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  • 1
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 233 (1971), S. 197-199 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Adult New Zealand white rabbits of both sexes were infected by intraperitoneal inoculation of blood from mice infected with trypanosome parasites; five received Trypanosoma brucei brucei (Serial No. LUMP 143) which is maintained as a stabilate7, and seven received a T. brucei parasite (strain S 427 ...
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Ultrasructure Research 91 (1985), S. 104-111 
    ISSN: 0022-5320
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 48 (1979), S. 83-93 
    ISSN: 1432-0533
    Schlagwort(e): Incisures ; Light microscopy ; Teased nerve fibres ; Nerve crush ; Wallerian degeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary It is conventionally accepted that during the early stages of Wallerian degeneration of myelinated peripheral nerve fibres Schmidt-Lanterman incisures represent the sites at which the myelin sheath, together with enclosed axoplasm, is segmented into myelin ovoids. This mechanism is considered by some authors to be facilitated by the progressive intercalation of additional incisures in order to allow the later division of primary ovoids. We have demonstrated that this reported increase in the number of incisures is a misinterpretation of the changes occurring. By 36 h after crush of the rat sural nerve most myelinated fibres showed segmentation at incisures to form myelin ovoids. At 12 h and 24 h after crush, however, no ovoids were apparent and the number of incisures present was determined from teased fibres by light microscopy using oil immersion. There was no increase in the number of incisures either internodally or paranodally at 12 h and 24 h compared with a normal control population of fibres. However at 12 h, and to a greater extent at 24h, incisures were more readily apparent than in normal fibres. It is likely, therefore, that previous reports have confused an increase in the number of incisures with an increase in their perceptibility resulting from their progressive dilatation.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 52 (1980), S. 97-104 
    ISSN: 1432-0533
    Schlagwort(e): Schmidt-Lanterman incisures ; Sural nerve ; Remyelination ; Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A mechanism has been proposed previously for the formation of Schmidt-Lanterman incisures during ontogeny as myelinated nerve fibres increase in diameter. In this study, the mode of formation of incisures and their development were examined by light and electron microscopy in remyelinating fibres (16–200 d) of the sural nerve of rats following lysophosphatidyl choline (LPC)-induced segmental demyelination. In remyelination, a basic number of incisures is incorporated into the myelin sheath ab initio. Apparently these incisures which are at first circumferentially incomplete, being localised to the region of the mesaxons, progressively extend around the whole circumference of the myelin sheath. As fibre diameter increases, additional incisures are added, seemingly, by the intrusion of Schwann cell cytoplasm between the compact myelin lamellae, from the abaxonal side of the myelin sheath. The progressive differentiation of incisures is described in terms of their complement of organelles. The results are discussed with reference to the possible functions of incisures.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 54 (1981), S. 95-100 
    ISSN: 1432-0533
    Schlagwort(e): Ranvier node ; Wallerian degeneration ; Freeze fracture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Using the freeze-freeze-fracture technique, the sciatic nerve of the rat and rabbit was examined distally at 24 h after crush, with particular reference to the node of Ranvier and paranode. The paranodes, in the majority of myelinated fibres, showed a loss of the cytoplasmic circumferential bands and longitudinal columns and their associated membrane pores which characterise the normal Schwann cell surface. Axonal changes consisting of accumulations of axoplasmic organelles occurred at both the node and paranode. At the nodes large intramembraneous partiles in the axolemma (E face) appeared unchanged. Nodal Schwann cell microvilli and paranodal myelin terminal loops were generally unaffected. The findings are discussed in terms of the decrease in amplitude of the action potential which occurs in early Wallerian degeneration.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 180 (1989), S. 237-242 
    ISSN: 1432-0568
    Schlagwort(e): Perineurium ; Lanthanum ; Diffusion barriers ; In vivo ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary While the perineurium as a diffusion barrier has been extensively investigated by light and electron microscopy, copy, such studies have been largely restricted to the use of protein tracers. In the present study the permeability of the perineurium to a physiologically more relevant ionic tracer has been assessed. In vivo the rat sural or tibial nerve was either microinjected with lanthanum nitrate solution for endoneurial application or bathed in the lanthanum solution for epineurial application. The findings generally demonstrated an effective barrier to the tracer which failed to penetrate the inner layers of the perineurium. Only at the highest lanthanum concentration and longest time intervals employed did trace quantities occasionally penetrate the barrier and then only in the presence of some cytopathological changes to the outermost perineurial cells. The usefulness of the microinjection method was limited by the slight but unavoidable trauma to the perineurium. The findings are related to those of other studies which have used electron dense tracers, also to studies using physiological including electrophysiological techniques and morphological including freeze-fracture methods.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-0568
