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  • 1
    ISSN: 1432-0533
    Keywords: Key words B-50(GAP-43) ; Spinal cord ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract B-50(GAP-43) is a phosphoprotein mainly found in the nervous system which plays a major role in neurite growth during development and regeneration as well as in synaptic remodelling. In the mature intact central nervous system, intense B-50 immunoreactivity (B-50-IR) can still be detected in regions which maintain residual capacity for structural re-organization. B-50 expression has been studied extensively in laboratory animals; however, its distribution and regulation in the human spinal cord is largely unknown. As a first step to analyze lesion-induced structural alterations, we investigated the distribution of B-50 protein and mRNA in the normal adult human spinal cord and dorsal root ganglia. Intense B-50-IR was localized to the superficial laminae of the dorsal horn at all segmental levels, the intermediolateral nucleus at thoracic levels and Onuf’s nucleus at sacral levels. Scattered neurons, particularly in the ventral horn of lumbar and sacral segmental levels (and occasionally also in Clarke’s nucleus) displayed intense B-50-IR in close apposition to the perikaryal and proximal dendritic surfaces. Nonradioactive in situ hybridization indicated that B-50 mRNA could also be detected in neurons of the ventral horn and also in the intermediolateral nucleus. The distribution of B-50 mRNA and protein in the normal human spinal cord shows a marked similarity to that reported in experimental animals, including the selective labelling of Onuf’s nucleus. However, the strong B-50-IR on the surface of some large anterior horn motor neurons has not been observed in other mammals. This finding might reflect a particular state of readiness for synaptic plasticity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Thalidomide ; Wallerian degeneration ; Schwann cell proliferation ; Immune inhibition ; Endoneurial edema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In addition to the well-known teratogenic effect of thalidomide, previous studies have revealed mild immunosuppressive properties and, more recently, and antiangiogenic activity. To find out more about the specificity of these effects we studied the influence of orally administered thalidomide on Wallerian degeneration in rats. Wallerian degeneration is a potent experimental model for studying reproducible cell proliferation in vivo. Examination of distal nerve segments of transected sciatic nerves from rats that had been treated with thalidomide (2×250 mg/kg per day) revealed a significant reduction of endoneurial cell counts at 10–15 days after surgery compared to that seen in controls. This effect was not statistically significant, at a very early stage of Wallerian degeneration, i.e., at 5 days after transection of the nerve. Subperineurial edema and phagocytosis was also reduced, although this was not statistically significant. This apparently nonspecific inhibitory effect of thalidomide during early Wallerian degeneration shown in the present study should be investigated further for its possible relationship to other previously established inhibitory activities of thalidomide, especially its immunosuppressive effect in man.
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  • 3
    ISSN: 1432-0533
    Keywords: Unmyelinated axons ; Sensory neuropathy ; Thalidomide ; Aging ; Senile peripheral nerves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sural nerve biopsies of four patients, aged 54–76 years, with a predominantly sensory type of neuropathy following high dosages of thalidomide were examined by light and electron microscopy. The present study includes a qualitative and quantitative evaluation of unmyelinated nerve fibers. Despite severe neuropathy, increased numbers of small unmyelinated axons per endoncurial area were noted in all patients. This numerical increase appeared to be independent of aging, since it was not seen in two senile controls, studied at the age of 83 and 88 years. The increase in the endoneurial density of unmyelinated axons, especially of small sized fibers, is likely to be related to regeneration following degeneration of unmyelinated axons although endoneurial shrinkage secondary to loss of large myelinated fibers could have caused an additional increase in the number of axons per endoneurial area. Axonal sprouting, despite degeneration of large numbers of myelinated and unmyelinated fibers, appears to be consistent with some of the characteristic clinical features of thalidomide neuropathy such as paresthesias, hyperesthesia for pain and temperature, and disturbances of autonomic functions. On the other hand, a variable number of empty Schwann cells (bands of Büngner) and pockets at the surface of many Schwann cells noted in the four patients with neuropathy were also seen in both senile controls with no signs of neuropathy. Thus, it is obvious that pockets and empty Schwann cells may be related to aging or other causes of slow axonal wasting with Schwann cell proliferation and are not necessarily associated with clinically manifest neuropathy.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 65 (1985), S. 285-292 
