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Search Results: 1 - 10 of 525 matches for " myelin breakdown "
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Early myelin breakdown following sural nerve crush: a freeze-fracture study
Martinez, A.M.B.;Canavarro, S.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000001200012
Abstract: in this study we describe the early changes of the myelin sheath following surgical nerve crush. we used the freeze-fracture technique to better evaluate myelin alterations during an early stage of wallerian degeneration. rat sural nerves were experimentally crushed and animals were sacrificed by transcardiac perfusion 30 h after surgery. segments of the nerves were processed for routine transmission electron microscopy and freeze-fracture techniques. our results show that 30 h after the lesion there was asynchrony in the pattern of wallerian degeneration, with different nerve fibers exhibiting variable degrees of axon disruption. this was observed by both techniques. careful examination of several replicas revealed early changes in myelin membranes represented by vacuolization and splitting of consecutive lamellae, rearrangement of intramembranous particles and disappearance of paranodal transverse bands associated or not with retraction of paranodal myelin terminal loops from the axolemma. these alterations are compatible with a direct injury to the myelin sheath following nerve crush. the results are discussed in terms of a similar mechanism underlying both axon and myelin breakdown.
Early myelin breakdown following sural nerve crush: a freeze-fracture study
Martinez A.M.B.,Canavarro S.
Brazilian Journal of Medical and Biological Research , 2000,
Abstract: In this study we describe the early changes of the myelin sheath following surgical nerve crush. We used the freeze-fracture technique to better evaluate myelin alterations during an early stage of Wallerian degeneration. Rat sural nerves were experimentally crushed and animals were sacrificed by transcardiac perfusion 30 h after surgery. Segments of the nerves were processed for routine transmission electron microscopy and freeze-fracture techniques. Our results show that 30 h after the lesion there was asynchrony in the pattern of Wallerian degeneration, with different nerve fibers exhibiting variable degrees of axon disruption. This was observed by both techniques. Careful examination of several replicas revealed early changes in myelin membranes represented by vacuolization and splitting of consecutive lamellae, rearrangement of intramembranous particles and disappearance of paranodal transverse bands associated or not with retraction of paranodal myelin terminal loops from the axolemma. These alterations are compatible with a direct injury to the myelin sheath following nerve crush. The results are discussed in terms of a similar mechanism underlying both axon and myelin breakdown.
Autoantibodies against myelin antigens in patients with neuromyelitis optica  [PDF]
Kota Moriguchi, Katsuichi Miyamoto, Juri Ichihashi, Susumu Kusunoki
Open Journal of Immunology (OJI) , 2013, DOI: 10.4236/oji.2013.32007
Abstract:

In this study, we investigated the clinical relevance of anti-myelin antibodies in patients with neuromyelitis optica (NMO); titers of antibodies against myelin oligodendrocyte glycoproteins, proteolipid proteins and myelin basic proteins were measured in the sera of patients with NMO and compared to healthy controls, as well as to patients with other diseases. The frequency of presence of anti-myelin antibodies in patients with NMO was significantly higher than that in healthy and diseased controls. The expanded disability status scale scores correlated with the titers of the anti-myelin antibodies. Patients with anti-myelin antibody exhibited other autoantibodies significantly more frequently than patients without the antibody. Anti-myelin antibodies may be useful markers for predicting severe clinical courses in patients with NMO.

Remyelination in experimentally demyelinated connexin 32 KnockOut mice
Ramos, Adriano Tony;Maiorka, Paulo César;Dagli, Maria Lúcia Zaidan;Hosomi, Fernando Yutaka Moniwa;Violin, Kalan Bastos;Latorre, Andréa;Viott, Aline de Marco;Masuda, Eduardo Kenji;Trost, Maria Elisa;Martins, Tessie Beck;Gra?a, Dominguita Lühers;
Arquivos de Neuro-Psiquiatria , 2009, DOI: 10.1590/S0004-282X2009000300020
Abstract: the aim of this study was to evaluate the role of connexin 32 (cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1% ethidium bromide solution or saline in the sciatic nerve of cx 32 knockout mice. euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. within the sciatic nerves, schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. we concluded that the regeneration of lost myelin sheaths within the pns followed the pattern already reported for this model in other laboratory species. therefore, these results suggest that absence of cx 32 did not interfere with the normal pattern of remyelination in this model in young mice.
Reprogramming Cells for Brain Repair
Alyx T. Guarino,Randall D. McKinnon
Brain Sciences , 2013, DOI: 10.3390/brainsci3031215
Abstract: At present there are no clinical therapies that can repair traumatic brain injury, spinal cord injury or degenerative brain disease. While redundancy and rewiring of surviving circuits can recover some lost function, the brain and spinal column lack sufficient endogenous stem cells to replace lost neurons or their supporting glia. In contrast, pre-clinical studies have demonstrated that exogenous transplants can have remarkable efficacy for brain repair in animal models. Mesenchymal stromal cells (MSCs) can provide paracrine factors that repair damage caused by ischemic injury, and oligodendrocyte progenitor cell (OPC) grafts give dramatic functional recovery from spinal cord injury. These studies have progressed to clinical trials, including human embryonic stem cell (hESC)-derived OPCs for spinal cord repair. However, ESC-derived allografts are less than optimal, and we need to identify a more appropriate donor graft population. The cell reprogramming field has developed the ability to trans-differentiate somatic cells into distinct cell types, a technology that has the potential to generate autologous neurons and glia which address the histocompatibility concerns of allografts and the tumorigenicity concerns of ESC-derived grafts. Further clarifying how cell reprogramming works may lead to more efficient direct reprogram approaches, and possibly in vivo reprogramming, in order to promote brain and spinal cord repair.
