Browsing by Subject "Peripheral nerve"

Now showing 1 - 5 of 5
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    A modified chemical protocol of decellularization of rat sciatic nerve and its recellularization with mesenchymal differentiated Schwann-Like cells: Morphological and functional assessments
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) García Pérez, M.M.; Martínez Rodríguez, H.G.; López Guerra, G.G.; Soto Domínguez, A.; Said Fernández, S.L.; Morales Ávalos, R.; Elizondo Omaña, R.E.; Montes de Oca Luna, R.; Guzmán López, S.; Castillo Galván, M.L.; Mendoza Lemus, O.F.; Vílchez Cavazos, F.
    The functional reconstruction of large neural defects usually requires the use of peripheral nerve autografts, though these have certain limitations. As a result, interest in new alternatives for autograft development has risen. The acellular peripheral nerve graft is an alternative for peripheral nerve injury repair, but to date there is not a standardized chemical decellularization method widely accepted. The objective of this study was to propose a modified chemical protocol of decellularization of rat sciatic nerve and its recellularization in vitro with mesenchymal differentiated Schwann-like cells. After the transplantation, an evaluation of its regeneration was performed using morphological and functional tests. The study consisted of two phases; in phase 1, different concentrations and times of exposure of rat sciatic nerves to detergents were tested, to establish a modified chemical protocol for nerve decellularization. The chemical treatment with 3% triton X-100 and 4% sodium deoxycholate for 15 days allowed a complete decellularization whilst conserving the extracellular matrix of the harvested nerve. In phase 2, the decellularized and recellularized alografts were compared against autografts. The morphological analysis showed a higher positivity to specific myelin antibodies in the recellularized group compared to the autograft. There were no differences in this parameter between the control limb and the experimental limb (recellularized group). The functional analysis showed no statistical differences at week 15 in the Sciatic Function Index in the autograft group vs the other groups. This study sets the morphological and functional bases for posterior studies about nerve defects regeneration in humans.
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    Effects of metabolic syndrome on the ultrastructure of the femoral nerve in aging rats
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) Rodrigues de Souza, Romeu; Gama, Eliane F.; El-Razi Neto, Semaan; Maldonado, Diogo
    The aim of the present study was to characterize the morphometry of the femoral nerve in aging rats with metabolic syndrome compared to controls. Systolic blood pressure and fasting plasma glucose were measured, and myelinated and unmyelinated fibers in the femoral nerves were quantitatively assessed under electron microscopy. Aging rats exposed to a regimen of metabolic syndrome developed elevation of plasma glucose concentration, mild hypertension and polyneuropathy characterized by a decrease in myelin fiber area, axon diameter, myelin sheath thickness and myelin fiber loss in the femoral nerve. The histogram of size distribution for myelinated fibers and axons from the aging rats of the control group was bimodal. For aging MS animals, the histogram turned out to be unimodal. The ultrastructure of unmyelinated fibers and of Schwann cells in 18-monthold rats was well preserved. Granules of lipofuscin were seen in unmyelinated fiber axons of 18-month-old rats with MS. The damage percentage of the large myelinated fibers has increased significantly in 18- month-old and 18-month-old (MS) rats in relation to the controls. No significant difference was observed among the groups for the g-ratio. Comparing the three groups, the number of neurotubules and neurofilaments in myelinated fibers of 18-month-old rats with MS was significantly smaller than for the groups of 18-month-old and 14-month-old rats. The overall changes seen in the femoral nerve from aging rats seem minor compared to the changes in the aging rats with MS, suggesting that long-term MS accelerates the progressive modifications in peripheral nerves that develop in old age.
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    Extent and duration of recovered pupillary light reflex following retinal ganglion cell axon regeneration through peripheral nerve grafts directed to the pretectum in adult rats
    (Elsevier, 1998-12) Whiteley, S. J. O.; Sauvé, Y.; Avilés Trigueros, Marcelino; Vidal Sanz, Manuel; Lund, R. D.; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    The functional reinnervation of the olivary pretectal nucleus (OPN) was studied in adult rats with peripheral nerve (PN) grafts bridging the interrupted retinopretectal pathway. Functional recovery was assessed quantitatively using established pupillometry techniques. The effect of intravitreal tuftsin fragment 1–3 (tuftsin 1–3) injections during the grafting procedure was also studied. A total of 53 adult rats received autologous PN grafts connecting the ocular stump of the transected optic nerve to the ipsilateral OPN. The contralateral eye was enucleated to remove the input from that eye to the OPN. A pupillary light reflex was elicited from 35 of the 53 PN-grafted animals and in the best cases, a response was obtained which compared closely to that recorded from control animals. Tuftsin 1–3 was found to increase the rate of recovery of the response. The response amplitude of PN-grafted rats was generally found to diminish with repeated stimulus presentation and also appeared to deteriorate with age. This was in contrast to control animals' responses. However, a PLR could still be elicited in 3 of the 6 animals studied 15 months after PN-grafting. These findings indicate that a near-normal PLR function can be restored using a peripheral nerve graft, but there are a number of factors that are likely to compromise optimal outcome.
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    Morphological abnormalities in the sural nerve from patients with peripheral vascular disease
    (Murcia : F. Hernández, 1991) Rodríguez-Sánchez, C.; Medina sánchez, M.; Malik, Rayaz A.; Ah-See, A.K.; Sharma, A.K.
    The present paper has been written in order to determine the morphological alterations in the sural nerve from patients with chronic arteriosclerotic occlusive disease. Eight patients with Peripheral Vascular Disease (PVD) and six age-matched control subjects were studied. Morphometric data revealed two groups of patients, one of them with mild disease (n=5), and the other one with severe damage (n=3,) consisting in loss of myelinated fibres and increase in the number of small fibres (p < 0.005). Teased nerve fibres and electron microscopic studies also showed two types of patients, with respect to the myelin or the axonal alterations. The unmyelinated fibre population was affected equally in both groups. In conclusion, this study supports the idea that ischemia is able to cause structural alterations in the peripheral nerve, and that it can play a role in the development of neuropathy.
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    Selective innervation of retinorecipient brainstem nuclei by retinal ganglion cell axons regenerating through peripheral nerve grafts in adult rats
    (Society for Neuroscience, 2000-01-01) Avilés Trigueros, Marcelino; Sauvé, Y; Lund, R D; Vidal-Sanz, M; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    The pattern of axonal regeneration, specificity of reinnervation, and terminal arborization in the brainstem by axotomized retinal ganglion cell axons was studied in rats with peripheral nerve grafts linking the retina with ipsilateral regions of the brainstem, including dorsal and lateral aspects of the diencephalon and lateral aspect of the superior colliculus. Four to 13 months later, regenerated retinal projections were traced using intraocular injection of cholera toxin B subunit. In approximately one-third of the animals, regenerated retinal axons extended into the brainstem for distances of up to 6 mm. Although axons followed different patterns of ingrowth depending on their site of entry to the brainstem, within the pretectum, they innervated preferentially the nucleus of the optic tract and the olivary pretectal nucleus in which they formed two types of terminal arbors. Within the superior colliculus, axons extended laterally and formed a different terminal arbor type within the stratum griseum superficiale. In the remaining two-thirds of the animals, retinal fibers formed a neuroma-like structure at the site of entry into the brainstem, or a few fibers extended for very short distances within the neighboring neuropil. These experiments suggest that regenerated retinal axons are capable of a highly selective reinnervation pattern within adult denervated retinorecipient nuclei in which they form well defined terminal arbors that may persist for long periods of time. In addition, these studies provide the anatomical correlate for our previous functional study on the re-establishment of the pupillary light reflex in this experimental paradigm.