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Can Wistar rats be used as the normotensive controls for nerve morphometry investigations in spontaneously hypertensive rats (SHR)?; Ratos Wistar podem ser utilizados como os controles normotensos dos ratos espontaneamente hipertensos (SHR) em investigações morfométricas de nervos periféricos?

SANADA, Luciana Sayuri; TAVARES, Marcelo Rodrigo; NEUBERN, Milena Cardoso Maia; SALGADO, Helio Cesar; FAZAN, Valéria Paula Sassoli
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
38.242134%
PURPOSE: We compared the sural nerve morphology among Wistar (WR), Wistar-Kyoto (WKY) and Spontaneously hypertensive (SHR) rats, including the nerve fascicles and myelinated fibers morphometry. METHODS: Age matched (20 weeks) female WR (N=6), WKY (N=6) and SHR (N=7) had their right and left sural nerves removed, embedded in epoxy resin, and observed by light microscopy. Morphometric analysis was performed with the aid of computer software. RESULTS: Despite presenting the same age, WR were heavier than WKY and SHR, as were SHR compared to WKY. Systolic arterial pressure was higher in SHR compared to WR, but no differences between SHR and WKY or WR and WKY were observed. The sural nerves were morphometrically symmetric between proximal and distal segments on the same side and between sides in all strains with no differences in the myelinated fiber number. Schwann cell number and density were smaller in SHR and G ratio was larger in SHR, indicating that SHR have thinner myelinated fibers. CONCLUSION: Sural nerve morphology is similar between WKY and WR, allowing the use of WR as the SHR controls in morphological investigations involving peripheral neuropathies.; OBJETIVO: Comparar a morfologia do nervo sural em ratos Wistar (WR), Wistar Kyoto (WKY) e espontanemanete hipertensos (SHR)...

Phrenic nerve diabetic neuropathy in rats: unmyelinated fibers morphometry

FAZAN, Valeria Paula S.; RODRIGUES FILHO, Omar A.; JORDAO, Caroline E. R.; MOORE, Kenneth C.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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We have demonstrated that phrenic nerves` large myelinated fibers in streptozotocin (STZ)-induced diabetic rats show axonal atrophy, which is reversed by insulin treatment. However, studies on structural abnormalities of the small myelinated and the unmyelinated fibers in the STZ-model of neuropathy are limited. Also, structural changes in the endoneural vasculature are not clearly described in this model and require detailed study. We have undertaken morphometric studies of the phrenic nerve in insulin-treated and untreated STZ-diabetic rats and non-diabetic control animals over a 12-week period. The presence of neuropathy was assessed by means of transmission electron microscopy, and morphometry of the unmyelinated fibers was performed. The most striking finding was the morphological evidence of small myelinated fiber neuropathy due to the STZ injection, which was not protected or reversed by conventional insulin treatment. This neuropathy was clearly associated with severe damage of the endoneural vessels present on both STZ groups, besides the insulin treatment. The STZ-diabetes model is widely used to investigate experimental diabetic neuropathies, but few studies have performed a detailed assessment of either unmyelinated fibers or capillary morphology in this animal model. The present study adds useful information for further investigations on the ultrastructural basis of nerve function in diabetes.; FAPESP[07/08498-7]; FAPESP[04/09139-2]; FAPESP[04-01390-8]; FAPESP[06/03200-7]; FAPESP[06/06362-8]; CNPq[303802/2006-5]; CNPq[202079/2007-4]

A morphometric study on the longitudinal and lateral symmetry of the sural nerve in mature and aging female rats

