étudié. Alors que les modifications chimiques du poly(glycol monométhacrylate) osseux, obtenu par introduction de groupes formateurs d'ions, n'affectent pas le processus de calcification, on observe un effet net de la structure physique du polymère par action du rapport monomère: eau sur le processus de calcification des implants. Des gels homogènes et microporeux montrent rarement une calcification autor de l'implant; dans les gels macroporeux, la calcification s'observe massivement autour de l'implant, en cas de porosité élevée en son centre. Ce phénomène a été expliqué par la pénétration diverse par du tissu néoformé ainsi que par la possibilité de pénétration d'éléments nutritifs cellulaires, liée à la porosité de l'implant.
    Abstract: Zusammenfassung Die Wirkung der physikalischen Struktur und der chemischen Veränderung von Poly-(Glycol-Monomethacrylat)-Gelen auf die Verkalkung von Implantat-Proben wurde untersucht. Die chemische Veränderung der Poly(Glycol-Monomethacrylat)-Grundstruktur, hervorgerufen durch das Beifügen ionogener Gruppen, hatte auf den Verkalkungsprozeß keine Wirkung; die physikalische Struktur des Polymers hingegen hatte eine markante Wirkung auf den Verkalkungsprozeß der Implantate, welche durch das Verhältnis Monomer: Wasser bestimmt wurde. Homogene und kleinporöse Gele zeigten ganz ausnahmsweise eine Verkalkung am Rande des Implantats; in großporösen Gelen erfolgte massive Verkalkung am Rande des Implantats, bei höherer Porosität in dessen Zentrum. Dieses Phänomen wird zurückgeführt auf den unterschiedlichen Grad, in welchem das neu gebildete Gewebe das Implantat durchdringt und auf die verschiedene Zugänglichkeit der Nahrung der eindringenden Zellen, welche von der Porosität des Implantats abhängt.
    Notes: Abstract The effect of the physical structure and chemical modification of poly(glycol monomethacrylate) gels on the calcification of test implants has been studied. While the chemical modification of the poly(glycol monomethacrylate) backbone by the introduction of ionogenic groups did not affect the process of calcification, there was a substantial effect of the physical structure of the polymer, as determined by the monomer: water ratio, on the process of calcification of the implants. Homogenous and microporous gels showed calcification in the margin of the implant only exceptionally; in macroporous gels calcification occurred massively in the margin of the implant and in the case of a higher porosity in its centre. This phenomenon has been explained by the different degree to which the implant is penetrated by the newly formed tissue, as well as by the difference in accessibility of nutrition to the penetrating cells depending on the porosity of the implant.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The elimination and retention of a new, fully synthetic plasma prosthesis of Czechoslovak origin under the working name of Duxon (poly[N-(2-hydroxypropyl)methacrylamide]) was investigated in experiments on rabbits by using a 14C-labeled polymer. Results published earlier on elimination have been confirmed and extended. Retention was examined after repeated application. The effect of molecular weight prevailed both in elimination and in retention. Polymers of lower molecular weights, which possess a good therapeutical effect, are not permanently deposited in the organism.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 723-730 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Pyrophosphate labeled with 99Tc was evaluated as an indicator of the calcification which occurs after implantation of polymeric materials in rats. Poly(2-hydroxyethyl methacrylate), both porous and homogeneous, had been implanted. 99Tc pyrophosphate was applied intravenously to rats in intervals from 14 days to 15 months. Scintigraphy, x-ray examination, and histology were carried out. The ratio of specific activity in the capsule around the implant to specific activity in the reference tissue was determined. The cumulation of activity was parallel with the development of calcification as revealed by histology. The method can be used not only in the screening test of new polymeric materials, but also in a quantitative determination of the degree of calcification in general.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 95-104 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biological compatibility of polypyrrolidone was investigated using subcutaneous implantation in rats. Acute (10 days) and chronic (360 days after implantation) tissue reaction was characterized numerically and compared with poly(2-hydroxyethyl methacrylate), used in the Drug Control Research Institute in Prague as a standard in the evaluation of polymers, for which good tolerance in the clinical practice has been demonstrated. Surface changes in the polymer were evaluated by using a scanning electron microscope.