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  • Articles  (2,578)
  • Humans  (1,942)
  • Polymer and Materials Science  (636)
  • 1985-1989  (2,578)
  • Medicine  (2,578)
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  • Articles  (2,578)
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  • 1
    ISSN: 1432-0878
    Keywords: Skeletal muscles ; Ultrastructure ; Exercise ; Glycogen ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these “depleted” type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 161-178 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The patency of heparin-polyvinyl alcohol (hep-PVA) coated polyethylene tubing was found to be significantly longer than control tubes coated with polyvinyl alcohol (PVA) but without heparin at low flow rates in dogs using a novel parallel flow arteriovenous shunt designed to avoid surgical artifacts. A standard Silastic chronic shunt (3.18 mm i.d.) was inserted between the iliac artery and vein of a dog. After a 2-week recovery period, a small diameter coated polyethylene tube (1.14 mm i.d.) was connected in parallel with the exteriorized portion of the chronic shunt through a pair of Silastic Y-connectors, so that 〈3% of the shunt flow was diverted into the test tube. The chronic shunt was reused many times over a 〉6 month patency period, eliminating the need for frequent surgery and reducing interanimal variability in the results. The difference in patency between heparinized and control tubes was greater at higher mainshunt flow rates indicating the presence of a significant effect of the Y-connectors on platelet adhesion or aggregation. This effect was manifested in a time-dependent reduction in circulating platelet count. Scanning electron microscopy (SEM) examination of the midportion of the heparinized tubes after occlusion demonstrated the absence of platelet and fibrin deposits, unlike the control tubes without heparin. Although the Y-connectors played a significant role, they did not dominate the thrombotic processes occurring in this shunt and consequently the biological effectiveness of the immobilized heparin could be demonstrated.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 179-193 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As a series of studies on the mechanical properties of materials used in cardiac prostheses, static and dynamic characteristics and stability of five kinds of elastomeric polymers have been studied by uniaxial tensile and fatigue tests in air at room temperature and in saline solution at 37°C. Of all materials tested in this study, Texin MD85A, a segmented polyether polyurethane, has the lowest flexibility under static and dynamic conditions, with relatively high strength. Hexsyn, a polyolefin rubber, is highly flexible with little stress relaxation. However, this material has very low tensile strength and short elongation, and shows unstable change in the elastic modulus during cyclic deformation. Avcothane 51, a copolymer of polyurethane and silicon, has unstable mechanical properties and gradually stiffens upon cyclic deformation. On the other hand, Biomer, a segmented polyether polyurethane, has high flexibility and shows the most stable behavior during cyclic deformation regardless of test environment. Toyobo TM5, a similar segmented polyurethane to Biomer, has higher strength and ductility than Biomer, although its static and dynamic flexibility are slightly worse and less stable than those of Biomer. These results indicate that Biomer and Toyobo TM5 are more suitable for flexible components of cardiac prostheses.
    Additional Material: 9 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 197-198 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 241-250 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This is a review of the surface chemistry of bone mineral and its synthetic counterpart hydroxypapatite. Small-angle x-ray scattering and low-temperature nitrogen adsorption measurements show bone mineral surfaces range from 100 to 200 m2/g. The heats of adsorption of small molecules on bone and apatite surfaces show that these materials have polarizing surfaces which form strong bonds with polar and polarizable molecules. Water is hydrogen bonded to these surfaces with energies ranging from 23 Kcal/mol, for low coverage, to 11 Kcal/mol after two full layers; the latter value shows that after two monolayers the water is bonded as strongly to the solution as it is to the apatite surface. Stearic acid in cyclohexane adsorbs on bone and apatite surfaces in a closed-packed manner with the straight-chain molecules in parallel array with the end carboxyl groups hydrogen bonded to surface electronegative ions. Synthetic hydroxyapatite has long been used in chromatography because of the bonding capacity apatite surface has for certain proteins and polynucleotides. The metabolic interplay between bone mineral and the body results from the high magnitude and high reactivity of the mineral surface.