JERONIMO, Andre; JERONIMO, Claudia Alem Dominques; RODRIGUES FILHO, Omar Andrade; SANADA, Luciana Sayuri; FAZAN, Valeria Paula Sassoli
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
38.488252%
Aging affects peripheral nerve function and regeneration in experimental models but few literature reports deal with animals aged more than one year. We investigated morphological and morphometric aspects of the sural nerve in aging rats. Female Wistar rats 360, 640 and 720 days old were killed, proximal and distal segments of the right and left sural nerves were prepared for light microscopy and computerized morphometry. No morphometric differences between proximal and distal segments or between right and left sides at the same levels were found in all experimental groups. No increase in fiber and axon sizes was observed from 360 to 720 days. Likewise, no difference in total myelinated fiber number was observed between groups. Myelinated fiber population distribution was bimodal, being the 720-days old animals` distribution shifted to the left, indicating a reduction of the fiber diameters. The 9 ratio distribution of the 720-days old animals` myelinated fiber was also shifted to the left, which suggests axonal atrophy. Morphological alterations due to aging were observed, mainly related to the myelin sheath, which suggests demyelination. Large fibers were more affected than the smaller ones. Axon abnormalities were not as common or as obvious as the myelin changes and Wallerian degeneration was rarely found. These alterations were observed in all experimental groups but were much less pronounced in rats 360 days old and their severity increased with aging. in conclusion...

Methods for exploring the morpho-functional relations of the aortic depressor nerve in experimental diabetes

CARMO, Jussara Marcia do; FAZAN JUNIOR, Rubens; SALGADO, Helio Cesar; FAZAN, Valeria Paula Sassoli
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.48825%
The present study investigated morpho-functional relations of the aortic depressor nerve (ADN) 5, 15 and 120 days after the onset of streptozotocin-induced diabetes in rats. Time control animals received vehicle. Under pentobarbital anesthesia, ADN activity was recorded simultaneously with arterial pressure. After the recordings, nerves were prepared for light microscopy study and morphometry. ADN function was accessed by means of pressure-nerve activity curve (fitted by sigmoidal regression) and cross-spectral analysis between mean arterial pressure (MAP) and ADN activity. The relation between morphological (myelinated fibers number and density, total myelin area, total fiber area and percentage of occupancy) and functional (gain, signal/noise relation, frequency) parameters were accessed by linear regression analysis and correlation coefficient calculations. Functional parameters obtained by means of the sigmoidal regression curve as well as by cross-spectral analysis were similar in diabetic and control rats. Morphometric parameters of the ADN were similar between groups 5 days after the onset of diabetes. Average myelin area and myelinated fiber area were significantly smaller on diabetic rats 15 and 120 days after the onset of diabetes...

Dorsal cutaneous branch of the ulnar nerve: a light and electron microscopy histometric study

OLIVEIRA, Adriana L. C. R. D.; FAZAN, Valeria P. S.; MARQUES JR., Wilson; BARREIRA, Amilton A.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
38.679019%
This study describes the normal morphology and morphometry of the dorsal cutaneous branch of the ulnar nerve (DCBU) in humans. Fourteen nerves of eight donors were prepared by conventional techniques for paraffin and epoxy resin embedding. Semiautomatic morphometric analysis was performed by means of specific computer software. Histograms of the myelinated and unmyelinated fiber population and the G-ratio distribution of fibers were plotted. Myelinated fiber density per nerve varied from 5,910 to 10,166 fibers/mm(2), with an average of 8,170 +/- 393 fibers/mm(2). The distribution was bimodal with peaks at 4.0 and 9.5 mu m. Unmyelinated fiber density per nerve varied from 50,985 to 127,108, with an average of 78,474 +/- 6, 610 fibers/mm(2), with a unimodal distribution displaying a peak at 0.8 mu m. This study thus adds information about the fascicles and myelinated and unmyelinated fibers of DCBU nerves in normal people, which may be useful in further studies concerning ulnar nerve neuropathies, mainly leprosy neuropathy.; CNPq Conselho Nacional de Desenvolvimento Cientifico e Tecnologico[305214/2009-8]; FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[06/03200-7]; FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[06/06362-8]; Fundacao de Apoio ao Ensino e Pesquisa (FAEPA) do Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto

Sural nerve involvement in experimental hypertension: morphology and morphometry in male and female normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR)