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 123-136 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The long-term biological tolerance of hydrophilic gels containing ionogenic groups was investigated on animals (rats and pigs). The basic polymeric skeletons of poly(glyco1 monomethacrylate) and poly (N-ethyl methacrylamide) were modified by introducing acidic (carboxylic) and basic (tert-amino) groups, or both groups at a time. Introduction of both groups at a time in the molar ratio yielded an electroneutral polymer of ionogenic character.In all groups investigated here the implant was encapsulated by a fine capsule of collagen fibrous tissue; no signs of proliferation were observed. No calcification took place.The second part of the work consisted in an investigation of the tolerance of heterogeneous poly(glyco1 monomethacrylate) gels containing ionogenic groups,basic, acidic, and ampholytic, with continuously changing porosity. The microporous polymers (50-60% water in the starting mixture) were healed-in as compact gels by encapsulation with collagen fibrous tissue. The macroporous polymers (70% of water and more in the starting mixture) were encapsulated with a capsule of collagen fibrous tissue, from which newly formed capillaries,serous exudate and numerous cells penetrated into the implant. The more porous the material, the broader the zone of cellulization. In microporous polymers there was no calcification; in macroporous, calcification occurred in the margin of the implant or in its center. In contrast with other authors' findings,no effect of the chemical composition within the concentration range investigated upon the way of healing-in or calcification could be observed; only the effect of physical factors was evident.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 5 (1971), S. 197-205 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Experiments were investigated on animals' biological tolerance of the copolymers of N-substituted methacrylamides with the monomers which can be considered for uses in the modification of the monomeric backbone. The group of N-substituted methacrylamides is the second one in the series of hydrophilic polymers arranged according to their increasing resistance to hydrolysis, and it follows immediately after the esters of methacrylic acid. Histological analysis has shown that the copolymer of N-ethyl methacrylamide with methyl methacrylate is the best tolerated polymer of this group. In the case of copolymers with butyl acrylate and butyl methacrylate, in the first days after implantation a stronger and more cellular capsula was formed, and an inflammation was observed in the surroundings of the encapsulated implant. Starting from day 30, however, no differences are found in the encapsulation, and the result of healingin of all the polymers is always favorable. No cancerogenic effects were observed; calcification was found only sporadically in the case of the copolymer with butyl methacrylate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The behavior of aqueous solutions of poly [N-(2-hydroxypropyl) methacrylamide], poly(N-ethyl methacrylamide), poly(N-ethyl acrylamide), and poly-(triethyleneglycol monomethacrylate) was investigated and characterized in tests required for synthetic infusion solutions. The above solutions were characterized from the viewpoint of toxicity, pyrogenic properties, antigenic properties, effect on the determination of the blood groups, and effects on hemocoagulation. The elimination from blood circulation was studied on several fractions of the 14C-labelled poly[N-(2-hydroxypropyl) methacrylamide] having different molecular weights. It was found that in all tests the properties of the polymers investigated do not depart from the expected behavior.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 5 (1971), S. 447-458 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Test implantations were carried out on rats in order to investigate the effects of porosity of heterogeneous poly(glycol monomethacrylate) gels on their healingin. The porosity was varied by changing the water content in initial monomeric mixture. The histological analysis has shown that spongy polymers containing 50 and 60% of water in the initial mixture are healed-in similarly to the homogeneous gel by encapsulation with collagen fibrous tissue. In polymers having higher content of water in the initial mixture, i.e. higher porosity, the vessels from the new formed fibrous capsula penetrate into the implant. The higher the porosity, the narrower the capsula and the broader the zone of cellulization and new-formed capillaries, penetrating into the implant. In the case of polymers of higher porosity, giant multinuclear cells are observed in the margin of the implant. The positive Kóssa's calcium reaction was found only sporadically on the margin of the implant.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 111-121 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biological tolerance of poly(N-substituted acrylamides) implanted subcutaneously to rats and pigs was investigated. Besides a macro- and microscopical evaluation of the implant and its surroundings, the surface changes of the implants were determined by means of a Stereoscan electron-optical microscope;the results obtained confirmed the very good in vivo stability of the polymers used.The histological analysis showed that all the polymers under investigation are very well tolerated by the organism and do not provoke any unfavorable reaction. The implants become surrounded with a granulation tissue which is gradually replaced by fibrocytes and collagen fibers situated in the basic substance staining positively with the alcian blue and PAS. In contrast with some authors we did not find a thicker capsule surrounding the implant on the sharp edges but on the flat planes. No calcification could be observed within the intervals investigated. The surface changes, which were studied electronoptically, were insignificant and connected with the way in which the implant was treated. No indications of malignant growth were observed.
    Additional Material: 6 Ill.
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