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  • Polymer and Materials Science  (7)
  • Electron microscopy  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 99 (2000), S. 39-47 
    ISSN: 1432-0533
    Keywords: Key words Sural nerve ; Muscle fiber diameter ; Morphometry ; Electron microscopy ; Myotonic ¶dystrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We compared peripheral nerve fibers and muscle fibers in myotonic dystrophy (MD) using a computer-assisted device for morphometry. In the 17 cases with MD studied, the sural nerves of 14 cases (82%) showed various degrees of reduction of the myelin sheath area (MSA) per endoneurial area. Of these, 8 cases (47%) presented with a mild reduction of the MSA, 5 cases (29.4%) with moderate reduction, and one case (6%) with severe reduction. The number of myelinated nerve fibers was not significantly reduced in MD when compared with control nerves, due to clusters of small regenerated nerve fibers. The mean diameter of the muscle fibers in 6 of the 17 cases was less than 40 μm. Of these 6 severely affected cases, ¶5 revealed a considerable reduction of the MSA. Other cases, which appeared to be normal in respect to the diameter of muscle fibers, showed various degrees of reduction of the MSA. Thus, there is usually, but not always a morphometric correlation of the severity of changes between peripheral nerves and muscle. The severity of the peripheral neuropathy appears to depend largely on the patient’s age, the stage of the disorder, and the time of progression. Electron microscopic examination of sural nerves showed significant, though non-specific pathological changes.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 218-241 
    ISSN: 1432-0533
    Keywords: Myotonic dystrophy ; Sarcoplasmic masses ; Striated annulets (Ringbinden) ; Muscle fiber ; Electron microscopy ; Phase microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Biopsiematerial von drei Patienten mit unterschiedlichen klinischen und pathologischen Stadien der myotonischen Dystrophie wurde phasenkontrast-und elektronenmikroskopisch untersucht. Beim 1. und 2. Fall waren “sarkoplasmatische Massen” und “Ringbinden” besonders zahlreich, während sie beim 3. Fall mit klinisch erheblich fortgeschrittener Muskelatrophie nur ausnahmsweise vorkamen. Elektronenmikroskopisch erschienen fast alle Elemente der Muskelfasern, zumindest an einigen Stellen, von dem atrophischen oder dystrophischen Prozeß betroffen: Myofilamente, Z-Streifen, Triaden, Kerne, Mitochondrien und Sarkolemm. Außerdem fanden sich cytoplasmatische Cysten, multilamellierte Körperchen, zahlreiche Lipofuscingranula und verschiedene andere abnorme Strukturen. Besonders kennzeichnend für die Erkrankung waren die “sarkoplasmatischen Massen”, die mit variablen Mengen von fehlorientierten Myofilamenten, aber auch von anderen Komponenten der Muskelzelle ausgefüllt waren. Die Ringbinden wurden von fehlorientierten Myofibrillen gebildet, indem sie meist kreisförmig die im Zentrum normal ausgerichteten Myofibrillen umschlossen. Einzelne Veränderungen, die bisher weder bei der myotonischen Dystrophie noch in irgendeiner anderen Muskelkrankheit nachgewiesen worden sind, konnten in leicht dystrophischen wie auch in hochgradig atrophischen Fasern nachgewiesen und identifiziert werden: Große homogene Lacunen, die sich vom sarkoplasmatischen Reticulum herleiten und eigenartige geometrische Anordnungen der terminalen Cisternen. Der Ursprung bestimmter anderer Strukturen blieb unklar. In unserem Material fanden sich keine segmentalen Nekrosen, so daß sich die Relation des dystrophischen Prozesses zur Zenkerschen Degeneration und zur Atrophie, den nach histologischen Untersuchungen wesentlichsten Befunden bei der Steinertschen Erkrankung, nicht eindeutig bestimmen ließ.