Sanada, Luciana Sayuri; Kalil, Andrea Lurdes da Rocha; Tavares, Marcelo Rodrigo; Neubern, Milena Cardoso Maia; Salgado, Helio Cesar; Fazan, Valeria Paula Sassoli
Fonte: BIOMED CENTRAL LTD; LONDON Publicador: BIOMED CENTRAL LTD; LONDON
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.91722%
Background: The sural nerve has been widely investigated in experimental models of neuropathies but information about its involvement in hypertension was not yet explored. The aim of the present study was to compare the morphological and morphometric aspects of different segments of the sural nerve in male and female spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Rats aged 20 weeks (N = 6 in each group) were investigated. After arterial pressure and heart rate recordings in anesthetized animals, right and left sural nerves were removed and prepared for epoxy resin embedding and light microscopy. Morphometric analysis was performed with the aid of computer software, and took into consideration the fascicle area and diameter, as well as myelinated fiber number, density, area and diameter. Results: Significant differences were observed for the myelinated fiber number and density, comparing different genders of WKY and SHR. Also, significant differences for the morphological (thickening of the endoneural blood vessel walls and lumen reduction) and morphometric (myelinated fibers diameter and G ratio) parameters of myelinated fibers were identified. Morphological exam of the myelinated fibers suggested the presence of a neuropathy due to hypertension in both SHR genders. Conclusions: These results indicate that hypertension altered important morphometric parameters related to nerve conduction of sural nerve in hypertensive animals. Moreover the comparison between males and females of WKY and SHR allows the conclusion that the morphological and morphometric parameters of sural nerve are not gender related. The morphometric approach confirmed the presence of neuropathy...

Aspectos descritivos e quantitativos da anatomia macroscópica e microscópica do nervo vestíbulo-coclear de cobaias; Descriptive and Quantitative Aspects of macroscopic and microscopic anatomy of the vestibulocochlear nerve of guinea pigs

Vasconcelos, Carlos Augusto Carvalho de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/06/2005 PT
Relevância na Pesquisa
48.913394%
O nervo vestíbulo-coclear da cobaia possui peculiaridades não encontradas em outros nervos periféricos. Não foram encontradas informações detalhadas sobre os aspectos morfométricos do VIII nervo craniano em cobaias adultas na literatura. A avaliação descritiva e quantitativa no presente estudo, evidencia informações que precedem o estudo das alterações que ocorrem em modelos experimentais de neuropatias do VIII nervo craniano e as doenças ou lesões que possam afetar o homem. Foram utilizadas 8 cobaias adultas, perfundidas com glutaraldeído a 2,5% em tampão cacodilato de sódio (0,025 M). Seus nervos direito e esquerdo (n=6, 4 nervos direito e 2 esquerdos) foram dissecados na região mediana do nervo e pós fixado com tetróxido de ósmio (OsO4) a 1% e incluídos em resina epóxi Poly/Bed 812®. Os fragmentos foram cortados em secções transversais semifinas seriadas (6 nervos) com uma espessura de 0,5 μm e corados com azul de toluidina para a microscopia de luz. Foram analisados os aspectos histológicos descritivos e topográficos do nervo vestíbulo-coclear em cobaias adultas, bem como os aspectos histométricos na parte mediana do nervo, no referente a densidade de fibras mielínicas, a distribuição dos diâmetros de tal tipo de fibras mielínicas...

Can Wistar rats be used as the normotensive controls for nerve morphometry investigations in spontaneously hypertensive rats (SHR)?

Sanada,Luciana Sayuri; Tavares,Marcelo Rodrigo; Neubern,Milena Cardoso Maia; Salgado,Helio Cesar; Fazan,Valéria Paula Sassoli
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
38.242134%
PURPOSE: We compared the sural nerve morphology among Wistar (WR), Wistar-Kyoto (WKY) and Spontaneously hypertensive (SHR) rats, including the nerve fascicles and myelinated fibers morphometry. METHODS: Age matched (20 weeks) female WR (N=6), WKY (N=6) and SHR (N=7) had their right and left sural nerves removed, embedded in epoxy resin, and observed by light microscopy. Morphometric analysis was performed with the aid of computer software. RESULTS: Despite presenting the same age, WR were heavier than WKY and SHR, as were SHR compared to WKY. Systolic arterial pressure was higher in SHR compared to WR, but no differences between SHR and WKY or WR and WKY were observed. The sural nerves were morphometrically symmetric between proximal and distal segments on the same side and between sides in all strains with no differences in the myelinated fiber number. Schwann cell number and density were smaller in SHR and G ratio was larger in SHR, indicating that SHR have thinner myelinated fibers. CONCLUSION: Sural nerve morphology is similar between WKY and WR, allowing the use of WR as the SHR controls in morphological investigations involving peripheral neuropathies.