    Schlagwort(e): Key words γ-Glutamyl transpeptidase ; Alkaline phosphatase ; Blood-brain barrier ; Pial microvessels ; Astrocytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Pial microvessels have several important blood-brain barrier (BBB) characteristics in common with cerebral microvessels, despite lacking their astrocytic ensheathment. We have therefore determined whether they have the same distribution of two enzymes, γ-glutamyl transpeptidase (GGTP) and alkaline phosphatase, both of which are known to be astrocyte-dependent. GGTP was absent from all rat pial microvessels but strongly present in brain cortical capillaries. Alkaline phosphatase was heterogeneously expressed in pial microvessels, including capillaries, but strongly positive in brain cortical capillaries. Diffusible, inductive factors produced by astrocytes could account for these differences in enzyme distribution between the two vessel types. Furthermore, differences in expression between the two markers may reflect their differing sensitivities to the astrocytic factors. Caution is urged in the common usage of the pial microvessel as a model system in BBB studies.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 171 (1985), S. 339-344 
    ISSN: 1432-0568
    Schlagwort(e): Microtubules ; Myelinated axons ; Morphometry ; Computer analysis ; Literature review
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Employing current computer-aided morphometric techniques, axonal microtubule density was determined for the rat sural nerve. Analysis of extensive data showed that while microtubule number increases with axon size, the increase is not directly proportional. Thus the relationship between microtubule density and axonal size is inversely related, so that microtubule density is greater in smaller axons than in larger axons. When a proximal and distal site, separated by 2 cm, were compared for microtubule density there was no significant difference, using pooled data for all fibre diameters. The results are interpreted in terms of our present knowledge of axonal-microtubule quantitative relationships, which is reviewed.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-0533
    Schlagwort(e): Key words Dura ; Endothelium ; Headache ; Substance P ; Surface charge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Experimental data point to a determinant role for endothelial cell (EC) anionic sites in the regulation of vascular permeability. Previous studies have shown that EC anionic sites density is reduced in conditions of enhanced permeability. The pathophysiology of migraine and vascular headache encompasses dilatation of dural vessels and extravasation of plasma proteins. The current study was carried out to determine if the density of EC anionic sites is reduced in enhanced permeability of dural vessels. Enhanced permeability was chemically induced in rats by intravenous injection of substance P and was tested by assessing leakage of horseradish peroxidase (HRP). Anionic sites were labelled with cationic colloidal gold and their density was quantified from electron microscopy negatives. Experimental animals showed increased leakage of HRP from dural vessels. However, anionic sites in EC membranes (luminal and abluminal) showed no statistical differences when their mean densities in experimental and control animals were compared. The results indicate that in this model, factors other than the density of anionic sites may be important determinants in the permeability of dural vessels. Such factors may include structural alteration of ECs consistent with an increased permeability. In this study pronounced ultrastructural changes in ECs were noted in experimental animals including widening of intercellular junctions and an increase in the number of EC gaps and vesicles.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 199 (1999), S. 509-517 
    ISSN: 1432-0568
    Schlagwort(e): Key words Blood-brain barrier ; Blood-nerve barrier ; Endothelial cell ; Membrane markers ; Inductive mechanisms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  A number of major properties of endothelial cells (EC) at the blood-brain barrier (BBB) have been shown to be astrocyte-dependent. Whether analogous properties at the blood-nerve barrier (BNB) are induced and maintained by Schwann cells has not been investigated. As a preliminary investigation we have undertaken a comparative study of six EC membrane markers at the BBB and BNB and perineurium. Employing immunoblotting and immunocytochemistry the relative distribution between rat brain cortex and sciatic nerve was determined for the glucose transporter (GLUT-1), the transferin receptor (OX-26), the endothelial barrier antigen (EBA) and the OX-47 antigen. Using enzyme cytochemistry the same comparison was made for γ-glutamyl transpeptidase (GGTP) and alkaline phosphatase. By immunocytochemistry GLUT-1 was uniformly strongly represented in brain EC, nerve EC and perineurium. OX-26 was strongly positive in brain EC but present only in trace quantities in nerve EC and perineurium. EBA similarly showed strong positivity in brain EC and trace amounts in nerve EC but was absent from perineurium. OX-47 was present moderately in brain EC and perineurium but absent from nerve EC. Quantitative immunoblotting of brain and sciatic nerve homogenates showed statistically significant differences in the level of expression of EBA and OX-26 between the two tissues. Enzyme cytochemistry showed that GGTP was strongly positive in brain EC but absent from nerve EC and perineurium. Alkaline phosphatase stained strongly in brain and nerve EC and was absent from perineurium. In summary the six membrane markers were heterogeneously represented in nerve compared with brain. This pattern of distribution in the nerve cannot simply be accounted for by the absence of astrocytes and their inductive influences. Any inductive influences of Schwann cells require investigation.
    Materialart: Digitale Medien
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