The Experts below are selected from a list of 10302 Experts worldwide ranked by ideXlab platform
Reinhilde Jacobs - One of the best experts on this subject based on the ideXlab platform.
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peri implant Myelinated Nerve fibers histological findings in dogs
Journal of Periodontal Research, 2020Co-Authors: Dandan Song, Xin Liang, Hui Zheng, Sohaib Shujaat, Jeroen Van Dessel, Weijian Zhong, Ivo Lambrichts, Reinhilde JacobsAbstract:Background and objective While osseointegration following various dental implant placement protocols has been extensively investigated, the neurohistological integration has received little attention. The primary aim of this study was to compare the Myelinated Nerve fibers density in peri-implant bone tissue following various implant placement protocols. The secondary aim assessed the effect of follow-up on peri-implant Nerve fibers density. Methods Ten beagle dogs randomly received 68 commercially pure titanium implants in the mandibular premolar or molar region bilaterally following extraction utilizing one of the six treatment protocols: (a) immediate implant placement (IIP) and immediate loading (IL); (b) IIP and delayed loading (DL); (c) IIP and left unloaded (UL); (d) delayed implant placement (DIP) and IL; (e) DIP and DL; and (f) DIP and UL. Histomorphometric analysis of the peri-implant Myelinated Nerve fibers was performed in a 300 μm peri-implant zone at the cervical, middle, and apical level following implant placement. The follow-up assessment involved longitudinal observation at 3 months following each implant treatment protocol and at 6 months for IIP+IL and IIP+DL protocols. Results The influence of different treatment protocols, including the fixed effects of implant groups (IIP+IL, IIP+DL, IIP+UL, DIP+IL, DIP+DL, DIP+UL) and regions (cervical, middle, apical), was examined via a linear mixed model. The IIP+IL group showed a significantly higher Myelinated Nerve density compared to the IIP+UL and DIP+UL group. Peri-implant Nerve re-innervation was significantly higher (P = .002) in the apical region compared to the cervical region. After immediate implant placement, the IL group showed a significantly (P = .03) higher density of Myelinated Nerve fibers compared to DL. No significant (P = .19) effect of follow-up on Nerve density was observed. Conclusion The immediate implant placement and loading protocol showed most beneficial effect on peri-implant innervation with highest Myelinated Nerve density in the apical region. A longer loading time had no influence on the peri-implant Nerve density.
Alan Peters - One of the best experts on this subject based on the ideXlab platform.
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age changes in Myelinated Nerve fibers of the cingulate bundle and corpus callosum in the rhesus monkey
The Journal of Comparative Neurology, 2010Co-Authors: Alan Peters, Michael P Bowley, Howard Cabral, Douglas L RoseneAbstract:Aging is accompanied by deficits in cognitive function, which may be related to the vulnerability of Myelinated Nerve fibers to the normal process of aging. Loss of Nerve fibers, together with age-related alterations in myelin sheath structure, may result in the inefficient and poorly coordinated conduction of neuronal signals. Until now, the ultrastructural analysis of cerebral white matter fiber tracts associated with frontal lobe areas critical in cognitive processing has been limited. In this study we analyzed the morphology and area number density of Myelinated Nerve fibers in the cingulate bundle and genu of the corpus callosum in behaviorally assessed young, middle aged, and old rhesus monkeys (Macaca mulatta). In both structures, normal aging results in a 20% decrease in the number of Myelinated Nerve fibers per unit area, while remaining Nerve fibers exhibit an increasing frequency of degenerative changes in their myelin sheaths throughout middle and old age. Concomitantly, myelination continues in older monkeys, suggesting ongoing, albeit inadequate, reparative processes. Despite similar patterns of degeneration in both fiber tracts, only the age-related changes in the cingulate bundle correlate with declining cognitive function, underscoring its role as a critical corticocortical pathway linking the medial prefrontal, cingulate, and parahippocampal cortices in processes of working memory, recognition memory, and other higher cognitive faculties. These results further demonstrate the important role Myelinated Nerve fiber degeneration plays in the pathogenesis of age-related cognitive decline.
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the effects of normal aging on Myelinated Nerve fibers in monkey central nervous system
Frontiers in Neuroanatomy, 2009Co-Authors: Alan PetersAbstract:The effects of aging on Myelinated Nerve fibers of the central nervous system are complex. Many Myelinated Nerve fibers in white matter degenerate and are lost, leading to some disconnections between various parts of the central nervous system. Other Myelinated Nerve fibers are affected differently, because only their sheaths degenerate, leaving the axons intact. Such axons are reMyelinated by a series of internodes that are much shorter than the original ones and are composed of thinner sheaths. Thus the myelin-forming cells of the central nervous system, the oligodendrocytes, remain active during aging. Indeed, not only do these neuroglial cell remyelinate axons, with age they also continue to add lamellae to the myelin sheaths of intact Nerve fibers, so that sheaths become thicker. It is presumed that the degeneration of myelin sheaths is due to the degeneration of the parent oligodendrocyte, and that the production of increased numbers of internodes as a consequence of remyelination requires additional oligodendrocytes. Whether there is a turnover of oligodendrocytes during life has not been studied in primates, but it has been established that over the life span of the monkey, there is a substantial increase in the numbers of oligodendrocytes. While the loss of some Myelinated Nerve fibers leads to some disconnections, the degeneration of other myelin sheaths and the subsequent remyelination of axons by shorter internodes slow down the rate conduction along Nerve fibers. These changes affect the integrity and timing in neuronal circuits, and there is evidence that they contribute to cognitive decline.