Potassium ion accumulation at the external surface of the nodal membrane in frog myelinated fibers.

Moran, N; Palti, Y; Levitan, E; Stämpfli, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1980 EN
Relevância na Pesquisa
48.242134%
Potassium accumulation associated with outward membrane potassium current was investigated experimentally in myelinated fibers and analyzed in terms of two models-three-compartment and diffusion in an unstirred layer. In the myelinated fibers, as in squid giant axons, the three-compartment model satisfactorily describes potassium accumulation. Within this framework the average space thickness, theta, in frog was 5,900 +/- 700 A, while the permeability coefficient of the external barrier, PK, was (1.5 +/- 0.1) X 10(-2) cm/s. The model of ionic diffusion in an unstirred aqueous layer adjacent to the axolemma, as an alternative explanation for ion accumulation, was also consistent with the experimental data, provided that D, the diffusion constant, was (1.8 +/- 0.2) X 10(-6) cm/s and l, the unstirred layer thickness, was 1.4 +/- 0.1 micron, i.e., similar to the depth of the nodal gap. An empirical equation relating the extent of potassium accumulation to the amplitude and duration of depolarization is given.

Neurotrophic Modulation of Myelinated Cutaneous Innervation and Mechanical Sensory Loss in Diabetic Mice

Christianson, Julie A.; Ryals, Janelle M.; Johnson, Megan S.; Dobrowsky, Rick T.; Wright, Douglas E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
38.91339%
Human diabetic patients often lose touch and vibratory sensations, but to date, most studies on diabetes-induced sensory nerve degeneration have focused on epidermal C-fibers. Here, we explored the effects of diabetes on cutaneous myelinated fibers in relation to the behavioral responses to tactile stimuli from diabetic mice. Weekly behavioral testing began prior to STZ administration and continued until 8 weeks, at which time myelinated fiber innervation was examined in the footpad by immunohistochemistry using antiserum to NF-H and MBP. Diabetic mice developed reduced behavioral responses to non-noxious (monofilaments) and noxious (pin prick) stimuli. In addition, diabetic mice displayed a 50% reduction in NF-H-positive myelinated innervation of the dermal footpad compared to non-diabetic mice. To test whether two neurotrophins NGF and/or NT-3 known to support myelinated cutaneous fibers could influence myelinated innervation, diabetic mice were treated intrathecally for two weeks with NGF, NT-3, NGF and NT-3. Neurotrophin-treated mice were then compared to diabetic mice treated with insulin for two weeks. NGF and insulin treatment both increased paw withdrawal to mechanical stimulation in diabetic mice, whereas NT-3 or a combination of NGF and NT-3 failed to alter paw withdrawal responses. Surprisingly...

The twitcher mouse. An alteration of the unmyelinated fibers in the PNS.

Kobayashi, S.; Katayama, M.; Satoh, J.; Suzuki, K.; Suzuki, K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1988 EN
Relevância na Pesquisa
38.264146%
The twitcher is an authentic murine model of globoid cell leukodystrophy (GLD) in man. Extensive demyelination of the central and peripheral nervous systems (CNS and PNS) characterizes the neuropathologic features of GLD. In the common peroneal nerve of the twitcher, where demyelination was extensive, pronounced morphologic and quantitative alterations were noted in the unmyelinated fibers. They were 1) a large number of long and attenuated cellular processes of Schwann cells, which often enclosed only one or two axons; and 2) a threefold increase in the number of Schwann cell-axon units with reduced numbers of axons per unit. These results suggested increased branching of unmyelinated Schwann cells. Mild increase in unmyelinated fibers and mild decrease in myelinated fibers were additional features. In contrast, the sympathetic nerve trunk, which had only small numbers of myelinated and rare or no demyelinated fibers, showed much milder alterations in the unmyelinated fibers. Thus, the results of our study suggest that the alterations of the Schwann cells of the unmyelinated fibers in the twitcher are secondary to or in association with the chronic demyelinating process.