    Notes: Summary Biopsies from three patients with different clinical and pathological stages of myotonic dystrophy were studied by phase and electron microscopy. Large sarcoplasmic masses and spiral annulets were prominent in Cases 1 and 2 while in Case 3, featured clinically by atrophic weakness, they were infrequent. In the latter the residual fibers were either large and dystrophic or small and atrophic. Electron microscopically, nearly all components of the muscle cell, in places, were involved in the dystrophic or atrophic process, such as myofilaments, Z discs, triads, nucleic, mitochondria, and the sarcolemma. In addition, cytoplasmic cysts, multilammellated bodies, and lipofuscin granules were observed. The most characteristic feature of the disease were sarcoplasmic masses, filled with varying amounts of disoriented myofilaments and other sarcoplasmic components. Disoriented myofibrils often encircled the remaining core of normal myofibrils, thus forming the striated annulets (Ringbinden). Several other abnormalities, not previously reported in myotonic dystrophy or any other myopathy, were identified in slightly dystrophic as well as in severaly atrophic fibers. These were large, homogenous lacunes derived from the sarcoplasmic reticulum and peculiar geometric arrangements of terminal cisternae. The origin of some other structures remains obscure. The relation of the dystrophic process to segmental degeneration and atrophy, the principal histologic findings in Steinert's disease, is unsettled since segmental necrosis was not observed in our samples for phase and electron microscopy.
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  • 3
    ISSN: 1432-1459
    Keywords: Ethylene oxide ; Peripheral neuropathy ; Morphometry ; Electron microscopy ; Demyelination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case is reported of ethylene oxide polyneuropathy after 5 months of exposure. There was symmetrical distal weakness of both lower extremities and transitory reduced nerve conduction velocities with increased latencies. Sural nerve biopsy revealed nerve fibre degeneration of the Wallerian type, associated with reduction of axonal cross-sectional areas and some degree of nerve fibre regeneration that could be confirmed morphometrically. In addition, there was conspicuous paranodal vesicular disintegration of individual myelin lamellae. Unusual cisternae with introverted hemidesmosomes were noted in endoneurial fibroblasts.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 128 (1972), S. 393-405 
    ISSN: 1432-0878
    Keywords: Peripheral nerve ; Polyamines ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Mit Hilfe der Autoradiographie von Semi- und Ultradünnschnitten wurde die Verteilung der Radioaktivität nach Applikation von 3H-Putrescin im intakten und im degenerierenden N. ischiadicus der Ratte sowie in Spinalganglien untersucht. Im intakten und im geschädigten Nerven war die Radioaktivität, die zum weit überwiegenden Anteil als Spermidin und Putrescin vorkam, in allen zellulären Bestandteilen des Nerven, im Cytoplasma, in den Kernen und sehr deutlich auch in den Markscheiden, lokalisiert. Im extrazellulären Raum und über den Kollagenfibrillen war demgegenüber nur eine sehr geringe Radioaktivität festzustellen. Die physiologische Funktion von Spermidin und Putrescin im Myelin und den anderen Zellbestandteilen wird in erster Linie im Zusammenhang mit der in diesen Strukturen ebenfalls lokalisierten RNA diskutiert, da zahlreiche Hinweise für eine Rolle der Polyamine in der RNA- und Proteinsynthese vorliegen.
    Notes: Summary The distribution of radioactivity from 3H-putrescine was studied in intact and degenerated sciatic nerves, and spinal ganglia of rats by means of high resolution autoradiography. During the first three days after the administration of the labeled putrescine, the main proportion of radioactive material in the nerves was represented by spermidine and putrescine. Both, in intact and degenerating nerves, developed silver grains were deposited in all cellular components of the nervous tissue, the myelin sheath being markedly tagged. Perineural tissue was also labeled considerably, however, there was no significant amount of label in the extracellular space and in the collagen fibrils. The possible physiological significance of putrescine and spermidine in myelin and in other cellular components of nerves is discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1607-1612 
    ISSN: 0887-6266
    Keywords: neutron scattering (SANS) from hot stretched polystyrene ; polystyrene, hot stretched, SANS study of ; chain deformation in hot stretched polystyrene, SANS study of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small-angle neutron scattering (SANS) has been used to investigate macromolecular orientation of uniaxially hot-stretched partially deuterated polystyrene. Principle radii of gyration and degree of eccentricity were measured over a range of hot-stretch temperatures, strain rates, and external draw ratios (EDR). Results show affine deformation for EDR 〈4 and an increase in the degree of local molecular orientation with increasing rate of strain and decreasing stretching temperature. It also is found that although the macromolecules follow the external stretching affinely on average, they do not deform uniformly.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 60 (1988), S. 152-153 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 539-548 
