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  • Polymer and Materials Science  (7)
  • Reinnervation  (3)
  • 1
    ISSN: 1432-2307
    Keywords: Muscle spindle ; Elastic fibres ; Elaunin fibres ; Oxytalan fibres ; Denervation ; Reinnervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle spindles in the lower lumbrical muscles of rats were studied by transmission electron microscopy following denervation with or without reinnervation. The number and total area of elastic fibres per muscle spindle increased at 3–12 months following various experimental procedures: (1) denervation and reinnervation after a single crush lesion to the sciatic nerve; (2) reinnervation after four-fold repeated crush injuries; and (3) transection and suture of the nerve. The increased number of oxytalan and elaunin fibres, the precursors of mature elastic fibres, within these muscle spindles provided further evidence for their numerical and dimensional increase. An attachment site of elastic fibres at the spindle pole was identified at the inner cells of the outer spindle capsule. The processes of these cells embraced terminating elastic fibres tightly. Attachment of elastic fibres to intrafusal muscle fibres was less conspicuous since they were not similarly embraced but were rather indistinctly, though closely, associated with the basal lamina along longitudinal surface indentations of intrafusal muscle fibres. It is concluded from this series of experiments that muscle spindles, as dynamic mechanoreceptors, maintain their elastic properties even under pathological conditions. The increase of elastic fibres following denervation and reinnervation represents an obviously meaningful reaction that may compensate for loss of tonic properties of muscle spindles without causing stiffness.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 80 (1990), S. 163-171 
    ISSN: 1432-0533
    Keywords: Neuromuscular spindle ; Reinnervation ; Nerve endings ; Autonomic innervation ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle spindles from the lower lumbrical muscles of rats were studied by transmission and scanning electron microscopy following reinnervation (i) after a single sciatic nerve crush lesion and (ii) after transection and immediate epineurial suture of the sciatic nerve. In all muscle spindles, regenerated sensory or motor nerve endings were encountered 3 months after making the lesions although in the nerve-transection group, regenerated nerve endings were seen less frequently before 6 months of recovery. Abnormalities in reinnervated spindles following neurotomy comprised: (1) multiplicity of axonal sprouts (hyperinnervation), sometimes irregularly related to, although never in direct contact with, regenerated sensory nerve endings; (2) altered contact relationships between sensory nerve endings and intrafusal muscle fibers; (3) abnormal structure of nerve endings; and (4) irregular association of Schwann cell processes to regenerated sensory nerve endings. These findings indicate that reinnervation of muscle spindles following transection and suture of a peripheral nerve, i.e., after complete interruption of its continuity, in fact, occurs although the fine structural abnormalities observed are supposed to interfere with adequate functional restoration.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Muscle spindle ; Denervation ; Reinnervation ; Muscle fiber atrophy ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of normal, denervated, and reinnervated muscle spindles in lower lumbrical muscles of rats was studied morphometrically at time intervals ranging from 3–14 months. In control spindles, the mean transverse area of mitochondria was estimated to be more than twice as large in nuclear chain than in typical nuclear bag fibers. Following denervation, there was a severe decrease of the mean number and transverse area of mitochondria, and a moderate, but statistically significant decrease of the mean transverse area of intrafusal muscle fibers (IMFs) despite an increase of the number of IMFs. At 12–14 months of reinnervation, changes of the transverse areas of IMFs were statistically insignificant, but the mean values for the mitochondria were incompletely restored. At 4×3 months, after fourfold repeated crush injuries to the nerve, most of the values estimated (transverse area of mitochondria; number, shape, and transverse area of IMFs and nuclei) tended to approach those in denervated rather than in reinnervated IMFs. The differences of the reactions of intra- and extrafusal muscle fibers following complete motor and sensory denervation appeared to be in accordance with their normal dimensional dissimilarities.
    Type of Medium: Electronic Resource
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  • 4
    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.
    Type of Medium: Electronic Resource
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  • 5
    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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  • 6
    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.
    Type of Medium: Electronic Resource
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  • 7
    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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  • 8
    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.
    Type of Medium: Electronic Resource
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 2189-2195 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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