Ex vivo and in vivo imaging of myelin fibers in mouse brain by coherent anti-Stokes Raman scattering microscopy

Fu, Yan; Huff, T. Brandon; Wang, Han-Wei; Wang, Haifeng; Cheng, Ji-Xin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 24/11/2008 EN
Relevância na Pesquisa
38.242134%
Coherent anti-Stokes Raman scattering (CARS) microscopy was applied to image myelinated fibers in different regions of a mouse brain. The CARS signal from the CH2 symmetric stretching vibration allows label-free imaging of myelin sheath with 3D sub-micron resolution. Compared with two-photon excited fluorescence imaging with lipophilic dye labeling, CARS microscopy provides sharper contrast and avoids photobleaching. The CARS signal exhibits excitation polarization dependence which can be eliminated by reconstruction of two complementary images with perpendicular excitation polarizations. The capability of imaging myelinated fibers without exogenous labeling was used to map the whole brain white matter in brain slices and to analyze the microstructural anatomy of brain axons. Quantitative information about fiber volume%, myelin density, and fiber orientations was derived. Combining CARS with two-photon excited fluorescence allowed multimodal imaging of myelinated axons and other cells. Furthermore, in vivo CARS imaging on an upright microscope clearly identified fiber bundles in brain subcortex white matter. These advances open up new opportunities for the study of brain connectivity and neurological disorders.

Stereological estimation of the total number of myelinated callosal fibers in human subjects

Riise, Jesper; Pakkenberg, Bente
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
38.702913%
Using the fractionator principle, the total number, density and diameter size of myelinated callosal fibers were estimated in the corpus callosum (CC) of 10 Danish males between 39 and 60 years of age. All sampled brains had been used in previous quantitative studies, for example, studies of neocortical neuron number, and were selected to determine whether the variability in the neocortical neuron number correlated with the total number of myelinated callosal fibers. Middle-aged males had an average of 138 × 106 (coefficient of variance; CV = 0.19) myelinated fibers, but did not show any correlation with the neocortical neuron number (r = 0.25; P = 0.49). The mean area of the CC was estimated to be 7.2 cm2 (CV = 0.17), and showed a significant correlation with the number of callosal fibers (r = 0.69, P = 0.041). Additionally, an overall density decline from the anterior to the posterior region of the CC was observed, with an inverse relationship between the distribution of large and small fibers along the callosal axis. This study suggests that many mechanisms are involved in the development and determination of axonal projections across the CC that cannot simply be explained by the neocortical neuron number. Further, a positive correlation between callosal fibers and the CC area verifies that callosal fibers are the factor responsible for CC size. Finally...

A role for nociceptive, myelinated nerve fibers in itch sensation

Ringkamp, M.; Schepers, R. J.; Shimada, S.G.; Johanek, L.M.; Hartke, T.V.; Borzan, J.; Shim, B.; LaMotte, R.H.; Meyer, R.A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 19/10/2011 EN
Relevância na Pesquisa
38.94144%
Despite its clinical importance, the underlying neural mechanisms of itch sensation are poorly understood. In many diseases, pruritus is not effectively treated with antihistamines, indicating the involvement of non-histaminergic mechanisms. To investigate the role of small myelinated afferents in non-histaminergic itch, we tested, in psychophysical studies in humans, the effect of a differential nerve block on itch produced by intradermal insertion of spicules from the pods of a cowhage plant (Mucuna pruriens). Electrophysiological experiments in anesthetized monkey were used to investigate the responsiveness of cutaneous, nociceptive, myelinated afferents to different chemical stimuli (cowhage spicules, histamine, capsaicin). Our results provide several lines of evidence for an important role of myelinated fibers in cowhage-induced itch: 1) a selective conduction block in myelinated fibers substantially reduces itch in a sub-group of subjects with A-fiber dominated itch, 2) the time course of itch sensation differs between subjects with A-fiber versus C-fiber dominated itch, 3) cowhage activates a subpopulation of myelinated and unmyelinated afferents in monkey, 4) the time course of the response to cowhage is different in myelinated and unmyelinated fibers...