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disrupted myelin and axon loss in the anterior commissure of the aged rhesus monkey
The Journal of Comparative Neurology, 2003Co-Authors: Julie H Sandell, Alan PetersAbstract:This study assesses the effects of age on the composition of the anterior commissure of the rhesus monkey. The anterior commissures of nine young (5–10 years), five middle-aged (15–20 years), and eight old (25–35 years) monkeys were examined by light and electron microscopy. In all, 90 –95% of the Nerve fibers in the anterior commissure are Myelinated. With age, the structure of the myelin sheaths of some Nerve fibers is altered. Some of the axons also show signs of degeneration and this leads to a loss of Nerve fibers. Thus, in young and the middle-aged monkeys the mean number of Myelinated Nerve fibers in the anterior commissure is 2.2 10 6 , while in the old monkeys the mean is 1.2 10 6 . Increasing age is correlated with a reduction in the number of Myelinated Nerve fibers in the anterior commissure, an increase in the frequency of structural alterations in myelin sheaths, and an increase in the frequency of occurrence of degenerating axons. However, the number of Myelinated Nerve fibers is the only variable that correlates with cognition: in monkeys 5–20 years of age the fewer the number of Nerve fibers the poorer the cognitive performance, as measured by our Cognitive Impairment Index (CII). The most common neuroglial cells in the anterior commissure are oligodendrocytes. They account for 86% of all neuroglial cell profiles, while astrocytes account for 9%, and microglial cells for 5% of profiles. There is no apparent change with age in the total numbers of neuroglial cells, although as they age each of the neuroglial cell types acquires some inclusions in their cytoplasm. The data, together with those from previous studies, support the concept that in aging there is a ubiquitous loss of Myelinated Nerve fibers from the brain and that fiber loss is preceded by alterations in the structure of many of the myelin sheaths. J. Comp. Neurol. 466:14 –30, 2003. © 2003 Wiley-Liss, Inc. Indexing terms: aging; primate; astrocyte; oligodendrocyte; microglia; electron microscopy; axon; Nerve fibers
Amanda Peltier - One of the best experts on this subject based on the ideXlab platform.
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evaluation of dermal Myelinated Nerve fibers in diabetes mellitus
Journal of The Peripheral Nervous System, 2013Co-Authors: Amanda Peltier, Iliza M Myers, Kay Artibee, Audra D Hamilton, Qing Yan, Jiasong Guo, Yaping Shi, Lily WangAbstract:Skin biopsies have primarily been used to study the non-Myelinated Nerve fibers of the epidermis in a variety of neuropathies. In this study, we have expanded the skin biopsy technique to glabrous, non-hairy skin to evaluate Myelinated Nerve fibers in the most highly prevalent peripheral Nerve disease, diabetic polyneuropathy (DPN). Twenty patients with DPN (Type I, n = 9; Type II, n = 11) and 16 age-matched healthy controls (age 29-73) underwent skin biopsy of the index finger, Nerve conduction studies (NCS), and composite neuropathy scoring. In patients with DPN, we found a statistically significant reduction of both mechanoreceptive Meissner corpuscles (MCs) and their afferent Myelinated Nerve fibers (p = 0.01). This Myelinated Nerve fiber loss was correlated with the decreased amplitudes of sensory/motor responses in NCS. This study supports the utilization of skin biopsy to quantitatively evaluate axonal loss of Myelinated Nerve fibers in patients with DPN.
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evaluating dermal Myelinated Nerve fibers in skin biopsy
Muscle & Nerve, 2013Co-Authors: Iliza M Myers, Amanda PeltierAbstract: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.
Douglas L Rosene - One of the best experts on this subject based on the ideXlab platform.
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statistical physics approach to quantifying differences in Myelinated Nerve fibers
Scientific Reports, 2015Co-Authors: Cesar H Comin, Douglas L Rosene, J R L Santos, D Corradini, Will Morrison, Chester Curme, Andrea Gabrielli, Luciano Da Fontoura CostaAbstract:We present a new method to quantify differences in Myelinated Nerve fibers. These differences range from morphologic characteristics of individual fibers to differences in macroscopic properties of collections of fibers. Our method uses statistical physics tools to improve on traditional measures, such as fiber size and packing density. As a case study, we analyze cross–sectional electron micrographs from the fornix of young and old rhesus monkeys using a semi-automatic detection algorithm to identify and characterize Myelinated axons. We then apply a feature selection approach to identify the features that best distinguish between the young and old age groups, achieving a maximum accuracy of 94% when assigning samples to their age groups. This analysis shows that the best discrimination is obtained using the combination of two features: the fraction of occupied axon area and the effective local density. The latter is a modified calculation of axon density, which reflects how closely axons are packed. Our feature analysis approach can be applied to characterize differences that result from biological processes such as aging, damage from trauma or disease or developmental differences, as well as differences between anatomical regions such as the fornix and the cingulum bundle or corpus callosum.
