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  • 1
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Morphometry ; Diabetes mellitus ; Hypomyelination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relative changes in the growth and maturation of axon size and myelin thickness were studied in the medial plantar division of the tibial nerve in the lower leg and in the motor branches of the tibial nerve to the calf muscles in rats in which diabetes mellitus had been induced with streptozotocin at the time of weaning. Observations were made at 6 weeks and 3, 6, 9 and 12 months of diabetes for comparison with age-matched controls. Similar changes were observed in both nerves. Growth in body weight and skeletal growth was severely retarded from the time of induction of diabetes but at the 6-week stage axon size was not reduced, suggesting that neural growth may initially be relatively protected. At later stages axon size was consistently reduced in the diabetic animals as compared with the controls and showed an absolute reduction at 12 months, as compared with 9 months, that was greater than in the controls. Myelin thickness became reduced earlier and was more severely affected than axon size so that the fibers were relatively hypomyelinated. The myelin changes were greater in larger than in smaller fibers. The index of circularity of axons was reduced in the diabetic nerves. These results show that induction of diabetes in prepubertal rats produces effects on peripheral nerve fibers which differ from those resulting from diabetes induced in adult animals. The effects also differ between large and small nerve fibres. These observations may explain some of the disparate findings obstained in previous studies on experimental diabetes in rats.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 62 (1984), S. 316-323 
    ISSN: 1432-0533
    Keywords: Experimental allergic neuritis ; Macrophage function ; Silica blockade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The selective toxicity of silica dust for macrophages has been used to assess the role of these cells in experimental allergic neuritis (EAN). Inbred Lewis rats were inoculated with bovine dorsal roots in Freund's complete adjuvant (day 0). In two experiments, animals received 200 mg of silica dust in 1 cm3 of saline intraperitoneally (IP) at days 8 and 16. In another two experiments, animals received IP silica at days 3, 7, and 11. Control animals received 1 cm3 saline IP at corresponding times. Regular clinical assessment showed that in animals treated on days 8 and 16 there was a significant delay in the time taken to reach their maximum degree of illness. This delay was not seen in the animals treated on days 3, 7, and 11. Neither of the injection regimes reduced the final maximum severity of the disease. In three experiments recovery of the treated and control animals occurred concurrently, hence the duration of the disease was reduced in the animals treated at days 8 and 16. However, in one group of animals given silica at days 3, 7 and 11, there was a delay in the time taken to recover from the most severe phase of the disease but thereafter the treated animals improved more quickly to reach their best grade at the same time as the controls. If the silica blockade of macrophages is to be effective in delaying the onset of EAN, the timing of injections is critical.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 59 (1983), S. 262-268 
    ISSN: 1432-0533
    Keywords: Experimental allergic neuritis ; Cyclosporin-A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experimental allergic neuritis (EAN) was induced in guinea pigs and rats and treated with Cyclosporin-A (Cy-A). When Cy-A was given prophylactically for 1 month from the time of induction of the disease, it prevented the development of EAN during the course of its administration. When Cy-A was given therapeutically after the onset of neurological signs, it effectively prevented further deterioration. This effect was more marked after 3 weeks' treatment than after only 1 week's treatment. In both regimens, when dosing with Cy-A ceased there was a latent period before clinical signs of EAN developed. This latent period is similar to that seen in the development of EAN in normal control animals and is probably due to the continued presence of antigen at the injection sites. After primary treatment of EAN with Cy-A, animals that relapsed did not respond to further treatment with Cy-A. Histological examination revealed that the nature of the EAN lesions in both groups of animals given Cy-A were not as severe as those seen in control animals. Despite these observations, there was no statistically significant difference between the maximum clinical grades reached by animals in any one group. These experiments suggest that T-cells are important in the development of EAN and that Cy-A interferes with this process by suppressing T-helper cells. They also show that it is possible to influence favourably the course of immune mediated neurological disease.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Human diabetic polyneuropathy ; Perineurium ; Tight junctions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Perineurial cells in the human sural nerve possess tight junctions which in freeze-fracture replicas are seen to be composed of networks of branching and anastomosing P face strands and E face grooves. Isolated circular tight junctions (maculae occludentes) may represent attachment devices between adjacent perineurial lamellae. At the overlapping margins of the cells, a beltlike tight junction (zonula occludens) encircles the cells and is believed to comprise a paracellular diffusion barrier. As the permeability of the perineurium has been found to be altered in diabetic polyneuropathy, the zonulae occludentes have been studied. In freeze-fracture replicas from cases of diabetic polyneuropathy a mixed population of structurally normal and abnormal junctions was observed. In some, the strands were abnormally curved with reduced numbers of intersections, the intervening plasma membrane displaying prominent P face concavities and E face convexities. At other sites, the junctions were severely disorganized and represented by fragmented and isolated strands with few intersections and numerous free ends. These abnormalities resemble changes that have been produced experimentally in epithelial tight junctions by osmotic damage. The possibility is considered that similar mechanisms could result in the alterations of the perineurial tight junctions in diabetic polyneuropathy and account for its impaired permeability barrier properties.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0533
    Keywords: Experimental allergic neuritis ; Suppression ; Bovine dorsal root ; Lewis rat ; Resistance to reinduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The injection of bovine dorsal root antigen in complete Freund's adjuvant can be used to produce experimental allergic neuritis (EAN) in rats. In this study attempts were made to prevent the development of the disease by prior injections of antigen. It was found that eight intradermal (i.d.) injections of antigen in either incomplete Freund's adjuvant or in saline failed to suppress EAN. A single intraperitoneal (i.p.) injection of antigen in saline produced only minimal protection against the disease. However, it was found that rats which had been given a primary course of EAN were subsequently completely unresponsive to a second injection of antigen.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Experimental diabetes ; Intramembranous particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Freeze-fracture studies have been made on the sciatic nerve of rats with chronic streptozotocin-induced diabetes mellitus. The density of intramembranous particles was reduced in both the P and E faces of the axolemma of myelinated and unmyelinated axons, in myelin and in the perineurial cells. This may reflect a general reduction in protein synthesis, or excessive protein degradation, related to the diabetic state. The perineurial cells also showed gap junctions which are not normally present in adult rat peripheral nerve. These may represent a reaction to changes in perineurial activity consequent to alterations in the endoneurial tissue fluid.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0533
    Keywords: Metachromatic leukodystrophy ; Peripheral nerve ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural findings in nerve biopsies from two cases of late onset metachromatic leukodystrophy were compared with those in cases of late infantile and juvenile onset. Hypertrophic changes and regenerating clusters were more evident in the late onset cases, in which macrophages were less frequent, presumably reflecting the chronicity of the disorder in this form. Inclusions within Schwann cells and endoneurial macrophages were similar in all four cases. Myelin figures, in which the periodicity of major dense lines was 8 nm, were present in Schwann cells associated with myelinated axons. The electron lucent zones between the major dense lines were bisected by lines of lesser electron density. These inclusions were probably related to myelin breakdown. All other inclusions displayed a periodicity of 5.8 nm and consisted of zebra bodies, vacuoles containing irregularly orientated lamellar material and stacks of flattened discs. These inclusions represented the metachromatic sulphatide deposits. Occasional inclusion bodies were observed within axons.
    Type of Medium: Electronic Resource
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