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 615-629 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A radiation polymerized drug-vinyl copolymer delivery composite (0.8 mm in diameter, 3 mm long) was inserted into the right-lobe ventral prostate (I), into the right testis (II), and subcutaneously (III) into the back of male Wistar rats. The implantation was carried out over a period of 12 weeks maximum. From the relationship between the site of surgical insertion of the implant and the physiologic response (as measured by the decrease in the weight of the prostatic organs, e.g., ventral prostates, dorsolateral prostates, and seminal vesicles), it was found that in an AA560-containing composite (36 μg daily), the physiologic response is increased in order of (III) 〉 (II) 〉 (I). The same tendency was observed in the Estracyt-containing composite system (15 μg daily). The difference in the physiologic response owing to the site of surgical insertion of the implant was not observed in an E2-17β-containing composite (6 μg daily), although this composite showed the strongest physiologic response. No physiologic response in rats with CMA-containing composite (28 μg daily) was noted.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 991-1010 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 13 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 1031-1041 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was conducted to examine if an aminoglycoside (dibekacin sulfate, DKB) incorporated into a coating layer on outer and inner surface of indwelling catheters would be released into urine both in vitro and in clinical cases on a sustained basis and if the released DKB would have any efficacy on delaying lower urinary tract infections. Released amounts of DKB from the catheter silicone rubber (SR) catheter were periodically measured both in vitro and in clinical applications. During the clinical applications, the catheters were indwelled in 14 patients. Organism counts in the patients' urine were determined and organisms were isolated from bacteriuria (defined as ≧104 CFU/mL) and MICs to DKB were measured. Observations on several combined symptoms frequently associated with indwelling catherization were performed. Results showed that sustained release of DKB continued for more than 25 days and 13 days in vitro and in clinical cases, respectively. Clinical studies suggested that 8 days of sterile urine after catherization might be expected in patients without systemic administration of antibiotics and more than 2 weeks if combined with it. No particular problems in its use and associated symptoms were recognized.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 1073-1084 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The electrochemical behavior of aluminum in isotonic saline solutions, citrated human plasma, and citrated human blood is studied using potentiostatic and potentiodynamic polarization techniques complemented with scanning electron microscopy (SEM) and dispersive x-ray analysis. The effect of corrosion products on plasmatic proteins is investigated using electron microprobe analysis and immunoelectrophoresis analysis. Electrochemical data show a breakdown of the protective film on aluminium, due to the action of chloride, leading to the pitting of the metal. During pitting, the interaction of aluminium ion and the plasma proteins produces a nonadherent precipitate. Strong protein denaturation can be observed by immunoelectrophoresis of the precipitate suspended in physiologic solutions. The convenience of using organic fluids in addition to saline solutions to evaluate in vitro the behavior of metal for implants is suggested.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 1101-1115 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macrophage adhesion to a wide variety of substrates has been measured, but no systematic study of the influence of specific substrate chemical properties on adhesion is available. These studies were conducted using two series of materials, copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) and copolymers of hydroxystyrene and styrene, to determine the effect of a single chemical property, polar character, on adhesion. Rat periotoneal macrophages were allowed to contact polymer substrates for periods ranging from 1 to 240 min before being subjected to a shear stress of 60-120 dynes/cm2 in a thin-channel flow cell. Percentage adhesion was calculated from the number of cells that remained adherent to the substrate after 30 s of applied shear stress. Macrophages remained adherent to 100% EMA and all hydroxystyrene-styrene copolymer surfaces after only 1 min of contact. In copolymers of the HEMA-EMA series, the time required to attain peak adhesion levels increased with increasing substrate hydrophilicity (increasing HEMA content). Cells did not attach to the 20% EMA/80% HEMA copolymer and the 100% HEMA polymer. The results demonstrate that there is a time delay between contact and adhesion of the cells to surfaces of increasing hydrophilicity within the HEMA-EMA series and no time delay with the hydroxystyrene-styrene series. The time delay is thought to be a function of the excluded volume provided by polymers that are able to undergo significant chain rotation and or swelling in the solvent, water. Small excluded volumes present in copolymers of high EMA content and all hydroxystyrene-styrene copolymers offer little or no resistance to formation of adhesive bonds by macrophages, whereas copolymers with large excluded volumes (high HEMA content) prevent contact and/or adhesion. A mechanism based on the net excluded volumes of both the cell and substrate surface macromolecule is proposed to explain this phenomenon.
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