High Frequency Stimulation Selectively Blocks Different Types of Fibers in Frog Sciatic Nerve

Joseph, Laveeta; Butera, Robert J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
38.55619%
Conduction block using high frequency alternating current (HFAC) stimulation has been shown to reversibly block conduction through various nerves. However, unlike simulations and experiments on myelinated fibers, prior experimental work in our lab on the sea-slug, Aplysia, found a nonmonotonic relationship between frequency and blocking thresholds in the unmyelinated fibers. To resolve this discrepancy, we investigated the effect of HFAC waveforms on the compound action potential of the sciatic nerve of frogs. Maximal stimulation of the nerve produces a compound action potential consisting of the A-fiber and C-fiber components corresponding to the myelinated and unmyelinated fibers’ response. In our study, HFAC waveforms were found to induce reversible block in the A-fibers and C-fibers for frequencies in the range of 5–50 kHz and for amplitudes from 0.1–1 mA. Although the A-fibers demonstrated the monotonically increasing threshold behavior observed in published literature, the C-fibers displayed a nonmonotonic relationship, analogous to that observed in the unmyelinated fibers of Aplysia. This differential blocking behavior observed in myelinated and unmyelinated fibers during application of HFAC waveforms has diverse implications for the fields of selective stimulation and pain management.

Ultrastructural Alterations of Myelinated Fibers and Oligodendrocytes in the Prefrontal Cortex in Schizophrenia: A Postmortem Morphometric Study

Uranova, Natalya A.; Vikhreva, Olga V.; Rachmanova, Valentina I.; Orlovskaya, Diana D.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
48.87409%
Schizophrenia is believed to result from altered neuronal connectivity and impaired myelination. However, there are few direct evidence for myelin abnormalities in schizophrenia. We performed electron microscopic study of myelinated fibers and oligodendrocytes and morphometric study of myelinated fibers in the prefrontal cortex in gray and white matters in schizophrenia and normal controls. Six types of abnormal fibers and ultrastructural alterations of oligodendrocytes were found in schizophrenia. No significant group differences in area density of myelinated fibers were found. Frequency of pathological fibers was increased significantly in gray matter in young and elderly schizophrenia patients and in patients with predominantly positive symptoms. In contrast, in white matter, frequency of altered fibers was increased significantly in elderly patients, in patients with predominantly negative symptoms, and correlated with illness duration. Progressive alterations of myelinated fibers in white matter might be followed by alterations of myelinated fibers in gray matter in schizophrenia.

Evaluating dermal myelinated nerve fibers in skin biopsy

Myers, M. Iliza; Peltier, Amanda C.; Li, Jun
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
38.660474%
Although there has been extensive research on small, unmyelinated fibers in the skin, little research has investigated dermal myelinated fibers in comparison. Glabrous, non-hairy skin contains mechanoreceptors that afford a vantage point for observation of myelinated fibers that have previously been seen only with invasively obtained nerve biopsies. This review discusses current morphometric and molecular expression data of normative and pathogenic glabrous skin obtained by various processing and analysis methods for cutaneous myelinated fibers. Recent publications have shed light on the role of glabrous skin biopsy in identifying signs of peripheral neuropathy and as a potential biomarker of distal myelin and mechanoreceptor integrity. The clinical relevance of a better understanding of the role of dermal myelinated nerve terminations in peripheral neuropathy will be addressed in light of recent publications in the growing field of skin biopsy.