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age changes in Myelinated Nerve fibers of the cingulate bundle and corpus callosum in the rhesus monkey
The Journal of Comparative Neurology, 2010Co-Authors: Alan Peters, Michael P Bowley, Howard Cabral, Douglas L RoseneAbstract:Aging is accompanied by deficits in cognitive function, which may be related to the vulnerability of Myelinated Nerve fibers to the normal process of aging. Loss of Nerve fibers, together with age-related alterations in myelin sheath structure, may result in the inefficient and poorly coordinated conduction of neuronal signals. Until now, the ultrastructural analysis of cerebral white matter fiber tracts associated with frontal lobe areas critical in cognitive processing has been limited. In this study we analyzed the morphology and area number density of Myelinated Nerve fibers in the cingulate bundle and genu of the corpus callosum in behaviorally assessed young, middle aged, and old rhesus monkeys (Macaca mulatta). In both structures, normal aging results in a 20% decrease in the number of Myelinated Nerve fibers per unit area, while remaining Nerve fibers exhibit an increasing frequency of degenerative changes in their myelin sheaths throughout middle and old age. Concomitantly, myelination continues in older monkeys, suggesting ongoing, albeit inadequate, reparative processes. Despite similar patterns of degeneration in both fiber tracts, only the age-related changes in the cingulate bundle correlate with declining cognitive function, underscoring its role as a critical corticocortical pathway linking the medial prefrontal, cingulate, and parahippocampal cortices in processes of working memory, recognition memory, and other higher cognitive faculties. These results further demonstrate the important role Myelinated Nerve fiber degeneration plays in the pathogenesis of age-related cognitive decline.
J Mizrahi - One of the best experts on this subject based on the ideXlab platform.
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generalized cable equation model for Myelinated Nerve fiber
IEEE Transactions on Biomedical Engineering, 2005Co-Authors: P D Einziger, L M Livshitz, J MizrahiAbstract:Herein, the well-known cable equation for nonMyelinated axon model is extended analytically for Myelinated axon formulation. The Myelinated membrane conductivity is represented via the Fourier series expansion. The classical cable equation is thereby modified into a linear second order ordinary differential equation with periodic coefficients, known as Hill's equation. The general internal source response, expressed via repeated convolutions, uniformly converges provided that the entire periodic membrane is passive. The solution can be interpreted as an extended source response in an equivalent nonMyelinated axon (i.e., the response is governed by the classical cable equation). The extended source consists of the original source and a novel activation function, replacing the periodic membrane in the Myelinated axon model. Hill's equation is explicitly integrated for the specific choice of piecewise constant membrane conductivity profile, thereby resulting in an explicit closed form expression for the transmembrane potential in terms of trigonometric functions. The Floquet's modes are recognized as the Nerve fiber activation modes, which are conventionally associated with the nonlinear Hodgkin-Huxley formulation. They can also be incorporated in our linear model, provided that the periodic membrane point-wise passivity constraint is properly modified. Indeed, the modified condition, enforcing the periodic membrane passivity constraint on the average conductivity only leads, for the first time, to the inclusion of the Nerve fiber activation modes in our novel model. The validity of the generalized transmission-line and cable equation models for a Myelinated Nerve fiber, is verified herein through a rigorous Green's function formulation and numerical simulations for transmembrane potential induced in three-dimensional Myelinated cylindrical cell. It is shown that the dominant pole contribution of the exact modal expansion is the transmembrane potential solution of our generalized model.
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transmission line model for Myelinated Nerve fiber
International Conference of the IEEE Engineering in Medicine and Biology Society, 2005Co-Authors: P D Einziger, L M Livshitz, J MizrahiAbstract:Herein, the well-known cable equation for non-Myelinated axon model is extended analytically for Myelinated axon formulation. The classical cable equation is thereby modified into a linear second order ordinary differential equation with periodic coefficient, known as Hill's equation. Hill's equation exhibits periodic solutions, known as Floquet's modes. The Floquet's modes are recognized as the Nerve fiber activation modes, which are conventionally associated with the nonlinear Hodgkin-Huxley formulation. They can also be incorporated in our linear model
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generalized transmission line model for Myelinated Nerve fiber
IEEE Antennas and Propagation Society International Symposium, 2004Co-Authors: L M Livshitz, P D Einziger, M Dolgin, J MizrahiAbstract:The validity of the generalized transmission-line and cable equation models for Myelinated Nerve fiber, is verified herein through rigorous Green's function formulation for transmembrane potential induced in a 3D Myelinated cylindrical cell. It is shown that the dominant pole contribution of the exact modal expansion is the transmembrane potential solution of our generalized model.