    ISSN: 0021-9304
    Keywords: cytokine delivery via covalent binding ; tissue repair ; biomaterials ; collagen ; transforming growth factor β ; polyethylene glycol ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To overcome rapid diffusion and clearance from the implant site and to increase stability, recombinant transforming growth factor β2 (TGF-β2) was covalently bound to injectable bovine dermal fibrillar collagen (FC) and its activity compared to admixed TGF-β2. Covalent binding was achieved in a two-step procedure: First, TGF-β2 was reacted with the difunctional polyethylene glycol (PEG) linker, and then the PEG-attached TGF-β2 (PEG-TGF-β2) was bound to the fibrillar collagen (FC-PEG-TGF-β2). Initial binding of TGF-β2 to difunctional succinimidyl glutarate (D-SG-PEG) or succinimidyl propionate polyethylene glycol (D-SE-PEG) linkers was completed after reacting for 8 or 10 min as monitored by reverse-phase high-performance liquid chromatography. After reaction with injectable fibrillar collagen, extraction of unbound PEG-TGF-β2 and Western blot analysis, using a TGF-β specific antibody, demonstrated that at least 85% of the TGF-β2 was bound to the fibrillar collagen. The activity of PEG-TGF-β2 was fully stable in phosphate-buffered saline at 4°C and 37°C for at least up to 4 weeks. Unmodified TGF-β2 mixed with fibrillar collagen was completely inactivated after 1 week of incubation, as measured by the mink lung epithelial cell (Mv1Lu) growth inhibition assay. Formulations of FC-PEG-TGF-β2 containing 40 μg/mL TGF-β2 were implanted subcutaneously into rats and analyzed after days 7, 21, and 42. All TGF-β2-containing formulations showed the TGF-β typical fibroblastic response at the day 7 time point. Covalent binding of TGF-β2 to collagen with both difunctional PEG crosslinkers resulted in a significantly stronger and longer-lasting TGF-β2 response than that observed with admixed formulations of collagen and TGF-β. The TGF-β response with FC-PEG-TGF-β2 lasted up to day 42 but was not seen after day 7 for TGF-β2 admixed to FC. These findings clearly demonstrate that TGF-β2 remains fully active after being covalently bound to collagen via difunctional PEG. In addition, covalent binding potentiates and prolongs in vivo TGF-β responses and stabilizes the TGF-β in vitro. Results suggest that this method of formulation could be useful to stabilize and deliver similar peptide growth factors or biologically active agents. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 539-548, 1998.
    Additional Material: 10 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 47 (1960), S. 417-433 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phosphorus trichloride and oxygen react readily with polyethylene to introduce phosphonic dichloride ( - POCl2) groups into the polymer (chlorophosphonation). Treatment of the resulting intermediate with water, alcohols, and amines yields polymeric alkylphosphonic acids, esters and amides, respectively. Derivatives containing as much as 16% phosphorus have been prepared. With increasing degree of phosphonation, polyethylene crystallinity is reduced, the acid and amide derivatives become stiffer, less extensible, and less soluble in nonpolar solvents, and internal plasticization is observed in the ester derivatives. No significant decrease in flammability is effected by phosphonation unless chlorine is introduced also. The ester and amide derivatives crosslink under mild conditions by an unknown mechanism, the acid derivative will crosslink on heating with litharge. The chlorophosphonation reaction is sensitive to inhibitors and no highly active catalyst was found. The rate appears to be governed by the rate at which oxygen dissolves in the mixture. Substitution of air or chlorine for oxygen, phenyldichlorophosphine or diphenylchlorophosphine for phosphorus trichloride results in introduction of phosphorus-containing groups into polyethylene, also, but at reduced rates. In sharp contrast to polyethylene's apparent stability toward the phosphonation conditions, polystyrene, poly(methyl methacrylate), and polyisobutylene undergo a rapid decrease in molecular weight on treatment with phosphorus trichloride and oxygen. The fact that these four polymers exhibit the same relative behavior, i.e., polyethylene is stable whereas the other three polymers are unstable, in various free radical processes argues for a free radical mechanism in the chlorophosphonation reaction.
    Additional Material: 8 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 46 (1960), S. 547-550 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 13 (1975), S. 215-219 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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