    ISSN: 1432-0533
    Keywords: Thalidomide ; Neuropathy ; Conduction velocity ; Myelin sheath
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Morphological studies of experimental thalidomide neuropathy have thus far failed to show any significant structural changes. The present investigation was performed on sural nerves of female New Zealand white rabbits showing a reduction of sensory conduction velocity after oral treatment with thalidomide (100 mg/kg b.wt. per day) for a period of 33 weeks. Rabbits of the same strain and equal sex, weight, and number served as controls. Very few nerve fibers were undergoing Wallerian degeneration in both groups, experimental animals and controls. Morphometry, however, revealed a statistically significant reduction of the mean myelin thickness of sural nerve fibers in the thalidomide group of rabbits as compared to controls. The mean myelin thickness of the largest nerve fibers was also significantly smaller than in the control group. On the other hand, axonal diameters were not significantly altered. The association between the decrease of the sensory conduction velocity, the reduction of the myelin sheath thickness, and the chronic thalidomide application is discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 290 (1997), S. 31-37 
    ISSN: 1432-0878
    Keywords: Key words: Sural nerve ; Blood vessels ; Angiopathic neuropathy ; Vasculitis ; Peripheral neuropathy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The number and dimensions of epineurial blood vessels in normal human sural nerves have, thus far, not been determined using systematic, reproducible morphometric methods, although this nerve is most frequently used for diagnostic biopsies. Quantitative changes in epineurial blood vessels appear to be major parameters for identifying angiopathy and angiopathic peripheral neuropathy. Therefore, we examined the epineurial blood-vessel number in relation to the age of the patients and to the number and size of the nerve fascicles in each of 51 human sural nerve biopsies. The data from a control group were compared with pathological cases. We found that the number of epineurial blood vessels (normal mean: 57.7) increased significantly (up to 196) in biopsies where there were signs of angiopathy (P≤0.01) or vasculitis (P≤0.05). The increase in the number of epineurial blood vessels usually resulted from a proliferation of capillaries. The fascicular cross-sectional area did not appear to be related to the number of epineurial blood vessels, although it increased significantly in cases with vasculitis (P≤0.05) or an axonal type of neuropathy (P≤0.05). Thus, this study shows that the number of epineurial blood vessels is a helpful parameter in verifying angiopathy and angiopathic peripheral neuropathy.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 273 (1993), S. 499-509 
    ISSN: 1432-0878
    Keywords: Ranvier's node ; Development ; Sural nerve ; Axon ; Myelin sheath ; Paranodal junctions ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Developmental alterations of paranodal fiber segments have not been investigated systematically in human nerve fibers at the light- and electron-microscopic level. We have therefore analyzed developmental changes in the fine structure of the paranode in 43 human sural nerves during the axonal growth period up to 5 years of age, and during the subsequent myelin development up to 20 years and thereafter. The nodal, internodal, and paranodal axon diameters reach their adult values at 4–5 years of age. The ratio between internodal and paranodal axon diameters remains constant at 1.8–2.0. Despite a considerable increase in myelin sheath thickness, the length of the paranodal myelin sheath attachment zone at the axon does not increase correspondingly, because of attenuation, separation from the axolemma, and piling up of myelin loops in the paranode. Separation of variable numbers of terminal myelin loops from the underlying axolemma results in the formation of bracelets of Nageotte, whereas the transverse bands of these loops disappear. The adaptation of the paranodal myelin sheath to axonal expansion during development probably occurs by uneven gliding of the paranodal myelin loops simultaneously with internodal slippage of myelin lamellae. Since mechanically stabilizing structures (tight junctions and desmosomes between adjacent paranodal myelin processes; transverse bands between myelin loops and paranodal axolemma) are unevenly arranged, especially during rapid axonal growth, paranodal axonal growth with simultaneous adaptation of the myelin sheath is probably discontinuous with time.
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