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  • Polymer and Materials Science  (5)
  • Denervation atrophy  (3)
  • 1
    ISSN: 1432-0533
    Keywords: Skeletal muscle ; Denervation atrophy ; Target fibres ; Analysis of size distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An analysis of frequency distribution is performed in 250 target and targetoid fibres each from the anterior tibial muscle of a case with rapidly proceeding denervation atrophy. Following plane measurements on cross sections the size data were analysed according to the method of Daeves and Beckel [1] for mixed distributions. Three homogeneous normally distributed populations could thus be extracted from the mixed distributed sample. The largest population represents target fibres with a normal size range, while the second one encloses hypertrophic fibres, and the third and smallest one consists of fibres ranging within atrophic size limits. These findings support the previous presumption that targets predominantly occur in fibres of normal size and can therefore be regarded as manifestations of an early stage of denervation atrophy. The targetoid fibres, on the contrary, are of an atrophic size by 84%, while only a small population of about 15% contains targetoid fibres of a normal size on cross section.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 210 (1975), S. 167-181 
    ISSN: 1432-1459
    Keywords: Denervation atrophy ; Target and targetoid/core fibers ; Pathogenetic relation ; Voluntary muscle ; Muscle pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im M. tibialis anterior eines 68 Jahre alt gewordenen Mannes, der 1/2 Jahr vor seinem Tode am Herzinfarkt eine rasch progrediente neurogene Muskelatrophie in den Beinen entwickelte, fanden sich außerordentlich zahlreiche unifokal-konzentrische Muskelfaserveränderungen wie Target-, Targetoid/Core- und Targetoidfasern. Außerdem sah man große vacuolisierte Faserquerschnitte mit multiplen fokalen Veränderungen in der Randzone, die an die früher beschriebenen „cytoplasmic bodies“ erinnerten; im vorliegenden Zusammenhang wurden sie allerdings als Fasern mit multizentrischen Target- und Targetoidformationen interpretiert. Die Targetfasern zeigten eine weitläufige Variation in der äußeren Erscheinungsform, die in der Zusammenschau kontinuierliche Übergänge zu Targetoid/Corefasern (mit dichter Zentralzone) und Targetoidfasern (mit zentraler Auflösung und Vermehrung aquösen Sarkoplasmas mit wenigen fibrillären Strukturen) erkennen ließ. Wenige Fasern mit einer zentralen Verdichtung fibrillären Materials mit oder ohne schmaler Intermediärzone waren Corefasern des Central-Core-Disease auffallend ähnlich; andere glichen mehr dem Typ von Targetoidfasern mit strukturdichtem Zentrum, wie sie in der früheren Literatur beschrieben wurden. Beide Formen wurden wegen ihrer großen Ähnlichkeit von Engel et al. (1966) unter dem Begriff „Targetoid/Core Fibers“ zusammengefaßt. Das gleichzeitige Auftreten der verschiedenen Formen konzentrischer Faserveränderungen in einem Muskel legt die Annahme nahe, daß zwischen allen eine enge Beziehung im Sinne unterschiedlicher Manifestationsstufen des grundsätzlich gleichen pathogenetischen Prozesses besteht. So wäre unter dieser Annahme beispielsweise das Central-Core-Disease eine Erkrankung mit einer Generalisation konzentrischer Faserveränderungen, die im frühesten morphologischen Entwicklungsstadium zum Stillstand gekommen sind.