Microfinance Risk Management with Work Breakdown Structure  [PDF]
Junxiang Liu
Journal of Financial Risk Management (JFRM) , 2012, DOI: 10.4236/jfrm.2012.13007
Abstract: Building inclusive financial system in China makes microfinance products become practical tools in solving financial difficulties of small and medium enterprises (SMEs). Discuss general management risk of microfinance under effective credit structure and then analyze the Work Breakdown Structure (WBS) in microfinance management from the perspective of project management effectiveness. Moreover, use ergonomics and probability theories to find out the effects on microfinance management through institutions with simpleness and swift. It is demonstrated that optimization of microfinance management program under inclusive financial sectors can probably be beneficial to microfinance credit risk control
Kalai-Smorodinsky Bargaining Solution and Alternating Offers Game  [PDF]
Yoichi Nishihara
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.31012
Abstract: This article presents an alternating offers game that supports a Kalai-Smorodinsky bargaining solution (KSS). It is well known that a solution to an alternating offers game has a breakdown point equivalent to a status quo that converges to its Nash bargaining solution because the probability of breakdown becomes negligible, whereas we show that a KSS is obtained if a breakdown gives everything to the player who rejects. The former option, which is adopted by many application papers may be suitable for ex ante production. However, the latter option should be more appropriate for ex post production, because players do not need to be concerned with cooperation.
Mechanism of Generation and Collapse of a Longitudinal Vortex System Induced around the Leading Edge of a Delta Wing  [PDF]
Shigeru Ogawa, Jumpei Takeda
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.53028
Abstract: The purpose of the paper is to clarify the mechanism of generation and collapse of a longitudinal vortex system induced around the leading edge of a delta wing. CFD captured well characteristics of flow structure of the vortex system. It is found that the vortex system has a cone-shaped configuration, and both rotational velocity and vorticity have their largest values at the tip of the vortex and reduce downstream along the vortical axis. This resulted in inducing the largest negative pressure at the tip of the delta wing surface. The collapse of the vortex system was also studied. The system can still remain until the tip angle of 110 degrees. However, between 110 degrees and 120 degrees, the system becomes unstable. Over 120 degrees, the characteristics of the vortex are considered to have converted from the longitudinal vortex to the transverse one.
Numerical Investigation of the Plasma Formation in Distilled Water by Nd-YAG Laser Pulses of Different Duration  [PDF]
Laila H. Gaabour, Yosr Ezz El Din Gamal, G. Abdellatif
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.330206
Abstract: Water breakdown studies by Nd-YAG laser pulses of duration 100 fs, 30 ps and 6 ns at wavelength 1064 nm are pre- formed to investigate the physical mechanisms which couple the laser energy into the medium. Calculations are carried out applying a modified kinetic model of water breakdown previously developed by Kennedy (1995) to investigate the correlation between threshold intensity of breakdown and laser pulse length. The modifications considered the introduction of diffusion and recombination loss processes which might take place under the experimental conditions applied in these calculations. The validity of the model is tested by comparing the calculated threshold intensities and the experimentally measured ones where good agreement is shown. The study of the time evolution of the electron density clarifies the correlation between the pulse length and dominant ionization mechanism. The analysis of the spatial distribution of the electron density along the radial and axial distances of the focal spot showed that the size of the formed plasma increases with the increase of the pulse length. On the other hand, studies of self-focusing effect illustrated that under the investigated experimental conditions the effect of this process has an effective contribution only at laser pulses of the order of femtosecond scale when the laser beam is focused by a lens of a focal length ≥8.0 cm. This result in turns assures that using femtosecond pulses in ophthalmic microsurgery could be a safe tool from the retinal damage.
Conformational epitopes of myelin oligodendrocyte glycoprotein are targets of potentially pathogenic antibody responses in multiple sclerosis
Til Menge, Patrice H Lalive, H -Christian von Büdingen, Claude P Genain
Journal of Neuroinflammation , 2011, DOI: 10.1186/1742-2094-8-161
Abstract: Sera of 325 MS patients, 69 patients with clinically isolated syndrome and 164 healthy controls were assayed by quantitative, high-throughput ELISA for reactivity to 3 different MOG isoforms, and quantitative titers correlated with clinical characteristics. mAbs defined unique immunodominant epitopes distinct to each of the isoforms.In the majority of human samples anti-MOG levels were skewed towards low titers. However, in 8.2% of samples high-titer anti-MOG antibodies were identified. In contrast to anti-MOG reactivity observed in a mouse model of MS, in patients with MS these never reacted with ubiquitously exposed epitopes. Moreover, in patients with relapsing-remitting MS high-titer anti-MOG IgG correlated with disability (EDSS; Spearman r = 0.574; p = 0.025).Thus high-titer reactivity likely represents high-affinity antibodies against pathologically relevant MOG epitopes, that are only present in a small proportion of patients with MS. Our study provides valuable information about requirements of anti-MOG reactivity for being regarded as a prognostic biomarker in a subtype of MS.Autoantibodies directed against myelin antigens have been a long-standing focus of interest in multiple sclerosis (MS) research, especially those binding to myelin oligodendrocyte glycoprotein (MOG). MOG is predominantly expressed in the CNS, and is exposed on the outermost lamellae of the myelin sheath thus readily available for a humoral immune attack [1]. MOG induces demyelinating experimental allergic encephalomyelitis (EAE), the animal model of MS, in a variety of species both by active immunization and by passively transferred anti-MOG antibodies (reviewed by [1,2]). Only those anti-MOG antibodies directed against conformational epitopes, as opposed to linear epitopes, appear to be pathogenic in EAE [3-5]. Recently, it was shown that the murine monoclonal antibody (mAb) 8.18.c5 specific for rat MOG, that confers demyelination, maps to a discontinuous epitope of the surface expose
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