Topohistology of sympathetic and parasympathetic nerve fibers in branches of the pelvic plexus: an immunohistochemical study using donated elderly cadavers

Hinata, Nobuyuki; Hieda, Keisuke; Sasaki, Hiromasa; Murakami, Gen; Abe, Shinichi; Matsubara, Akio; Miyake, Hideaki; Fujisawa, Masato
Fonte: Korean Association of Anatomists Publicador: Korean Association of Anatomists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
38.864233%
Although the pelvic autonomic plexus may be considered a mixture of sympathetic and parasympathetic nerves, little information on its composite fibers is available. Using 10 donated elderly cadavers, we investigated in detail the topohistology of nerve fibers in the posterior part of the periprostatic region in males and the infero-anterior part of the paracolpium in females. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were used as parasympathetic nerve markers, and tyrosine hydroxylase (TH) was used as a marker of sympathetic nerves. In the region examined, nNOS-positive nerves (containing nNOS-positive fibers) were consistently predominant numerically. All fibers positive for these markers appeared to be thin, unmyelinated fibers. Accordingly, the pelvic plexus branches were classified into 5 types: triple-positive mixed nerves (nNOS+, VIP+, TH+, thick myelinated fibers + or -); double-positive mixed nerves (nNOS+, VIP-, TH+, thick myelinated fibers + or -); nerves in arterial walls (nNOS-, VIP+, TH+, thick myelinated fibers-); non-parasympathetic nerves (nNOS-, VIP-, TH+, thick myelinated fibers + or -); (although rare) pure sensory nerve candidates (nNOS-, VIP-, TH-, thick myelinated fibers+). Triple-positive nerves were 5-6 times more numerous in the paracolpium than in the periprostatic region. Usually...

A quantitative study on changes of the myelinated fibers in the cerebral cortex of cortical dysplasia rats☆

Ma, Xuntai; Tang, Yong; Lv, Yang; Cheng, Oumei; Yan, Yong
Fonte: Medknow Publications & Media Pvt Ltd Publicador: Medknow Publications & Media Pvt Ltd
Tipo: Artigo de Revista Científica
Publicado em 05/02/2012 EN
Relevância na Pesquisa
48.242134%
An animal model of cortical dysplasia was established through X-ray irradiation induced subcortical heterotopic nodules in rats. Transmission electron microscopy detection of the ultrastructure and the stereology examination showed that there was a significant decrease in cerebral white matter and hippocampal volume, the total volume, volume density, length density and total length of the myelinated fibers in the white matter of cortical dysplasia rats. Subcortical heterotopic nodules of the hippocampal CA1 region and synaptic number density in the CA3 region were reduced compared with normal rats. Our experimental findings indicate that erosed subcortical heterotopic nodules, decreased total length of myelinated nerve fibers and demyelination directly lead to a reduction of white matter volume.

Computation of Impulse Conduction in Myelinated Fibers; Theoretical Basis of the Velocity-Diameter Relation

Goldman, L.; Albus, James S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1968 EN
Relevância na Pesquisa
48.00371%
For myelinated fibers, it is experimentally well established that spike conduction velocity is proportional to fiber diameter. However no really satisfactory theoretical treatment has been proposed. To treat this problem a theoretical axon was described consisting of lengths of passive leaky cable (internode) regularly interrupted by short isopotential patches of excitable membrane (node). The nodal membrane was assumed to obey the Frankenhaeuser-Huxley equations. The explicit diameter dependencies of the various parameters were incorporated into the equations. The fiber diameter to axon diameter ratio was taken to be constant, and the internode length was taken to be proportional to the fiber diameter. Both these conditions reflect the situation that exists in real, experimental fibers. Dimensional analysis shows that these anatomical conditions are equivalent to Rushton's (1951) assumption of corresponding states. Hence, conduction velocity will be proportional to fiber diameter, in complete agreement with the experimental findings. Digital computer solutions of these equations were made in order to compute a set of actual velocities. Computations made with constant internode length or constant myelin thickness (i.e., nonconstant fiber diameter to axon diameter ratio) did not show linearity of the velocity-diameter relation.