    Notes: Summary In the m. tibialis anterior of a 68-year-old man with rapidly developing denervation atrophy in the legs since 1/2 year prior to death from heart stroke, abundant unifocal concentric fiber changes, such as target, targetoid/core, and targetoid fibers could be observed. Besides, large vacuolized fibers with multiple changes resembling cytoplasmic bodies in the peripheral zone were present as well; they are interpreted as fibers with multicentric target or targetoid formations. The target fibers displayed a broad variation of their outer appearance suggesting a continuous transition to targetoid/core fibers (with a dense center) and targetoid fibers (with a central change to aquous sarcoplasm showing a paucity of fibrillar structures). Very few fibers with a central densification of fibrillar material with or without a thin intermediate zone were fairly akin to core fibers of central core disease; others were more alike the type of targetoid fibers, previously described in the literature, showing a dense target-like center; both were summarized under the term, inaugurated by Engel et al. (1966), “targetoid/core fibers”. Simultaneous occurence of the different kinds of concentric fiber changes suggested a strong relation between all of them in the sense of representing different developmental stages of the same pathogenetic process. Thus, the central core disease, for instance, might be a disorder with a generalization of concentric fiber changes having come to arrest in the earliest stage of development.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 214 (1977), S. 159-162 
    ISSN: 1432-1459
    Keywords: Voluntary muscle ; Denervation atrophy ; Myopathy ; Target fibers ; Fiber splitting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Faserspaltungsphänomene an Targetfasern in einem Fall von neurogener Muskelatrophie der Beine mit ausgeprägter Begleitmyopathie werden beschrieben und diskutiert. Erstmals wird das typisch myopathische Phänomen der Faserspaltung an für die neurogene Muskelatrophie als typisch erachteten Targetfasern dargestellt.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 961-978 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The x-ray structure of Boc-L-Ala-Aib-Ala-Aib-Ala-Glu(OBzl)-Ala-Aib-Ala-Aib-Ala-OMe(I) represents the first α-helix determined by direct methods. This undecapeptide is a model of the N-terminus of alamethicin, and it exhibits voltage-dependent pores in bilayer membranes at a higher voltage and concentration than alamethicin. The molecule crystallizes in the monoclinic space group P21 with a = 10.602(1), b = 23.884(3), c = 13.622(1) Å, β = 95.61(6)°, and Z = 2. It adopts a right-handed α-helical conformation in the solid state with intramolecular 5 → 1 hydrogen bonds. An additional intramolecular hydrogen bond is bifurcated, forming a stronger 4 → 1 interaction (i.e., a β-turn III) and a weaker 5 → 1 interaction, thus prolonging the α-helical part up to 9 residues. The α-helix radius of 2.1 Å, the height per residue (distance Ni … Ni + 4) of 1.53 Å, the resulting length of the α-helical part of 13.8 Å (9 residues) resp. 15.3 Å (10 residues), the van der Waals radius (4.7 Å), and the minimal diameter of pores formed by aggregation of 3-10 α-helices were calculated omitting the Glu(OBzl) side chain. In the crystal, the α-helices are linked head to tail via two hydrogen bridges forming continuous chains. Adjacent helices are oriented in antiparallel with their helix axes and have only van der Waals contacts.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boc-L-Leu-Aib-Pro-Val-Aib-Aib-Glu(OBzl)-Gln-Phl (Boc = t-butyloxycarbonyl, Aib = α-aminoisobutyric acid, Bzl = benzyl, Phl = phenylalaninol), C59H90N10O14, the protected C-terminal nonapeptide with the sequence 12-20 of alamethicin, crystallizes in the orthorhombic space group P212121 with a = 15.666, b = 16.192, c = 26.876 Å, and Z = 4. The molecular conformation is right-handed helical with three α-(5 → 1 hydrogen bonds) and three β-turns (4 → 1 hydrogen bonds). All but two of the hydrogen bonds are significantly longer than the usual value and show bifurcation to some extent. The α/310r-helical nonapeptide molecules are arranged head-to-tail along the a direction. The resulting linear antiparallel chains are linked by a weak intermolecular hydrogen bridge, thus forming a two-dimensional layer structure in the ab plane. The conformation of this nonapeptide is almost identical with that of the corresponding C-terminal part found by x-ray crystallography of the eicosapeptide alamethicin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 241-246 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-, 1H-nmr, CD, and x-ray crystallography revealed β-turns of type III for Boc-Gly-L-Ala-Aib-OMe, Boc-L-Ala-Aib-L-Ala-OMe; the 310-helix for Boc-Aib-L-Ala-Aib-L-Ala-Aib-OMe; and antiparallel arranged α-helices for Boc-L-Ala-Aib-Ala-Aib-Ala-Glu(OBzl)-Ala-Aib-Ala-Aib-Ala-OMe. An N-terminal rigid α-helical segment is found in the polypeptide antibiotics alamethicin, suzukacillin, and trichotoxin. The α-helix dipole is essential for their voltage-dependent pore formation in lipid bilayer membranes, which is explained by a flip-flop gating mechanism based on dipole-dipole interactions of parallel and antiparallel arranged α-helices within oligomeric structures.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 9 (1984), S. 193-200 
    ISSN: 0721-3115
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of modified forms of the Rosenthal electrothermal equation to aid in the design of a capacitor discharge firing circuit for a specific detonator is described. The electrothermal parameters Cp and γ, representing the heat capacity of the bridge and the heat loss factor, respectively, were calculated from previously obtained firing data for the detonator. These calculations provided input to the design of a firing circuit utilizing electrolytic capacitors, which have a large value of electrical capacity but also a non-negligible internal resistance. Calculations were performed which (1) revealed the degrading effect on detonator initiation caused by too large a value of internal resistance, and (2) permitted selection of a particular capacitor that would allow reliable functioning of the detonator with initiation times of about 230 μs. The circuit was designed utilizing this capacitor, and in the experimental evaluation of the circuit the measured initiation times were compared with the calculated values. Good agreement between the two was documented, and the conclusion was reached that the detonator functioned reliably. The merits of the electrothermal analysis and the assumptions utilized therein relative to a vigorous heat transfer/reaction kinetics modeling of the flow of energy from the bridge into the explosive flash charge are discussed in detail.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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